Initial import

1 files changed, 877 insertions, 0 deletions

diff --git a/drivers/staging/lustre/lustre/llite/lloop.c b/drivers/staging/lustre/lustre/llite/lloop.c
new file mode 100644
index 000000000..413a8408e
--- /dev/null
+++ b/drivers/staging/lustre/lustre/llite/lloop.c
@@ -0,0 +1,877 @@
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Use is subject to license terms.
+ *
+ * Copyright (c) 2011, 2012, Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ */
+
+/*
+ *  linux/drivers/block/loop.c
+ *
+ *  Written by Theodore Ts'o, 3/29/93
+ *
+ * Copyright 1993 by Theodore Ts'o.  Redistribution of this file is
+ * permitted under the GNU General Public License.
+ *
+ * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
+ * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
+ *
+ * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
+ *
+ * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
+ *
+ * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
+ *
+ * Loadable modules and other fixes by AK, 1998
+ *
+ * Maximum number of loop devices now dynamic via max_loop module parameter.
+ * Russell Kroll <rkroll@exploits.org> 19990701
+ *
+ * Maximum number of loop devices when compiled-in now selectable by passing
+ * max_loop=<1-255> to the kernel on boot.
+ * Erik I. Bols?, <eriki@himolde.no>, Oct 31, 1999
+ *
+ * Completely rewrite request handling to be make_request_fn style and
+ * non blocking, pushing work to a helper thread. Lots of fixes from
+ * Al Viro too.
+ * Jens Axboe <axboe@suse.de>, Nov 2000
+ *
+ * Support up to 256 loop devices
+ * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
+ *
+ * Support for falling back on the write file operation when the address space
+ * operations prepare_write and/or commit_write are not available on the
+ * backing filesystem.
+ * Anton Altaparmakov, 16 Feb 2005
+ *
+ * Still To Fix:
+ * - Advisory locking is ignored here.
+ * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
+ *
+ */
+
+#include <linux/module.h>
+
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/stat.h>
+#include <linux/errno.h>
+#include <linux/major.h>
+#include <linux/wait.h>
+#include <linux/blkdev.h>
+#include <linux/blkpg.h>
+#include <linux/init.h>
+#include <linux/swap.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+#include <linux/writeback.h>
+#include <linux/buffer_head.h>		/* for invalidate_bdev() */
+#include <linux/completion.h>
+#include <linux/highmem.h>
+#include <linux/gfp.h>
+#include <linux/pagevec.h>
+#include <linux/uaccess.h>
+
+#include "../include/lustre_lib.h"
+#include "../include/lustre_lite.h"
+#include "llite_internal.h"
+
+#define LLOOP_MAX_SEGMENTS	LNET_MAX_IOV
+
+/* Possible states of device */
+enum {
+	LLOOP_UNBOUND,
+	LLOOP_BOUND,
+	LLOOP_RUNDOWN,
+};
+
+struct lloop_device {
+	int		  lo_number;
+	int		  lo_refcnt;
+	loff_t	       lo_offset;
+	loff_t	       lo_sizelimit;
+	int		  lo_flags;
+	struct file	 *lo_backing_file;
+	struct block_device *lo_device;
+	unsigned	     lo_blocksize;
+
+	gfp_t		  old_gfp_mask;
+
+	spinlock_t		lo_lock;
+	struct bio		*lo_bio;
+	struct bio		*lo_biotail;
+	int			lo_state;
+	struct semaphore	lo_sem;
+	struct mutex		lo_ctl_mutex;
+	atomic_t	 lo_pending;
+	wait_queue_head_t	  lo_bh_wait;
+
+	struct request_queue *lo_queue;
+
+	const struct lu_env *lo_env;
+	struct cl_io	 lo_io;
+	struct ll_dio_pages  lo_pvec;
+
+	/* data to handle bio for lustre. */
+	struct lo_request_data {
+		struct page *lrd_pages[LLOOP_MAX_SEGMENTS];
+		loff_t       lrd_offsets[LLOOP_MAX_SEGMENTS];
+	} lo_requests[1];
+};
+
+/*
+ * Loop flags
+ */
+enum {
+	LO_FLAGS_READ_ONLY       = 1,
+};
+
+static int lloop_major;
+#define MAX_LOOP_DEFAULT  16
+static int max_loop = MAX_LOOP_DEFAULT;
+static struct lloop_device *loop_dev;
+static struct gendisk **disks;
+static struct mutex lloop_mutex;
+static void *ll_iocontrol_magic = NULL;
+
+static loff_t get_loop_size(struct lloop_device *lo, struct file *file)
+{
+	loff_t size, offset, loopsize;
+
+	/* Compute loopsize in bytes */
+	size = i_size_read(file->f_mapping->host);
+	offset = lo->lo_offset;
+	loopsize = size - offset;
+	if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
+		loopsize = lo->lo_sizelimit;
+
+	/*
+	 * Unfortunately, if we want to do I/O on the device,
+	 * the number of 512-byte sectors has to fit into a sector_t.
+	 */
+	return loopsize >> 9;
+}
+
+static int do_bio_lustrebacked(struct lloop_device *lo, struct bio *head)
+{
+	const struct lu_env  *env   = lo->lo_env;
+	struct cl_io	 *io    = &lo->lo_io;
+	struct inode	 *inode = file_inode(lo->lo_backing_file);
+	struct cl_object     *obj = ll_i2info(inode)->lli_clob;
+	pgoff_t	       offset;
+	int		   ret;
+	int		   rw;
+	u32		   page_count = 0;
+	struct bio_vec       bvec;
+	struct bvec_iter   iter;
+	struct bio	   *bio;
+	ssize_t	       bytes;
+
+	struct ll_dio_pages  *pvec = &lo->lo_pvec;
+	struct page	 **pages = pvec->ldp_pages;
+	loff_t	       *offsets = pvec->ldp_offsets;
+
+	truncate_inode_pages(inode->i_mapping, 0);
+
+	/* initialize the IO */
+	memset(io, 0, sizeof(*io));
+	io->ci_obj = obj;
+	ret = cl_io_init(env, io, CIT_MISC, obj);
+	if (ret)
+		return io->ci_result;
+	io->ci_lockreq = CILR_NEVER;
+
+	LASSERT(head != NULL);
+	rw = head->bi_rw;
+	for (bio = head; bio != NULL; bio = bio->bi_next) {
+		LASSERT(rw == bio->bi_rw);
+
+		offset = (pgoff_t)(bio->bi_iter.bi_sector << 9) + lo->lo_offset;
+		bio_for_each_segment(bvec, bio, iter) {
+			BUG_ON(bvec.bv_offset != 0);
+			BUG_ON(bvec.bv_len != PAGE_CACHE_SIZE);
+
+			pages[page_count] = bvec.bv_page;
+			offsets[page_count] = offset;
+			page_count++;
+			offset += bvec.bv_len;
+		}
+		LASSERT(page_count <= LLOOP_MAX_SEGMENTS);
+	}
+
+	ll_stats_ops_tally(ll_i2sbi(inode),
+			(rw == WRITE) ? LPROC_LL_BRW_WRITE : LPROC_LL_BRW_READ,
+			page_count);
+
+	pvec->ldp_size = page_count << PAGE_CACHE_SHIFT;
+	pvec->ldp_nr = page_count;
+
+	/* FIXME: in ll_direct_rw_pages, it has to allocate many cl_page{}s to
+	 * write those pages into OST. Even worse case is that more pages
+	 * would be asked to write out to swap space, and then finally get here
+	 * again.
+	 * Unfortunately this is NOT easy to fix.
+	 * Thoughts on solution:
+	 * 0. Define a reserved pool for cl_pages, which could be a list of
+	 *    pre-allocated cl_pages;
+	 * 1. Define a new operation in cl_object_operations{}, says clo_depth,
+	 *    which measures how many layers for this lustre object. Generally
+	 *    speaking, the depth would be 2, one for llite, and one for lovsub.
+	 *    However, for SNS, there will be more since we need additional page
+	 *    to store parity;
+	 * 2. Reserve the # of (page_count * depth) cl_pages from the reserved
+	 *    pool. Afterwards, the clio would allocate the pages from reserved
+	 *    pool, this guarantees we needn't allocate the cl_pages from
+	 *    generic cl_page slab cache.
+	 *    Of course, if there is NOT enough pages in the pool, we might
+	 *    be asked to write less pages once, this purely depends on
+	 *    implementation. Anyway, we should be careful to avoid deadlocking.
+	 */
+	mutex_lock(&inode->i_mutex);
+	bytes = ll_direct_rw_pages(env, io, rw, inode, pvec);
+	mutex_unlock(&inode->i_mutex);
+	cl_io_fini(env, io);
+	return (bytes == pvec->ldp_size) ? 0 : (int)bytes;
+}
+
+/*
+ * Add bio to back of pending list
+ */
+static void loop_add_bio(struct lloop_device *lo, struct bio *bio)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&lo->lo_lock, flags);
+	if (lo->lo_biotail) {
+		lo->lo_biotail->bi_next = bio;
+		lo->lo_biotail = bio;
+	} else
+		lo->lo_bio = lo->lo_biotail = bio;
+	spin_unlock_irqrestore(&lo->lo_lock, flags);
+
+	atomic_inc(&lo->lo_pending);
+	if (waitqueue_active(&lo->lo_bh_wait))
+		wake_up(&lo->lo_bh_wait);
+}
+
+/*
+ * Grab first pending buffer
+ */
+static unsigned int loop_get_bio(struct lloop_device *lo, struct bio **req)
+{
+	struct bio *first;
+	struct bio **bio;
+	unsigned int count = 0;
+	unsigned int page_count = 0;
+	int rw;
+
+	spin_lock_irq(&lo->lo_lock);
+	first = lo->lo_bio;
+	if (unlikely(first == NULL)) {
+		spin_unlock_irq(&lo->lo_lock);
+		return 0;
+	}
+
+	/* TODO: need to split the bio, too bad. */
+	LASSERT(first->bi_vcnt <= LLOOP_MAX_SEGMENTS);
+
+	rw = first->bi_rw;
+	bio = &lo->lo_bio;
+	while (*bio && (*bio)->bi_rw == rw) {
+		CDEBUG(D_INFO, "bio sector %llu size %u count %u vcnt%u \n",
+		       (unsigned long long)(*bio)->bi_iter.bi_sector,
+		       (*bio)->bi_iter.bi_size,
+		       page_count, (*bio)->bi_vcnt);
+		if (page_count + (*bio)->bi_vcnt > LLOOP_MAX_SEGMENTS)
+			break;
+
+
+		page_count += (*bio)->bi_vcnt;
+		count++;
+		bio = &(*bio)->bi_next;
+	}
+	if (*bio) {
+		/* Some of bios can't be mergeable. */
+		lo->lo_bio = *bio;
+		*bio = NULL;
+	} else {
+		/* Hit the end of queue */
+		lo->lo_biotail = NULL;
+		lo->lo_bio = NULL;
+	}
+	*req = first;
+	spin_unlock_irq(&lo->lo_lock);
+	return count;
+}
+
+static void loop_make_request(struct request_queue *q, struct bio *old_bio)
+{
+	struct lloop_device *lo = q->queuedata;
+	int rw = bio_rw(old_bio);
+	int inactive;
+
+	if (!lo)
+		goto err;
+
+	CDEBUG(D_INFO, "submit bio sector %llu size %u\n",
+	       (unsigned long long)old_bio->bi_iter.bi_sector,
+	       old_bio->bi_iter.bi_size);
+
+	spin_lock_irq(&lo->lo_lock);
+	inactive = lo->lo_state != LLOOP_BOUND;
+	spin_unlock_irq(&lo->lo_lock);
+	if (inactive)
+		goto err;
+
+	if (rw == WRITE) {
+		if (lo->lo_flags & LO_FLAGS_READ_ONLY)
+			goto err;
+	} else if (rw == READA) {
+		rw = READ;
+	} else if (rw != READ) {
+		CERROR("lloop: unknown command (%x)\n", rw);
+		goto err;
+	}
+	loop_add_bio(lo, old_bio);
+	return;
+err:
+	cfs_bio_io_error(old_bio, old_bio->bi_iter.bi_size);
+}
+
+
+static inline void loop_handle_bio(struct lloop_device *lo, struct bio *bio)
+{
+	int ret;
+	ret = do_bio_lustrebacked(lo, bio);
+	while (bio) {
+		struct bio *tmp = bio->bi_next;
+		bio->bi_next = NULL;
+		cfs_bio_endio(bio, bio->bi_iter.bi_size, ret);
+		bio = tmp;
+	}
+}
+
+static inline int loop_active(struct lloop_device *lo)
+{
+	return atomic_read(&lo->lo_pending) ||
+		(lo->lo_state == LLOOP_RUNDOWN);
+}
+
+/*
+ * worker thread that handles reads/writes to file backed loop devices,
+ * to avoid blocking in our make_request_fn.
+ */
+static int loop_thread(void *data)
+{
+	struct lloop_device *lo = data;
+	struct bio *bio;
+	unsigned int count;
+	unsigned long times = 0;
+	unsigned long total_count = 0;
+
+	struct lu_env *env;
+	int refcheck;
+	int ret = 0;
+
+	set_user_nice(current, MIN_NICE);
+
+	lo->lo_state = LLOOP_BOUND;
+
+	env = cl_env_get(&refcheck);
+	if (IS_ERR(env)) {
+		ret = PTR_ERR(env);
+		goto out;
+	}
+
+	lo->lo_env = env;
+	memset(&lo->lo_pvec, 0, sizeof(lo->lo_pvec));
+	lo->lo_pvec.ldp_pages   = lo->lo_requests[0].lrd_pages;
+	lo->lo_pvec.ldp_offsets = lo->lo_requests[0].lrd_offsets;
+
+	/*
+	 * up sem, we are running
+	 */
+	up(&lo->lo_sem);
+
+	for (;;) {
+		wait_event(lo->lo_bh_wait, loop_active(lo));
+		if (!atomic_read(&lo->lo_pending)) {
+			int exiting = 0;
+			spin_lock_irq(&lo->lo_lock);
+			exiting = (lo->lo_state == LLOOP_RUNDOWN);
+			spin_unlock_irq(&lo->lo_lock);
+			if (exiting)
+				break;
+		}
+
+		bio = NULL;
+		count = loop_get_bio(lo, &bio);
+		if (!count) {
+			CWARN("lloop(minor: %d): missing bio\n", lo->lo_number);
+			continue;
+		}
+
+		total_count += count;
+		if (total_count < count) {     /* overflow */
+			total_count = count;
+			times = 1;
+		} else {
+			times++;
+		}
+		if ((times & 127) == 0) {
+			CDEBUG(D_INFO, "total: %lu, count: %lu, avg: %lu\n",
+			       total_count, times, total_count / times);
+		}
+
+		LASSERT(bio != NULL);
+		LASSERT(count <= atomic_read(&lo->lo_pending));
+		loop_handle_bio(lo, bio);
+		atomic_sub(count, &lo->lo_pending);
+	}
+	cl_env_put(env, &refcheck);
+
+out:
+	up(&lo->lo_sem);
+	return ret;
+}
+
+static int loop_set_fd(struct lloop_device *lo, struct file *unused,
+		       struct block_device *bdev, struct file *file)
+{
+	struct inode	 *inode;
+	struct address_space *mapping;
+	int		   lo_flags = 0;
+	int		   error;
+	loff_t		size;
+
+	if (!try_module_get(THIS_MODULE))
+		return -ENODEV;
+
+	error = -EBUSY;
+	if (lo->lo_state != LLOOP_UNBOUND)
+		goto out;
+
+	mapping = file->f_mapping;
+	inode = mapping->host;
+
+	error = -EINVAL;
+	if (!S_ISREG(inode->i_mode) || inode->i_sb->s_magic != LL_SUPER_MAGIC)
+		goto out;
+
+	if (!(file->f_mode & FMODE_WRITE))
+		lo_flags |= LO_FLAGS_READ_ONLY;
+
+	size = get_loop_size(lo, file);
+
+	if ((loff_t)(sector_t)size != size) {
+		error = -EFBIG;
+		goto out;
+	}
+
+	/* remove all pages in cache so as dirty pages not to be existent. */
+	truncate_inode_pages(mapping, 0);
+
+	set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
+
+	lo->lo_blocksize = PAGE_CACHE_SIZE;
+	lo->lo_device = bdev;
+	lo->lo_flags = lo_flags;
+	lo->lo_backing_file = file;
+	lo->lo_sizelimit = 0;
+	lo->old_gfp_mask = mapping_gfp_mask(mapping);
+	mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
+
+	lo->lo_bio = lo->lo_biotail = NULL;
+
+	/*
+	 * set queue make_request_fn, and add limits based on lower level
+	 * device
+	 */
+	blk_queue_make_request(lo->lo_queue, loop_make_request);
+	lo->lo_queue->queuedata = lo;
+
+	/* queue parameters */
+	CLASSERT(PAGE_CACHE_SIZE < (1 << (sizeof(unsigned short) * 8)));
+	blk_queue_logical_block_size(lo->lo_queue,
+				     (unsigned short)PAGE_CACHE_SIZE);
+	blk_queue_max_hw_sectors(lo->lo_queue,
+				 LLOOP_MAX_SEGMENTS << (PAGE_CACHE_SHIFT - 9));
+	blk_queue_max_segments(lo->lo_queue, LLOOP_MAX_SEGMENTS);
+
+	set_capacity(disks[lo->lo_number], size);
+	bd_set_size(bdev, size << 9);
+
+	set_blocksize(bdev, lo->lo_blocksize);
+
+	kthread_run(loop_thread, lo, "lloop%d", lo->lo_number);
+	down(&lo->lo_sem);
+	return 0;
+
+out:
+	/* This is safe: open() is still holding a reference. */
+	module_put(THIS_MODULE);
+	return error;
+}
+
+static int loop_clr_fd(struct lloop_device *lo, struct block_device *bdev,
+		       int count)
+{
+	struct file *filp = lo->lo_backing_file;
+	gfp_t gfp = lo->old_gfp_mask;
+
+	if (lo->lo_state != LLOOP_BOUND)
+		return -ENXIO;
+
+	if (lo->lo_refcnt > count)	/* we needed one fd for the ioctl */
+		return -EBUSY;
+
+	if (filp == NULL)
+		return -EINVAL;
+
+	spin_lock_irq(&lo->lo_lock);
+	lo->lo_state = LLOOP_RUNDOWN;
+	spin_unlock_irq(&lo->lo_lock);
+	wake_up(&lo->lo_bh_wait);
+
+	down(&lo->lo_sem);
+	lo->lo_backing_file = NULL;
+	lo->lo_device = NULL;
+	lo->lo_offset = 0;
+	lo->lo_sizelimit = 0;
+	lo->lo_flags = 0;
+	invalidate_bdev(bdev);
+	set_capacity(disks[lo->lo_number], 0);
+	bd_set_size(bdev, 0);
+	mapping_set_gfp_mask(filp->f_mapping, gfp);
+	lo->lo_state = LLOOP_UNBOUND;
+	fput(filp);
+	/* This is safe: open() is still holding a reference. */
+	module_put(THIS_MODULE);
+	return 0;
+}
+
+static int lo_open(struct block_device *bdev, fmode_t mode)
+{
+	struct lloop_device *lo = bdev->bd_disk->private_data;
+
+	mutex_lock(&lo->lo_ctl_mutex);
+	lo->lo_refcnt++;
+	mutex_unlock(&lo->lo_ctl_mutex);
+
+	return 0;
+}
+
+static void lo_release(struct gendisk *disk, fmode_t mode)
+{
+	struct lloop_device *lo = disk->private_data;
+
+	mutex_lock(&lo->lo_ctl_mutex);
+	--lo->lo_refcnt;
+	mutex_unlock(&lo->lo_ctl_mutex);
+}
+
+/* lloop device node's ioctl function. */
+static int lo_ioctl(struct block_device *bdev, fmode_t mode,
+		    unsigned int cmd, unsigned long arg)
+{
+	struct lloop_device *lo = bdev->bd_disk->private_data;
+	struct inode *inode = NULL;
+	int err = 0;
+
+	mutex_lock(&lloop_mutex);
+	switch (cmd) {
+	case LL_IOC_LLOOP_DETACH: {
+		err = loop_clr_fd(lo, bdev, 2);
+		if (err == 0)
+			blkdev_put(bdev, 0); /* grabbed in LLOOP_ATTACH */
+		break;
+	}
+
+	case LL_IOC_LLOOP_INFO: {
+		struct lu_fid fid;
+
+		if (lo->lo_backing_file == NULL) {
+			err = -ENOENT;
+			break;
+		}
+		if (inode == NULL)
+			inode = file_inode(lo->lo_backing_file);
+		if (lo->lo_state == LLOOP_BOUND)
+			fid = ll_i2info(inode)->lli_fid;
+		else
+			fid_zero(&fid);
+
+		if (copy_to_user((struct lu_fid *)arg, &fid, sizeof(fid)))
+			err = -EFAULT;
+		break;
+	}
+
+	default:
+		err = -EINVAL;
+		break;
+	}
+	mutex_unlock(&lloop_mutex);
+
+	return err;
+}
+
+static struct block_device_operations lo_fops = {
+	.owner =	THIS_MODULE,
+	.open =	 lo_open,
+	.release =      lo_release,
+	.ioctl =	lo_ioctl,
+};
+
+/* dynamic iocontrol callback.
+ * This callback is registered in lloop_init and will be called by
+ * ll_iocontrol_call.
+ *
+ * This is a llite regular file ioctl function. It takes the responsibility
+ * of attaching or detaching a file by a lloop's device number.
+ */
+static enum llioc_iter lloop_ioctl(struct inode *unused, struct file *file,
+				   unsigned int cmd, unsigned long arg,
+				   void *magic, int *rcp)
+{
+	struct lloop_device *lo = NULL;
+	struct block_device *bdev = NULL;
+	int err = 0;
+	dev_t dev;
+
+	if (magic != ll_iocontrol_magic)
+		return LLIOC_CONT;
+
+	if (disks == NULL) {
+		err = -ENODEV;
+		goto out1;
+	}
+
+	CWARN("Enter llop_ioctl\n");
+
+	mutex_lock(&lloop_mutex);
+	switch (cmd) {
+	case LL_IOC_LLOOP_ATTACH: {
+		struct lloop_device *lo_free = NULL;
+		int i;
+
+		for (i = 0; i < max_loop; i++, lo = NULL) {
+			lo = &loop_dev[i];
+			if (lo->lo_state == LLOOP_UNBOUND) {
+				if (!lo_free)
+					lo_free = lo;
+				continue;
+			}
+			if (file_inode(lo->lo_backing_file) == file_inode(file))
+				break;
+		}
+		if (lo || !lo_free) {
+			err = -EBUSY;
+			goto out;
+		}
+
+		lo = lo_free;
+		dev = MKDEV(lloop_major, lo->lo_number);
+
+		/* quit if the used pointer is writable */
+		if (put_user((long)old_encode_dev(dev), (long *)arg)) {
+			err = -EFAULT;
+			goto out;
+		}
+
+		bdev = blkdev_get_by_dev(dev, file->f_mode, NULL);
+		if (IS_ERR(bdev)) {
+			err = PTR_ERR(bdev);
+			goto out;
+		}
+
+		get_file(file);
+		err = loop_set_fd(lo, NULL, bdev, file);
+		if (err) {
+			fput(file);
+			blkdev_put(bdev, 0);
+		}
+
+		break;
+	}
+
+	case LL_IOC_LLOOP_DETACH_BYDEV: {
+		int minor;
+
+		dev = old_decode_dev(arg);
+		if (MAJOR(dev) != lloop_major) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		minor = MINOR(dev);
+		if (minor > max_loop - 1) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		lo = &loop_dev[minor];
+		if (lo->lo_state != LLOOP_BOUND) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		bdev = lo->lo_device;
+		err = loop_clr_fd(lo, bdev, 1);
+		if (err == 0)
+			blkdev_put(bdev, 0); /* grabbed in LLOOP_ATTACH */
+
+		break;
+	}
+
+	default:
+		err = -EINVAL;
+		break;
+	}
+
+out:
+	mutex_unlock(&lloop_mutex);
+out1:
+	if (rcp)
+		*rcp = err;
+	return LLIOC_STOP;
+}
+
+static int __init lloop_init(void)
+{
+	int	i;
+	unsigned int cmdlist[] = {
+		LL_IOC_LLOOP_ATTACH,
+		LL_IOC_LLOOP_DETACH_BYDEV,
+	};
+
+	if (max_loop < 1 || max_loop > 256) {
+		max_loop = MAX_LOOP_DEFAULT;
+		CWARN("lloop: invalid max_loop (must be between 1 and 256), using default (%u)\n",
+		      max_loop);
+	}
+
+	lloop_major = register_blkdev(0, "lloop");
+	if (lloop_major < 0)
+		return -EIO;
+
+	CDEBUG(D_CONFIG, "registered lloop major %d with %u minors\n",
+	       lloop_major, max_loop);
+
+	ll_iocontrol_magic = ll_iocontrol_register(lloop_ioctl, 2, cmdlist);
+	if (ll_iocontrol_magic == NULL)
+		goto out_mem1;
+
+	loop_dev = kcalloc(max_loop, sizeof(*loop_dev), GFP_KERNEL);
+	if (!loop_dev)
+		goto out_mem1;
+
+	disks = kcalloc(max_loop, sizeof(*disks), GFP_KERNEL);
+	if (!disks)
+		goto out_mem2;
+
+	for (i = 0; i < max_loop; i++) {
+		disks[i] = alloc_disk(1);
+		if (!disks[i])
+			goto out_mem3;
+	}
+
+	mutex_init(&lloop_mutex);
+
+	for (i = 0; i < max_loop; i++) {
+		struct lloop_device *lo = &loop_dev[i];
+		struct gendisk *disk = disks[i];
+
+		lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
+		if (!lo->lo_queue)
+			goto out_mem4;
+
+		mutex_init(&lo->lo_ctl_mutex);
+		sema_init(&lo->lo_sem, 0);
+		init_waitqueue_head(&lo->lo_bh_wait);
+		lo->lo_number = i;
+		spin_lock_init(&lo->lo_lock);
+		disk->major = lloop_major;
+		disk->first_minor = i;
+		disk->fops = &lo_fops;
+		sprintf(disk->disk_name, "lloop%d", i);
+		disk->private_data = lo;
+		disk->queue = lo->lo_queue;
+	}
+
+	/* We cannot fail after we call this, so another loop!*/
+	for (i = 0; i < max_loop; i++)
+		add_disk(disks[i]);
+	return 0;
+
+out_mem4:
+	while (i--)
+		blk_cleanup_queue(loop_dev[i].lo_queue);
+	i = max_loop;
+out_mem3:
+	while (i--)
+		put_disk(disks[i]);
+	OBD_FREE(disks, max_loop * sizeof(*disks));
+out_mem2:
+	OBD_FREE(loop_dev, max_loop * sizeof(*loop_dev));
+out_mem1:
+	unregister_blkdev(lloop_major, "lloop");
+	ll_iocontrol_unregister(ll_iocontrol_magic);
+	CERROR("lloop: ran out of memory\n");
+	return -ENOMEM;
+}
+
+static void lloop_exit(void)
+{
+	int i;
+
+	ll_iocontrol_unregister(ll_iocontrol_magic);
+	for (i = 0; i < max_loop; i++) {
+		del_gendisk(disks[i]);
+		blk_cleanup_queue(loop_dev[i].lo_queue);
+		put_disk(disks[i]);
+	}
+
+	unregister_blkdev(lloop_major, "lloop");
+
+	OBD_FREE(disks, max_loop * sizeof(*disks));
+	OBD_FREE(loop_dev, max_loop * sizeof(*loop_dev));
+}
+
+module_init(lloop_init);
+module_exit(lloop_exit);
+
+module_param(max_loop, int, 0444);
+MODULE_PARM_DESC(max_loop, "maximum of lloop_device");
+MODULE_AUTHOR("Sun Microsystems, Inc. <http://www.lustre.org/>");
+MODULE_DESCRIPTION("Lustre virtual block device");
+MODULE_LICENSE("GPL");