Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4082 insertions, 0 deletions

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
new file mode 100644
index 000000000..b16332917
--- /dev/null
+++ b/drivers/md/dm-raid.c
@@ -0,0 +1,4082 @@
+/*
+ * Copyright (C) 2010-2011 Neil Brown
+ * Copyright (C) 2010-2018 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 "md-bitmap.h"
+
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "raid"
+#define	MAX_RAID_DEVICES	253 /* md-raid kernel limit */
+
+/*
+ * Minimum sectors of free reshape space per raid device
+ */
+#define	MIN_FREE_RESHAPE_SPACE to_sector(4*4096)
+
+/*
+ * Minimum journal space 4 MiB in sectors.
+ */
+#define	MIN_RAID456_JOURNAL_SPACE (4*2048)
+
+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;
+};
+
+/*
+ * Bits for establishing rs->ctr_flags
+ *
+ * 1 = no flag value
+ * 2 = flag with value
+ */
+#define __CTR_FLAG_SYNC			0  /* 1 */ /* Not with raid0! */
+#define __CTR_FLAG_NOSYNC		1  /* 1 */ /* Not with raid0! */
+#define __CTR_FLAG_REBUILD		2  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_DAEMON_SLEEP		3  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_MIN_RECOVERY_RATE	4  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_MAX_RECOVERY_RATE	5  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_MAX_WRITE_BEHIND	6  /* 2 */ /* Only with raid1! */
+#define __CTR_FLAG_WRITE_MOSTLY		7  /* 2 */ /* Only with raid1! */
+#define __CTR_FLAG_STRIPE_CACHE		8  /* 2 */ /* Only with raid4/5/6! */
+#define __CTR_FLAG_REGION_SIZE		9  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_RAID10_COPIES	10 /* 2 */ /* Only with raid10 */
+#define __CTR_FLAG_RAID10_FORMAT	11 /* 2 */ /* Only with raid10 */
+/* New for v1.9.0 */
+#define __CTR_FLAG_DELTA_DISKS		12 /* 2 */ /* Only with reshapable raid1/4/5/6/10! */
+#define __CTR_FLAG_DATA_OFFSET		13 /* 2 */ /* Only with reshapable raid4/5/6/10! */
+#define __CTR_FLAG_RAID10_USE_NEAR_SETS 14 /* 2 */ /* Only with raid10! */
+
+/* New for v1.10.0 */
+#define __CTR_FLAG_JOURNAL_DEV		15 /* 2 */ /* Only with raid4/5/6 (journal device)! */
+
+/* New for v1.11.1 */
+#define __CTR_FLAG_JOURNAL_MODE		16 /* 2 */ /* Only with raid4/5/6 (journal mode)! */
+
+/*
+ * Flags for rs->ctr_flags field.
+ */
+#define CTR_FLAG_SYNC			(1 << __CTR_FLAG_SYNC)
+#define CTR_FLAG_NOSYNC			(1 << __CTR_FLAG_NOSYNC)
+#define CTR_FLAG_REBUILD		(1 << __CTR_FLAG_REBUILD)
+#define CTR_FLAG_DAEMON_SLEEP		(1 << __CTR_FLAG_DAEMON_SLEEP)
+#define CTR_FLAG_MIN_RECOVERY_RATE	(1 << __CTR_FLAG_MIN_RECOVERY_RATE)
+#define CTR_FLAG_MAX_RECOVERY_RATE	(1 << __CTR_FLAG_MAX_RECOVERY_RATE)
+#define CTR_FLAG_MAX_WRITE_BEHIND	(1 << __CTR_FLAG_MAX_WRITE_BEHIND)
+#define CTR_FLAG_WRITE_MOSTLY		(1 << __CTR_FLAG_WRITE_MOSTLY)
+#define CTR_FLAG_STRIPE_CACHE		(1 << __CTR_FLAG_STRIPE_CACHE)
+#define CTR_FLAG_REGION_SIZE		(1 << __CTR_FLAG_REGION_SIZE)
+#define CTR_FLAG_RAID10_COPIES		(1 << __CTR_FLAG_RAID10_COPIES)
+#define CTR_FLAG_RAID10_FORMAT		(1 << __CTR_FLAG_RAID10_FORMAT)
+#define CTR_FLAG_DELTA_DISKS		(1 << __CTR_FLAG_DELTA_DISKS)
+#define CTR_FLAG_DATA_OFFSET		(1 << __CTR_FLAG_DATA_OFFSET)
+#define CTR_FLAG_RAID10_USE_NEAR_SETS	(1 << __CTR_FLAG_RAID10_USE_NEAR_SETS)
+#define CTR_FLAG_JOURNAL_DEV		(1 << __CTR_FLAG_JOURNAL_DEV)
+#define CTR_FLAG_JOURNAL_MODE		(1 << __CTR_FLAG_JOURNAL_MODE)
+
+/*
+ * Definitions of various constructor flags to
+ * be used in checks of valid / invalid flags
+ * per raid level.
+ */
+/* Define all any sync flags */
+#define	CTR_FLAGS_ANY_SYNC		(CTR_FLAG_SYNC | CTR_FLAG_NOSYNC)
+
+/* Define flags for options without argument (e.g. 'nosync') */
+#define	CTR_FLAG_OPTIONS_NO_ARGS	(CTR_FLAGS_ANY_SYNC | \
+					 CTR_FLAG_RAID10_USE_NEAR_SETS)
+
+/* Define flags for options with one argument (e.g. 'delta_disks +2') */
+#define CTR_FLAG_OPTIONS_ONE_ARG (CTR_FLAG_REBUILD | \
+				  CTR_FLAG_WRITE_MOSTLY | \
+				  CTR_FLAG_DAEMON_SLEEP | \
+				  CTR_FLAG_MIN_RECOVERY_RATE | \
+				  CTR_FLAG_MAX_RECOVERY_RATE | \
+				  CTR_FLAG_MAX_WRITE_BEHIND | \
+				  CTR_FLAG_STRIPE_CACHE | \
+				  CTR_FLAG_REGION_SIZE | \
+				  CTR_FLAG_RAID10_COPIES | \
+				  CTR_FLAG_RAID10_FORMAT | \
+				  CTR_FLAG_DELTA_DISKS | \
+				  CTR_FLAG_DATA_OFFSET)
+
+/* Valid options definitions per raid level... */
+
+/* "raid0" does only accept data offset */
+#define RAID0_VALID_FLAGS	(CTR_FLAG_DATA_OFFSET)
+
+/* "raid1" does not accept stripe cache, data offset, delta_disks or any raid10 options */
+#define RAID1_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
+				 CTR_FLAG_REBUILD | \
+				 CTR_FLAG_WRITE_MOSTLY | \
+				 CTR_FLAG_DAEMON_SLEEP | \
+				 CTR_FLAG_MIN_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_WRITE_BEHIND | \
+				 CTR_FLAG_REGION_SIZE | \
+				 CTR_FLAG_DELTA_DISKS | \
+				 CTR_FLAG_DATA_OFFSET)
+
+/* "raid10" does not accept any raid1 or stripe cache options */
+#define RAID10_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
+				 CTR_FLAG_REBUILD | \
+				 CTR_FLAG_DAEMON_SLEEP | \
+				 CTR_FLAG_MIN_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_RECOVERY_RATE | \
+				 CTR_FLAG_REGION_SIZE | \
+				 CTR_FLAG_RAID10_COPIES | \
+				 CTR_FLAG_RAID10_FORMAT | \
+				 CTR_FLAG_DELTA_DISKS | \
+				 CTR_FLAG_DATA_OFFSET | \
+				 CTR_FLAG_RAID10_USE_NEAR_SETS)
+
+/*
+ * "raid4/5/6" do not accept any raid1 or raid10 specific options
+ *
+ * "raid6" does not accept "nosync", because it is not guaranteed
+ * that both parity and q-syndrome are being written properly with
+ * any writes
+ */
+#define RAID45_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
+				 CTR_FLAG_REBUILD | \
+				 CTR_FLAG_DAEMON_SLEEP | \
+				 CTR_FLAG_MIN_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_RECOVERY_RATE | \
+				 CTR_FLAG_STRIPE_CACHE | \
+				 CTR_FLAG_REGION_SIZE | \
+				 CTR_FLAG_DELTA_DISKS | \
+				 CTR_FLAG_DATA_OFFSET | \
+				 CTR_FLAG_JOURNAL_DEV | \
+				 CTR_FLAG_JOURNAL_MODE)
+
+#define RAID6_VALID_FLAGS	(CTR_FLAG_SYNC | \
+				 CTR_FLAG_REBUILD | \
+				 CTR_FLAG_DAEMON_SLEEP | \
+				 CTR_FLAG_MIN_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_RECOVERY_RATE | \
+				 CTR_FLAG_STRIPE_CACHE | \
+				 CTR_FLAG_REGION_SIZE | \
+				 CTR_FLAG_DELTA_DISKS | \
+				 CTR_FLAG_DATA_OFFSET | \
+				 CTR_FLAG_JOURNAL_DEV | \
+				 CTR_FLAG_JOURNAL_MODE)
+/* ...valid options definitions per raid level */
+
+/*
+ * Flags for rs->runtime_flags field
+ * (RT_FLAG prefix meaning "runtime flag")
+ *
+ * These are all internal and used to define runtime state,
+ * e.g. to prevent another resume from preresume processing
+ * the raid set all over again.
+ */
+#define RT_FLAG_RS_PRERESUMED		0
+#define RT_FLAG_RS_RESUMED		1
+#define RT_FLAG_RS_BITMAP_LOADED	2
+#define RT_FLAG_UPDATE_SBS		3
+#define RT_FLAG_RESHAPE_RS		4
+#define RT_FLAG_RS_SUSPENDED		5
+#define RT_FLAG_RS_IN_SYNC		6
+#define RT_FLAG_RS_RESYNCING		7
+
+/* Array elements of 64 bit needed for rebuild/failed disk bits */
+#define DISKS_ARRAY_ELEMS ((MAX_RAID_DEVICES + (sizeof(uint64_t) * 8 - 1)) / sizeof(uint64_t) / 8)
+
+/*
+ * raid set level, layout and chunk sectors backup/restore
+ */
+struct rs_layout {
+	int new_level;
+	int new_layout;
+	int new_chunk_sectors;
+};
+
+struct raid_set {
+	struct dm_target *ti;
+
+	uint32_t stripe_cache_entries;
+	unsigned long ctr_flags;
+	unsigned long runtime_flags;
+
+	uint64_t rebuild_disks[DISKS_ARRAY_ELEMS];
+
+	int raid_disks;
+	int delta_disks;
+	int data_offset;
+	int raid10_copies;
+	int requested_bitmap_chunk_sectors;
+
+	struct mddev md;
+	struct raid_type *raid_type;
+	struct dm_target_callbacks callbacks;
+
+	/* Optional raid4/5/6 journal device */
+	struct journal_dev {
+		struct dm_dev *dev;
+		struct md_rdev rdev;
+		int mode;
+	} journal_dev;
+
+	struct raid_dev dev[0];
+};
+
+static void rs_config_backup(struct raid_set *rs, struct rs_layout *l)
+{
+	struct mddev *mddev = &rs->md;
+
+	l->new_level = mddev->new_level;
+	l->new_layout = mddev->new_layout;
+	l->new_chunk_sectors = mddev->new_chunk_sectors;
+}
+
+static void rs_config_restore(struct raid_set *rs, struct rs_layout *l)
+{
+	struct mddev *mddev = &rs->md;
+
+	mddev->new_level = l->new_level;
+	mddev->new_layout = l->new_layout;
+	mddev->new_chunk_sectors = l->new_chunk_sectors;
+}
+
+/* raid10 algorithms (i.e. formats) */
+#define	ALGORITHM_RAID10_DEFAULT	0
+#define	ALGORITHM_RAID10_NEAR		1
+#define	ALGORITHM_RAID10_OFFSET		2
+#define	ALGORITHM_RAID10_FAR		3
+
+/* Supported raid types and properties. */
+static struct raid_type {
+	const char *name;		/* RAID algorithm. */
+	const char *descr;		/* Descriptor text for logging. */
+	const unsigned int parity_devs;	/* # of parity devices. */
+	const unsigned int minimal_devs;/* minimal # of devices in set. */
+	const unsigned int level;	/* RAID level. */
+	const unsigned int algorithm;	/* RAID algorithm. */
+} raid_types[] = {
+	{"raid0",	  "raid0 (striping)",			    0, 2, 0,  0 /* NONE */},
+	{"raid1",	  "raid1 (mirroring)",			    0, 2, 1,  0 /* NONE */},
+	{"raid10_far",	  "raid10 far (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_FAR},
+	{"raid10_offset", "raid10 offset (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_OFFSET},
+	{"raid10_near",	  "raid10 near (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_NEAR},
+	{"raid10",	  "raid10 (striped mirrors)",		    0, 2, 10, ALGORITHM_RAID10_DEFAULT},
+	{"raid4",	  "raid4 (dedicated first parity disk)",    1, 2, 5,  ALGORITHM_PARITY_0}, /* raid4 layout = raid5_0 */
+	{"raid5_n",	  "raid5 (dedicated last parity disk)",	    1, 2, 5,  ALGORITHM_PARITY_N},
+	{"raid5_ls",	  "raid5 (left symmetric)",		    1, 2, 5,  ALGORITHM_LEFT_SYMMETRIC},
+	{"raid5_rs",	  "raid5 (right symmetric)",		    1, 2, 5,  ALGORITHM_RIGHT_SYMMETRIC},
+	{"raid5_la",	  "raid5 (left asymmetric)",		    1, 2, 5,  ALGORITHM_LEFT_ASYMMETRIC},
+	{"raid5_ra",	  "raid5 (right asymmetric)",		    1, 2, 5,  ALGORITHM_RIGHT_ASYMMETRIC},
+	{"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},
+	{"raid6_n_6",	  "raid6 (dedicated parity/Q n/6)",	    2, 4, 6,  ALGORITHM_PARITY_N_6},
+	{"raid6_ls_6",	  "raid6 (left symmetric dedicated Q 6)",   2, 4, 6,  ALGORITHM_LEFT_SYMMETRIC_6},
+	{"raid6_rs_6",	  "raid6 (right symmetric dedicated Q 6)",  2, 4, 6,  ALGORITHM_RIGHT_SYMMETRIC_6},
+	{"raid6_la_6",	  "raid6 (left asymmetric dedicated Q 6)",  2, 4, 6,  ALGORITHM_LEFT_ASYMMETRIC_6},
+	{"raid6_ra_6",	  "raid6 (right asymmetric dedicated Q 6)", 2, 4, 6,  ALGORITHM_RIGHT_ASYMMETRIC_6}
+};
+
+/* True, if @v is in inclusive range [@min, @max] */
+static bool __within_range(long v, long min, long max)
+{
+	return v >= min && v <= max;
+}
+
+/* All table line arguments are defined here */
+static struct arg_name_flag {
+	const unsigned long flag;
+	const char *name;
+} __arg_name_flags[] = {
+	{ CTR_FLAG_SYNC, "sync"},
+	{ CTR_FLAG_NOSYNC, "nosync"},
+	{ CTR_FLAG_REBUILD, "rebuild"},
+	{ CTR_FLAG_DAEMON_SLEEP, "daemon_sleep"},
+	{ CTR_FLAG_MIN_RECOVERY_RATE, "min_recovery_rate"},
+	{ CTR_FLAG_MAX_RECOVERY_RATE, "max_recovery_rate"},
+	{ CTR_FLAG_MAX_WRITE_BEHIND, "max_write_behind"},
+	{ CTR_FLAG_WRITE_MOSTLY, "write_mostly"},
+	{ CTR_FLAG_STRIPE_CACHE, "stripe_cache"},
+	{ CTR_FLAG_REGION_SIZE, "region_size"},
+	{ CTR_FLAG_RAID10_COPIES, "raid10_copies"},
+	{ CTR_FLAG_RAID10_FORMAT, "raid10_format"},
+	{ CTR_FLAG_DATA_OFFSET, "data_offset"},
+	{ CTR_FLAG_DELTA_DISKS, "delta_disks"},
+	{ CTR_FLAG_RAID10_USE_NEAR_SETS, "raid10_use_near_sets"},
+	{ CTR_FLAG_JOURNAL_DEV, "journal_dev" },
+	{ CTR_FLAG_JOURNAL_MODE, "journal_mode" },
+};
+
+/* Return argument name string for given @flag */
+static const char *dm_raid_arg_name_by_flag(const uint32_t flag)
+{
+	if (hweight32(flag) == 1) {
+		struct arg_name_flag *anf = __arg_name_flags + ARRAY_SIZE(__arg_name_flags);
+
+		while (anf-- > __arg_name_flags)
+			if (flag & anf->flag)
+				return anf->name;
+
+	} else
+		DMERR("%s called with more than one flag!", __func__);
+
+	return NULL;
+}
+
+/* Define correlation of raid456 journal cache modes and dm-raid target line parameters */
+static struct {
+	const int mode;
+	const char *param;
+} _raid456_journal_mode[] = {
+	{ R5C_JOURNAL_MODE_WRITE_THROUGH , "writethrough" },
+	{ R5C_JOURNAL_MODE_WRITE_BACK    , "writeback" }
+};
+
+/* Return MD raid4/5/6 journal mode for dm @journal_mode one */
+static int dm_raid_journal_mode_to_md(const char *mode)
+{
+	int m = ARRAY_SIZE(_raid456_journal_mode);
+
+	while (m--)
+		if (!strcasecmp(mode, _raid456_journal_mode[m].param))
+			return _raid456_journal_mode[m].mode;
+
+	return -EINVAL;
+}
+
+/* Return dm-raid raid4/5/6 journal mode string for @mode */
+static const char *md_journal_mode_to_dm_raid(const int mode)
+{
+	int m = ARRAY_SIZE(_raid456_journal_mode);
+
+	while (m--)
+		if (mode == _raid456_journal_mode[m].mode)
+			return _raid456_journal_mode[m].param;
+
+	return "unknown";
+}
+
+/*
+ * Bool helpers to test for various raid levels of a raid set.
+ * It's level as reported by the superblock rather than
+ * the requested raid_type passed to the constructor.
+ */
+/* Return true, if raid set in @rs is raid0 */
+static bool rs_is_raid0(struct raid_set *rs)
+{
+	return !rs->md.level;
+}
+
+/* Return true, if raid set in @rs is raid1 */
+static bool rs_is_raid1(struct raid_set *rs)
+{
+	return rs->md.level == 1;
+}
+
+/* Return true, if raid set in @rs is raid10 */
+static bool rs_is_raid10(struct raid_set *rs)
+{
+	return rs->md.level == 10;
+}
+
+/* Return true, if raid set in @rs is level 6 */
+static bool rs_is_raid6(struct raid_set *rs)
+{
+	return rs->md.level == 6;
+}
+
+/* Return true, if raid set in @rs is level 4, 5 or 6 */
+static bool rs_is_raid456(struct raid_set *rs)
+{
+	return __within_range(rs->md.level, 4, 6);
+}
+
+/* Return true, if raid set in @rs is reshapable */
+static bool __is_raid10_far(int layout);
+static bool rs_is_reshapable(struct raid_set *rs)
+{
+	return rs_is_raid456(rs) ||
+	       (rs_is_raid10(rs) && !__is_raid10_far(rs->md.new_layout));
+}
+
+/* Return true, if raid set in @rs is recovering */
+static bool rs_is_recovering(struct raid_set *rs)
+{
+	return rs->md.recovery_cp < rs->md.dev_sectors;
+}
+
+/* Return true, if raid set in @rs is reshaping */
+static bool rs_is_reshaping(struct raid_set *rs)
+{
+	return rs->md.reshape_position != MaxSector;
+}
+
+/*
+ * bool helpers to test for various raid levels of a raid type @rt
+ */
+
+/* Return true, if raid type in @rt is raid0 */
+static bool rt_is_raid0(struct raid_type *rt)
+{
+	return !rt->level;
+}
+
+/* Return true, if raid type in @rt is raid1 */
+static bool rt_is_raid1(struct raid_type *rt)
+{
+	return rt->level == 1;
+}
+
+/* Return true, if raid type in @rt is raid10 */
+static bool rt_is_raid10(struct raid_type *rt)
+{
+	return rt->level == 10;
+}
+
+/* Return true, if raid type in @rt is raid4/5 */
+static bool rt_is_raid45(struct raid_type *rt)
+{
+	return __within_range(rt->level, 4, 5);
+}
+
+/* Return true, if raid type in @rt is raid6 */
+static bool rt_is_raid6(struct raid_type *rt)
+{
+	return rt->level == 6;
+}
+
+/* Return true, if raid type in @rt is raid4/5/6 */
+static bool rt_is_raid456(struct raid_type *rt)
+{
+	return __within_range(rt->level, 4, 6);
+}
+/* END: raid level bools */
+
+/* Return valid ctr flags for the raid level of @rs */
+static unsigned long __valid_flags(struct raid_set *rs)
+{
+	if (rt_is_raid0(rs->raid_type))
+		return RAID0_VALID_FLAGS;
+	else if (rt_is_raid1(rs->raid_type))
+		return RAID1_VALID_FLAGS;
+	else if (rt_is_raid10(rs->raid_type))
+		return RAID10_VALID_FLAGS;
+	else if (rt_is_raid45(rs->raid_type))
+		return RAID45_VALID_FLAGS;
+	else if (rt_is_raid6(rs->raid_type))
+		return RAID6_VALID_FLAGS;
+
+	return 0;
+}
+
+/*
+ * Check for valid flags set on @rs
+ *
+ * Has to be called after parsing of the ctr flags!
+ */
+static int rs_check_for_valid_flags(struct raid_set *rs)
+{
+	if (rs->ctr_flags & ~__valid_flags(rs)) {
+		rs->ti->error = "Invalid flags combination";
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* MD raid10 bit definitions and helpers */
+#define RAID10_OFFSET			(1 << 16) /* stripes with data copies area adjacent on devices */
+#define RAID10_BROCKEN_USE_FAR_SETS	(1 << 17) /* Broken in raid10.c: use sets instead of whole stripe rotation */
+#define RAID10_USE_FAR_SETS		(1 << 18) /* Use sets instead of whole stripe rotation */
+#define RAID10_FAR_COPIES_SHIFT		8	  /* raid10 # far copies shift (2nd byte of layout) */
+
+/* Return md raid10 near copies for @layout */
+static unsigned int __raid10_near_copies(int layout)
+{
+	return layout & 0xFF;
+}
+
+/* Return md raid10 far copies for @layout */
+static unsigned int __raid10_far_copies(int layout)
+{
+	return __raid10_near_copies(layout >> RAID10_FAR_COPIES_SHIFT);
+}
+
+/* Return true if md raid10 offset for @layout */
+static bool __is_raid10_offset(int layout)
+{
+	return !!(layout & RAID10_OFFSET);
+}
+
+/* Return true if md raid10 near for @layout */
+static bool __is_raid10_near(int layout)
+{
+	return !__is_raid10_offset(layout) && __raid10_near_copies(layout) > 1;
+}
+
+/* Return true if md raid10 far for @layout */
+static bool __is_raid10_far(int layout)
+{
+	return !__is_raid10_offset(layout) && __raid10_far_copies(layout) > 1;
+}
+
+/* Return md raid10 layout string for @layout */
+static const char *raid10_md_layout_to_format(int layout)
+{
+	/*
+	 * Bit 16 stands for "offset"
+	 * (i.e. adjacent stripes hold copies)
+	 *
+	 * Refer to MD's raid10.c for details
+	 */
+	if (__is_raid10_offset(layout))
+		return "offset";
+
+	if (__raid10_near_copies(layout) > 1)
+		return "near";
+
+	if (__raid10_far_copies(layout) > 1)
+		return "far";
+
+	return "unknown";
+}
+
+/* Return md raid10 algorithm for @name */
+static int raid10_name_to_format(const char *name)
+{
+	if (!strcasecmp(name, "near"))
+		return ALGORITHM_RAID10_NEAR;
+	else if (!strcasecmp(name, "offset"))
+		return ALGORITHM_RAID10_OFFSET;
+	else if (!strcasecmp(name, "far"))
+		return ALGORITHM_RAID10_FAR;
+
+	return -EINVAL;
+}
+
+/* Return md raid10 copies for @layout */
+static unsigned int raid10_md_layout_to_copies(int layout)
+{
+	return max(__raid10_near_copies(layout), __raid10_far_copies(layout));
+}
+
+/* Return md raid10 format id for @format string */
+static int raid10_format_to_md_layout(struct raid_set *rs,
+				      unsigned int algorithm,
+				      unsigned int copies)
+{
+	unsigned int n = 1, f = 1, r = 0;
+
+	/*
+	 * MD resilienece flaw:
+	 *
+	 * enabling use_far_sets for far/offset formats causes copies
+	 * to be colocated on the same devs together with their origins!
+	 *
+	 * -> disable it for now in the definition above
+	 */
+	if (algorithm == ALGORITHM_RAID10_DEFAULT ||
+	    algorithm == ALGORITHM_RAID10_NEAR)
+		n = copies;
+
+	else if (algorithm == ALGORITHM_RAID10_OFFSET) {
+		f = copies;
+		r = RAID10_OFFSET;
+		if (!test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags))
+			r |= RAID10_USE_FAR_SETS;
+
+	} else if (algorithm == ALGORITHM_RAID10_FAR) {
+		f = copies;
+		r = !RAID10_OFFSET;
+		if (!test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags))
+			r |= RAID10_USE_FAR_SETS;
+
+	} else
+		return -EINVAL;
+
+	return r | (f << RAID10_FAR_COPIES_SHIFT) | n;
+}
+/* END: MD raid10 bit definitions and helpers */
+
+/* Check for any of the raid10 algorithms */
+static bool __got_raid10(struct raid_type *rtp, const int layout)
+{
+	if (rtp->level == 10) {
+		switch (rtp->algorithm) {
+		case ALGORITHM_RAID10_DEFAULT:
+		case ALGORITHM_RAID10_NEAR:
+			return __is_raid10_near(layout);
+		case ALGORITHM_RAID10_OFFSET:
+			return __is_raid10_offset(layout);
+		case ALGORITHM_RAID10_FAR:
+			return __is_raid10_far(layout);
+		default:
+			break;
+		}
+	}
+
+	return false;
+}
+
+/* Return raid_type for @name */
+static struct raid_type *get_raid_type(const char *name)
+{
+	struct raid_type *rtp = raid_types + ARRAY_SIZE(raid_types);
+
+	while (rtp-- > raid_types)
+		if (!strcasecmp(rtp->name, name))
+			return rtp;
+
+	return NULL;
+}
+
+/* Return raid_type for @name based derived from @level and @layout */
+static struct raid_type *get_raid_type_by_ll(const int level, const int layout)
+{
+	struct raid_type *rtp = raid_types + ARRAY_SIZE(raid_types);
+
+	while (rtp-- > raid_types) {
+		/* RAID10 special checks based on @layout flags/properties */
+		if (rtp->level == level &&
+		    (__got_raid10(rtp, layout) || rtp->algorithm == layout))
+			return rtp;
+	}
+
+	return NULL;
+}
+
+/* Adjust rdev sectors */
+static void rs_set_rdev_sectors(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *rdev;
+
+	/*
+	 * raid10 sets rdev->sector to the device size, which
+	 * is unintended in case of out-of-place reshaping
+	 */
+	rdev_for_each(rdev, mddev)
+		if (!test_bit(Journal, &rdev->flags))
+			rdev->sectors = mddev->dev_sectors;
+}
+
+/*
+ * Change bdev capacity of @rs in case of a disk add/remove reshape
+ */
+static void rs_set_capacity(struct raid_set *rs)
+{
+	struct gendisk *gendisk = dm_disk(dm_table_get_md(rs->ti->table));
+
+	set_capacity(gendisk, rs->md.array_sectors);
+	revalidate_disk(gendisk);
+}
+
+/*
+ * Set the mddev properties in @rs to the current
+ * ones retrieved from the freshest superblock
+ */
+static void rs_set_cur(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+
+	mddev->new_level = mddev->level;
+	mddev->new_layout = mddev->layout;
+	mddev->new_chunk_sectors = mddev->chunk_sectors;
+}
+
+/*
+ * Set the mddev properties in @rs to the new
+ * ones requested by the ctr
+ */
+static void rs_set_new(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+
+	mddev->level = mddev->new_level;
+	mddev->layout = mddev->new_layout;
+	mddev->chunk_sectors = mddev->new_chunk_sectors;
+	mddev->raid_disks = rs->raid_disks;
+	mddev->delta_disks = 0;
+}
+
+static struct raid_set *raid_set_alloc(struct dm_target *ti, struct raid_type *raid_type,
+				       unsigned int raid_devs)
+{
+	unsigned int i;
+	struct raid_set *rs;
+
+	if (raid_devs <= raid_type->parity_devs) {
+		ti->error = "Insufficient number of devices";
+		return ERR_PTR(-EINVAL);
+	}
+
+	rs = kzalloc(struct_size(rs, dev, raid_devs), GFP_KERNEL);
+	if (!rs) {
+		ti->error = "Cannot allocate raid context";
+		return ERR_PTR(-ENOMEM);
+	}
+
+	mddev_init(&rs->md);
+
+	rs->raid_disks = raid_devs;
+	rs->delta_disks = 0;
+
+	rs->ti = ti;
+	rs->raid_type = raid_type;
+	rs->stripe_cache_entries = 256;
+	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 = MaxSector;
+
+	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;
+}
+
+/* Free all @rs allocations */
+static void raid_set_free(struct raid_set *rs)
+{
+	int i;
+
+	if (rs->journal_dev.dev) {
+		md_rdev_clear(&rs->journal_dev.rdev);
+		dm_put_device(rs->ti, rs->journal_dev.dev);
+	}
+
+	for (i = 0; i < rs->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 raid_set_free() to unwind the operations.
+ */
+static int parse_dev_params(struct raid_set *rs, struct dm_arg_set *as)
+{
+	int i;
+	int rebuild = 0;
+	int metadata_available = 0;
+	int r = 0;
+	const char *arg;
+
+	/* Put off the number of raid devices argument to get to dev pairs */
+	arg = dm_shift_arg(as);
+	if (!arg)
+		return -EINVAL;
+
+	for (i = 0; i < rs->raid_disks; i++) {
+		rs->dev[i].rdev.raid_disk = i;
+
+		rs->dev[i].meta_dev = NULL;
+		rs->dev[i].data_dev = NULL;
+
+		/*
+		 * There are no offsets initially.
+		 * Out of place reshape will set them accordingly.
+		 */
+		rs->dev[i].rdev.data_offset = 0;
+		rs->dev[i].rdev.new_data_offset = 0;
+		rs->dev[i].rdev.mddev = &rs->md;
+
+		arg = dm_shift_arg(as);
+		if (!arg)
+			return -EINVAL;
+
+		if (strcmp(arg, "-")) {
+			r = dm_get_device(rs->ti, arg, dm_table_get_mode(rs->ti->table),
+					  &rs->dev[i].meta_dev);
+			if (r) {
+				rs->ti->error = "RAID metadata device lookup failure";
+				return r;
+			}
+
+			rs->dev[i].rdev.sb_page = alloc_page(GFP_KERNEL);
+			if (!rs->dev[i].rdev.sb_page) {
+				rs->ti->error = "Failed to allocate superblock page";
+				return -ENOMEM;
+			}
+		}
+
+		arg = dm_shift_arg(as);
+		if (!arg)
+			return -EINVAL;
+
+		if (!strcmp(arg, "-")) {
+			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;
+			}
+
+			if (rs->dev[i].meta_dev) {
+				rs->ti->error = "No data device supplied with metadata device";
+				return -EINVAL;
+			}
+
+			continue;
+		}
+
+		r = dm_get_device(rs->ti, arg, dm_table_get_mode(rs->ti->table),
+				  &rs->dev[i].data_dev);
+		if (r) {
+			rs->ti->error = "RAID device lookup failure";
+			return r;
+		}
+
+		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_tail(&rs->dev[i].rdev.same_set, &rs->md.disks);
+		if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
+			rebuild++;
+	}
+
+	if (rs->journal_dev.dev)
+		list_add_tail(&rs->journal_dev.rdev.same_set, &rs->md.disks);
+
+	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.
+		 */
+		rs->ti->error = "Unable to rebuild drive while array is not in-sync";
+		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 (rs_is_raid0(rs))
+		return 0;
+
+	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 */
+			region_size = roundup_pow_of_two(min_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 = to_bytes(region_size);
+
+	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 int i, rebuild_cnt = 0;
+	unsigned int rebuilds_per_group = 0, copies;
+	unsigned int 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->md.level) {
+	case 0:
+		break;
+	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.new_layout);
+		if (copies < 2) {
+			DMERR("Bogus raid10 data copies < 2!");
+			return -EINVAL;
+		}
+
+		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 (__is_raid10_near(rs->md.new_layout)) {
+			for (i = 0; i < rs->md.raid_disks; i++) {
+				if (!(i % copies))
+					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;
+		}
+
+		/*
+		 * 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
+ *    [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
+ *    [journal_dev <dev>]		raid4/5/6 journaling deviice
+ *    					(i.e. write hole closing log)
+ *
+ * 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, struct dm_arg_set *as,
+			     unsigned int num_raid_params)
+{
+	int value, raid10_format = ALGORITHM_RAID10_DEFAULT;
+	unsigned int raid10_copies = 2;
+	unsigned int i, write_mostly = 0;
+	unsigned int region_size = 0;
+	sector_t max_io_len;
+	const char *arg, *key;
+	struct raid_dev *rd;
+	struct raid_type *rt = rs->raid_type;
+
+	arg = dm_shift_arg(as);
+	num_raid_params--; /* Account for chunk_size argument */
+
+	if (kstrtoint(arg, 10, &value) < 0) {
+		rs->ti->error = "Bad numerical argument given for chunk_size";
+		return -EINVAL;
+	}
+
+	/*
+	 * First, parse the in-order required arguments
+	 * "chunk_size" is the only argument of this type.
+	 */
+	if (rt_is_raid1(rt)) {
+		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;
+
+	/*
+	 * 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->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++) {
+		key = dm_shift_arg(as);
+		if (!key) {
+			rs->ti->error = "Not enough raid parameters given";
+			return -EINVAL;
+		}
+
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_NOSYNC))) {
+			if (test_and_set_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
+				rs->ti->error = "Only one 'nosync' argument allowed";
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_SYNC))) {
+			if (test_and_set_bit(__CTR_FLAG_SYNC, &rs->ctr_flags)) {
+				rs->ti->error = "Only one 'sync' argument allowed";
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_USE_NEAR_SETS))) {
+			if (test_and_set_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags)) {
+				rs->ti->error = "Only one 'raid10_use_new_sets' argument allowed";
+				return -EINVAL;
+			}
+			continue;
+		}
+
+		arg = dm_shift_arg(as);
+		i++; /* Account for the argument pairs */
+		if (!arg) {
+			rs->ti->error = "Wrong number of raid parameters given";
+			return -EINVAL;
+		}
+
+		/*
+		 * Parameters that take a string value are checked here.
+		 */
+		/* "raid10_format {near|offset|far} */
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_FORMAT))) {
+			if (test_and_set_bit(__CTR_FLAG_RAID10_FORMAT, &rs->ctr_flags)) {
+				rs->ti->error = "Only one 'raid10_format' argument pair allowed";
+				return -EINVAL;
+			}
+			if (!rt_is_raid10(rt)) {
+				rs->ti->error = "'raid10_format' is an invalid parameter for this RAID type";
+				return -EINVAL;
+			}
+			raid10_format = raid10_name_to_format(arg);
+			if (raid10_format < 0) {
+				rs->ti->error = "Invalid 'raid10_format' value given";
+				return raid10_format;
+			}
+			continue;
+		}
+
+		/* "journal_dev <dev>" */
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_JOURNAL_DEV))) {
+			int r;
+			struct md_rdev *jdev;
+
+			if (test_and_set_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags)) {
+				rs->ti->error = "Only one raid4/5/6 set journaling device allowed";
+				return -EINVAL;
+			}
+			if (!rt_is_raid456(rt)) {
+				rs->ti->error = "'journal_dev' is an invalid parameter for this RAID type";
+				return -EINVAL;
+			}
+			r = dm_get_device(rs->ti, arg, dm_table_get_mode(rs->ti->table),
+					  &rs->journal_dev.dev);
+			if (r) {
+				rs->ti->error = "raid4/5/6 journal device lookup failure";
+				return r;
+			}
+			jdev = &rs->journal_dev.rdev;
+			md_rdev_init(jdev);
+			jdev->mddev = &rs->md;
+			jdev->bdev = rs->journal_dev.dev->bdev;
+			jdev->sectors = to_sector(i_size_read(jdev->bdev->bd_inode));
+			if (jdev->sectors < MIN_RAID456_JOURNAL_SPACE) {
+				rs->ti->error = "No space for raid4/5/6 journal";
+				return -ENOSPC;
+			}
+			rs->journal_dev.mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
+			set_bit(Journal, &jdev->flags);
+			continue;
+		}
+
+		/* "journal_mode <mode>" ("journal_dev" mandatory!) */
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_JOURNAL_MODE))) {
+			int r;
+
+			if (!test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags)) {
+				rs->ti->error = "raid4/5/6 'journal_mode' is invalid without 'journal_dev'";
+				return -EINVAL;
+			}
+			if (test_and_set_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one raid4/5/6 'journal_mode' argument allowed";
+				return -EINVAL;
+			}
+			r = dm_raid_journal_mode_to_md(arg);
+			if (r < 0) {
+				rs->ti->error = "Invalid 'journal_mode' argument";
+				return r;
+			}
+			rs->journal_dev.mode = r;
+			continue;
+		}
+
+		/*
+		 * Parameters with number values from here on.
+		 */
+		if (kstrtoint(arg, 10, &value) < 0) {
+			rs->ti->error = "Bad numerical argument given in raid params";
+			return -EINVAL;
+		}
+
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_REBUILD))) {
+			/*
+			 * "rebuild" is being passed in by userspace to provide
+			 * indexes of replaced devices and to set up additional
+			 * devices on raid level takeover.
+			 */
+			if (!__within_range(value, 0, rs->raid_disks - 1)) {
+				rs->ti->error = "Invalid rebuild index given";
+				return -EINVAL;
+			}
+
+			if (test_and_set_bit(value, (void *) rs->rebuild_disks)) {
+				rs->ti->error = "rebuild for this index already given";
+				return -EINVAL;
+			}
+
+			rd = rs->dev + value;
+			clear_bit(In_sync, &rd->rdev.flags);
+			clear_bit(Faulty, &rd->rdev.flags);
+			rd->rdev.recovery_offset = 0;
+			set_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags);
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_WRITE_MOSTLY))) {
+			if (!rt_is_raid1(rt)) {
+				rs->ti->error = "write_mostly option is only valid for RAID1";
+				return -EINVAL;
+			}
+
+			if (!__within_range(value, 0, rs->md.raid_disks - 1)) {
+				rs->ti->error = "Invalid write_mostly index given";
+				return -EINVAL;
+			}
+
+			write_mostly++;
+			set_bit(WriteMostly, &rs->dev[value].rdev.flags);
+			set_bit(__CTR_FLAG_WRITE_MOSTLY, &rs->ctr_flags);
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MAX_WRITE_BEHIND))) {
+			if (!rt_is_raid1(rt)) {
+				rs->ti->error = "max_write_behind option is only valid for RAID1";
+				return -EINVAL;
+			}
+
+			if (test_and_set_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags)) {
+				rs->ti->error = "Only one max_write_behind argument pair allowed";
+				return -EINVAL;
+			}
+
+			/*
+			 * In device-mapper, we specify things in sectors, but
+			 * MD records this value in kB
+			 */
+			if (value < 0 || value / 2 > COUNTER_MAX) {
+				rs->ti->error = "Max write-behind limit out of range";
+				return -EINVAL;
+			}
+
+			rs->md.bitmap_info.max_write_behind = value / 2;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DAEMON_SLEEP))) {
+			if (test_and_set_bit(__CTR_FLAG_DAEMON_SLEEP, &rs->ctr_flags)) {
+				rs->ti->error = "Only one daemon_sleep argument pair allowed";
+				return -EINVAL;
+			}
+			if (value < 0) {
+				rs->ti->error = "daemon sleep period out of range";
+				return -EINVAL;
+			}
+			rs->md.bitmap_info.daemon_sleep = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DATA_OFFSET))) {
+			/* Userspace passes new data_offset after having extended the the data image LV */
+			if (test_and_set_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
+				rs->ti->error = "Only one data_offset argument pair allowed";
+				return -EINVAL;
+			}
+			/* Ensure sensible data offset */
+			if (value < 0 ||
+			    (value && (value < MIN_FREE_RESHAPE_SPACE || value % to_sector(PAGE_SIZE)))) {
+				rs->ti->error = "Bogus data_offset value";
+				return -EINVAL;
+			}
+			rs->data_offset = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DELTA_DISKS))) {
+			/* Define the +/-# of disks to add to/remove from the given raid set */
+			if (test_and_set_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags)) {
+				rs->ti->error = "Only one delta_disks argument pair allowed";
+				return -EINVAL;
+			}
+			/* Ensure MAX_RAID_DEVICES and raid type minimal_devs! */
+			if (!__within_range(abs(value), 1, MAX_RAID_DEVICES - rt->minimal_devs)) {
+				rs->ti->error = "Too many delta_disk requested";
+				return -EINVAL;
+			}
+
+			rs->delta_disks = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_STRIPE_CACHE))) {
+			if (test_and_set_bit(__CTR_FLAG_STRIPE_CACHE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one stripe_cache argument pair allowed";
+				return -EINVAL;
+			}
+
+			if (!rt_is_raid456(rt)) {
+				rs->ti->error = "Inappropriate argument: stripe_cache";
+				return -EINVAL;
+			}
+
+			if (value < 0) {
+				rs->ti->error = "Bogus stripe cache entries value";
+				return -EINVAL;
+			}
+			rs->stripe_cache_entries = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MIN_RECOVERY_RATE))) {
+			if (test_and_set_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one min_recovery_rate argument pair allowed";
+				return -EINVAL;
+			}
+
+			if (value < 0) {
+				rs->ti->error = "min_recovery_rate out of range";
+				return -EINVAL;
+			}
+			rs->md.sync_speed_min = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MAX_RECOVERY_RATE))) {
+			if (test_and_set_bit(__CTR_FLAG_MAX_RECOVERY_RATE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one max_recovery_rate argument pair allowed";
+				return -EINVAL;
+			}
+
+			if (value < 0) {
+				rs->ti->error = "max_recovery_rate out of range";
+				return -EINVAL;
+			}
+			rs->md.sync_speed_max = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_REGION_SIZE))) {
+			if (test_and_set_bit(__CTR_FLAG_REGION_SIZE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one region_size argument pair allowed";
+				return -EINVAL;
+			}
+
+			region_size = value;
+			rs->requested_bitmap_chunk_sectors = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_COPIES))) {
+			if (test_and_set_bit(__CTR_FLAG_RAID10_COPIES, &rs->ctr_flags)) {
+				rs->ti->error = "Only one raid10_copies argument pair allowed";
+				return -EINVAL;
+			}
+
+			if (!__within_range(value, 2, rs->md.raid_disks)) {
+				rs->ti->error = "Bad value for 'raid10_copies'";
+				return -EINVAL;
+			}
+
+			raid10_copies = value;
+		} else {
+			DMERR("Unable to parse RAID parameter: %s", key);
+			rs->ti->error = "Unable to parse RAID parameter";
+			return -EINVAL;
+		}
+	}
+
+	if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) &&
+	    test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
+		rs->ti->error = "sync and nosync are mutually exclusive";
+		return -EINVAL;
+	}
+
+	if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags) &&
+	    (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) ||
+	     test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))) {
+		rs->ti->error = "sync/nosync and rebuild are mutually exclusive";
+		return -EINVAL;
+	}
+
+	if (write_mostly >= rs->md.raid_disks) {
+		rs->ti->error = "Can't set all raid1 devices to write_mostly";
+		return -EINVAL;
+	}
+
+	if (rs->md.sync_speed_max &&
+	    rs->md.sync_speed_min > rs->md.sync_speed_max) {
+		rs->ti->error = "Bogus recovery rates";
+		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 (rt_is_raid10(rt)) {
+		if (raid10_copies > rs->md.raid_disks) {
+			rs->ti->error = "Not enough devices to satisfy specification";
+			return -EINVAL;
+		}
+
+		rs->md.new_layout = raid10_format_to_md_layout(rs, raid10_format, raid10_copies);
+		if (rs->md.new_layout < 0) {
+			rs->ti->error = "Error getting raid10 format";
+			return rs->md.new_layout;
+		}
+
+		rt = get_raid_type_by_ll(10, rs->md.new_layout);
+		if (!rt) {
+			rs->ti->error = "Failed to recognize new raid10 layout";
+			return -EINVAL;
+		}
+
+		if ((rt->algorithm == ALGORITHM_RAID10_DEFAULT ||
+		     rt->algorithm == ALGORITHM_RAID10_NEAR) &&
+		    test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags)) {
+			rs->ti->error = "RAID10 format 'near' and 'raid10_use_near_sets' are incompatible";
+			return -EINVAL;
+		}
+	}
+
+	rs->raid10_copies = raid10_copies;
+
+	/* Assume there are no metadata devices until the drives are parsed */
+	rs->md.persistent = 0;
+	rs->md.external = 1;
+
+	/* Check, if any invalid ctr arguments have been passed in for the raid level */
+	return rs_check_for_valid_flags(rs);
+}
+
+/* Set raid4/5/6 cache size */
+static int rs_set_raid456_stripe_cache(struct raid_set *rs)
+{
+	int r;
+	struct r5conf *conf;
+	struct mddev *mddev = &rs->md;
+	uint32_t min_stripes = max(mddev->chunk_sectors, mddev->new_chunk_sectors) / 2;
+	uint32_t nr_stripes = rs->stripe_cache_entries;
+
+	if (!rt_is_raid456(rs->raid_type)) {
+		rs->ti->error = "Inappropriate raid level; cannot change stripe_cache size";
+		return -EINVAL;
+	}
+
+	if (nr_stripes < min_stripes) {
+		DMINFO("Adjusting requested %u stripe cache entries to %u to suit stripe size",
+		       nr_stripes, min_stripes);
+		nr_stripes = min_stripes;
+	}
+
+	conf = mddev->private;
+	if (!conf) {
+		rs->ti->error = "Cannot change stripe_cache size on inactive RAID set";
+		return -EINVAL;
+	}
+
+	/* Try setting number of stripes in raid456 stripe cache */
+	if (conf->min_nr_stripes != nr_stripes) {
+		r = raid5_set_cache_size(mddev, nr_stripes);
+		if (r) {
+			rs->ti->error = "Failed to set raid4/5/6 stripe cache size";
+			return r;
+		}
+
+		DMINFO("%u stripe cache entries", nr_stripes);
+	}
+
+	return 0;
+}
+
+/* Return # of data stripes as kept in mddev as of @rs (i.e. as of superblock) */
+static unsigned int mddev_data_stripes(struct raid_set *rs)
+{
+	return rs->md.raid_disks - rs->raid_type->parity_devs;
+}
+
+/* Return # of data stripes of @rs (i.e. as of ctr) */
+static unsigned int rs_data_stripes(struct raid_set *rs)
+{
+	return rs->raid_disks - rs->raid_type->parity_devs;
+}
+
+/*
+ * Retrieve rdev->sectors from any valid raid device of @rs
+ * to allow userpace to pass in arbitray "- -" device tupples.
+ */
+static sector_t __rdev_sectors(struct raid_set *rs)
+{
+	int i;
+
+	for (i = 0; i < rs->md.raid_disks; i++) {
+		struct md_rdev *rdev = &rs->dev[i].rdev;
+
+		if (!test_bit(Journal, &rdev->flags) &&
+		    rdev->bdev && rdev->sectors)
+			return rdev->sectors;
+	}
+
+	return 0;
+}
+
+/* Check that calculated dev_sectors fits all component devices. */
+static int _check_data_dev_sectors(struct raid_set *rs)
+{
+	sector_t ds = ~0;
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, &rs->md)
+		if (!test_bit(Journal, &rdev->flags) && rdev->bdev) {
+			ds = min(ds, to_sector(i_size_read(rdev->bdev->bd_inode)));
+			if (ds < rs->md.dev_sectors) {
+				rs->ti->error = "Component device(s) too small";
+				return -EINVAL;
+			}
+		}
+
+	return 0;
+}
+
+/* Calculate the sectors per device and per array used for @rs */
+static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
+{
+	int delta_disks;
+	unsigned int data_stripes;
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *rdev;
+	sector_t array_sectors = rs->ti->len, dev_sectors = rs->ti->len;
+
+	if (use_mddev) {
+		delta_disks = mddev->delta_disks;
+		data_stripes = mddev_data_stripes(rs);
+	} else {
+		delta_disks = rs->delta_disks;
+		data_stripes = rs_data_stripes(rs);
+	}
+
+	/* Special raid1 case w/o delta_disks support (yet) */
+	if (rt_is_raid1(rs->raid_type))
+		;
+	else if (rt_is_raid10(rs->raid_type)) {
+		if (rs->raid10_copies < 2 ||
+		    delta_disks < 0) {
+			rs->ti->error = "Bogus raid10 data copies or delta disks";
+			return -EINVAL;
+		}
+
+		dev_sectors *= rs->raid10_copies;
+		if (sector_div(dev_sectors, data_stripes))
+			goto bad;
+
+		array_sectors = (data_stripes + delta_disks) * dev_sectors;
+		if (sector_div(array_sectors, rs->raid10_copies))
+			goto bad;
+
+	} else if (sector_div(dev_sectors, data_stripes))
+		goto bad;
+
+	else
+		/* Striped layouts */
+		array_sectors = (data_stripes + delta_disks) * dev_sectors;
+
+	rdev_for_each(rdev, mddev)
+		if (!test_bit(Journal, &rdev->flags))
+			rdev->sectors = dev_sectors;
+
+	mddev->array_sectors = array_sectors;
+	mddev->dev_sectors = dev_sectors;
+
+	return _check_data_dev_sectors(rs);
+bad:
+	rs->ti->error = "Target length not divisible by number of data devices";
+	return -EINVAL;
+}
+
+/* Setup recovery on @rs */
+static void __rs_setup_recovery(struct raid_set *rs, sector_t dev_sectors)
+{
+	/* raid0 does not recover */
+	if (rs_is_raid0(rs))
+		rs->md.recovery_cp = MaxSector;
+	/*
+	 * A raid6 set has to be recovered either
+	 * completely or for the grown part to
+	 * ensure proper parity and Q-Syndrome
+	 */
+	else if (rs_is_raid6(rs))
+		rs->md.recovery_cp = dev_sectors;
+	/*
+	 * Other raid set types may skip recovery
+	 * depending on the 'nosync' flag.
+	 */
+	else
+		rs->md.recovery_cp = test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)
+				     ? MaxSector : dev_sectors;
+}
+
+/* Setup recovery on @rs based on raid type, device size and 'nosync' flag */
+static void rs_setup_recovery(struct raid_set *rs, sector_t dev_sectors)
+{
+	if (!dev_sectors)
+		/* New raid set or 'sync' flag provided */
+		__rs_setup_recovery(rs, 0);
+	else if (dev_sectors == MaxSector)
+		/* Prevent recovery */
+		__rs_setup_recovery(rs, MaxSector);
+	else if (__rdev_sectors(rs) < dev_sectors)
+		/* Grown raid set */
+		__rs_setup_recovery(rs, __rdev_sectors(rs));
+	else
+		__rs_setup_recovery(rs, MaxSector);
+}
+
+static void do_table_event(struct work_struct *ws)
+{
+	struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);
+
+	smp_rmb(); /* Make sure we access most actual mddev properties */
+	if (!rs_is_reshaping(rs)) {
+		if (rs_is_raid10(rs))
+			rs_set_rdev_sectors(rs);
+		rs_set_capacity(rs);
+	}
+	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);
+}
+
+/*
+ * Make sure a valid takover (level switch) is being requested on @rs
+ *
+ * Conversions of raid sets from one MD personality to another
+ * have to conform to restrictions which are enforced here.
+ */
+static int rs_check_takeover(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+	unsigned int near_copies;
+
+	if (rs->md.degraded) {
+		rs->ti->error = "Can't takeover degraded raid set";
+		return -EPERM;
+	}
+
+	if (rs_is_reshaping(rs)) {
+		rs->ti->error = "Can't takeover reshaping raid set";
+		return -EPERM;
+	}
+
+	switch (mddev->level) {
+	case 0:
+		/* raid0 -> raid1/5 with one disk */
+		if ((mddev->new_level == 1 || mddev->new_level == 5) &&
+		    mddev->raid_disks == 1)
+			return 0;
+
+		/* raid0 -> raid10 */
+		if (mddev->new_level == 10 &&
+		    !(rs->raid_disks % mddev->raid_disks))
+			return 0;
+
+		/* raid0 with multiple disks -> raid4/5/6 */
+		if (__within_range(mddev->new_level, 4, 6) &&
+		    mddev->new_layout == ALGORITHM_PARITY_N &&
+		    mddev->raid_disks > 1)
+			return 0;
+
+		break;
+
+	case 10:
+		/* Can't takeover raid10_offset! */
+		if (__is_raid10_offset(mddev->layout))
+			break;
+
+		near_copies = __raid10_near_copies(mddev->layout);
+
+		/* raid10* -> raid0 */
+		if (mddev->new_level == 0) {
+			/* Can takeover raid10_near with raid disks divisable by data copies! */
+			if (near_copies > 1 &&
+			    !(mddev->raid_disks % near_copies)) {
+				mddev->raid_disks /= near_copies;
+				mddev->delta_disks = mddev->raid_disks;
+				return 0;
+			}
+
+			/* Can takeover raid10_far */
+			if (near_copies == 1 &&
+			    __raid10_far_copies(mddev->layout) > 1)
+				return 0;
+
+			break;
+		}
+
+		/* raid10_{near,far} -> raid1 */
+		if (mddev->new_level == 1 &&
+		    max(near_copies, __raid10_far_copies(mddev->layout)) == mddev->raid_disks)
+			return 0;
+
+		/* raid10_{near,far} with 2 disks -> raid4/5 */
+		if (__within_range(mddev->new_level, 4, 5) &&
+		    mddev->raid_disks == 2)
+			return 0;
+		break;
+
+	case 1:
+		/* raid1 with 2 disks -> raid4/5 */
+		if (__within_range(mddev->new_level, 4, 5) &&
+		    mddev->raid_disks == 2) {
+			mddev->degraded = 1;
+			return 0;
+		}
+
+		/* raid1 -> raid0 */
+		if (mddev->new_level == 0 &&
+		    mddev->raid_disks == 1)
+			return 0;
+
+		/* raid1 -> raid10 */
+		if (mddev->new_level == 10)
+			return 0;
+		break;
+
+	case 4:
+		/* raid4 -> raid0 */
+		if (mddev->new_level == 0)
+			return 0;
+
+		/* raid4 -> raid1/5 with 2 disks */
+		if ((mddev->new_level == 1 || mddev->new_level == 5) &&
+		    mddev->raid_disks == 2)
+			return 0;
+
+		/* raid4 -> raid5/6 with parity N */
+		if (__within_range(mddev->new_level, 5, 6) &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+		break;
+
+	case 5:
+		/* raid5 with parity N -> raid0 */
+		if (mddev->new_level == 0 &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+
+		/* raid5 with parity N -> raid4 */
+		if (mddev->new_level == 4 &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+
+		/* raid5 with 2 disks -> raid1/4/10 */
+		if ((mddev->new_level == 1 || mddev->new_level == 4 || mddev->new_level == 10) &&
+		    mddev->raid_disks == 2)
+			return 0;
+
+		/* raid5_* ->  raid6_*_6 with Q-Syndrome N (e.g. raid5_ra -> raid6_ra_6 */
+		if (mddev->new_level == 6 &&
+		    ((mddev->layout == ALGORITHM_PARITY_N && mddev->new_layout == ALGORITHM_PARITY_N) ||
+		      __within_range(mddev->new_layout, ALGORITHM_LEFT_ASYMMETRIC_6, ALGORITHM_RIGHT_SYMMETRIC_6)))
+			return 0;
+		break;
+
+	case 6:
+		/* raid6 with parity N -> raid0 */
+		if (mddev->new_level == 0 &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+
+		/* raid6 with parity N -> raid4 */
+		if (mddev->new_level == 4 &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+
+		/* raid6_*_n with Q-Syndrome N -> raid5_* */
+		if (mddev->new_level == 5 &&
+		    ((mddev->layout == ALGORITHM_PARITY_N && mddev->new_layout == ALGORITHM_PARITY_N) ||
+		     __within_range(mddev->new_layout, ALGORITHM_LEFT_ASYMMETRIC, ALGORITHM_RIGHT_SYMMETRIC)))
+			return 0;
+
+	default:
+		break;
+	}
+
+	rs->ti->error = "takeover not possible";
+	return -EINVAL;
+}
+
+/* True if @rs requested to be taken over */
+static bool rs_takeover_requested(struct raid_set *rs)
+{
+	return rs->md.new_level != rs->md.level;
+}
+
+/* True if layout is set to reshape. */
+static bool rs_is_layout_change(struct raid_set *rs, bool use_mddev)
+{
+	return (use_mddev ? rs->md.delta_disks : rs->delta_disks) ||
+	       rs->md.new_layout != rs->md.layout ||
+	       rs->md.new_chunk_sectors != rs->md.chunk_sectors;
+}
+
+/* True if @rs is requested to reshape by ctr */
+static bool rs_reshape_requested(struct raid_set *rs)
+{
+	bool change;
+	struct mddev *mddev = &rs->md;
+
+	if (rs_takeover_requested(rs))
+		return false;
+
+	if (rs_is_raid0(rs))
+		return false;
+
+	change = rs_is_layout_change(rs, false);
+
+	/* Historical case to support raid1 reshape without delta disks */
+	if (rs_is_raid1(rs)) {
+		if (rs->delta_disks)
+			return !!rs->delta_disks;
+
+		return !change &&
+		       mddev->raid_disks != rs->raid_disks;
+	}
+
+	if (rs_is_raid10(rs))
+		return change &&
+		       !__is_raid10_far(mddev->new_layout) &&
+		       rs->delta_disks >= 0;
+
+	return change;
+}
+
+/*  Features */
+#define	FEATURE_FLAG_SUPPORTS_V190	0x1 /* Supports extended superblock */
+
+/* State flags for sb->flags */
+#define	SB_FLAG_RESHAPE_ACTIVE		0x1
+#define	SB_FLAG_RESHAPE_BACKWARDS	0x2
+
+/*
+ * 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 compat_features;	/* Used to indicate compatible features (like 1.9.0 ondisk metadata extension) */
+
+	__le32 num_devices;	/* Number of devices in this raid set. (Max 64) */
+	__le32 array_position;	/* The position of this drive in the raid set */
+
+	__le64 events;		/* Incremented by md when superblock updated */
+	__le64 failed_devices;	/* Pre 1.9.0 part of bit field of devices to */
+				/* indicate failures (see extension below) */
+
+	/*
+	 * 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 raid set
+	 * synchronisation/parity calculation.
+	 */
+	__le64 array_resync_offset;
+
+	/*
+	 * raid characteristics
+	 */
+	__le32 level;
+	__le32 layout;
+	__le32 stripe_sectors;
+
+	/********************************************************************
+	 * BELOW FOLLOW V1.9.0 EXTENSIONS TO THE PRISTINE SUPERBLOCK FORMAT!!!
+	 *
+	 * FEATURE_FLAG_SUPPORTS_V190 in the compat_features member indicates that those exist
+	 */
+
+	__le32 flags; /* Flags defining array states for reshaping */
+
+	/*
+	 * This offset tracks the progress of a raid
+	 * set reshape in order to be able to restart it
+	 */
+	__le64 reshape_position;
+
+	/*
+	 * These define the properties of the array in case of an interrupted reshape
+	 */
+	__le32 new_level;
+	__le32 new_layout;
+	__le32 new_stripe_sectors;
+	__le32 delta_disks;
+
+	__le64 array_sectors; /* Array size in sectors */
+
+	/*
+	 * Sector offsets to data on devices (reshaping).
+	 * Needed to support out of place reshaping, thus
+	 * not writing over any stripes whilst converting
+	 * them from old to new layout
+	 */
+	__le64 data_offset;
+	__le64 new_data_offset;
+
+	__le64 sectors; /* Used device size in sectors */
+
+	/*
+	 * Additonal Bit field of devices indicating failures to support
+	 * up to 256 devices with the 1.9.0 on-disk metadata format
+	 */
+	__le64 extended_failed_devices[DISKS_ARRAY_ELEMS - 1];
+
+	__le32 incompat_features;	/* Used to indicate any incompatible features */
+
+	/* Always set rest up to logical block size to 0 when writing (see get_metadata_device() below). */
+} __packed;
+
+/*
+ * Check for reshape constraints on raid set @rs:
+ *
+ * - reshape function non-existent
+ * - degraded set
+ * - ongoing recovery
+ * - ongoing reshape
+ *
+ * Returns 0 if none or -EPERM if given constraint
+ * and error message reference in @errmsg
+ */
+static int rs_check_reshape(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+
+	if (!mddev->pers || !mddev->pers->check_reshape)
+		rs->ti->error = "Reshape not supported";
+	else if (mddev->degraded)
+		rs->ti->error = "Can't reshape degraded raid set";
+	else if (rs_is_recovering(rs))
+		rs->ti->error = "Convert request on recovering raid set prohibited";
+	else if (rs_is_reshaping(rs))
+		rs->ti->error = "raid set already reshaping!";
+	else if (!(rs_is_raid1(rs) || rs_is_raid10(rs) || rs_is_raid456(rs)))
+		rs->ti->error = "Reshaping only supported for raid1/4/5/6/10";
+	else
+		return 0;
+
+	return -EPERM;
+}
+
+static int read_disk_sb(struct md_rdev *rdev, int size, bool force_reload)
+{
+	BUG_ON(!rdev->sb_page);
+
+	if (rdev->sb_loaded && !force_reload)
+		return 0;
+
+	rdev->sb_loaded = 0;
+
+	if (!sync_page_io(rdev, 0, size, rdev->sb_page, REQ_OP_READ, 0, true)) {
+		DMERR("Failed to read superblock of device at position %d",
+		      rdev->raid_disk);
+		md_error(rdev->mddev, rdev);
+		set_bit(Faulty, &rdev->flags);
+		return -EIO;
+	}
+
+	rdev->sb_loaded = 1;
+
+	return 0;
+}
+
+static void sb_retrieve_failed_devices(struct dm_raid_superblock *sb, uint64_t *failed_devices)
+{
+	failed_devices[0] = le64_to_cpu(sb->failed_devices);
+	memset(failed_devices + 1, 0, sizeof(sb->extended_failed_devices));
+
+	if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190) {
+		int i = ARRAY_SIZE(sb->extended_failed_devices);
+
+		while (i--)
+			failed_devices[i+1] = le64_to_cpu(sb->extended_failed_devices[i]);
+	}
+}
+
+static void sb_update_failed_devices(struct dm_raid_superblock *sb, uint64_t *failed_devices)
+{
+	int i = ARRAY_SIZE(sb->extended_failed_devices);
+
+	sb->failed_devices = cpu_to_le64(failed_devices[0]);
+	while (i--)
+		sb->extended_failed_devices[i] = cpu_to_le64(failed_devices[i+1]);
+}
+
+/*
+ * Synchronize the superblock members with the raid set properties
+ *
+ * All superblock data is little endian.
+ */
+static void super_sync(struct mddev *mddev, struct md_rdev *rdev)
+{
+	bool update_failed_devices = false;
+	unsigned int i;
+	uint64_t failed_devices[DISKS_ARRAY_ELEMS];
+	struct dm_raid_superblock *sb;
+	struct raid_set *rs = container_of(mddev, struct raid_set, md);
+
+	/* No metadata device, no superblock */
+	if (!rdev->meta_bdev)
+		return;
+
+	BUG_ON(!rdev->sb_page);
+
+	sb = page_address(rdev->sb_page);
+
+	sb_retrieve_failed_devices(sb, failed_devices);
+
+	for (i = 0; i < rs->raid_disks; i++)
+		if (!rs->dev[i].data_dev || test_bit(Faulty, &rs->dev[i].rdev.flags)) {
+			update_failed_devices = true;
+			set_bit(i, (void *) failed_devices);
+		}
+
+	if (update_failed_devices)
+		sb_update_failed_devices(sb, failed_devices);
+
+	sb->magic = cpu_to_le32(DM_RAID_MAGIC);
+	sb->compat_features = cpu_to_le32(FEATURE_FLAG_SUPPORTS_V190);
+
+	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->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);
+
+	/********************************************************************
+	 * BELOW FOLLOW V1.9.0 EXTENSIONS TO THE PRISTINE SUPERBLOCK FORMAT!!!
+	 *
+	 * FEATURE_FLAG_SUPPORTS_V190 in the compat_features member indicates that those exist
+	 */
+	sb->new_level = cpu_to_le32(mddev->new_level);
+	sb->new_layout = cpu_to_le32(mddev->new_layout);
+	sb->new_stripe_sectors = cpu_to_le32(mddev->new_chunk_sectors);
+
+	sb->delta_disks = cpu_to_le32(mddev->delta_disks);
+
+	smp_rmb(); /* Make sure we access most recent reshape position */
+	sb->reshape_position = cpu_to_le64(mddev->reshape_position);
+	if (le64_to_cpu(sb->reshape_position) != MaxSector) {
+		/* Flag ongoing reshape */
+		sb->flags |= cpu_to_le32(SB_FLAG_RESHAPE_ACTIVE);
+
+		if (mddev->delta_disks < 0 || mddev->reshape_backwards)
+			sb->flags |= cpu_to_le32(SB_FLAG_RESHAPE_BACKWARDS);
+	} else {
+		/* Clear reshape flags */
+		sb->flags &= ~(cpu_to_le32(SB_FLAG_RESHAPE_ACTIVE|SB_FLAG_RESHAPE_BACKWARDS));
+	}
+
+	sb->array_sectors = cpu_to_le64(mddev->array_sectors);
+	sb->data_offset = cpu_to_le64(rdev->data_offset);
+	sb->new_data_offset = cpu_to_le64(rdev->new_data_offset);
+	sb->sectors = cpu_to_le64(rdev->sectors);
+	sb->incompat_features = cpu_to_le32(0);
+
+	/* Zero out the rest of the payload after the size of the superblock */
+	memset(sb + 1, 0, rdev->sb_size - sizeof(*sb));
+}
+
+/*
+ * 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 r;
+	struct dm_raid_superblock *sb;
+	struct dm_raid_superblock *refsb;
+	uint64_t events_sb, events_refsb;
+
+	r = read_disk_sb(rdev, rdev->sb_size, false);
+	if (r)
+		return r;
+
+	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);
+		sb->compat_features = cpu_to_le32(FEATURE_FLAG_SUPPORTS_V190);
+
+		/* Force writing of superblocks to disk */
+		set_bit(MD_SB_CHANGE_DEVS, &rdev->mddev->sb_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 raid_set *rs, struct md_rdev *rdev)
+{
+	int role;
+	unsigned int d;
+	struct mddev *mddev = &rs->md;
+	uint64_t events_sb;
+	uint64_t failed_devices[DISKS_ARRAY_ELEMS];
+	struct dm_raid_superblock *sb;
+	uint32_t new_devs = 0, rebuild_and_new = 0, rebuilds = 0;
+	struct md_rdev *r;
+	struct dm_raid_superblock *sb2;
+
+	sb = page_address(rdev->sb_page);
+	events_sb = le64_to_cpu(sb->events);
+
+	/*
+	 * Initialise to 1 if this is a new superblock.
+	 */
+	mddev->events = events_sb ? : 1;
+
+	mddev->reshape_position = MaxSector;
+
+	mddev->raid_disks = le32_to_cpu(sb->num_devices);
+	mddev->level = le32_to_cpu(sb->level);
+	mddev->layout = le32_to_cpu(sb->layout);
+	mddev->chunk_sectors = le32_to_cpu(sb->stripe_sectors);
+
+	/*
+	 * Reshaping is supported, e.g. reshape_position is valid
+	 * in superblock and superblock content is authoritative.
+	 */
+	if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190) {
+		/* Superblock is authoritative wrt given raid set layout! */
+		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_stripe_sectors);
+		mddev->delta_disks = le32_to_cpu(sb->delta_disks);
+		mddev->array_sectors = le64_to_cpu(sb->array_sectors);
+
+		/* raid was reshaping and got interrupted */
+		if (le32_to_cpu(sb->flags) & SB_FLAG_RESHAPE_ACTIVE) {
+			if (test_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags)) {
+				DMERR("Reshape requested but raid set is still reshaping");
+				return -EINVAL;
+			}
+
+			if (mddev->delta_disks < 0 ||
+			    (!mddev->delta_disks && (le32_to_cpu(sb->flags) & SB_FLAG_RESHAPE_BACKWARDS)))
+				mddev->reshape_backwards = 1;
+			else
+				mddev->reshape_backwards = 0;
+
+			mddev->reshape_position = le64_to_cpu(sb->reshape_position);
+			rs->raid_type = get_raid_type_by_ll(mddev->level, mddev->layout);
+		}
+
+	} else {
+		/*
+		 * No takeover/reshaping, because we don't have the extended v1.9.0 metadata
+		 */
+		struct raid_type *rt_cur = get_raid_type_by_ll(mddev->level, mddev->layout);
+		struct raid_type *rt_new = get_raid_type_by_ll(mddev->new_level, mddev->new_layout);
+
+		if (rs_takeover_requested(rs)) {
+			if (rt_cur && rt_new)
+				DMERR("Takeover raid sets from %s to %s not yet supported by metadata. (raid level change)",
+				      rt_cur->name, rt_new->name);
+			else
+				DMERR("Takeover raid sets not yet supported by metadata. (raid level change)");
+			return -EINVAL;
+		} else if (rs_reshape_requested(rs)) {
+			DMERR("Reshaping raid sets not yet supported by metadata. (raid layout change keeping level)");
+			if (mddev->layout != mddev->new_layout) {
+				if (rt_cur && rt_new)
+					DMERR("	 current layout %s vs new layout %s",
+					      rt_cur->name, rt_new->name);
+				else
+					DMERR("	 current layout 0x%X vs new layout 0x%X",
+					      le32_to_cpu(sb->layout), mddev->new_layout);
+			}
+			if (mddev->chunk_sectors != mddev->new_chunk_sectors)
+				DMERR("	 current stripe sectors %u vs new stripe sectors %u",
+				      mddev->chunk_sectors, mddev->new_chunk_sectors);
+			if (rs->delta_disks)
+				DMERR("	 current %u disks vs new %u disks",
+				      mddev->raid_disks, mddev->raid_disks + rs->delta_disks);
+			if (rs_is_raid10(rs)) {
+				DMERR("	 Old layout: %s w/ %u copies",
+				      raid10_md_layout_to_format(mddev->layout),
+				      raid10_md_layout_to_copies(mddev->layout));
+				DMERR("	 New layout: %s w/ %u copies",
+				      raid10_md_layout_to_format(mddev->new_layout),
+				      raid10_md_layout_to_copies(mddev->new_layout));
+			}
+			return -EINVAL;
+		}
+
+		DMINFO("Discovered old metadata format; upgrading to extended metadata format");
+	}
+
+	if (!test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))
+		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 raid set 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 raid set
+	 *    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.
+	 * 3) This is/are a new device(s) being added to an old
+	 *    raid set during takeover to a higher raid level
+	 *    to provide capacity for redundancy or during reshape
+	 *    to add capacity to grow the raid set.
+	 */
+	d = 0;
+	rdev_for_each(r, mddev) {
+		if (test_bit(Journal, &rdev->flags))
+			continue;
+
+		if (test_bit(FirstUse, &r->flags))
+			new_devs++;
+
+		if (!test_bit(In_sync, &r->flags)) {
+			DMINFO("Device %d specified for rebuild; clearing superblock",
+				r->raid_disk);
+			rebuilds++;
+
+			if (test_bit(FirstUse, &r->flags))
+				rebuild_and_new++;
+		}
+
+		d++;
+	}
+
+	if (new_devs == rs->raid_disks || !rebuilds) {
+		/* Replace a broken device */
+		if (new_devs == 1 && !rs->delta_disks)
+			;
+		if (new_devs == rs->raid_disks) {
+			DMINFO("Superblocks created for new raid set");
+			set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
+		} else if (new_devs != rebuilds &&
+			   new_devs != rs->delta_disks) {
+			DMERR("New device injected into existing raid set without "
+			      "'delta_disks' or 'rebuild' parameter specified");
+			return -EINVAL;
+		}
+	} else if (new_devs && new_devs != rebuilds) {
+		DMERR("%u 'rebuild' devices cannot be injected into"
+		      " a raid set with %u other first-time devices",
+		      rebuilds, new_devs);
+		return -EINVAL;
+	} else if (rebuilds) {
+		if (rebuild_and_new && rebuilds != rebuild_and_new) {
+			DMERR("new device%s provided without 'rebuild'",
+			      new_devs > 1 ? "s" : "");
+			return -EINVAL;
+		} else if (!test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags) && rs_is_recovering(rs)) {
+			DMERR("'rebuild' specified while raid set is not in-sync (recovery_cp=%llu)",
+			      (unsigned long long) mddev->recovery_cp);
+			return -EINVAL;
+		} else if (rs_is_reshaping(rs)) {
+			DMERR("'rebuild' specified while raid set is being reshaped (reshape_position=%llu)",
+			      (unsigned long long) mddev->reshape_position);
+			return -EINVAL;
+		}
+	}
+
+	/*
+	 * Now we set the Faulty bit for those devices that are
+	 * recorded in the superblock as failed.
+	 */
+	sb_retrieve_failed_devices(sb, failed_devices);
+	rdev_for_each(r, mddev) {
+		if (test_bit(Journal, &rdev->flags) ||
+		    !r->sb_page)
+			continue;
+		sb2 = page_address(r->sb_page);
+		sb2->failed_devices = 0;
+		memset(sb2->extended_failed_devices, 0, sizeof(sb2->extended_failed_devices));
+
+		/*
+		 * 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 < 0)
+				continue;
+
+			if (role != r->raid_disk) {
+				if (rs_is_raid10(rs) && __is_raid10_near(mddev->layout)) {
+					if (mddev->raid_disks % __raid10_near_copies(mddev->layout) ||
+					    rs->raid_disks % rs->raid10_copies) {
+						rs->ti->error =
+							"Cannot change raid10 near set to odd # of devices!";
+						return -EINVAL;
+					}
+
+					sb2->array_position = cpu_to_le32(r->raid_disk);
+
+				} else if (!(rs_is_raid10(rs) && rt_is_raid0(rs->raid_type)) &&
+					   !(rs_is_raid0(rs) && rt_is_raid10(rs->raid_type)) &&
+					   !rt_is_raid1(rs->raid_type)) {
+					rs->ti->error = "Cannot change device positions in raid set";
+					return -EINVAL;
+				}
+
+				DMINFO("raid device #%d now at position #%d", role, r->raid_disk);
+			}
+
+			/*
+			 * Partial recovery is performed on
+			 * returning failed devices.
+			 */
+			if (test_bit(role, (void *) failed_devices))
+				set_bit(Faulty, &r->flags);
+		}
+	}
+
+	return 0;
+}
+
+static int super_validate(struct raid_set *rs, struct md_rdev *rdev)
+{
+	struct mddev *mddev = &rs->md;
+	struct dm_raid_superblock *sb;
+
+	if (rs_is_raid0(rs) || !rdev->sb_page || rdev->raid_disk < 0)
+		return 0;
+
+	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(rs, rdev))
+		return -EINVAL;
+
+	if (le32_to_cpu(sb->compat_features) &&
+	    le32_to_cpu(sb->compat_features) != FEATURE_FLAG_SUPPORTS_V190) {
+		rs->ti->error = "Unable to assemble array: Unknown flag(s) in compatible feature flags";
+		return -EINVAL;
+	}
+
+	if (sb->incompat_features) {
+		rs->ti->error = "Unable to assemble array: No incompatible feature flags supported yet";
+		return -EINVAL;
+	}
+
+	/* Enable bitmap creation for RAID levels != 0 */
+	mddev->bitmap_info.offset = (rt_is_raid0(rs->raid_type) || rs->journal_dev.dev) ? 0 : to_sector(4096);
+	mddev->bitmap_info.default_offset = mddev->bitmap_info.offset;
+
+	if (!test_and_clear_bit(FirstUse, &rdev->flags)) {
+		/*
+		 * Retrieve rdev size stored in superblock to be prepared for shrink.
+		 * Check extended superblock members are present otherwise the size
+		 * will not be set!
+		 */
+		if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190)
+			rdev->sectors = le64_to_cpu(sb->sectors);
+
+		rdev->recovery_offset = le64_to_cpu(sb->disk_recovery_offset);
+		if (rdev->recovery_offset == MaxSector)
+			set_bit(In_sync, &rdev->flags);
+		/*
+		 * If no reshape in progress -> we're recovering single
+		 * disk(s) and have to set the device(s) to out-of-sync
+		 */
+		else if (!rs_is_reshaping(rs))
+			clear_bit(In_sync, &rdev->flags); /* Mandatory for recovery */
+	}
+
+	/*
+	 * If a device comes back, set it as not In_sync and no longer faulty.
+	 */
+	if (test_and_clear_bit(Faulty, &rdev->flags)) {
+		rdev->recovery_offset = 0;
+		clear_bit(In_sync, &rdev->flags);
+		rdev->saved_raid_disk = rdev->raid_disk;
+	}
+
+	/* Reshape support -> restore repective data offsets */
+	rdev->data_offset = le64_to_cpu(sb->data_offset);
+	rdev->new_data_offset = le64_to_cpu(sb->new_data_offset);
+
+	return 0;
+}
+
+/*
+ * Analyse superblocks and select the freshest.
+ */
+static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
+{
+	int r;
+	struct md_rdev *rdev, *freshest;
+	struct mddev *mddev = &rs->md;
+
+	freshest = NULL;
+	rdev_for_each(rdev, mddev) {
+		if (test_bit(Journal, &rdev->flags))
+			continue;
+
+		if (!rdev->meta_bdev)
+			continue;
+
+		/* Set superblock offset/size for metadata device. */
+		rdev->sb_start = 0;
+		rdev->sb_size = bdev_logical_block_size(rdev->meta_bdev);
+		if (rdev->sb_size < sizeof(struct dm_raid_superblock) || rdev->sb_size > PAGE_SIZE) {
+			DMERR("superblock size of a logical block is no longer valid");
+			return -EINVAL;
+		}
+
+		/*
+		 * Skipping super_load due to CTR_FLAG_SYNC will cause
+		 * the array to undergo initialization again as
+		 * though it were new.	This is the intended effect
+		 * of the "sync" directive.
+		 *
+		 * With reshaping capability added, we must ensure that
+		 * that the "sync" directive is disallowed during the reshape.
+		 */
+		if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags))
+			continue;
+
+		r = super_load(rdev, freshest);
+
+		switch (r) {
+		case 1:
+			freshest = rdev;
+			break;
+		case 0:
+			break;
+		default:
+			/* This is a failure to read the superblock from the metadata device. */
+			/*
+			 * We have to keep any raid0 data/metadata device pairs or
+			 * the MD raid0 personality will fail to start the array.
+			 */
+			if (rs_is_raid0(rs))
+				continue;
+
+			/*
+			 * We keep the dm_devs to be able to emit the device tuple
+			 * properly on the table line in raid_status() (rather than
+			 * mistakenly acting as if '- -' got passed into the constructor).
+			 *
+			 * The rdev has to stay on the same_set list to allow for
+			 * the attempt to restore faulty devices on second resume.
+			 */
+			rdev->raid_disk = rdev->saved_raid_disk = -1;
+			break;
+		}
+	}
+
+	if (!freshest)
+		return 0;
+
+	/*
+	 * Validation of the freshest device provides the source of
+	 * validation for the remaining devices.
+	 */
+	rs->ti->error = "Unable to assemble array: Invalid superblocks";
+	if (super_validate(rs, freshest))
+		return -EINVAL;
+
+	if (validate_raid_redundancy(rs)) {
+		rs->ti->error = "Insufficient redundancy to activate array";
+		return -EINVAL;
+	}
+
+	rdev_for_each(rdev, mddev)
+		if (!test_bit(Journal, &rdev->flags) &&
+		    rdev != freshest &&
+		    super_validate(rs, rdev))
+			return -EINVAL;
+	return 0;
+}
+
+/*
+ * Adjust data_offset and new_data_offset on all disk members of @rs
+ * for out of place reshaping if requested by contructor
+ *
+ * We need free space at the beginning of each raid disk for forward
+ * and at the end for backward reshapes which userspace has to provide
+ * via remapping/reordering of space.
+ */
+static int rs_adjust_data_offsets(struct raid_set *rs)
+{
+	sector_t data_offset = 0, new_data_offset = 0;
+	struct md_rdev *rdev;
+
+	/* Constructor did not request data offset change */
+	if (!test_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
+		if (!rs_is_reshapable(rs))
+			goto out;
+
+		return 0;
+	}
+
+	/* HM FIXME: get In_Sync raid_dev? */
+	rdev = &rs->dev[0].rdev;
+
+	if (rs->delta_disks < 0) {
+		/*
+		 * Removing disks (reshaping backwards):
+		 *
+		 * - before reshape: data is at offset 0 and free space
+		 *		     is at end of each component LV
+		 *
+		 * - after reshape: data is at offset rs->data_offset != 0 on each component LV
+		 */
+		data_offset = 0;
+		new_data_offset = rs->data_offset;
+
+	} else if (rs->delta_disks > 0) {
+		/*
+		 * Adding disks (reshaping forwards):
+		 *
+		 * - before reshape: data is at offset rs->data_offset != 0 and
+		 *		     free space is at begin of each component LV
+		 *
+		 * - after reshape: data is at offset 0 on each component LV
+		 */
+		data_offset = rs->data_offset;
+		new_data_offset = 0;
+
+	} else {
+		/*
+		 * User space passes in 0 for data offset after having removed reshape space
+		 *
+		 * - or - (data offset != 0)
+		 *
+		 * Changing RAID layout or chunk size -> toggle offsets
+		 *
+		 * - before reshape: data is at offset rs->data_offset 0 and
+		 *		     free space is at end of each component LV
+		 *		     -or-
+		 *                   data is at offset rs->data_offset != 0 and
+		 *		     free space is at begin of each component LV
+		 *
+		 * - after reshape: data is at offset 0 if it was at offset != 0
+		 *                  or at offset != 0 if it was at offset 0
+		 *                  on each component LV
+		 *
+		 */
+		data_offset = rs->data_offset ? rdev->data_offset : 0;
+		new_data_offset = data_offset ? 0 : rs->data_offset;
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+	}
+
+	/*
+	 * Make sure we got a minimum amount of free sectors per device
+	 */
+	if (rs->data_offset &&
+	    to_sector(i_size_read(rdev->bdev->bd_inode)) - rs->md.dev_sectors < MIN_FREE_RESHAPE_SPACE) {
+		rs->ti->error = data_offset ? "No space for forward reshape" :
+					      "No space for backward reshape";
+		return -ENOSPC;
+	}
+out:
+	/*
+	 * Raise recovery_cp in case data_offset != 0 to
+	 * avoid false recovery positives in the constructor.
+	 */
+	if (rs->md.recovery_cp < rs->md.dev_sectors)
+		rs->md.recovery_cp += rs->dev[0].rdev.data_offset;
+
+	/* Adjust data offsets on all rdevs but on any raid4/5/6 journal device */
+	rdev_for_each(rdev, &rs->md) {
+		if (!test_bit(Journal, &rdev->flags)) {
+			rdev->data_offset = data_offset;
+			rdev->new_data_offset = new_data_offset;
+		}
+	}
+
+	return 0;
+}
+
+/* Userpace reordered disks -> adjust raid_disk indexes in @rs */
+static void __reorder_raid_disk_indexes(struct raid_set *rs)
+{
+	int i = 0;
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, &rs->md) {
+		if (!test_bit(Journal, &rdev->flags)) {
+			rdev->raid_disk = i++;
+			rdev->saved_raid_disk = rdev->new_raid_disk = -1;
+		}
+	}
+}
+
+/*
+ * Setup @rs for takeover by a different raid level
+ */
+static int rs_setup_takeover(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *rdev;
+	unsigned int d = mddev->raid_disks = rs->raid_disks;
+	sector_t new_data_offset = rs->dev[0].rdev.data_offset ? 0 : rs->data_offset;
+
+	if (rt_is_raid10(rs->raid_type)) {
+		if (rs_is_raid0(rs)) {
+			/* Userpace reordered disks -> adjust raid_disk indexes */
+			__reorder_raid_disk_indexes(rs);
+
+			/* raid0 -> raid10_far layout */
+			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_FAR,
+								   rs->raid10_copies);
+		} else if (rs_is_raid1(rs))
+			/* raid1 -> raid10_near layout */
+			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
+								   rs->raid_disks);
+		else
+			return -EINVAL;
+
+	}
+
+	clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
+	mddev->recovery_cp = MaxSector;
+
+	while (d--) {
+		rdev = &rs->dev[d].rdev;
+
+		if (test_bit(d, (void *) rs->rebuild_disks)) {
+			clear_bit(In_sync, &rdev->flags);
+			clear_bit(Faulty, &rdev->flags);
+			mddev->recovery_cp = rdev->recovery_offset = 0;
+			/* Bitmap has to be created when we do an "up" takeover */
+			set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
+		}
+
+		rdev->new_data_offset = new_data_offset;
+	}
+
+	return 0;
+}
+
+/* Prepare @rs for reshape */
+static int rs_prepare_reshape(struct raid_set *rs)
+{
+	bool reshape;
+	struct mddev *mddev = &rs->md;
+
+	if (rs_is_raid10(rs)) {
+		if (rs->raid_disks != mddev->raid_disks &&
+		    __is_raid10_near(mddev->layout) &&
+		    rs->raid10_copies &&
+		    rs->raid10_copies != __raid10_near_copies(mddev->layout)) {
+			/*
+			 * raid disk have to be multiple of data copies to allow this conversion,
+			 *
+			 * This is actually not a reshape it is a
+			 * rebuild of any additional mirrors per group
+			 */
+			if (rs->raid_disks % rs->raid10_copies) {
+				rs->ti->error = "Can't reshape raid10 mirror groups";
+				return -EINVAL;
+			}
+
+			/* Userpace reordered disks to add/remove mirrors -> adjust raid_disk indexes */
+			__reorder_raid_disk_indexes(rs);
+			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
+								   rs->raid10_copies);
+			mddev->new_layout = mddev->layout;
+			reshape = false;
+		} else
+			reshape = true;
+
+	} else if (rs_is_raid456(rs))
+		reshape = true;
+
+	else if (rs_is_raid1(rs)) {
+		if (rs->delta_disks) {
+			/* Process raid1 via delta_disks */
+			mddev->degraded = rs->delta_disks < 0 ? -rs->delta_disks : rs->delta_disks;
+			reshape = true;
+		} else {
+			/* Process raid1 without delta_disks */
+			mddev->raid_disks = rs->raid_disks;
+			reshape = false;
+		}
+	} else {
+		rs->ti->error = "Called with bogus raid type";
+		return -EINVAL;
+	}
+
+	if (reshape) {
+		set_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags);
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+	} else if (mddev->raid_disks < rs->raid_disks)
+		/* Create new superblocks and bitmaps, if any new disks */
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+
+	return 0;
+}
+
+/* Get reshape sectors from data_offsets or raid set */
+static sector_t _get_reshape_sectors(struct raid_set *rs)
+{
+	struct md_rdev *rdev;
+	sector_t reshape_sectors = 0;
+
+	rdev_for_each(rdev, &rs->md)
+		if (!test_bit(Journal, &rdev->flags)) {
+			reshape_sectors = (rdev->data_offset > rdev->new_data_offset) ?
+					rdev->data_offset - rdev->new_data_offset :
+					rdev->new_data_offset - rdev->data_offset;
+			break;
+		}
+
+	return max(reshape_sectors, (sector_t) rs->data_offset);
+}
+
+/*
+ * Reshape:
+ * - change raid layout
+ * - change chunk size
+ * - add disks
+ * - remove disks
+ */
+static int rs_setup_reshape(struct raid_set *rs)
+{
+	int r = 0;
+	unsigned int cur_raid_devs, d;
+	sector_t reshape_sectors = _get_reshape_sectors(rs);
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *rdev;
+
+	mddev->delta_disks = rs->delta_disks;
+	cur_raid_devs = mddev->raid_disks;
+
+	/* Ignore impossible layout change whilst adding/removing disks */
+	if (mddev->delta_disks &&
+	    mddev->layout != mddev->new_layout) {
+		DMINFO("Ignoring invalid layout change with delta_disks=%d", rs->delta_disks);
+		mddev->new_layout = mddev->layout;
+	}
+
+	/*
+	 * Adjust array size:
+	 *
+	 * - in case of adding disk(s), array size has
+	 *   to grow after the disk adding reshape,
+	 *   which'll hapen in the event handler;
+	 *   reshape will happen forward, so space has to
+	 *   be available at the beginning of each disk
+	 *
+	 * - in case of removing disk(s), array size
+	 *   has to shrink before starting the reshape,
+	 *   which'll happen here;
+	 *   reshape will happen backward, so space has to
+	 *   be available at the end of each disk
+	 *
+	 * - data_offset and new_data_offset are
+	 *   adjusted for aforementioned out of place
+	 *   reshaping based on userspace passing in
+	 *   the "data_offset <sectors>" key/value
+	 *   pair via the constructor
+	 */
+
+	/* Add disk(s) */
+	if (rs->delta_disks > 0) {
+		/* Prepare disks for check in raid4/5/6/10 {check|start}_reshape */
+		for (d = cur_raid_devs; d < rs->raid_disks; d++) {
+			rdev = &rs->dev[d].rdev;
+			clear_bit(In_sync, &rdev->flags);
+
+			/*
+			 * save_raid_disk needs to be -1, or recovery_offset will be set to 0
+			 * by md, which'll store that erroneously in the superblock on reshape
+			 */
+			rdev->saved_raid_disk = -1;
+			rdev->raid_disk = d;
+
+			rdev->sectors = mddev->dev_sectors;
+			rdev->recovery_offset = rs_is_raid1(rs) ? 0 : MaxSector;
+		}
+
+		mddev->reshape_backwards = 0; /* adding disk(s) -> forward reshape */
+
+	/* Remove disk(s) */
+	} else if (rs->delta_disks < 0) {
+		r = rs_set_dev_and_array_sectors(rs, true);
+		mddev->reshape_backwards = 1; /* removing disk(s) -> backward reshape */
+
+	/* Change layout and/or chunk size */
+	} else {
+		/*
+		 * Reshape layout (e.g. raid5_ls -> raid5_n) and/or chunk size:
+		 *
+		 * keeping number of disks and do layout change ->
+		 *
+		 * toggle reshape_backward depending on data_offset:
+		 *
+		 * - free space upfront -> reshape forward
+		 *
+		 * - free space at the end -> reshape backward
+		 *
+		 *
+		 * This utilizes free reshape space avoiding the need
+		 * for userspace to move (parts of) LV segments in
+		 * case of layout/chunksize change  (for disk
+		 * adding/removing reshape space has to be at
+		 * the proper address (see above with delta_disks):
+		 *
+		 * add disk(s)   -> begin
+		 * remove disk(s)-> end
+		 */
+		mddev->reshape_backwards = rs->dev[0].rdev.data_offset ? 0 : 1;
+	}
+
+	/*
+	 * Adjust device size for forward reshape
+	 * because md_finish_reshape() reduces it.
+	 */
+	if (!mddev->reshape_backwards)
+		rdev_for_each(rdev, &rs->md)
+			if (!test_bit(Journal, &rdev->flags))
+				rdev->sectors += reshape_sectors;
+
+	return r;
+}
+
+/*
+ * If the md resync thread has updated superblock with max reshape position
+ * at the end of a reshape but not (yet) reset the layout configuration
+ * changes -> reset the latter.
+ */
+static void rs_reset_inconclusive_reshape(struct raid_set *rs)
+{
+	if (!rs_is_reshaping(rs) && rs_is_layout_change(rs, true)) {
+		rs_set_cur(rs);
+		rs->md.delta_disks = 0;
+		rs->md.reshape_backwards = 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 raid_set *rs)
+{
+	int i;
+	bool raid456;
+	struct dm_target *ti = rs->ti;
+
+	/*
+	 * XXX: RAID level 4,5,6 require zeroing for safety.
+	 */
+	raid456 = rs_is_raid456(rs);
+
+	for (i = 0; i < rs->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 (!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;
+			}
+		}
+	}
+
+	/*
+	 * RAID1 and RAID10 personalities require bio splitting,
+	 * RAID0/4/5/6 don't and process large discard bios properly.
+	 */
+	ti->split_discard_bios = !!(rs_is_raid1(rs) || rs_is_raid10(rs));
+	ti->num_discard_bios = 1;
+}
+
+/*
+ * Construct a RAID0/1/10/4/5/6 mapping:
+ * Args:
+ *	<raid_type> <#raid_params> <raid_params>{0,}	\
+ *	<#raid_devs> [<meta_dev1> <dev1>]{1,}
+ *
+ * <raid_params> varies by <raid_type>.	 See 'parse_raid_params' for
+ * details on possible <raid_params>.
+ *
+ * Userspace is free to initialize the metadata devices, hence the superblocks to
+ * enforce recreation based on the passed in table parameters.
+ *
+ */
+static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+	int r;
+	bool resize = false;
+	struct raid_type *rt;
+	unsigned int num_raid_params, num_raid_devs;
+	sector_t calculated_dev_sectors, rdev_sectors, reshape_sectors;
+	struct raid_set *rs = NULL;
+	const char *arg;
+	struct rs_layout rs_layout;
+	struct dm_arg_set as = { argc, argv }, as_nrd;
+	struct dm_arg _args[] = {
+		{ 0, as.argc, "Cannot understand number of raid parameters" },
+		{ 1, 254, "Cannot understand number of raid devices parameters" }
+	};
+
+	/* Must have <raid_type> */
+	arg = dm_shift_arg(&as);
+	if (!arg) {
+		ti->error = "No arguments";
+		return -EINVAL;
+	}
+
+	rt = get_raid_type(arg);
+	if (!rt) {
+		ti->error = "Unrecognised raid_type";
+		return -EINVAL;
+	}
+
+	/* Must have <#raid_params> */
+	if (dm_read_arg_group(_args, &as, &num_raid_params, &ti->error))
+		return -EINVAL;
+
+	/* number of raid device tupples <meta_dev data_dev> */
+	as_nrd = as;
+	dm_consume_args(&as_nrd, num_raid_params);
+	_args[1].max = (as_nrd.argc - 1) / 2;
+	if (dm_read_arg(_args + 1, &as_nrd, &num_raid_devs, &ti->error))
+		return -EINVAL;
+
+	if (!__within_range(num_raid_devs, 1, MAX_RAID_DEVICES)) {
+		ti->error = "Invalid number of supplied raid devices";
+		return -EINVAL;
+	}
+
+	rs = raid_set_alloc(ti, rt, num_raid_devs);
+	if (IS_ERR(rs))
+		return PTR_ERR(rs);
+
+	r = parse_raid_params(rs, &as, num_raid_params);
+	if (r)
+		goto bad;
+
+	r = parse_dev_params(rs, &as);
+	if (r)
+		goto bad;
+
+	rs->md.sync_super = super_sync;
+
+	/*
+	 * Calculate ctr requested array and device sizes to allow
+	 * for superblock analysis needing device sizes defined.
+	 *
+	 * Any existing superblock will overwrite the array and device sizes
+	 */
+	r = rs_set_dev_and_array_sectors(rs, false);
+	if (r)
+		goto bad;
+
+	calculated_dev_sectors = rs->md.dev_sectors;
+
+	/*
+	 * Backup any new raid set level, layout, ...
+	 * requested to be able to compare to superblock
+	 * members for conversion decisions.
+	 */
+	rs_config_backup(rs, &rs_layout);
+
+	r = analyse_superblocks(ti, rs);
+	if (r)
+		goto bad;
+
+	rdev_sectors = __rdev_sectors(rs);
+	if (!rdev_sectors) {
+		ti->error = "Invalid rdev size";
+		r = -EINVAL;
+		goto bad;
+	}
+
+
+	reshape_sectors = _get_reshape_sectors(rs);
+	if (calculated_dev_sectors != rdev_sectors)
+		resize = calculated_dev_sectors != (reshape_sectors ? rdev_sectors - reshape_sectors : rdev_sectors);
+
+	INIT_WORK(&rs->md.event_work, do_table_event);
+	ti->private = rs;
+	ti->num_flush_bios = 1;
+
+	/* Restore any requested new layout for conversion decision */
+	rs_config_restore(rs, &rs_layout);
+
+	/*
+	 * Now that we have any superblock metadata available,
+	 * check for new, recovering, reshaping, to be taken over,
+	 * to be reshaped or an existing, unchanged raid set to
+	 * run in sequence.
+	 */
+	if (test_bit(MD_ARRAY_FIRST_USE, &rs->md.flags)) {
+		/* A new raid6 set has to be recovered to ensure proper parity and Q-Syndrome */
+		if (rs_is_raid6(rs) &&
+		    test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
+			ti->error = "'nosync' not allowed for new raid6 set";
+			r = -EINVAL;
+			goto bad;
+		}
+		rs_setup_recovery(rs, 0);
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+		rs_set_new(rs);
+	} else if (rs_is_recovering(rs)) {
+		/* Rebuild particular devices */
+		if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags)) {
+			set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+			rs_setup_recovery(rs, MaxSector);
+		}
+		/* A recovering raid set may be resized */
+		; /* skip setup rs */
+	} else if (rs_is_reshaping(rs)) {
+		/* Have to reject size change request during reshape */
+		if (resize) {
+			ti->error = "Can't resize a reshaping raid set";
+			r = -EPERM;
+			goto bad;
+		}
+		/* skip setup rs */
+	} else if (rs_takeover_requested(rs)) {
+		if (rs_is_reshaping(rs)) {
+			ti->error = "Can't takeover a reshaping raid set";
+			r = -EPERM;
+			goto bad;
+		}
+
+		/* We can't takeover a journaled raid4/5/6 */
+		if (test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags)) {
+			ti->error = "Can't takeover a journaled raid4/5/6 set";
+			r = -EPERM;
+			goto bad;
+		}
+
+		/*
+		 * If a takeover is needed, userspace sets any additional
+		 * devices to rebuild and we can check for a valid request here.
+		 *
+		 * If acceptible, set the level to the new requested
+		 * one, prohibit requesting recovery, allow the raid
+		 * set to run and store superblocks during resume.
+		 */
+		r = rs_check_takeover(rs);
+		if (r)
+			goto bad;
+
+		r = rs_setup_takeover(rs);
+		if (r)
+			goto bad;
+
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+		/* Takeover ain't recovery, so disable recovery */
+		rs_setup_recovery(rs, MaxSector);
+		rs_set_new(rs);
+	} else if (rs_reshape_requested(rs)) {
+		/*
+		 * No need to check for 'ongoing' takeover here, because takeover
+		 * is an instant operation as oposed to an ongoing reshape.
+		 */
+
+		/* We can't reshape a journaled raid4/5/6 */
+		if (test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags)) {
+			ti->error = "Can't reshape a journaled raid4/5/6 set";
+			r = -EPERM;
+			goto bad;
+		}
+
+		/* Out-of-place space has to be available to allow for a reshape unless raid1! */
+		if (reshape_sectors || rs_is_raid1(rs)) {
+			/*
+			  * We can only prepare for a reshape here, because the
+			  * raid set needs to run to provide the repective reshape
+			  * check functions via its MD personality instance.
+			  *
+			  * So do the reshape check after md_run() succeeded.
+			  */
+			r = rs_prepare_reshape(rs);
+			if (r)
+				goto bad;
+
+			/* Reshaping ain't recovery, so disable recovery */
+			rs_setup_recovery(rs, MaxSector);
+		}
+		rs_set_cur(rs);
+	} else {
+		/* May not set recovery when a device rebuild is requested */
+		if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags)) {
+			rs_setup_recovery(rs, MaxSector);
+			set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+		} else
+			rs_setup_recovery(rs, test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) ?
+					      0 : (resize ? calculated_dev_sectors : MaxSector));
+		rs_set_cur(rs);
+	}
+
+	/* If constructor requested it, change data and new_data offsets */
+	r = rs_adjust_data_offsets(rs);
+	if (r)
+		goto bad;
+
+	/* Catch any inconclusive reshape superblock content. */
+	rs_reset_inconclusive_reshape(rs);
+
+	/* Start raid set read-only and assumed clean to change in raid_resume() */
+	rs->md.ro = 1;
+	rs->md.in_sync = 1;
+
+	/* Keep array frozen until resume. */
+	set_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
+
+	/* Has to be held on running the array */
+	mddev_lock_nointr(&rs->md);
+	r = md_run(&rs->md);
+	rs->md.in_sync = 0; /* Assume already marked dirty */
+	if (r) {
+		ti->error = "Failed to run raid array";
+		mddev_unlock(&rs->md);
+		goto bad;
+	}
+
+	r = md_start(&rs->md);
+	if (r) {
+		ti->error = "Failed to start raid array";
+		mddev_unlock(&rs->md);
+		goto bad_md_start;
+	}
+
+	rs->callbacks.congested_fn = raid_is_congested;
+	dm_table_add_target_callbacks(ti->table, &rs->callbacks);
+
+	/* If raid4/5/6 journal mode explicitly requested (only possible with journal dev) -> set it */
+	if (test_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags)) {
+		r = r5c_journal_mode_set(&rs->md, rs->journal_dev.mode);
+		if (r) {
+			ti->error = "Failed to set raid4/5/6 journal mode";
+			mddev_unlock(&rs->md);
+			goto bad_journal_mode_set;
+		}
+	}
+
+	mddev_suspend(&rs->md);
+	set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags);
+
+	/* Try to adjust the raid4/5/6 stripe cache size to the stripe size */
+	if (rs_is_raid456(rs)) {
+		r = rs_set_raid456_stripe_cache(rs);
+		if (r)
+			goto bad_stripe_cache;
+	}
+
+	/* Now do an early reshape check */
+	if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
+		r = rs_check_reshape(rs);
+		if (r)
+			goto bad_check_reshape;
+
+		/* Restore new, ctr requested layout to perform check */
+		rs_config_restore(rs, &rs_layout);
+
+		if (rs->md.pers->start_reshape) {
+			r = rs->md.pers->check_reshape(&rs->md);
+			if (r) {
+				ti->error = "Reshape check failed";
+				goto bad_check_reshape;
+			}
+		}
+	}
+
+	/* Disable/enable discard support on raid set. */
+	configure_discard_support(rs);
+
+	mddev_unlock(&rs->md);
+	return 0;
+
+bad_md_start:
+bad_journal_mode_set:
+bad_stripe_cache:
+bad_check_reshape:
+	md_stop(&rs->md);
+bad:
+	raid_set_free(rs);
+
+	return r;
+}
+
+static void raid_dtr(struct dm_target *ti)
+{
+	struct raid_set *rs = ti->private;
+
+	list_del_init(&rs->callbacks.list);
+	md_stop(&rs->md);
+	raid_set_free(rs);
+}
+
+static int raid_map(struct dm_target *ti, struct bio *bio)
+{
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
+
+	/*
+	 * If we're reshaping to add disk(s)), ti->len and
+	 * mddev->array_sectors will differ during the process
+	 * (ti->len > mddev->array_sectors), so we have to requeue
+	 * bios with addresses > mddev->array_sectors here or
+	 * there will occur accesses past EOD of the component
+	 * data images thus erroring the raid set.
+	 */
+	if (unlikely(bio_end_sector(bio) > mddev->array_sectors))
+		return DM_MAPIO_REQUEUE;
+
+	md_handle_request(mddev, bio);
+
+	return DM_MAPIO_SUBMITTED;
+}
+
+/* Return sync state string for @state */
+enum sync_state { st_frozen, st_reshape, st_resync, st_check, st_repair, st_recover, st_idle };
+static const char *sync_str(enum sync_state state)
+{
+	/* Has to be in above sync_state order! */
+	static const char *sync_strs[] = {
+		"frozen",
+		"reshape",
+		"resync",
+		"check",
+		"repair",
+		"recover",
+		"idle"
+	};
+
+	return __within_range(state, 0, ARRAY_SIZE(sync_strs) - 1) ? sync_strs[state] : "undef";
+};
+
+/* Return enum sync_state for @mddev derived from @recovery flags */
+static enum sync_state decipher_sync_action(struct mddev *mddev, unsigned long recovery)
+{
+	if (test_bit(MD_RECOVERY_FROZEN, &recovery))
+		return st_frozen;
+
+	/* The MD sync thread can be done with io or be interrupted but still be running */
+	if (!test_bit(MD_RECOVERY_DONE, &recovery) &&
+	    (test_bit(MD_RECOVERY_RUNNING, &recovery) ||
+	     (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &recovery)))) {
+		if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
+			return st_reshape;
+
+		if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
+			if (!test_bit(MD_RECOVERY_REQUESTED, &recovery))
+				return st_resync;
+			if (test_bit(MD_RECOVERY_CHECK, &recovery))
+				return st_check;
+			return st_repair;
+		}
+
+		if (test_bit(MD_RECOVERY_RECOVER, &recovery))
+			return st_recover;
+
+		if (mddev->reshape_position != MaxSector)
+			return st_reshape;
+	}
+
+	return st_idle;
+}
+
+/*
+ * Return status string for @rdev
+ *
+ * Status characters:
+ *
+ *  'D' = Dead/Failed raid set component or raid4/5/6 journal device
+ *  'a' = Alive but not in-sync raid set component _or_ alive raid4/5/6 'write_back' journal device
+ *  'A' = Alive and in-sync raid set component _or_ alive raid4/5/6 'write_through' journal device
+ *  '-' = Non-existing device (i.e. uspace passed '- -' into the ctr)
+ */
+static const char *__raid_dev_status(struct raid_set *rs, struct md_rdev *rdev)
+{
+	if (!rdev->bdev)
+		return "-";
+	else if (test_bit(Faulty, &rdev->flags))
+		return "D";
+	else if (test_bit(Journal, &rdev->flags))
+		return (rs->journal_dev.mode == R5C_JOURNAL_MODE_WRITE_THROUGH) ? "A" : "a";
+	else if (test_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags) ||
+		 (!test_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags) &&
+		  !test_bit(In_sync, &rdev->flags)))
+		return "a";
+	else
+		return "A";
+}
+
+/* Helper to return resync/reshape progress for @rs and runtime flags for raid set in sync / resynching */
+static sector_t rs_get_progress(struct raid_set *rs, unsigned long recovery,
+				sector_t resync_max_sectors)
+{
+	sector_t r;
+	enum sync_state state;
+	struct mddev *mddev = &rs->md;
+
+	clear_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+	clear_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);
+
+	if (rs_is_raid0(rs)) {
+		r = resync_max_sectors;
+		set_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+
+	} else {
+		state = decipher_sync_action(mddev, recovery);
+
+		if (state == st_idle && !test_bit(MD_RECOVERY_INTR, &recovery))
+			r = mddev->recovery_cp;
+		else
+			r = mddev->curr_resync_completed;
+
+		if (state == st_idle && r >= resync_max_sectors) {
+			/*
+			 * Sync complete.
+			 */
+			/* In case we have finished recovering, the array is in sync. */
+			if (test_bit(MD_RECOVERY_RECOVER, &recovery))
+				set_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+
+		} else if (state == st_recover)
+			/*
+			 * In case we are recovering, the array is not in sync
+			 * and health chars should show the recovering legs.
+			 */
+			;
+		else if (state == st_resync)
+			/*
+			 * If "resync" is occurring, the raid set
+			 * is or may be out of sync hence the health
+			 * characters shall be 'a'.
+			 */
+			set_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);
+		else if (state == st_reshape)
+			/*
+			 * If "reshape" is occurring, the raid set
+			 * is or may be out of sync hence the health
+			 * characters shall be 'a'.
+			 */
+			set_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);
+
+		else if (state == st_check || state == st_repair)
+			/*
+			 * If "check" or "repair" is occurring, the raid set has
+			 * undergone an initial sync and the health characters
+			 * should not be 'a' anymore.
+			 */
+			set_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+
+		else {
+			struct md_rdev *rdev;
+
+			/*
+			 * We are idle and recovery is needed, prevent 'A' chars race
+			 * caused by components still set to in-sync by constructor.
+			 */
+			if (test_bit(MD_RECOVERY_NEEDED, &recovery))
+				set_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);
+
+			/*
+			 * The raid set may be doing an initial sync, or it may
+			 * be rebuilding individual components.	 If all the
+			 * devices are In_sync, then it is the raid set that is
+			 * being initialized.
+			 */
+			set_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+			rdev_for_each(rdev, mddev)
+				if (!test_bit(Journal, &rdev->flags) &&
+				    !test_bit(In_sync, &rdev->flags)) {
+					clear_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+					break;
+				}
+		}
+	}
+
+	return min(r, resync_max_sectors);
+}
+
+/* Helper to return @dev name or "-" if !@dev */
+static const char *__get_dev_name(struct dm_dev *dev)
+{
+	return dev ? dev->name : "-";
+}
+
+static void raid_status(struct dm_target *ti, status_type_t type,
+			unsigned int status_flags, char *result, unsigned int maxlen)
+{
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
+	struct r5conf *conf = mddev->private;
+	int i, max_nr_stripes = conf ? conf->max_nr_stripes : 0;
+	unsigned long recovery;
+	unsigned int raid_param_cnt = 1; /* at least 1 for chunksize */
+	unsigned int sz = 0;
+	unsigned int rebuild_disks;
+	unsigned int write_mostly_params = 0;
+	sector_t progress, resync_max_sectors, resync_mismatches;
+	const char *sync_action;
+	struct raid_type *rt;
+
+	switch (type) {
+	case STATUSTYPE_INFO:
+		/* *Should* always succeed */
+		rt = get_raid_type_by_ll(mddev->new_level, mddev->new_layout);
+		if (!rt)
+			return;
+
+		DMEMIT("%s %d ", rt->name, mddev->raid_disks);
+
+		/* Access most recent mddev properties for status output */
+		smp_rmb();
+		recovery = rs->md.recovery;
+		/* Get sensible max sectors even if raid set not yet started */
+		resync_max_sectors = test_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags) ?
+				      mddev->resync_max_sectors : mddev->dev_sectors;
+		progress = rs_get_progress(rs, recovery, resync_max_sectors);
+		resync_mismatches = (mddev->last_sync_action && !strcasecmp(mddev->last_sync_action, "check")) ?
+				    atomic64_read(&mddev->resync_mismatches) : 0;
+		sync_action = sync_str(decipher_sync_action(&rs->md, recovery));
+
+		/* HM FIXME: do we want another state char for raid0? It shows 'D'/'A'/'-' now */
+		for (i = 0; i < rs->raid_disks; i++)
+			DMEMIT(__raid_dev_status(rs, &rs->dev[i].rdev));
+
+		/*
+		 * In-sync/Reshape ratio:
+		 *  The in-sync ratio shows the progress of:
+		 *   - Initializing the raid set
+		 *   - Rebuilding a subset of devices of the raid set
+		 *  The user can distinguish between the two by referring
+		 *  to the status characters.
+		 *
+		 *  The reshape ratio shows the progress of
+		 *  changing the raid layout or the number of
+		 *  disks of a raid set
+		 */
+		DMEMIT(" %llu/%llu", (unsigned long long) progress,
+				     (unsigned long long) resync_max_sectors);
+
+		/*
+		 * v1.5.0+:
+		 *
+		 * Sync action:
+		 *   See Documentation/device-mapper/dm-raid.txt for
+		 *   information on each of these states.
+		 */
+		DMEMIT(" %s", sync_action);
+
+		/*
+		 * v1.5.0+:
+		 *
+		 * resync_mismatches/mismatch_cnt
+		 *   This field shows the number of discrepancies found when
+		 *   performing a "check" of the raid set.
+		 */
+		DMEMIT(" %llu", (unsigned long long) resync_mismatches);
+
+		/*
+		 * v1.9.0+:
+		 *
+		 * data_offset (needed for out of space reshaping)
+		 *   This field shows the data offset into the data
+		 *   image LV where the first stripes data starts.
+		 *
+		 * We keep data_offset equal on all raid disks of the set,
+		 * so retrieving it from the first raid disk is sufficient.
+		 */
+		DMEMIT(" %llu", (unsigned long long) rs->dev[0].rdev.data_offset);
+
+		/*
+		 * v1.10.0+:
+		 */
+		DMEMIT(" %s", test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags) ?
+			      __raid_dev_status(rs, &rs->journal_dev.rdev) : "-");
+		break;
+
+	case STATUSTYPE_TABLE:
+		/* Report the table line string you would use to construct this raid set */
+
+		/* Calculate raid parameter count */
+		for (i = 0; i < rs->raid_disks; i++)
+			if (test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+				write_mostly_params += 2;
+		rebuild_disks = memweight(rs->rebuild_disks, DISKS_ARRAY_ELEMS * sizeof(*rs->rebuild_disks));
+		raid_param_cnt += rebuild_disks * 2 +
+				  write_mostly_params +
+				  hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_NO_ARGS) +
+				  hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_ONE_ARG) * 2 +
+				  (test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags) ? 2 : 0) +
+				  (test_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags) ? 2 : 0);
+
+		/* Emit table line */
+		/* This has to be in the documented order for userspace! */
+		DMEMIT("%s %u %u", rs->raid_type->name, raid_param_cnt, mddev->new_chunk_sectors);
+		if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags))
+			DMEMIT(" %s", dm_raid_arg_name_by_flag(CTR_FLAG_SYNC));
+		if (test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))
+			DMEMIT(" %s", dm_raid_arg_name_by_flag(CTR_FLAG_NOSYNC));
+		if (rebuild_disks)
+			for (i = 0; i < rs->raid_disks; i++)
+				if (test_bit(rs->dev[i].rdev.raid_disk, (void *) rs->rebuild_disks))
+					DMEMIT(" %s %u", dm_raid_arg_name_by_flag(CTR_FLAG_REBUILD),
+							 rs->dev[i].rdev.raid_disk);
+		if (test_bit(__CTR_FLAG_DAEMON_SLEEP, &rs->ctr_flags))
+			DMEMIT(" %s %lu", dm_raid_arg_name_by_flag(CTR_FLAG_DAEMON_SLEEP),
+					  mddev->bitmap_info.daemon_sleep);
+		if (test_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_MIN_RECOVERY_RATE),
+					 mddev->sync_speed_min);
+		if (test_bit(__CTR_FLAG_MAX_RECOVERY_RATE, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_MAX_RECOVERY_RATE),
+					 mddev->sync_speed_max);
+		if (write_mostly_params)
+			for (i = 0; i < rs->raid_disks; i++)
+				if (test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+					DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_WRITE_MOSTLY),
+					       rs->dev[i].rdev.raid_disk);
+		if (test_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags))
+			DMEMIT(" %s %lu", dm_raid_arg_name_by_flag(CTR_FLAG_MAX_WRITE_BEHIND),
+					  mddev->bitmap_info.max_write_behind);
+		if (test_bit(__CTR_FLAG_STRIPE_CACHE, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_STRIPE_CACHE),
+					 max_nr_stripes);
+		if (test_bit(__CTR_FLAG_REGION_SIZE, &rs->ctr_flags))
+			DMEMIT(" %s %llu", dm_raid_arg_name_by_flag(CTR_FLAG_REGION_SIZE),
+					   (unsigned long long) to_sector(mddev->bitmap_info.chunksize));
+		if (test_bit(__CTR_FLAG_RAID10_COPIES, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_COPIES),
+					 raid10_md_layout_to_copies(mddev->layout));
+		if (test_bit(__CTR_FLAG_RAID10_FORMAT, &rs->ctr_flags))
+			DMEMIT(" %s %s", dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_FORMAT),
+					 raid10_md_layout_to_format(mddev->layout));
+		if (test_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_DELTA_DISKS),
+					 max(rs->delta_disks, mddev->delta_disks));
+		if (test_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags))
+			DMEMIT(" %s %llu", dm_raid_arg_name_by_flag(CTR_FLAG_DATA_OFFSET),
+					   (unsigned long long) rs->data_offset);
+		if (test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags))
+			DMEMIT(" %s %s", dm_raid_arg_name_by_flag(CTR_FLAG_JOURNAL_DEV),
+					__get_dev_name(rs->journal_dev.dev));
+		if (test_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags))
+			DMEMIT(" %s %s", dm_raid_arg_name_by_flag(CTR_FLAG_JOURNAL_MODE),
+					 md_journal_mode_to_dm_raid(rs->journal_dev.mode));
+		DMEMIT(" %d", rs->raid_disks);
+		for (i = 0; i < rs->raid_disks; i++)
+			DMEMIT(" %s %s", __get_dev_name(rs->dev[i].meta_dev),
+					 __get_dev_name(rs->dev[i].data_dev));
+	}
+}
+
+static int raid_message(struct dm_target *ti, unsigned int argc, char **argv,
+			char *result, unsigned maxlen)
+{
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
+
+	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 (decipher_sync_action(mddev, mddev->recovery) != st_idle)
+		return -EBUSY;
+	else if (!strcasecmp(argv[0], "resync"))
+		; /* MD_RECOVERY_NEEDED set below */
+	else if (!strcasecmp(argv[0], "recover"))
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+	else {
+		if (!strcasecmp(argv[0], "check")) {
+			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+			set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+			set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+		} else if (!strcasecmp(argv[0], "repair")) {
+			set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+			set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+		} else
+			return -EINVAL;
+	}
+	if (mddev->ro == 2) {
+		/* A write to sync_action is enough to justify
+		 * canceling read-auto mode
+		 */
+		mddev->ro = 0;
+		if (!mddev->suspended && mddev->sync_thread)
+			md_wakeup_thread(mddev->sync_thread);
+	}
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	if (!mddev->suspended && mddev->thread)
+		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 int i;
+	int r = 0;
+
+	for (i = 0; !r && i < rs->md.raid_disks; i++)
+		if (rs->dev[i].data_dev)
+			r = fn(ti,
+				 rs->dev[i].data_dev,
+				 0, /* No offset on data devs */
+				 rs->md.dev_sectors,
+				 data);
+
+	return r;
+}
+
+static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+	struct raid_set *rs = ti->private;
+	unsigned int chunk_size = to_bytes(rs->md.chunk_sectors);
+
+	blk_limits_io_min(limits, chunk_size);
+	blk_limits_io_opt(limits, chunk_size * mddev_data_stripes(rs));
+}
+
+static void raid_postsuspend(struct dm_target *ti)
+{
+	struct raid_set *rs = ti->private;
+
+	if (!test_and_set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {
+		/* Writes have to be stopped before suspending to avoid deadlocks. */
+		if (!test_bit(MD_RECOVERY_FROZEN, &rs->md.recovery))
+			md_stop_writes(&rs->md);
+
+		mddev_lock_nointr(&rs->md);
+		mddev_suspend(&rs->md);
+		mddev_unlock(&rs->md);
+	}
+}
+
+static void attempt_restore_of_faulty_devices(struct raid_set *rs)
+{
+	int i;
+	uint64_t cleared_failed_devices[DISKS_ARRAY_ELEMS];
+	unsigned long flags;
+	bool cleared = false;
+	struct dm_raid_superblock *sb;
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *r;
+
+	/* RAID personalities have to provide hot add/remove methods or we need to bail out. */
+	if (!mddev->pers || !mddev->pers->hot_add_disk || !mddev->pers->hot_remove_disk)
+		return;
+
+	memset(cleared_failed_devices, 0, sizeof(cleared_failed_devices));
+
+	for (i = 0; i < mddev->raid_disks; i++) {
+		r = &rs->dev[i].rdev;
+		/* HM FIXME: enhance journal device recovery processing */
+		if (test_bit(Journal, &r->flags))
+			continue;
+
+		if (test_bit(Faulty, &r->flags) &&
+		    r->meta_bdev && !read_disk_sb(r, r->sb_size, true)) {
+			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.
+			 */
+			flags = r->flags;
+			clear_bit(In_sync, &r->flags); /* Mandatory for hot remove. */
+			if (r->raid_disk >= 0) {
+				if (mddev->pers->hot_remove_disk(mddev, r)) {
+					/* Failed to revive this device, try next */
+					r->flags = flags;
+					continue;
+				}
+			} else
+				r->raid_disk = r->saved_raid_disk = i;
+
+			clear_bit(Faulty, &r->flags);
+			clear_bit(WriteErrorSeen, &r->flags);
+
+			if (mddev->pers->hot_add_disk(mddev, r)) {
+				/* Failed to revive this device, try next */
+				r->raid_disk = r->saved_raid_disk = -1;
+				r->flags = flags;
+			} else {
+				clear_bit(In_sync, &r->flags);
+				r->recovery_offset = 0;
+				set_bit(i, (void *) cleared_failed_devices);
+				cleared = true;
+			}
+		}
+	}
+
+	/* If any failed devices could be cleared, update all sbs failed_devices bits */
+	if (cleared) {
+		uint64_t failed_devices[DISKS_ARRAY_ELEMS];
+
+		rdev_for_each(r, &rs->md) {
+			if (test_bit(Journal, &r->flags))
+				continue;
+
+			sb = page_address(r->sb_page);
+			sb_retrieve_failed_devices(sb, failed_devices);
+
+			for (i = 0; i < DISKS_ARRAY_ELEMS; i++)
+				failed_devices[i] &= ~cleared_failed_devices[i];
+
+			sb_update_failed_devices(sb, failed_devices);
+		}
+	}
+}
+
+static int __load_dirty_region_bitmap(struct raid_set *rs)
+{
+	int r = 0;
+
+	/* Try loading the bitmap unless "raid0", which does not have one */
+	if (!rs_is_raid0(rs) &&
+	    !test_and_set_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags)) {
+		r = md_bitmap_load(&rs->md);
+		if (r)
+			DMERR("Failed to load bitmap");
+	}
+
+	return r;
+}
+
+/* Enforce updating all superblocks */
+static void rs_update_sbs(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+	int ro = mddev->ro;
+
+	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+	mddev->ro = 0;
+	md_update_sb(mddev, 1);
+	mddev->ro = ro;
+}
+
+/*
+ * Reshape changes raid algorithm of @rs to new one within personality
+ * (e.g. raid6_zr -> raid6_nc), changes stripe size, adds/removes
+ * disks from a raid set thus growing/shrinking it or resizes the set
+ *
+ * Call mddev_lock_nointr() before!
+ */
+static int rs_start_reshape(struct raid_set *rs)
+{
+	int r;
+	struct mddev *mddev = &rs->md;
+	struct md_personality *pers = mddev->pers;
+
+	/* Don't allow the sync thread to work until the table gets reloaded. */
+	set_bit(MD_RECOVERY_WAIT, &mddev->recovery);
+
+	r = rs_setup_reshape(rs);
+	if (r)
+		return r;
+
+	/*
+	 * Check any reshape constraints enforced by the personalility
+	 *
+	 * May as well already kick the reshape off so that * pers->start_reshape() becomes optional.
+	 */
+	r = pers->check_reshape(mddev);
+	if (r) {
+		rs->ti->error = "pers->check_reshape() failed";
+		return r;
+	}
+
+	/*
+	 * Personality may not provide start reshape method in which
+	 * case check_reshape above has already covered everything
+	 */
+	if (pers->start_reshape) {
+		r = pers->start_reshape(mddev);
+		if (r) {
+			rs->ti->error = "pers->start_reshape() failed";
+			return r;
+		}
+	}
+
+	/*
+	 * Now reshape got set up, update superblocks to
+	 * reflect the fact so that a table reload will
+	 * access proper superblock content in the ctr.
+	 */
+	rs_update_sbs(rs);
+
+	return 0;
+}
+
+static int raid_preresume(struct dm_target *ti)
+{
+	int r;
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
+
+	/* This is a resume after a suspend of the set -> it's already started. */
+	if (test_and_set_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags))
+		return 0;
+
+	/*
+	 * The superblocks need to be updated on disk if the
+	 * array is new or new devices got added (thus zeroed
+	 * out by userspace) or __load_dirty_region_bitmap
+	 * will overwrite them in core with old data or fail.
+	 */
+	if (test_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags))
+		rs_update_sbs(rs);
+
+	/* Load the bitmap from disk unless raid0 */
+	r = __load_dirty_region_bitmap(rs);
+	if (r)
+		return r;
+
+	/* Resize bitmap to adjust to changed region size (aka MD bitmap chunksize) */
+	if (test_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags) && mddev->bitmap &&
+	    mddev->bitmap_info.chunksize != to_bytes(rs->requested_bitmap_chunk_sectors)) {
+		r = md_bitmap_resize(mddev->bitmap, mddev->dev_sectors,
+				     to_bytes(rs->requested_bitmap_chunk_sectors), 0);
+		if (r)
+			DMERR("Failed to resize bitmap");
+	}
+
+	/* Check for any resize/reshape on @rs and adjust/initiate */
+	/* Be prepared for mddev_resume() in raid_resume() */
+	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	if (mddev->recovery_cp && mddev->recovery_cp < MaxSector) {
+		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+		mddev->resync_min = mddev->recovery_cp;
+	}
+
+	/* Check for any reshape request unless new raid set */
+	if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
+		/* Initiate a reshape. */
+		rs_set_rdev_sectors(rs);
+		mddev_lock_nointr(mddev);
+		r = rs_start_reshape(rs);
+		mddev_unlock(mddev);
+		if (r)
+			DMWARN("Failed to check/start reshape, continuing without change");
+		r = 0;
+	}
+
+	return r;
+}
+
+static void raid_resume(struct dm_target *ti)
+{
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
+
+	if (test_and_set_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags)) {
+		/*
+		 * 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);
+	}
+
+	if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {
+		/* Only reduce raid set size before running a disk removing reshape. */
+		if (mddev->delta_disks < 0)
+			rs_set_capacity(rs);
+
+		mddev_lock_nointr(mddev);
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		mddev->ro = 0;
+		mddev->in_sync = 0;
+		mddev_resume(mddev);
+		mddev_unlock(mddev);
+	}
+}
+
+static struct target_type raid_target = {
+	.name = "raid",
+	.version = {1, 14, 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,
+	.postsuspend = raid_postsuspend,
+	.preresume = raid_preresume,
+	.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 " raid0/1/10/4/5/6 target");
+MODULE_ALIAS("dm-raid0");
+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_AUTHOR("Heinz Mauelshagen <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");