Initial import

1 files changed, 9037 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
new file mode 100644
index 000000000..84f9dead6
--- /dev/null
+++ b/drivers/md/md.c
@@ -0,0 +1,9037 @@
+/*
+   md.c : Multiple Devices driver for Linux
+     Copyright (C) 1998, 1999, 2000 Ingo Molnar
+
+     completely rewritten, based on the MD driver code from Marc Zyngier
+
+   Changes:
+
+   - RAID-1/RAID-5 extensions by Miguel de Icaza, Gadi Oxman, Ingo Molnar
+   - RAID-6 extensions by H. Peter Anvin <hpa@zytor.com>
+   - boot support for linear and striped mode by Harald Hoyer <HarryH@Royal.Net>
+   - kerneld support by Boris Tobotras <boris@xtalk.msk.su>
+   - kmod support by: Cyrus Durgin
+   - RAID0 bugfixes: Mark Anthony Lisher <markal@iname.com>
+   - Devfs support by Richard Gooch <rgooch@atnf.csiro.au>
+
+   - lots of fixes and improvements to the RAID1/RAID5 and generic
+     RAID code (such as request based resynchronization):
+
+     Neil Brown <neilb@cse.unsw.edu.au>.
+
+   - persistent bitmap code
+     Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   You should have received a copy of the GNU General Public License
+   (for example /usr/src/linux/COPYING); if not, write to the Free
+   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include <linux/kthread.h>
+#include <linux/blkdev.h>
+#include <linux/sysctl.h>
+#include <linux/seq_file.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/ctype.h>
+#include <linux/string.h>
+#include <linux/hdreg.h>
+#include <linux/proc_fs.h>
+#include <linux/random.h>
+#include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/file.h>
+#include <linux/compat.h>
+#include <linux/delay.h>
+#include <linux/raid/md_p.h>
+#include <linux/raid/md_u.h>
+#include <linux/slab.h>
+#include "md.h"
+#include "bitmap.h"
+#include "md-cluster.h"
+
+#ifndef MODULE
+static void autostart_arrays(int part);
+#endif
+
+/* pers_list is a list of registered personalities protected
+ * by pers_lock.
+ * pers_lock does extra service to protect accesses to
+ * mddev->thread when the mutex cannot be held.
+ */
+static LIST_HEAD(pers_list);
+static DEFINE_SPINLOCK(pers_lock);
+
+struct md_cluster_operations *md_cluster_ops;
+EXPORT_SYMBOL(md_cluster_ops);
+struct module *md_cluster_mod;
+EXPORT_SYMBOL(md_cluster_mod);
+
+static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
+static struct workqueue_struct *md_wq;
+static struct workqueue_struct *md_misc_wq;
+
+static int remove_and_add_spares(struct mddev *mddev,
+				 struct md_rdev *this);
+static void mddev_detach(struct mddev *mddev);
+
+/*
+ * Default number of read corrections we'll attempt on an rdev
+ * before ejecting it from the array. We divide the read error
+ * count by 2 for every hour elapsed between read errors.
+ */
+#define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
+/*
+ * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
+ * is 1000 KB/sec, so the extra system load does not show up that much.
+ * Increase it if you want to have more _guaranteed_ speed. Note that
+ * the RAID driver will use the maximum available bandwidth if the IO
+ * subsystem is idle. There is also an 'absolute maximum' reconstruction
+ * speed limit - in case reconstruction slows down your system despite
+ * idle IO detection.
+ *
+ * you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
+ * or /sys/block/mdX/md/sync_speed_{min,max}
+ */
+
+static int sysctl_speed_limit_min = 1000;
+static int sysctl_speed_limit_max = 200000;
+static inline int speed_min(struct mddev *mddev)
+{
+	return mddev->sync_speed_min ?
+		mddev->sync_speed_min : sysctl_speed_limit_min;
+}
+
+static inline int speed_max(struct mddev *mddev)
+{
+	return mddev->sync_speed_max ?
+		mddev->sync_speed_max : sysctl_speed_limit_max;
+}
+
+static struct ctl_table_header *raid_table_header;
+
+static struct ctl_table raid_table[] = {
+	{
+		.procname	= "speed_limit_min",
+		.data		= &sysctl_speed_limit_min,
+		.maxlen		= sizeof(int),
+		.mode		= S_IRUGO|S_IWUSR,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "speed_limit_max",
+		.data		= &sysctl_speed_limit_max,
+		.maxlen		= sizeof(int),
+		.mode		= S_IRUGO|S_IWUSR,
+		.proc_handler	= proc_dointvec,
+	},
+	{ }
+};
+
+static struct ctl_table raid_dir_table[] = {
+	{
+		.procname	= "raid",
+		.maxlen		= 0,
+		.mode		= S_IRUGO|S_IXUGO,
+		.child		= raid_table,
+	},
+	{ }
+};
+
+static struct ctl_table raid_root_table[] = {
+	{
+		.procname	= "dev",
+		.maxlen		= 0,
+		.mode		= 0555,
+		.child		= raid_dir_table,
+	},
+	{  }
+};
+
+static const struct block_device_operations md_fops;
+
+static int start_readonly;
+
+/* bio_clone_mddev
+ * like bio_clone, but with a local bio set
+ */
+
+struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
+			    struct mddev *mddev)
+{
+	struct bio *b;
+
+	if (!mddev || !mddev->bio_set)
+		return bio_alloc(gfp_mask, nr_iovecs);
+
+	b = bio_alloc_bioset(gfp_mask, nr_iovecs, mddev->bio_set);
+	if (!b)
+		return NULL;
+	return b;
+}
+EXPORT_SYMBOL_GPL(bio_alloc_mddev);
+
+struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
+			    struct mddev *mddev)
+{
+	if (!mddev || !mddev->bio_set)
+		return bio_clone(bio, gfp_mask);
+
+	return bio_clone_bioset(bio, gfp_mask, mddev->bio_set);
+}
+EXPORT_SYMBOL_GPL(bio_clone_mddev);
+
+/*
+ * We have a system wide 'event count' that is incremented
+ * on any 'interesting' event, and readers of /proc/mdstat
+ * can use 'poll' or 'select' to find out when the event
+ * count increases.
+ *
+ * Events are:
+ *  start array, stop array, error, add device, remove device,
+ *  start build, activate spare
+ */
+static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
+static atomic_t md_event_count;
+void md_new_event(struct mddev *mddev)
+{
+	atomic_inc(&md_event_count);
+	wake_up(&md_event_waiters);
+}
+EXPORT_SYMBOL_GPL(md_new_event);
+
+/* Alternate version that can be called from interrupts
+ * when calling sysfs_notify isn't needed.
+ */
+static void md_new_event_inintr(struct mddev *mddev)
+{
+	atomic_inc(&md_event_count);
+	wake_up(&md_event_waiters);
+}
+
+/*
+ * Enables to iterate over all existing md arrays
+ * all_mddevs_lock protects this list.
+ */
+static LIST_HEAD(all_mddevs);
+static DEFINE_SPINLOCK(all_mddevs_lock);
+
+/*
+ * iterates through all used mddevs in the system.
+ * We take care to grab the all_mddevs_lock whenever navigating
+ * the list, and to always hold a refcount when unlocked.
+ * Any code which breaks out of this loop while own
+ * a reference to the current mddev and must mddev_put it.
+ */
+#define for_each_mddev(_mddev,_tmp)					\
+									\
+	for (({ spin_lock(&all_mddevs_lock);				\
+		_tmp = all_mddevs.next;					\
+		_mddev = NULL;});					\
+	     ({ if (_tmp != &all_mddevs)				\
+			mddev_get(list_entry(_tmp, struct mddev, all_mddevs));\
+		spin_unlock(&all_mddevs_lock);				\
+		if (_mddev) mddev_put(_mddev);				\
+		_mddev = list_entry(_tmp, struct mddev, all_mddevs);	\
+		_tmp != &all_mddevs;});					\
+	     ({ spin_lock(&all_mddevs_lock);				\
+		_tmp = _tmp->next;})					\
+		)
+
+/* Rather than calling directly into the personality make_request function,
+ * IO requests come here first so that we can check if the device is
+ * being suspended pending a reconfiguration.
+ * We hold a refcount over the call to ->make_request.  By the time that
+ * call has finished, the bio has been linked into some internal structure
+ * and so is visible to ->quiesce(), so we don't need the refcount any more.
+ */
+static void md_make_request(struct request_queue *q, struct bio *bio)
+{
+	const int rw = bio_data_dir(bio);
+	struct mddev *mddev = q->queuedata;
+	unsigned int sectors;
+	int cpu;
+
+	if (mddev == NULL || mddev->pers == NULL
+	    || !mddev->ready) {
+		bio_io_error(bio);
+		return;
+	}
+	if (mddev->ro == 1 && unlikely(rw == WRITE)) {
+		bio_endio(bio, bio_sectors(bio) == 0 ? 0 : -EROFS);
+		return;
+	}
+	smp_rmb(); /* Ensure implications of  'active' are visible */
+	rcu_read_lock();
+	if (mddev->suspended) {
+		DEFINE_WAIT(__wait);
+		for (;;) {
+			prepare_to_wait(&mddev->sb_wait, &__wait,
+					TASK_UNINTERRUPTIBLE);
+			if (!mddev->suspended)
+				break;
+			rcu_read_unlock();
+			schedule();
+			rcu_read_lock();
+		}
+		finish_wait(&mddev->sb_wait, &__wait);
+	}
+	atomic_inc(&mddev->active_io);
+	rcu_read_unlock();
+
+	/*
+	 * save the sectors now since our bio can
+	 * go away inside make_request
+	 */
+	sectors = bio_sectors(bio);
+	mddev->pers->make_request(mddev, bio);
+
+	cpu = part_stat_lock();
+	part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
+	part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);
+	part_stat_unlock();
+
+	if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
+		wake_up(&mddev->sb_wait);
+}
+
+/* mddev_suspend makes sure no new requests are submitted
+ * to the device, and that any requests that have been submitted
+ * are completely handled.
+ * Once mddev_detach() is called and completes, the module will be
+ * completely unused.
+ */
+void mddev_suspend(struct mddev *mddev)
+{
+	BUG_ON(mddev->suspended);
+	mddev->suspended = 1;
+	synchronize_rcu();
+	wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
+	mddev->pers->quiesce(mddev, 1);
+
+	del_timer_sync(&mddev->safemode_timer);
+}
+EXPORT_SYMBOL_GPL(mddev_suspend);
+
+void mddev_resume(struct mddev *mddev)
+{
+	mddev->suspended = 0;
+	wake_up(&mddev->sb_wait);
+	mddev->pers->quiesce(mddev, 0);
+
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
+}
+EXPORT_SYMBOL_GPL(mddev_resume);
+
+int mddev_congested(struct mddev *mddev, int bits)
+{
+	struct md_personality *pers = mddev->pers;
+	int ret = 0;
+
+	rcu_read_lock();
+	if (mddev->suspended)
+		ret = 1;
+	else if (pers && pers->congested)
+		ret = pers->congested(mddev, bits);
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mddev_congested);
+static int md_congested(void *data, int bits)
+{
+	struct mddev *mddev = data;
+	return mddev_congested(mddev, bits);
+}
+
+static int md_mergeable_bvec(struct request_queue *q,
+			     struct bvec_merge_data *bvm,
+			     struct bio_vec *biovec)
+{
+	struct mddev *mddev = q->queuedata;
+	int ret;
+	rcu_read_lock();
+	if (mddev->suspended) {
+		/* Must always allow one vec */
+		if (bvm->bi_size == 0)
+			ret = biovec->bv_len;
+		else
+			ret = 0;
+	} else {
+		struct md_personality *pers = mddev->pers;
+		if (pers && pers->mergeable_bvec)
+			ret = pers->mergeable_bvec(mddev, bvm, biovec);
+		else
+			ret = biovec->bv_len;
+	}
+	rcu_read_unlock();
+	return ret;
+}
+/*
+ * Generic flush handling for md
+ */
+
+static void md_end_flush(struct bio *bio, int err)
+{
+	struct md_rdev *rdev = bio->bi_private;
+	struct mddev *mddev = rdev->mddev;
+
+	rdev_dec_pending(rdev, mddev);
+
+	if (atomic_dec_and_test(&mddev->flush_pending)) {
+		/* The pre-request flush has finished */
+		queue_work(md_wq, &mddev->flush_work);
+	}
+	bio_put(bio);
+}
+
+static void md_submit_flush_data(struct work_struct *ws);
+
+static void submit_flushes(struct work_struct *ws)
+{
+	struct mddev *mddev = container_of(ws, struct mddev, flush_work);
+	struct md_rdev *rdev;
+
+	INIT_WORK(&mddev->flush_work, md_submit_flush_data);
+	atomic_set(&mddev->flush_pending, 1);
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev)
+		if (rdev->raid_disk >= 0 &&
+		    !test_bit(Faulty, &rdev->flags)) {
+			/* Take two references, one is dropped
+			 * when request finishes, one after
+			 * we reclaim rcu_read_lock
+			 */
+			struct bio *bi;
+			atomic_inc(&rdev->nr_pending);
+			atomic_inc(&rdev->nr_pending);
+			rcu_read_unlock();
+			bi = bio_alloc_mddev(GFP_NOIO, 0, mddev);
+			bi->bi_end_io = md_end_flush;
+			bi->bi_private = rdev;
+			bi->bi_bdev = rdev->bdev;
+			atomic_inc(&mddev->flush_pending);
+			submit_bio(WRITE_FLUSH, bi);
+			rcu_read_lock();
+			rdev_dec_pending(rdev, mddev);
+		}
+	rcu_read_unlock();
+	if (atomic_dec_and_test(&mddev->flush_pending))
+		queue_work(md_wq, &mddev->flush_work);
+}
+
+static void md_submit_flush_data(struct work_struct *ws)
+{
+	struct mddev *mddev = container_of(ws, struct mddev, flush_work);
+	struct bio *bio = mddev->flush_bio;
+
+	if (bio->bi_iter.bi_size == 0)
+		/* an empty barrier - all done */
+		bio_endio(bio, 0);
+	else {
+		bio->bi_rw &= ~REQ_FLUSH;
+		mddev->pers->make_request(mddev, bio);
+	}
+
+	mddev->flush_bio = NULL;
+	wake_up(&mddev->sb_wait);
+}
+
+void md_flush_request(struct mddev *mddev, struct bio *bio)
+{
+	spin_lock_irq(&mddev->lock);
+	wait_event_lock_irq(mddev->sb_wait,
+			    !mddev->flush_bio,
+			    mddev->lock);
+	mddev->flush_bio = bio;
+	spin_unlock_irq(&mddev->lock);
+
+	INIT_WORK(&mddev->flush_work, submit_flushes);
+	queue_work(md_wq, &mddev->flush_work);
+}
+EXPORT_SYMBOL(md_flush_request);
+
+void md_unplug(struct blk_plug_cb *cb, bool from_schedule)
+{
+	struct mddev *mddev = cb->data;
+	md_wakeup_thread(mddev->thread);
+	kfree(cb);
+}
+EXPORT_SYMBOL(md_unplug);
+
+static inline struct mddev *mddev_get(struct mddev *mddev)
+{
+	atomic_inc(&mddev->active);
+	return mddev;
+}
+
+static void mddev_delayed_delete(struct work_struct *ws);
+
+static void mddev_put(struct mddev *mddev)
+{
+	struct bio_set *bs = NULL;
+
+	if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
+		return;
+	if (!mddev->raid_disks && list_empty(&mddev->disks) &&
+	    mddev->ctime == 0 && !mddev->hold_active) {
+		/* Array is not configured at all, and not held active,
+		 * so destroy it */
+		list_del_init(&mddev->all_mddevs);
+		bs = mddev->bio_set;
+		mddev->bio_set = NULL;
+		if (mddev->gendisk) {
+			/* We did a probe so need to clean up.  Call
+			 * queue_work inside the spinlock so that
+			 * flush_workqueue() after mddev_find will
+			 * succeed in waiting for the work to be done.
+			 */
+			INIT_WORK(&mddev->del_work, mddev_delayed_delete);
+			queue_work(md_misc_wq, &mddev->del_work);
+		} else
+			kfree(mddev);
+	}
+	spin_unlock(&all_mddevs_lock);
+	if (bs)
+		bioset_free(bs);
+}
+
+void mddev_init(struct mddev *mddev)
+{
+	mutex_init(&mddev->open_mutex);
+	mutex_init(&mddev->reconfig_mutex);
+	mutex_init(&mddev->bitmap_info.mutex);
+	INIT_LIST_HEAD(&mddev->disks);
+	INIT_LIST_HEAD(&mddev->all_mddevs);
+	init_timer(&mddev->safemode_timer);
+	atomic_set(&mddev->active, 1);
+	atomic_set(&mddev->openers, 0);
+	atomic_set(&mddev->active_io, 0);
+	spin_lock_init(&mddev->lock);
+	atomic_set(&mddev->flush_pending, 0);
+	init_waitqueue_head(&mddev->sb_wait);
+	init_waitqueue_head(&mddev->recovery_wait);
+	mddev->reshape_position = MaxSector;
+	mddev->reshape_backwards = 0;
+	mddev->last_sync_action = "none";
+	mddev->resync_min = 0;
+	mddev->resync_max = MaxSector;
+	mddev->level = LEVEL_NONE;
+}
+EXPORT_SYMBOL_GPL(mddev_init);
+
+static struct mddev *mddev_find(dev_t unit)
+{
+	struct mddev *mddev, *new = NULL;
+
+	if (unit && MAJOR(unit) != MD_MAJOR)
+		unit &= ~((1<<MdpMinorShift)-1);
+
+ retry:
+	spin_lock(&all_mddevs_lock);
+
+	if (unit) {
+		list_for_each_entry(mddev, &all_mddevs, all_mddevs)
+			if (mddev->unit == unit) {
+				mddev_get(mddev);
+				spin_unlock(&all_mddevs_lock);
+				kfree(new);
+				return mddev;
+			}
+
+		if (new) {
+			list_add(&new->all_mddevs, &all_mddevs);
+			spin_unlock(&all_mddevs_lock);
+			new->hold_active = UNTIL_IOCTL;
+			return new;
+		}
+	} else if (new) {
+		/* find an unused unit number */
+		static int next_minor = 512;
+		int start = next_minor;
+		int is_free = 0;
+		int dev = 0;
+		while (!is_free) {
+			dev = MKDEV(MD_MAJOR, next_minor);
+			next_minor++;
+			if (next_minor > MINORMASK)
+				next_minor = 0;
+			if (next_minor == start) {
+				/* Oh dear, all in use. */
+				spin_unlock(&all_mddevs_lock);
+				kfree(new);
+				return NULL;
+			}
+
+			is_free = 1;
+			list_for_each_entry(mddev, &all_mddevs, all_mddevs)
+				if (mddev->unit == dev) {
+					is_free = 0;
+					break;
+				}
+		}
+		new->unit = dev;
+		new->md_minor = MINOR(dev);
+		new->hold_active = UNTIL_STOP;
+		list_add(&new->all_mddevs, &all_mddevs);
+		spin_unlock(&all_mddevs_lock);
+		return new;
+	}
+	spin_unlock(&all_mddevs_lock);
+
+	new = kzalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	new->unit = unit;
+	if (MAJOR(unit) == MD_MAJOR)
+		new->md_minor = MINOR(unit);
+	else
+		new->md_minor = MINOR(unit) >> MdpMinorShift;
+
+	mddev_init(new);
+
+	goto retry;
+}
+
+static struct attribute_group md_redundancy_group;
+
+void mddev_unlock(struct mddev *mddev)
+{
+	if (mddev->to_remove) {
+		/* These cannot be removed under reconfig_mutex as
+		 * an access to the files will try to take reconfig_mutex
+		 * while holding the file unremovable, which leads to
+		 * a deadlock.
+		 * So hold set sysfs_active while the remove in happeing,
+		 * and anything else which might set ->to_remove or my
+		 * otherwise change the sysfs namespace will fail with
+		 * -EBUSY if sysfs_active is still set.
+		 * We set sysfs_active under reconfig_mutex and elsewhere
+		 * test it under the same mutex to ensure its correct value
+		 * is seen.
+		 */
+		struct attribute_group *to_remove = mddev->to_remove;
+		mddev->to_remove = NULL;
+		mddev->sysfs_active = 1;
+		mutex_unlock(&mddev->reconfig_mutex);
+
+		if (mddev->kobj.sd) {
+			if (to_remove != &md_redundancy_group)
+				sysfs_remove_group(&mddev->kobj, to_remove);
+			if (mddev->pers == NULL ||
+			    mddev->pers->sync_request == NULL) {
+				sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
+				if (mddev->sysfs_action)
+					sysfs_put(mddev->sysfs_action);
+				mddev->sysfs_action = NULL;
+			}
+		}
+		mddev->sysfs_active = 0;
+	} else
+		mutex_unlock(&mddev->reconfig_mutex);
+
+	/* As we've dropped the mutex we need a spinlock to
+	 * make sure the thread doesn't disappear
+	 */
+	spin_lock(&pers_lock);
+	md_wakeup_thread(mddev->thread);
+	spin_unlock(&pers_lock);
+}
+EXPORT_SYMBOL_GPL(mddev_unlock);
+
+struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr)
+{
+	struct md_rdev *rdev;
+
+	rdev_for_each_rcu(rdev, mddev)
+		if (rdev->desc_nr == nr)
+			return rdev;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(md_find_rdev_nr_rcu);
+
+static struct md_rdev *find_rdev(struct mddev *mddev, dev_t dev)
+{
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, mddev)
+		if (rdev->bdev->bd_dev == dev)
+			return rdev;
+
+	return NULL;
+}
+
+static struct md_rdev *find_rdev_rcu(struct mddev *mddev, dev_t dev)
+{
+	struct md_rdev *rdev;
+
+	rdev_for_each_rcu(rdev, mddev)
+		if (rdev->bdev->bd_dev == dev)
+			return rdev;
+
+	return NULL;
+}
+
+static struct md_personality *find_pers(int level, char *clevel)
+{
+	struct md_personality *pers;
+	list_for_each_entry(pers, &pers_list, list) {
+		if (level != LEVEL_NONE && pers->level == level)
+			return pers;
+		if (strcmp(pers->name, clevel)==0)
+			return pers;
+	}
+	return NULL;
+}
+
+/* return the offset of the super block in 512byte sectors */
+static inline sector_t calc_dev_sboffset(struct md_rdev *rdev)
+{
+	sector_t num_sectors = i_size_read(rdev->bdev->bd_inode) / 512;
+	return MD_NEW_SIZE_SECTORS(num_sectors);
+}
+
+static int alloc_disk_sb(struct md_rdev *rdev)
+{
+	rdev->sb_page = alloc_page(GFP_KERNEL);
+	if (!rdev->sb_page) {
+		printk(KERN_ALERT "md: out of memory.\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+void md_rdev_clear(struct md_rdev *rdev)
+{
+	if (rdev->sb_page) {
+		put_page(rdev->sb_page);
+		rdev->sb_loaded = 0;
+		rdev->sb_page = NULL;
+		rdev->sb_start = 0;
+		rdev->sectors = 0;
+	}
+	if (rdev->bb_page) {
+		put_page(rdev->bb_page);
+		rdev->bb_page = NULL;
+	}
+	kfree(rdev->badblocks.page);
+	rdev->badblocks.page = NULL;
+}
+EXPORT_SYMBOL_GPL(md_rdev_clear);
+
+static void super_written(struct bio *bio, int error)
+{
+	struct md_rdev *rdev = bio->bi_private;
+	struct mddev *mddev = rdev->mddev;
+
+	if (error || !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
+		printk("md: super_written gets error=%d, uptodate=%d\n",
+		       error, test_bit(BIO_UPTODATE, &bio->bi_flags));
+		WARN_ON(test_bit(BIO_UPTODATE, &bio->bi_flags));
+		md_error(mddev, rdev);
+	}
+
+	if (atomic_dec_and_test(&mddev->pending_writes))
+		wake_up(&mddev->sb_wait);
+	bio_put(bio);
+}
+
+void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
+		   sector_t sector, int size, struct page *page)
+{
+	/* write first size bytes of page to sector of rdev
+	 * Increment mddev->pending_writes before returning
+	 * and decrement it on completion, waking up sb_wait
+	 * if zero is reached.
+	 * If an error occurred, call md_error
+	 */
+	struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, mddev);
+
+	bio->bi_bdev = rdev->meta_bdev ? rdev->meta_bdev : rdev->bdev;
+	bio->bi_iter.bi_sector = sector;
+	bio_add_page(bio, page, size, 0);
+	bio->bi_private = rdev;
+	bio->bi_end_io = super_written;
+
+	atomic_inc(&mddev->pending_writes);
+	submit_bio(WRITE_FLUSH_FUA, bio);
+}
+
+void md_super_wait(struct mddev *mddev)
+{
+	/* wait for all superblock writes that were scheduled to complete */
+	wait_event(mddev->sb_wait, atomic_read(&mddev->pending_writes)==0);
+}
+
+int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
+		 struct page *page, int rw, bool metadata_op)
+{
+	struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, rdev->mddev);
+	int ret;
+
+	bio->bi_bdev = (metadata_op && rdev->meta_bdev) ?
+		rdev->meta_bdev : rdev->bdev;
+	if (metadata_op)
+		bio->bi_iter.bi_sector = sector + rdev->sb_start;
+	else if (rdev->mddev->reshape_position != MaxSector &&
+		 (rdev->mddev->reshape_backwards ==
+		  (sector >= rdev->mddev->reshape_position)))
+		bio->bi_iter.bi_sector = sector + rdev->new_data_offset;
+	else
+		bio->bi_iter.bi_sector = sector + rdev->data_offset;
+	bio_add_page(bio, page, size, 0);
+	submit_bio_wait(rw, bio);
+
+	ret = test_bit(BIO_UPTODATE, &bio->bi_flags);
+	bio_put(bio);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sync_page_io);
+
+static int read_disk_sb(struct md_rdev *rdev, int size)
+{
+	char b[BDEVNAME_SIZE];
+
+	if (rdev->sb_loaded)
+		return 0;
+
+	if (!sync_page_io(rdev, 0, size, rdev->sb_page, READ, true))
+		goto fail;
+	rdev->sb_loaded = 1;
+	return 0;
+
+fail:
+	printk(KERN_WARNING "md: disabled device %s, could not read superblock.\n",
+		bdevname(rdev->bdev,b));
+	return -EINVAL;
+}
+
+static int uuid_equal(mdp_super_t *sb1, mdp_super_t *sb2)
+{
+	return	sb1->set_uuid0 == sb2->set_uuid0 &&
+		sb1->set_uuid1 == sb2->set_uuid1 &&
+		sb1->set_uuid2 == sb2->set_uuid2 &&
+		sb1->set_uuid3 == sb2->set_uuid3;
+}
+
+static int sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
+{
+	int ret;
+	mdp_super_t *tmp1, *tmp2;
+
+	tmp1 = kmalloc(sizeof(*tmp1),GFP_KERNEL);
+	tmp2 = kmalloc(sizeof(*tmp2),GFP_KERNEL);
+
+	if (!tmp1 || !tmp2) {
+		ret = 0;
+		printk(KERN_INFO "md.c sb_equal(): failed to allocate memory!\n");
+		goto abort;
+	}
+
+	*tmp1 = *sb1;
+	*tmp2 = *sb2;
+
+	/*
+	 * nr_disks is not constant
+	 */
+	tmp1->nr_disks = 0;
+	tmp2->nr_disks = 0;
+
+	ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
+abort:
+	kfree(tmp1);
+	kfree(tmp2);
+	return ret;
+}
+
+static u32 md_csum_fold(u32 csum)
+{
+	csum = (csum & 0xffff) + (csum >> 16);
+	return (csum & 0xffff) + (csum >> 16);
+}
+
+static unsigned int calc_sb_csum(mdp_super_t *sb)
+{
+	u64 newcsum = 0;
+	u32 *sb32 = (u32*)sb;
+	int i;
+	unsigned int disk_csum, csum;
+
+	disk_csum = sb->sb_csum;
+	sb->sb_csum = 0;
+
+	for (i = 0; i < MD_SB_BYTES/4 ; i++)
+		newcsum += sb32[i];
+	csum = (newcsum & 0xffffffff) + (newcsum>>32);
+
+#ifdef CONFIG_ALPHA
+	/* This used to use csum_partial, which was wrong for several
+	 * reasons including that different results are returned on
+	 * different architectures.  It isn't critical that we get exactly
+	 * the same return value as before (we always csum_fold before
+	 * testing, and that removes any differences).  However as we
+	 * know that csum_partial always returned a 16bit value on
+	 * alphas, do a fold to maximise conformity to previous behaviour.
+	 */
+	sb->sb_csum = md_csum_fold(disk_csum);
+#else
+	sb->sb_csum = disk_csum;
+#endif
+	return csum;
+}
+
+/*
+ * Handle superblock details.
+ * We want to be able to handle multiple superblock formats
+ * so we have a common interface to them all, and an array of
+ * different handlers.
+ * We rely on user-space to write the initial superblock, and support
+ * reading and updating of superblocks.
+ * Interface methods are:
+ *   int load_super(struct md_rdev *dev, struct md_rdev *refdev, int minor_version)
+ *      loads and validates a superblock on dev.
+ *      if refdev != NULL, compare superblocks on both devices
+ *    Return:
+ *      0 - dev has a superblock that is compatible with refdev
+ *      1 - dev has a superblock that is compatible and newer than refdev
+ *          so dev should be used as the refdev in future
+ *     -EINVAL superblock incompatible or invalid
+ *     -othererror e.g. -EIO
+ *
+ *   int validate_super(struct mddev *mddev, struct md_rdev *dev)
+ *      Verify that dev is acceptable into mddev.
+ *       The first time, mddev->raid_disks will be 0, and data from
+ *       dev should be merged in.  Subsequent calls check that dev
+ *       is new enough.  Return 0 or -EINVAL
+ *
+ *   void sync_super(struct mddev *mddev, struct md_rdev *dev)
+ *     Update the superblock for rdev with data in mddev
+ *     This does not write to disc.
+ *
+ */
+
+struct super_type  {
+	char		    *name;
+	struct module	    *owner;
+	int		    (*load_super)(struct md_rdev *rdev,
+					  struct md_rdev *refdev,
+					  int minor_version);
+	int		    (*validate_super)(struct mddev *mddev,
+					      struct md_rdev *rdev);
+	void		    (*sync_super)(struct mddev *mddev,
+					  struct md_rdev *rdev);
+	unsigned long long  (*rdev_size_change)(struct md_rdev *rdev,
+						sector_t num_sectors);
+	int		    (*allow_new_offset)(struct md_rdev *rdev,
+						unsigned long long new_offset);
+};
+
+/*
+ * Check that the given mddev has no bitmap.
+ *
+ * This function is called from the run method of all personalities that do not
+ * support bitmaps. It prints an error message and returns non-zero if mddev
+ * has a bitmap. Otherwise, it returns 0.
+ *
+ */
+int md_check_no_bitmap(struct mddev *mddev)
+{
+	if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
+		return 0;
+	printk(KERN_ERR "%s: bitmaps are not supported for %s\n",
+		mdname(mddev), mddev->pers->name);
+	return 1;
+}
+EXPORT_SYMBOL(md_check_no_bitmap);
+
+/*
+ * load_super for 0.90.0
+ */
+static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
+{
+	char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
+	mdp_super_t *sb;
+	int ret;
+
+	/*
+	 * Calculate the position of the superblock (512byte sectors),
+	 * it's at the end of the disk.
+	 *
+	 * It also happens to be a multiple of 4Kb.
+	 */
+	rdev->sb_start = calc_dev_sboffset(rdev);
+
+	ret = read_disk_sb(rdev, MD_SB_BYTES);
+	if (ret) return ret;
+
+	ret = -EINVAL;
+
+	bdevname(rdev->bdev, b);
+	sb = page_address(rdev->sb_page);
+
+	if (sb->md_magic != MD_SB_MAGIC) {
+		printk(KERN_ERR "md: invalid raid superblock magic on %s\n",
+		       b);
+		goto abort;
+	}
+
+	if (sb->major_version != 0 ||
+	    sb->minor_version < 90 ||
+	    sb->minor_version > 91) {
+		printk(KERN_WARNING "Bad version number %d.%d on %s\n",
+			sb->major_version, sb->minor_version,
+			b);
+		goto abort;
+	}
+
+	if (sb->raid_disks <= 0)
+		goto abort;
+
+	if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
+		printk(KERN_WARNING "md: invalid superblock checksum on %s\n",
+			b);
+		goto abort;
+	}
+
+	rdev->preferred_minor = sb->md_minor;
+	rdev->data_offset = 0;
+	rdev->new_data_offset = 0;
+	rdev->sb_size = MD_SB_BYTES;
+	rdev->badblocks.shift = -1;
+
+	if (sb->level == LEVEL_MULTIPATH)
+		rdev->desc_nr = -1;
+	else
+		rdev->desc_nr = sb->this_disk.number;
+
+	if (!refdev) {
+		ret = 1;
+	} else {
+		__u64 ev1, ev2;
+		mdp_super_t *refsb = page_address(refdev->sb_page);
+		if (!uuid_equal(refsb, sb)) {
+			printk(KERN_WARNING "md: %s has different UUID to %s\n",
+				b, bdevname(refdev->bdev,b2));
+			goto abort;
+		}
+		if (!sb_equal(refsb, sb)) {
+			printk(KERN_WARNING "md: %s has same UUID"
+			       " but different superblock to %s\n",
+			       b, bdevname(refdev->bdev, b2));
+			goto abort;
+		}
+		ev1 = md_event(sb);
+		ev2 = md_event(refsb);
+		if (ev1 > ev2)
+			ret = 1;
+		else
+			ret = 0;
+	}
+	rdev->sectors = rdev->sb_start;
+	/* Limit to 4TB as metadata cannot record more than that.
+	 * (not needed for Linear and RAID0 as metadata doesn't
+	 * record this size)
+	 */
+	if (rdev->sectors >= (2ULL << 32) && sb->level >= 1)
+		rdev->sectors = (2ULL << 32) - 2;
+
+	if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >= 1)
+		/* "this cannot possibly happen" ... */
+		ret = -EINVAL;
+
+ abort:
+	return ret;
+}
+
+/*
+ * validate_super for 0.90.0
+ */
+static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev)
+{
+	mdp_disk_t *desc;
+	mdp_super_t *sb = page_address(rdev->sb_page);
+	__u64 ev1 = md_event(sb);
+
+	rdev->raid_disk = -1;
+	clear_bit(Faulty, &rdev->flags);
+	clear_bit(In_sync, &rdev->flags);
+	clear_bit(Bitmap_sync, &rdev->flags);
+	clear_bit(WriteMostly, &rdev->flags);
+
+	if (mddev->raid_disks == 0) {
+		mddev->major_version = 0;
+		mddev->minor_version = sb->minor_version;
+		mddev->patch_version = sb->patch_version;
+		mddev->external = 0;
+		mddev->chunk_sectors = sb->chunk_size >> 9;
+		mddev->ctime = sb->ctime;
+		mddev->utime = sb->utime;
+		mddev->level = sb->level;
+		mddev->clevel[0] = 0;
+		mddev->layout = sb->layout;
+		mddev->raid_disks = sb->raid_disks;
+		mddev->dev_sectors = ((sector_t)sb->size) * 2;
+		mddev->events = ev1;
+		mddev->bitmap_info.offset = 0;
+		mddev->bitmap_info.space = 0;
+		/* bitmap can use 60 K after the 4K superblocks */
+		mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
+		mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
+		mddev->reshape_backwards = 0;
+
+		if (mddev->minor_version >= 91) {
+			mddev->reshape_position = sb->reshape_position;
+			mddev->delta_disks = sb->delta_disks;
+			mddev->new_level = sb->new_level;
+			mddev->new_layout = sb->new_layout;
+			mddev->new_chunk_sectors = sb->new_chunk >> 9;
+			if (mddev->delta_disks < 0)
+				mddev->reshape_backwards = 1;
+		} else {
+			mddev->reshape_position = MaxSector;
+			mddev->delta_disks = 0;
+			mddev->new_level = mddev->level;
+			mddev->new_layout = mddev->layout;
+			mddev->new_chunk_sectors = mddev->chunk_sectors;
+		}
+
+		if (sb->state & (1<<MD_SB_CLEAN))
+			mddev->recovery_cp = MaxSector;
+		else {
+			if (sb->events_hi == sb->cp_events_hi &&
+				sb->events_lo == sb->cp_events_lo) {
+				mddev->recovery_cp = sb->recovery_cp;
+			} else
+				mddev->recovery_cp = 0;
+		}
+
+		memcpy(mddev->uuid+0, &sb->set_uuid0, 4);
+		memcpy(mddev->uuid+4, &sb->set_uuid1, 4);
+		memcpy(mddev->uuid+8, &sb->set_uuid2, 4);
+		memcpy(mddev->uuid+12,&sb->set_uuid3, 4);
+
+		mddev->max_disks = MD_SB_DISKS;
+
+		if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
+		    mddev->bitmap_info.file == NULL) {
+			mddev->bitmap_info.offset =
+				mddev->bitmap_info.default_offset;
+			mddev->bitmap_info.space =
+				mddev->bitmap_info.default_space;
+		}
+
+	} else if (mddev->pers == NULL) {
+		/* Insist on good event counter while assembling, except
+		 * for spares (which don't need an event count) */
+		++ev1;
+		if (sb->disks[rdev->desc_nr].state & (
+			    (1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
+			if (ev1 < mddev->events)
+				return -EINVAL;
+	} else if (mddev->bitmap) {
+		/* if adding to array with a bitmap, then we can accept an
+		 * older device ... but not too old.
+		 */
+		if (ev1 < mddev->bitmap->events_cleared)
+			return 0;
+		if (ev1 < mddev->events)
+			set_bit(Bitmap_sync, &rdev->flags);
+	} else {
+		if (ev1 < mddev->events)
+			/* just a hot-add of a new device, leave raid_disk at -1 */
+			return 0;
+	}
+
+	if (mddev->level != LEVEL_MULTIPATH) {
+		desc = sb->disks + rdev->desc_nr;
+
+		if (desc->state & (1<<MD_DISK_FAULTY))
+			set_bit(Faulty, &rdev->flags);
+		else if (desc->state & (1<<MD_DISK_SYNC) /* &&
+			    desc->raid_disk < mddev->raid_disks */) {
+			set_bit(In_sync, &rdev->flags);
+			rdev->raid_disk = desc->raid_disk;
+			rdev->saved_raid_disk = desc->raid_disk;
+		} else if (desc->state & (1<<MD_DISK_ACTIVE)) {
+			/* active but not in sync implies recovery up to
+			 * reshape position.  We don't know exactly where
+			 * that is, so set to zero for now */
+			if (mddev->minor_version >= 91) {
+				rdev->recovery_offset = 0;
+				rdev->raid_disk = desc->raid_disk;
+			}
+		}
+		if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
+			set_bit(WriteMostly, &rdev->flags);
+	} else /* MULTIPATH are always insync */
+		set_bit(In_sync, &rdev->flags);
+	return 0;
+}
+
+/*
+ * sync_super for 0.90.0
+ */
+static void super_90_sync(struct mddev *mddev, struct md_rdev *rdev)
+{
+	mdp_super_t *sb;
+	struct md_rdev *rdev2;
+	int next_spare = mddev->raid_disks;
+
+	/* make rdev->sb match mddev data..
+	 *
+	 * 1/ zero out disks
+	 * 2/ Add info for each disk, keeping track of highest desc_nr (next_spare);
+	 * 3/ any empty disks < next_spare become removed
+	 *
+	 * disks[0] gets initialised to REMOVED because
+	 * we cannot be sure from other fields if it has
+	 * been initialised or not.
+	 */
+	int i;
+	int active=0, working=0,failed=0,spare=0,nr_disks=0;
+
+	rdev->sb_size = MD_SB_BYTES;
+
+	sb = page_address(rdev->sb_page);
+
+	memset(sb, 0, sizeof(*sb));
+
+	sb->md_magic = MD_SB_MAGIC;
+	sb->major_version = mddev->major_version;
+	sb->patch_version = mddev->patch_version;
+	sb->gvalid_words  = 0; /* ignored */
+	memcpy(&sb->set_uuid0, mddev->uuid+0, 4);
+	memcpy(&sb->set_uuid1, mddev->uuid+4, 4);
+	memcpy(&sb->set_uuid2, mddev->uuid+8, 4);
+	memcpy(&sb->set_uuid3, mddev->uuid+12,4);
+
+	sb->ctime = mddev->ctime;
+	sb->level = mddev->level;
+	sb->size = mddev->dev_sectors / 2;
+	sb->raid_disks = mddev->raid_disks;
+	sb->md_minor = mddev->md_minor;
+	sb->not_persistent = 0;
+	sb->utime = mddev->utime;
+	sb->state = 0;
+	sb->events_hi = (mddev->events>>32);
+	sb->events_lo = (u32)mddev->events;
+
+	if (mddev->reshape_position == MaxSector)
+		sb->minor_version = 90;
+	else {
+		sb->minor_version = 91;
+		sb->reshape_position = mddev->reshape_position;
+		sb->new_level = mddev->new_level;
+		sb->delta_disks = mddev->delta_disks;
+		sb->new_layout = mddev->new_layout;
+		sb->new_chunk = mddev->new_chunk_sectors << 9;
+	}
+	mddev->minor_version = sb->minor_version;
+	if (mddev->in_sync)
+	{
+		sb->recovery_cp = mddev->recovery_cp;
+		sb->cp_events_hi = (mddev->events>>32);
+		sb->cp_events_lo = (u32)mddev->events;
+		if (mddev->recovery_cp == MaxSector)
+			sb->state = (1<< MD_SB_CLEAN);
+	} else
+		sb->recovery_cp = 0;
+
+	sb->layout = mddev->layout;
+	sb->chunk_size = mddev->chunk_sectors << 9;
+
+	if (mddev->bitmap && mddev->bitmap_info.file == NULL)
+		sb->state |= (1<<MD_SB_BITMAP_PRESENT);
+
+	sb->disks[0].state = (1<<MD_DISK_REMOVED);
+	rdev_for_each(rdev2, mddev) {
+		mdp_disk_t *d;
+		int desc_nr;
+		int is_active = test_bit(In_sync, &rdev2->flags);
+
+		if (rdev2->raid_disk >= 0 &&
+		    sb->minor_version >= 91)
+			/* we have nowhere to store the recovery_offset,
+			 * but if it is not below the reshape_position,
+			 * we can piggy-back on that.
+			 */
+			is_active = 1;
+		if (rdev2->raid_disk < 0 ||
+		    test_bit(Faulty, &rdev2->flags))
+			is_active = 0;
+		if (is_active)
+			desc_nr = rdev2->raid_disk;
+		else
+			desc_nr = next_spare++;
+		rdev2->desc_nr = desc_nr;
+		d = &sb->disks[rdev2->desc_nr];
+		nr_disks++;
+		d->number = rdev2->desc_nr;
+		d->major = MAJOR(rdev2->bdev->bd_dev);
+		d->minor = MINOR(rdev2->bdev->bd_dev);
+		if (is_active)
+			d->raid_disk = rdev2->raid_disk;
+		else
+			d->raid_disk = rdev2->desc_nr; /* compatibility */
+		if (test_bit(Faulty, &rdev2->flags))
+			d->state = (1<<MD_DISK_FAULTY);
+		else if (is_active) {
+			d->state = (1<<MD_DISK_ACTIVE);
+			if (test_bit(In_sync, &rdev2->flags))
+				d->state |= (1<<MD_DISK_SYNC);
+			active++;
+			working++;
+		} else {
+			d->state = 0;
+			spare++;
+			working++;
+		}
+		if (test_bit(WriteMostly, &rdev2->flags))
+			d->state |= (1<<MD_DISK_WRITEMOSTLY);
+	}
+	/* now set the "removed" and "faulty" bits on any missing devices */
+	for (i=0 ; i < mddev->raid_disks ; i++) {
+		mdp_disk_t *d = &sb->disks[i];
+		if (d->state == 0 && d->number == 0) {
+			d->number = i;
+			d->raid_disk = i;
+			d->state = (1<<MD_DISK_REMOVED);
+			d->state |= (1<<MD_DISK_FAULTY);
+			failed++;
+		}
+	}
+	sb->nr_disks = nr_disks;
+	sb->active_disks = active;
+	sb->working_disks = working;
+	sb->failed_disks = failed;
+	sb->spare_disks = spare;
+
+	sb->this_disk = sb->disks[rdev->desc_nr];
+	sb->sb_csum = calc_sb_csum(sb);
+}
+
+/*
+ * rdev_size_change for 0.90.0
+ */
+static unsigned long long
+super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
+{
+	if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
+		return 0; /* component must fit device */
+	if (rdev->mddev->bitmap_info.offset)
+		return 0; /* can't move bitmap */
+	rdev->sb_start = calc_dev_sboffset(rdev);
+	if (!num_sectors || num_sectors > rdev->sb_start)
+		num_sectors = rdev->sb_start;
+	/* Limit to 4TB as metadata cannot record more than that.
+	 * 4TB == 2^32 KB, or 2*2^32 sectors.
+	 */
+	if (num_sectors >= (2ULL << 32) && rdev->mddev->level >= 1)
+		num_sectors = (2ULL << 32) - 2;
+	md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
+		       rdev->sb_page);
+	md_super_wait(rdev->mddev);
+	return num_sectors;
+}
+
+static int
+super_90_allow_new_offset(struct md_rdev *rdev, unsigned long long new_offset)
+{
+	/* non-zero offset changes not possible with v0.90 */
+	return new_offset == 0;
+}
+
+/*
+ * version 1 superblock
+ */
+
+static __le32 calc_sb_1_csum(struct mdp_superblock_1 *sb)
+{
+	__le32 disk_csum;
+	u32 csum;
+	unsigned long long newcsum;
+	int size = 256 + le32_to_cpu(sb->max_dev)*2;
+	__le32 *isuper = (__le32*)sb;
+
+	disk_csum = sb->sb_csum;
+	sb->sb_csum = 0;
+	newcsum = 0;
+	for (; size >= 4; size -= 4)
+		newcsum += le32_to_cpu(*isuper++);
+
+	if (size == 2)
+		newcsum += le16_to_cpu(*(__le16*) isuper);
+
+	csum = (newcsum & 0xffffffff) + (newcsum >> 32);
+	sb->sb_csum = disk_csum;
+	return cpu_to_le32(csum);
+}
+
+static int md_set_badblocks(struct badblocks *bb, sector_t s, int sectors,
+			    int acknowledged);
+static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
+{
+	struct mdp_superblock_1 *sb;
+	int ret;
+	sector_t sb_start;
+	sector_t sectors;
+	char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
+	int bmask;
+
+	/*
+	 * Calculate the position of the superblock in 512byte sectors.
+	 * It is always aligned to a 4K boundary and
+	 * depeding on minor_version, it can be:
+	 * 0: At least 8K, but less than 12K, from end of device
+	 * 1: At start of device
+	 * 2: 4K from start of device.
+	 */
+	switch(minor_version) {
+	case 0:
+		sb_start = i_size_read(rdev->bdev->bd_inode) >> 9;
+		sb_start -= 8*2;
+		sb_start &= ~(sector_t)(4*2-1);
+		break;
+	case 1:
+		sb_start = 0;
+		break;
+	case 2:
+		sb_start = 8;
+		break;
+	default:
+		return -EINVAL;
+	}
+	rdev->sb_start = sb_start;
+
+	/* superblock is rarely larger than 1K, but it can be larger,
+	 * and it is safe to read 4k, so we do that
+	 */
+	ret = read_disk_sb(rdev, 4096);
+	if (ret) return ret;
+
+	sb = page_address(rdev->sb_page);
+
+	if (sb->magic != cpu_to_le32(MD_SB_MAGIC) ||
+	    sb->major_version != cpu_to_le32(1) ||
+	    le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
+	    le64_to_cpu(sb->super_offset) != rdev->sb_start ||
+	    (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
+		return -EINVAL;
+
+	if (calc_sb_1_csum(sb) != sb->sb_csum) {
+		printk("md: invalid superblock checksum on %s\n",
+			bdevname(rdev->bdev,b));
+		return -EINVAL;
+	}
+	if (le64_to_cpu(sb->data_size) < 10) {
+		printk("md: data_size too small on %s\n",
+		       bdevname(rdev->bdev,b));
+		return -EINVAL;
+	}
+	if (sb->pad0 ||
+	    sb->pad3[0] ||
+	    memcmp(sb->pad3, sb->pad3+1, sizeof(sb->pad3) - sizeof(sb->pad3[1])))
+		/* Some padding is non-zero, might be a new feature */
+		return -EINVAL;
+
+	rdev->preferred_minor = 0xffff;
+	rdev->data_offset = le64_to_cpu(sb->data_offset);
+	rdev->new_data_offset = rdev->data_offset;
+	if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE) &&
+	    (le32_to_cpu(sb->feature_map) & MD_FEATURE_NEW_OFFSET))
+		rdev->new_data_offset += (s32)le32_to_cpu(sb->new_offset);
+	atomic_set(&rdev->corrected_errors, le32_to_cpu(sb->cnt_corrected_read));
+
+	rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
+	bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
+	if (rdev->sb_size & bmask)
+		rdev->sb_size = (rdev->sb_size | bmask) + 1;
+
+	if (minor_version
+	    && rdev->data_offset < sb_start + (rdev->sb_size/512))
+		return -EINVAL;
+	if (minor_version
+	    && rdev->new_data_offset < sb_start + (rdev->sb_size/512))
+		return -EINVAL;
+
+	if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
+		rdev->desc_nr = -1;
+	else
+		rdev->desc_nr = le32_to_cpu(sb->dev_number);
+
+	if (!rdev->bb_page) {
+		rdev->bb_page = alloc_page(GFP_KERNEL);
+		if (!rdev->bb_page)
+			return -ENOMEM;
+	}
+	if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BAD_BLOCKS) &&
+	    rdev->badblocks.count == 0) {
+		/* need to load the bad block list.
+		 * Currently we limit it to one page.
+		 */
+		s32 offset;
+		sector_t bb_sector;
+		u64 *bbp;
+		int i;
+		int sectors = le16_to_cpu(sb->bblog_size);
+		if (sectors > (PAGE_SIZE / 512))
+			return -EINVAL;
+		offset = le32_to_cpu(sb->bblog_offset);
+		if (offset == 0)
+			return -EINVAL;
+		bb_sector = (long long)offset;
+		if (!sync_page_io(rdev, bb_sector, sectors << 9,
+				  rdev->bb_page, READ, true))
+			return -EIO;
+		bbp = (u64 *)page_address(rdev->bb_page);
+		rdev->badblocks.shift = sb->bblog_shift;
+		for (i = 0 ; i < (sectors << (9-3)) ; i++, bbp++) {
+			u64 bb = le64_to_cpu(*bbp);
+			int count = bb & (0x3ff);
+			u64 sector = bb >> 10;
+			sector <<= sb->bblog_shift;
+			count <<= sb->bblog_shift;
+			if (bb + 1 == 0)
+				break;
+			if (md_set_badblocks(&rdev->badblocks,
+					     sector, count, 1) == 0)
+				return -EINVAL;
+		}
+	} else if (sb->bblog_offset != 0)
+		rdev->badblocks.shift = 0;
+
+	if (!refdev) {
+		ret = 1;
+	} else {
+		__u64 ev1, ev2;
+		struct mdp_superblock_1 *refsb = page_address(refdev->sb_page);
+
+		if (memcmp(sb->set_uuid, refsb->set_uuid, 16) != 0 ||
+		    sb->level != refsb->level ||
+		    sb->layout != refsb->layout ||
+		    sb->chunksize != refsb->chunksize) {
+			printk(KERN_WARNING "md: %s has strangely different"
+				" superblock to %s\n",
+				bdevname(rdev->bdev,b),
+				bdevname(refdev->bdev,b2));
+			return -EINVAL;
+		}
+		ev1 = le64_to_cpu(sb->events);
+		ev2 = le64_to_cpu(refsb->events);
+
+		if (ev1 > ev2)
+			ret = 1;
+		else
+			ret = 0;
+	}
+	if (minor_version) {
+		sectors = (i_size_read(rdev->bdev->bd_inode) >> 9);
+		sectors -= rdev->data_offset;
+	} else
+		sectors = rdev->sb_start;
+	if (sectors < le64_to_cpu(sb->data_size))
+		return -EINVAL;
+	rdev->sectors = le64_to_cpu(sb->data_size);
+	return ret;
+}
+
+static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
+{
+	struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
+	__u64 ev1 = le64_to_cpu(sb->events);
+
+	rdev->raid_disk = -1;
+	clear_bit(Faulty, &rdev->flags);
+	clear_bit(In_sync, &rdev->flags);
+	clear_bit(Bitmap_sync, &rdev->flags);
+	clear_bit(WriteMostly, &rdev->flags);
+
+	if (mddev->raid_disks == 0) {
+		mddev->major_version = 1;
+		mddev->patch_version = 0;
+		mddev->external = 0;
+		mddev->chunk_sectors = le32_to_cpu(sb->chunksize);
+		mddev->ctime = le64_to_cpu(sb->ctime) & ((1ULL << 32)-1);
+		mddev->utime = le64_to_cpu(sb->utime) & ((1ULL << 32)-1);
+		mddev->level = le32_to_cpu(sb->level);
+		mddev->clevel[0] = 0;
+		mddev->layout = le32_to_cpu(sb->layout);
+		mddev->raid_disks = le32_to_cpu(sb->raid_disks);
+		mddev->dev_sectors = le64_to_cpu(sb->size);
+		mddev->events = ev1;
+		mddev->bitmap_info.offset = 0;
+		mddev->bitmap_info.space = 0;
+		/* Default location for bitmap is 1K after superblock
+		 * using 3K - total of 4K
+		 */
+		mddev->bitmap_info.default_offset = 1024 >> 9;
+		mddev->bitmap_info.default_space = (4096-1024) >> 9;
+		mddev->reshape_backwards = 0;
+
+		mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
+		memcpy(mddev->uuid, sb->set_uuid, 16);
+
+		mddev->max_disks =  (4096-256)/2;
+
+		if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
+		    mddev->bitmap_info.file == NULL) {
+			mddev->bitmap_info.offset =
+				(__s32)le32_to_cpu(sb->bitmap_offset);
+			/* Metadata doesn't record how much space is available.
+			 * For 1.0, we assume we can use up to the superblock
+			 * if before, else to 4K beyond superblock.
+			 * For others, assume no change is possible.
+			 */
+			if (mddev->minor_version > 0)
+				mddev->bitmap_info.space = 0;
+			else if (mddev->bitmap_info.offset > 0)
+				mddev->bitmap_info.space =
+					8 - mddev->bitmap_info.offset;
+			else
+				mddev->bitmap_info.space =
+					-mddev->bitmap_info.offset;
+		}
+
+		if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
+			mddev->reshape_position = le64_to_cpu(sb->reshape_position);
+			mddev->delta_disks = le32_to_cpu(sb->delta_disks);
+			mddev->new_level = le32_to_cpu(sb->new_level);
+			mddev->new_layout = le32_to_cpu(sb->new_layout);
+			mddev->new_chunk_sectors = le32_to_cpu(sb->new_chunk);
+			if (mddev->delta_disks < 0 ||
+			    (mddev->delta_disks == 0 &&
+			     (le32_to_cpu(sb->feature_map)
+			      & MD_FEATURE_RESHAPE_BACKWARDS)))
+				mddev->reshape_backwards = 1;
+		} else {
+			mddev->reshape_position = MaxSector;
+			mddev->delta_disks = 0;
+			mddev->new_level = mddev->level;
+			mddev->new_layout = mddev->layout;
+			mddev->new_chunk_sectors = mddev->chunk_sectors;
+		}
+
+	} else if (mddev->pers == NULL) {
+		/* Insist of good event counter while assembling, except for
+		 * spares (which don't need an event count) */
+		++ev1;
+		if (rdev->desc_nr >= 0 &&
+		    rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
+		    le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < 0xfffe)
+			if (ev1 < mddev->events)
+				return -EINVAL;
+	} else if (mddev->bitmap) {
+		/* If adding to array with a bitmap, then we can accept an
+		 * older device, but not too old.
+		 */
+		if (ev1 < mddev->bitmap->events_cleared)
+			return 0;
+		if (ev1 < mddev->events)
+			set_bit(Bitmap_sync, &rdev->flags);
+	} else {
+		if (ev1 < mddev->events)
+			/* just a hot-add of a new device, leave raid_disk at -1 */
+			return 0;
+	}
+	if (mddev->level != LEVEL_MULTIPATH) {
+		int role;
+		if (rdev->desc_nr < 0 ||
+		    rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
+			role = 0xffff;
+			rdev->desc_nr = -1;
+		} else
+			role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
+		switch(role) {
+		case 0xffff: /* spare */
+			break;
+		case 0xfffe: /* faulty */
+			set_bit(Faulty, &rdev->flags);
+			break;
+		default:
+			rdev->saved_raid_disk = role;
+			if ((le32_to_cpu(sb->feature_map) &
+			     MD_FEATURE_RECOVERY_OFFSET)) {
+				rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
+				if (!(le32_to_cpu(sb->feature_map) &
+				      MD_FEATURE_RECOVERY_BITMAP))
+					rdev->saved_raid_disk = -1;
+			} else
+				set_bit(In_sync, &rdev->flags);
+			rdev->raid_disk = role;
+			break;
+		}
+		if (sb->devflags & WriteMostly1)
+			set_bit(WriteMostly, &rdev->flags);
+		if (le32_to_cpu(sb->feature_map) & MD_FEATURE_REPLACEMENT)
+			set_bit(Replacement, &rdev->flags);
+	} else /* MULTIPATH are always insync */
+		set_bit(In_sync, &rdev->flags);
+
+	return 0;
+}
+
+static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
+{
+	struct mdp_superblock_1 *sb;
+	struct md_rdev *rdev2;
+	int max_dev, i;
+	/* make rdev->sb match mddev and rdev data. */
+
+	sb = page_address(rdev->sb_page);
+
+	sb->feature_map = 0;
+	sb->pad0 = 0;
+	sb->recovery_offset = cpu_to_le64(0);
+	memset(sb->pad3, 0, sizeof(sb->pad3));
+
+	sb->utime = cpu_to_le64((__u64)mddev->utime);
+	sb->events = cpu_to_le64(mddev->events);
+	if (mddev->in_sync)
+		sb->resync_offset = cpu_to_le64(mddev->recovery_cp);
+	else
+		sb->resync_offset = cpu_to_le64(0);
+
+	sb->cnt_corrected_read = cpu_to_le32(atomic_read(&rdev->corrected_errors));
+
+	sb->raid_disks = cpu_to_le32(mddev->raid_disks);
+	sb->size = cpu_to_le64(mddev->dev_sectors);
+	sb->chunksize = cpu_to_le32(mddev->chunk_sectors);
+	sb->level = cpu_to_le32(mddev->level);
+	sb->layout = cpu_to_le32(mddev->layout);
+
+	if (test_bit(WriteMostly, &rdev->flags))
+		sb->devflags |= WriteMostly1;
+	else
+		sb->devflags &= ~WriteMostly1;
+	sb->data_offset = cpu_to_le64(rdev->data_offset);
+	sb->data_size = cpu_to_le64(rdev->sectors);
+
+	if (mddev->bitmap && mddev->bitmap_info.file == NULL) {
+		sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_info.offset);
+		sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
+	}
+
+	if (rdev->raid_disk >= 0 &&
+	    !test_bit(In_sync, &rdev->flags)) {
+		sb->feature_map |=
+			cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
+		sb->recovery_offset =
+			cpu_to_le64(rdev->recovery_offset);
+		if (rdev->saved_raid_disk >= 0 && mddev->bitmap)
+			sb->feature_map |=
+				cpu_to_le32(MD_FEATURE_RECOVERY_BITMAP);
+	}
+	if (test_bit(Replacement, &rdev->flags))
+		sb->feature_map |=
+			cpu_to_le32(MD_FEATURE_REPLACEMENT);
+
+	if (mddev->reshape_position != MaxSector) {
+		sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
+		sb->reshape_position = cpu_to_le64(mddev->reshape_position);
+		sb->new_layout = cpu_to_le32(mddev->new_layout);
+		sb->delta_disks = cpu_to_le32(mddev->delta_disks);
+		sb->new_level = cpu_to_le32(mddev->new_level);
+		sb->new_chunk = cpu_to_le32(mddev->new_chunk_sectors);
+		if (mddev->delta_disks == 0 &&
+		    mddev->reshape_backwards)
+			sb->feature_map
+				|= cpu_to_le32(MD_FEATURE_RESHAPE_BACKWARDS);
+		if (rdev->new_data_offset != rdev->data_offset) {
+			sb->feature_map
+				|= cpu_to_le32(MD_FEATURE_NEW_OFFSET);
+			sb->new_offset = cpu_to_le32((__u32)(rdev->new_data_offset
+							     - rdev->data_offset));
+		}
+	}
+
+	if (rdev->badblocks.count == 0)
+		/* Nothing to do for bad blocks*/ ;
+	else if (sb->bblog_offset == 0)
+		/* Cannot record bad blocks on this device */
+		md_error(mddev, rdev);
+	else {
+		struct badblocks *bb = &rdev->badblocks;
+		u64 *bbp = (u64 *)page_address(rdev->bb_page);
+		u64 *p = bb->page;
+		sb->feature_map |= cpu_to_le32(MD_FEATURE_BAD_BLOCKS);
+		if (bb->changed) {
+			unsigned seq;
+
+retry:
+			seq = read_seqbegin(&bb->lock);
+
+			memset(bbp, 0xff, PAGE_SIZE);
+
+			for (i = 0 ; i < bb->count ; i++) {
+				u64 internal_bb = p[i];
+				u64 store_bb = ((BB_OFFSET(internal_bb) << 10)
+						| BB_LEN(internal_bb));
+				bbp[i] = cpu_to_le64(store_bb);
+			}
+			bb->changed = 0;
+			if (read_seqretry(&bb->lock, seq))
+				goto retry;
+
+			bb->sector = (rdev->sb_start +
+				      (int)le32_to_cpu(sb->bblog_offset));
+			bb->size = le16_to_cpu(sb->bblog_size);
+		}
+	}
+
+	max_dev = 0;
+	rdev_for_each(rdev2, mddev)
+		if (rdev2->desc_nr+1 > max_dev)
+			max_dev = rdev2->desc_nr+1;
+
+	if (max_dev > le32_to_cpu(sb->max_dev)) {
+		int bmask;
+		sb->max_dev = cpu_to_le32(max_dev);
+		rdev->sb_size = max_dev * 2 + 256;
+		bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
+		if (rdev->sb_size & bmask)
+			rdev->sb_size = (rdev->sb_size | bmask) + 1;
+	} else
+		max_dev = le32_to_cpu(sb->max_dev);
+
+	for (i=0; i<max_dev;i++)
+		sb->dev_roles[i] = cpu_to_le16(0xfffe);
+
+	rdev_for_each(rdev2, mddev) {
+		i = rdev2->desc_nr;
+		if (test_bit(Faulty, &rdev2->flags))
+			sb->dev_roles[i] = cpu_to_le16(0xfffe);
+		else if (test_bit(In_sync, &rdev2->flags))
+			sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
+		else if (rdev2->raid_disk >= 0)
+			sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
+		else
+			sb->dev_roles[i] = cpu_to_le16(0xffff);
+	}
+
+	sb->sb_csum = calc_sb_1_csum(sb);
+}
+
+static unsigned long long
+super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
+{
+	struct mdp_superblock_1 *sb;
+	sector_t max_sectors;
+	if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
+		return 0; /* component must fit device */
+	if (rdev->data_offset != rdev->new_data_offset)
+		return 0; /* too confusing */
+	if (rdev->sb_start < rdev->data_offset) {
+		/* minor versions 1 and 2; superblock before data */
+		max_sectors = i_size_read(rdev->bdev->bd_inode) >> 9;
+		max_sectors -= rdev->data_offset;
+		if (!num_sectors || num_sectors > max_sectors)
+			num_sectors = max_sectors;
+	} else if (rdev->mddev->bitmap_info.offset) {
+		/* minor version 0 with bitmap we can't move */
+		return 0;
+	} else {
+		/* minor version 0; superblock after data */
+		sector_t sb_start;
+		sb_start = (i_size_read(rdev->bdev->bd_inode) >> 9) - 8*2;
+		sb_start &= ~(sector_t)(4*2 - 1);
+		max_sectors = rdev->sectors + sb_start - rdev->sb_start;
+		if (!num_sectors || num_sectors > max_sectors)
+			num_sectors = max_sectors;
+		rdev->sb_start = sb_start;
+	}
+	sb = page_address(rdev->sb_page);
+	sb->data_size = cpu_to_le64(num_sectors);
+	sb->super_offset = rdev->sb_start;
+	sb->sb_csum = calc_sb_1_csum(sb);
+	md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
+		       rdev->sb_page);
+	md_super_wait(rdev->mddev);
+	return num_sectors;
+
+}
+
+static int
+super_1_allow_new_offset(struct md_rdev *rdev,
+			 unsigned long long new_offset)
+{
+	/* All necessary checks on new >= old have been done */
+	struct bitmap *bitmap;
+	if (new_offset >= rdev->data_offset)
+		return 1;
+
+	/* with 1.0 metadata, there is no metadata to tread on
+	 * so we can always move back */
+	if (rdev->mddev->minor_version == 0)
+		return 1;
+
+	/* otherwise we must be sure not to step on
+	 * any metadata, so stay:
+	 * 36K beyond start of superblock
+	 * beyond end of badblocks
+	 * beyond write-intent bitmap
+	 */
+	if (rdev->sb_start + (32+4)*2 > new_offset)
+		return 0;
+	bitmap = rdev->mddev->bitmap;
+	if (bitmap && !rdev->mddev->bitmap_info.file &&
+	    rdev->sb_start + rdev->mddev->bitmap_info.offset +
+	    bitmap->storage.file_pages * (PAGE_SIZE>>9) > new_offset)
+		return 0;
+	if (rdev->badblocks.sector + rdev->badblocks.size > new_offset)
+		return 0;
+
+	return 1;
+}
+
+static struct super_type super_types[] = {
+	[0] = {
+		.name	= "0.90.0",
+		.owner	= THIS_MODULE,
+		.load_super	    = super_90_load,
+		.validate_super	    = super_90_validate,
+		.sync_super	    = super_90_sync,
+		.rdev_size_change   = super_90_rdev_size_change,
+		.allow_new_offset   = super_90_allow_new_offset,
+	},
+	[1] = {
+		.name	= "md-1",
+		.owner	= THIS_MODULE,
+		.load_super	    = super_1_load,
+		.validate_super	    = super_1_validate,
+		.sync_super	    = super_1_sync,
+		.rdev_size_change   = super_1_rdev_size_change,
+		.allow_new_offset   = super_1_allow_new_offset,
+	},
+};
+
+static void sync_super(struct mddev *mddev, struct md_rdev *rdev)
+{
+	if (mddev->sync_super) {
+		mddev->sync_super(mddev, rdev);
+		return;
+	}
+
+	BUG_ON(mddev->major_version >= ARRAY_SIZE(super_types));
+
+	super_types[mddev->major_version].sync_super(mddev, rdev);
+}
+
+static int match_mddev_units(struct mddev *mddev1, struct mddev *mddev2)
+{
+	struct md_rdev *rdev, *rdev2;
+
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev1)
+		rdev_for_each_rcu(rdev2, mddev2)
+			if (rdev->bdev->bd_contains ==
+			    rdev2->bdev->bd_contains) {
+				rcu_read_unlock();
+				return 1;
+			}
+	rcu_read_unlock();
+	return 0;
+}
+
+static LIST_HEAD(pending_raid_disks);
+
+/*
+ * Try to register data integrity profile for an mddev
+ *
+ * This is called when an array is started and after a disk has been kicked
+ * from the array. It only succeeds if all working and active component devices
+ * are integrity capable with matching profiles.
+ */
+int md_integrity_register(struct mddev *mddev)
+{
+	struct md_rdev *rdev, *reference = NULL;
+
+	if (list_empty(&mddev->disks))
+		return 0; /* nothing to do */
+	if (!mddev->gendisk || blk_get_integrity(mddev->gendisk))
+		return 0; /* shouldn't register, or already is */
+	rdev_for_each(rdev, mddev) {
+		/* skip spares and non-functional disks */
+		if (test_bit(Faulty, &rdev->flags))
+			continue;
+		if (rdev->raid_disk < 0)
+			continue;
+		if (!reference) {
+			/* Use the first rdev as the reference */
+			reference = rdev;
+			continue;
+		}
+		/* does this rdev's profile match the reference profile? */
+		if (blk_integrity_compare(reference->bdev->bd_disk,
+				rdev->bdev->bd_disk) < 0)
+			return -EINVAL;
+	}
+	if (!reference || !bdev_get_integrity(reference->bdev))
+		return 0;
+	/*
+	 * All component devices are integrity capable and have matching
+	 * profiles, register the common profile for the md device.
+	 */
+	if (blk_integrity_register(mddev->gendisk,
+			bdev_get_integrity(reference->bdev)) != 0) {
+		printk(KERN_ERR "md: failed to register integrity for %s\n",
+			mdname(mddev));
+		return -EINVAL;
+	}
+	printk(KERN_NOTICE "md: data integrity enabled on %s\n", mdname(mddev));
+	if (bioset_integrity_create(mddev->bio_set, BIO_POOL_SIZE)) {
+		printk(KERN_ERR "md: failed to create integrity pool for %s\n",
+		       mdname(mddev));
+		return -EINVAL;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(md_integrity_register);
+
+/* Disable data integrity if non-capable/non-matching disk is being added */
+void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev)
+{
+	struct blk_integrity *bi_rdev;
+	struct blk_integrity *bi_mddev;
+
+	if (!mddev->gendisk)
+		return;
+
+	bi_rdev = bdev_get_integrity(rdev->bdev);
+	bi_mddev = blk_get_integrity(mddev->gendisk);
+
+	if (!bi_mddev) /* nothing to do */
+		return;
+	if (rdev->raid_disk < 0) /* skip spares */
+		return;
+	if (bi_rdev && blk_integrity_compare(mddev->gendisk,
+					     rdev->bdev->bd_disk) >= 0)
+		return;
+	printk(KERN_NOTICE "disabling data integrity on %s\n", mdname(mddev));
+	blk_integrity_unregister(mddev->gendisk);
+}
+EXPORT_SYMBOL(md_integrity_add_rdev);
+
+static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
+{
+	char b[BDEVNAME_SIZE];
+	struct kobject *ko;
+	char *s;
+	int err;
+
+	/* prevent duplicates */
+	if (find_rdev(mddev, rdev->bdev->bd_dev))
+		return -EEXIST;
+
+	/* make sure rdev->sectors exceeds mddev->dev_sectors */
+	if (rdev->sectors && (mddev->dev_sectors == 0 ||
+			rdev->sectors < mddev->dev_sectors)) {
+		if (mddev->pers) {
+			/* Cannot change size, so fail
+			 * If mddev->level <= 0, then we don't care
+			 * about aligning sizes (e.g. linear)
+			 */
+			if (mddev->level > 0)
+				return -ENOSPC;
+		} else
+			mddev->dev_sectors = rdev->sectors;
+	}
+
+	/* Verify rdev->desc_nr is unique.
+	 * If it is -1, assign a free number, else
+	 * check number is not in use
+	 */
+	rcu_read_lock();
+	if (rdev->desc_nr < 0) {
+		int choice = 0;
+		if (mddev->pers)
+			choice = mddev->raid_disks;
+		while (md_find_rdev_nr_rcu(mddev, choice))
+			choice++;
+		rdev->desc_nr = choice;
+	} else {
+		if (md_find_rdev_nr_rcu(mddev, rdev->desc_nr)) {
+			rcu_read_unlock();
+			return -EBUSY;
+		}
+	}
+	rcu_read_unlock();
+	if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
+		printk(KERN_WARNING "md: %s: array is limited to %d devices\n",
+		       mdname(mddev), mddev->max_disks);
+		return -EBUSY;
+	}
+	bdevname(rdev->bdev,b);
+	while ( (s=strchr(b, '/')) != NULL)
+		*s = '!';
+
+	rdev->mddev = mddev;
+	printk(KERN_INFO "md: bind<%s>\n", b);
+
+	if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
+		goto fail;
+
+	ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
+	if (sysfs_create_link(&rdev->kobj, ko, "block"))
+		/* failure here is OK */;
+	rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
+
+	list_add_rcu(&rdev->same_set, &mddev->disks);
+	bd_link_disk_holder(rdev->bdev, mddev->gendisk);
+
+	/* May as well allow recovery to be retried once */
+	mddev->recovery_disabled++;
+
+	return 0;
+
+ fail:
+	printk(KERN_WARNING "md: failed to register dev-%s for %s\n",
+	       b, mdname(mddev));
+	return err;
+}
+
+static void md_delayed_delete(struct work_struct *ws)
+{
+	struct md_rdev *rdev = container_of(ws, struct md_rdev, del_work);
+	kobject_del(&rdev->kobj);
+	kobject_put(&rdev->kobj);
+}
+
+static void unbind_rdev_from_array(struct md_rdev *rdev)
+{
+	char b[BDEVNAME_SIZE];
+
+	bd_unlink_disk_holder(rdev->bdev, rdev->mddev->gendisk);
+	list_del_rcu(&rdev->same_set);
+	printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
+	rdev->mddev = NULL;
+	sysfs_remove_link(&rdev->kobj, "block");
+	sysfs_put(rdev->sysfs_state);
+	rdev->sysfs_state = NULL;
+	rdev->badblocks.count = 0;
+	/* We need to delay this, otherwise we can deadlock when
+	 * writing to 'remove' to "dev/state".  We also need
+	 * to delay it due to rcu usage.
+	 */
+	synchronize_rcu();
+	INIT_WORK(&rdev->del_work, md_delayed_delete);
+	kobject_get(&rdev->kobj);
+	queue_work(md_misc_wq, &rdev->del_work);
+}
+
+/*
+ * prevent the device from being mounted, repartitioned or
+ * otherwise reused by a RAID array (or any other kernel
+ * subsystem), by bd_claiming the device.
+ */
+static int lock_rdev(struct md_rdev *rdev, dev_t dev, int shared)
+{
+	int err = 0;
+	struct block_device *bdev;
+	char b[BDEVNAME_SIZE];
+
+	bdev = blkdev_get_by_dev(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
+				 shared ? (struct md_rdev *)lock_rdev : rdev);
+	if (IS_ERR(bdev)) {
+		printk(KERN_ERR "md: could not open %s.\n",
+			__bdevname(dev, b));
+		return PTR_ERR(bdev);
+	}
+	rdev->bdev = bdev;
+	return err;
+}
+
+static void unlock_rdev(struct md_rdev *rdev)
+{
+	struct block_device *bdev = rdev->bdev;
+	rdev->bdev = NULL;
+	blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
+}
+
+void md_autodetect_dev(dev_t dev);
+
+static void export_rdev(struct md_rdev *rdev)
+{
+	char b[BDEVNAME_SIZE];
+
+	printk(KERN_INFO "md: export_rdev(%s)\n",
+		bdevname(rdev->bdev,b));
+	md_rdev_clear(rdev);
+#ifndef MODULE
+	if (test_bit(AutoDetected, &rdev->flags))
+		md_autodetect_dev(rdev->bdev->bd_dev);
+#endif
+	unlock_rdev(rdev);
+	kobject_put(&rdev->kobj);
+}
+
+void md_kick_rdev_from_array(struct md_rdev *rdev)
+{
+	unbind_rdev_from_array(rdev);
+	export_rdev(rdev);
+}
+EXPORT_SYMBOL_GPL(md_kick_rdev_from_array);
+
+static void export_array(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+
+	while (!list_empty(&mddev->disks)) {
+		rdev = list_first_entry(&mddev->disks, struct md_rdev,
+					same_set);
+		md_kick_rdev_from_array(rdev);
+	}
+	mddev->raid_disks = 0;
+	mddev->major_version = 0;
+}
+
+static void sync_sbs(struct mddev *mddev, int nospares)
+{
+	/* Update each superblock (in-memory image), but
+	 * if we are allowed to, skip spares which already
+	 * have the right event counter, or have one earlier
+	 * (which would mean they aren't being marked as dirty
+	 * with the rest of the array)
+	 */
+	struct md_rdev *rdev;
+	rdev_for_each(rdev, mddev) {
+		if (rdev->sb_events == mddev->events ||
+		    (nospares &&
+		     rdev->raid_disk < 0 &&
+		     rdev->sb_events+1 == mddev->events)) {
+			/* Don't update this superblock */
+			rdev->sb_loaded = 2;
+		} else {
+			sync_super(mddev, rdev);
+			rdev->sb_loaded = 1;
+		}
+	}
+}
+
+void md_update_sb(struct mddev *mddev, int force_change)
+{
+	struct md_rdev *rdev;
+	int sync_req;
+	int nospares = 0;
+	int any_badblocks_changed = 0;
+
+	if (mddev->ro) {
+		if (force_change)
+			set_bit(MD_CHANGE_DEVS, &mddev->flags);
+		return;
+	}
+repeat:
+	/* First make sure individual recovery_offsets are correct */
+	rdev_for_each(rdev, mddev) {
+		if (rdev->raid_disk >= 0 &&
+		    mddev->delta_disks >= 0 &&
+		    !test_bit(In_sync, &rdev->flags) &&
+		    mddev->curr_resync_completed > rdev->recovery_offset)
+				rdev->recovery_offset = mddev->curr_resync_completed;
+
+	}
+	if (!mddev->persistent) {
+		clear_bit(MD_CHANGE_CLEAN, &mddev->flags);
+		clear_bit(MD_CHANGE_DEVS, &mddev->flags);
+		if (!mddev->external) {
+			clear_bit(MD_CHANGE_PENDING, &mddev->flags);
+			rdev_for_each(rdev, mddev) {
+				if (rdev->badblocks.changed) {
+					rdev->badblocks.changed = 0;
+					md_ack_all_badblocks(&rdev->badblocks);
+					md_error(mddev, rdev);
+				}
+				clear_bit(Blocked, &rdev->flags);
+				clear_bit(BlockedBadBlocks, &rdev->flags);
+				wake_up(&rdev->blocked_wait);
+			}
+		}
+		wake_up(&mddev->sb_wait);
+		return;
+	}
+
+	spin_lock(&mddev->lock);
+
+	mddev->utime = get_seconds();
+
+	if (test_and_clear_bit(MD_CHANGE_DEVS, &mddev->flags))
+		force_change = 1;
+	if (test_and_clear_bit(MD_CHANGE_CLEAN, &mddev->flags))
+		/* just a clean<-> dirty transition, possibly leave spares alone,
+		 * though if events isn't the right even/odd, we will have to do
+		 * spares after all
+		 */
+		nospares = 1;
+	if (force_change)
+		nospares = 0;
+	if (mddev->degraded)
+		/* If the array is degraded, then skipping spares is both
+		 * dangerous and fairly pointless.
+		 * Dangerous because a device that was removed from the array
+		 * might have a event_count that still looks up-to-date,
+		 * so it can be re-added without a resync.
+		 * Pointless because if there are any spares to skip,
+		 * then a recovery will happen and soon that array won't
+		 * be degraded any more and the spare can go back to sleep then.
+		 */
+		nospares = 0;
+
+	sync_req = mddev->in_sync;
+
+	/* If this is just a dirty<->clean transition, and the array is clean
+	 * and 'events' is odd, we can roll back to the previous clean state */
+	if (nospares
+	    && (mddev->in_sync && mddev->recovery_cp == MaxSector)
+	    && mddev->can_decrease_events
+	    && mddev->events != 1) {
+		mddev->events--;
+		mddev->can_decrease_events = 0;
+	} else {
+		/* otherwise we have to go forward and ... */
+		mddev->events ++;
+		mddev->can_decrease_events = nospares;
+	}
+
+	/*
+	 * This 64-bit counter should never wrap.
+	 * Either we are in around ~1 trillion A.C., assuming
+	 * 1 reboot per second, or we have a bug...
+	 */
+	WARN_ON(mddev->events == 0);
+
+	rdev_for_each(rdev, mddev) {
+		if (rdev->badblocks.changed)
+			any_badblocks_changed++;
+		if (test_bit(Faulty, &rdev->flags))
+			set_bit(FaultRecorded, &rdev->flags);
+	}
+
+	sync_sbs(mddev, nospares);
+	spin_unlock(&mddev->lock);
+
+	pr_debug("md: updating %s RAID superblock on device (in sync %d)\n",
+		 mdname(mddev), mddev->in_sync);
+
+	bitmap_update_sb(mddev->bitmap);
+	rdev_for_each(rdev, mddev) {
+		char b[BDEVNAME_SIZE];
+
+		if (rdev->sb_loaded != 1)
+			continue; /* no noise on spare devices */
+
+		if (!test_bit(Faulty, &rdev->flags)) {
+			md_super_write(mddev,rdev,
+				       rdev->sb_start, rdev->sb_size,
+				       rdev->sb_page);
+			pr_debug("md: (write) %s's sb offset: %llu\n",
+				 bdevname(rdev->bdev, b),
+				 (unsigned long long)rdev->sb_start);
+			rdev->sb_events = mddev->events;
+			if (rdev->badblocks.size) {
+				md_super_write(mddev, rdev,
+					       rdev->badblocks.sector,
+					       rdev->badblocks.size << 9,
+					       rdev->bb_page);
+				rdev->badblocks.size = 0;
+			}
+
+		} else
+			pr_debug("md: %s (skipping faulty)\n",
+				 bdevname(rdev->bdev, b));
+
+		if (mddev->level == LEVEL_MULTIPATH)
+			/* only need to write one superblock... */
+			break;
+	}
+	md_super_wait(mddev);
+	/* if there was a failure, MD_CHANGE_DEVS was set, and we re-write super */
+
+	spin_lock(&mddev->lock);
+	if (mddev->in_sync != sync_req ||
+	    test_bit(MD_CHANGE_DEVS, &mddev->flags)) {
+		/* have to write it out again */
+		spin_unlock(&mddev->lock);
+		goto repeat;
+	}
+	clear_bit(MD_CHANGE_PENDING, &mddev->flags);
+	spin_unlock(&mddev->lock);
+	wake_up(&mddev->sb_wait);
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+
+	rdev_for_each(rdev, mddev) {
+		if (test_and_clear_bit(FaultRecorded, &rdev->flags))
+			clear_bit(Blocked, &rdev->flags);
+
+		if (any_badblocks_changed)
+			md_ack_all_badblocks(&rdev->badblocks);
+		clear_bit(BlockedBadBlocks, &rdev->flags);
+		wake_up(&rdev->blocked_wait);
+	}
+}
+EXPORT_SYMBOL(md_update_sb);
+
+static int add_bound_rdev(struct md_rdev *rdev)
+{
+	struct mddev *mddev = rdev->mddev;
+	int err = 0;
+
+	if (!mddev->pers->hot_remove_disk) {
+		/* If there is hot_add_disk but no hot_remove_disk
+		 * then added disks for geometry changes,
+		 * and should be added immediately.
+		 */
+		super_types[mddev->major_version].
+			validate_super(mddev, rdev);
+		err = mddev->pers->hot_add_disk(mddev, rdev);
+		if (err) {
+			unbind_rdev_from_array(rdev);
+			export_rdev(rdev);
+			return err;
+		}
+	}
+	sysfs_notify_dirent_safe(rdev->sysfs_state);
+
+	set_bit(MD_CHANGE_DEVS, &mddev->flags);
+	if (mddev->degraded)
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_new_event(mddev);
+	md_wakeup_thread(mddev->thread);
+	return 0;
+}
+
+/* words written to sysfs files may, or may not, be \n terminated.
+ * We want to accept with case. For this we use cmd_match.
+ */
+static int cmd_match(const char *cmd, const char *str)
+{
+	/* See if cmd, written into a sysfs file, matches
+	 * str.  They must either be the same, or cmd can
+	 * have a trailing newline
+	 */
+	while (*cmd && *str && *cmd == *str) {
+		cmd++;
+		str++;
+	}
+	if (*cmd == '\n')
+		cmd++;
+	if (*str || *cmd)
+		return 0;
+	return 1;
+}
+
+struct rdev_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct md_rdev *, char *);
+	ssize_t (*store)(struct md_rdev *, const char *, size_t);
+};
+
+static ssize_t
+state_show(struct md_rdev *rdev, char *page)
+{
+	char *sep = "";
+	size_t len = 0;
+	unsigned long flags = ACCESS_ONCE(rdev->flags);
+
+	if (test_bit(Faulty, &flags) ||
+	    rdev->badblocks.unacked_exist) {
+		len+= sprintf(page+len, "%sfaulty",sep);
+		sep = ",";
+	}
+	if (test_bit(In_sync, &flags)) {
+		len += sprintf(page+len, "%sin_sync",sep);
+		sep = ",";
+	}
+	if (test_bit(WriteMostly, &flags)) {
+		len += sprintf(page+len, "%swrite_mostly",sep);
+		sep = ",";
+	}
+	if (test_bit(Blocked, &flags) ||
+	    (rdev->badblocks.unacked_exist
+	     && !test_bit(Faulty, &flags))) {
+		len += sprintf(page+len, "%sblocked", sep);
+		sep = ",";
+	}
+	if (!test_bit(Faulty, &flags) &&
+	    !test_bit(In_sync, &flags)) {
+		len += sprintf(page+len, "%sspare", sep);
+		sep = ",";
+	}
+	if (test_bit(WriteErrorSeen, &flags)) {
+		len += sprintf(page+len, "%swrite_error", sep);
+		sep = ",";
+	}
+	if (test_bit(WantReplacement, &flags)) {
+		len += sprintf(page+len, "%swant_replacement", sep);
+		sep = ",";
+	}
+	if (test_bit(Replacement, &flags)) {
+		len += sprintf(page+len, "%sreplacement", sep);
+		sep = ",";
+	}
+
+	return len+sprintf(page+len, "\n");
+}
+
+static ssize_t
+state_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	/* can write
+	 *  faulty  - simulates an error
+	 *  remove  - disconnects the device
+	 *  writemostly - sets write_mostly
+	 *  -writemostly - clears write_mostly
+	 *  blocked - sets the Blocked flags
+	 *  -blocked - clears the Blocked and possibly simulates an error
+	 *  insync - sets Insync providing device isn't active
+	 *  -insync - clear Insync for a device with a slot assigned,
+	 *            so that it gets rebuilt based on bitmap
+	 *  write_error - sets WriteErrorSeen
+	 *  -write_error - clears WriteErrorSeen
+	 */
+	int err = -EINVAL;
+	if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
+		md_error(rdev->mddev, rdev);
+		if (test_bit(Faulty, &rdev->flags))
+			err = 0;
+		else
+			err = -EBUSY;
+	} else if (cmd_match(buf, "remove")) {
+		if (rdev->raid_disk >= 0)
+			err = -EBUSY;
+		else {
+			struct mddev *mddev = rdev->mddev;
+			if (mddev_is_clustered(mddev))
+				md_cluster_ops->remove_disk(mddev, rdev);
+			md_kick_rdev_from_array(rdev);
+			if (mddev_is_clustered(mddev))
+				md_cluster_ops->metadata_update_start(mddev);
+			if (mddev->pers)
+				md_update_sb(mddev, 1);
+			md_new_event(mddev);
+			if (mddev_is_clustered(mddev))
+				md_cluster_ops->metadata_update_finish(mddev);
+			err = 0;
+		}
+	} else if (cmd_match(buf, "writemostly")) {
+		set_bit(WriteMostly, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "-writemostly")) {
+		clear_bit(WriteMostly, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "blocked")) {
+		set_bit(Blocked, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "-blocked")) {
+		if (!test_bit(Faulty, &rdev->flags) &&
+		    rdev->badblocks.unacked_exist) {
+			/* metadata handler doesn't understand badblocks,
+			 * so we need to fail the device
+			 */
+			md_error(rdev->mddev, rdev);
+		}
+		clear_bit(Blocked, &rdev->flags);
+		clear_bit(BlockedBadBlocks, &rdev->flags);
+		wake_up(&rdev->blocked_wait);
+		set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
+		md_wakeup_thread(rdev->mddev->thread);
+
+		err = 0;
+	} else if (cmd_match(buf, "insync") && rdev->raid_disk == -1) {
+		set_bit(In_sync, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "-insync") && rdev->raid_disk >= 0) {
+		if (rdev->mddev->pers == NULL) {
+			clear_bit(In_sync, &rdev->flags);
+			rdev->saved_raid_disk = rdev->raid_disk;
+			rdev->raid_disk = -1;
+			err = 0;
+		}
+	} else if (cmd_match(buf, "write_error")) {
+		set_bit(WriteErrorSeen, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "-write_error")) {
+		clear_bit(WriteErrorSeen, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "want_replacement")) {
+		/* Any non-spare device that is not a replacement can
+		 * become want_replacement at any time, but we then need to
+		 * check if recovery is needed.
+		 */
+		if (rdev->raid_disk >= 0 &&
+		    !test_bit(Replacement, &rdev->flags))
+			set_bit(WantReplacement, &rdev->flags);
+		set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
+		md_wakeup_thread(rdev->mddev->thread);
+		err = 0;
+	} else if (cmd_match(buf, "-want_replacement")) {
+		/* Clearing 'want_replacement' is always allowed.
+		 * Once replacements starts it is too late though.
+		 */
+		err = 0;
+		clear_bit(WantReplacement, &rdev->flags);
+	} else if (cmd_match(buf, "replacement")) {
+		/* Can only set a device as a replacement when array has not
+		 * yet been started.  Once running, replacement is automatic
+		 * from spares, or by assigning 'slot'.
+		 */
+		if (rdev->mddev->pers)
+			err = -EBUSY;
+		else {
+			set_bit(Replacement, &rdev->flags);
+			err = 0;
+		}
+	} else if (cmd_match(buf, "-replacement")) {
+		/* Similarly, can only clear Replacement before start */
+		if (rdev->mddev->pers)
+			err = -EBUSY;
+		else {
+			clear_bit(Replacement, &rdev->flags);
+			err = 0;
+		}
+	} else if (cmd_match(buf, "re-add")) {
+		if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1)) {
+			/* clear_bit is performed _after_ all the devices
+			 * have their local Faulty bit cleared. If any writes
+			 * happen in the meantime in the local node, they
+			 * will land in the local bitmap, which will be synced
+			 * by this node eventually
+			 */
+			if (!mddev_is_clustered(rdev->mddev) ||
+			    (err = md_cluster_ops->gather_bitmaps(rdev)) == 0) {
+				clear_bit(Faulty, &rdev->flags);
+				err = add_bound_rdev(rdev);
+			}
+		} else
+			err = -EBUSY;
+	}
+	if (!err)
+		sysfs_notify_dirent_safe(rdev->sysfs_state);
+	return err ? err : len;
+}
+static struct rdev_sysfs_entry rdev_state =
+__ATTR_PREALLOC(state, S_IRUGO|S_IWUSR, state_show, state_store);
+
+static ssize_t
+errors_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
+}
+
+static ssize_t
+errors_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	char *e;
+	unsigned long n = simple_strtoul(buf, &e, 10);
+	if (*buf && (*e == 0 || *e == '\n')) {
+		atomic_set(&rdev->corrected_errors, n);
+		return len;
+	}
+	return -EINVAL;
+}
+static struct rdev_sysfs_entry rdev_errors =
+__ATTR(errors, S_IRUGO|S_IWUSR, errors_show, errors_store);
+
+static ssize_t
+slot_show(struct md_rdev *rdev, char *page)
+{
+	if (rdev->raid_disk < 0)
+		return sprintf(page, "none\n");
+	else
+		return sprintf(page, "%d\n", rdev->raid_disk);
+}
+
+static ssize_t
+slot_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	char *e;
+	int err;
+	int slot = simple_strtoul(buf, &e, 10);
+	if (strncmp(buf, "none", 4)==0)
+		slot = -1;
+	else if (e==buf || (*e && *e!= '\n'))
+		return -EINVAL;
+	if (rdev->mddev->pers && slot == -1) {
+		/* Setting 'slot' on an active array requires also
+		 * updating the 'rd%d' link, and communicating
+		 * with the personality with ->hot_*_disk.
+		 * For now we only support removing
+		 * failed/spare devices.  This normally happens automatically,
+		 * but not when the metadata is externally managed.
+		 */
+		if (rdev->raid_disk == -1)
+			return -EEXIST;
+		/* personality does all needed checks */
+		if (rdev->mddev->pers->hot_remove_disk == NULL)
+			return -EINVAL;
+		clear_bit(Blocked, &rdev->flags);
+		remove_and_add_spares(rdev->mddev, rdev);
+		if (rdev->raid_disk >= 0)
+			return -EBUSY;
+		set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
+		md_wakeup_thread(rdev->mddev->thread);
+	} else if (rdev->mddev->pers) {
+		/* Activating a spare .. or possibly reactivating
+		 * if we ever get bitmaps working here.
+		 */
+
+		if (rdev->raid_disk != -1)
+			return -EBUSY;
+
+		if (test_bit(MD_RECOVERY_RUNNING, &rdev->mddev->recovery))
+			return -EBUSY;
+
+		if (rdev->mddev->pers->hot_add_disk == NULL)
+			return -EINVAL;
+
+		if (slot >= rdev->mddev->raid_disks &&
+		    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
+			return -ENOSPC;
+
+		rdev->raid_disk = slot;
+		if (test_bit(In_sync, &rdev->flags))
+			rdev->saved_raid_disk = slot;
+		else
+			rdev->saved_raid_disk = -1;
+		clear_bit(In_sync, &rdev->flags);
+		clear_bit(Bitmap_sync, &rdev->flags);
+		err = rdev->mddev->pers->
+			hot_add_disk(rdev->mddev, rdev);
+		if (err) {
+			rdev->raid_disk = -1;
+			return err;
+		} else
+			sysfs_notify_dirent_safe(rdev->sysfs_state);
+		if (sysfs_link_rdev(rdev->mddev, rdev))
+			/* failure here is OK */;
+		/* don't wakeup anyone, leave that to userspace. */
+	} else {
+		if (slot >= rdev->mddev->raid_disks &&
+		    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
+			return -ENOSPC;
+		rdev->raid_disk = slot;
+		/* assume it is working */
+		clear_bit(Faulty, &rdev->flags);
+		clear_bit(WriteMostly, &rdev->flags);
+		set_bit(In_sync, &rdev->flags);
+		sysfs_notify_dirent_safe(rdev->sysfs_state);
+	}
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_slot =
+__ATTR(slot, S_IRUGO|S_IWUSR, slot_show, slot_store);
+
+static ssize_t
+offset_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)rdev->data_offset);
+}
+
+static ssize_t
+offset_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	unsigned long long offset;
+	if (kstrtoull(buf, 10, &offset) < 0)
+		return -EINVAL;
+	if (rdev->mddev->pers && rdev->raid_disk >= 0)
+		return -EBUSY;
+	if (rdev->sectors && rdev->mddev->external)
+		/* Must set offset before size, so overlap checks
+		 * can be sane */
+		return -EBUSY;
+	rdev->data_offset = offset;
+	rdev->new_data_offset = offset;
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_offset =
+__ATTR(offset, S_IRUGO|S_IWUSR, offset_show, offset_store);
+
+static ssize_t new_offset_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)rdev->new_data_offset);
+}
+
+static ssize_t new_offset_store(struct md_rdev *rdev,
+				const char *buf, size_t len)
+{
+	unsigned long long new_offset;
+	struct mddev *mddev = rdev->mddev;
+
+	if (kstrtoull(buf, 10, &new_offset) < 0)
+		return -EINVAL;
+
+	if (mddev->sync_thread ||
+	    test_bit(MD_RECOVERY_RUNNING,&mddev->recovery))
+		return -EBUSY;
+	if (new_offset == rdev->data_offset)
+		/* reset is always permitted */
+		;
+	else if (new_offset > rdev->data_offset) {
+		/* must not push array size beyond rdev_sectors */
+		if (new_offset - rdev->data_offset
+		    + mddev->dev_sectors > rdev->sectors)
+				return -E2BIG;
+	}
+	/* Metadata worries about other space details. */
+
+	/* decreasing the offset is inconsistent with a backwards
+	 * reshape.
+	 */
+	if (new_offset < rdev->data_offset &&
+	    mddev->reshape_backwards)
+		return -EINVAL;
+	/* Increasing offset is inconsistent with forwards
+	 * reshape.  reshape_direction should be set to
+	 * 'backwards' first.
+	 */
+	if (new_offset > rdev->data_offset &&
+	    !mddev->reshape_backwards)
+		return -EINVAL;
+
+	if (mddev->pers && mddev->persistent &&
+	    !super_types[mddev->major_version]
+	    .allow_new_offset(rdev, new_offset))
+		return -E2BIG;
+	rdev->new_data_offset = new_offset;
+	if (new_offset > rdev->data_offset)
+		mddev->reshape_backwards = 1;
+	else if (new_offset < rdev->data_offset)
+		mddev->reshape_backwards = 0;
+
+	return len;
+}
+static struct rdev_sysfs_entry rdev_new_offset =
+__ATTR(new_offset, S_IRUGO|S_IWUSR, new_offset_show, new_offset_store);
+
+static ssize_t
+rdev_size_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)rdev->sectors / 2);
+}
+
+static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)
+{
+	/* check if two start/length pairs overlap */
+	if (s1+l1 <= s2)
+		return 0;
+	if (s2+l2 <= s1)
+		return 0;
+	return 1;
+}
+
+static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
+{
+	unsigned long long blocks;
+	sector_t new;
+
+	if (kstrtoull(buf, 10, &blocks) < 0)
+		return -EINVAL;
+
+	if (blocks & 1ULL << (8 * sizeof(blocks) - 1))
+		return -EINVAL; /* sector conversion overflow */
+
+	new = blocks * 2;
+	if (new != blocks * 2)
+		return -EINVAL; /* unsigned long long to sector_t overflow */
+
+	*sectors = new;
+	return 0;
+}
+
+static ssize_t
+rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	struct mddev *my_mddev = rdev->mddev;
+	sector_t oldsectors = rdev->sectors;
+	sector_t sectors;
+
+	if (strict_blocks_to_sectors(buf, &sectors) < 0)
+		return -EINVAL;
+	if (rdev->data_offset != rdev->new_data_offset)
+		return -EINVAL; /* too confusing */
+	if (my_mddev->pers && rdev->raid_disk >= 0) {
+		if (my_mddev->persistent) {
+			sectors = super_types[my_mddev->major_version].
+				rdev_size_change(rdev, sectors);
+			if (!sectors)
+				return -EBUSY;
+		} else if (!sectors)
+			sectors = (i_size_read(rdev->bdev->bd_inode) >> 9) -
+				rdev->data_offset;
+		if (!my_mddev->pers->resize)
+			/* Cannot change size for RAID0 or Linear etc */
+			return -EINVAL;
+	}
+	if (sectors < my_mddev->dev_sectors)
+		return -EINVAL; /* component must fit device */
+
+	rdev->sectors = sectors;
+	if (sectors > oldsectors && my_mddev->external) {
+		/* Need to check that all other rdevs with the same
+		 * ->bdev do not overlap.  'rcu' is sufficient to walk
+		 * the rdev lists safely.
+		 * This check does not provide a hard guarantee, it
+		 * just helps avoid dangerous mistakes.
+		 */
+		struct mddev *mddev;
+		int overlap = 0;
+		struct list_head *tmp;
+
+		rcu_read_lock();
+		for_each_mddev(mddev, tmp) {
+			struct md_rdev *rdev2;
+
+			rdev_for_each(rdev2, mddev)
+				if (rdev->bdev == rdev2->bdev &&
+				    rdev != rdev2 &&
+				    overlaps(rdev->data_offset, rdev->sectors,
+					     rdev2->data_offset,
+					     rdev2->sectors)) {
+					overlap = 1;
+					break;
+				}
+			if (overlap) {
+				mddev_put(mddev);
+				break;
+			}
+		}
+		rcu_read_unlock();
+		if (overlap) {
+			/* Someone else could have slipped in a size
+			 * change here, but doing so is just silly.
+			 * We put oldsectors back because we *know* it is
+			 * safe, and trust userspace not to race with
+			 * itself
+			 */
+			rdev->sectors = oldsectors;
+			return -EBUSY;
+		}
+	}
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_size =
+__ATTR(size, S_IRUGO|S_IWUSR, rdev_size_show, rdev_size_store);
+
+static ssize_t recovery_start_show(struct md_rdev *rdev, char *page)
+{
+	unsigned long long recovery_start = rdev->recovery_offset;
+
+	if (test_bit(In_sync, &rdev->flags) ||
+	    recovery_start == MaxSector)
+		return sprintf(page, "none\n");
+
+	return sprintf(page, "%llu\n", recovery_start);
+}
+
+static ssize_t recovery_start_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	unsigned long long recovery_start;
+
+	if (cmd_match(buf, "none"))
+		recovery_start = MaxSector;
+	else if (kstrtoull(buf, 10, &recovery_start))
+		return -EINVAL;
+
+	if (rdev->mddev->pers &&
+	    rdev->raid_disk >= 0)
+		return -EBUSY;
+
+	rdev->recovery_offset = recovery_start;
+	if (recovery_start == MaxSector)
+		set_bit(In_sync, &rdev->flags);
+	else
+		clear_bit(In_sync, &rdev->flags);
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_recovery_start =
+__ATTR(recovery_start, S_IRUGO|S_IWUSR, recovery_start_show, recovery_start_store);
+
+static ssize_t
+badblocks_show(struct badblocks *bb, char *page, int unack);
+static ssize_t
+badblocks_store(struct badblocks *bb, const char *page, size_t len, int unack);
+
+static ssize_t bb_show(struct md_rdev *rdev, char *page)
+{
+	return badblocks_show(&rdev->badblocks, page, 0);
+}
+static ssize_t bb_store(struct md_rdev *rdev, const char *page, size_t len)
+{
+	int rv = badblocks_store(&rdev->badblocks, page, len, 0);
+	/* Maybe that ack was all we needed */
+	if (test_and_clear_bit(BlockedBadBlocks, &rdev->flags))
+		wake_up(&rdev->blocked_wait);
+	return rv;
+}
+static struct rdev_sysfs_entry rdev_bad_blocks =
+__ATTR(bad_blocks, S_IRUGO|S_IWUSR, bb_show, bb_store);
+
+static ssize_t ubb_show(struct md_rdev *rdev, char *page)
+{
+	return badblocks_show(&rdev->badblocks, page, 1);
+}
+static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
+{
+	return badblocks_store(&rdev->badblocks, page, len, 1);
+}
+static struct rdev_sysfs_entry rdev_unack_bad_blocks =
+__ATTR(unacknowledged_bad_blocks, S_IRUGO|S_IWUSR, ubb_show, ubb_store);
+
+static struct attribute *rdev_default_attrs[] = {
+	&rdev_state.attr,
+	&rdev_errors.attr,
+	&rdev_slot.attr,
+	&rdev_offset.attr,
+	&rdev_new_offset.attr,
+	&rdev_size.attr,
+	&rdev_recovery_start.attr,
+	&rdev_bad_blocks.attr,
+	&rdev_unack_bad_blocks.attr,
+	NULL,
+};
+static ssize_t
+rdev_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+	struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
+	struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
+
+	if (!entry->show)
+		return -EIO;
+	if (!rdev->mddev)
+		return -EBUSY;
+	return entry->show(rdev, page);
+}
+
+static ssize_t
+rdev_attr_store(struct kobject *kobj, struct attribute *attr,
+	      const char *page, size_t length)
+{
+	struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
+	struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
+	ssize_t rv;
+	struct mddev *mddev = rdev->mddev;
+
+	if (!entry->store)
+		return -EIO;
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+	rv = mddev ? mddev_lock(mddev): -EBUSY;
+	if (!rv) {
+		if (rdev->mddev == NULL)
+			rv = -EBUSY;
+		else
+			rv = entry->store(rdev, page, length);
+		mddev_unlock(mddev);
+	}
+	return rv;
+}
+
+static void rdev_free(struct kobject *ko)
+{
+	struct md_rdev *rdev = container_of(ko, struct md_rdev, kobj);
+	kfree(rdev);
+}
+static const struct sysfs_ops rdev_sysfs_ops = {
+	.show		= rdev_attr_show,
+	.store		= rdev_attr_store,
+};
+static struct kobj_type rdev_ktype = {
+	.release	= rdev_free,
+	.sysfs_ops	= &rdev_sysfs_ops,
+	.default_attrs	= rdev_default_attrs,
+};
+
+int md_rdev_init(struct md_rdev *rdev)
+{
+	rdev->desc_nr = -1;
+	rdev->saved_raid_disk = -1;
+	rdev->raid_disk = -1;
+	rdev->flags = 0;
+	rdev->data_offset = 0;
+	rdev->new_data_offset = 0;
+	rdev->sb_events = 0;
+	rdev->last_read_error.tv_sec  = 0;
+	rdev->last_read_error.tv_nsec = 0;
+	rdev->sb_loaded = 0;
+	rdev->bb_page = NULL;
+	atomic_set(&rdev->nr_pending, 0);
+	atomic_set(&rdev->read_errors, 0);
+	atomic_set(&rdev->corrected_errors, 0);
+
+	INIT_LIST_HEAD(&rdev->same_set);
+	init_waitqueue_head(&rdev->blocked_wait);
+
+	/* Add space to store bad block list.
+	 * This reserves the space even on arrays where it cannot
+	 * be used - I wonder if that matters
+	 */
+	rdev->badblocks.count = 0;
+	rdev->badblocks.shift = -1; /* disabled until explicitly enabled */
+	rdev->badblocks.page = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	seqlock_init(&rdev->badblocks.lock);
+	if (rdev->badblocks.page == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(md_rdev_init);
+/*
+ * Import a device. If 'super_format' >= 0, then sanity check the superblock
+ *
+ * mark the device faulty if:
+ *
+ *   - the device is nonexistent (zero size)
+ *   - the device has no valid superblock
+ *
+ * a faulty rdev _never_ has rdev->sb set.
+ */
+static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor)
+{
+	char b[BDEVNAME_SIZE];
+	int err;
+	struct md_rdev *rdev;
+	sector_t size;
+
+	rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
+	if (!rdev) {
+		printk(KERN_ERR "md: could not alloc mem for new device!\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	err = md_rdev_init(rdev);
+	if (err)
+		goto abort_free;
+	err = alloc_disk_sb(rdev);
+	if (err)
+		goto abort_free;
+
+	err = lock_rdev(rdev, newdev, super_format == -2);
+	if (err)
+		goto abort_free;
+
+	kobject_init(&rdev->kobj, &rdev_ktype);
+
+	size = i_size_read(rdev->bdev->bd_inode) >> BLOCK_SIZE_BITS;
+	if (!size) {
+		printk(KERN_WARNING
+			"md: %s has zero or unknown size, marking faulty!\n",
+			bdevname(rdev->bdev,b));
+		err = -EINVAL;
+		goto abort_free;
+	}
+
+	if (super_format >= 0) {
+		err = super_types[super_format].
+			load_super(rdev, NULL, super_minor);
+		if (err == -EINVAL) {
+			printk(KERN_WARNING
+				"md: %s does not have a valid v%d.%d "
+			       "superblock, not importing!\n",
+				bdevname(rdev->bdev,b),
+			       super_format, super_minor);
+			goto abort_free;
+		}
+		if (err < 0) {
+			printk(KERN_WARNING
+				"md: could not read %s's sb, not importing!\n",
+				bdevname(rdev->bdev,b));
+			goto abort_free;
+		}
+	}
+
+	return rdev;
+
+abort_free:
+	if (rdev->bdev)
+		unlock_rdev(rdev);
+	md_rdev_clear(rdev);
+	kfree(rdev);
+	return ERR_PTR(err);
+}
+
+/*
+ * Check a full RAID array for plausibility
+ */
+
+static void analyze_sbs(struct mddev *mddev)
+{
+	int i;
+	struct md_rdev *rdev, *freshest, *tmp;
+	char b[BDEVNAME_SIZE];
+
+	freshest = NULL;
+	rdev_for_each_safe(rdev, tmp, mddev)
+		switch (super_types[mddev->major_version].
+			load_super(rdev, freshest, mddev->minor_version)) {
+		case 1:
+			freshest = rdev;
+			break;
+		case 0:
+			break;
+		default:
+			printk( KERN_ERR \
+				"md: fatal superblock inconsistency in %s"
+				" -- removing from array\n",
+				bdevname(rdev->bdev,b));
+			md_kick_rdev_from_array(rdev);
+		}
+
+	super_types[mddev->major_version].
+		validate_super(mddev, freshest);
+
+	i = 0;
+	rdev_for_each_safe(rdev, tmp, mddev) {
+		if (mddev->max_disks &&
+		    (rdev->desc_nr >= mddev->max_disks ||
+		     i > mddev->max_disks)) {
+			printk(KERN_WARNING
+			       "md: %s: %s: only %d devices permitted\n",
+			       mdname(mddev), bdevname(rdev->bdev, b),
+			       mddev->max_disks);
+			md_kick_rdev_from_array(rdev);
+			continue;
+		}
+		if (rdev != freshest) {
+			if (super_types[mddev->major_version].
+			    validate_super(mddev, rdev)) {
+				printk(KERN_WARNING "md: kicking non-fresh %s"
+					" from array!\n",
+					bdevname(rdev->bdev,b));
+				md_kick_rdev_from_array(rdev);
+				continue;
+			}
+			/* No device should have a Candidate flag
+			 * when reading devices
+			 */
+			if (test_bit(Candidate, &rdev->flags)) {
+				pr_info("md: kicking Cluster Candidate %s from array!\n",
+					bdevname(rdev->bdev, b));
+				md_kick_rdev_from_array(rdev);
+			}
+		}
+		if (mddev->level == LEVEL_MULTIPATH) {
+			rdev->desc_nr = i++;
+			rdev->raid_disk = rdev->desc_nr;
+			set_bit(In_sync, &rdev->flags);
+		} else if (rdev->raid_disk >= (mddev->raid_disks - min(0, mddev->delta_disks))) {
+			rdev->raid_disk = -1;
+			clear_bit(In_sync, &rdev->flags);
+		}
+	}
+}
+
+/* Read a fixed-point number.
+ * Numbers in sysfs attributes should be in "standard" units where
+ * possible, so time should be in seconds.
+ * However we internally use a a much smaller unit such as
+ * milliseconds or jiffies.
+ * This function takes a decimal number with a possible fractional
+ * component, and produces an integer which is the result of
+ * multiplying that number by 10^'scale'.
+ * all without any floating-point arithmetic.
+ */
+int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale)
+{
+	unsigned long result = 0;
+	long decimals = -1;
+	while (isdigit(*cp) || (*cp == '.' && decimals < 0)) {
+		if (*cp == '.')
+			decimals = 0;
+		else if (decimals < scale) {
+			unsigned int value;
+			value = *cp - '0';
+			result = result * 10 + value;
+			if (decimals >= 0)
+				decimals++;
+		}
+		cp++;
+	}
+	if (*cp == '\n')
+		cp++;
+	if (*cp)
+		return -EINVAL;
+	if (decimals < 0)
+		decimals = 0;
+	while (decimals < scale) {
+		result *= 10;
+		decimals ++;
+	}
+	*res = result;
+	return 0;
+}
+
+static void md_safemode_timeout(unsigned long data);
+
+static ssize_t
+safe_delay_show(struct mddev *mddev, char *page)
+{
+	int msec = (mddev->safemode_delay*1000)/HZ;
+	return sprintf(page, "%d.%03d\n", msec/1000, msec%1000);
+}
+static ssize_t
+safe_delay_store(struct mddev *mddev, const char *cbuf, size_t len)
+{
+	unsigned long msec;
+
+	if (strict_strtoul_scaled(cbuf, &msec, 3) < 0)
+		return -EINVAL;
+	if (msec == 0)
+		mddev->safemode_delay = 0;
+	else {
+		unsigned long old_delay = mddev->safemode_delay;
+		unsigned long new_delay = (msec*HZ)/1000;
+
+		if (new_delay == 0)
+			new_delay = 1;
+		mddev->safemode_delay = new_delay;
+		if (new_delay < old_delay || old_delay == 0)
+			mod_timer(&mddev->safemode_timer, jiffies+1);
+	}
+	return len;
+}
+static struct md_sysfs_entry md_safe_delay =
+__ATTR(safe_mode_delay, S_IRUGO|S_IWUSR,safe_delay_show, safe_delay_store);
+
+static ssize_t
+level_show(struct mddev *mddev, char *page)
+{
+	struct md_personality *p;
+	int ret;
+	spin_lock(&mddev->lock);
+	p = mddev->pers;
+	if (p)
+		ret = sprintf(page, "%s\n", p->name);
+	else if (mddev->clevel[0])
+		ret = sprintf(page, "%s\n", mddev->clevel);
+	else if (mddev->level != LEVEL_NONE)
+		ret = sprintf(page, "%d\n", mddev->level);
+	else
+		ret = 0;
+	spin_unlock(&mddev->lock);
+	return ret;
+}
+
+static ssize_t
+level_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char clevel[16];
+	ssize_t rv;
+	size_t slen = len;
+	struct md_personality *pers, *oldpers;
+	long level;
+	void *priv, *oldpriv;
+	struct md_rdev *rdev;
+
+	if (slen == 0 || slen >= sizeof(clevel))
+		return -EINVAL;
+
+	rv = mddev_lock(mddev);
+	if (rv)
+		return rv;
+
+	if (mddev->pers == NULL) {
+		strncpy(mddev->clevel, buf, slen);
+		if (mddev->clevel[slen-1] == '\n')
+			slen--;
+		mddev->clevel[slen] = 0;
+		mddev->level = LEVEL_NONE;
+		rv = len;
+		goto out_unlock;
+	}
+	rv = -EROFS;
+	if (mddev->ro)
+		goto out_unlock;
+
+	/* request to change the personality.  Need to ensure:
+	 *  - array is not engaged in resync/recovery/reshape
+	 *  - old personality can be suspended
+	 *  - new personality will access other array.
+	 */
+
+	rv = -EBUSY;
+	if (mddev->sync_thread ||
+	    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+	    mddev->reshape_position != MaxSector ||
+	    mddev->sysfs_active)
+		goto out_unlock;
+
+	rv = -EINVAL;
+	if (!mddev->pers->quiesce) {
+		printk(KERN_WARNING "md: %s: %s does not support online personality change\n",
+		       mdname(mddev), mddev->pers->name);
+		goto out_unlock;
+	}
+
+	/* Now find the new personality */
+	strncpy(clevel, buf, slen);
+	if (clevel[slen-1] == '\n')
+		slen--;
+	clevel[slen] = 0;
+	if (kstrtol(clevel, 10, &level))
+		level = LEVEL_NONE;
+
+	if (request_module("md-%s", clevel) != 0)
+		request_module("md-level-%s", clevel);
+	spin_lock(&pers_lock);
+	pers = find_pers(level, clevel);
+	if (!pers || !try_module_get(pers->owner)) {
+		spin_unlock(&pers_lock);
+		printk(KERN_WARNING "md: personality %s not loaded\n", clevel);
+		rv = -EINVAL;
+		goto out_unlock;
+	}
+	spin_unlock(&pers_lock);
+
+	if (pers == mddev->pers) {
+		/* Nothing to do! */
+		module_put(pers->owner);
+		rv = len;
+		goto out_unlock;
+	}
+	if (!pers->takeover) {
+		module_put(pers->owner);
+		printk(KERN_WARNING "md: %s: %s does not support personality takeover\n",
+		       mdname(mddev), clevel);
+		rv = -EINVAL;
+		goto out_unlock;
+	}
+
+	rdev_for_each(rdev, mddev)
+		rdev->new_raid_disk = rdev->raid_disk;
+
+	/* ->takeover must set new_* and/or delta_disks
+	 * if it succeeds, and may set them when it fails.
+	 */
+	priv = pers->takeover(mddev);
+	if (IS_ERR(priv)) {
+		mddev->new_level = mddev->level;
+		mddev->new_layout = mddev->layout;
+		mddev->new_chunk_sectors = mddev->chunk_sectors;
+		mddev->raid_disks -= mddev->delta_disks;
+		mddev->delta_disks = 0;
+		mddev->reshape_backwards = 0;
+		module_put(pers->owner);
+		printk(KERN_WARNING "md: %s: %s would not accept array\n",
+		       mdname(mddev), clevel);
+		rv = PTR_ERR(priv);
+		goto out_unlock;
+	}
+
+	/* Looks like we have a winner */
+	mddev_suspend(mddev);
+	mddev_detach(mddev);
+
+	spin_lock(&mddev->lock);
+	oldpers = mddev->pers;
+	oldpriv = mddev->private;
+	mddev->pers = pers;
+	mddev->private = priv;
+	strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
+	mddev->level = mddev->new_level;
+	mddev->layout = mddev->new_layout;
+	mddev->chunk_sectors = mddev->new_chunk_sectors;
+	mddev->delta_disks = 0;
+	mddev->reshape_backwards = 0;
+	mddev->degraded = 0;
+	spin_unlock(&mddev->lock);
+
+	if (oldpers->sync_request == NULL &&
+	    mddev->external) {
+		/* We are converting from a no-redundancy array
+		 * to a redundancy array and metadata is managed
+		 * externally so we need to be sure that writes
+		 * won't block due to a need to transition
+		 *      clean->dirty
+		 * until external management is started.
+		 */
+		mddev->in_sync = 0;
+		mddev->safemode_delay = 0;
+		mddev->safemode = 0;
+	}
+
+	oldpers->free(mddev, oldpriv);
+
+	if (oldpers->sync_request == NULL &&
+	    pers->sync_request != NULL) {
+		/* need to add the md_redundancy_group */
+		if (sysfs_create_group(&mddev->kobj, &md_redundancy_group))
+			printk(KERN_WARNING
+			       "md: cannot register extra attributes for %s\n",
+			       mdname(mddev));
+		mddev->sysfs_action = sysfs_get_dirent(mddev->kobj.sd, "sync_action");
+	}
+	if (oldpers->sync_request != NULL &&
+	    pers->sync_request == NULL) {
+		/* need to remove the md_redundancy_group */
+		if (mddev->to_remove == NULL)
+			mddev->to_remove = &md_redundancy_group;
+	}
+
+	rdev_for_each(rdev, mddev) {
+		if (rdev->raid_disk < 0)
+			continue;
+		if (rdev->new_raid_disk >= mddev->raid_disks)
+			rdev->new_raid_disk = -1;
+		if (rdev->new_raid_disk == rdev->raid_disk)
+			continue;
+		sysfs_unlink_rdev(mddev, rdev);
+	}
+	rdev_for_each(rdev, mddev) {
+		if (rdev->raid_disk < 0)
+			continue;
+		if (rdev->new_raid_disk == rdev->raid_disk)
+			continue;
+		rdev->raid_disk = rdev->new_raid_disk;
+		if (rdev->raid_disk < 0)
+			clear_bit(In_sync, &rdev->flags);
+		else {
+			if (sysfs_link_rdev(mddev, rdev))
+				printk(KERN_WARNING "md: cannot register rd%d"
+				       " for %s after level change\n",
+				       rdev->raid_disk, mdname(mddev));
+		}
+	}
+
+	if (pers->sync_request == NULL) {
+		/* this is now an array without redundancy, so
+		 * it must always be in_sync
+		 */
+		mddev->in_sync = 1;
+		del_timer_sync(&mddev->safemode_timer);
+	}
+	blk_set_stacking_limits(&mddev->queue->limits);
+	pers->run(mddev);
+	set_bit(MD_CHANGE_DEVS, &mddev->flags);
+	mddev_resume(mddev);
+	if (!mddev->thread)
+		md_update_sb(mddev, 1);
+	sysfs_notify(&mddev->kobj, NULL, "level");
+	md_new_event(mddev);
+	rv = len;
+out_unlock:
+	mddev_unlock(mddev);
+	return rv;
+}
+
+static struct md_sysfs_entry md_level =
+__ATTR(level, S_IRUGO|S_IWUSR, level_show, level_store);
+
+static ssize_t
+layout_show(struct mddev *mddev, char *page)
+{
+	/* just a number, not meaningful for all levels */
+	if (mddev->reshape_position != MaxSector &&
+	    mddev->layout != mddev->new_layout)
+		return sprintf(page, "%d (%d)\n",
+			       mddev->new_layout, mddev->layout);
+	return sprintf(page, "%d\n", mddev->layout);
+}
+
+static ssize_t
+layout_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char *e;
+	unsigned long n = simple_strtoul(buf, &e, 10);
+	int err;
+
+	if (!*buf || (*e && *e != '\n'))
+		return -EINVAL;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	if (mddev->pers) {
+		if (mddev->pers->check_reshape == NULL)
+			err = -EBUSY;
+		else if (mddev->ro)
+			err = -EROFS;
+		else {
+			mddev->new_layout = n;
+			err = mddev->pers->check_reshape(mddev);
+			if (err)
+				mddev->new_layout = mddev->layout;
+		}
+	} else {
+		mddev->new_layout = n;
+		if (mddev->reshape_position == MaxSector)
+			mddev->layout = n;
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_layout =
+__ATTR(layout, S_IRUGO|S_IWUSR, layout_show, layout_store);
+
+static ssize_t
+raid_disks_show(struct mddev *mddev, char *page)
+{
+	if (mddev->raid_disks == 0)
+		return 0;
+	if (mddev->reshape_position != MaxSector &&
+	    mddev->delta_disks != 0)
+		return sprintf(page, "%d (%d)\n", mddev->raid_disks,
+			       mddev->raid_disks - mddev->delta_disks);
+	return sprintf(page, "%d\n", mddev->raid_disks);
+}
+
+static int update_raid_disks(struct mddev *mddev, int raid_disks);
+
+static ssize_t
+raid_disks_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char *e;
+	int err;
+	unsigned long n = simple_strtoul(buf, &e, 10);
+
+	if (!*buf || (*e && *e != '\n'))
+		return -EINVAL;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->pers)
+		err = update_raid_disks(mddev, n);
+	else if (mddev->reshape_position != MaxSector) {
+		struct md_rdev *rdev;
+		int olddisks = mddev->raid_disks - mddev->delta_disks;
+
+		err = -EINVAL;
+		rdev_for_each(rdev, mddev) {
+			if (olddisks < n &&
+			    rdev->data_offset < rdev->new_data_offset)
+				goto out_unlock;
+			if (olddisks > n &&
+			    rdev->data_offset > rdev->new_data_offset)
+				goto out_unlock;
+		}
+		err = 0;
+		mddev->delta_disks = n - olddisks;
+		mddev->raid_disks = n;
+		mddev->reshape_backwards = (mddev->delta_disks < 0);
+	} else
+		mddev->raid_disks = n;
+out_unlock:
+	mddev_unlock(mddev);
+	return err ? err : len;
+}
+static struct md_sysfs_entry md_raid_disks =
+__ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);
+
+static ssize_t
+chunk_size_show(struct mddev *mddev, char *page)
+{
+	if (mddev->reshape_position != MaxSector &&
+	    mddev->chunk_sectors != mddev->new_chunk_sectors)
+		return sprintf(page, "%d (%d)\n",
+			       mddev->new_chunk_sectors << 9,
+			       mddev->chunk_sectors << 9);
+	return sprintf(page, "%d\n", mddev->chunk_sectors << 9);
+}
+
+static ssize_t
+chunk_size_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int err;
+	char *e;
+	unsigned long n = simple_strtoul(buf, &e, 10);
+
+	if (!*buf || (*e && *e != '\n'))
+		return -EINVAL;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->pers) {
+		if (mddev->pers->check_reshape == NULL)
+			err = -EBUSY;
+		else if (mddev->ro)
+			err = -EROFS;
+		else {
+			mddev->new_chunk_sectors = n >> 9;
+			err = mddev->pers->check_reshape(mddev);
+			if (err)
+				mddev->new_chunk_sectors = mddev->chunk_sectors;
+		}
+	} else {
+		mddev->new_chunk_sectors = n >> 9;
+		if (mddev->reshape_position == MaxSector)
+			mddev->chunk_sectors = n >> 9;
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_chunk_size =
+__ATTR(chunk_size, S_IRUGO|S_IWUSR, chunk_size_show, chunk_size_store);
+
+static ssize_t
+resync_start_show(struct mddev *mddev, char *page)
+{
+	if (mddev->recovery_cp == MaxSector)
+		return sprintf(page, "none\n");
+	return sprintf(page, "%llu\n", (unsigned long long)mddev->recovery_cp);
+}
+
+static ssize_t
+resync_start_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int err;
+	char *e;
+	unsigned long long n = simple_strtoull(buf, &e, 10);
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->pers && !test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+		err = -EBUSY;
+	else if (cmd_match(buf, "none"))
+		n = MaxSector;
+	else if (!*buf || (*e && *e != '\n'))
+		err = -EINVAL;
+
+	if (!err) {
+		mddev->recovery_cp = n;
+		if (mddev->pers)
+			set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_resync_start =
+__ATTR_PREALLOC(resync_start, S_IRUGO|S_IWUSR,
+		resync_start_show, resync_start_store);
+
+/*
+ * The array state can be:
+ *
+ * clear
+ *     No devices, no size, no level
+ *     Equivalent to STOP_ARRAY ioctl
+ * inactive
+ *     May have some settings, but array is not active
+ *        all IO results in error
+ *     When written, doesn't tear down array, but just stops it
+ * suspended (not supported yet)
+ *     All IO requests will block. The array can be reconfigured.
+ *     Writing this, if accepted, will block until array is quiescent
+ * readonly
+ *     no resync can happen.  no superblocks get written.
+ *     write requests fail
+ * read-auto
+ *     like readonly, but behaves like 'clean' on a write request.
+ *
+ * clean - no pending writes, but otherwise active.
+ *     When written to inactive array, starts without resync
+ *     If a write request arrives then
+ *       if metadata is known, mark 'dirty' and switch to 'active'.
+ *       if not known, block and switch to write-pending
+ *     If written to an active array that has pending writes, then fails.
+ * active
+ *     fully active: IO and resync can be happening.
+ *     When written to inactive array, starts with resync
+ *
+ * write-pending
+ *     clean, but writes are blocked waiting for 'active' to be written.
+ *
+ * active-idle
+ *     like active, but no writes have been seen for a while (100msec).
+ *
+ */
+enum array_state { clear, inactive, suspended, readonly, read_auto, clean, active,
+		   write_pending, active_idle, bad_word};
+static char *array_states[] = {
+	"clear", "inactive", "suspended", "readonly", "read-auto", "clean", "active",
+	"write-pending", "active-idle", NULL };
+
+static int match_word(const char *word, char **list)
+{
+	int n;
+	for (n=0; list[n]; n++)
+		if (cmd_match(word, list[n]))
+			break;
+	return n;
+}
+
+static ssize_t
+array_state_show(struct mddev *mddev, char *page)
+{
+	enum array_state st = inactive;
+
+	if (mddev->pers)
+		switch(mddev->ro) {
+		case 1:
+			st = readonly;
+			break;
+		case 2:
+			st = read_auto;
+			break;
+		case 0:
+			if (mddev->in_sync)
+				st = clean;
+			else if (test_bit(MD_CHANGE_PENDING, &mddev->flags))
+				st = write_pending;
+			else if (mddev->safemode)
+				st = active_idle;
+			else
+				st = active;
+		}
+	else {
+		if (list_empty(&mddev->disks) &&
+		    mddev->raid_disks == 0 &&
+		    mddev->dev_sectors == 0)
+			st = clear;
+		else
+			st = inactive;
+	}
+	return sprintf(page, "%s\n", array_states[st]);
+}
+
+static int do_md_stop(struct mddev *mddev, int ro, struct block_device *bdev);
+static int md_set_readonly(struct mddev *mddev, struct block_device *bdev);
+static int do_md_run(struct mddev *mddev);
+static int restart_array(struct mddev *mddev);
+
+static ssize_t
+array_state_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int err;
+	enum array_state st = match_word(buf, array_states);
+
+	if (mddev->pers && (st == active || st == clean) && mddev->ro != 1) {
+		/* don't take reconfig_mutex when toggling between
+		 * clean and active
+		 */
+		spin_lock(&mddev->lock);
+		if (st == active) {
+			restart_array(mddev);
+			clear_bit(MD_CHANGE_PENDING, &mddev->flags);
+			wake_up(&mddev->sb_wait);
+			err = 0;
+		} else /* st == clean */ {
+			restart_array(mddev);
+			if (atomic_read(&mddev->writes_pending) == 0) {
+				if (mddev->in_sync == 0) {
+					mddev->in_sync = 1;
+					if (mddev->safemode == 1)
+						mddev->safemode = 0;
+					set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+				}
+				err = 0;
+			} else
+				err = -EBUSY;
+		}
+		spin_unlock(&mddev->lock);
+		return err ?: len;
+	}
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	err = -EINVAL;
+	switch(st) {
+	case bad_word:
+		break;
+	case clear:
+		/* stopping an active array */
+		err = do_md_stop(mddev, 0, NULL);
+		break;
+	case inactive:
+		/* stopping an active array */
+		if (mddev->pers)
+			err = do_md_stop(mddev, 2, NULL);
+		else
+			err = 0; /* already inactive */
+		break;
+	case suspended:
+		break; /* not supported yet */
+	case readonly:
+		if (mddev->pers)
+			err = md_set_readonly(mddev, NULL);
+		else {
+			mddev->ro = 1;
+			set_disk_ro(mddev->gendisk, 1);
+			err = do_md_run(mddev);
+		}
+		break;
+	case read_auto:
+		if (mddev->pers) {
+			if (mddev->ro == 0)
+				err = md_set_readonly(mddev, NULL);
+			else if (mddev->ro == 1)
+				err = restart_array(mddev);
+			if (err == 0) {
+				mddev->ro = 2;
+				set_disk_ro(mddev->gendisk, 0);
+			}
+		} else {
+			mddev->ro = 2;
+			err = do_md_run(mddev);
+		}
+		break;
+	case clean:
+		if (mddev->pers) {
+			restart_array(mddev);
+			spin_lock(&mddev->lock);
+			if (atomic_read(&mddev->writes_pending) == 0) {
+				if (mddev->in_sync == 0) {
+					mddev->in_sync = 1;
+					if (mddev->safemode == 1)
+						mddev->safemode = 0;
+					set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+				}
+				err = 0;
+			} else
+				err = -EBUSY;
+			spin_unlock(&mddev->lock);
+		} else
+			err = -EINVAL;
+		break;
+	case active:
+		if (mddev->pers) {
+			restart_array(mddev);
+			clear_bit(MD_CHANGE_PENDING, &mddev->flags);
+			wake_up(&mddev->sb_wait);
+			err = 0;
+		} else {
+			mddev->ro = 0;
+			set_disk_ro(mddev->gendisk, 0);
+			err = do_md_run(mddev);
+		}
+		break;
+	case write_pending:
+	case active_idle:
+		/* these cannot be set */
+		break;
+	}
+
+	if (!err) {
+		if (mddev->hold_active == UNTIL_IOCTL)
+			mddev->hold_active = 0;
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_array_state =
+__ATTR_PREALLOC(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);
+
+static ssize_t
+max_corrected_read_errors_show(struct mddev *mddev, char *page) {
+	return sprintf(page, "%d\n",
+		       atomic_read(&mddev->max_corr_read_errors));
+}
+
+static ssize_t
+max_corrected_read_errors_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char *e;
+	unsigned long n = simple_strtoul(buf, &e, 10);
+
+	if (*buf && (*e == 0 || *e == '\n')) {
+		atomic_set(&mddev->max_corr_read_errors, n);
+		return len;
+	}
+	return -EINVAL;
+}
+
+static struct md_sysfs_entry max_corr_read_errors =
+__ATTR(max_read_errors, S_IRUGO|S_IWUSR, max_corrected_read_errors_show,
+	max_corrected_read_errors_store);
+
+static ssize_t
+null_show(struct mddev *mddev, char *page)
+{
+	return -EINVAL;
+}
+
+static ssize_t
+new_dev_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	/* buf must be %d:%d\n? giving major and minor numbers */
+	/* The new device is added to the array.
+	 * If the array has a persistent superblock, we read the
+	 * superblock to initialise info and check validity.
+	 * Otherwise, only checking done is that in bind_rdev_to_array,
+	 * which mainly checks size.
+	 */
+	char *e;
+	int major = simple_strtoul(buf, &e, 10);
+	int minor;
+	dev_t dev;
+	struct md_rdev *rdev;
+	int err;
+
+	if (!*buf || *e != ':' || !e[1] || e[1] == '\n')
+		return -EINVAL;
+	minor = simple_strtoul(e+1, &e, 10);
+	if (*e && *e != '\n')
+		return -EINVAL;
+	dev = MKDEV(major, minor);
+	if (major != MAJOR(dev) ||
+	    minor != MINOR(dev))
+		return -EOVERFLOW;
+
+	flush_workqueue(md_misc_wq);
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->persistent) {
+		rdev = md_import_device(dev, mddev->major_version,
+					mddev->minor_version);
+		if (!IS_ERR(rdev) && !list_empty(&mddev->disks)) {
+			struct md_rdev *rdev0
+				= list_entry(mddev->disks.next,
+					     struct md_rdev, same_set);
+			err = super_types[mddev->major_version]
+				.load_super(rdev, rdev0, mddev->minor_version);
+			if (err < 0)
+				goto out;
+		}
+	} else if (mddev->external)
+		rdev = md_import_device(dev, -2, -1);
+	else
+		rdev = md_import_device(dev, -1, -1);
+
+	if (IS_ERR(rdev)) {
+		mddev_unlock(mddev);
+		return PTR_ERR(rdev);
+	}
+	err = bind_rdev_to_array(rdev, mddev);
+ out:
+	if (err)
+		export_rdev(rdev);
+	mddev_unlock(mddev);
+	return err ? err : len;
+}
+
+static struct md_sysfs_entry md_new_device =
+__ATTR(new_dev, S_IWUSR, null_show, new_dev_store);
+
+static ssize_t
+bitmap_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char *end;
+	unsigned long chunk, end_chunk;
+	int err;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (!mddev->bitmap)
+		goto out;
+	/* buf should be <chunk> <chunk> ... or <chunk>-<chunk> ... (range) */
+	while (*buf) {
+		chunk = end_chunk = simple_strtoul(buf, &end, 0);
+		if (buf == end) break;
+		if (*end == '-') { /* range */
+			buf = end + 1;
+			end_chunk = simple_strtoul(buf, &end, 0);
+			if (buf == end) break;
+		}
+		if (*end && !isspace(*end)) break;
+		bitmap_dirty_bits(mddev->bitmap, chunk, end_chunk);
+		buf = skip_spaces(end);
+	}
+	bitmap_unplug(mddev->bitmap); /* flush the bits to disk */
+out:
+	mddev_unlock(mddev);
+	return len;
+}
+
+static struct md_sysfs_entry md_bitmap =
+__ATTR(bitmap_set_bits, S_IWUSR, null_show, bitmap_store);
+
+static ssize_t
+size_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		(unsigned long long)mddev->dev_sectors / 2);
+}
+
+static int update_size(struct mddev *mddev, sector_t num_sectors);
+
+static ssize_t
+size_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	/* If array is inactive, we can reduce the component size, but
+	 * not increase it (except from 0).
+	 * If array is active, we can try an on-line resize
+	 */
+	sector_t sectors;
+	int err = strict_blocks_to_sectors(buf, &sectors);
+
+	if (err < 0)
+		return err;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->pers) {
+		if (mddev_is_clustered(mddev))
+			md_cluster_ops->metadata_update_start(mddev);
+		err = update_size(mddev, sectors);
+		md_update_sb(mddev, 1);
+		if (mddev_is_clustered(mddev))
+			md_cluster_ops->metadata_update_finish(mddev);
+	} else {
+		if (mddev->dev_sectors == 0 ||
+		    mddev->dev_sectors > sectors)
+			mddev->dev_sectors = sectors;
+		else
+			err = -ENOSPC;
+	}
+	mddev_unlock(mddev);
+	return err ? err : len;
+}
+
+static struct md_sysfs_entry md_size =
+__ATTR(component_size, S_IRUGO|S_IWUSR, size_show, size_store);
+
+/* Metadata version.
+ * This is one of
+ *   'none' for arrays with no metadata (good luck...)
+ *   'external' for arrays with externally managed metadata,
+ * or N.M for internally known formats
+ */
+static ssize_t
+metadata_show(struct mddev *mddev, char *page)
+{
+	if (mddev->persistent)
+		return sprintf(page, "%d.%d\n",
+			       mddev->major_version, mddev->minor_version);
+	else if (mddev->external)
+		return sprintf(page, "external:%s\n", mddev->metadata_type);
+	else
+		return sprintf(page, "none\n");
+}
+
+static ssize_t
+metadata_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int major, minor;
+	char *e;
+	int err;
+	/* Changing the details of 'external' metadata is
+	 * always permitted.  Otherwise there must be
+	 * no devices attached to the array.
+	 */
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	err = -EBUSY;
+	if (mddev->external && strncmp(buf, "external:", 9) == 0)
+		;
+	else if (!list_empty(&mddev->disks))
+		goto out_unlock;
+
+	err = 0;
+	if (cmd_match(buf, "none")) {
+		mddev->persistent = 0;
+		mddev->external = 0;
+		mddev->major_version = 0;
+		mddev->minor_version = 90;
+		goto out_unlock;
+	}
+	if (strncmp(buf, "external:", 9) == 0) {
+		size_t namelen = len-9;
+		if (namelen >= sizeof(mddev->metadata_type))
+			namelen = sizeof(mddev->metadata_type)-1;
+		strncpy(mddev->metadata_type, buf+9, namelen);
+		mddev->metadata_type[namelen] = 0;
+		if (namelen && mddev->metadata_type[namelen-1] == '\n')
+			mddev->metadata_type[--namelen] = 0;
+		mddev->persistent = 0;
+		mddev->external = 1;
+		mddev->major_version = 0;
+		mddev->minor_version = 90;
+		goto out_unlock;
+	}
+	major = simple_strtoul(buf, &e, 10);
+	err = -EINVAL;
+	if (e==buf || *e != '.')
+		goto out_unlock;
+	buf = e+1;
+	minor = simple_strtoul(buf, &e, 10);
+	if (e==buf || (*e && *e != '\n') )
+		goto out_unlock;
+	err = -ENOENT;
+	if (major >= ARRAY_SIZE(super_types) || super_types[major].name == NULL)
+		goto out_unlock;
+	mddev->major_version = major;
+	mddev->minor_version = minor;
+	mddev->persistent = 1;
+	mddev->external = 0;
+	err = 0;
+out_unlock:
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_metadata =
+__ATTR_PREALLOC(metadata_version, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
+
+static ssize_t
+action_show(struct mddev *mddev, char *page)
+{
+	char *type = "idle";
+	unsigned long recovery = mddev->recovery;
+	if (test_bit(MD_RECOVERY_FROZEN, &recovery))
+		type = "frozen";
+	else if (test_bit(MD_RECOVERY_RUNNING, &recovery) ||
+	    (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &recovery))) {
+		if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
+			type = "reshape";
+		else if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
+			if (!test_bit(MD_RECOVERY_REQUESTED, &recovery))
+				type = "resync";
+			else if (test_bit(MD_RECOVERY_CHECK, &recovery))
+				type = "check";
+			else
+				type = "repair";
+		} else if (test_bit(MD_RECOVERY_RECOVER, &recovery))
+			type = "recover";
+	}
+	return sprintf(page, "%s\n", type);
+}
+
+static ssize_t
+action_store(struct mddev *mddev, const char *page, size_t len)
+{
+	if (!mddev->pers || !mddev->pers->sync_request)
+		return -EINVAL;
+
+
+	if (cmd_match(page, "idle") || cmd_match(page, "frozen")) {
+		if (cmd_match(page, "frozen"))
+			set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		else
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
+		    mddev_lock(mddev) == 0) {
+			flush_workqueue(md_misc_wq);
+			if (mddev->sync_thread) {
+				set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+				md_reap_sync_thread(mddev);
+			}
+			mddev_unlock(mddev);
+		}
+	} else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+		   test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
+		return -EBUSY;
+	else if (cmd_match(page, "resync"))
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	else if (cmd_match(page, "recover")) {
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+	} else if (cmd_match(page, "reshape")) {
+		int err;
+		if (mddev->pers->start_reshape == NULL)
+			return -EINVAL;
+		err = mddev_lock(mddev);
+		if (!err) {
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+			err = mddev->pers->start_reshape(mddev);
+			mddev_unlock(mddev);
+		}
+		if (err)
+			return err;
+		sysfs_notify(&mddev->kobj, NULL, "degraded");
+	} else {
+		if (cmd_match(page, "check"))
+			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+		else if (!cmd_match(page, "repair"))
+			return -EINVAL;
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+	}
+	if (mddev->ro == 2) {
+		/* A write to sync_action is enough to justify
+		 * canceling read-auto mode
+		 */
+		mddev->ro = 0;
+		md_wakeup_thread(mddev->sync_thread);
+	}
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+	return len;
+}
+
+static struct md_sysfs_entry md_scan_mode =
+__ATTR_PREALLOC(sync_action, S_IRUGO|S_IWUSR, action_show, action_store);
+
+static ssize_t
+last_sync_action_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%s\n", mddev->last_sync_action);
+}
+
+static struct md_sysfs_entry md_last_scan_mode = __ATTR_RO(last_sync_action);
+
+static ssize_t
+mismatch_cnt_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)
+		       atomic64_read(&mddev->resync_mismatches));
+}
+
+static struct md_sysfs_entry md_mismatches = __ATTR_RO(mismatch_cnt);
+
+static ssize_t
+sync_min_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d (%s)\n", speed_min(mddev),
+		       mddev->sync_speed_min ? "local": "system");
+}
+
+static ssize_t
+sync_min_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int min;
+	char *e;
+	if (strncmp(buf, "system", 6)==0) {
+		mddev->sync_speed_min = 0;
+		return len;
+	}
+	min = simple_strtoul(buf, &e, 10);
+	if (buf == e || (*e && *e != '\n') || min <= 0)
+		return -EINVAL;
+	mddev->sync_speed_min = min;
+	return len;
+}
+
+static struct md_sysfs_entry md_sync_min =
+__ATTR(sync_speed_min, S_IRUGO|S_IWUSR, sync_min_show, sync_min_store);
+
+static ssize_t
+sync_max_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d (%s)\n", speed_max(mddev),
+		       mddev->sync_speed_max ? "local": "system");
+}
+
+static ssize_t
+sync_max_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int max;
+	char *e;
+	if (strncmp(buf, "system", 6)==0) {
+		mddev->sync_speed_max = 0;
+		return len;
+	}
+	max = simple_strtoul(buf, &e, 10);
+	if (buf == e || (*e && *e != '\n') || max <= 0)
+		return -EINVAL;
+	mddev->sync_speed_max = max;
+	return len;
+}
+
+static struct md_sysfs_entry md_sync_max =
+__ATTR(sync_speed_max, S_IRUGO|S_IWUSR, sync_max_show, sync_max_store);
+
+static ssize_t
+degraded_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d\n", mddev->degraded);
+}
+static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);
+
+static ssize_t
+sync_force_parallel_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d\n", mddev->parallel_resync);
+}
+
+static ssize_t
+sync_force_parallel_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	long n;
+
+	if (kstrtol(buf, 10, &n))
+		return -EINVAL;
+
+	if (n != 0 && n != 1)
+		return -EINVAL;
+
+	mddev->parallel_resync = n;
+
+	if (mddev->sync_thread)
+		wake_up(&resync_wait);
+
+	return len;
+}
+
+/* force parallel resync, even with shared block devices */
+static struct md_sysfs_entry md_sync_force_parallel =
+__ATTR(sync_force_parallel, S_IRUGO|S_IWUSR,
+       sync_force_parallel_show, sync_force_parallel_store);
+
+static ssize_t
+sync_speed_show(struct mddev *mddev, char *page)
+{
+	unsigned long resync, dt, db;
+	if (mddev->curr_resync == 0)
+		return sprintf(page, "none\n");
+	resync = mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active);
+	dt = (jiffies - mddev->resync_mark) / HZ;
+	if (!dt) dt++;
+	db = resync - mddev->resync_mark_cnt;
+	return sprintf(page, "%lu\n", db/dt/2); /* K/sec */
+}
+
+static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);
+
+static ssize_t
+sync_completed_show(struct mddev *mddev, char *page)
+{
+	unsigned long long max_sectors, resync;
+
+	if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		return sprintf(page, "none\n");
+
+	if (mddev->curr_resync == 1 ||
+	    mddev->curr_resync == 2)
+		return sprintf(page, "delayed\n");
+
+	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
+	    test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		max_sectors = mddev->resync_max_sectors;
+	else
+		max_sectors = mddev->dev_sectors;
+
+	resync = mddev->curr_resync_completed;
+	return sprintf(page, "%llu / %llu\n", resync, max_sectors);
+}
+
+static struct md_sysfs_entry md_sync_completed =
+	__ATTR_PREALLOC(sync_completed, S_IRUGO, sync_completed_show, NULL);
+
+static ssize_t
+min_sync_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)mddev->resync_min);
+}
+static ssize_t
+min_sync_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned long long min;
+	int err;
+
+	if (kstrtoull(buf, 10, &min))
+		return -EINVAL;
+
+	spin_lock(&mddev->lock);
+	err = -EINVAL;
+	if (min > mddev->resync_max)
+		goto out_unlock;
+
+	err = -EBUSY;
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		goto out_unlock;
+
+	/* Round down to multiple of 4K for safety */
+	mddev->resync_min = round_down(min, 8);
+	err = 0;
+
+out_unlock:
+	spin_unlock(&mddev->lock);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_min_sync =
+__ATTR(sync_min, S_IRUGO|S_IWUSR, min_sync_show, min_sync_store);
+
+static ssize_t
+max_sync_show(struct mddev *mddev, char *page)
+{
+	if (mddev->resync_max == MaxSector)
+		return sprintf(page, "max\n");
+	else
+		return sprintf(page, "%llu\n",
+			       (unsigned long long)mddev->resync_max);
+}
+static ssize_t
+max_sync_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int err;
+	spin_lock(&mddev->lock);
+	if (strncmp(buf, "max", 3) == 0)
+		mddev->resync_max = MaxSector;
+	else {
+		unsigned long long max;
+		int chunk;
+
+		err = -EINVAL;
+		if (kstrtoull(buf, 10, &max))
+			goto out_unlock;
+		if (max < mddev->resync_min)
+			goto out_unlock;
+
+		err = -EBUSY;
+		if (max < mddev->resync_max &&
+		    mddev->ro == 0 &&
+		    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+			goto out_unlock;
+
+		/* Must be a multiple of chunk_size */
+		chunk = mddev->chunk_sectors;
+		if (chunk) {
+			sector_t temp = max;
+
+			err = -EINVAL;
+			if (sector_div(temp, chunk))
+				goto out_unlock;
+		}
+		mddev->resync_max = max;
+	}
+	wake_up(&mddev->recovery_wait);
+	err = 0;
+out_unlock:
+	spin_unlock(&mddev->lock);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_max_sync =
+__ATTR(sync_max, S_IRUGO|S_IWUSR, max_sync_show, max_sync_store);
+
+static ssize_t
+suspend_lo_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
+}
+
+static ssize_t
+suspend_lo_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char *e;
+	unsigned long long new = simple_strtoull(buf, &e, 10);
+	unsigned long long old;
+	int err;
+
+	if (buf == e || (*e && *e != '\n'))
+		return -EINVAL;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	err = -EINVAL;
+	if (mddev->pers == NULL ||
+	    mddev->pers->quiesce == NULL)
+		goto unlock;
+	old = mddev->suspend_lo;
+	mddev->suspend_lo = new;
+	if (new >= old)
+		/* Shrinking suspended region */
+		mddev->pers->quiesce(mddev, 2);
+	else {
+		/* Expanding suspended region - need to wait */
+		mddev->pers->quiesce(mddev, 1);
+		mddev->pers->quiesce(mddev, 0);
+	}
+	err = 0;
+unlock:
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_suspend_lo =
+__ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);
+
+static ssize_t
+suspend_hi_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
+}
+
+static ssize_t
+suspend_hi_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char *e;
+	unsigned long long new = simple_strtoull(buf, &e, 10);
+	unsigned long long old;
+	int err;
+
+	if (buf == e || (*e && *e != '\n'))
+		return -EINVAL;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	err = -EINVAL;
+	if (mddev->pers == NULL ||
+	    mddev->pers->quiesce == NULL)
+		goto unlock;
+	old = mddev->suspend_hi;
+	mddev->suspend_hi = new;
+	if (new <= old)
+		/* Shrinking suspended region */
+		mddev->pers->quiesce(mddev, 2);
+	else {
+		/* Expanding suspended region - need to wait */
+		mddev->pers->quiesce(mddev, 1);
+		mddev->pers->quiesce(mddev, 0);
+	}
+	err = 0;
+unlock:
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_suspend_hi =
+__ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);
+
+static ssize_t
+reshape_position_show(struct mddev *mddev, char *page)
+{
+	if (mddev->reshape_position != MaxSector)
+		return sprintf(page, "%llu\n",
+			       (unsigned long long)mddev->reshape_position);
+	strcpy(page, "none\n");
+	return 5;
+}
+
+static ssize_t
+reshape_position_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	struct md_rdev *rdev;
+	char *e;
+	int err;
+	unsigned long long new = simple_strtoull(buf, &e, 10);
+
+	if (buf == e || (*e && *e != '\n'))
+		return -EINVAL;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	err = -EBUSY;
+	if (mddev->pers)
+		goto unlock;
+	mddev->reshape_position = new;
+	mddev->delta_disks = 0;
+	mddev->reshape_backwards = 0;
+	mddev->new_level = mddev->level;
+	mddev->new_layout = mddev->layout;
+	mddev->new_chunk_sectors = mddev->chunk_sectors;
+	rdev_for_each(rdev, mddev)
+		rdev->new_data_offset = rdev->data_offset;
+	err = 0;
+unlock:
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_reshape_position =
+__ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
+       reshape_position_store);
+
+static ssize_t
+reshape_direction_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%s\n",
+		       mddev->reshape_backwards ? "backwards" : "forwards");
+}
+
+static ssize_t
+reshape_direction_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int backwards = 0;
+	int err;
+
+	if (cmd_match(buf, "forwards"))
+		backwards = 0;
+	else if (cmd_match(buf, "backwards"))
+		backwards = 1;
+	else
+		return -EINVAL;
+	if (mddev->reshape_backwards == backwards)
+		return len;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	/* check if we are allowed to change */
+	if (mddev->delta_disks)
+		err = -EBUSY;
+	else if (mddev->persistent &&
+	    mddev->major_version == 0)
+		err =  -EINVAL;
+	else
+		mddev->reshape_backwards = backwards;
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_reshape_direction =
+__ATTR(reshape_direction, S_IRUGO|S_IWUSR, reshape_direction_show,
+       reshape_direction_store);
+
+static ssize_t
+array_size_show(struct mddev *mddev, char *page)
+{
+	if (mddev->external_size)
+		return sprintf(page, "%llu\n",
+			       (unsigned long long)mddev->array_sectors/2);
+	else
+		return sprintf(page, "default\n");
+}
+
+static ssize_t
+array_size_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	sector_t sectors;
+	int err;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	if (strncmp(buf, "default", 7) == 0) {
+		if (mddev->pers)
+			sectors = mddev->pers->size(mddev, 0, 0);
+		else
+			sectors = mddev->array_sectors;
+
+		mddev->external_size = 0;
+	} else {
+		if (strict_blocks_to_sectors(buf, &sectors) < 0)
+			err = -EINVAL;
+		else if (mddev->pers && mddev->pers->size(mddev, 0, 0) < sectors)
+			err = -E2BIG;
+		else
+			mddev->external_size = 1;
+	}
+
+	if (!err) {
+		mddev->array_sectors = sectors;
+		if (mddev->pers) {
+			set_capacity(mddev->gendisk, mddev->array_sectors);
+			revalidate_disk(mddev->gendisk);
+		}
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_array_size =
+__ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
+       array_size_store);
+
+static struct attribute *md_default_attrs[] = {
+	&md_level.attr,
+	&md_layout.attr,
+	&md_raid_disks.attr,
+	&md_chunk_size.attr,
+	&md_size.attr,
+	&md_resync_start.attr,
+	&md_metadata.attr,
+	&md_new_device.attr,
+	&md_safe_delay.attr,
+	&md_array_state.attr,
+	&md_reshape_position.attr,
+	&md_reshape_direction.attr,
+	&md_array_size.attr,
+	&max_corr_read_errors.attr,
+	NULL,
+};
+
+static struct attribute *md_redundancy_attrs[] = {
+	&md_scan_mode.attr,
+	&md_last_scan_mode.attr,
+	&md_mismatches.attr,
+	&md_sync_min.attr,
+	&md_sync_max.attr,
+	&md_sync_speed.attr,
+	&md_sync_force_parallel.attr,
+	&md_sync_completed.attr,
+	&md_min_sync.attr,
+	&md_max_sync.attr,
+	&md_suspend_lo.attr,
+	&md_suspend_hi.attr,
+	&md_bitmap.attr,
+	&md_degraded.attr,
+	NULL,
+};
+static struct attribute_group md_redundancy_group = {
+	.name = NULL,
+	.attrs = md_redundancy_attrs,
+};
+
+static ssize_t
+md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+	struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
+	struct mddev *mddev = container_of(kobj, struct mddev, kobj);
+	ssize_t rv;
+
+	if (!entry->show)
+		return -EIO;
+	spin_lock(&all_mddevs_lock);
+	if (list_empty(&mddev->all_mddevs)) {
+		spin_unlock(&all_mddevs_lock);
+		return -EBUSY;
+	}
+	mddev_get(mddev);
+	spin_unlock(&all_mddevs_lock);
+
+	rv = entry->show(mddev, page);
+	mddev_put(mddev);
+	return rv;
+}
+
+static ssize_t
+md_attr_store(struct kobject *kobj, struct attribute *attr,
+	      const char *page, size_t length)
+{
+	struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
+	struct mddev *mddev = container_of(kobj, struct mddev, kobj);
+	ssize_t rv;
+
+	if (!entry->store)
+		return -EIO;
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+	spin_lock(&all_mddevs_lock);
+	if (list_empty(&mddev->all_mddevs)) {
+		spin_unlock(&all_mddevs_lock);
+		return -EBUSY;
+	}
+	mddev_get(mddev);
+	spin_unlock(&all_mddevs_lock);
+	rv = entry->store(mddev, page, length);
+	mddev_put(mddev);
+	return rv;
+}
+
+static void md_free(struct kobject *ko)
+{
+	struct mddev *mddev = container_of(ko, struct mddev, kobj);
+
+	if (mddev->sysfs_state)
+		sysfs_put(mddev->sysfs_state);
+
+	if (mddev->queue)
+		blk_cleanup_queue(mddev->queue);
+	if (mddev->gendisk) {
+		del_gendisk(mddev->gendisk);
+		put_disk(mddev->gendisk);
+	}
+
+	kfree(mddev);
+}
+
+static const struct sysfs_ops md_sysfs_ops = {
+	.show	= md_attr_show,
+	.store	= md_attr_store,
+};
+static struct kobj_type md_ktype = {
+	.release	= md_free,
+	.sysfs_ops	= &md_sysfs_ops,
+	.default_attrs	= md_default_attrs,
+};
+
+int mdp_major = 0;
+
+static void mddev_delayed_delete(struct work_struct *ws)
+{
+	struct mddev *mddev = container_of(ws, struct mddev, del_work);
+
+	sysfs_remove_group(&mddev->kobj, &md_bitmap_group);
+	kobject_del(&mddev->kobj);
+	kobject_put(&mddev->kobj);
+}
+
+static int md_alloc(dev_t dev, char *name)
+{
+	static DEFINE_MUTEX(disks_mutex);
+	struct mddev *mddev = mddev_find(dev);
+	struct gendisk *disk;
+	int partitioned;
+	int shift;
+	int unit;
+	int error;
+
+	if (!mddev)
+		return -ENODEV;
+
+	partitioned = (MAJOR(mddev->unit) != MD_MAJOR);
+	shift = partitioned ? MdpMinorShift : 0;
+	unit = MINOR(mddev->unit) >> shift;
+
+	/* wait for any previous instance of this device to be
+	 * completely removed (mddev_delayed_delete).
+	 */
+	flush_workqueue(md_misc_wq);
+
+	mutex_lock(&disks_mutex);
+	error = -EEXIST;
+	if (mddev->gendisk)
+		goto abort;
+
+	if (name) {
+		/* Need to ensure that 'name' is not a duplicate.
+		 */
+		struct mddev *mddev2;
+		spin_lock(&all_mddevs_lock);
+
+		list_for_each_entry(mddev2, &all_mddevs, all_mddevs)
+			if (mddev2->gendisk &&
+			    strcmp(mddev2->gendisk->disk_name, name) == 0) {
+				spin_unlock(&all_mddevs_lock);
+				goto abort;
+			}
+		spin_unlock(&all_mddevs_lock);
+	}
+
+	error = -ENOMEM;
+	mddev->queue = blk_alloc_queue(GFP_KERNEL);
+	if (!mddev->queue)
+		goto abort;
+	mddev->queue->queuedata = mddev;
+
+	blk_queue_make_request(mddev->queue, md_make_request);
+	blk_set_stacking_limits(&mddev->queue->limits);
+
+	disk = alloc_disk(1 << shift);
+	if (!disk) {
+		blk_cleanup_queue(mddev->queue);
+		mddev->queue = NULL;
+		goto abort;
+	}
+	disk->major = MAJOR(mddev->unit);
+	disk->first_minor = unit << shift;
+	if (name)
+		strcpy(disk->disk_name, name);
+	else if (partitioned)
+		sprintf(disk->disk_name, "md_d%d", unit);
+	else
+		sprintf(disk->disk_name, "md%d", unit);
+	disk->fops = &md_fops;
+	disk->private_data = mddev;
+	disk->queue = mddev->queue;
+	blk_queue_flush(mddev->queue, REQ_FLUSH | REQ_FUA);
+	/* Allow extended partitions.  This makes the
+	 * 'mdp' device redundant, but we can't really
+	 * remove it now.
+	 */
+	disk->flags |= GENHD_FL_EXT_DEVT;
+	mddev->gendisk = disk;
+	/* As soon as we call add_disk(), another thread could get
+	 * through to md_open, so make sure it doesn't get too far
+	 */
+	mutex_lock(&mddev->open_mutex);
+	add_disk(disk);
+
+	error = kobject_init_and_add(&mddev->kobj, &md_ktype,
+				     &disk_to_dev(disk)->kobj, "%s", "md");
+	if (error) {
+		/* This isn't possible, but as kobject_init_and_add is marked
+		 * __must_check, we must do something with the result
+		 */
+		printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
+		       disk->disk_name);
+		error = 0;
+	}
+	if (mddev->kobj.sd &&
+	    sysfs_create_group(&mddev->kobj, &md_bitmap_group))
+		printk(KERN_DEBUG "pointless warning\n");
+	mutex_unlock(&mddev->open_mutex);
+ abort:
+	mutex_unlock(&disks_mutex);
+	if (!error && mddev->kobj.sd) {
+		kobject_uevent(&mddev->kobj, KOBJ_ADD);
+		mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
+	}
+	mddev_put(mddev);
+	return error;
+}
+
+static struct kobject *md_probe(dev_t dev, int *part, void *data)
+{
+	md_alloc(dev, NULL);
+	return NULL;
+}
+
+static int add_named_array(const char *val, struct kernel_param *kp)
+{
+	/* val must be "md_*" where * is not all digits.
+	 * We allocate an array with a large free minor number, and
+	 * set the name to val.  val must not already be an active name.
+	 */
+	int len = strlen(val);
+	char buf[DISK_NAME_LEN];
+
+	while (len && val[len-1] == '\n')
+		len--;
+	if (len >= DISK_NAME_LEN)
+		return -E2BIG;
+	strlcpy(buf, val, len+1);
+	if (strncmp(buf, "md_", 3) != 0)
+		return -EINVAL;
+	return md_alloc(0, buf);
+}
+
+static void md_safemode_timeout(unsigned long data)
+{
+	struct mddev *mddev = (struct mddev *) data;
+
+	if (!atomic_read(&mddev->writes_pending)) {
+		mddev->safemode = 1;
+		if (mddev->external)
+			sysfs_notify_dirent_safe(mddev->sysfs_state);
+	}
+	md_wakeup_thread(mddev->thread);
+}
+
+static int start_dirty_degraded;
+
+int md_run(struct mddev *mddev)
+{
+	int err;
+	struct md_rdev *rdev;
+	struct md_personality *pers;
+
+	if (list_empty(&mddev->disks))
+		/* cannot run an array with no devices.. */
+		return -EINVAL;
+
+	if (mddev->pers)
+		return -EBUSY;
+	/* Cannot run until previous stop completes properly */
+	if (mddev->sysfs_active)
+		return -EBUSY;
+
+	/*
+	 * Analyze all RAID superblock(s)
+	 */
+	if (!mddev->raid_disks) {
+		if (!mddev->persistent)
+			return -EINVAL;
+		analyze_sbs(mddev);
+	}
+
+	if (mddev->level != LEVEL_NONE)
+		request_module("md-level-%d", mddev->level);
+	else if (mddev->clevel[0])
+		request_module("md-%s", mddev->clevel);
+
+	/*
+	 * Drop all container device buffers, from now on
+	 * the only valid external interface is through the md
+	 * device.
+	 */
+	rdev_for_each(rdev, mddev) {
+		if (test_bit(Faulty, &rdev->flags))
+			continue;
+		sync_blockdev(rdev->bdev);
+		invalidate_bdev(rdev->bdev);
+
+		/* perform some consistency tests on the device.
+		 * We don't want the data to overlap the metadata,
+		 * Internal Bitmap issues have been handled elsewhere.
+		 */
+		if (rdev->meta_bdev) {
+			/* Nothing to check */;
+		} else if (rdev->data_offset < rdev->sb_start) {
+			if (mddev->dev_sectors &&
+			    rdev->data_offset + mddev->dev_sectors
+			    > rdev->sb_start) {
+				printk("md: %s: data overlaps metadata\n",
+				       mdname(mddev));
+				return -EINVAL;
+			}
+		} else {
+			if (rdev->sb_start + rdev->sb_size/512
+			    > rdev->data_offset) {
+				printk("md: %s: metadata overlaps data\n",
+				       mdname(mddev));
+				return -EINVAL;
+			}
+		}
+		sysfs_notify_dirent_safe(rdev->sysfs_state);
+	}
+
+	if (mddev->bio_set == NULL)
+		mddev->bio_set = bioset_create(BIO_POOL_SIZE, 0);
+
+	spin_lock(&pers_lock);
+	pers = find_pers(mddev->level, mddev->clevel);
+	if (!pers || !try_module_get(pers->owner)) {
+		spin_unlock(&pers_lock);
+		if (mddev->level != LEVEL_NONE)
+			printk(KERN_WARNING "md: personality for level %d is not loaded!\n",
+			       mddev->level);
+		else
+			printk(KERN_WARNING "md: personality for level %s is not loaded!\n",
+			       mddev->clevel);
+		return -EINVAL;
+	}
+	spin_unlock(&pers_lock);
+	if (mddev->level != pers->level) {
+		mddev->level = pers->level;
+		mddev->new_level = pers->level;
+	}
+	strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
+
+	if (mddev->reshape_position != MaxSector &&
+	    pers->start_reshape == NULL) {
+		/* This personality cannot handle reshaping... */
+		module_put(pers->owner);
+		return -EINVAL;
+	}
+
+	if (pers->sync_request) {
+		/* Warn if this is a potentially silly
+		 * configuration.
+		 */
+		char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
+		struct md_rdev *rdev2;
+		int warned = 0;
+
+		rdev_for_each(rdev, mddev)
+			rdev_for_each(rdev2, mddev) {
+				if (rdev < rdev2 &&
+				    rdev->bdev->bd_contains ==
+				    rdev2->bdev->bd_contains) {
+					printk(KERN_WARNING
+					       "%s: WARNING: %s appears to be"
+					       " on the same physical disk as"
+					       " %s.\n",
+					       mdname(mddev),
+					       bdevname(rdev->bdev,b),
+					       bdevname(rdev2->bdev,b2));
+					warned = 1;
+				}
+			}
+
+		if (warned)
+			printk(KERN_WARNING
+			       "True protection against single-disk"
+			       " failure might be compromised.\n");
+	}
+
+	mddev->recovery = 0;
+	/* may be over-ridden by personality */
+	mddev->resync_max_sectors = mddev->dev_sectors;
+
+	mddev->ok_start_degraded = start_dirty_degraded;
+
+	if (start_readonly && mddev->ro == 0)
+		mddev->ro = 2; /* read-only, but switch on first write */
+
+	err = pers->run(mddev);
+	if (err)
+		printk(KERN_ERR "md: pers->run() failed ...\n");
+	else if (pers->size(mddev, 0, 0) < mddev->array_sectors) {
+		WARN_ONCE(!mddev->external_size, "%s: default size too small,"
+			  " but 'external_size' not in effect?\n", __func__);
+		printk(KERN_ERR
+		       "md: invalid array_size %llu > default size %llu\n",
+		       (unsigned long long)mddev->array_sectors / 2,
+		       (unsigned long long)pers->size(mddev, 0, 0) / 2);
+		err = -EINVAL;
+	}
+	if (err == 0 && pers->sync_request &&
+	    (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
+		struct bitmap *bitmap;
+
+		bitmap = bitmap_create(mddev, -1);
+		if (IS_ERR(bitmap)) {
+			err = PTR_ERR(bitmap);
+			printk(KERN_ERR "%s: failed to create bitmap (%d)\n",
+			       mdname(mddev), err);
+		} else
+			mddev->bitmap = bitmap;
+
+	}
+	if (err) {
+		mddev_detach(mddev);
+		if (mddev->private)
+			pers->free(mddev, mddev->private);
+		mddev->private = NULL;
+		module_put(pers->owner);
+		bitmap_destroy(mddev);
+		return err;
+	}
+	if (mddev->queue) {
+		mddev->queue->backing_dev_info.congested_data = mddev;
+		mddev->queue->backing_dev_info.congested_fn = md_congested;
+		blk_queue_merge_bvec(mddev->queue, md_mergeable_bvec);
+	}
+	if (pers->sync_request) {
+		if (mddev->kobj.sd &&
+		    sysfs_create_group(&mddev->kobj, &md_redundancy_group))
+			printk(KERN_WARNING
+			       "md: cannot register extra attributes for %s\n",
+			       mdname(mddev));
+		mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
+	} else if (mddev->ro == 2) /* auto-readonly not meaningful */
+		mddev->ro = 0;
+
+	atomic_set(&mddev->writes_pending,0);
+	atomic_set(&mddev->max_corr_read_errors,
+		   MD_DEFAULT_MAX_CORRECTED_READ_ERRORS);
+	mddev->safemode = 0;
+	mddev->safemode_timer.function = md_safemode_timeout;
+	mddev->safemode_timer.data = (unsigned long) mddev;
+	mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */
+	mddev->in_sync = 1;
+	smp_wmb();
+	spin_lock(&mddev->lock);
+	mddev->pers = pers;
+	mddev->ready = 1;
+	spin_unlock(&mddev->lock);
+	rdev_for_each(rdev, mddev)
+		if (rdev->raid_disk >= 0)
+			if (sysfs_link_rdev(mddev, rdev))
+				/* failure here is OK */;
+
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+
+	if (mddev->flags & MD_UPDATE_SB_FLAGS)
+		md_update_sb(mddev, 0);
+
+	md_new_event(mddev);
+	sysfs_notify_dirent_safe(mddev->sysfs_state);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+	sysfs_notify(&mddev->kobj, NULL, "degraded");
+	return 0;
+}
+EXPORT_SYMBOL_GPL(md_run);
+
+static int do_md_run(struct mddev *mddev)
+{
+	int err;
+
+	err = md_run(mddev);
+	if (err)
+		goto out;
+	err = bitmap_load(mddev);
+	if (err) {
+		bitmap_destroy(mddev);
+		goto out;
+	}
+
+	md_wakeup_thread(mddev->thread);
+	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
+
+	set_capacity(mddev->gendisk, mddev->array_sectors);
+	revalidate_disk(mddev->gendisk);
+	mddev->changed = 1;
+	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
+out:
+	return err;
+}
+
+static int restart_array(struct mddev *mddev)
+{
+	struct gendisk *disk = mddev->gendisk;
+
+	/* Complain if it has no devices */
+	if (list_empty(&mddev->disks))
+		return -ENXIO;
+	if (!mddev->pers)
+		return -EINVAL;
+	if (!mddev->ro)
+		return -EBUSY;
+	mddev->safemode = 0;
+	mddev->ro = 0;
+	set_disk_ro(disk, 0);
+	printk(KERN_INFO "md: %s switched to read-write mode.\n",
+		mdname(mddev));
+	/* Kick recovery or resync if necessary */
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	md_wakeup_thread(mddev->sync_thread);
+	sysfs_notify_dirent_safe(mddev->sysfs_state);
+	return 0;
+}
+
+static void md_clean(struct mddev *mddev)
+{
+	mddev->array_sectors = 0;
+	mddev->external_size = 0;
+	mddev->dev_sectors = 0;
+	mddev->raid_disks = 0;
+	mddev->recovery_cp = 0;
+	mddev->resync_min = 0;
+	mddev->resync_max = MaxSector;
+	mddev->reshape_position = MaxSector;
+	mddev->external = 0;
+	mddev->persistent = 0;
+	mddev->level = LEVEL_NONE;
+	mddev->clevel[0] = 0;
+	mddev->flags = 0;
+	mddev->ro = 0;
+	mddev->metadata_type[0] = 0;
+	mddev->chunk_sectors = 0;
+	mddev->ctime = mddev->utime = 0;
+	mddev->layout = 0;
+	mddev->max_disks = 0;
+	mddev->events = 0;
+	mddev->can_decrease_events = 0;
+	mddev->delta_disks = 0;
+	mddev->reshape_backwards = 0;
+	mddev->new_level = LEVEL_NONE;
+	mddev->new_layout = 0;
+	mddev->new_chunk_sectors = 0;
+	mddev->curr_resync = 0;
+	atomic64_set(&mddev->resync_mismatches, 0);
+	mddev->suspend_lo = mddev->suspend_hi = 0;
+	mddev->sync_speed_min = mddev->sync_speed_max = 0;
+	mddev->recovery = 0;
+	mddev->in_sync = 0;
+	mddev->changed = 0;
+	mddev->degraded = 0;
+	mddev->safemode = 0;
+	mddev->private = NULL;
+	mddev->merge_check_needed = 0;
+	mddev->bitmap_info.offset = 0;
+	mddev->bitmap_info.default_offset = 0;
+	mddev->bitmap_info.default_space = 0;
+	mddev->bitmap_info.chunksize = 0;
+	mddev->bitmap_info.daemon_sleep = 0;
+	mddev->bitmap_info.max_write_behind = 0;
+}
+
+static void __md_stop_writes(struct mddev *mddev)
+{
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_start(mddev);
+	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	flush_workqueue(md_misc_wq);
+	if (mddev->sync_thread) {
+		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+		md_reap_sync_thread(mddev);
+	}
+
+	del_timer_sync(&mddev->safemode_timer);
+
+	bitmap_flush(mddev);
+	md_super_wait(mddev);
+
+	if (mddev->ro == 0 &&
+	    (!mddev->in_sync || (mddev->flags & MD_UPDATE_SB_FLAGS))) {
+		/* mark array as shutdown cleanly */
+		mddev->in_sync = 1;
+		md_update_sb(mddev, 1);
+	}
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_finish(mddev);
+}
+
+void md_stop_writes(struct mddev *mddev)
+{
+	mddev_lock_nointr(mddev);
+	__md_stop_writes(mddev);
+	mddev_unlock(mddev);
+}
+EXPORT_SYMBOL_GPL(md_stop_writes);
+
+static void mddev_detach(struct mddev *mddev)
+{
+	struct bitmap *bitmap = mddev->bitmap;
+	/* wait for behind writes to complete */
+	if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
+		printk(KERN_INFO "md:%s: behind writes in progress - waiting to stop.\n",
+		       mdname(mddev));
+		/* need to kick something here to make sure I/O goes? */
+		wait_event(bitmap->behind_wait,
+			   atomic_read(&bitmap->behind_writes) == 0);
+	}
+	if (mddev->pers && mddev->pers->quiesce) {
+		mddev->pers->quiesce(mddev, 1);
+		mddev->pers->quiesce(mddev, 0);
+	}
+	md_unregister_thread(&mddev->thread);
+	if (mddev->queue)
+		blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
+}
+
+static void __md_stop(struct mddev *mddev)
+{
+	struct md_personality *pers = mddev->pers;
+	mddev_detach(mddev);
+	spin_lock(&mddev->lock);
+	mddev->ready = 0;
+	mddev->pers = NULL;
+	spin_unlock(&mddev->lock);
+	pers->free(mddev, mddev->private);
+	mddev->private = NULL;
+	if (pers->sync_request && mddev->to_remove == NULL)
+		mddev->to_remove = &md_redundancy_group;
+	module_put(pers->owner);
+	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+}
+
+void md_stop(struct mddev *mddev)
+{
+	/* stop the array and free an attached data structures.
+	 * This is called from dm-raid
+	 */
+	__md_stop(mddev);
+	bitmap_destroy(mddev);
+	if (mddev->bio_set)
+		bioset_free(mddev->bio_set);
+}
+
+EXPORT_SYMBOL_GPL(md_stop);
+
+static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
+{
+	int err = 0;
+	int did_freeze = 0;
+
+	if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
+		did_freeze = 1;
+		set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+	}
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+	if (mddev->sync_thread)
+		/* Thread might be blocked waiting for metadata update
+		 * which will now never happen */
+		wake_up_process(mddev->sync_thread->tsk);
+
+	mddev_unlock(mddev);
+	wait_event(resync_wait, !test_bit(MD_RECOVERY_RUNNING,
+					  &mddev->recovery));
+	mddev_lock_nointr(mddev);
+
+	mutex_lock(&mddev->open_mutex);
+	if ((mddev->pers && atomic_read(&mddev->openers) > !!bdev) ||
+	    mddev->sync_thread ||
+	    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+	    (bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags))) {
+		printk("md: %s still in use.\n",mdname(mddev));
+		if (did_freeze) {
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			md_wakeup_thread(mddev->thread);
+		}
+		err = -EBUSY;
+		goto out;
+	}
+	if (mddev->pers) {
+		__md_stop_writes(mddev);
+
+		err  = -ENXIO;
+		if (mddev->ro==1)
+			goto out;
+		mddev->ro = 1;
+		set_disk_ro(mddev->gendisk, 1);
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+		err = 0;
+	}
+out:
+	mutex_unlock(&mddev->open_mutex);
+	return err;
+}
+
+/* mode:
+ *   0 - completely stop and dis-assemble array
+ *   2 - stop but do not disassemble array
+ */
+static int do_md_stop(struct mddev *mddev, int mode,
+		      struct block_device *bdev)
+{
+	struct gendisk *disk = mddev->gendisk;
+	struct md_rdev *rdev;
+	int did_freeze = 0;
+
+	if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
+		did_freeze = 1;
+		set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+	}
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+	if (mddev->sync_thread)
+		/* Thread might be blocked waiting for metadata update
+		 * which will now never happen */
+		wake_up_process(mddev->sync_thread->tsk);
+
+	mddev_unlock(mddev);
+	wait_event(resync_wait, (mddev->sync_thread == NULL &&
+				 !test_bit(MD_RECOVERY_RUNNING,
+					   &mddev->recovery)));
+	mddev_lock_nointr(mddev);
+
+	mutex_lock(&mddev->open_mutex);
+	if ((mddev->pers && atomic_read(&mddev->openers) > !!bdev) ||
+	    mddev->sysfs_active ||
+	    mddev->sync_thread ||
+	    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+	    (bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags))) {
+		printk("md: %s still in use.\n",mdname(mddev));
+		mutex_unlock(&mddev->open_mutex);
+		if (did_freeze) {
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			md_wakeup_thread(mddev->thread);
+		}
+		return -EBUSY;
+	}
+	if (mddev->pers) {
+		if (mddev->ro)
+			set_disk_ro(disk, 0);
+
+		__md_stop_writes(mddev);
+		__md_stop(mddev);
+		mddev->queue->merge_bvec_fn = NULL;
+		mddev->queue->backing_dev_info.congested_fn = NULL;
+
+		/* tell userspace to handle 'inactive' */
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+
+		rdev_for_each(rdev, mddev)
+			if (rdev->raid_disk >= 0)
+				sysfs_unlink_rdev(mddev, rdev);
+
+		set_capacity(disk, 0);
+		mutex_unlock(&mddev->open_mutex);
+		mddev->changed = 1;
+		revalidate_disk(disk);
+
+		if (mddev->ro)
+			mddev->ro = 0;
+	} else
+		mutex_unlock(&mddev->open_mutex);
+	/*
+	 * Free resources if final stop
+	 */
+	if (mode == 0) {
+		printk(KERN_INFO "md: %s stopped.\n", mdname(mddev));
+
+		bitmap_destroy(mddev);
+		if (mddev->bitmap_info.file) {
+			struct file *f = mddev->bitmap_info.file;
+			spin_lock(&mddev->lock);
+			mddev->bitmap_info.file = NULL;
+			spin_unlock(&mddev->lock);
+			fput(f);
+		}
+		mddev->bitmap_info.offset = 0;
+
+		export_array(mddev);
+
+		md_clean(mddev);
+		kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
+		if (mddev->hold_active == UNTIL_STOP)
+			mddev->hold_active = 0;
+	}
+	blk_integrity_unregister(disk);
+	md_new_event(mddev);
+	sysfs_notify_dirent_safe(mddev->sysfs_state);
+	return 0;
+}
+
+#ifndef MODULE
+static void autorun_array(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+	int err;
+
+	if (list_empty(&mddev->disks))
+		return;
+
+	printk(KERN_INFO "md: running: ");
+
+	rdev_for_each(rdev, mddev) {
+		char b[BDEVNAME_SIZE];
+		printk("<%s>", bdevname(rdev->bdev,b));
+	}
+	printk("\n");
+
+	err = do_md_run(mddev);
+	if (err) {
+		printk(KERN_WARNING "md: do_md_run() returned %d\n", err);
+		do_md_stop(mddev, 0, NULL);
+	}
+}
+
+/*
+ * lets try to run arrays based on all disks that have arrived
+ * until now. (those are in pending_raid_disks)
+ *
+ * the method: pick the first pending disk, collect all disks with
+ * the same UUID, remove all from the pending list and put them into
+ * the 'same_array' list. Then order this list based on superblock
+ * update time (freshest comes first), kick out 'old' disks and
+ * compare superblocks. If everything's fine then run it.
+ *
+ * If "unit" is allocated, then bump its reference count
+ */
+static void autorun_devices(int part)
+{
+	struct md_rdev *rdev0, *rdev, *tmp;
+	struct mddev *mddev;
+	char b[BDEVNAME_SIZE];
+
+	printk(KERN_INFO "md: autorun ...\n");
+	while (!list_empty(&pending_raid_disks)) {
+		int unit;
+		dev_t dev;
+		LIST_HEAD(candidates);
+		rdev0 = list_entry(pending_raid_disks.next,
+					 struct md_rdev, same_set);
+
+		printk(KERN_INFO "md: considering %s ...\n",
+			bdevname(rdev0->bdev,b));
+		INIT_LIST_HEAD(&candidates);
+		rdev_for_each_list(rdev, tmp, &pending_raid_disks)
+			if (super_90_load(rdev, rdev0, 0) >= 0) {
+				printk(KERN_INFO "md:  adding %s ...\n",
+					bdevname(rdev->bdev,b));
+				list_move(&rdev->same_set, &candidates);
+			}
+		/*
+		 * now we have a set of devices, with all of them having
+		 * mostly sane superblocks. It's time to allocate the
+		 * mddev.
+		 */
+		if (part) {
+			dev = MKDEV(mdp_major,
+				    rdev0->preferred_minor << MdpMinorShift);
+			unit = MINOR(dev) >> MdpMinorShift;
+		} else {
+			dev = MKDEV(MD_MAJOR, rdev0->preferred_minor);
+			unit = MINOR(dev);
+		}
+		if (rdev0->preferred_minor != unit) {
+			printk(KERN_INFO "md: unit number in %s is bad: %d\n",
+			       bdevname(rdev0->bdev, b), rdev0->preferred_minor);
+			break;
+		}
+
+		md_probe(dev, NULL, NULL);
+		mddev = mddev_find(dev);
+		if (!mddev || !mddev->gendisk) {
+			if (mddev)
+				mddev_put(mddev);
+			printk(KERN_ERR
+				"md: cannot allocate memory for md drive.\n");
+			break;
+		}
+		if (mddev_lock(mddev))
+			printk(KERN_WARNING "md: %s locked, cannot run\n",
+			       mdname(mddev));
+		else if (mddev->raid_disks || mddev->major_version
+			 || !list_empty(&mddev->disks)) {
+			printk(KERN_WARNING
+				"md: %s already running, cannot run %s\n",
+				mdname(mddev), bdevname(rdev0->bdev,b));
+			mddev_unlock(mddev);
+		} else {
+			printk(KERN_INFO "md: created %s\n", mdname(mddev));
+			mddev->persistent = 1;
+			rdev_for_each_list(rdev, tmp, &candidates) {
+				list_del_init(&rdev->same_set);
+				if (bind_rdev_to_array(rdev, mddev))
+					export_rdev(rdev);
+			}
+			autorun_array(mddev);
+			mddev_unlock(mddev);
+		}
+		/* on success, candidates will be empty, on error
+		 * it won't...
+		 */
+		rdev_for_each_list(rdev, tmp, &candidates) {
+			list_del_init(&rdev->same_set);
+			export_rdev(rdev);
+		}
+		mddev_put(mddev);
+	}
+	printk(KERN_INFO "md: ... autorun DONE.\n");
+}
+#endif /* !MODULE */
+
+static int get_version(void __user *arg)
+{
+	mdu_version_t ver;
+
+	ver.major = MD_MAJOR_VERSION;
+	ver.minor = MD_MINOR_VERSION;
+	ver.patchlevel = MD_PATCHLEVEL_VERSION;
+
+	if (copy_to_user(arg, &ver, sizeof(ver)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int get_array_info(struct mddev *mddev, void __user *arg)
+{
+	mdu_array_info_t info;
+	int nr,working,insync,failed,spare;
+	struct md_rdev *rdev;
+
+	nr = working = insync = failed = spare = 0;
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev) {
+		nr++;
+		if (test_bit(Faulty, &rdev->flags))
+			failed++;
+		else {
+			working++;
+			if (test_bit(In_sync, &rdev->flags))
+				insync++;
+			else
+				spare++;
+		}
+	}
+	rcu_read_unlock();
+
+	info.major_version = mddev->major_version;
+	info.minor_version = mddev->minor_version;
+	info.patch_version = MD_PATCHLEVEL_VERSION;
+	info.ctime         = mddev->ctime;
+	info.level         = mddev->level;
+	info.size          = mddev->dev_sectors / 2;
+	if (info.size != mddev->dev_sectors / 2) /* overflow */
+		info.size = -1;
+	info.nr_disks      = nr;
+	info.raid_disks    = mddev->raid_disks;
+	info.md_minor      = mddev->md_minor;
+	info.not_persistent= !mddev->persistent;
+
+	info.utime         = mddev->utime;
+	info.state         = 0;
+	if (mddev->in_sync)
+		info.state = (1<<MD_SB_CLEAN);
+	if (mddev->bitmap && mddev->bitmap_info.offset)
+		info.state |= (1<<MD_SB_BITMAP_PRESENT);
+	if (mddev_is_clustered(mddev))
+		info.state |= (1<<MD_SB_CLUSTERED);
+	info.active_disks  = insync;
+	info.working_disks = working;
+	info.failed_disks  = failed;
+	info.spare_disks   = spare;
+
+	info.layout        = mddev->layout;
+	info.chunk_size    = mddev->chunk_sectors << 9;
+
+	if (copy_to_user(arg, &info, sizeof(info)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int get_bitmap_file(struct mddev *mddev, void __user * arg)
+{
+	mdu_bitmap_file_t *file = NULL; /* too big for stack allocation */
+	char *ptr;
+	int err;
+
+	file = kmalloc(sizeof(*file), GFP_NOIO);
+	if (!file)
+		return -ENOMEM;
+
+	err = 0;
+	spin_lock(&mddev->lock);
+	/* bitmap disabled, zero the first byte and copy out */
+	if (!mddev->bitmap_info.file)
+		file->pathname[0] = '\0';
+	else if ((ptr = d_path(&mddev->bitmap_info.file->f_path,
+			       file->pathname, sizeof(file->pathname))),
+		 IS_ERR(ptr))
+		err = PTR_ERR(ptr);
+	else
+		memmove(file->pathname, ptr,
+			sizeof(file->pathname)-(ptr-file->pathname));
+	spin_unlock(&mddev->lock);
+
+	if (err == 0 &&
+	    copy_to_user(arg, file, sizeof(*file)))
+		err = -EFAULT;
+
+	kfree(file);
+	return err;
+}
+
+static int get_disk_info(struct mddev *mddev, void __user * arg)
+{
+	mdu_disk_info_t info;
+	struct md_rdev *rdev;
+
+	if (copy_from_user(&info, arg, sizeof(info)))
+		return -EFAULT;
+
+	rcu_read_lock();
+	rdev = md_find_rdev_nr_rcu(mddev, info.number);
+	if (rdev) {
+		info.major = MAJOR(rdev->bdev->bd_dev);
+		info.minor = MINOR(rdev->bdev->bd_dev);
+		info.raid_disk = rdev->raid_disk;
+		info.state = 0;
+		if (test_bit(Faulty, &rdev->flags))
+			info.state |= (1<<MD_DISK_FAULTY);
+		else if (test_bit(In_sync, &rdev->flags)) {
+			info.state |= (1<<MD_DISK_ACTIVE);
+			info.state |= (1<<MD_DISK_SYNC);
+		}
+		if (test_bit(WriteMostly, &rdev->flags))
+			info.state |= (1<<MD_DISK_WRITEMOSTLY);
+	} else {
+		info.major = info.minor = 0;
+		info.raid_disk = -1;
+		info.state = (1<<MD_DISK_REMOVED);
+	}
+	rcu_read_unlock();
+
+	if (copy_to_user(arg, &info, sizeof(info)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
+{
+	char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
+	struct md_rdev *rdev;
+	dev_t dev = MKDEV(info->major,info->minor);
+
+	if (mddev_is_clustered(mddev) &&
+		!(info->state & ((1 << MD_DISK_CLUSTER_ADD) | (1 << MD_DISK_CANDIDATE)))) {
+		pr_err("%s: Cannot add to clustered mddev.\n",
+			       mdname(mddev));
+		return -EINVAL;
+	}
+
+	if (info->major != MAJOR(dev) || info->minor != MINOR(dev))
+		return -EOVERFLOW;
+
+	if (!mddev->raid_disks) {
+		int err;
+		/* expecting a device which has a superblock */
+		rdev = md_import_device(dev, mddev->major_version, mddev->minor_version);
+		if (IS_ERR(rdev)) {
+			printk(KERN_WARNING
+				"md: md_import_device returned %ld\n",
+				PTR_ERR(rdev));
+			return PTR_ERR(rdev);
+		}
+		if (!list_empty(&mddev->disks)) {
+			struct md_rdev *rdev0
+				= list_entry(mddev->disks.next,
+					     struct md_rdev, same_set);
+			err = super_types[mddev->major_version]
+				.load_super(rdev, rdev0, mddev->minor_version);
+			if (err < 0) {
+				printk(KERN_WARNING
+					"md: %s has different UUID to %s\n",
+					bdevname(rdev->bdev,b),
+					bdevname(rdev0->bdev,b2));
+				export_rdev(rdev);
+				return -EINVAL;
+			}
+		}
+		err = bind_rdev_to_array(rdev, mddev);
+		if (err)
+			export_rdev(rdev);
+		return err;
+	}
+
+	/*
+	 * add_new_disk can be used once the array is assembled
+	 * to add "hot spares".  They must already have a superblock
+	 * written
+	 */
+	if (mddev->pers) {
+		int err;
+		if (!mddev->pers->hot_add_disk) {
+			printk(KERN_WARNING
+				"%s: personality does not support diskops!\n",
+			       mdname(mddev));
+			return -EINVAL;
+		}
+		if (mddev->persistent)
+			rdev = md_import_device(dev, mddev->major_version,
+						mddev->minor_version);
+		else
+			rdev = md_import_device(dev, -1, -1);
+		if (IS_ERR(rdev)) {
+			printk(KERN_WARNING
+				"md: md_import_device returned %ld\n",
+				PTR_ERR(rdev));
+			return PTR_ERR(rdev);
+		}
+		/* set saved_raid_disk if appropriate */
+		if (!mddev->persistent) {
+			if (info->state & (1<<MD_DISK_SYNC)  &&
+			    info->raid_disk < mddev->raid_disks) {
+				rdev->raid_disk = info->raid_disk;
+				set_bit(In_sync, &rdev->flags);
+				clear_bit(Bitmap_sync, &rdev->flags);
+			} else
+				rdev->raid_disk = -1;
+			rdev->saved_raid_disk = rdev->raid_disk;
+		} else
+			super_types[mddev->major_version].
+				validate_super(mddev, rdev);
+		if ((info->state & (1<<MD_DISK_SYNC)) &&
+		     rdev->raid_disk != info->raid_disk) {
+			/* This was a hot-add request, but events doesn't
+			 * match, so reject it.
+			 */
+			export_rdev(rdev);
+			return -EINVAL;
+		}
+
+		clear_bit(In_sync, &rdev->flags); /* just to be sure */
+		if (info->state & (1<<MD_DISK_WRITEMOSTLY))
+			set_bit(WriteMostly, &rdev->flags);
+		else
+			clear_bit(WriteMostly, &rdev->flags);
+
+		/*
+		 * check whether the device shows up in other nodes
+		 */
+		if (mddev_is_clustered(mddev)) {
+			if (info->state & (1 << MD_DISK_CANDIDATE)) {
+				/* Through --cluster-confirm */
+				set_bit(Candidate, &rdev->flags);
+				err = md_cluster_ops->new_disk_ack(mddev, true);
+				if (err) {
+					export_rdev(rdev);
+					return err;
+				}
+			} else if (info->state & (1 << MD_DISK_CLUSTER_ADD)) {
+				/* --add initiated by this node */
+				err = md_cluster_ops->add_new_disk_start(mddev, rdev);
+				if (err) {
+					md_cluster_ops->add_new_disk_finish(mddev);
+					export_rdev(rdev);
+					return err;
+				}
+			}
+		}
+
+		rdev->raid_disk = -1;
+		err = bind_rdev_to_array(rdev, mddev);
+		if (err)
+			export_rdev(rdev);
+		else
+			err = add_bound_rdev(rdev);
+		if (mddev_is_clustered(mddev) &&
+				(info->state & (1 << MD_DISK_CLUSTER_ADD)))
+			md_cluster_ops->add_new_disk_finish(mddev);
+		return err;
+	}
+
+	/* otherwise, add_new_disk is only allowed
+	 * for major_version==0 superblocks
+	 */
+	if (mddev->major_version != 0) {
+		printk(KERN_WARNING "%s: ADD_NEW_DISK not supported\n",
+		       mdname(mddev));
+		return -EINVAL;
+	}
+
+	if (!(info->state & (1<<MD_DISK_FAULTY))) {
+		int err;
+		rdev = md_import_device(dev, -1, 0);
+		if (IS_ERR(rdev)) {
+			printk(KERN_WARNING
+				"md: error, md_import_device() returned %ld\n",
+				PTR_ERR(rdev));
+			return PTR_ERR(rdev);
+		}
+		rdev->desc_nr = info->number;
+		if (info->raid_disk < mddev->raid_disks)
+			rdev->raid_disk = info->raid_disk;
+		else
+			rdev->raid_disk = -1;
+
+		if (rdev->raid_disk < mddev->raid_disks)
+			if (info->state & (1<<MD_DISK_SYNC))
+				set_bit(In_sync, &rdev->flags);
+
+		if (info->state & (1<<MD_DISK_WRITEMOSTLY))
+			set_bit(WriteMostly, &rdev->flags);
+
+		if (!mddev->persistent) {
+			printk(KERN_INFO "md: nonpersistent superblock ...\n");
+			rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;
+		} else
+			rdev->sb_start = calc_dev_sboffset(rdev);
+		rdev->sectors = rdev->sb_start;
+
+		err = bind_rdev_to_array(rdev, mddev);
+		if (err) {
+			export_rdev(rdev);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int hot_remove_disk(struct mddev *mddev, dev_t dev)
+{
+	char b[BDEVNAME_SIZE];
+	struct md_rdev *rdev;
+
+	rdev = find_rdev(mddev, dev);
+	if (!rdev)
+		return -ENXIO;
+
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_start(mddev);
+
+	clear_bit(Blocked, &rdev->flags);
+	remove_and_add_spares(mddev, rdev);
+
+	if (rdev->raid_disk >= 0)
+		goto busy;
+
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->remove_disk(mddev, rdev);
+
+	md_kick_rdev_from_array(rdev);
+	md_update_sb(mddev, 1);
+	md_new_event(mddev);
+
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_finish(mddev);
+
+	return 0;
+busy:
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_cancel(mddev);
+	printk(KERN_WARNING "md: cannot remove active disk %s from %s ...\n",
+		bdevname(rdev->bdev,b), mdname(mddev));
+	return -EBUSY;
+}
+
+static int hot_add_disk(struct mddev *mddev, dev_t dev)
+{
+	char b[BDEVNAME_SIZE];
+	int err;
+	struct md_rdev *rdev;
+
+	if (!mddev->pers)
+		return -ENODEV;
+
+	if (mddev->major_version != 0) {
+		printk(KERN_WARNING "%s: HOT_ADD may only be used with"
+			" version-0 superblocks.\n",
+			mdname(mddev));
+		return -EINVAL;
+	}
+	if (!mddev->pers->hot_add_disk) {
+		printk(KERN_WARNING
+			"%s: personality does not support diskops!\n",
+			mdname(mddev));
+		return -EINVAL;
+	}
+
+	rdev = md_import_device(dev, -1, 0);
+	if (IS_ERR(rdev)) {
+		printk(KERN_WARNING
+			"md: error, md_import_device() returned %ld\n",
+			PTR_ERR(rdev));
+		return -EINVAL;
+	}
+
+	if (mddev->persistent)
+		rdev->sb_start = calc_dev_sboffset(rdev);
+	else
+		rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;
+
+	rdev->sectors = rdev->sb_start;
+
+	if (test_bit(Faulty, &rdev->flags)) {
+		printk(KERN_WARNING
+			"md: can not hot-add faulty %s disk to %s!\n",
+			bdevname(rdev->bdev,b), mdname(mddev));
+		err = -EINVAL;
+		goto abort_export;
+	}
+
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_start(mddev);
+	clear_bit(In_sync, &rdev->flags);
+	rdev->desc_nr = -1;
+	rdev->saved_raid_disk = -1;
+	err = bind_rdev_to_array(rdev, mddev);
+	if (err)
+		goto abort_clustered;
+
+	/*
+	 * The rest should better be atomic, we can have disk failures
+	 * noticed in interrupt contexts ...
+	 */
+
+	rdev->raid_disk = -1;
+
+	md_update_sb(mddev, 1);
+
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_finish(mddev);
+	/*
+	 * Kick recovery, maybe this spare has to be added to the
+	 * array immediately.
+	 */
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	md_new_event(mddev);
+	return 0;
+
+abort_clustered:
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_cancel(mddev);
+abort_export:
+	export_rdev(rdev);
+	return err;
+}
+
+static int set_bitmap_file(struct mddev *mddev, int fd)
+{
+	int err = 0;
+
+	if (mddev->pers) {
+		if (!mddev->pers->quiesce || !mddev->thread)
+			return -EBUSY;
+		if (mddev->recovery || mddev->sync_thread)
+			return -EBUSY;
+		/* we should be able to change the bitmap.. */
+	}
+
+	if (fd >= 0) {
+		struct inode *inode;
+		struct file *f;
+
+		if (mddev->bitmap || mddev->bitmap_info.file)
+			return -EEXIST; /* cannot add when bitmap is present */
+		f = fget(fd);
+
+		if (f == NULL) {
+			printk(KERN_ERR "%s: error: failed to get bitmap file\n",
+			       mdname(mddev));
+			return -EBADF;
+		}
+
+		inode = f->f_mapping->host;
+		if (!S_ISREG(inode->i_mode)) {
+			printk(KERN_ERR "%s: error: bitmap file must be a regular file\n",
+			       mdname(mddev));
+			err = -EBADF;
+		} else if (!(f->f_mode & FMODE_WRITE)) {
+			printk(KERN_ERR "%s: error: bitmap file must open for write\n",
+			       mdname(mddev));
+			err = -EBADF;
+		} else if (atomic_read(&inode->i_writecount) != 1) {
+			printk(KERN_ERR "%s: error: bitmap file is already in use\n",
+			       mdname(mddev));
+			err = -EBUSY;
+		}
+		if (err) {
+			fput(f);
+			return err;
+		}
+		mddev->bitmap_info.file = f;
+		mddev->bitmap_info.offset = 0; /* file overrides offset */
+	} else if (mddev->bitmap == NULL)
+		return -ENOENT; /* cannot remove what isn't there */
+	err = 0;
+	if (mddev->pers) {
+		mddev->pers->quiesce(mddev, 1);
+		if (fd >= 0) {
+			struct bitmap *bitmap;
+
+			bitmap = bitmap_create(mddev, -1);
+			if (!IS_ERR(bitmap)) {
+				mddev->bitmap = bitmap;
+				err = bitmap_load(mddev);
+			} else
+				err = PTR_ERR(bitmap);
+		}
+		if (fd < 0 || err) {
+			bitmap_destroy(mddev);
+			fd = -1; /* make sure to put the file */
+		}
+		mddev->pers->quiesce(mddev, 0);
+	}
+	if (fd < 0) {
+		struct file *f = mddev->bitmap_info.file;
+		if (f) {
+			spin_lock(&mddev->lock);
+			mddev->bitmap_info.file = NULL;
+			spin_unlock(&mddev->lock);
+			fput(f);
+		}
+	}
+
+	return err;
+}
+
+/*
+ * set_array_info is used two different ways
+ * The original usage is when creating a new array.
+ * In this usage, raid_disks is > 0 and it together with
+ *  level, size, not_persistent,layout,chunksize determine the
+ *  shape of the array.
+ *  This will always create an array with a type-0.90.0 superblock.
+ * The newer usage is when assembling an array.
+ *  In this case raid_disks will be 0, and the major_version field is
+ *  use to determine which style super-blocks are to be found on the devices.
+ *  The minor and patch _version numbers are also kept incase the
+ *  super_block handler wishes to interpret them.
+ */
+static int set_array_info(struct mddev *mddev, mdu_array_info_t *info)
+{
+
+	if (info->raid_disks == 0) {
+		/* just setting version number for superblock loading */
+		if (info->major_version < 0 ||
+		    info->major_version >= ARRAY_SIZE(super_types) ||
+		    super_types[info->major_version].name == NULL) {
+			/* maybe try to auto-load a module? */
+			printk(KERN_INFO
+				"md: superblock version %d not known\n",
+				info->major_version);
+			return -EINVAL;
+		}
+		mddev->major_version = info->major_version;
+		mddev->minor_version = info->minor_version;
+		mddev->patch_version = info->patch_version;
+		mddev->persistent = !info->not_persistent;
+		/* ensure mddev_put doesn't delete this now that there
+		 * is some minimal configuration.
+		 */
+		mddev->ctime         = get_seconds();
+		return 0;
+	}
+	mddev->major_version = MD_MAJOR_VERSION;
+	mddev->minor_version = MD_MINOR_VERSION;
+	mddev->patch_version = MD_PATCHLEVEL_VERSION;
+	mddev->ctime         = get_seconds();
+
+	mddev->level         = info->level;
+	mddev->clevel[0]     = 0;
+	mddev->dev_sectors   = 2 * (sector_t)info->size;
+	mddev->raid_disks    = info->raid_disks;
+	/* don't set md_minor, it is determined by which /dev/md* was
+	 * openned
+	 */
+	if (info->state & (1<<MD_SB_CLEAN))
+		mddev->recovery_cp = MaxSector;
+	else
+		mddev->recovery_cp = 0;
+	mddev->persistent    = ! info->not_persistent;
+	mddev->external	     = 0;
+
+	mddev->layout        = info->layout;
+	mddev->chunk_sectors = info->chunk_size >> 9;
+
+	mddev->max_disks     = MD_SB_DISKS;
+
+	if (mddev->persistent)
+		mddev->flags         = 0;
+	set_bit(MD_CHANGE_DEVS, &mddev->flags);
+
+	mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
+	mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
+	mddev->bitmap_info.offset = 0;
+
+	mddev->reshape_position = MaxSector;
+
+	/*
+	 * Generate a 128 bit UUID
+	 */
+	get_random_bytes(mddev->uuid, 16);
+
+	mddev->new_level = mddev->level;
+	mddev->new_chunk_sectors = mddev->chunk_sectors;
+	mddev->new_layout = mddev->layout;
+	mddev->delta_disks = 0;
+	mddev->reshape_backwards = 0;
+
+	return 0;
+}
+
+void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors)
+{
+	WARN(!mddev_is_locked(mddev), "%s: unlocked mddev!\n", __func__);
+
+	if (mddev->external_size)
+		return;
+
+	mddev->array_sectors = array_sectors;
+}
+EXPORT_SYMBOL(md_set_array_sectors);
+
+static int update_size(struct mddev *mddev, sector_t num_sectors)
+{
+	struct md_rdev *rdev;
+	int rv;
+	int fit = (num_sectors == 0);
+
+	if (mddev->pers->resize == NULL)
+		return -EINVAL;
+	/* The "num_sectors" is the number of sectors of each device that
+	 * is used.  This can only make sense for arrays with redundancy.
+	 * linear and raid0 always use whatever space is available. We can only
+	 * consider changing this number if no resync or reconstruction is
+	 * happening, and if the new size is acceptable. It must fit before the
+	 * sb_start or, if that is <data_offset, it must fit before the size
+	 * of each device.  If num_sectors is zero, we find the largest size
+	 * that fits.
+	 */
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+	    mddev->sync_thread)
+		return -EBUSY;
+	if (mddev->ro)
+		return -EROFS;
+
+	rdev_for_each(rdev, mddev) {
+		sector_t avail = rdev->sectors;
+
+		if (fit && (num_sectors == 0 || num_sectors > avail))
+			num_sectors = avail;
+		if (avail < num_sectors)
+			return -ENOSPC;
+	}
+	rv = mddev->pers->resize(mddev, num_sectors);
+	if (!rv)
+		revalidate_disk(mddev->gendisk);
+	return rv;
+}
+
+static int update_raid_disks(struct mddev *mddev, int raid_disks)
+{
+	int rv;
+	struct md_rdev *rdev;
+	/* change the number of raid disks */
+	if (mddev->pers->check_reshape == NULL)
+		return -EINVAL;
+	if (mddev->ro)
+		return -EROFS;
+	if (raid_disks <= 0 ||
+	    (mddev->max_disks && raid_disks >= mddev->max_disks))
+		return -EINVAL;
+	if (mddev->sync_thread ||
+	    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+	    mddev->reshape_position != MaxSector)
+		return -EBUSY;
+
+	rdev_for_each(rdev, mddev) {
+		if (mddev->raid_disks < raid_disks &&
+		    rdev->data_offset < rdev->new_data_offset)
+			return -EINVAL;
+		if (mddev->raid_disks > raid_disks &&
+		    rdev->data_offset > rdev->new_data_offset)
+			return -EINVAL;
+	}
+
+	mddev->delta_disks = raid_disks - mddev->raid_disks;
+	if (mddev->delta_disks < 0)
+		mddev->reshape_backwards = 1;
+	else if (mddev->delta_disks > 0)
+		mddev->reshape_backwards = 0;
+
+	rv = mddev->pers->check_reshape(mddev);
+	if (rv < 0) {
+		mddev->delta_disks = 0;
+		mddev->reshape_backwards = 0;
+	}
+	return rv;
+}
+
+/*
+ * update_array_info is used to change the configuration of an
+ * on-line array.
+ * The version, ctime,level,size,raid_disks,not_persistent, layout,chunk_size
+ * fields in the info are checked against the array.
+ * Any differences that cannot be handled will cause an error.
+ * Normally, only one change can be managed at a time.
+ */
+static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
+{
+	int rv = 0;
+	int cnt = 0;
+	int state = 0;
+
+	/* calculate expected state,ignoring low bits */
+	if (mddev->bitmap && mddev->bitmap_info.offset)
+		state |= (1 << MD_SB_BITMAP_PRESENT);
+
+	if (mddev->major_version != info->major_version ||
+	    mddev->minor_version != info->minor_version ||
+/*	    mddev->patch_version != info->patch_version || */
+	    mddev->ctime         != info->ctime         ||
+	    mddev->level         != info->level         ||
+/*	    mddev->layout        != info->layout        || */
+	    mddev->persistent	 != !info->not_persistent ||
+	    mddev->chunk_sectors != info->chunk_size >> 9 ||
+	    /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT to change */
+	    ((state^info->state) & 0xfffffe00)
+		)
+		return -EINVAL;
+	/* Check there is only one change */
+	if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
+		cnt++;
+	if (mddev->raid_disks != info->raid_disks)
+		cnt++;
+	if (mddev->layout != info->layout)
+		cnt++;
+	if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT))
+		cnt++;
+	if (cnt == 0)
+		return 0;
+	if (cnt > 1)
+		return -EINVAL;
+
+	if (mddev->layout != info->layout) {
+		/* Change layout
+		 * we don't need to do anything at the md level, the
+		 * personality will take care of it all.
+		 */
+		if (mddev->pers->check_reshape == NULL)
+			return -EINVAL;
+		else {
+			mddev->new_layout = info->layout;
+			rv = mddev->pers->check_reshape(mddev);
+			if (rv)
+				mddev->new_layout = mddev->layout;
+			return rv;
+		}
+	}
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_start(mddev);
+	if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
+		rv = update_size(mddev, (sector_t)info->size * 2);
+
+	if (mddev->raid_disks    != info->raid_disks)
+		rv = update_raid_disks(mddev, info->raid_disks);
+
+	if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) {
+		if (mddev->pers->quiesce == NULL || mddev->thread == NULL) {
+			rv = -EINVAL;
+			goto err;
+		}
+		if (mddev->recovery || mddev->sync_thread) {
+			rv = -EBUSY;
+			goto err;
+		}
+		if (info->state & (1<<MD_SB_BITMAP_PRESENT)) {
+			struct bitmap *bitmap;
+			/* add the bitmap */
+			if (mddev->bitmap) {
+				rv = -EEXIST;
+				goto err;
+			}
+			if (mddev->bitmap_info.default_offset == 0) {
+				rv = -EINVAL;
+				goto err;
+			}
+			mddev->bitmap_info.offset =
+				mddev->bitmap_info.default_offset;
+			mddev->bitmap_info.space =
+				mddev->bitmap_info.default_space;
+			mddev->pers->quiesce(mddev, 1);
+			bitmap = bitmap_create(mddev, -1);
+			if (!IS_ERR(bitmap)) {
+				mddev->bitmap = bitmap;
+				rv = bitmap_load(mddev);
+			} else
+				rv = PTR_ERR(bitmap);
+			if (rv)
+				bitmap_destroy(mddev);
+			mddev->pers->quiesce(mddev, 0);
+		} else {
+			/* remove the bitmap */
+			if (!mddev->bitmap) {
+				rv = -ENOENT;
+				goto err;
+			}
+			if (mddev->bitmap->storage.file) {
+				rv = -EINVAL;
+				goto err;
+			}
+			mddev->pers->quiesce(mddev, 1);
+			bitmap_destroy(mddev);
+			mddev->pers->quiesce(mddev, 0);
+			mddev->bitmap_info.offset = 0;
+		}
+	}
+	md_update_sb(mddev, 1);
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_finish(mddev);
+	return rv;
+err:
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_cancel(mddev);
+	return rv;
+}
+
+static int set_disk_faulty(struct mddev *mddev, dev_t dev)
+{
+	struct md_rdev *rdev;
+	int err = 0;
+
+	if (mddev->pers == NULL)
+		return -ENODEV;
+
+	rcu_read_lock();
+	rdev = find_rdev_rcu(mddev, dev);
+	if (!rdev)
+		err =  -ENODEV;
+	else {
+		md_error(mddev, rdev);
+		if (!test_bit(Faulty, &rdev->flags))
+			err = -EBUSY;
+	}
+	rcu_read_unlock();
+	return err;
+}
+
+/*
+ * We have a problem here : there is no easy way to give a CHS
+ * virtual geometry. We currently pretend that we have a 2 heads
+ * 4 sectors (with a BIG number of cylinders...). This drives
+ * dosfs just mad... ;-)
+ */
+static int md_getgeo(struct block_device *bdev, struct hd_geometry *geo)
+{
+	struct mddev *mddev = bdev->bd_disk->private_data;
+
+	geo->heads = 2;
+	geo->sectors = 4;
+	geo->cylinders = mddev->array_sectors / 8;
+	return 0;
+}
+
+static inline bool md_ioctl_valid(unsigned int cmd)
+{
+	switch (cmd) {
+	case ADD_NEW_DISK:
+	case BLKROSET:
+	case GET_ARRAY_INFO:
+	case GET_BITMAP_FILE:
+	case GET_DISK_INFO:
+	case HOT_ADD_DISK:
+	case HOT_REMOVE_DISK:
+	case RAID_AUTORUN:
+	case RAID_VERSION:
+	case RESTART_ARRAY_RW:
+	case RUN_ARRAY:
+	case SET_ARRAY_INFO:
+	case SET_BITMAP_FILE:
+	case SET_DISK_FAULTY:
+	case STOP_ARRAY:
+	case STOP_ARRAY_RO:
+	case CLUSTERED_DISK_NACK:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static int md_ioctl(struct block_device *bdev, fmode_t mode,
+			unsigned int cmd, unsigned long arg)
+{
+	int err = 0;
+	void __user *argp = (void __user *)arg;
+	struct mddev *mddev = NULL;
+	int ro;
+
+	if (!md_ioctl_valid(cmd))
+		return -ENOTTY;
+
+	switch (cmd) {
+	case RAID_VERSION:
+	case GET_ARRAY_INFO:
+	case GET_DISK_INFO:
+		break;
+	default:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EACCES;
+	}
+
+	/*
+	 * Commands dealing with the RAID driver but not any
+	 * particular array:
+	 */
+	switch (cmd) {
+	case RAID_VERSION:
+		err = get_version(argp);
+		goto out;
+
+#ifndef MODULE
+	case RAID_AUTORUN:
+		err = 0;
+		autostart_arrays(arg);
+		goto out;
+#endif
+	default:;
+	}
+
+	/*
+	 * Commands creating/starting a new array:
+	 */
+
+	mddev = bdev->bd_disk->private_data;
+
+	if (!mddev) {
+		BUG();
+		goto out;
+	}
+
+	/* Some actions do not requires the mutex */
+	switch (cmd) {
+	case GET_ARRAY_INFO:
+		if (!mddev->raid_disks && !mddev->external)
+			err = -ENODEV;
+		else
+			err = get_array_info(mddev, argp);
+		goto out;
+
+	case GET_DISK_INFO:
+		if (!mddev->raid_disks && !mddev->external)
+			err = -ENODEV;
+		else
+			err = get_disk_info(mddev, argp);
+		goto out;
+
+	case SET_DISK_FAULTY:
+		err = set_disk_faulty(mddev, new_decode_dev(arg));
+		goto out;
+
+	case GET_BITMAP_FILE:
+		err = get_bitmap_file(mddev, argp);
+		goto out;
+
+	}
+
+	if (cmd == ADD_NEW_DISK)
+		/* need to ensure md_delayed_delete() has completed */
+		flush_workqueue(md_misc_wq);
+
+	if (cmd == HOT_REMOVE_DISK)
+		/* need to ensure recovery thread has run */
+		wait_event_interruptible_timeout(mddev->sb_wait,
+						 !test_bit(MD_RECOVERY_NEEDED,
+							   &mddev->flags),
+						 msecs_to_jiffies(5000));
+	if (cmd == STOP_ARRAY || cmd == STOP_ARRAY_RO) {
+		/* Need to flush page cache, and ensure no-one else opens
+		 * and writes
+		 */
+		mutex_lock(&mddev->open_mutex);
+		if (mddev->pers && atomic_read(&mddev->openers) > 1) {
+			mutex_unlock(&mddev->open_mutex);
+			err = -EBUSY;
+			goto out;
+		}
+		set_bit(MD_STILL_CLOSED, &mddev->flags);
+		mutex_unlock(&mddev->open_mutex);
+		sync_blockdev(bdev);
+	}
+	err = mddev_lock(mddev);
+	if (err) {
+		printk(KERN_INFO
+			"md: ioctl lock interrupted, reason %d, cmd %d\n",
+			err, cmd);
+		goto out;
+	}
+
+	if (cmd == SET_ARRAY_INFO) {
+		mdu_array_info_t info;
+		if (!arg)
+			memset(&info, 0, sizeof(info));
+		else if (copy_from_user(&info, argp, sizeof(info))) {
+			err = -EFAULT;
+			goto unlock;
+		}
+		if (mddev->pers) {
+			err = update_array_info(mddev, &info);
+			if (err) {
+				printk(KERN_WARNING "md: couldn't update"
+				       " array info. %d\n", err);
+				goto unlock;
+			}
+			goto unlock;
+		}
+		if (!list_empty(&mddev->disks)) {
+			printk(KERN_WARNING
+			       "md: array %s already has disks!\n",
+			       mdname(mddev));
+			err = -EBUSY;
+			goto unlock;
+		}
+		if (mddev->raid_disks) {
+			printk(KERN_WARNING
+			       "md: array %s already initialised!\n",
+			       mdname(mddev));
+			err = -EBUSY;
+			goto unlock;
+		}
+		err = set_array_info(mddev, &info);
+		if (err) {
+			printk(KERN_WARNING "md: couldn't set"
+			       " array info. %d\n", err);
+			goto unlock;
+		}
+		goto unlock;
+	}
+
+	/*
+	 * Commands querying/configuring an existing array:
+	 */
+	/* if we are not initialised yet, only ADD_NEW_DISK, STOP_ARRAY,
+	 * RUN_ARRAY, and GET_ and SET_BITMAP_FILE are allowed */
+	if ((!mddev->raid_disks && !mddev->external)
+	    && cmd != ADD_NEW_DISK && cmd != STOP_ARRAY
+	    && cmd != RUN_ARRAY && cmd != SET_BITMAP_FILE
+	    && cmd != GET_BITMAP_FILE) {
+		err = -ENODEV;
+		goto unlock;
+	}
+
+	/*
+	 * Commands even a read-only array can execute:
+	 */
+	switch (cmd) {
+	case RESTART_ARRAY_RW:
+		err = restart_array(mddev);
+		goto unlock;
+
+	case STOP_ARRAY:
+		err = do_md_stop(mddev, 0, bdev);
+		goto unlock;
+
+	case STOP_ARRAY_RO:
+		err = md_set_readonly(mddev, bdev);
+		goto unlock;
+
+	case HOT_REMOVE_DISK:
+		err = hot_remove_disk(mddev, new_decode_dev(arg));
+		goto unlock;
+
+	case ADD_NEW_DISK:
+		/* We can support ADD_NEW_DISK on read-only arrays
+		 * on if we are re-adding a preexisting device.
+		 * So require mddev->pers and MD_DISK_SYNC.
+		 */
+		if (mddev->pers) {
+			mdu_disk_info_t info;
+			if (copy_from_user(&info, argp, sizeof(info)))
+				err = -EFAULT;
+			else if (!(info.state & (1<<MD_DISK_SYNC)))
+				/* Need to clear read-only for this */
+				break;
+			else
+				err = add_new_disk(mddev, &info);
+			goto unlock;
+		}
+		break;
+
+	case BLKROSET:
+		if (get_user(ro, (int __user *)(arg))) {
+			err = -EFAULT;
+			goto unlock;
+		}
+		err = -EINVAL;
+
+		/* if the bdev is going readonly the value of mddev->ro
+		 * does not matter, no writes are coming
+		 */
+		if (ro)
+			goto unlock;
+
+		/* are we are already prepared for writes? */
+		if (mddev->ro != 1)
+			goto unlock;
+
+		/* transitioning to readauto need only happen for
+		 * arrays that call md_write_start
+		 */
+		if (mddev->pers) {
+			err = restart_array(mddev);
+			if (err == 0) {
+				mddev->ro = 2;
+				set_disk_ro(mddev->gendisk, 0);
+			}
+		}
+		goto unlock;
+	}
+
+	/*
+	 * The remaining ioctls are changing the state of the
+	 * superblock, so we do not allow them on read-only arrays.
+	 */
+	if (mddev->ro && mddev->pers) {
+		if (mddev->ro == 2) {
+			mddev->ro = 0;
+			sysfs_notify_dirent_safe(mddev->sysfs_state);
+			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			/* mddev_unlock will wake thread */
+			/* If a device failed while we were read-only, we
+			 * need to make sure the metadata is updated now.
+			 */
+			if (test_bit(MD_CHANGE_DEVS, &mddev->flags)) {
+				mddev_unlock(mddev);
+				wait_event(mddev->sb_wait,
+					   !test_bit(MD_CHANGE_DEVS, &mddev->flags) &&
+					   !test_bit(MD_CHANGE_PENDING, &mddev->flags));
+				mddev_lock_nointr(mddev);
+			}
+		} else {
+			err = -EROFS;
+			goto unlock;
+		}
+	}
+
+	switch (cmd) {
+	case ADD_NEW_DISK:
+	{
+		mdu_disk_info_t info;
+		if (copy_from_user(&info, argp, sizeof(info)))
+			err = -EFAULT;
+		else
+			err = add_new_disk(mddev, &info);
+		goto unlock;
+	}
+
+	case CLUSTERED_DISK_NACK:
+		if (mddev_is_clustered(mddev))
+			md_cluster_ops->new_disk_ack(mddev, false);
+		else
+			err = -EINVAL;
+		goto unlock;
+
+	case HOT_ADD_DISK:
+		err = hot_add_disk(mddev, new_decode_dev(arg));
+		goto unlock;
+
+	case RUN_ARRAY:
+		err = do_md_run(mddev);
+		goto unlock;
+
+	case SET_BITMAP_FILE:
+		err = set_bitmap_file(mddev, (int)arg);
+		goto unlock;
+
+	default:
+		err = -EINVAL;
+		goto unlock;
+	}
+
+unlock:
+	if (mddev->hold_active == UNTIL_IOCTL &&
+	    err != -EINVAL)
+		mddev->hold_active = 0;
+	mddev_unlock(mddev);
+out:
+	return err;
+}
+#ifdef CONFIG_COMPAT
+static int md_compat_ioctl(struct block_device *bdev, fmode_t mode,
+		    unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case HOT_REMOVE_DISK:
+	case HOT_ADD_DISK:
+	case SET_DISK_FAULTY:
+	case SET_BITMAP_FILE:
+		/* These take in integer arg, do not convert */
+		break;
+	default:
+		arg = (unsigned long)compat_ptr(arg);
+		break;
+	}
+
+	return md_ioctl(bdev, mode, cmd, arg);
+}
+#endif /* CONFIG_COMPAT */
+
+static int md_open(struct block_device *bdev, fmode_t mode)
+{
+	/*
+	 * Succeed if we can lock the mddev, which confirms that
+	 * it isn't being stopped right now.
+	 */
+	struct mddev *mddev = mddev_find(bdev->bd_dev);
+	int err;
+
+	if (!mddev)
+		return -ENODEV;
+
+	if (mddev->gendisk != bdev->bd_disk) {
+		/* we are racing with mddev_put which is discarding this
+		 * bd_disk.
+		 */
+		mddev_put(mddev);
+		/* Wait until bdev->bd_disk is definitely gone */
+		flush_workqueue(md_misc_wq);
+		/* Then retry the open from the top */
+		return -ERESTARTSYS;
+	}
+	BUG_ON(mddev != bdev->bd_disk->private_data);
+
+	if ((err = mutex_lock_interruptible(&mddev->open_mutex)))
+		goto out;
+
+	err = 0;
+	atomic_inc(&mddev->openers);
+	clear_bit(MD_STILL_CLOSED, &mddev->flags);
+	mutex_unlock(&mddev->open_mutex);
+
+	check_disk_change(bdev);
+ out:
+	return err;
+}
+
+static void md_release(struct gendisk *disk, fmode_t mode)
+{
+	struct mddev *mddev = disk->private_data;
+
+	BUG_ON(!mddev);
+	atomic_dec(&mddev->openers);
+	mddev_put(mddev);
+}
+
+static int md_media_changed(struct gendisk *disk)
+{
+	struct mddev *mddev = disk->private_data;
+
+	return mddev->changed;
+}
+
+static int md_revalidate(struct gendisk *disk)
+{
+	struct mddev *mddev = disk->private_data;
+
+	mddev->changed = 0;
+	return 0;
+}
+static const struct block_device_operations md_fops =
+{
+	.owner		= THIS_MODULE,
+	.open		= md_open,
+	.release	= md_release,
+	.ioctl		= md_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= md_compat_ioctl,
+#endif
+	.getgeo		= md_getgeo,
+	.media_changed  = md_media_changed,
+	.revalidate_disk= md_revalidate,
+};
+
+static int md_thread(void *arg)
+{
+	struct md_thread *thread = arg;
+
+	/*
+	 * md_thread is a 'system-thread', it's priority should be very
+	 * high. We avoid resource deadlocks individually in each
+	 * raid personality. (RAID5 does preallocation) We also use RR and
+	 * the very same RT priority as kswapd, thus we will never get
+	 * into a priority inversion deadlock.
+	 *
+	 * we definitely have to have equal or higher priority than
+	 * bdflush, otherwise bdflush will deadlock if there are too
+	 * many dirty RAID5 blocks.
+	 */
+
+	allow_signal(SIGKILL);
+	while (!kthread_should_stop()) {
+
+		/* We need to wait INTERRUPTIBLE so that
+		 * we don't add to the load-average.
+		 * That means we need to be sure no signals are
+		 * pending
+		 */
+		if (signal_pending(current))
+			flush_signals(current);
+
+		wait_event_interruptible_timeout
+			(thread->wqueue,
+			 test_bit(THREAD_WAKEUP, &thread->flags)
+			 || kthread_should_stop(),
+			 thread->timeout);
+
+		clear_bit(THREAD_WAKEUP, &thread->flags);
+		if (!kthread_should_stop())
+			thread->run(thread);
+	}
+
+	return 0;
+}
+
+void md_wakeup_thread(struct md_thread *thread)
+{
+	if (thread) {
+		pr_debug("md: waking up MD thread %s.\n", thread->tsk->comm);
+		set_bit(THREAD_WAKEUP, &thread->flags);
+		wake_up(&thread->wqueue);
+	}
+}
+EXPORT_SYMBOL(md_wakeup_thread);
+
+struct md_thread *md_register_thread(void (*run) (struct md_thread *),
+		struct mddev *mddev, const char *name)
+{
+	struct md_thread *thread;
+
+	thread = kzalloc(sizeof(struct md_thread), GFP_KERNEL);
+	if (!thread)
+		return NULL;
+
+	init_waitqueue_head(&thread->wqueue);
+
+	thread->run = run;
+	thread->mddev = mddev;
+	thread->timeout = MAX_SCHEDULE_TIMEOUT;
+	thread->tsk = kthread_run(md_thread, thread,
+				  "%s_%s",
+				  mdname(thread->mddev),
+				  name);
+	if (IS_ERR(thread->tsk)) {
+		kfree(thread);
+		return NULL;
+	}
+	return thread;
+}
+EXPORT_SYMBOL(md_register_thread);
+
+void md_unregister_thread(struct md_thread **threadp)
+{
+	struct md_thread *thread = *threadp;
+	if (!thread)
+		return;
+	pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
+	/* Locking ensures that mddev_unlock does not wake_up a
+	 * non-existent thread
+	 */
+	spin_lock(&pers_lock);
+	*threadp = NULL;
+	spin_unlock(&pers_lock);
+
+	kthread_stop(thread->tsk);
+	kfree(thread);
+}
+EXPORT_SYMBOL(md_unregister_thread);
+
+void md_error(struct mddev *mddev, struct md_rdev *rdev)
+{
+	if (!rdev || test_bit(Faulty, &rdev->flags))
+		return;
+
+	if (!mddev->pers || !mddev->pers->error_handler)
+		return;
+	mddev->pers->error_handler(mddev,rdev);
+	if (mddev->degraded)
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+	sysfs_notify_dirent_safe(rdev->sysfs_state);
+	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	if (mddev->event_work.func)
+		queue_work(md_misc_wq, &mddev->event_work);
+	md_new_event_inintr(mddev);
+}
+EXPORT_SYMBOL(md_error);
+
+/* seq_file implementation /proc/mdstat */
+
+static void status_unused(struct seq_file *seq)
+{
+	int i = 0;
+	struct md_rdev *rdev;
+
+	seq_printf(seq, "unused devices: ");
+
+	list_for_each_entry(rdev, &pending_raid_disks, same_set) {
+		char b[BDEVNAME_SIZE];
+		i++;
+		seq_printf(seq, "%s ",
+			      bdevname(rdev->bdev,b));
+	}
+	if (!i)
+		seq_printf(seq, "<none>");
+
+	seq_printf(seq, "\n");
+}
+
+static void status_resync(struct seq_file *seq, struct mddev *mddev)
+{
+	sector_t max_sectors, resync, res;
+	unsigned long dt, db;
+	sector_t rt;
+	int scale;
+	unsigned int per_milli;
+
+	if (mddev->curr_resync <= 3)
+		resync = 0;
+	else
+		resync = mddev->curr_resync
+			- atomic_read(&mddev->recovery_active);
+
+	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
+	    test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		max_sectors = mddev->resync_max_sectors;
+	else
+		max_sectors = mddev->dev_sectors;
+
+	WARN_ON(max_sectors == 0);
+	/* Pick 'scale' such that (resync>>scale)*1000 will fit
+	 * in a sector_t, and (max_sectors>>scale) will fit in a
+	 * u32, as those are the requirements for sector_div.
+	 * Thus 'scale' must be at least 10
+	 */
+	scale = 10;
+	if (sizeof(sector_t) > sizeof(unsigned long)) {
+		while ( max_sectors/2 > (1ULL<<(scale+32)))
+			scale++;
+	}
+	res = (resync>>scale)*1000;
+	sector_div(res, (u32)((max_sectors>>scale)+1));
+
+	per_milli = res;
+	{
+		int i, x = per_milli/50, y = 20-x;
+		seq_printf(seq, "[");
+		for (i = 0; i < x; i++)
+			seq_printf(seq, "=");
+		seq_printf(seq, ">");
+		for (i = 0; i < y; i++)
+			seq_printf(seq, ".");
+		seq_printf(seq, "] ");
+	}
+	seq_printf(seq, " %s =%3u.%u%% (%llu/%llu)",
+		   (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)?
+		    "reshape" :
+		    (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)?
+		     "check" :
+		     (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ?
+		      "resync" : "recovery"))),
+		   per_milli/10, per_milli % 10,
+		   (unsigned long long) resync/2,
+		   (unsigned long long) max_sectors/2);
+
+	/*
+	 * dt: time from mark until now
+	 * db: blocks written from mark until now
+	 * rt: remaining time
+	 *
+	 * rt is a sector_t, so could be 32bit or 64bit.
+	 * So we divide before multiply in case it is 32bit and close
+	 * to the limit.
+	 * We scale the divisor (db) by 32 to avoid losing precision
+	 * near the end of resync when the number of remaining sectors
+	 * is close to 'db'.
+	 * We then divide rt by 32 after multiplying by db to compensate.
+	 * The '+1' avoids division by zero if db is very small.
+	 */
+	dt = ((jiffies - mddev->resync_mark) / HZ);
+	if (!dt) dt++;
+	db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active))
+		- mddev->resync_mark_cnt;
+
+	rt = max_sectors - resync;    /* number of remaining sectors */
+	sector_div(rt, db/32+1);
+	rt *= dt;
+	rt >>= 5;
+
+	seq_printf(seq, " finish=%lu.%lumin", (unsigned long)rt / 60,
+		   ((unsigned long)rt % 60)/6);
+
+	seq_printf(seq, " speed=%ldK/sec", db/2/dt);
+}
+
+static void *md_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct list_head *tmp;
+	loff_t l = *pos;
+	struct mddev *mddev;
+
+	if (l >= 0x10000)
+		return NULL;
+	if (!l--)
+		/* header */
+		return (void*)1;
+
+	spin_lock(&all_mddevs_lock);
+	list_for_each(tmp,&all_mddevs)
+		if (!l--) {
+			mddev = list_entry(tmp, struct mddev, all_mddevs);
+			mddev_get(mddev);
+			spin_unlock(&all_mddevs_lock);
+			return mddev;
+		}
+	spin_unlock(&all_mddevs_lock);
+	if (!l--)
+		return (void*)2;/* tail */
+	return NULL;
+}
+
+static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct list_head *tmp;
+	struct mddev *next_mddev, *mddev = v;
+
+	++*pos;
+	if (v == (void*)2)
+		return NULL;
+
+	spin_lock(&all_mddevs_lock);
+	if (v == (void*)1)
+		tmp = all_mddevs.next;
+	else
+		tmp = mddev->all_mddevs.next;
+	if (tmp != &all_mddevs)
+		next_mddev = mddev_get(list_entry(tmp,struct mddev,all_mddevs));
+	else {
+		next_mddev = (void*)2;
+		*pos = 0x10000;
+	}
+	spin_unlock(&all_mddevs_lock);
+
+	if (v != (void*)1)
+		mddev_put(mddev);
+	return next_mddev;
+
+}
+
+static void md_seq_stop(struct seq_file *seq, void *v)
+{
+	struct mddev *mddev = v;
+
+	if (mddev && v != (void*)1 && v != (void*)2)
+		mddev_put(mddev);
+}
+
+static int md_seq_show(struct seq_file *seq, void *v)
+{
+	struct mddev *mddev = v;
+	sector_t sectors;
+	struct md_rdev *rdev;
+
+	if (v == (void*)1) {
+		struct md_personality *pers;
+		seq_printf(seq, "Personalities : ");
+		spin_lock(&pers_lock);
+		list_for_each_entry(pers, &pers_list, list)
+			seq_printf(seq, "[%s] ", pers->name);
+
+		spin_unlock(&pers_lock);
+		seq_printf(seq, "\n");
+		seq->poll_event = atomic_read(&md_event_count);
+		return 0;
+	}
+	if (v == (void*)2) {
+		status_unused(seq);
+		return 0;
+	}
+
+	spin_lock(&mddev->lock);
+	if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
+		seq_printf(seq, "%s : %sactive", mdname(mddev),
+						mddev->pers ? "" : "in");
+		if (mddev->pers) {
+			if (mddev->ro==1)
+				seq_printf(seq, " (read-only)");
+			if (mddev->ro==2)
+				seq_printf(seq, " (auto-read-only)");
+			seq_printf(seq, " %s", mddev->pers->name);
+		}
+
+		sectors = 0;
+		rcu_read_lock();
+		rdev_for_each_rcu(rdev, mddev) {
+			char b[BDEVNAME_SIZE];
+			seq_printf(seq, " %s[%d]",
+				bdevname(rdev->bdev,b), rdev->desc_nr);
+			if (test_bit(WriteMostly, &rdev->flags))
+				seq_printf(seq, "(W)");
+			if (test_bit(Faulty, &rdev->flags)) {
+				seq_printf(seq, "(F)");
+				continue;
+			}
+			if (rdev->raid_disk < 0)
+				seq_printf(seq, "(S)"); /* spare */
+			if (test_bit(Replacement, &rdev->flags))
+				seq_printf(seq, "(R)");
+			sectors += rdev->sectors;
+		}
+		rcu_read_unlock();
+
+		if (!list_empty(&mddev->disks)) {
+			if (mddev->pers)
+				seq_printf(seq, "\n      %llu blocks",
+					   (unsigned long long)
+					   mddev->array_sectors / 2);
+			else
+				seq_printf(seq, "\n      %llu blocks",
+					   (unsigned long long)sectors / 2);
+		}
+		if (mddev->persistent) {
+			if (mddev->major_version != 0 ||
+			    mddev->minor_version != 90) {
+				seq_printf(seq," super %d.%d",
+					   mddev->major_version,
+					   mddev->minor_version);
+			}
+		} else if (mddev->external)
+			seq_printf(seq, " super external:%s",
+				   mddev->metadata_type);
+		else
+			seq_printf(seq, " super non-persistent");
+
+		if (mddev->pers) {
+			mddev->pers->status(seq, mddev);
+			seq_printf(seq, "\n      ");
+			if (mddev->pers->sync_request) {
+				if (mddev->curr_resync > 2) {
+					status_resync(seq, mddev);
+					seq_printf(seq, "\n      ");
+				} else if (mddev->curr_resync >= 1)
+					seq_printf(seq, "\tresync=DELAYED\n      ");
+				else if (mddev->recovery_cp < MaxSector)
+					seq_printf(seq, "\tresync=PENDING\n      ");
+			}
+		} else
+			seq_printf(seq, "\n       ");
+
+		bitmap_status(seq, mddev->bitmap);
+
+		seq_printf(seq, "\n");
+	}
+	spin_unlock(&mddev->lock);
+
+	return 0;
+}
+
+static const struct seq_operations md_seq_ops = {
+	.start  = md_seq_start,
+	.next   = md_seq_next,
+	.stop   = md_seq_stop,
+	.show   = md_seq_show,
+};
+
+static int md_seq_open(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq;
+	int error;
+
+	error = seq_open(file, &md_seq_ops);
+	if (error)
+		return error;
+
+	seq = file->private_data;
+	seq->poll_event = atomic_read(&md_event_count);
+	return error;
+}
+
+static int md_unloading;
+static unsigned int mdstat_poll(struct file *filp, poll_table *wait)
+{
+	struct seq_file *seq = filp->private_data;
+	int mask;
+
+	if (md_unloading)
+		return POLLIN|POLLRDNORM|POLLERR|POLLPRI;
+	poll_wait(filp, &md_event_waiters, wait);
+
+	/* always allow read */
+	mask = POLLIN | POLLRDNORM;
+
+	if (seq->poll_event != atomic_read(&md_event_count))
+		mask |= POLLERR | POLLPRI;
+	return mask;
+}
+
+static const struct file_operations md_seq_fops = {
+	.owner		= THIS_MODULE,
+	.open           = md_seq_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release	= seq_release_private,
+	.poll		= mdstat_poll,
+};
+
+int register_md_personality(struct md_personality *p)
+{
+	printk(KERN_INFO "md: %s personality registered for level %d\n",
+						p->name, p->level);
+	spin_lock(&pers_lock);
+	list_add_tail(&p->list, &pers_list);
+	spin_unlock(&pers_lock);
+	return 0;
+}
+EXPORT_SYMBOL(register_md_personality);
+
+int unregister_md_personality(struct md_personality *p)
+{
+	printk(KERN_INFO "md: %s personality unregistered\n", p->name);
+	spin_lock(&pers_lock);
+	list_del_init(&p->list);
+	spin_unlock(&pers_lock);
+	return 0;
+}
+EXPORT_SYMBOL(unregister_md_personality);
+
+int register_md_cluster_operations(struct md_cluster_operations *ops, struct module *module)
+{
+	if (md_cluster_ops != NULL)
+		return -EALREADY;
+	spin_lock(&pers_lock);
+	md_cluster_ops = ops;
+	md_cluster_mod = module;
+	spin_unlock(&pers_lock);
+	return 0;
+}
+EXPORT_SYMBOL(register_md_cluster_operations);
+
+int unregister_md_cluster_operations(void)
+{
+	spin_lock(&pers_lock);
+	md_cluster_ops = NULL;
+	spin_unlock(&pers_lock);
+	return 0;
+}
+EXPORT_SYMBOL(unregister_md_cluster_operations);
+
+int md_setup_cluster(struct mddev *mddev, int nodes)
+{
+	int err;
+
+	err = request_module("md-cluster");
+	if (err) {
+		pr_err("md-cluster module not found.\n");
+		return -ENOENT;
+	}
+
+	spin_lock(&pers_lock);
+	if (!md_cluster_ops || !try_module_get(md_cluster_mod)) {
+		spin_unlock(&pers_lock);
+		return -ENOENT;
+	}
+	spin_unlock(&pers_lock);
+
+	return md_cluster_ops->join(mddev, nodes);
+}
+
+void md_cluster_stop(struct mddev *mddev)
+{
+	if (!md_cluster_ops)
+		return;
+	md_cluster_ops->leave(mddev);
+	module_put(md_cluster_mod);
+}
+
+static int is_mddev_idle(struct mddev *mddev, int init)
+{
+	struct md_rdev *rdev;
+	int idle;
+	int curr_events;
+
+	idle = 1;
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev) {
+		struct gendisk *disk = rdev->bdev->bd_contains->bd_disk;
+		curr_events = (int)part_stat_read(&disk->part0, sectors[0]) +
+			      (int)part_stat_read(&disk->part0, sectors[1]) -
+			      atomic_read(&disk->sync_io);
+		/* sync IO will cause sync_io to increase before the disk_stats
+		 * as sync_io is counted when a request starts, and
+		 * disk_stats is counted when it completes.
+		 * So resync activity will cause curr_events to be smaller than
+		 * when there was no such activity.
+		 * non-sync IO will cause disk_stat to increase without
+		 * increasing sync_io so curr_events will (eventually)
+		 * be larger than it was before.  Once it becomes
+		 * substantially larger, the test below will cause
+		 * the array to appear non-idle, and resync will slow
+		 * down.
+		 * If there is a lot of outstanding resync activity when
+		 * we set last_event to curr_events, then all that activity
+		 * completing might cause the array to appear non-idle
+		 * and resync will be slowed down even though there might
+		 * not have been non-resync activity.  This will only
+		 * happen once though.  'last_events' will soon reflect
+		 * the state where there is little or no outstanding
+		 * resync requests, and further resync activity will
+		 * always make curr_events less than last_events.
+		 *
+		 */
+		if (init || curr_events - rdev->last_events > 64) {
+			rdev->last_events = curr_events;
+			idle = 0;
+		}
+	}
+	rcu_read_unlock();
+	return idle;
+}
+
+void md_done_sync(struct mddev *mddev, int blocks, int ok)
+{
+	/* another "blocks" (512byte) blocks have been synced */
+	atomic_sub(blocks, &mddev->recovery_active);
+	wake_up(&mddev->recovery_wait);
+	if (!ok) {
+		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+		set_bit(MD_RECOVERY_ERROR, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+		// stop recovery, signal do_sync ....
+	}
+}
+EXPORT_SYMBOL(md_done_sync);
+
+/* md_write_start(mddev, bi)
+ * If we need to update some array metadata (e.g. 'active' flag
+ * in superblock) before writing, schedule a superblock update
+ * and wait for it to complete.
+ */
+void md_write_start(struct mddev *mddev, struct bio *bi)
+{
+	int did_change = 0;
+	if (bio_data_dir(bi) != WRITE)
+		return;
+
+	BUG_ON(mddev->ro == 1);
+	if (mddev->ro == 2) {
+		/* need to switch to read/write */
+		mddev->ro = 0;
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+		md_wakeup_thread(mddev->sync_thread);
+		did_change = 1;
+	}
+	atomic_inc(&mddev->writes_pending);
+	if (mddev->safemode == 1)
+		mddev->safemode = 0;
+	if (mddev->in_sync) {
+		spin_lock(&mddev->lock);
+		if (mddev->in_sync) {
+			mddev->in_sync = 0;
+			set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+			set_bit(MD_CHANGE_PENDING, &mddev->flags);
+			md_wakeup_thread(mddev->thread);
+			did_change = 1;
+		}
+		spin_unlock(&mddev->lock);
+	}
+	if (did_change)
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+	wait_event(mddev->sb_wait,
+		   !test_bit(MD_CHANGE_PENDING, &mddev->flags));
+}
+EXPORT_SYMBOL(md_write_start);
+
+void md_write_end(struct mddev *mddev)
+{
+	if (atomic_dec_and_test(&mddev->writes_pending)) {
+		if (mddev->safemode == 2)
+			md_wakeup_thread(mddev->thread);
+		else if (mddev->safemode_delay)
+			mod_timer(&mddev->safemode_timer, jiffies + mddev->safemode_delay);
+	}
+}
+EXPORT_SYMBOL(md_write_end);
+
+/* md_allow_write(mddev)
+ * Calling this ensures that the array is marked 'active' so that writes
+ * may proceed without blocking.  It is important to call this before
+ * attempting a GFP_KERNEL allocation while holding the mddev lock.
+ * Must be called with mddev_lock held.
+ *
+ * In the ->external case MD_CHANGE_CLEAN can not be cleared until mddev->lock
+ * is dropped, so return -EAGAIN after notifying userspace.
+ */
+int md_allow_write(struct mddev *mddev)
+{
+	if (!mddev->pers)
+		return 0;
+	if (mddev->ro)
+		return 0;
+	if (!mddev->pers->sync_request)
+		return 0;
+
+	spin_lock(&mddev->lock);
+	if (mddev->in_sync) {
+		mddev->in_sync = 0;
+		set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+		set_bit(MD_CHANGE_PENDING, &mddev->flags);
+		if (mddev->safemode_delay &&
+		    mddev->safemode == 0)
+			mddev->safemode = 1;
+		spin_unlock(&mddev->lock);
+		if (mddev_is_clustered(mddev))
+			md_cluster_ops->metadata_update_start(mddev);
+		md_update_sb(mddev, 0);
+		if (mddev_is_clustered(mddev))
+			md_cluster_ops->metadata_update_finish(mddev);
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+	} else
+		spin_unlock(&mddev->lock);
+
+	if (test_bit(MD_CHANGE_PENDING, &mddev->flags))
+		return -EAGAIN;
+	else
+		return 0;
+}
+EXPORT_SYMBOL_GPL(md_allow_write);
+
+#define SYNC_MARKS	10
+#define	SYNC_MARK_STEP	(3*HZ)
+#define UPDATE_FREQUENCY (5*60*HZ)
+void md_do_sync(struct md_thread *thread)
+{
+	struct mddev *mddev = thread->mddev;
+	struct mddev *mddev2;
+	unsigned int currspeed = 0,
+		 window;
+	sector_t max_sectors,j, io_sectors, recovery_done;
+	unsigned long mark[SYNC_MARKS];
+	unsigned long update_time;
+	sector_t mark_cnt[SYNC_MARKS];
+	int last_mark,m;
+	struct list_head *tmp;
+	sector_t last_check;
+	int skipped = 0;
+	struct md_rdev *rdev;
+	char *desc, *action = NULL;
+	struct blk_plug plug;
+
+	/* just incase thread restarts... */
+	if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
+		return;
+	if (mddev->ro) {/* never try to sync a read-only array */
+		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+		return;
+	}
+
+	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
+		if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
+			desc = "data-check";
+			action = "check";
+		} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+			desc = "requested-resync";
+			action = "repair";
+		} else
+			desc = "resync";
+	} else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		desc = "reshape";
+	else
+		desc = "recovery";
+
+	mddev->last_sync_action = action ?: desc;
+
+	/* we overload curr_resync somewhat here.
+	 * 0 == not engaged in resync at all
+	 * 2 == checking that there is no conflict with another sync
+	 * 1 == like 2, but have yielded to allow conflicting resync to
+	 *		commense
+	 * other == active in resync - this many blocks
+	 *
+	 * Before starting a resync we must have set curr_resync to
+	 * 2, and then checked that every "conflicting" array has curr_resync
+	 * less than ours.  When we find one that is the same or higher
+	 * we wait on resync_wait.  To avoid deadlock, we reduce curr_resync
+	 * to 1 if we choose to yield (based arbitrarily on address of mddev structure).
+	 * This will mean we have to start checking from the beginning again.
+	 *
+	 */
+
+	do {
+		mddev->curr_resync = 2;
+
+	try_again:
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			goto skip;
+		for_each_mddev(mddev2, tmp) {
+			if (mddev2 == mddev)
+				continue;
+			if (!mddev->parallel_resync
+			&&  mddev2->curr_resync
+			&&  match_mddev_units(mddev, mddev2)) {
+				DEFINE_WAIT(wq);
+				if (mddev < mddev2 && mddev->curr_resync == 2) {
+					/* arbitrarily yield */
+					mddev->curr_resync = 1;
+					wake_up(&resync_wait);
+				}
+				if (mddev > mddev2 && mddev->curr_resync == 1)
+					/* no need to wait here, we can wait the next
+					 * time 'round when curr_resync == 2
+					 */
+					continue;
+				/* We need to wait 'interruptible' so as not to
+				 * contribute to the load average, and not to
+				 * be caught by 'softlockup'
+				 */
+				prepare_to_wait(&resync_wait, &wq, TASK_INTERRUPTIBLE);
+				if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
+				    mddev2->curr_resync >= mddev->curr_resync) {
+					printk(KERN_INFO "md: delaying %s of %s"
+					       " until %s has finished (they"
+					       " share one or more physical units)\n",
+					       desc, mdname(mddev), mdname(mddev2));
+					mddev_put(mddev2);
+					if (signal_pending(current))
+						flush_signals(current);
+					schedule();
+					finish_wait(&resync_wait, &wq);
+					goto try_again;
+				}
+				finish_wait(&resync_wait, &wq);
+			}
+		}
+	} while (mddev->curr_resync < 2);
+
+	j = 0;
+	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
+		/* resync follows the size requested by the personality,
+		 * which defaults to physical size, but can be virtual size
+		 */
+		max_sectors = mddev->resync_max_sectors;
+		atomic64_set(&mddev->resync_mismatches, 0);
+		/* we don't use the checkpoint if there's a bitmap */
+		if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+			j = mddev->resync_min;
+		else if (!mddev->bitmap)
+			j = mddev->recovery_cp;
+
+	} else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		max_sectors = mddev->resync_max_sectors;
+	else {
+		/* recovery follows the physical size of devices */
+		max_sectors = mddev->dev_sectors;
+		j = MaxSector;
+		rcu_read_lock();
+		rdev_for_each_rcu(rdev, mddev)
+			if (rdev->raid_disk >= 0 &&
+			    !test_bit(Faulty, &rdev->flags) &&
+			    !test_bit(In_sync, &rdev->flags) &&
+			    rdev->recovery_offset < j)
+				j = rdev->recovery_offset;
+		rcu_read_unlock();
+
+		/* If there is a bitmap, we need to make sure all
+		 * writes that started before we added a spare
+		 * complete before we start doing a recovery.
+		 * Otherwise the write might complete and (via
+		 * bitmap_endwrite) set a bit in the bitmap after the
+		 * recovery has checked that bit and skipped that
+		 * region.
+		 */
+		if (mddev->bitmap) {
+			mddev->pers->quiesce(mddev, 1);
+			mddev->pers->quiesce(mddev, 0);
+		}
+	}
+
+	printk(KERN_INFO "md: %s of RAID array %s\n", desc, mdname(mddev));
+	printk(KERN_INFO "md: minimum _guaranteed_  speed:"
+		" %d KB/sec/disk.\n", speed_min(mddev));
+	printk(KERN_INFO "md: using maximum available idle IO bandwidth "
+	       "(but not more than %d KB/sec) for %s.\n",
+	       speed_max(mddev), desc);
+
+	is_mddev_idle(mddev, 1); /* this initializes IO event counters */
+
+	io_sectors = 0;
+	for (m = 0; m < SYNC_MARKS; m++) {
+		mark[m] = jiffies;
+		mark_cnt[m] = io_sectors;
+	}
+	last_mark = 0;
+	mddev->resync_mark = mark[last_mark];
+	mddev->resync_mark_cnt = mark_cnt[last_mark];
+
+	/*
+	 * Tune reconstruction:
+	 */
+	window = 32*(PAGE_SIZE/512);
+	printk(KERN_INFO "md: using %dk window, over a total of %lluk.\n",
+		window/2, (unsigned long long)max_sectors/2);
+
+	atomic_set(&mddev->recovery_active, 0);
+	last_check = 0;
+
+	if (j>2) {
+		printk(KERN_INFO
+		       "md: resuming %s of %s from checkpoint.\n",
+		       desc, mdname(mddev));
+		mddev->curr_resync = j;
+	} else
+		mddev->curr_resync = 3; /* no longer delayed */
+	mddev->curr_resync_completed = j;
+	sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+	md_new_event(mddev);
+	update_time = jiffies;
+
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->resync_start(mddev, j, max_sectors);
+
+	blk_start_plug(&plug);
+	while (j < max_sectors) {
+		sector_t sectors;
+
+		skipped = 0;
+
+		if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
+		    ((mddev->curr_resync > mddev->curr_resync_completed &&
+		      (mddev->curr_resync - mddev->curr_resync_completed)
+		      > (max_sectors >> 4)) ||
+		     time_after_eq(jiffies, update_time + UPDATE_FREQUENCY) ||
+		     (j - mddev->curr_resync_completed)*2
+		     >= mddev->resync_max - mddev->curr_resync_completed
+			    )) {
+			/* time to update curr_resync_completed */
+			wait_event(mddev->recovery_wait,
+				   atomic_read(&mddev->recovery_active) == 0);
+			mddev->curr_resync_completed = j;
+			if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
+			    j > mddev->recovery_cp)
+				mddev->recovery_cp = j;
+			update_time = jiffies;
+			set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+		}
+
+		while (j >= mddev->resync_max &&
+		       !test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
+			/* As this condition is controlled by user-space,
+			 * we can block indefinitely, so use '_interruptible'
+			 * to avoid triggering warnings.
+			 */
+			flush_signals(current); /* just in case */
+			wait_event_interruptible(mddev->recovery_wait,
+						 mddev->resync_max > j
+						 || test_bit(MD_RECOVERY_INTR,
+							     &mddev->recovery));
+		}
+
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			break;
+
+		sectors = mddev->pers->sync_request(mddev, j, &skipped);
+		if (sectors == 0) {
+			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+			break;
+		}
+
+		if (!skipped) { /* actual IO requested */
+			io_sectors += sectors;
+			atomic_add(sectors, &mddev->recovery_active);
+		}
+
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			break;
+
+		j += sectors;
+		if (j > 2)
+			mddev->curr_resync = j;
+		if (mddev_is_clustered(mddev))
+			md_cluster_ops->resync_info_update(mddev, j, max_sectors);
+		mddev->curr_mark_cnt = io_sectors;
+		if (last_check == 0)
+			/* this is the earliest that rebuild will be
+			 * visible in /proc/mdstat
+			 */
+			md_new_event(mddev);
+
+		if (last_check + window > io_sectors || j == max_sectors)
+			continue;
+
+		last_check = io_sectors;
+	repeat:
+		if (time_after_eq(jiffies, mark[last_mark] + SYNC_MARK_STEP )) {
+			/* step marks */
+			int next = (last_mark+1) % SYNC_MARKS;
+
+			mddev->resync_mark = mark[next];
+			mddev->resync_mark_cnt = mark_cnt[next];
+			mark[next] = jiffies;
+			mark_cnt[next] = io_sectors - atomic_read(&mddev->recovery_active);
+			last_mark = next;
+		}
+
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			break;
+
+		/*
+		 * this loop exits only if either when we are slower than
+		 * the 'hard' speed limit, or the system was IO-idle for
+		 * a jiffy.
+		 * the system might be non-idle CPU-wise, but we only care
+		 * about not overloading the IO subsystem. (things like an
+		 * e2fsck being done on the RAID array should execute fast)
+		 */
+		cond_resched();
+
+		recovery_done = io_sectors - atomic_read(&mddev->recovery_active);
+		currspeed = ((unsigned long)(recovery_done - mddev->resync_mark_cnt))/2
+			/((jiffies-mddev->resync_mark)/HZ +1) +1;
+
+		if (currspeed > speed_min(mddev)) {
+			if (currspeed > speed_max(mddev)) {
+				msleep(500);
+				goto repeat;
+			}
+			if (!is_mddev_idle(mddev, 0)) {
+				/*
+				 * Give other IO more of a chance.
+				 * The faster the devices, the less we wait.
+				 */
+				wait_event(mddev->recovery_wait,
+					   !atomic_read(&mddev->recovery_active));
+			}
+		}
+	}
+	printk(KERN_INFO "md: %s: %s %s.\n",mdname(mddev), desc,
+	       test_bit(MD_RECOVERY_INTR, &mddev->recovery)
+	       ? "interrupted" : "done");
+	/*
+	 * this also signals 'finished resyncing' to md_stop
+	 */
+	blk_finish_plug(&plug);
+	wait_event(mddev->recovery_wait, !atomic_read(&mddev->recovery_active));
+
+	/* tell personality that we are finished */
+	mddev->pers->sync_request(mddev, max_sectors, &skipped);
+
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->resync_finish(mddev);
+
+	if (!test_bit(MD_RECOVERY_CHECK, &mddev->recovery) &&
+	    mddev->curr_resync > 2) {
+		if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
+			if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
+				if (mddev->curr_resync >= mddev->recovery_cp) {
+					printk(KERN_INFO
+					       "md: checkpointing %s of %s.\n",
+					       desc, mdname(mddev));
+					if (test_bit(MD_RECOVERY_ERROR,
+						&mddev->recovery))
+						mddev->recovery_cp =
+							mddev->curr_resync_completed;
+					else
+						mddev->recovery_cp =
+							mddev->curr_resync;
+				}
+			} else
+				mddev->recovery_cp = MaxSector;
+		} else {
+			if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+				mddev->curr_resync = MaxSector;
+			rcu_read_lock();
+			rdev_for_each_rcu(rdev, mddev)
+				if (rdev->raid_disk >= 0 &&
+				    mddev->delta_disks >= 0 &&
+				    !test_bit(Faulty, &rdev->flags) &&
+				    !test_bit(In_sync, &rdev->flags) &&
+				    rdev->recovery_offset < mddev->curr_resync)
+					rdev->recovery_offset = mddev->curr_resync;
+			rcu_read_unlock();
+		}
+	}
+ skip:
+	set_bit(MD_CHANGE_DEVS, &mddev->flags);
+
+	spin_lock(&mddev->lock);
+	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
+		/* We completed so min/max setting can be forgotten if used. */
+		if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+			mddev->resync_min = 0;
+		mddev->resync_max = MaxSector;
+	} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+		mddev->resync_min = mddev->curr_resync_completed;
+	mddev->curr_resync = 0;
+	spin_unlock(&mddev->lock);
+
+	wake_up(&resync_wait);
+	set_bit(MD_RECOVERY_DONE, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	return;
+}
+EXPORT_SYMBOL_GPL(md_do_sync);
+
+static int remove_and_add_spares(struct mddev *mddev,
+				 struct md_rdev *this)
+{
+	struct md_rdev *rdev;
+	int spares = 0;
+	int removed = 0;
+
+	rdev_for_each(rdev, mddev)
+		if ((this == NULL || rdev == this) &&
+		    rdev->raid_disk >= 0 &&
+		    !test_bit(Blocked, &rdev->flags) &&
+		    (test_bit(Faulty, &rdev->flags) ||
+		     ! test_bit(In_sync, &rdev->flags)) &&
+		    atomic_read(&rdev->nr_pending)==0) {
+			if (mddev->pers->hot_remove_disk(
+				    mddev, rdev) == 0) {
+				sysfs_unlink_rdev(mddev, rdev);
+				rdev->raid_disk = -1;
+				removed++;
+			}
+		}
+	if (removed && mddev->kobj.sd)
+		sysfs_notify(&mddev->kobj, NULL, "degraded");
+
+	if (this)
+		goto no_add;
+
+	rdev_for_each(rdev, mddev) {
+		if (rdev->raid_disk >= 0 &&
+		    !test_bit(In_sync, &rdev->flags) &&
+		    !test_bit(Faulty, &rdev->flags))
+			spares++;
+		if (rdev->raid_disk >= 0)
+			continue;
+		if (test_bit(Faulty, &rdev->flags))
+			continue;
+		if (mddev->ro &&
+		    ! (rdev->saved_raid_disk >= 0 &&
+		       !test_bit(Bitmap_sync, &rdev->flags)))
+			continue;
+
+		if (rdev->saved_raid_disk < 0)
+			rdev->recovery_offset = 0;
+		if (mddev->pers->
+		    hot_add_disk(mddev, rdev) == 0) {
+			if (sysfs_link_rdev(mddev, rdev))
+				/* failure here is OK */;
+			spares++;
+			md_new_event(mddev);
+			set_bit(MD_CHANGE_DEVS, &mddev->flags);
+		}
+	}
+no_add:
+	if (removed)
+		set_bit(MD_CHANGE_DEVS, &mddev->flags);
+	return spares;
+}
+
+static void md_start_sync(struct work_struct *ws)
+{
+	struct mddev *mddev = container_of(ws, struct mddev, del_work);
+
+	mddev->sync_thread = md_register_thread(md_do_sync,
+						mddev,
+						"resync");
+	if (!mddev->sync_thread) {
+		printk(KERN_ERR "%s: could not start resync"
+		       " thread...\n",
+		       mdname(mddev));
+		/* leave the spares where they are, it shouldn't hurt */
+		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+		clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+		clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+		clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+		wake_up(&resync_wait);
+		if (test_and_clear_bit(MD_RECOVERY_RECOVER,
+				       &mddev->recovery))
+			if (mddev->sysfs_action)
+				sysfs_notify_dirent_safe(mddev->sysfs_action);
+	} else
+		md_wakeup_thread(mddev->sync_thread);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+	md_new_event(mddev);
+}
+
+/*
+ * This routine is regularly called by all per-raid-array threads to
+ * deal with generic issues like resync and super-block update.
+ * Raid personalities that don't have a thread (linear/raid0) do not
+ * need this as they never do any recovery or update the superblock.
+ *
+ * It does not do any resync itself, but rather "forks" off other threads
+ * to do that as needed.
+ * When it is determined that resync is needed, we set MD_RECOVERY_RUNNING in
+ * "->recovery" and create a thread at ->sync_thread.
+ * When the thread finishes it sets MD_RECOVERY_DONE
+ * and wakeups up this thread which will reap the thread and finish up.
+ * This thread also removes any faulty devices (with nr_pending == 0).
+ *
+ * The overall approach is:
+ *  1/ if the superblock needs updating, update it.
+ *  2/ If a recovery thread is running, don't do anything else.
+ *  3/ If recovery has finished, clean up, possibly marking spares active.
+ *  4/ If there are any faulty devices, remove them.
+ *  5/ If array is degraded, try to add spares devices
+ *  6/ If array has spares or is not in-sync, start a resync thread.
+ */
+void md_check_recovery(struct mddev *mddev)
+{
+	if (mddev->suspended)
+		return;
+
+	if (mddev->bitmap)
+		bitmap_daemon_work(mddev);
+
+	if (signal_pending(current)) {
+		if (mddev->pers->sync_request && !mddev->external) {
+			printk(KERN_INFO "md: %s in immediate safe mode\n",
+			       mdname(mddev));
+			mddev->safemode = 2;
+		}
+		flush_signals(current);
+	}
+
+	if (mddev->ro && !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
+		return;
+	if ( ! (
+		(mddev->flags & MD_UPDATE_SB_FLAGS & ~ (1<<MD_CHANGE_PENDING)) ||
+		test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
+		test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
+		(mddev->external == 0 && mddev->safemode == 1) ||
+		(mddev->safemode == 2 && ! atomic_read(&mddev->writes_pending)
+		 && !mddev->in_sync && mddev->recovery_cp == MaxSector)
+		))
+		return;
+
+	if (mddev_trylock(mddev)) {
+		int spares = 0;
+
+		if (mddev->ro) {
+			/* On a read-only array we can:
+			 * - remove failed devices
+			 * - add already-in_sync devices if the array itself
+			 *   is in-sync.
+			 * As we only add devices that are already in-sync,
+			 * we can activate the spares immediately.
+			 */
+			remove_and_add_spares(mddev, NULL);
+			/* There is no thread, but we need to call
+			 * ->spare_active and clear saved_raid_disk
+			 */
+			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+			md_reap_sync_thread(mddev);
+			clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			goto unlock;
+		}
+
+		if (!mddev->external) {
+			int did_change = 0;
+			spin_lock(&mddev->lock);
+			if (mddev->safemode &&
+			    !atomic_read(&mddev->writes_pending) &&
+			    !mddev->in_sync &&
+			    mddev->recovery_cp == MaxSector) {
+				mddev->in_sync = 1;
+				did_change = 1;
+				set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+			}
+			if (mddev->safemode == 1)
+				mddev->safemode = 0;
+			spin_unlock(&mddev->lock);
+			if (did_change)
+				sysfs_notify_dirent_safe(mddev->sysfs_state);
+		}
+
+		if (mddev->flags & MD_UPDATE_SB_FLAGS) {
+			if (mddev_is_clustered(mddev))
+				md_cluster_ops->metadata_update_start(mddev);
+			md_update_sb(mddev, 0);
+			if (mddev_is_clustered(mddev))
+				md_cluster_ops->metadata_update_finish(mddev);
+		}
+
+		if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
+		    !test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
+			/* resync/recovery still happening */
+			clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			goto unlock;
+		}
+		if (mddev->sync_thread) {
+			md_reap_sync_thread(mddev);
+			goto unlock;
+		}
+		/* Set RUNNING before clearing NEEDED to avoid
+		 * any transients in the value of "sync_action".
+		 */
+		mddev->curr_resync_completed = 0;
+		spin_lock(&mddev->lock);
+		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+		spin_unlock(&mddev->lock);
+		/* Clear some bits that don't mean anything, but
+		 * might be left set
+		 */
+		clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
+		clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
+
+		if (!test_and_clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
+		    test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+			goto not_running;
+		/* no recovery is running.
+		 * remove any failed drives, then
+		 * add spares if possible.
+		 * Spares are also removed and re-added, to allow
+		 * the personality to fail the re-add.
+		 */
+
+		if (mddev->reshape_position != MaxSector) {
+			if (mddev->pers->check_reshape == NULL ||
+			    mddev->pers->check_reshape(mddev) != 0)
+				/* Cannot proceed */
+				goto not_running;
+			set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+			clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+		} else if ((spares = remove_and_add_spares(mddev, NULL))) {
+			clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+			clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+			clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+			set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+		} else if (mddev->recovery_cp < MaxSector) {
+			set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+			clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+		} else if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
+			/* nothing to be done ... */
+			goto not_running;
+
+		if (mddev->pers->sync_request) {
+			if (spares) {
+				/* We are adding a device or devices to an array
+				 * which has the bitmap stored on all devices.
+				 * So make sure all bitmap pages get written
+				 */
+				bitmap_write_all(mddev->bitmap);
+			}
+			INIT_WORK(&mddev->del_work, md_start_sync);
+			queue_work(md_misc_wq, &mddev->del_work);
+			goto unlock;
+		}
+	not_running:
+		if (!mddev->sync_thread) {
+			clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+			wake_up(&resync_wait);
+			if (test_and_clear_bit(MD_RECOVERY_RECOVER,
+					       &mddev->recovery))
+				if (mddev->sysfs_action)
+					sysfs_notify_dirent_safe(mddev->sysfs_action);
+		}
+	unlock:
+		wake_up(&mddev->sb_wait);
+		mddev_unlock(mddev);
+	}
+}
+EXPORT_SYMBOL(md_check_recovery);
+
+void md_reap_sync_thread(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+
+	/* resync has finished, collect result */
+	md_unregister_thread(&mddev->sync_thread);
+	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
+	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+		/* success...*/
+		/* activate any spares */
+		if (mddev->pers->spare_active(mddev)) {
+			sysfs_notify(&mddev->kobj, NULL,
+				     "degraded");
+			set_bit(MD_CHANGE_DEVS, &mddev->flags);
+		}
+	}
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_start(mddev);
+	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
+	    mddev->pers->finish_reshape)
+		mddev->pers->finish_reshape(mddev);
+
+	/* If array is no-longer degraded, then any saved_raid_disk
+	 * information must be scrapped.
+	 */
+	if (!mddev->degraded)
+		rdev_for_each(rdev, mddev)
+			rdev->saved_raid_disk = -1;
+
+	md_update_sb(mddev, 1);
+	if (mddev_is_clustered(mddev))
+		md_cluster_ops->metadata_update_finish(mddev);
+	clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
+	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+	clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+	clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+	wake_up(&resync_wait);
+	/* flag recovery needed just to double check */
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+	md_new_event(mddev);
+	if (mddev->event_work.func)
+		queue_work(md_misc_wq, &mddev->event_work);
+}
+EXPORT_SYMBOL(md_reap_sync_thread);
+
+void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev)
+{
+	sysfs_notify_dirent_safe(rdev->sysfs_state);
+	wait_event_timeout(rdev->blocked_wait,
+			   !test_bit(Blocked, &rdev->flags) &&
+			   !test_bit(BlockedBadBlocks, &rdev->flags),
+			   msecs_to_jiffies(5000));
+	rdev_dec_pending(rdev, mddev);
+}
+EXPORT_SYMBOL(md_wait_for_blocked_rdev);
+
+void md_finish_reshape(struct mddev *mddev)
+{
+	/* called be personality module when reshape completes. */
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, mddev) {
+		if (rdev->data_offset > rdev->new_data_offset)
+			rdev->sectors += rdev->data_offset - rdev->new_data_offset;
+		else
+			rdev->sectors -= rdev->new_data_offset - rdev->data_offset;
+		rdev->data_offset = rdev->new_data_offset;
+	}
+}
+EXPORT_SYMBOL(md_finish_reshape);
+
+/* Bad block management.
+ * We can record which blocks on each device are 'bad' and so just
+ * fail those blocks, or that stripe, rather than the whole device.
+ * Entries in the bad-block table are 64bits wide.  This comprises:
+ * Length of bad-range, in sectors: 0-511 for lengths 1-512
+ * Start of bad-range, sector offset, 54 bits (allows 8 exbibytes)
+ *  A 'shift' can be set so that larger blocks are tracked and
+ *  consequently larger devices can be covered.
+ * 'Acknowledged' flag - 1 bit. - the most significant bit.
+ *
+ * Locking of the bad-block table uses a seqlock so md_is_badblock
+ * might need to retry if it is very unlucky.
+ * We will sometimes want to check for bad blocks in a bi_end_io function,
+ * so we use the write_seqlock_irq variant.
+ *
+ * When looking for a bad block we specify a range and want to
+ * know if any block in the range is bad.  So we binary-search
+ * to the last range that starts at-or-before the given endpoint,
+ * (or "before the sector after the target range")
+ * then see if it ends after the given start.
+ * We return
+ *  0 if there are no known bad blocks in the range
+ *  1 if there are known bad block which are all acknowledged
+ * -1 if there are bad blocks which have not yet been acknowledged in metadata.
+ * plus the start/length of the first bad section we overlap.
+ */
+int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
+		   sector_t *first_bad, int *bad_sectors)
+{
+	int hi;
+	int lo;
+	u64 *p = bb->page;
+	int rv;
+	sector_t target = s + sectors;
+	unsigned seq;
+
+	if (bb->shift > 0) {
+		/* round the start down, and the end up */
+		s >>= bb->shift;
+		target += (1<<bb->shift) - 1;
+		target >>= bb->shift;
+		sectors = target - s;
+	}
+	/* 'target' is now the first block after the bad range */
+
+retry:
+	seq = read_seqbegin(&bb->lock);
+	lo = 0;
+	rv = 0;
+	hi = bb->count;
+
+	/* Binary search between lo and hi for 'target'
+	 * i.e. for the last range that starts before 'target'
+	 */
+	/* INVARIANT: ranges before 'lo' and at-or-after 'hi'
+	 * are known not to be the last range before target.
+	 * VARIANT: hi-lo is the number of possible
+	 * ranges, and decreases until it reaches 1
+	 */
+	while (hi - lo > 1) {
+		int mid = (lo + hi) / 2;
+		sector_t a = BB_OFFSET(p[mid]);
+		if (a < target)
+			/* This could still be the one, earlier ranges
+			 * could not. */
+			lo = mid;
+		else
+			/* This and later ranges are definitely out. */
+			hi = mid;
+	}
+	/* 'lo' might be the last that started before target, but 'hi' isn't */
+	if (hi > lo) {
+		/* need to check all range that end after 's' to see if
+		 * any are unacknowledged.
+		 */
+		while (lo >= 0 &&
+		       BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {
+			if (BB_OFFSET(p[lo]) < target) {
+				/* starts before the end, and finishes after
+				 * the start, so they must overlap
+				 */
+				if (rv != -1 && BB_ACK(p[lo]))
+					rv = 1;
+				else
+					rv = -1;
+				*first_bad = BB_OFFSET(p[lo]);
+				*bad_sectors = BB_LEN(p[lo]);
+			}
+			lo--;
+		}
+	}
+
+	if (read_seqretry(&bb->lock, seq))
+		goto retry;
+
+	return rv;
+}
+EXPORT_SYMBOL_GPL(md_is_badblock);
+
+/*
+ * Add a range of bad blocks to the table.
+ * This might extend the table, or might contract it
+ * if two adjacent ranges can be merged.
+ * We binary-search to find the 'insertion' point, then
+ * decide how best to handle it.
+ */
+static int md_set_badblocks(struct badblocks *bb, sector_t s, int sectors,
+			    int acknowledged)
+{
+	u64 *p;
+	int lo, hi;
+	int rv = 1;
+	unsigned long flags;
+
+	if (bb->shift < 0)
+		/* badblocks are disabled */
+		return 0;
+
+	if (bb->shift) {
+		/* round the start down, and the end up */
+		sector_t next = s + sectors;
+		s >>= bb->shift;
+		next += (1<<bb->shift) - 1;
+		next >>= bb->shift;
+		sectors = next - s;
+	}
+
+	write_seqlock_irqsave(&bb->lock, flags);
+
+	p = bb->page;
+	lo = 0;
+	hi = bb->count;
+	/* Find the last range that starts at-or-before 's' */
+	while (hi - lo > 1) {
+		int mid = (lo + hi) / 2;
+		sector_t a = BB_OFFSET(p[mid]);
+		if (a <= s)
+			lo = mid;
+		else
+			hi = mid;
+	}
+	if (hi > lo && BB_OFFSET(p[lo]) > s)
+		hi = lo;
+
+	if (hi > lo) {
+		/* we found a range that might merge with the start
+		 * of our new range
+		 */
+		sector_t a = BB_OFFSET(p[lo]);
+		sector_t e = a + BB_LEN(p[lo]);
+		int ack = BB_ACK(p[lo]);
+		if (e >= s) {
+			/* Yes, we can merge with a previous range */
+			if (s == a && s + sectors >= e)
+				/* new range covers old */
+				ack = acknowledged;
+			else
+				ack = ack && acknowledged;
+
+			if (e < s + sectors)
+				e = s + sectors;
+			if (e - a <= BB_MAX_LEN) {
+				p[lo] = BB_MAKE(a, e-a, ack);
+				s = e;
+			} else {
+				/* does not all fit in one range,
+				 * make p[lo] maximal
+				 */
+				if (BB_LEN(p[lo]) != BB_MAX_LEN)
+					p[lo] = BB_MAKE(a, BB_MAX_LEN, ack);
+				s = a + BB_MAX_LEN;
+			}
+			sectors = e - s;
+		}
+	}
+	if (sectors && hi < bb->count) {
+		/* 'hi' points to the first range that starts after 's'.
+		 * Maybe we can merge with the start of that range */
+		sector_t a = BB_OFFSET(p[hi]);
+		sector_t e = a + BB_LEN(p[hi]);
+		int ack = BB_ACK(p[hi]);
+		if (a <= s + sectors) {
+			/* merging is possible */
+			if (e <= s + sectors) {
+				/* full overlap */
+				e = s + sectors;
+				ack = acknowledged;
+			} else
+				ack = ack && acknowledged;
+
+			a = s;
+			if (e - a <= BB_MAX_LEN) {
+				p[hi] = BB_MAKE(a, e-a, ack);
+				s = e;
+			} else {
+				p[hi] = BB_MAKE(a, BB_MAX_LEN, ack);
+				s = a + BB_MAX_LEN;
+			}
+			sectors = e - s;
+			lo = hi;
+			hi++;
+		}
+	}
+	if (sectors == 0 && hi < bb->count) {
+		/* we might be able to combine lo and hi */
+		/* Note: 's' is at the end of 'lo' */
+		sector_t a = BB_OFFSET(p[hi]);
+		int lolen = BB_LEN(p[lo]);
+		int hilen = BB_LEN(p[hi]);
+		int newlen = lolen + hilen - (s - a);
+		if (s >= a && newlen < BB_MAX_LEN) {
+			/* yes, we can combine them */
+			int ack = BB_ACK(p[lo]) && BB_ACK(p[hi]);
+			p[lo] = BB_MAKE(BB_OFFSET(p[lo]), newlen, ack);
+			memmove(p + hi, p + hi + 1,
+				(bb->count - hi - 1) * 8);
+			bb->count--;
+		}
+	}
+	while (sectors) {
+		/* didn't merge (it all).
+		 * Need to add a range just before 'hi' */
+		if (bb->count >= MD_MAX_BADBLOCKS) {
+			/* No room for more */
+			rv = 0;
+			break;
+		} else {
+			int this_sectors = sectors;
+			memmove(p + hi + 1, p + hi,
+				(bb->count - hi) * 8);
+			bb->count++;
+
+			if (this_sectors > BB_MAX_LEN)
+				this_sectors = BB_MAX_LEN;
+			p[hi] = BB_MAKE(s, this_sectors, acknowledged);
+			sectors -= this_sectors;
+			s += this_sectors;
+		}
+	}
+
+	bb->changed = 1;
+	if (!acknowledged)
+		bb->unacked_exist = 1;
+	write_sequnlock_irqrestore(&bb->lock, flags);
+
+	return rv;
+}
+
+int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
+		       int is_new)
+{
+	int rv;
+	if (is_new)
+		s += rdev->new_data_offset;
+	else
+		s += rdev->data_offset;
+	rv = md_set_badblocks(&rdev->badblocks,
+			      s, sectors, 0);
+	if (rv) {
+		/* Make sure they get written out promptly */
+		sysfs_notify_dirent_safe(rdev->sysfs_state);
+		set_bit(MD_CHANGE_CLEAN, &rdev->mddev->flags);
+		md_wakeup_thread(rdev->mddev->thread);
+	}
+	return rv;
+}
+EXPORT_SYMBOL_GPL(rdev_set_badblocks);
+
+/*
+ * Remove a range of bad blocks from the table.
+ * This may involve extending the table if we spilt a region,
+ * but it must not fail.  So if the table becomes full, we just
+ * drop the remove request.
+ */
+static int md_clear_badblocks(struct badblocks *bb, sector_t s, int sectors)
+{
+	u64 *p;
+	int lo, hi;
+	sector_t target = s + sectors;
+	int rv = 0;
+
+	if (bb->shift > 0) {
+		/* When clearing we round the start up and the end down.
+		 * This should not matter as the shift should align with
+		 * the block size and no rounding should ever be needed.
+		 * However it is better the think a block is bad when it
+		 * isn't than to think a block is not bad when it is.
+		 */
+		s += (1<<bb->shift) - 1;
+		s >>= bb->shift;
+		target >>= bb->shift;
+		sectors = target - s;
+	}
+
+	write_seqlock_irq(&bb->lock);
+
+	p = bb->page;
+	lo = 0;
+	hi = bb->count;
+	/* Find the last range that starts before 'target' */
+	while (hi - lo > 1) {
+		int mid = (lo + hi) / 2;
+		sector_t a = BB_OFFSET(p[mid]);
+		if (a < target)
+			lo = mid;
+		else
+			hi = mid;
+	}
+	if (hi > lo) {
+		/* p[lo] is the last range that could overlap the
+		 * current range.  Earlier ranges could also overlap,
+		 * but only this one can overlap the end of the range.
+		 */
+		if (BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > target) {
+			/* Partial overlap, leave the tail of this range */
+			int ack = BB_ACK(p[lo]);
+			sector_t a = BB_OFFSET(p[lo]);
+			sector_t end = a + BB_LEN(p[lo]);
+
+			if (a < s) {
+				/* we need to split this range */
+				if (bb->count >= MD_MAX_BADBLOCKS) {
+					rv = -ENOSPC;
+					goto out;
+				}
+				memmove(p+lo+1, p+lo, (bb->count - lo) * 8);
+				bb->count++;
+				p[lo] = BB_MAKE(a, s-a, ack);
+				lo++;
+			}
+			p[lo] = BB_MAKE(target, end - target, ack);
+			/* there is no longer an overlap */
+			hi = lo;
+			lo--;
+		}
+		while (lo >= 0 &&
+		       BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {
+			/* This range does overlap */
+			if (BB_OFFSET(p[lo]) < s) {
+				/* Keep the early parts of this range. */
+				int ack = BB_ACK(p[lo]);
+				sector_t start = BB_OFFSET(p[lo]);
+				p[lo] = BB_MAKE(start, s - start, ack);
+				/* now low doesn't overlap, so.. */
+				break;
+			}
+			lo--;
+		}
+		/* 'lo' is strictly before, 'hi' is strictly after,
+		 * anything between needs to be discarded
+		 */
+		if (hi - lo > 1) {
+			memmove(p+lo+1, p+hi, (bb->count - hi) * 8);
+			bb->count -= (hi - lo - 1);
+		}
+	}
+
+	bb->changed = 1;
+out:
+	write_sequnlock_irq(&bb->lock);
+	return rv;
+}
+
+int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
+			 int is_new)
+{
+	if (is_new)
+		s += rdev->new_data_offset;
+	else
+		s += rdev->data_offset;
+	return md_clear_badblocks(&rdev->badblocks,
+				  s, sectors);
+}
+EXPORT_SYMBOL_GPL(rdev_clear_badblocks);
+
+/*
+ * Acknowledge all bad blocks in a list.
+ * This only succeeds if ->changed is clear.  It is used by
+ * in-kernel metadata updates
+ */
+void md_ack_all_badblocks(struct badblocks *bb)
+{
+	if (bb->page == NULL || bb->changed)
+		/* no point even trying */
+		return;
+	write_seqlock_irq(&bb->lock);
+
+	if (bb->changed == 0 && bb->unacked_exist) {
+		u64 *p = bb->page;
+		int i;
+		for (i = 0; i < bb->count ; i++) {
+			if (!BB_ACK(p[i])) {
+				sector_t start = BB_OFFSET(p[i]);
+				int len = BB_LEN(p[i]);
+				p[i] = BB_MAKE(start, len, 1);
+			}
+		}
+		bb->unacked_exist = 0;
+	}
+	write_sequnlock_irq(&bb->lock);
+}
+EXPORT_SYMBOL_GPL(md_ack_all_badblocks);
+
+/* sysfs access to bad-blocks list.
+ * We present two files.
+ * 'bad-blocks' lists sector numbers and lengths of ranges that
+ *    are recorded as bad.  The list is truncated to fit within
+ *    the one-page limit of sysfs.
+ *    Writing "sector length" to this file adds an acknowledged
+ *    bad block list.
+ * 'unacknowledged-bad-blocks' lists bad blocks that have not yet
+ *    been acknowledged.  Writing to this file adds bad blocks
+ *    without acknowledging them.  This is largely for testing.
+ */
+
+static ssize_t
+badblocks_show(struct badblocks *bb, char *page, int unack)
+{
+	size_t len;
+	int i;
+	u64 *p = bb->page;
+	unsigned seq;
+
+	if (bb->shift < 0)
+		return 0;
+
+retry:
+	seq = read_seqbegin(&bb->lock);
+
+	len = 0;
+	i = 0;
+
+	while (len < PAGE_SIZE && i < bb->count) {
+		sector_t s = BB_OFFSET(p[i]);
+		unsigned int length = BB_LEN(p[i]);
+		int ack = BB_ACK(p[i]);
+		i++;
+
+		if (unack && ack)
+			continue;
+
+		len += snprintf(page+len, PAGE_SIZE-len, "%llu %u\n",
+				(unsigned long long)s << bb->shift,
+				length << bb->shift);
+	}
+	if (unack && len == 0)
+		bb->unacked_exist = 0;
+
+	if (read_seqretry(&bb->lock, seq))
+		goto retry;
+
+	return len;
+}
+
+#define DO_DEBUG 1
+
+static ssize_t
+badblocks_store(struct badblocks *bb, const char *page, size_t len, int unack)
+{
+	unsigned long long sector;
+	int length;
+	char newline;
+#ifdef DO_DEBUG
+	/* Allow clearing via sysfs *only* for testing/debugging.
+	 * Normally only a successful write may clear a badblock
+	 */
+	int clear = 0;
+	if (page[0] == '-') {
+		clear = 1;
+		page++;
+	}
+#endif /* DO_DEBUG */
+
+	switch (sscanf(page, "%llu %d%c", &sector, &length, &newline)) {
+	case 3:
+		if (newline != '\n')
+			return -EINVAL;
+	case 2:
+		if (length <= 0)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+#ifdef DO_DEBUG
+	if (clear) {
+		md_clear_badblocks(bb, sector, length);
+		return len;
+	}
+#endif /* DO_DEBUG */
+	if (md_set_badblocks(bb, sector, length, !unack))
+		return len;
+	else
+		return -ENOSPC;
+}
+
+static int md_notify_reboot(struct notifier_block *this,
+			    unsigned long code, void *x)
+{
+	struct list_head *tmp;
+	struct mddev *mddev;
+	int need_delay = 0;
+
+	for_each_mddev(mddev, tmp) {
+		if (mddev_trylock(mddev)) {
+			if (mddev->pers)
+				__md_stop_writes(mddev);
+			if (mddev->persistent)
+				mddev->safemode = 2;
+			mddev_unlock(mddev);
+		}
+		need_delay = 1;
+	}
+	/*
+	 * certain more exotic SCSI devices are known to be
+	 * volatile wrt too early system reboots. While the
+	 * right place to handle this issue is the given
+	 * driver, we do want to have a safe RAID driver ...
+	 */
+	if (need_delay)
+		mdelay(1000*1);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block md_notifier = {
+	.notifier_call	= md_notify_reboot,
+	.next		= NULL,
+	.priority	= INT_MAX, /* before any real devices */
+};
+
+static void md_geninit(void)
+{
+	pr_debug("md: sizeof(mdp_super_t) = %d\n", (int)sizeof(mdp_super_t));
+
+	proc_create("mdstat", S_IRUGO, NULL, &md_seq_fops);
+}
+
+static int __init md_init(void)
+{
+	int ret = -ENOMEM;
+
+	md_wq = alloc_workqueue("md", WQ_MEM_RECLAIM, 0);
+	if (!md_wq)
+		goto err_wq;
+
+	md_misc_wq = alloc_workqueue("md_misc", 0, 0);
+	if (!md_misc_wq)
+		goto err_misc_wq;
+
+	if ((ret = register_blkdev(MD_MAJOR, "md")) < 0)
+		goto err_md;
+
+	if ((ret = register_blkdev(0, "mdp")) < 0)
+		goto err_mdp;
+	mdp_major = ret;
+
+	blk_register_region(MKDEV(MD_MAJOR, 0), 512, THIS_MODULE,
+			    md_probe, NULL, NULL);
+	blk_register_region(MKDEV(mdp_major, 0), 1UL<<MINORBITS, THIS_MODULE,
+			    md_probe, NULL, NULL);
+
+	register_reboot_notifier(&md_notifier);
+	raid_table_header = register_sysctl_table(raid_root_table);
+
+	md_geninit();
+	return 0;
+
+err_mdp:
+	unregister_blkdev(MD_MAJOR, "md");
+err_md:
+	destroy_workqueue(md_misc_wq);
+err_misc_wq:
+	destroy_workqueue(md_wq);
+err_wq:
+	return ret;
+}
+
+void md_reload_sb(struct mddev *mddev)
+{
+	struct md_rdev *rdev, *tmp;
+
+	rdev_for_each_safe(rdev, tmp, mddev) {
+		rdev->sb_loaded = 0;
+		ClearPageUptodate(rdev->sb_page);
+	}
+	mddev->raid_disks = 0;
+	analyze_sbs(mddev);
+	rdev_for_each_safe(rdev, tmp, mddev) {
+		struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
+		/* since we don't write to faulty devices, we figure out if the
+		 *  disk is faulty by comparing events
+		 */
+		if (mddev->events > sb->events)
+			set_bit(Faulty, &rdev->flags);
+	}
+
+}
+EXPORT_SYMBOL(md_reload_sb);
+
+#ifndef MODULE
+
+/*
+ * Searches all registered partitions for autorun RAID arrays
+ * at boot time.
+ */
+
+static LIST_HEAD(all_detected_devices);
+struct detected_devices_node {
+	struct list_head list;
+	dev_t dev;
+};
+
+void md_autodetect_dev(dev_t dev)
+{
+	struct detected_devices_node *node_detected_dev;
+
+	node_detected_dev = kzalloc(sizeof(*node_detected_dev), GFP_KERNEL);
+	if (node_detected_dev) {
+		node_detected_dev->dev = dev;
+		list_add_tail(&node_detected_dev->list, &all_detected_devices);
+	} else {
+		printk(KERN_CRIT "md: md_autodetect_dev: kzalloc failed"
+			", skipping dev(%d,%d)\n", MAJOR(dev), MINOR(dev));
+	}
+}
+
+static void autostart_arrays(int part)
+{
+	struct md_rdev *rdev;
+	struct detected_devices_node *node_detected_dev;
+	dev_t dev;
+	int i_scanned, i_passed;
+
+	i_scanned = 0;
+	i_passed = 0;
+
+	printk(KERN_INFO "md: Autodetecting RAID arrays.\n");
+
+	while (!list_empty(&all_detected_devices) && i_scanned < INT_MAX) {
+		i_scanned++;
+		node_detected_dev = list_entry(all_detected_devices.next,
+					struct detected_devices_node, list);
+		list_del(&node_detected_dev->list);
+		dev = node_detected_dev->dev;
+		kfree(node_detected_dev);
+		rdev = md_import_device(dev,0, 90);
+		if (IS_ERR(rdev))
+			continue;
+
+		if (test_bit(Faulty, &rdev->flags))
+			continue;
+
+		set_bit(AutoDetected, &rdev->flags);
+		list_add(&rdev->same_set, &pending_raid_disks);
+		i_passed++;
+	}
+
+	printk(KERN_INFO "md: Scanned %d and added %d devices.\n",
+						i_scanned, i_passed);
+
+	autorun_devices(part);
+}
+
+#endif /* !MODULE */
+
+static __exit void md_exit(void)
+{
+	struct mddev *mddev;
+	struct list_head *tmp;
+	int delay = 1;
+
+	blk_unregister_region(MKDEV(MD_MAJOR,0), 512);
+	blk_unregister_region(MKDEV(mdp_major,0), 1U << MINORBITS);
+
+	unregister_blkdev(MD_MAJOR,"md");
+	unregister_blkdev(mdp_major, "mdp");
+	unregister_reboot_notifier(&md_notifier);
+	unregister_sysctl_table(raid_table_header);
+
+	/* We cannot unload the modules while some process is
+	 * waiting for us in select() or poll() - wake them up
+	 */
+	md_unloading = 1;
+	while (waitqueue_active(&md_event_waiters)) {
+		/* not safe to leave yet */
+		wake_up(&md_event_waiters);
+		msleep(delay);
+		delay += delay;
+	}
+	remove_proc_entry("mdstat", NULL);
+
+	for_each_mddev(mddev, tmp) {
+		export_array(mddev);
+		mddev->hold_active = 0;
+	}
+	destroy_workqueue(md_misc_wq);
+	destroy_workqueue(md_wq);
+}
+
+subsys_initcall(md_init);
+module_exit(md_exit)
+
+static int get_ro(char *buffer, struct kernel_param *kp)
+{
+	return sprintf(buffer, "%d", start_readonly);
+}
+static int set_ro(const char *val, struct kernel_param *kp)
+{
+	char *e;
+	int num = simple_strtoul(val, &e, 10);
+	if (*val && (*e == '\0' || *e == '\n')) {
+		start_readonly = num;
+		return 0;
+	}
+	return -EINVAL;
+}
+
+module_param_call(start_ro, set_ro, get_ro, NULL, S_IRUSR|S_IWUSR);
+module_param(start_dirty_degraded, int, S_IRUGO|S_IWUSR);
+module_param_call(new_array, add_named_array, NULL, NULL, S_IWUSR);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MD RAID framework");
+MODULE_ALIAS("md");
+MODULE_ALIAS_BLOCKDEV_MAJOR(MD_MAJOR);