Quelle dm-raid.c

Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
* 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;

/*
* The following flags are used by dm-raid 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 | \
      CTR_FLAG_JOURNAL_DEV | \
      CTR_FLAG_JOURNAL_MODE)

/* 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
#define RT_FLAG_RS_GROW   8
#define RT_FLAG_RS_FROZEN  9

/* 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;

sector_t array_sectors;
sector_t dev_sectors;

/* 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[] __counted_by(raid_disks);
};

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.resync_offset < 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;
  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_and_notify(gendisk, rs->md.array_sectors);
}

/*
* 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);
}

if (mddev_init(&rs->md)) {
  kfree(rs);
  ti->error = "Cannot initialize raid context";
  return ERR_PTR(-ENOMEM);
}

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.resync_offset = 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);
}

mddev_destroy(&rs->md);
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.resync_offset) {
  /*
* 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, raid_disks;
unsigned int group_size, last_group_start;

for (i = 0; i < rs->raid_disks; i++)
  if (!test_bit(FirstUse, &rs->dev[i].rdev.flags) &&
      ((!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
*/
  raid_disks = min(rs->raid_disks, rs->md.raid_disks);
  if (__is_raid10_near(rs->md.new_layout)) {
   for (i = 0; i < 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 = (raid_disks / copies);
  last_group_start = (raid_disks / group_size) - 1;
  last_group_start *= group_size;
  for (i = 0; i < 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 = bdev_nr_sectors(jdev->bdev);
   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;
   }

   if (value < 0) {
    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 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->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, bdev_nr_sectors(rdev->bdev));
   if (ds < rs->md.dev_sectors) {
    rs->ti->error = "Component device(s) too small";
    return -EINVAL;
   }
  }

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);
}

/* Calculate the sectors per device and per array used for @rs */
static int rs_set_dev_and_array_sectors(struct raid_set *rs, sector_t sectors, bool use_mddev)
{
int delta_disks;
unsigned int data_stripes;
sector_t array_sectors = sectors, dev_sectors = sectors;
struct mddev *mddev = &rs->md;

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 - _get_reshape_sectors(rs));
  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 - _get_reshape_sectors(rs));

mddev->array_sectors = array_sectors;
mddev->dev_sectors = dev_sectors;
rs_set_rdev_sectors(rs);

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.resync_offset = 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.resync_offset = dev_sectors;
/*
* Other raid set types may skip recovery
* depending on the 'nosync' flag.
*/
else
  rs->md.resync_offset = test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)
         ? MaxSector : dev_sectors;
}

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 */

/* Only grow size resulting from added stripe(s) after reshape ended. */
if (!rs_is_reshaping(rs) &&
     rs->array_sectors > rs->md.array_sectors &&
     !rs->md.delta_disks &&
     rs->md.raid_disks == rs->raid_disks) {
  /* The raid10 personality doesn't provide proper device sizes -> correct. */
  if (rs_is_raid10(rs))
   rs_set_rdev_sectors(rs);

  rs->md.array_sectors = rs->array_sectors;
  rs_set_capacity(rs);
}

dm_table_event(rs->ti->table);
}

/*
* 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;
  break;

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 */

/*
* Additional 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, 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->resync_offset);

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;
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->resync_offset = 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,
*    resync_offset 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
*    resync_offset 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.
*/
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++;
  }
}

if (new_devs == rs->raid_disks || !rebuilds) {
  /* Replace a broken device */
  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 (resync_offset=%llu)",
         (unsigned long long) mddev->resync_offset);
   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, &r->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 on @rs unless no metadevs or raid0 or journaled raid4/5/6 set. */
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 respective 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;

/* Respect resynchronization requested with "sync" argument. */
if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags))
  set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);

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
* 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 constructor
*
* 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 &&
     bdev_nr_sectors(rdev->bdev) - 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 resync_offset in case data_offset != 0 to
* avoid false recovery positives in the constructor.
*/
if (rs->md.resync_offset < rs->md.dev_sectors)
  rs->md.resync_offset += 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->resync_offset = 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->resync_offset = 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;
}

/*
* 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 happen 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, rs->ti->len, 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++) {
  if (!rs->dev[i].rdev.bdev ||
      !bdev_max_discard_sectors(rs->dev[i].rdev.bdev))
   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;
   }
  }
}

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 sb_array_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" }
};

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, rs->ti->len, false);
if (r)
  goto bad;

/* Memorize just calculated, potentially larger sizes to grow the raid set in preresume */
rs->array_sectors = rs->md.array_sectors;
rs->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;

/* All in-core metadata now as of current superblocks after calling analyse_superblocks() */
sb_array_sectors = rs->md.array_sectors;
rdev_sectors = __rdev_sectors(rs);
if (!rdev_sectors) {
  ti->error = "Invalid rdev size";
  r = -EINVAL;
  goto bad;
}

reshape_sectors = _get_reshape_sectors(rs);
if (rs->dev_sectors != rdev_sectors) {
  resize = (rs->dev_sectors != rdev_sectors - reshape_sectors);
  if (rs->dev_sectors > rdev_sectors - reshape_sectors)
   set_bit(RT_FLAG_RS_GROW, &rs->runtime_flags);
}

INIT_WORK(&rs->md.event_work, do_table_event);
ti->private = rs;
ti->num_flush_bios = 1;
ti->needs_bio_set_dev = true;

/* 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)) {
  /* A recovering raid set may be resized */
  goto size_check;
} 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 acceptable, 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)) {
  /* Only request grow on raid set size extensions, not on reshapes. */
  clear_bit(RT_FLAG_RS_GROW, &rs->runtime_flags);

  /*
* 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 respective 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 {
size_check:
  /* May not set recovery when a device rebuild is requested */
  if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags)) {
   clear_bit(RT_FLAG_RS_GROW, &rs->runtime_flags);
   set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
   rs_setup_recovery(rs, MaxSector);
  } else if (test_bit(RT_FLAG_RS_GROW, &rs->runtime_flags)) {
   /*
* Set raid set to current size, i.e. size as of
* superblocks to grow to larger size in preresume.
*/
   r = rs_set_dev_and_array_sectors(rs, sb_array_sectors, false);
   if (r)
    goto bad;

   rs_setup_recovery(rs, rs->md.resync_offset < rs->md.dev_sectors ? rs->md.resync_offset : rs->md.dev_sectors);
  } else {
   /* This is no size change or it is shrinking, update size and record in superblocks */
   r = rs_set_dev_and_array_sectors(rs, rs->ti->len, false);
   if (r)
    goto bad;

   if (sb_array_sectors > rs->array_sectors)
    set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
  }
  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;

/* Has to be held on running the array */
mddev_suspend_and_lock_nointr(&rs->md);

/* Keep array frozen until resume. */
md_frozen_sync_thread(&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";
  goto bad_unlock;
}

/* 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";
   goto bad_unlock;
  }
}

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_unlock;
}

/* 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_unlock;

  /* 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_unlock;
   }
  }
}

/* Disable/enable discard support on raid set. */
configure_discard_support(rs);
rs->md.dm_gendisk = dm_disk(dm_table_get_md(ti->table));

mddev_unlock(&rs->md);
return 0;

bad_unlock:
md_stop(&rs->md);
mddev_unlock(&rs->md);
bad:
raid_set_free(rs);

return r;
}

static void raid_dtr(struct dm_target *ti)
{
struct raid_set *rs = ti->private;

mddev_lock_nointr(&rs->md);
md_stop(&rs->md);
rs->md.dm_gendisk = NULL;
mddev_unlock(&rs->md);

if (work_pending(&rs->md.event_work))
  flush_work(&rs->md.event_work);
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_has_data(bio) && bio_end_sector(bio) > mddev->array_sectors))
  return DM_MAPIO_REQUEUE;

if (unlikely(!md_handle_request(mddev, bio)))
  return DM_MAPIO_REQUEUE;

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,
    enum sync_state state, sector_t resync_max_sectors)
{
sector_t r;
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 {
  if (state == st_idle && !test_bit(MD_RECOVERY_INTR, &recovery))
   r = mddev->resync_offset;
  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.
*
* Already retrieved recovery offset from curr_resync_completed above.
*/
   ;

  else if (state == st_resync || state == st_reshape)
   /*
* If "resync/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 if (test_bit(MD_RECOVERY_NEEDED, &recovery))
   /*
* We are idle and recovery is needed, prevent 'A' chars race
* caused by components still set to in-sync by constructor.
*/
   set_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);

  else {
   /*
* We are idle and 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.
*/
   struct md_rdev *rdev;

   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 = rs_is_raid456(rs) ? mddev->private : NULL;
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_writemostly_count = 0;
sector_t progress, resync_max_sectors, resync_mismatches;
enum sync_state state;
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();
  /* 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;
  recovery = rs->md.recovery;
  state = decipher_sync_action(mddev, recovery);
  progress = rs_get_progress(rs, recovery, state, resync_max_sectors);
  resync_mismatches = mddev->last_sync_action == ACTION_CHECK ?
        atomic64_read(&mddev->resync_mismatches) : 0;

  /* 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/admin-guide/device-mapper/dm-raid.rst for
*   information on each of these states.
*/
  DMEMIT(" %s", sync_str(state));

  /*
* 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 */

  /*
* Count any rebuild or writemostly argument pairs and subtract the
* hweight count being added below of any rebuild and writemostly ctr flags.
*/
  for (i = 0; i < rs->raid_disks; i++) {
   rebuild_writemostly_count += (test_bit(i, (void *) rs->rebuild_disks) ? 2 : 0) +
           (test_bit(WriteMostly, &rs->dev[i].rdev.flags) ? 2 : 0);
  }
  rebuild_writemostly_count -= (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags) ? 2 : 0) +
          (test_bit(__CTR_FLAG_WRITE_MOSTLY, &rs->ctr_flags) ? 2 : 0);
  /* Calculate raid parameter count based on ^ rebuild/writemostly argument counts and ctr flags set. */
  raid_param_cnt += rebuild_writemostly_count +
      hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_NO_ARGS) +
      hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_ONE_ARG) * 2;
  /* 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 (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags))
   for (i = 0; i < rs->raid_disks; i++)
    if (test_bit(i, (void *) rs->rebuild_disks))
     DMEMIT(" %s %u", dm_raid_arg_name_by_flag(CTR_FLAG_REBUILD), i);
  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 (test_bit(__CTR_FLAG_WRITE_MOSTLY, &rs->ctr_flags))
   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));
  break;

case STATUSTYPE_IMA:
  rt = get_raid_type_by_ll(mddev->new_level, mddev->new_layout);
  if (!rt)
   return;

  DMEMIT_TARGET_NAME_VERSION(ti->type);
  DMEMIT(",raid_type=%s,raid_disks=%d", rt->name, mddev->raid_disks);

  /* Access most recent mddev properties for status output */
  smp_rmb();
  recovery = rs->md.recovery;
  state = decipher_sync_action(mddev, recovery);
  DMEMIT(",raid_state=%s", sync_str(state));

  for (i = 0; i < rs->raid_disks; i++) {
   DMEMIT(",raid_device_%d_status=", i);
   DMEMIT(__raid_dev_status(rs, &rs->dev[i].rdev));
  }

  if (rt_is_raid456(rt)) {
   DMEMIT(",journal_dev_mode=");
   switch (rs->journal_dev.mode) {
   case R5C_JOURNAL_MODE_WRITE_THROUGH:
    DMEMIT("%s",
           _raid456_journal_mode[R5C_JOURNAL_MODE_WRITE_THROUGH].param);
    break;
   case R5C_JOURNAL_MODE_WRITE_BACK:
    DMEMIT("%s",
           _raid456_journal_mode[R5C_JOURNAL_MODE_WRITE_BACK].param);
    break;
   default:
    DMEMIT("invalid");
    break;
   }
  }
  DMEMIT(";");
  break;
}
}

static int raid_message(struct dm_target *ti, unsigned int argc, char **argv,
   char *result, unsigned int maxlen)
{
struct raid_set *rs = ti->private;
struct mddev *mddev = &rs->md;
int ret = 0;

if (!mddev->pers || !mddev->pers->sync_request)
  return -EINVAL;

if (test_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags) ||
     test_bit(RT_FLAG_RS_FROZEN, &rs->runtime_flags))
  return -EBUSY;

if (!strcasecmp(argv[0], "frozen")) {
  ret = mddev_lock(mddev);
  if (ret)
   return ret;

  md_frozen_sync_thread(mddev);
  mddev_unlock(mddev);
} else if (!strcasecmp(argv[0], "idle")) {
  ret = mddev_lock(mddev);
  if (ret)
   return ret;

  md_idle_sync_thread(mddev);
  mddev_unlock(mddev);
}

clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
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)
   md_wakeup_thread(mddev->sync_thread);
}
set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
if (!mddev->suspended)
  md_wakeup_thread(mddev->thread);

return 0;
}

static int raid_iterate_devices(struct dm_target *ti,
    iterate_devices_callout_fn fn, void *data)
{
struct raid_set *rs = ti->private;
unsigned int i;
int r = 0;

for (i = 0; !r && i < rs->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_bytes = to_bytes(rs->md.chunk_sectors);

if (chunk_size_bytes) {
  limits->io_min = chunk_size_bytes;
  limits->io_opt = chunk_size_bytes * mddev_data_stripes(rs);
}
}

static void raid_presuspend(struct dm_target *ti)
{
struct raid_set *rs = ti->private;
struct mddev *mddev = &rs->md;

/*
* From now on, disallow raid_message() to change sync_thread until
* resume, raid_postsuspend() is too late.
*/
set_bit(RT_FLAG_RS_FROZEN, &rs->runtime_flags);

if (!reshape_interrupted(mddev))
  return;

/*
* For raid456, if reshape is interrupted, IO across reshape position
* will never make progress, while caller will wait for IO to be done.
* Inform raid456 to handle those IO to prevent deadlock.
*/
if (mddev->pers && mddev->pers->prepare_suspend)
  mddev->pers->prepare_suspend(mddev);
}

static void raid_presuspend_undo(struct dm_target *ti)
{
struct raid_set *rs = ti->private;

clear_bit(RT_FLAG_RS_FROZEN, &rs->runtime_flags);
}

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)) {
  /*
* sync_thread must be stopped during suspend, and writes have
* to be stopped before suspending to avoid deadlocks.
*/
  md_stop_writes(&rs->md);
  mddev_suspend(&rs->md, false);
}
}

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 < rs->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)) {
  struct mddev *mddev = &rs->md;

  r = mddev->bitmap_ops->load(mddev);
  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;

/* If different and no explicit grow request, expose MD array size as of superblock. */
if (!test_bit(RT_FLAG_RS_GROW, &rs->runtime_flags) &&
     rs->array_sectors != mddev->array_sectors)
  rs_set_capacity(rs);

/*
* 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;

/* We are extending the raid set size, adjust mddev/md_rdev sizes and set capacity. */
if (test_bit(RT_FLAG_RS_GROW, &rs->runtime_flags)) {
  mddev->array_sectors = rs->array_sectors;
  mddev->dev_sectors = rs->dev_sectors;
  rs_set_rdev_sectors(rs);
  rs_set_capacity(rs);
}

/* Resize bitmap to adjust to changed region size (aka MD bitmap chunksize) or grown device size */
if (test_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags) && mddev->bitmap &&
     (test_bit(RT_FLAG_RS_GROW, &rs->runtime_flags) ||
      (rs->requested_bitmap_chunk_sectors &&
        mddev->bitmap_info.chunksize != to_bytes(rs->requested_bitmap_chunk_sectors)))) {
  int chunksize = to_bytes(rs->requested_bitmap_chunk_sectors) ?: mddev->bitmap_info.chunksize;

  r = mddev->bitmap_ops->resize(mddev, mddev->dev_sectors,
           chunksize, false);
  if (r)
   DMERR("Failed to resize bitmap");
}

/* Check for any resize/reshape on @rs and adjust/initiate */
if (mddev->resync_offset && mddev->resync_offset < MaxSector) {
  set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
  mddev->resync_min = mddev->resync_offset;
  if (test_bit(RT_FLAG_RS_GROW, &rs->runtime_flags))
   mddev->resync_max_sectors = mddev->dev_sectors;
}

/* 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.
*/
  mddev_lock_nointr(mddev);
  attempt_restore_of_faulty_devices(rs);
  mddev_unlock(mddev);
}

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);
  WARN_ON_ONCE(!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery));
  WARN_ON_ONCE(rcu_dereference_protected(mddev->sync_thread,
             lockdep_is_held(&mddev->reconfig_mutex)));
  clear_bit(RT_FLAG_RS_FROZEN, &rs->runtime_flags);
  mddev->ro = 0;
  mddev->in_sync = 0;
  md_unfrozen_sync_thread(mddev);
  mddev_unlock_and_resume(mddev);
}
}

static struct target_type raid_target = {
.name = "raid",
.version = {1, 15, 1},
.module = THIS_MODULE,
.ctr = raid_ctr,
.dtr = raid_dtr,
.map = raid_map,
.status = raid_status,
.message = raid_message,
.iterate_devices = raid_iterate_devices,
.io_hints = raid_io_hints,
.presuspend = raid_presuspend,
.presuspend_undo = raid_presuspend_undo,
.postsuspend = raid_postsuspend,
.preresume = raid_preresume,
.resume = raid_resume,
};
module_dm(raid);

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@lists.linux.dev>");
MODULE_AUTHOR("Heinz Mauelshagen <dm-devel@lists.linux.dev>");
MODULE_LICENSE("GPL");

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