Initial import

1 files changed, 1748 insertions, 0 deletions

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
new file mode 100644
index 000000000..88e4c7f24
--- /dev/null
+++ b/drivers/md/dm-raid.c
@@ -0,0 +1,1748 @@
+/*
+ * Copyright (C) 2010-2011 Neil Brown
+ * Copyright (C) 2010-2014 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+
+#include "md.h"
+#include "raid1.h"
+#include "raid5.h"
+#include "raid10.h"
+#include "bitmap.h"
+
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "raid"
+
+static bool devices_handle_discard_safely = false;
+
+/*
+ * The following flags are used by dm-raid.c to set up the array state.
+ * They must be cleared before md_run is called.
+ */
+#define FirstUse 10             /* rdev flag */
+
+struct raid_dev {
+	/*
+	 * Two DM devices, one to hold metadata and one to hold the
+	 * actual data/parity.  The reason for this is to not confuse
+	 * ti->len and give more flexibility in altering size and
+	 * characteristics.
+	 *
+	 * While it is possible for this device to be associated
+	 * with a different physical device than the data_dev, it
+	 * is intended for it to be the same.
+	 *    |--------- Physical Device ---------|
+	 *    |- meta_dev -|------ data_dev ------|
+	 */
+	struct dm_dev *meta_dev;
+	struct dm_dev *data_dev;
+	struct md_rdev rdev;
+};
+
+/*
+ * Flags for rs->print_flags field.
+ */
+#define DMPF_SYNC              0x1
+#define DMPF_NOSYNC            0x2
+#define DMPF_REBUILD           0x4
+#define DMPF_DAEMON_SLEEP      0x8
+#define DMPF_MIN_RECOVERY_RATE 0x10
+#define DMPF_MAX_RECOVERY_RATE 0x20
+#define DMPF_MAX_WRITE_BEHIND  0x40
+#define DMPF_STRIPE_CACHE      0x80
+#define DMPF_REGION_SIZE       0x100
+#define DMPF_RAID10_COPIES     0x200
+#define DMPF_RAID10_FORMAT     0x400
+
+struct raid_set {
+	struct dm_target *ti;
+
+	uint32_t bitmap_loaded;
+	uint32_t print_flags;
+
+	struct mddev md;
+	struct raid_type *raid_type;
+	struct dm_target_callbacks callbacks;
+
+	struct raid_dev dev[0];
+};
+
+/* Supported raid types and properties. */
+static struct raid_type {
+	const char *name;		/* RAID algorithm. */
+	const char *descr;		/* Descriptor text for logging. */
+	const unsigned parity_devs;	/* # of parity devices. */
+	const unsigned minimal_devs;	/* minimal # of devices in set. */
+	const unsigned level;		/* RAID level. */
+	const unsigned algorithm;	/* RAID algorithm. */
+} raid_types[] = {
+	{"raid1",    "RAID1 (mirroring)",               0, 2, 1, 0 /* NONE */},
+	{"raid10",   "RAID10 (striped mirrors)",        0, 2, 10, UINT_MAX /* Varies */},
+	{"raid4",    "RAID4 (dedicated parity disk)",	1, 2, 5, ALGORITHM_PARITY_0},
+	{"raid5_la", "RAID5 (left asymmetric)",		1, 2, 5, ALGORITHM_LEFT_ASYMMETRIC},
+	{"raid5_ra", "RAID5 (right asymmetric)",	1, 2, 5, ALGORITHM_RIGHT_ASYMMETRIC},
+	{"raid5_ls", "RAID5 (left symmetric)",		1, 2, 5, ALGORITHM_LEFT_SYMMETRIC},
+	{"raid5_rs", "RAID5 (right symmetric)",		1, 2, 5, ALGORITHM_RIGHT_SYMMETRIC},
+	{"raid6_zr", "RAID6 (zero restart)",		2, 4, 6, ALGORITHM_ROTATING_ZERO_RESTART},
+	{"raid6_nr", "RAID6 (N restart)",		2, 4, 6, ALGORITHM_ROTATING_N_RESTART},
+	{"raid6_nc", "RAID6 (N continue)",		2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE}
+};
+
+static char *raid10_md_layout_to_format(int layout)
+{
+	/*
+	 * Bit 16 and 17 stand for "offset" and "use_far_sets"
+	 * Refer to MD's raid10.c for details
+	 */
+	if ((layout & 0x10000) && (layout & 0x20000))
+		return "offset";
+
+	if ((layout & 0xFF) > 1)
+		return "near";
+
+	return "far";
+}
+
+static unsigned raid10_md_layout_to_copies(int layout)
+{
+	if ((layout & 0xFF) > 1)
+		return layout & 0xFF;
+	return (layout >> 8) & 0xFF;
+}
+
+static int raid10_format_to_md_layout(char *format, unsigned copies)
+{
+	unsigned n = 1, f = 1;
+
+	if (!strcmp("near", format))
+		n = copies;
+	else
+		f = copies;
+
+	if (!strcmp("offset", format))
+		return 0x30000 | (f << 8) | n;
+
+	if (!strcmp("far", format))
+		return 0x20000 | (f << 8) | n;
+
+	return (f << 8) | n;
+}
+
+static struct raid_type *get_raid_type(char *name)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(raid_types); i++)
+		if (!strcmp(raid_types[i].name, name))
+			return &raid_types[i];
+
+	return NULL;
+}
+
+static struct raid_set *context_alloc(struct dm_target *ti, struct raid_type *raid_type, unsigned raid_devs)
+{
+	unsigned i;
+	struct raid_set *rs;
+
+	if (raid_devs <= raid_type->parity_devs) {
+		ti->error = "Insufficient number of devices";
+		return ERR_PTR(-EINVAL);
+	}
+
+	rs = kzalloc(sizeof(*rs) + raid_devs * sizeof(rs->dev[0]), GFP_KERNEL);
+	if (!rs) {
+		ti->error = "Cannot allocate raid context";
+		return ERR_PTR(-ENOMEM);
+	}
+
+	mddev_init(&rs->md);
+
+	rs->ti = ti;
+	rs->raid_type = raid_type;
+	rs->md.raid_disks = raid_devs;
+	rs->md.level = raid_type->level;
+	rs->md.new_level = rs->md.level;
+	rs->md.layout = raid_type->algorithm;
+	rs->md.new_layout = rs->md.layout;
+	rs->md.delta_disks = 0;
+	rs->md.recovery_cp = 0;
+
+	for (i = 0; i < raid_devs; i++)
+		md_rdev_init(&rs->dev[i].rdev);
+
+	/*
+	 * Remaining items to be initialized by further RAID params:
+	 *  rs->md.persistent
+	 *  rs->md.external
+	 *  rs->md.chunk_sectors
+	 *  rs->md.new_chunk_sectors
+	 *  rs->md.dev_sectors
+	 */
+
+	return rs;
+}
+
+static void context_free(struct raid_set *rs)
+{
+	int i;
+
+	for (i = 0; i < rs->md.raid_disks; i++) {
+		if (rs->dev[i].meta_dev)
+			dm_put_device(rs->ti, rs->dev[i].meta_dev);
+		md_rdev_clear(&rs->dev[i].rdev);
+		if (rs->dev[i].data_dev)
+			dm_put_device(rs->ti, rs->dev[i].data_dev);
+	}
+
+	kfree(rs);
+}
+
+/*
+ * For every device we have two words
+ *  <meta_dev>: meta device name or '-' if missing
+ *  <data_dev>: data device name or '-' if missing
+ *
+ * The following are permitted:
+ *    - -
+ *    - <data_dev>
+ *    <meta_dev> <data_dev>
+ *
+ * The following is not allowed:
+ *    <meta_dev> -
+ *
+ * This code parses those words.  If there is a failure,
+ * the caller must use context_free to unwind the operations.
+ */
+static int dev_parms(struct raid_set *rs, char **argv)
+{
+	int i;
+	int rebuild = 0;
+	int metadata_available = 0;
+	int ret = 0;
+
+	for (i = 0; i < rs->md.raid_disks; i++, argv += 2) {
+		rs->dev[i].rdev.raid_disk = i;
+
+		rs->dev[i].meta_dev = NULL;
+		rs->dev[i].data_dev = NULL;
+
+		/*
+		 * There are no offsets, since there is a separate device
+		 * for data and metadata.
+		 */
+		rs->dev[i].rdev.data_offset = 0;
+		rs->dev[i].rdev.mddev = &rs->md;
+
+		if (strcmp(argv[0], "-")) {
+			ret = dm_get_device(rs->ti, argv[0],
+					    dm_table_get_mode(rs->ti->table),
+					    &rs->dev[i].meta_dev);
+			rs->ti->error = "RAID metadata device lookup failure";
+			if (ret)
+				return ret;
+
+			rs->dev[i].rdev.sb_page = alloc_page(GFP_KERNEL);
+			if (!rs->dev[i].rdev.sb_page)
+				return -ENOMEM;
+		}
+
+		if (!strcmp(argv[1], "-")) {
+			if (!test_bit(In_sync, &rs->dev[i].rdev.flags) &&
+			    (!rs->dev[i].rdev.recovery_offset)) {
+				rs->ti->error = "Drive designated for rebuild not specified";
+				return -EINVAL;
+			}
+
+			rs->ti->error = "No data device supplied with metadata device";
+			if (rs->dev[i].meta_dev)
+				return -EINVAL;
+
+			continue;
+		}
+
+		ret = dm_get_device(rs->ti, argv[1],
+				    dm_table_get_mode(rs->ti->table),
+				    &rs->dev[i].data_dev);
+		if (ret) {
+			rs->ti->error = "RAID device lookup failure";
+			return ret;
+		}
+
+		if (rs->dev[i].meta_dev) {
+			metadata_available = 1;
+			rs->dev[i].rdev.meta_bdev = rs->dev[i].meta_dev->bdev;
+		}
+		rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev;
+		list_add(&rs->dev[i].rdev.same_set, &rs->md.disks);
+		if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
+			rebuild++;
+	}
+
+	if (metadata_available) {
+		rs->md.external = 0;
+		rs->md.persistent = 1;
+		rs->md.major_version = 2;
+	} else if (rebuild && !rs->md.recovery_cp) {
+		/*
+		 * Without metadata, we will not be able to tell if the array
+		 * is in-sync or not - we must assume it is not.  Therefore,
+		 * it is impossible to rebuild a drive.
+		 *
+		 * Even if there is metadata, the on-disk information may
+		 * indicate that the array is not in-sync and it will then
+		 * fail at that time.
+		 *
+		 * User could specify 'nosync' option if desperate.
+		 */
+		DMERR("Unable to rebuild drive while array is not in-sync");
+		rs->ti->error = "RAID device lookup failure";
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * validate_region_size
+ * @rs
+ * @region_size:  region size in sectors.  If 0, pick a size (4MiB default).
+ *
+ * Set rs->md.bitmap_info.chunksize (which really refers to 'region size').
+ * Ensure that (ti->len/region_size < 2^21) - required by MD bitmap.
+ *
+ * Returns: 0 on success, -EINVAL on failure.
+ */
+static int validate_region_size(struct raid_set *rs, unsigned long region_size)
+{
+	unsigned long min_region_size = rs->ti->len / (1 << 21);
+
+	if (!region_size) {
+		/*
+		 * Choose a reasonable default.  All figures in sectors.
+		 */
+		if (min_region_size > (1 << 13)) {
+			/* If not a power of 2, make it the next power of 2 */
+			if (min_region_size & (min_region_size - 1))
+				region_size = 1 << fls(region_size);
+			DMINFO("Choosing default region size of %lu sectors",
+			       region_size);
+		} else {
+			DMINFO("Choosing default region size of 4MiB");
+			region_size = 1 << 13; /* sectors */
+		}
+	} else {
+		/*
+		 * Validate user-supplied value.
+		 */
+		if (region_size > rs->ti->len) {
+			rs->ti->error = "Supplied region size is too large";
+			return -EINVAL;
+		}
+
+		if (region_size < min_region_size) {
+			DMERR("Supplied region_size (%lu sectors) below minimum (%lu)",
+			      region_size, min_region_size);
+			rs->ti->error = "Supplied region size is too small";
+			return -EINVAL;
+		}
+
+		if (!is_power_of_2(region_size)) {
+			rs->ti->error = "Region size is not a power of 2";
+			return -EINVAL;
+		}
+
+		if (region_size < rs->md.chunk_sectors) {
+			rs->ti->error = "Region size is smaller than the chunk size";
+			return -EINVAL;
+		}
+	}
+
+	/*
+	 * Convert sectors to bytes.
+	 */
+	rs->md.bitmap_info.chunksize = (region_size << 9);
+
+	return 0;
+}
+
+/*
+ * validate_raid_redundancy
+ * @rs
+ *
+ * Determine if there are enough devices in the array that haven't
+ * failed (or are being rebuilt) to form a usable array.
+ *
+ * Returns: 0 on success, -EINVAL on failure.
+ */
+static int validate_raid_redundancy(struct raid_set *rs)
+{
+	unsigned i, rebuild_cnt = 0;
+	unsigned rebuilds_per_group = 0, copies, d;
+	unsigned group_size, last_group_start;
+
+	for (i = 0; i < rs->md.raid_disks; i++)
+		if (!test_bit(In_sync, &rs->dev[i].rdev.flags) ||
+		    !rs->dev[i].rdev.sb_page)
+			rebuild_cnt++;
+
+	switch (rs->raid_type->level) {
+	case 1:
+		if (rebuild_cnt >= rs->md.raid_disks)
+			goto too_many;
+		break;
+	case 4:
+	case 5:
+	case 6:
+		if (rebuild_cnt > rs->raid_type->parity_devs)
+			goto too_many;
+		break;
+	case 10:
+		copies = raid10_md_layout_to_copies(rs->md.layout);
+		if (rebuild_cnt < copies)
+			break;
+
+		/*
+		 * It is possible to have a higher rebuild count for RAID10,
+		 * as long as the failed devices occur in different mirror
+		 * groups (i.e. different stripes).
+		 *
+		 * When checking "near" format, make sure no adjacent devices
+		 * have failed beyond what can be handled.  In addition to the
+		 * simple case where the number of devices is a multiple of the
+		 * number of copies, we must also handle cases where the number
+		 * of devices is not a multiple of the number of copies.
+		 * E.g.    dev1 dev2 dev3 dev4 dev5
+		 *          A    A    B    B    C
+		 *          C    D    D    E    E
+		 */
+		if (!strcmp("near", raid10_md_layout_to_format(rs->md.layout))) {
+			for (i = 0; i < rs->md.raid_disks * copies; i++) {
+				if (!(i % copies))
+					rebuilds_per_group = 0;
+				d = i % rs->md.raid_disks;
+				if ((!rs->dev[d].rdev.sb_page ||
+				     !test_bit(In_sync, &rs->dev[d].rdev.flags)) &&
+				    (++rebuilds_per_group >= copies))
+					goto too_many;
+			}
+			break;
+		}
+
+		/*
+		 * When checking "far" and "offset" formats, we need to ensure
+		 * that the device that holds its copy is not also dead or
+		 * being rebuilt.  (Note that "far" and "offset" formats only
+		 * support two copies right now.  These formats also only ever
+		 * use the 'use_far_sets' variant.)
+		 *
+		 * This check is somewhat complicated by the need to account
+		 * for arrays that are not a multiple of (far) copies.  This
+		 * results in the need to treat the last (potentially larger)
+		 * set differently.
+		 */
+		group_size = (rs->md.raid_disks / copies);
+		last_group_start = (rs->md.raid_disks / group_size) - 1;
+		last_group_start *= group_size;
+		for (i = 0; i < rs->md.raid_disks; i++) {
+			if (!(i % copies) && !(i > last_group_start))
+				rebuilds_per_group = 0;
+			if ((!rs->dev[i].rdev.sb_page ||
+			     !test_bit(In_sync, &rs->dev[i].rdev.flags)) &&
+			    (++rebuilds_per_group >= copies))
+					goto too_many;
+		}
+		break;
+	default:
+		if (rebuild_cnt)
+			return -EINVAL;
+	}
+
+	return 0;
+
+too_many:
+	return -EINVAL;
+}
+
+/*
+ * Possible arguments are...
+ *	<chunk_size> [optional_args]
+ *
+ * Argument definitions
+ *    <chunk_size>			The number of sectors per disk that
+ *                                      will form the "stripe"
+ *    [[no]sync]			Force or prevent recovery of the
+ *                                      entire array
+ *    [devices_handle_discard_safely]	Allow discards on RAID4/5/6; useful if RAID
+ *					member device(s) properly support TRIM/UNMAP
+ *    [rebuild <idx>]			Rebuild the drive indicated by the index
+ *    [daemon_sleep <ms>]		Time between bitmap daemon work to
+ *                                      clear bits
+ *    [min_recovery_rate <kB/sec/disk>]	Throttle RAID initialization
+ *    [max_recovery_rate <kB/sec/disk>]	Throttle RAID initialization
+ *    [write_mostly <idx>]		Indicate a write mostly drive via index
+ *    [max_write_behind <sectors>]	See '-write-behind=' (man mdadm)
+ *    [stripe_cache <sectors>]		Stripe cache size for higher RAIDs
+ *    [region_size <sectors>]           Defines granularity of bitmap
+ *
+ * RAID10-only options:
+ *    [raid10_copies <# copies>]        Number of copies.  (Default: 2)
+ *    [raid10_format <near|far|offset>] Layout algorithm.  (Default: near)
+ */
+static int parse_raid_params(struct raid_set *rs, char **argv,
+			     unsigned num_raid_params)
+{
+	char *raid10_format = "near";
+	unsigned raid10_copies = 2;
+	unsigned i;
+	unsigned long value, region_size = 0;
+	sector_t sectors_per_dev = rs->ti->len;
+	sector_t max_io_len;
+	char *key;
+
+	/*
+	 * First, parse the in-order required arguments
+	 * "chunk_size" is the only argument of this type.
+	 */
+	if ((kstrtoul(argv[0], 10, &value) < 0)) {
+		rs->ti->error = "Bad chunk size";
+		return -EINVAL;
+	} else if (rs->raid_type->level == 1) {
+		if (value)
+			DMERR("Ignoring chunk size parameter for RAID 1");
+		value = 0;
+	} else if (!is_power_of_2(value)) {
+		rs->ti->error = "Chunk size must be a power of 2";
+		return -EINVAL;
+	} else if (value < 8) {
+		rs->ti->error = "Chunk size value is too small";
+		return -EINVAL;
+	}
+
+	rs->md.new_chunk_sectors = rs->md.chunk_sectors = value;
+	argv++;
+	num_raid_params--;
+
+	/*
+	 * We set each individual device as In_sync with a completed
+	 * 'recovery_offset'.  If there has been a device failure or
+	 * replacement then one of the following cases applies:
+	 *
+	 *   1) User specifies 'rebuild'.
+	 *      - Device is reset when param is read.
+	 *   2) A new device is supplied.
+	 *      - No matching superblock found, resets device.
+	 *   3) Device failure was transient and returns on reload.
+	 *      - Failure noticed, resets device for bitmap replay.
+	 *   4) Device hadn't completed recovery after previous failure.
+	 *      - Superblock is read and overrides recovery_offset.
+	 *
+	 * What is found in the superblocks of the devices is always
+	 * authoritative, unless 'rebuild' or '[no]sync' was specified.
+	 */
+	for (i = 0; i < rs->md.raid_disks; i++) {
+		set_bit(In_sync, &rs->dev[i].rdev.flags);
+		rs->dev[i].rdev.recovery_offset = MaxSector;
+	}
+
+	/*
+	 * Second, parse the unordered optional arguments
+	 */
+	for (i = 0; i < num_raid_params; i++) {
+		if (!strcasecmp(argv[i], "nosync")) {
+			rs->md.recovery_cp = MaxSector;
+			rs->print_flags |= DMPF_NOSYNC;
+			continue;
+		}
+		if (!strcasecmp(argv[i], "sync")) {
+			rs->md.recovery_cp = 0;
+			rs->print_flags |= DMPF_SYNC;
+			continue;
+		}
+
+		/* The rest of the optional arguments come in key/value pairs */
+		if ((i + 1) >= num_raid_params) {
+			rs->ti->error = "Wrong number of raid parameters given";
+			return -EINVAL;
+		}
+
+		key = argv[i++];
+
+		/* Parameters that take a string value are checked here. */
+		if (!strcasecmp(key, "raid10_format")) {
+			if (rs->raid_type->level != 10) {
+				rs->ti->error = "'raid10_format' is an invalid parameter for this RAID type";
+				return -EINVAL;
+			}
+			if (strcmp("near", argv[i]) &&
+			    strcmp("far", argv[i]) &&
+			    strcmp("offset", argv[i])) {
+				rs->ti->error = "Invalid 'raid10_format' value given";
+				return -EINVAL;
+			}
+			raid10_format = argv[i];
+			rs->print_flags |= DMPF_RAID10_FORMAT;
+			continue;
+		}
+
+		if (kstrtoul(argv[i], 10, &value) < 0) {
+			rs->ti->error = "Bad numerical argument given in raid params";
+			return -EINVAL;
+		}
+
+		/* Parameters that take a numeric value are checked here */
+		if (!strcasecmp(key, "rebuild")) {
+			if (value >= rs->md.raid_disks) {
+				rs->ti->error = "Invalid rebuild index given";
+				return -EINVAL;
+			}
+			clear_bit(In_sync, &rs->dev[value].rdev.flags);
+			rs->dev[value].rdev.recovery_offset = 0;
+			rs->print_flags |= DMPF_REBUILD;
+		} else if (!strcasecmp(key, "write_mostly")) {
+			if (rs->raid_type->level != 1) {
+				rs->ti->error = "write_mostly option is only valid for RAID1";
+				return -EINVAL;
+			}
+			if (value >= rs->md.raid_disks) {
+				rs->ti->error = "Invalid write_mostly drive index given";
+				return -EINVAL;
+			}
+			set_bit(WriteMostly, &rs->dev[value].rdev.flags);
+		} else if (!strcasecmp(key, "max_write_behind")) {
+			if (rs->raid_type->level != 1) {
+				rs->ti->error = "max_write_behind option is only valid for RAID1";
+				return -EINVAL;
+			}
+			rs->print_flags |= DMPF_MAX_WRITE_BEHIND;
+
+			/*
+			 * In device-mapper, we specify things in sectors, but
+			 * MD records this value in kB
+			 */
+			value /= 2;
+			if (value > COUNTER_MAX) {
+				rs->ti->error = "Max write-behind limit out of range";
+				return -EINVAL;
+			}
+			rs->md.bitmap_info.max_write_behind = value;
+		} else if (!strcasecmp(key, "daemon_sleep")) {
+			rs->print_flags |= DMPF_DAEMON_SLEEP;
+			if (!value || (value > MAX_SCHEDULE_TIMEOUT)) {
+				rs->ti->error = "daemon sleep period out of range";
+				return -EINVAL;
+			}
+			rs->md.bitmap_info.daemon_sleep = value;
+		} else if (!strcasecmp(key, "stripe_cache")) {
+			rs->print_flags |= DMPF_STRIPE_CACHE;
+
+			/*
+			 * In device-mapper, we specify things in sectors, but
+			 * MD records this value in kB
+			 */
+			value /= 2;
+
+			if ((rs->raid_type->level != 5) &&
+			    (rs->raid_type->level != 6)) {
+				rs->ti->error = "Inappropriate argument: stripe_cache";
+				return -EINVAL;
+			}
+			if (raid5_set_cache_size(&rs->md, (int)value)) {
+				rs->ti->error = "Bad stripe_cache size";
+				return -EINVAL;
+			}
+		} else if (!strcasecmp(key, "min_recovery_rate")) {
+			rs->print_flags |= DMPF_MIN_RECOVERY_RATE;
+			if (value > INT_MAX) {
+				rs->ti->error = "min_recovery_rate out of range";
+				return -EINVAL;
+			}
+			rs->md.sync_speed_min = (int)value;
+		} else if (!strcasecmp(key, "max_recovery_rate")) {
+			rs->print_flags |= DMPF_MAX_RECOVERY_RATE;
+			if (value > INT_MAX) {
+				rs->ti->error = "max_recovery_rate out of range";
+				return -EINVAL;
+			}
+			rs->md.sync_speed_max = (int)value;
+		} else if (!strcasecmp(key, "region_size")) {
+			rs->print_flags |= DMPF_REGION_SIZE;
+			region_size = value;
+		} else if (!strcasecmp(key, "raid10_copies") &&
+			   (rs->raid_type->level == 10)) {
+			if ((value < 2) || (value > 0xFF)) {
+				rs->ti->error = "Bad value for 'raid10_copies'";
+				return -EINVAL;
+			}
+			rs->print_flags |= DMPF_RAID10_COPIES;
+			raid10_copies = value;
+		} else {
+			DMERR("Unable to parse RAID parameter: %s", key);
+			rs->ti->error = "Unable to parse RAID parameters";
+			return -EINVAL;
+		}
+	}
+
+	if (validate_region_size(rs, region_size))
+		return -EINVAL;
+
+	if (rs->md.chunk_sectors)
+		max_io_len = rs->md.chunk_sectors;
+	else
+		max_io_len = region_size;
+
+	if (dm_set_target_max_io_len(rs->ti, max_io_len))
+		return -EINVAL;
+
+	if (rs->raid_type->level == 10) {
+		if (raid10_copies > rs->md.raid_disks) {
+			rs->ti->error = "Not enough devices to satisfy specification";
+			return -EINVAL;
+		}
+
+		/*
+		 * If the format is not "near", we only support
+		 * two copies at the moment.
+		 */
+		if (strcmp("near", raid10_format) && (raid10_copies > 2)) {
+			rs->ti->error = "Too many copies for given RAID10 format.";
+			return -EINVAL;
+		}
+
+		/* (Len * #mirrors) / #devices */
+		sectors_per_dev = rs->ti->len * raid10_copies;
+		sector_div(sectors_per_dev, rs->md.raid_disks);
+
+		rs->md.layout = raid10_format_to_md_layout(raid10_format,
+							   raid10_copies);
+		rs->md.new_layout = rs->md.layout;
+	} else if ((rs->raid_type->level > 1) &&
+		   sector_div(sectors_per_dev,
+			      (rs->md.raid_disks - rs->raid_type->parity_devs))) {
+		rs->ti->error = "Target length not divisible by number of data devices";
+		return -EINVAL;
+	}
+	rs->md.dev_sectors = sectors_per_dev;
+
+	/* Assume there are no metadata devices until the drives are parsed */
+	rs->md.persistent = 0;
+	rs->md.external = 1;
+
+	return 0;
+}
+
+static void do_table_event(struct work_struct *ws)
+{
+	struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);
+
+	dm_table_event(rs->ti->table);
+}
+
+static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
+{
+	struct raid_set *rs = container_of(cb, struct raid_set, callbacks);
+
+	return mddev_congested(&rs->md, bits);
+}
+
+/*
+ * This structure is never routinely used by userspace, unlike md superblocks.
+ * Devices with this superblock should only ever be accessed via device-mapper.
+ */
+#define DM_RAID_MAGIC 0x64526D44
+struct dm_raid_superblock {
+	__le32 magic;		/* "DmRd" */
+	__le32 features;	/* Used to indicate possible future changes */
+
+	__le32 num_devices;	/* Number of devices in this array. (Max 64) */
+	__le32 array_position;	/* The position of this drive in the array */
+
+	__le64 events;		/* Incremented by md when superblock updated */
+	__le64 failed_devices;	/* Bit field of devices to indicate failures */
+
+	/*
+	 * This offset tracks the progress of the repair or replacement of
+	 * an individual drive.
+	 */
+	__le64 disk_recovery_offset;
+
+	/*
+	 * This offset tracks the progress of the initial array
+	 * synchronisation/parity calculation.
+	 */
+	__le64 array_resync_offset;
+
+	/*
+	 * RAID characteristics
+	 */
+	__le32 level;
+	__le32 layout;
+	__le32 stripe_sectors;
+
+	/* Remainder of a logical block is zero-filled when writing (see super_sync()). */
+} __packed;
+
+static int read_disk_sb(struct md_rdev *rdev, int size)
+{
+	BUG_ON(!rdev->sb_page);
+
+	if (rdev->sb_loaded)
+		return 0;
+
+	if (!sync_page_io(rdev, 0, size, rdev->sb_page, READ, 1)) {
+		DMERR("Failed to read superblock of device at position %d",
+		      rdev->raid_disk);
+		md_error(rdev->mddev, rdev);
+		return -EINVAL;
+	}
+
+	rdev->sb_loaded = 1;
+
+	return 0;
+}
+
+static void super_sync(struct mddev *mddev, struct md_rdev *rdev)
+{
+	int i;
+	uint64_t failed_devices;
+	struct dm_raid_superblock *sb;
+	struct raid_set *rs = container_of(mddev, struct raid_set, md);
+
+	sb = page_address(rdev->sb_page);
+	failed_devices = le64_to_cpu(sb->failed_devices);
+
+	for (i = 0; i < mddev->raid_disks; i++)
+		if (!rs->dev[i].data_dev ||
+		    test_bit(Faulty, &(rs->dev[i].rdev.flags)))
+			failed_devices |= (1ULL << i);
+
+	memset(sb + 1, 0, rdev->sb_size - sizeof(*sb));
+
+	sb->magic = cpu_to_le32(DM_RAID_MAGIC);
+	sb->features = cpu_to_le32(0);	/* No features yet */
+
+	sb->num_devices = cpu_to_le32(mddev->raid_disks);
+	sb->array_position = cpu_to_le32(rdev->raid_disk);
+
+	sb->events = cpu_to_le64(mddev->events);
+	sb->failed_devices = cpu_to_le64(failed_devices);
+
+	sb->disk_recovery_offset = cpu_to_le64(rdev->recovery_offset);
+	sb->array_resync_offset = cpu_to_le64(mddev->recovery_cp);
+
+	sb->level = cpu_to_le32(mddev->level);
+	sb->layout = cpu_to_le32(mddev->layout);
+	sb->stripe_sectors = cpu_to_le32(mddev->chunk_sectors);
+}
+
+/*
+ * super_load
+ *
+ * This function creates a superblock if one is not found on the device
+ * and will decide which superblock to use if there's a choice.
+ *
+ * Return: 1 if use rdev, 0 if use refdev, -Exxx otherwise
+ */
+static int super_load(struct md_rdev *rdev, struct md_rdev *refdev)
+{
+	int ret;
+	struct dm_raid_superblock *sb;
+	struct dm_raid_superblock *refsb;
+	uint64_t events_sb, events_refsb;
+
+	rdev->sb_start = 0;
+	rdev->sb_size = bdev_logical_block_size(rdev->meta_bdev);
+	if (rdev->sb_size < sizeof(*sb) || rdev->sb_size > PAGE_SIZE) {
+		DMERR("superblock size of a logical block is no longer valid");
+		return -EINVAL;
+	}
+
+	ret = read_disk_sb(rdev, rdev->sb_size);
+	if (ret)
+		return ret;
+
+	sb = page_address(rdev->sb_page);
+
+	/*
+	 * Two cases that we want to write new superblocks and rebuild:
+	 * 1) New device (no matching magic number)
+	 * 2) Device specified for rebuild (!In_sync w/ offset == 0)
+	 */
+	if ((sb->magic != cpu_to_le32(DM_RAID_MAGIC)) ||
+	    (!test_bit(In_sync, &rdev->flags) && !rdev->recovery_offset)) {
+		super_sync(rdev->mddev, rdev);
+
+		set_bit(FirstUse, &rdev->flags);
+
+		/* Force writing of superblocks to disk */
+		set_bit(MD_CHANGE_DEVS, &rdev->mddev->flags);
+
+		/* Any superblock is better than none, choose that if given */
+		return refdev ? 0 : 1;
+	}
+
+	if (!refdev)
+		return 1;
+
+	events_sb = le64_to_cpu(sb->events);
+
+	refsb = page_address(refdev->sb_page);
+	events_refsb = le64_to_cpu(refsb->events);
+
+	return (events_sb > events_refsb) ? 1 : 0;
+}
+
+static int super_init_validation(struct mddev *mddev, struct md_rdev *rdev)
+{
+	int role;
+	struct raid_set *rs = container_of(mddev, struct raid_set, md);
+	uint64_t events_sb;
+	uint64_t failed_devices;
+	struct dm_raid_superblock *sb;
+	uint32_t new_devs = 0;
+	uint32_t rebuilds = 0;
+	struct md_rdev *r;
+	struct dm_raid_superblock *sb2;
+
+	sb = page_address(rdev->sb_page);
+	events_sb = le64_to_cpu(sb->events);
+	failed_devices = le64_to_cpu(sb->failed_devices);
+
+	/*
+	 * Initialise to 1 if this is a new superblock.
+	 */
+	mddev->events = events_sb ? : 1;
+
+	/*
+	 * Reshaping is not currently allowed
+	 */
+	if (le32_to_cpu(sb->level) != mddev->level) {
+		DMERR("Reshaping arrays not yet supported. (RAID level change)");
+		return -EINVAL;
+	}
+	if (le32_to_cpu(sb->layout) != mddev->layout) {
+		DMERR("Reshaping arrays not yet supported. (RAID layout change)");
+		DMERR("  0x%X vs 0x%X", le32_to_cpu(sb->layout), mddev->layout);
+		DMERR("  Old layout: %s w/ %d copies",
+		      raid10_md_layout_to_format(le32_to_cpu(sb->layout)),
+		      raid10_md_layout_to_copies(le32_to_cpu(sb->layout)));
+		DMERR("  New layout: %s w/ %d copies",
+		      raid10_md_layout_to_format(mddev->layout),
+		      raid10_md_layout_to_copies(mddev->layout));
+		return -EINVAL;
+	}
+	if (le32_to_cpu(sb->stripe_sectors) != mddev->chunk_sectors) {
+		DMERR("Reshaping arrays not yet supported. (stripe sectors change)");
+		return -EINVAL;
+	}
+
+	/* We can only change the number of devices in RAID1 right now */
+	if ((rs->raid_type->level != 1) &&
+	    (le32_to_cpu(sb->num_devices) != mddev->raid_disks)) {
+		DMERR("Reshaping arrays not yet supported. (device count change)");
+		return -EINVAL;
+	}
+
+	if (!(rs->print_flags & (DMPF_SYNC | DMPF_NOSYNC)))
+		mddev->recovery_cp = le64_to_cpu(sb->array_resync_offset);
+
+	/*
+	 * During load, we set FirstUse if a new superblock was written.
+	 * There are two reasons we might not have a superblock:
+	 * 1) The array is brand new - in which case, all of the
+	 *    devices must have their In_sync bit set.  Also,
+	 *    recovery_cp must be 0, unless forced.
+	 * 2) This is a new device being added to an old array
+	 *    and the new device needs to be rebuilt - in which
+	 *    case the In_sync bit will /not/ be set and
+	 *    recovery_cp must be MaxSector.
+	 */
+	rdev_for_each(r, mddev) {
+		if (!test_bit(In_sync, &r->flags)) {
+			DMINFO("Device %d specified for rebuild: "
+			       "Clearing superblock", r->raid_disk);
+			rebuilds++;
+		} else if (test_bit(FirstUse, &r->flags))
+			new_devs++;
+	}
+
+	if (!rebuilds) {
+		if (new_devs == mddev->raid_disks) {
+			DMINFO("Superblocks created for new array");
+			set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
+		} else if (new_devs) {
+			DMERR("New device injected "
+			      "into existing array without 'rebuild' "
+			      "parameter specified");
+			return -EINVAL;
+		}
+	} else if (new_devs) {
+		DMERR("'rebuild' devices cannot be "
+		      "injected into an array with other first-time devices");
+		return -EINVAL;
+	} else if (mddev->recovery_cp != MaxSector) {
+		DMERR("'rebuild' specified while array is not in-sync");
+		return -EINVAL;
+	}
+
+	/*
+	 * Now we set the Faulty bit for those devices that are
+	 * recorded in the superblock as failed.
+	 */
+	rdev_for_each(r, mddev) {
+		if (!r->sb_page)
+			continue;
+		sb2 = page_address(r->sb_page);
+		sb2->failed_devices = 0;
+
+		/*
+		 * Check for any device re-ordering.
+		 */
+		if (!test_bit(FirstUse, &r->flags) && (r->raid_disk >= 0)) {
+			role = le32_to_cpu(sb2->array_position);
+			if (role != r->raid_disk) {
+				if (rs->raid_type->level != 1) {
+					rs->ti->error = "Cannot change device "
+						"positions in RAID array";
+					return -EINVAL;
+				}
+				DMINFO("RAID1 device #%d now at position #%d",
+				       role, r->raid_disk);
+			}
+
+			/*
+			 * Partial recovery is performed on
+			 * returning failed devices.
+			 */
+			if (failed_devices & (1 << role))
+				set_bit(Faulty, &r->flags);
+		}
+	}
+
+	return 0;
+}
+
+static int super_validate(struct mddev *mddev, struct md_rdev *rdev)
+{
+	struct dm_raid_superblock *sb = page_address(rdev->sb_page);
+
+	/*
+	 * If mddev->events is not set, we know we have not yet initialized
+	 * the array.
+	 */
+	if (!mddev->events && super_init_validation(mddev, rdev))
+		return -EINVAL;
+
+	mddev->bitmap_info.offset = 4096 >> 9; /* Enable bitmap creation */
+	rdev->mddev->bitmap_info.default_offset = 4096 >> 9;
+	if (!test_bit(FirstUse, &rdev->flags)) {
+		rdev->recovery_offset = le64_to_cpu(sb->disk_recovery_offset);
+		if (rdev->recovery_offset != MaxSector)
+			clear_bit(In_sync, &rdev->flags);
+	}
+
+	/*
+	 * If a device comes back, set it as not In_sync and no longer faulty.
+	 */
+	if (test_bit(Faulty, &rdev->flags)) {
+		clear_bit(Faulty, &rdev->flags);
+		clear_bit(In_sync, &rdev->flags);
+		rdev->saved_raid_disk = rdev->raid_disk;
+		rdev->recovery_offset = 0;
+	}
+
+	clear_bit(FirstUse, &rdev->flags);
+
+	return 0;
+}
+
+/*
+ * Analyse superblocks and select the freshest.
+ */
+static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
+{
+	int ret;
+	struct raid_dev *dev;
+	struct md_rdev *rdev, *tmp, *freshest;
+	struct mddev *mddev = &rs->md;
+
+	freshest = NULL;
+	rdev_for_each_safe(rdev, tmp, mddev) {
+		/*
+		 * Skipping super_load due to DMPF_SYNC will cause
+		 * the array to undergo initialization again as
+		 * though it were new.  This is the intended effect
+		 * of the "sync" directive.
+		 *
+		 * When reshaping capability is added, we must ensure
+		 * that the "sync" directive is disallowed during the
+		 * reshape.
+		 */
+		if (rs->print_flags & DMPF_SYNC)
+			continue;
+
+		if (!rdev->meta_bdev)
+			continue;
+
+		ret = super_load(rdev, freshest);
+
+		switch (ret) {
+		case 1:
+			freshest = rdev;
+			break;
+		case 0:
+			break;
+		default:
+			dev = container_of(rdev, struct raid_dev, rdev);
+			if (dev->meta_dev)
+				dm_put_device(ti, dev->meta_dev);
+
+			dev->meta_dev = NULL;
+			rdev->meta_bdev = NULL;
+
+			if (rdev->sb_page)
+				put_page(rdev->sb_page);
+
+			rdev->sb_page = NULL;
+
+			rdev->sb_loaded = 0;
+
+			/*
+			 * We might be able to salvage the data device
+			 * even though the meta device has failed.  For
+			 * now, we behave as though '- -' had been
+			 * set for this device in the table.
+			 */
+			if (dev->data_dev)
+				dm_put_device(ti, dev->data_dev);
+
+			dev->data_dev = NULL;
+			rdev->bdev = NULL;
+
+			list_del(&rdev->same_set);
+		}
+	}
+
+	if (!freshest)
+		return 0;
+
+	if (validate_raid_redundancy(rs)) {
+		rs->ti->error = "Insufficient redundancy to activate array";
+		return -EINVAL;
+	}
+
+	/*
+	 * Validation of the freshest device provides the source of
+	 * validation for the remaining devices.
+	 */
+	ti->error = "Unable to assemble array: Invalid superblocks";
+	if (super_validate(mddev, freshest))
+		return -EINVAL;
+
+	rdev_for_each(rdev, mddev)
+		if ((rdev != freshest) && super_validate(mddev, rdev))
+			return -EINVAL;
+
+	return 0;
+}
+
+/*
+ * Enable/disable discard support on RAID set depending on
+ * RAID level and discard properties of underlying RAID members.
+ */
+static void configure_discard_support(struct dm_target *ti, struct raid_set *rs)
+{
+	int i;
+	bool raid456;
+
+	/* Assume discards not supported until after checks below. */
+	ti->discards_supported = false;
+
+	/* RAID level 4,5,6 require discard_zeroes_data for data integrity! */
+	raid456 = (rs->md.level == 4 || rs->md.level == 5 || rs->md.level == 6);
+
+	for (i = 0; i < rs->md.raid_disks; i++) {
+		struct request_queue *q;
+
+		if (!rs->dev[i].rdev.bdev)
+			continue;
+
+		q = bdev_get_queue(rs->dev[i].rdev.bdev);
+		if (!q || !blk_queue_discard(q))
+			return;
+
+		if (raid456) {
+			if (!q->limits.discard_zeroes_data)
+				return;
+			if (!devices_handle_discard_safely) {
+				DMERR("raid456 discard support disabled due to discard_zeroes_data uncertainty.");
+				DMERR("Set dm-raid.devices_handle_discard_safely=Y to override.");
+				return;
+			}
+		}
+	}
+
+	/* All RAID members properly support discards */
+	ti->discards_supported = true;
+
+	/*
+	 * RAID1 and RAID10 personalities require bio splitting,
+	 * RAID0/4/5/6 don't and process large discard bios properly.
+	 */
+	ti->split_discard_bios = !!(rs->md.level == 1 || rs->md.level == 10);
+	ti->num_discard_bios = 1;
+}
+
+/*
+ * Construct a RAID4/5/6 mapping:
+ * Args:
+ *	<raid_type> <#raid_params> <raid_params>		\
+ *	<#raid_devs> { <meta_dev1> <dev1> .. <meta_devN> <devN> }
+ *
+ * <raid_params> varies by <raid_type>.  See 'parse_raid_params' for
+ * details on possible <raid_params>.
+ */
+static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
+{
+	int ret;
+	struct raid_type *rt;
+	unsigned long num_raid_params, num_raid_devs;
+	struct raid_set *rs = NULL;
+
+	/* Must have at least <raid_type> <#raid_params> */
+	if (argc < 2) {
+		ti->error = "Too few arguments";
+		return -EINVAL;
+	}
+
+	/* raid type */
+	rt = get_raid_type(argv[0]);
+	if (!rt) {
+		ti->error = "Unrecognised raid_type";
+		return -EINVAL;
+	}
+	argc--;
+	argv++;
+
+	/* number of RAID parameters */
+	if (kstrtoul(argv[0], 10, &num_raid_params) < 0) {
+		ti->error = "Cannot understand number of RAID parameters";
+		return -EINVAL;
+	}
+	argc--;
+	argv++;
+
+	/* Skip over RAID params for now and find out # of devices */
+	if (num_raid_params >= argc) {
+		ti->error = "Arguments do not agree with counts given";
+		return -EINVAL;
+	}
+
+	if ((kstrtoul(argv[num_raid_params], 10, &num_raid_devs) < 0) ||
+	    (num_raid_devs >= INT_MAX)) {
+		ti->error = "Cannot understand number of raid devices";
+		return -EINVAL;
+	}
+
+	argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */
+	if (argc != (num_raid_devs * 2)) {
+		ti->error = "Supplied RAID devices does not match the count given";
+		return -EINVAL;
+	}
+
+	rs = context_alloc(ti, rt, (unsigned)num_raid_devs);
+	if (IS_ERR(rs))
+		return PTR_ERR(rs);
+
+	ret = parse_raid_params(rs, argv, (unsigned)num_raid_params);
+	if (ret)
+		goto bad;
+
+	argv += num_raid_params + 1;
+
+	ret = dev_parms(rs, argv);
+	if (ret)
+		goto bad;
+
+	rs->md.sync_super = super_sync;
+	ret = analyse_superblocks(ti, rs);
+	if (ret)
+		goto bad;
+
+	INIT_WORK(&rs->md.event_work, do_table_event);
+	ti->private = rs;
+	ti->num_flush_bios = 1;
+
+	/*
+	 * Disable/enable discard support on RAID set.
+	 */
+	configure_discard_support(ti, rs);
+
+	mutex_lock(&rs->md.reconfig_mutex);
+	ret = md_run(&rs->md);
+	rs->md.in_sync = 0; /* Assume already marked dirty */
+	mutex_unlock(&rs->md.reconfig_mutex);
+
+	if (ret) {
+		ti->error = "Fail to run raid array";
+		goto bad;
+	}
+
+	if (ti->len != rs->md.array_sectors) {
+		ti->error = "Array size does not match requested target length";
+		ret = -EINVAL;
+		goto size_mismatch;
+	}
+	rs->callbacks.congested_fn = raid_is_congested;
+	dm_table_add_target_callbacks(ti->table, &rs->callbacks);
+
+	mddev_suspend(&rs->md);
+	return 0;
+
+size_mismatch:
+	md_stop(&rs->md);
+bad:
+	context_free(rs);
+
+	return ret;
+}
+
+static void raid_dtr(struct dm_target *ti)
+{
+	struct raid_set *rs = ti->private;
+
+	list_del_init(&rs->callbacks.list);
+	md_stop(&rs->md);
+	context_free(rs);
+}
+
+static int raid_map(struct dm_target *ti, struct bio *bio)
+{
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
+
+	mddev->pers->make_request(mddev, bio);
+
+	return DM_MAPIO_SUBMITTED;
+}
+
+static const char *decipher_sync_action(struct mddev *mddev)
+{
+	if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+		return "frozen";
+
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+	    (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
+		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+			return "reshape";
+
+		if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
+			if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+				return "resync";
+			else if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
+				return "check";
+			return "repair";
+		}
+
+		if (test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
+			return "recover";
+	}
+
+	return "idle";
+}
+
+static void raid_status(struct dm_target *ti, status_type_t type,
+			unsigned status_flags, char *result, unsigned maxlen)
+{
+	struct raid_set *rs = ti->private;
+	unsigned raid_param_cnt = 1; /* at least 1 for chunksize */
+	unsigned sz = 0;
+	int i, array_in_sync = 0;
+	sector_t sync;
+
+	switch (type) {
+	case STATUSTYPE_INFO:
+		DMEMIT("%s %d ", rs->raid_type->name, rs->md.raid_disks);
+
+		if (test_bit(MD_RECOVERY_RUNNING, &rs->md.recovery))
+			sync = rs->md.curr_resync_completed;
+		else
+			sync = rs->md.recovery_cp;
+
+		if (sync >= rs->md.resync_max_sectors) {
+			/*
+			 * Sync complete.
+			 */
+			array_in_sync = 1;
+			sync = rs->md.resync_max_sectors;
+		} else if (test_bit(MD_RECOVERY_REQUESTED, &rs->md.recovery)) {
+			/*
+			 * If "check" or "repair" is occurring, the array has
+			 * undergone and initial sync and the health characters
+			 * should not be 'a' anymore.
+			 */
+			array_in_sync = 1;
+		} else {
+			/*
+			 * The array may be doing an initial sync, or it may
+			 * be rebuilding individual components.  If all the
+			 * devices are In_sync, then it is the array that is
+			 * being initialized.
+			 */
+			for (i = 0; i < rs->md.raid_disks; i++)
+				if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
+					array_in_sync = 1;
+		}
+
+		/*
+		 * Status characters:
+		 *  'D' = Dead/Failed device
+		 *  'a' = Alive but not in-sync
+		 *  'A' = Alive and in-sync
+		 */
+		for (i = 0; i < rs->md.raid_disks; i++) {
+			if (test_bit(Faulty, &rs->dev[i].rdev.flags))
+				DMEMIT("D");
+			else if (!array_in_sync ||
+				 !test_bit(In_sync, &rs->dev[i].rdev.flags))
+				DMEMIT("a");
+			else
+				DMEMIT("A");
+		}
+
+		/*
+		 * In-sync ratio:
+		 *  The in-sync ratio shows the progress of:
+		 *   - Initializing the array
+		 *   - Rebuilding a subset of devices of the array
+		 *  The user can distinguish between the two by referring
+		 *  to the status characters.
+		 */
+		DMEMIT(" %llu/%llu",
+		       (unsigned long long) sync,
+		       (unsigned long long) rs->md.resync_max_sectors);
+
+		/*
+		 * Sync action:
+		 *   See Documentation/device-mapper/dm-raid.c for
+		 *   information on each of these states.
+		 */
+		DMEMIT(" %s", decipher_sync_action(&rs->md));
+
+		/*
+		 * resync_mismatches/mismatch_cnt
+		 *   This field shows the number of discrepancies found when
+		 *   performing a "check" of the array.
+		 */
+		DMEMIT(" %llu",
+		       (strcmp(rs->md.last_sync_action, "check")) ? 0 :
+		       (unsigned long long)
+		       atomic64_read(&rs->md.resync_mismatches));
+		break;
+	case STATUSTYPE_TABLE:
+		/* The string you would use to construct this array */
+		for (i = 0; i < rs->md.raid_disks; i++) {
+			if ((rs->print_flags & DMPF_REBUILD) &&
+			    rs->dev[i].data_dev &&
+			    !test_bit(In_sync, &rs->dev[i].rdev.flags))
+				raid_param_cnt += 2; /* for rebuilds */
+			if (rs->dev[i].data_dev &&
+			    test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+				raid_param_cnt += 2;
+		}
+
+		raid_param_cnt += (hweight32(rs->print_flags & ~DMPF_REBUILD) * 2);
+		if (rs->print_flags & (DMPF_SYNC | DMPF_NOSYNC))
+			raid_param_cnt--;
+
+		DMEMIT("%s %u %u", rs->raid_type->name,
+		       raid_param_cnt, rs->md.chunk_sectors);
+
+		if ((rs->print_flags & DMPF_SYNC) &&
+		    (rs->md.recovery_cp == MaxSector))
+			DMEMIT(" sync");
+		if (rs->print_flags & DMPF_NOSYNC)
+			DMEMIT(" nosync");
+
+		for (i = 0; i < rs->md.raid_disks; i++)
+			if ((rs->print_flags & DMPF_REBUILD) &&
+			    rs->dev[i].data_dev &&
+			    !test_bit(In_sync, &rs->dev[i].rdev.flags))
+				DMEMIT(" rebuild %u", i);
+
+		if (rs->print_flags & DMPF_DAEMON_SLEEP)
+			DMEMIT(" daemon_sleep %lu",
+			       rs->md.bitmap_info.daemon_sleep);
+
+		if (rs->print_flags & DMPF_MIN_RECOVERY_RATE)
+			DMEMIT(" min_recovery_rate %d", rs->md.sync_speed_min);
+
+		if (rs->print_flags & DMPF_MAX_RECOVERY_RATE)
+			DMEMIT(" max_recovery_rate %d", rs->md.sync_speed_max);
+
+		for (i = 0; i < rs->md.raid_disks; i++)
+			if (rs->dev[i].data_dev &&
+			    test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+				DMEMIT(" write_mostly %u", i);
+
+		if (rs->print_flags & DMPF_MAX_WRITE_BEHIND)
+			DMEMIT(" max_write_behind %lu",
+			       rs->md.bitmap_info.max_write_behind);
+
+		if (rs->print_flags & DMPF_STRIPE_CACHE) {
+			struct r5conf *conf = rs->md.private;
+
+			/* convert from kiB to sectors */
+			DMEMIT(" stripe_cache %d",
+			       conf ? conf->max_nr_stripes * 2 : 0);
+		}
+
+		if (rs->print_flags & DMPF_REGION_SIZE)
+			DMEMIT(" region_size %lu",
+			       rs->md.bitmap_info.chunksize >> 9);
+
+		if (rs->print_flags & DMPF_RAID10_COPIES)
+			DMEMIT(" raid10_copies %u",
+			       raid10_md_layout_to_copies(rs->md.layout));
+
+		if (rs->print_flags & DMPF_RAID10_FORMAT)
+			DMEMIT(" raid10_format %s",
+			       raid10_md_layout_to_format(rs->md.layout));
+
+		DMEMIT(" %d", rs->md.raid_disks);
+		for (i = 0; i < rs->md.raid_disks; i++) {
+			if (rs->dev[i].meta_dev)
+				DMEMIT(" %s", rs->dev[i].meta_dev->name);
+			else
+				DMEMIT(" -");
+
+			if (rs->dev[i].data_dev)
+				DMEMIT(" %s", rs->dev[i].data_dev->name);
+			else
+				DMEMIT(" -");
+		}
+	}
+}
+
+static int raid_message(struct dm_target *ti, unsigned argc, char **argv)
+{
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
+
+	if (!strcasecmp(argv[0], "reshape")) {
+		DMERR("Reshape not supported.");
+		return -EINVAL;
+	}
+
+	if (!mddev->pers || !mddev->pers->sync_request)
+		return -EINVAL;
+
+	if (!strcasecmp(argv[0], "frozen"))
+		set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	else
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+
+	if (!strcasecmp(argv[0], "idle") || !strcasecmp(argv[0], "frozen")) {
+		if (mddev->sync_thread) {
+			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+			md_reap_sync_thread(mddev);
+		}
+	} else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+		   test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
+		return -EBUSY;
+	else if (!strcasecmp(argv[0], "resync"))
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	else if (!strcasecmp(argv[0], "recover")) {
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	} else {
+		if (!strcasecmp(argv[0], "check"))
+			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+		else if (!!strcasecmp(argv[0], "repair"))
+			return -EINVAL;
+		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;
+		if (!mddev->suspended)
+			md_wakeup_thread(mddev->sync_thread);
+	}
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	if (!mddev->suspended)
+		md_wakeup_thread(mddev->thread);
+
+	return 0;
+}
+
+static int raid_iterate_devices(struct dm_target *ti,
+				iterate_devices_callout_fn fn, void *data)
+{
+	struct raid_set *rs = ti->private;
+	unsigned i;
+	int ret = 0;
+
+	for (i = 0; !ret && i < rs->md.raid_disks; i++)
+		if (rs->dev[i].data_dev)
+			ret = fn(ti,
+				 rs->dev[i].data_dev,
+				 0, /* No offset on data devs */
+				 rs->md.dev_sectors,
+				 data);
+
+	return ret;
+}
+
+static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+	struct raid_set *rs = ti->private;
+	unsigned chunk_size = rs->md.chunk_sectors << 9;
+	struct r5conf *conf = rs->md.private;
+
+	blk_limits_io_min(limits, chunk_size);
+	blk_limits_io_opt(limits, chunk_size * (conf->raid_disks - conf->max_degraded));
+}
+
+static void raid_presuspend(struct dm_target *ti)
+{
+	struct raid_set *rs = ti->private;
+
+	md_stop_writes(&rs->md);
+}
+
+static void raid_postsuspend(struct dm_target *ti)
+{
+	struct raid_set *rs = ti->private;
+
+	mddev_suspend(&rs->md);
+}
+
+static void attempt_restore_of_faulty_devices(struct raid_set *rs)
+{
+	int i;
+	uint64_t failed_devices, cleared_failed_devices = 0;
+	unsigned long flags;
+	struct dm_raid_superblock *sb;
+	struct md_rdev *r;
+
+	for (i = 0; i < rs->md.raid_disks; i++) {
+		r = &rs->dev[i].rdev;
+		if (test_bit(Faulty, &r->flags) && r->sb_page &&
+		    sync_page_io(r, 0, r->sb_size, r->sb_page, READ, 1)) {
+			DMINFO("Faulty %s device #%d has readable super block."
+			       "  Attempting to revive it.",
+			       rs->raid_type->name, i);
+
+			/*
+			 * Faulty bit may be set, but sometimes the array can
+			 * be suspended before the personalities can respond
+			 * by removing the device from the array (i.e. calling
+			 * 'hot_remove_disk').  If they haven't yet removed
+			 * the failed device, its 'raid_disk' number will be
+			 * '>= 0' - meaning we must call this function
+			 * ourselves.
+			 */
+			if ((r->raid_disk >= 0) &&
+			    (r->mddev->pers->hot_remove_disk(r->mddev, r) != 0))
+				/* Failed to revive this device, try next */
+				continue;
+
+			r->raid_disk = i;
+			r->saved_raid_disk = i;
+			flags = r->flags;
+			clear_bit(Faulty, &r->flags);
+			clear_bit(WriteErrorSeen, &r->flags);
+			clear_bit(In_sync, &r->flags);
+			if (r->mddev->pers->hot_add_disk(r->mddev, r)) {
+				r->raid_disk = -1;
+				r->saved_raid_disk = -1;
+				r->flags = flags;
+			} else {
+				r->recovery_offset = 0;
+				cleared_failed_devices |= 1 << i;
+			}
+		}
+	}
+	if (cleared_failed_devices) {
+		rdev_for_each(r, &rs->md) {
+			sb = page_address(r->sb_page);
+			failed_devices = le64_to_cpu(sb->failed_devices);
+			failed_devices &= ~cleared_failed_devices;
+			sb->failed_devices = cpu_to_le64(failed_devices);
+		}
+	}
+}
+
+static void raid_resume(struct dm_target *ti)
+{
+	struct raid_set *rs = ti->private;
+
+	set_bit(MD_CHANGE_DEVS, &rs->md.flags);
+	if (!rs->bitmap_loaded) {
+		bitmap_load(&rs->md);
+		rs->bitmap_loaded = 1;
+	} else {
+		/*
+		 * A secondary resume while the device is active.
+		 * Take this opportunity to check whether any failed
+		 * devices are reachable again.
+		 */
+		attempt_restore_of_faulty_devices(rs);
+	}
+
+	clear_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
+	mddev_resume(&rs->md);
+}
+
+static struct target_type raid_target = {
+	.name = "raid",
+	.version = {1, 6, 0},
+	.module = THIS_MODULE,
+	.ctr = raid_ctr,
+	.dtr = raid_dtr,
+	.map = raid_map,
+	.status = raid_status,
+	.message = raid_message,
+	.iterate_devices = raid_iterate_devices,
+	.io_hints = raid_io_hints,
+	.presuspend = raid_presuspend,
+	.postsuspend = raid_postsuspend,
+	.resume = raid_resume,
+};
+
+static int __init dm_raid_init(void)
+{
+	DMINFO("Loading target version %u.%u.%u",
+	       raid_target.version[0],
+	       raid_target.version[1],
+	       raid_target.version[2]);
+	return dm_register_target(&raid_target);
+}
+
+static void __exit dm_raid_exit(void)
+{
+	dm_unregister_target(&raid_target);
+}
+
+module_init(dm_raid_init);
+module_exit(dm_raid_exit);
+
+module_param(devices_handle_discard_safely, bool, 0644);
+MODULE_PARM_DESC(devices_handle_discard_safely,
+		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
+
+MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target");
+MODULE_ALIAS("dm-raid1");
+MODULE_ALIAS("dm-raid10");
+MODULE_ALIAS("dm-raid4");
+MODULE_ALIAS("dm-raid5");
+MODULE_ALIAS("dm-raid6");
+MODULE_AUTHOR("Neil Brown <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");