net: s2io: simplify logical constraint
[deliverable/linux.git] / drivers / md / dm-raid.c
index 52532745a50f85d6eb765d8d6fcaa838301334b6..84983549b5e10e70c98ae8aadce7adb1eef2692e 100644 (file)
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2010-2011 Neil Brown
- * Copyright (C) 2010-2015 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2010-2016 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the GPL.
  */
 #include <linux/device-mapper.h>
 
 #define DM_MSG_PREFIX "raid"
-#define        MAX_RAID_DEVICES        253 /* raid4/5/6 limit */
+#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)
 
 static bool devices_handle_discard_safely = false;
 
@@ -25,12 +30,12 @@ static bool devices_handle_discard_safely = false;
  * The following flags are used by dm-raid.c to set up the array state.
  * They must be cleared before md_run is called.
  */
-#define FirstUse 10             /* rdev flag */
+#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
+        * actual data/parity.  The reason for this is to not confuse
         * ti->len and give more flexibility in altering size and
         * characteristics.
         *
@@ -45,26 +50,176 @@ struct raid_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! */
+
 /*
  * Flags for rs->ctr_flags field.
  */
-#define CTR_FLAG_SYNC              0x1
-#define CTR_FLAG_NOSYNC            0x2
-#define CTR_FLAG_REBUILD           0x4
-#define CTR_FLAG_DAEMON_SLEEP      0x8
-#define CTR_FLAG_MIN_RECOVERY_RATE 0x10
-#define CTR_FLAG_MAX_RECOVERY_RATE 0x20
-#define CTR_FLAG_MAX_WRITE_BEHIND  0x40
-#define CTR_FLAG_STRIPE_CACHE      0x80
-#define CTR_FLAG_REGION_SIZE       0x100
-#define CTR_FLAG_RAID10_COPIES     0x200
-#define CTR_FLAG_RAID10_FORMAT     0x400
+#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)
+
+/*
+ * Definitions of various constructor flags to
+ * be used in checks of valid / invalid flags
+ * per raid level.
+ */
+/* Define all any sync flags */
+#define        CTR_FLAGS_ANY_SYNC              (CTR_FLAG_SYNC | CTR_FLAG_NOSYNC)
+
+/* Define flags for options without argument (e.g. 'nosync') */
+#define        CTR_FLAG_OPTIONS_NO_ARGS        (CTR_FLAGS_ANY_SYNC | \
+                                        CTR_FLAG_RAID10_USE_NEAR_SETS)
+
+/* Define flags for options with one argument (e.g. 'delta_disks +2') */
+#define CTR_FLAG_OPTIONS_ONE_ARG (CTR_FLAG_REBUILD | \
+                                 CTR_FLAG_WRITE_MOSTLY | \
+                                 CTR_FLAG_DAEMON_SLEEP | \
+                                 CTR_FLAG_MIN_RECOVERY_RATE | \
+                                 CTR_FLAG_MAX_RECOVERY_RATE | \
+                                 CTR_FLAG_MAX_WRITE_BEHIND | \
+                                 CTR_FLAG_STRIPE_CACHE | \
+                                 CTR_FLAG_REGION_SIZE | \
+                                 CTR_FLAG_RAID10_COPIES | \
+                                 CTR_FLAG_RAID10_FORMAT | \
+                                 CTR_FLAG_DELTA_DISKS | \
+                                 CTR_FLAG_DATA_OFFSET)
+
+/* Valid options definitions per raid level... */
+
+/* "raid0" does only accept data offset */
+#define RAID0_VALID_FLAGS      (CTR_FLAG_DATA_OFFSET)
+
+/* "raid1" does not accept stripe cache, data offset, delta_disks or any raid10 options */
+#define RAID1_VALID_FLAGS      (CTR_FLAGS_ANY_SYNC | \
+                                CTR_FLAG_REBUILD | \
+                                CTR_FLAG_WRITE_MOSTLY | \
+                                CTR_FLAG_DAEMON_SLEEP | \
+                                CTR_FLAG_MIN_RECOVERY_RATE | \
+                                CTR_FLAG_MAX_RECOVERY_RATE | \
+                                CTR_FLAG_MAX_WRITE_BEHIND | \
+                                CTR_FLAG_REGION_SIZE | \
+                                CTR_FLAG_DELTA_DISKS | \
+                                CTR_FLAG_DATA_OFFSET)
+
+/* "raid10" does not accept any raid1 or stripe cache options */
+#define RAID10_VALID_FLAGS     (CTR_FLAGS_ANY_SYNC | \
+                                CTR_FLAG_REBUILD | \
+                                CTR_FLAG_DAEMON_SLEEP | \
+                                CTR_FLAG_MIN_RECOVERY_RATE | \
+                                CTR_FLAG_MAX_RECOVERY_RATE | \
+                                CTR_FLAG_REGION_SIZE | \
+                                CTR_FLAG_RAID10_COPIES | \
+                                CTR_FLAG_RAID10_FORMAT | \
+                                CTR_FLAG_DELTA_DISKS | \
+                                CTR_FLAG_DATA_OFFSET | \
+                                CTR_FLAG_RAID10_USE_NEAR_SETS)
+
+/*
+ * "raid4/5/6" do not accept any raid1 or raid10 specific options
+ *
+ * "raid6" does not accept "nosync", because it is not guaranteed
+ * that both parity and q-syndrome are being written properly with
+ * any writes
+ */
+#define RAID45_VALID_FLAGS     (CTR_FLAGS_ANY_SYNC | \
+                                CTR_FLAG_REBUILD | \
+                                CTR_FLAG_DAEMON_SLEEP | \
+                                CTR_FLAG_MIN_RECOVERY_RATE | \
+                                CTR_FLAG_MAX_RECOVERY_RATE | \
+                                CTR_FLAG_MAX_WRITE_BEHIND | \
+                                CTR_FLAG_STRIPE_CACHE | \
+                                CTR_FLAG_REGION_SIZE | \
+                                CTR_FLAG_DELTA_DISKS | \
+                                CTR_FLAG_DATA_OFFSET)
+
+#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_MAX_WRITE_BEHIND | \
+                                CTR_FLAG_STRIPE_CACHE | \
+                                CTR_FLAG_REGION_SIZE | \
+                                CTR_FLAG_DELTA_DISKS | \
+                                CTR_FLAG_DATA_OFFSET)
+/* ...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_KEEP_RS_FROZEN         5
+
+/* 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 bitmap_loaded;
-       uint32_t ctr_flags;
+       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;
@@ -73,82 +228,446 @@ struct raid_set {
        struct raid_dev dev[0];
 };
 
+static void rs_config_backup(struct raid_set *rs, struct rs_layout *l)
+{
+       struct mddev *mddev = &rs->md;
+
+       l->new_level = mddev->new_level;
+       l->new_layout = mddev->new_layout;
+       l->new_chunk_sectors = mddev->new_chunk_sectors;
+}
+
+static void rs_config_restore(struct raid_set *rs, struct rs_layout *l)
+{
+       struct mddev *mddev = &rs->md;
+
+       mddev->new_level = l->new_level;
+       mddev->new_layout = l->new_layout;
+       mddev->new_chunk_sectors = l->new_chunk_sectors;
+}
+
+/* raid10 algorithms (i.e. formats) */
+#define        ALGORITHM_RAID10_DEFAULT        0
+#define        ALGORITHM_RAID10_NEAR           1
+#define        ALGORITHM_RAID10_OFFSET         2
+#define        ALGORITHM_RAID10_FAR            3
+
 /* Supported raid types and properties. */
 static struct raid_type {
        const char *name;               /* RAID algorithm. */
        const char *descr;              /* Descriptor text for logging. */
-       const unsigned parity_devs;     /* # of parity devices. */
-       const unsigned minimal_devs;    /* minimal # of devices in set. */
-       const unsigned level;           /* RAID level. */
-       const unsigned algorithm;       /* RAID algorithm. */
+       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",   "RAID10 (striped mirrors)",        0, 2, 10, UINT_MAX /* Varies */},
-       {"raid4",    "RAID4 (dedicated parity disk)",   1, 2, 5, ALGORITHM_PARITY_0},
-       {"raid5_la", "RAID5 (left asymmetric)",         1, 2, 5, ALGORITHM_LEFT_ASYMMETRIC},
-       {"raid5_ra", "RAID5 (right asymmetric)",        1, 2, 5, ALGORITHM_RIGHT_ASYMMETRIC},
-       {"raid5_ls", "RAID5 (left symmetric)",          1, 2, 5, ALGORITHM_LEFT_SYMMETRIC},
-       {"raid5_rs", "RAID5 (right symmetric)",         1, 2, 5, ALGORITHM_RIGHT_SYMMETRIC},
-       {"raid6_zr", "RAID6 (zero restart)",            2, 4, 6, ALGORITHM_ROTATING_ZERO_RESTART},
-       {"raid6_nr", "RAID6 (N restart)",               2, 4, 6, ALGORITHM_ROTATING_N_RESTART},
-       {"raid6_nc", "RAID6 (N continue)",              2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE}
+       {"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 last parity disk)",     1, 2, 4,  ALGORITHM_PARITY_N}, /* raid4 layout = raid5_n */
+       {"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"},
 };
 
-static char *raid10_md_layout_to_format(int layout)
+/* 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;
+}
+
+/*
+ * Bool helpers to test for various raid levels of a raid set.
+ * It's level as reported by the superblock rather than
+ * the requested raid_type passed to the constructor.
+ */
+/* Return true, if raid set in @rs is raid0 */
+static bool rs_is_raid0(struct raid_set *rs)
+{
+       return !rs->md.level;
+}
+
+/* Return true, if raid set in @rs is raid1 */
+static bool rs_is_raid1(struct raid_set *rs)
+{
+       return rs->md.level == 1;
+}
+
+/* Return true, if raid set in @rs is raid10 */
+static bool rs_is_raid10(struct raid_set *rs)
+{
+       return rs->md.level == 10;
+}
+
+/* Return true, if raid set in @rs is level 6 */
+static bool rs_is_raid6(struct raid_set *rs)
+{
+       return rs->md.level == 6;
+}
+
+/* Return true, if raid set in @rs is level 4, 5 or 6 */
+static bool rs_is_raid456(struct raid_set *rs)
+{
+       return __within_range(rs->md.level, 4, 6);
+}
+
+/* Return true, if raid set in @rs is reshapable */
+static bool __is_raid10_far(int layout);
+static bool rs_is_reshapable(struct raid_set *rs)
+{
+       return rs_is_raid456(rs) ||
+              (rs_is_raid10(rs) && !__is_raid10_far(rs->md.new_layout));
+}
+
+/* Return true, if raid set in @rs is recovering */
+static bool rs_is_recovering(struct raid_set *rs)
+{
+       return rs->md.recovery_cp < rs->dev[0].rdev.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 and 17 stand for "offset" and "use_far_sets"
+        * Bit 16 stands for "offset"
+        * (i.e. adjacent stripes hold copies)
+        *
         * Refer to MD's raid10.c for details
         */
-       if ((layout & 0x10000) && (layout & 0x20000))
+       if (__is_raid10_offset(layout))
                return "offset";
 
-       if ((layout & 0xFF) > 1)
+       if (__raid10_near_copies(layout) > 1)
                return "near";
 
+       WARN_ON(__raid10_far_copies(layout) < 2);
+
        return "far";
 }
 
-static unsigned raid10_md_layout_to_copies(int layout)
+/* Return md raid10 algorithm for @name */
+static int raid10_name_to_format(const char *name)
 {
-       if ((layout & 0xFF) > 1)
-               return layout & 0xFF;
-       return (layout >> 8) & 0xFF;
+       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));
 }
 
-static int raid10_format_to_md_layout(char *format, unsigned copies)
+/* 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 n = 1, f = 1;
+       unsigned int n = 1, f = 1, r = 0;
 
-       if (!strcasecmp("near", format))
+       /*
+        * 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
+
+       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;
 
-       if (!strcasecmp("offset", format))
-               return 0x30000 | (f << 8) | n;
+       } else if (algorithm == ALGORITHM_RAID10_FAR) {
+               f = copies;
+               r = !RAID10_OFFSET;
+               if (!test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags))
+                       r |= RAID10_USE_FAR_SETS;
 
-       if (!strcasecmp("far", format))
-               return 0x20000 | (f << 8) | n;
+       } else
+               return -EINVAL;
 
-       return (f << 8) | n;
+       return r | (f << RAID10_FAR_COPIES_SHIFT) | n;
 }
+/* END: MD raid10 bit definitions and helpers */
 
-static struct raid_type *get_raid_type(char *name)
+/* Check for any of the raid10 algorithms */
+static bool __got_raid10(struct raid_type *rtp, const int layout)
 {
-       int i;
+       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);
 
-       for (i = 0; i < ARRAY_SIZE(raid_types); i++)
-               if (!strcmp(raid_types[i].name, name))
-                       return &raid_types[i];
+       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;
 }
 
-static struct raid_set *context_alloc(struct dm_target *ti, struct raid_type *raid_type, unsigned raid_devs)
+/*
+ * Conditionally change bdev capacity of @rs
+ * in case of a disk add/remove reshape
+ */
+static void rs_set_capacity(struct raid_set *rs)
+{
+       struct mddev *mddev = &rs->md;
+       struct md_rdev *rdev;
+       struct gendisk *gendisk = dm_disk(dm_table_get_md(rs->ti->table));
+
+       /*
+        * raid10 sets rdev->sector to the device size, which
+        * is unintended in case of out-of-place reshaping
+        */
+       rdev_for_each(rdev, mddev)
+               rdev->sectors = mddev->dev_sectors;
+
+       set_capacity(gendisk, mddev->array_sectors);
+       revalidate_disk(gendisk);
+}
+
+/*
+ * Set the mddev properties in @rs to the current
+ * ones retrieved from the freshest superblock
+ */
+static void rs_set_cur(struct raid_set *rs)
+{
+       struct mddev *mddev = &rs->md;
+
+       mddev->new_level = mddev->level;
+       mddev->new_layout = mddev->layout;
+       mddev->new_chunk_sectors = mddev->chunk_sectors;
+}
+
+/*
+ * Set the mddev properties in @rs to the new
+ * ones requested by the ctr
+ */
+static void rs_set_new(struct raid_set *rs)
+{
+       struct mddev *mddev = &rs->md;
+
+       mddev->level = mddev->new_level;
+       mddev->layout = mddev->new_layout;
+       mddev->chunk_sectors = mddev->new_chunk_sectors;
+       mddev->raid_disks = rs->raid_disks;
+       mddev->delta_disks = 0;
+}
+
+static struct raid_set *raid_set_alloc(struct dm_target *ti, struct raid_type *raid_type,
+                                      unsigned int raid_devs)
 {
-       unsigned i;
+       unsigned int i;
        struct raid_set *rs;
 
        if (raid_devs <= raid_type->parity_devs) {
@@ -164,15 +683,19 @@ static struct raid_set *context_alloc(struct dm_target *ti, struct raid_type *ra
 
        mddev_init(&rs->md);
 
+       rs->raid_disks = raid_devs;
+       rs->delta_disks = 0;
+
        rs->ti = ti;
        rs->raid_type = raid_type;
+       rs->stripe_cache_entries = 256;
        rs->md.raid_disks = raid_devs;
        rs->md.level = raid_type->level;
        rs->md.new_level = rs->md.level;
        rs->md.layout = raid_type->algorithm;
        rs->md.new_layout = rs->md.layout;
        rs->md.delta_disks = 0;
-       rs->md.recovery_cp = 0;
+       rs->md.recovery_cp = MaxSector;
 
        for (i = 0; i < raid_devs; i++)
                md_rdev_init(&rs->dev[i].rdev);
@@ -189,11 +712,11 @@ static struct raid_set *context_alloc(struct dm_target *ti, struct raid_type *ra
        return rs;
 }
 
-static void context_free(struct raid_set *rs)
+static void raid_set_free(struct raid_set *rs)
 {
        int i;
 
-       for (i = 0; i < rs->md.raid_disks; i++) {
+       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);
@@ -218,16 +741,22 @@ static void context_free(struct raid_set *rs)
  *    <meta_dev> -
  *
  * This code parses those words.  If there is a failure,
- * the caller must use context_free to unwind the operations.
+ * the caller must use raid_set_free() to unwind the operations.
  */
-static int dev_parms(struct raid_set *rs, char **argv)
+static int parse_dev_params(struct raid_set *rs, struct dm_arg_set *as)
 {
        int i;
        int rebuild = 0;
        int metadata_available = 0;
-       int ret = 0;
+       int r = 0;
+       const char *arg;
 
-       for (i = 0; i < rs->md.raid_disks; i++, argv += 2) {
+       /* 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;
@@ -240,39 +769,49 @@ static int dev_parms(struct raid_set *rs, char **argv)
                rs->dev[i].rdev.data_offset = 0;
                rs->dev[i].rdev.mddev = &rs->md;
 
-               if (strcmp(argv[0], "-")) {
-                       ret = dm_get_device(rs->ti, argv[0],
-                                           dm_table_get_mode(rs->ti->table),
-                                           &rs->dev[i].meta_dev);
-                       rs->ti->error = "RAID metadata device lookup failure";
-                       if (ret)
-                               return ret;
+               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)
+                       if (!rs->dev[i].rdev.sb_page) {
+                               rs->ti->error = "Failed to allocate superblock page";
                                return -ENOMEM;
+                       }
                }
 
-               if (!strcmp(argv[1], "-")) {
+               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;
                        }
 
-                       rs->ti->error = "No data device supplied with metadata device";
-                       if (rs->dev[i].meta_dev)
+                       if (rs->dev[i].meta_dev) {
+                               rs->ti->error = "No data device supplied with metadata device";
                                return -EINVAL;
+                       }
 
                        continue;
                }
 
-               ret = dm_get_device(rs->ti, argv[1],
-                                   dm_table_get_mode(rs->ti->table),
-                                   &rs->dev[i].data_dev);
-               if (ret) {
+               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 ret;
+                       return r;
                }
 
                if (rs->dev[i].meta_dev) {
@@ -280,7 +819,7 @@ static int dev_parms(struct raid_set *rs, char **argv)
                        rs->dev[i].rdev.meta_bdev = rs->dev[i].meta_dev->bdev;
                }
                rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev;
-               list_add(&rs->dev[i].rdev.same_set, &rs->md.disks);
+               list_add_tail(&rs->dev[i].rdev.same_set, &rs->md.disks);
                if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
                        rebuild++;
        }
@@ -301,8 +840,7 @@ static int dev_parms(struct raid_set *rs, char **argv)
                 *
                 * User could specify 'nosync' option if desperate.
                 */
-               DMERR("Unable to rebuild drive while array is not in-sync");
-               rs->ti->error = "RAID device lookup failure";
+               rs->ti->error = "Unable to rebuild drive while array is not in-sync";
                return -EINVAL;
        }
 
@@ -325,7 +863,7 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
 
        if (!region_size) {
                /*
-                * Choose a reasonable default.  All figures in sectors.
+                * 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 */
@@ -366,7 +904,7 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
        /*
         * Convert sectors to bytes.
         */
-       rs->md.bitmap_info.chunksize = (region_size << 9);
+       rs->md.bitmap_info.chunksize = to_bytes(region_size);
 
        return 0;
 }
@@ -382,9 +920,9 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
  */
 static int validate_raid_redundancy(struct raid_set *rs)
 {
-       unsigned i, rebuild_cnt = 0;
-       unsigned rebuilds_per_group = 0, copies, d;
-       unsigned group_size, last_group_start;
+       unsigned int i, rebuild_cnt = 0;
+       unsigned int rebuilds_per_group = 0, copies;
+       unsigned int group_size, last_group_start;
 
        for (i = 0; i < rs->md.raid_disks; i++)
                if (!test_bit(In_sync, &rs->dev[i].rdev.flags) ||
@@ -403,7 +941,7 @@ static int validate_raid_redundancy(struct raid_set *rs)
                        goto too_many;
                break;
        case 10:
-               copies = raid10_md_layout_to_copies(rs->md.layout);
+               copies = raid10_md_layout_to_copies(rs->md.new_layout);
                if (rebuild_cnt < copies)
                        break;
 
@@ -417,17 +955,16 @@ static int validate_raid_redundancy(struct raid_set *rs)
                 * 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
+                * E.g.    dev1 dev2 dev3 dev4 dev5
+                *          A    A    B    B    C
+                *          C    D    D    E    E
                 */
-               if (!strcmp("near", raid10_md_layout_to_format(rs->md.layout))) {
-                       for (i = 0; i < rs->md.raid_disks * copies; i++) {
+               if (__is_raid10_near(rs->md.new_layout)) {
+                       for (i = 0; i < rs->md.raid_disks; i++) {
                                if (!(i % copies))
                                        rebuilds_per_group = 0;
-                               d = i % rs->md.raid_disks;
-                               if ((!rs->dev[d].rdev.sb_page ||
-                                    !test_bit(In_sync, &rs->dev[d].rdev.flags)) &&
+                               if ((!rs->dev[i].rdev.sb_page ||
+                                   !test_bit(In_sync, &rs->dev[i].rdev.flags)) &&
                                    (++rebuilds_per_group >= copies))
                                        goto too_many;
                        }
@@ -442,7 +979,7 @@ static int validate_raid_redundancy(struct raid_set *rs)
                 * 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
+                * for arrays that are not a multiple of (far) copies.  This
                 * results in the need to treat the last (potentially larger)
                 * set differently.
                 */
@@ -475,42 +1012,48 @@ too_many:
  *
  * Argument definitions
  *    <chunk_size>                     The number of sectors per disk that
- *                                      will form the "stripe"
+ *                                     will form the "stripe"
  *    [[no]sync]                       Force or prevent recovery of the
- *                                      entire array
+ *                                     entire array
  *    [rebuild <idx>]                  Rebuild the drive indicated by the index
  *    [daemon_sleep <ms>]              Time between bitmap daemon work to
- *                                      clear bits
+ *                                     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
+ *    [region_size <sectors>]          Defines granularity of bitmap
  *
  * RAID10-only options:
- *    [raid10_copies <# copies>]        Number of copies.  (Default: 2)
+ *    [raid10_copies <# copies>]       Number of copies.  (Default: 2)
  *    [raid10_format <near|far|offset>] Layout algorithm.  (Default: near)
  */
-static int parse_raid_params(struct raid_set *rs, char **argv,
-                            unsigned num_raid_params)
-{
-       char *raid10_format = "near";
-       unsigned raid10_copies = 2;
-       unsigned i;
-       unsigned long value, region_size = 0;
-       sector_t sectors_per_dev = rs->ti->len;
+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;
-       char *key;
+       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 ((kstrtoul(argv[0], 10, &value) < 0)) {
-               rs->ti->error = "Bad chunk size";
-               return -EINVAL;
-       } else if (rs->raid_type->level == 1) {
+       if (rt_is_raid1(rt)) {
                if (value)
                        DMERR("Ignoring chunk size parameter for RAID 1");
                value = 0;
@@ -523,8 +1066,6 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
        }
 
        rs->md.new_chunk_sectors = rs->md.chunk_sectors = value;
-       argv++;
-       num_raid_params--;
 
        /*
         * We set each individual device as In_sync with a completed
@@ -532,18 +1073,18 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
         * replacement then one of the following cases applies:
         *
         *   1) User specifies 'rebuild'.
-        *      - Device is reset when param is read.
+        *      - Device is reset when param is read.
         *   2) A new device is supplied.
-        *      - No matching superblock found, resets device.
+        *      - No matching superblock found, resets device.
         *   3) Device failure was transient and returns on reload.
-        *      - Failure noticed, resets device for bitmap replay.
+        *      - Failure noticed, resets device for bitmap replay.
         *   4) Device hadn't completed recovery after previous failure.
-        *      - Superblock is read and overrides recovery_offset.
+        *      - Superblock is read and overrides recovery_offset.
         *
         * What is found in the superblocks of the devices is always
         * authoritative, unless 'rebuild' or '[no]sync' was specified.
         */
-       for (i = 0; i < rs->md.raid_disks; i++) {
+       for (i = 0; i < rs->raid_disks; i++) {
                set_bit(In_sync, &rs->dev[i].rdev.flags);
                rs->dev[i].rdev.recovery_offset = MaxSector;
        }
@@ -552,72 +1093,112 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
         * Second, parse the unordered optional arguments
         */
        for (i = 0; i < num_raid_params; i++) {
-               if (!strcasecmp(argv[i], "nosync")) {
-                       rs->md.recovery_cp = MaxSector;
-                       rs->ctr_flags |= CTR_FLAG_NOSYNC;
+               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(argv[i], "sync")) {
-                       rs->md.recovery_cp = 0;
-                       rs->ctr_flags |= CTR_FLAG_SYNC;
+               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;
                }
 
-               /* The rest of the optional arguments come in key/value pairs */
-               if ((i + 1) >= num_raid_params) {
+               arg = dm_shift_arg(as);
+               i++; /* Account for the argument pairs */
+               if (!arg) {
                        rs->ti->error = "Wrong number of raid parameters given";
                        return -EINVAL;
                }
 
-               key = argv[i++];
+               /*
+                * Parameters that take a string value are checked here.
+                */
 
-               /* Parameters that take a string value are checked here. */
-               if (!strcasecmp(key, "raid10_format")) {
-                       if (rs->raid_type->level != 10) {
+               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;
                        }
-                       if (strcmp("near", argv[i]) &&
-                           strcmp("far", argv[i]) &&
-                           strcmp("offset", argv[i])) {
+                       raid10_format = raid10_name_to_format(arg);
+                       if (raid10_format < 0) {
                                rs->ti->error = "Invalid 'raid10_format' value given";
-                               return -EINVAL;
+                               return raid10_format;
                        }
-                       raid10_format = argv[i];
-                       rs->ctr_flags |= CTR_FLAG_RAID10_FORMAT;
                        continue;
                }
 
-               if (kstrtoul(argv[i], 10, &value) < 0) {
+               if (kstrtoint(arg, 10, &value) < 0) {
                        rs->ti->error = "Bad numerical argument given in raid params";
                        return -EINVAL;
                }
 
-               /* Parameters that take a numeric value are checked here */
-               if (!strcasecmp(key, "rebuild")) {
-                       if (value >= rs->md.raid_disks) {
+               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;
                        }
-                       clear_bit(In_sync, &rs->dev[value].rdev.flags);
-                       rs->dev[value].rdev.recovery_offset = 0;
-                       rs->ctr_flags |= CTR_FLAG_REBUILD;
-               } else if (!strcasecmp(key, "write_mostly")) {
-                       if (rs->raid_type->level != 1) {
+
+                       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 (value >= rs->md.raid_disks) {
-                               rs->ti->error = "Invalid write_mostly drive index given";
+
+                       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);
-               } else if (!strcasecmp(key, "max_write_behind")) {
-                       if (rs->raid_type->level != 1) {
+                       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;
                        }
-                       rs->ctr_flags |= CTR_FLAG_MAX_WRITE_BEHIND;
+
+                       if (test_and_set_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags)) {
+                               rs->ti->error = "Only one max_write_behind argument pair allowed";
+                               return -EINVAL;
+                       }
 
                        /*
                         * In device-mapper, we specify things in sectors, but
@@ -628,65 +1209,122 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
                                rs->ti->error = "Max write-behind limit out of range";
                                return -EINVAL;
                        }
+
                        rs->md.bitmap_info.max_write_behind = value;
-               } else if (!strcasecmp(key, "daemon_sleep")) {
-                       rs->ctr_flags |= CTR_FLAG_DAEMON_SLEEP;
+               } 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 || (value > MAX_SCHEDULE_TIMEOUT)) {
                                rs->ti->error = "daemon sleep period out of range";
                                return -EINVAL;
                        }
                        rs->md.bitmap_info.daemon_sleep = value;
-               } else if (!strcasecmp(key, "stripe_cache")) {
-                       rs->ctr_flags |= CTR_FLAG_STRIPE_CACHE;
+               } else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DATA_OFFSET))) {
+                       /* Userspace passes new data_offset after having extended the the data image LV */
+                       if (test_and_set_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
+                               rs->ti->error = "Only one data_offset argument pair allowed";
+                               return -EINVAL;
+                       }
+                       /* Ensure sensible data offset */
+                       if (value < 0 ||
+                           (value && (value < MIN_FREE_RESHAPE_SPACE || value % to_sector(PAGE_SIZE)))) {
+                               rs->ti->error = "Bogus data_offset value";
+                               return -EINVAL;
+                       }
+                       rs->data_offset = value;
+               } else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DELTA_DISKS))) {
+                       /* Define the +/-# of disks to add to/remove from the given raid set */
+                       if (test_and_set_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags)) {
+                               rs->ti->error = "Only one delta_disks argument pair allowed";
+                               return -EINVAL;
+                       }
+                       /* Ensure MAX_RAID_DEVICES and raid type minimal_devs! */
+                       if (!__within_range(abs(value), 1, MAX_RAID_DEVICES - rt->minimal_devs)) {
+                               rs->ti->error = "Too many delta_disk requested";
+                               return -EINVAL;
+                       }
 
-                       /*
-                        * In device-mapper, we specify things in sectors, but
-                        * MD records this value in kB
-                        */
-                       value /= 2;
+                       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 ((rs->raid_type->level != 5) &&
-                           (rs->raid_type->level != 6)) {
+                       if (!rt_is_raid456(rt)) {
                                rs->ti->error = "Inappropriate argument: stripe_cache";
                                return -EINVAL;
                        }
-                       if (raid5_set_cache_size(&rs->md, (int)value)) {
-                               rs->ti->error = "Bad stripe_cache size";
+
+                       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;
                        }
-               } else if (!strcasecmp(key, "min_recovery_rate")) {
-                       rs->ctr_flags |= CTR_FLAG_MIN_RECOVERY_RATE;
                        if (value > INT_MAX) {
                                rs->ti->error = "min_recovery_rate out of range";
                                return -EINVAL;
                        }
                        rs->md.sync_speed_min = (int)value;
-               } else if (!strcasecmp(key, "max_recovery_rate")) {
-                       rs->ctr_flags |= CTR_FLAG_MAX_RECOVERY_RATE;
+               } else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MAX_RECOVERY_RATE))) {
+                       if (test_and_set_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags)) {
+                               rs->ti->error = "Only one max_recovery_rate argument pair allowed";
+                               return -EINVAL;
+                       }
                        if (value > INT_MAX) {
                                rs->ti->error = "max_recovery_rate out of range";
                                return -EINVAL;
                        }
                        rs->md.sync_speed_max = (int)value;
-               } else if (!strcasecmp(key, "region_size")) {
-                       rs->ctr_flags |= CTR_FLAG_REGION_SIZE;
+               } 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;
-               } else if (!strcasecmp(key, "raid10_copies") &&
-                          (rs->raid_type->level == 10)) {
-                       if ((value < 2) || (value > 0xFF)) {
+                       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;
                        }
-                       rs->ctr_flags |= CTR_FLAG_RAID10_COPIES;
+
                        raid10_copies = value;
                } else {
                        DMERR("Unable to parse RAID parameter: %s", key);
-                       rs->ti->error = "Unable to parse RAID parameters";
+                       rs->ti->error = "Unable to parse RAID parameter";
                        return -EINVAL;
                }
        }
 
-       if (validate_region_size(rs, region_size))
+       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 (validate_region_size(rs, region_size))
                return -EINVAL;
 
        if (rs->md.chunk_sectors)
@@ -697,47 +1335,193 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
        if (dm_set_target_max_io_len(rs->ti, max_io_len))
                return -EINVAL;
 
-       if (rs->raid_type->level == 10) {
+       if (rt_is_raid10(rt)) {
                if (raid10_copies > rs->md.raid_disks) {
                        rs->ti->error = "Not enough devices to satisfy specification";
                        return -EINVAL;
                }
 
-               /*
-                * If the format is not "near", we only support
-                * two copies at the moment.
-                */
-               if (strcmp("near", raid10_format) && (raid10_copies > 2)) {
-                       rs->ti->error = "Too many copies for given RAID10 format.";
+               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;
                }
 
-               /* (Len * #mirrors) / #devices */
-               sectors_per_dev = rs->ti->len * raid10_copies;
-               sector_div(sectors_per_dev, rs->md.raid_disks);
-
-               rs->md.layout = raid10_format_to_md_layout(raid10_format,
-                                                          raid10_copies);
-               rs->md.new_layout = rs->md.layout;
-       } else if ((!rs->raid_type->level || rs->raid_type->level > 1) &&
-                  sector_div(sectors_per_dev,
-                             (rs->md.raid_disks - rs->raid_type->parity_devs))) {
-               rs->ti->error = "Target length not divisible by number of data devices";
-               return -EINVAL;
+               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->md.dev_sectors = sectors_per_dev;
+
+       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;
+}
+
+/* Calculate the sectors per device and per array used for @rs */
+static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
+{
+       int delta_disks;
+       unsigned int data_stripes;
+       struct mddev *mddev = &rs->md;
+       struct md_rdev *rdev;
+       sector_t array_sectors = rs->ti->len, dev_sectors = rs->ti->len;
+
+       if (use_mddev) {
+               delta_disks = mddev->delta_disks;
+               data_stripes = mddev_data_stripes(rs);
+       } else {
+               delta_disks = rs->delta_disks;
+               data_stripes = rs_data_stripes(rs);
+       }
+
+       /* Special raid1 case w/o delta_disks support (yet) */
+       if (rt_is_raid1(rs->raid_type))
+               ;
+       else if (rt_is_raid10(rs->raid_type)) {
+               if (rs->raid10_copies < 2 ||
+                   delta_disks < 0) {
+                       rs->ti->error = "Bogus raid10 data copies or delta disks";
+                       return -EINVAL;
+               }
+
+               dev_sectors *= rs->raid10_copies;
+               if (sector_div(dev_sectors, data_stripes))
+                       goto bad;
+
+               array_sectors = (data_stripes + delta_disks) * dev_sectors;
+               if (sector_div(array_sectors, rs->raid10_copies))
+                       goto bad;
+
+       } else if (sector_div(dev_sectors, data_stripes))
+               goto bad;
+
+       else
+               /* Striped layouts */
+               array_sectors = (data_stripes + delta_disks) * dev_sectors;
+
+       rdev_for_each(rdev, mddev)
+               rdev->sectors = dev_sectors;
+
+       mddev->array_sectors = array_sectors;
+       mddev->dev_sectors = dev_sectors;
+
+       return 0;
+bad:
+       rs->ti->error = "Target length not divisible by number of data devices";
+       return -EINVAL;
+}
+
+/* Setup recovery on @rs */
+static void __rs_setup_recovery(struct raid_set *rs, sector_t dev_sectors)
+{
+       /* raid0 does not recover */
+       if (rs_is_raid0(rs))
+               rs->md.recovery_cp = MaxSector;
+       /*
+        * A raid6 set has to be recovered either
+        * completely or for the grown part to
+        * ensure proper parity and Q-Syndrome
+        */
+       else if (rs_is_raid6(rs))
+               rs->md.recovery_cp = dev_sectors;
+       /*
+        * Other raid set types may skip recovery
+        * depending on the 'nosync' flag.
+        */
+       else
+               rs->md.recovery_cp = test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)
+                                    ? MaxSector : dev_sectors;
+}
+
+/* Setup recovery on @rs based on raid type, device size and 'nosync' flag */
+static void rs_setup_recovery(struct raid_set *rs, sector_t dev_sectors)
+{
+       if (!dev_sectors)
+               /* New raid set or 'sync' flag provided */
+               __rs_setup_recovery(rs, 0);
+       else if (dev_sectors == MaxSector)
+               /* Prevent recovery */
+               __rs_setup_recovery(rs, MaxSector);
+       else if (rs->dev[0].rdev.sectors < dev_sectors)
+               /* Grown raid set */
+               __rs_setup_recovery(rs, rs->dev[0].rdev.sectors);
+       else
+               __rs_setup_recovery(rs, MaxSector);
+}
+
 static void do_table_event(struct work_struct *ws)
 {
        struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);
 
+       smp_rmb(); /* Make sure we access most actual mddev properties */
+       if (!rs_is_reshaping(rs))
+               rs_set_capacity(rs);
        dm_table_event(rs->ti->table);
 }
 
@@ -748,6 +1532,211 @@ static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
        return mddev_congested(&rs->md, bits);
 }
 
+/*
+ * Make sure a valid takover (level switch) is being requested on @rs
+ *
+ * Conversions of raid sets from one MD personality to another
+ * have to conform to restrictions which are enforced here.
+ */
+static int rs_check_takeover(struct raid_set *rs)
+{
+       struct mddev *mddev = &rs->md;
+       unsigned int near_copies;
+
+       if (rs->md.degraded) {
+               rs->ti->error = "Can't takeover degraded raid set";
+               return -EPERM;
+       }
+
+       if (rs_is_reshaping(rs)) {
+               rs->ti->error = "Can't takeover reshaping raid set";
+               return -EPERM;
+       }
+
+       switch (mddev->level) {
+       case 0:
+               /* raid0 -> raid1/5 with one disk */
+               if ((mddev->new_level == 1 || mddev->new_level == 5) &&
+                   mddev->raid_disks == 1)
+                       return 0;
+
+               /* raid0 -> raid10 */
+               if (mddev->new_level == 10 &&
+                   !(rs->raid_disks % mddev->raid_disks))
+                       return 0;
+
+               /* raid0 with multiple disks -> raid4/5/6 */
+               if (__within_range(mddev->new_level, 4, 6) &&
+                   mddev->new_layout == ALGORITHM_PARITY_N &&
+                   mddev->raid_disks > 1)
+                       return 0;
+
+               break;
+
+       case 10:
+               /* Can't takeover raid10_offset! */
+               if (__is_raid10_offset(mddev->layout))
+                       break;
+
+               near_copies = __raid10_near_copies(mddev->layout);
+
+               /* raid10* -> raid0 */
+               if (mddev->new_level == 0) {
+                       /* Can takeover raid10_near with raid disks divisable by data copies! */
+                       if (near_copies > 1 &&
+                           !(mddev->raid_disks % near_copies)) {
+                               mddev->raid_disks /= near_copies;
+                               mddev->delta_disks = mddev->raid_disks;
+                               return 0;
+                       }
+
+                       /* Can takeover raid10_far */
+                       if (near_copies == 1 &&
+                           __raid10_far_copies(mddev->layout) > 1)
+                               return 0;
+
+                       break;
+               }
+
+               /* raid10_{near,far} -> raid1 */
+               if (mddev->new_level == 1 &&
+                   max(near_copies, __raid10_far_copies(mddev->layout)) == mddev->raid_disks)
+                       return 0;
+
+               /* raid10_{near,far} with 2 disks -> raid4/5 */
+               if (__within_range(mddev->new_level, 4, 5) &&
+                   mddev->raid_disks == 2)
+                       return 0;
+               break;
+
+       case 1:
+               /* raid1 with 2 disks -> raid4/5 */
+               if (__within_range(mddev->new_level, 4, 5) &&
+                   mddev->raid_disks == 2) {
+                       mddev->degraded = 1;
+                       return 0;
+               }
+
+               /* raid1 -> raid0 */
+               if (mddev->new_level == 0 &&
+                   mddev->raid_disks == 1)
+                       return 0;
+
+               /* raid1 -> raid10 */
+               if (mddev->new_level == 10)
+                       return 0;
+               break;
+
+       case 4:
+               /* raid4 -> raid0 */
+               if (mddev->new_level == 0)
+                       return 0;
+
+               /* raid4 -> raid1/5 with 2 disks */
+               if ((mddev->new_level == 1 || mddev->new_level == 5) &&
+                   mddev->raid_disks == 2)
+                       return 0;
+
+               /* raid4 -> raid5/6 with parity N */
+               if (__within_range(mddev->new_level, 5, 6) &&
+                   mddev->layout == ALGORITHM_PARITY_N)
+                       return 0;
+               break;
+
+       case 5:
+               /* raid5 with parity N -> raid0 */
+               if (mddev->new_level == 0 &&
+                   mddev->layout == ALGORITHM_PARITY_N)
+                       return 0;
+
+               /* raid5 with parity N -> raid4 */
+               if (mddev->new_level == 4 &&
+                   mddev->layout == ALGORITHM_PARITY_N)
+                       return 0;
+
+               /* raid5 with 2 disks -> raid1/4/10 */
+               if ((mddev->new_level == 1 || mddev->new_level == 4 || mddev->new_level == 10) &&
+                   mddev->raid_disks == 2)
+                       return 0;
+
+               /* raid5_* ->  raid6_*_6 with Q-Syndrome N (e.g. raid5_ra -> raid6_ra_6 */
+               if (mddev->new_level == 6 &&
+                   ((mddev->layout == ALGORITHM_PARITY_N && mddev->new_layout == ALGORITHM_PARITY_N) ||
+                     __within_range(mddev->new_layout, ALGORITHM_LEFT_ASYMMETRIC_6, ALGORITHM_RIGHT_SYMMETRIC_6)))
+                       return 0;
+               break;
+
+       case 6:
+               /* raid6 with parity N -> raid0 */
+               if (mddev->new_level == 0 &&
+                   mddev->layout == ALGORITHM_PARITY_N)
+                       return 0;
+
+               /* raid6 with parity N -> raid4 */
+               if (mddev->new_level == 4 &&
+                   mddev->layout == ALGORITHM_PARITY_N)
+                       return 0;
+
+               /* raid6_*_n with Q-Syndrome N -> raid5_* */
+               if (mddev->new_level == 5 &&
+                   ((mddev->layout == ALGORITHM_PARITY_N && mddev->new_layout == ALGORITHM_PARITY_N) ||
+                    __within_range(mddev->new_layout, ALGORITHM_LEFT_ASYMMETRIC, ALGORITHM_RIGHT_SYMMETRIC)))
+                       return 0;
+
+       default:
+               break;
+       }
+
+       rs->ti->error = "takeover not possible";
+       return -EINVAL;
+}
+
+/* True if @rs requested to be taken over */
+static bool rs_takeover_requested(struct raid_set *rs)
+{
+       return rs->md.new_level != rs->md.level;
+}
+
+/* True if @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 (!mddev->level)
+               return false;
+
+       change = mddev->new_layout != mddev->layout ||
+                mddev->new_chunk_sectors != mddev->chunk_sectors ||
+                rs->delta_disks;
+
+       /* Historical case to support raid1 reshape without delta disks */
+       if (mddev->level == 1) {
+               if (rs->delta_disks)
+                       return !!rs->delta_disks;
+
+               return !change &&
+                      mddev->raid_disks != rs->raid_disks;
+       }
+
+       if (mddev->level == 10)
+               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.
@@ -755,13 +1744,14 @@ static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
 #define DM_RAID_MAGIC 0x64526D44
 struct dm_raid_superblock {
        __le32 magic;           /* "DmRd" */
-       __le32 features;        /* Used to indicate possible future changes */
+       __le32 compat_features; /* Used to indicate compatible features (like 1.9.0 ondisk metadata extension) */
 
-       __le32 num_devices;     /* Number of devices in this array. (Max 64) */
-       __le32 array_position;  /* The position of this drive in the array */
+       __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;  /* Bit field of devices to indicate failures */
+       __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
@@ -770,21 +1760,95 @@ struct dm_raid_superblock {
        __le64 disk_recovery_offset;
 
        /*
-        * This offset tracks the progress of the initial array
+        * This offset tracks the progress of the initial raid set
         * synchronisation/parity calculation.
         */
        __le64 array_resync_offset;
 
        /*
-        * RAID characteristics
+        * raid characteristics
         */
        __le32 level;
        __le32 layout;
        __le32 stripe_sectors;
 
-       /* Remainder of a logical block is zero-filled when writing (see super_sync()). */
+       /********************************************************************
+        * BELOW FOLLOW V1.9.0 EXTENSIONS TO THE PRISTINE SUPERBLOCK FORMAT!!!
+        *
+        * FEATURE_FLAG_SUPPORTS_V190 in the features member indicates that those exist
+        */
+
+       __le32 flags; /* Flags defining array states for reshaping */
+
+       /*
+        * This offset tracks the progress of a raid
+        * set reshape in order to be able to restart it
+        */
+       __le64 reshape_position;
+
+       /*
+        * These define the properties of the array in case of an interrupted reshape
+        */
+       __le32 new_level;
+       __le32 new_layout;
+       __le32 new_stripe_sectors;
+       __le32 delta_disks;
+
+       __le64 array_sectors; /* Array size in sectors */
+
+       /*
+        * Sector offsets to data on devices (reshaping).
+        * Needed to support out of place reshaping, thus
+        * not writing over any stripes whilst converting
+        * them from old to new layout
+        */
+       __le64 data_offset;
+       __le64 new_data_offset;
+
+       __le64 sectors; /* Used device size in sectors */
+
+       /*
+        * Additonal Bit field of devices indicating failures to support
+        * up to 256 devices with the 1.9.0 on-disk metadata format
+        */
+       __le64 extended_failed_devices[DISKS_ARRAY_ELEMS - 1];
+
+       __le32 incompat_features;       /* Used to indicate any incompatible features */
+
+       /* Always set rest up to logical block size to 0 when writing (see get_metadata_device() below). */
 } __packed;
 
+/*
+ * Check for reshape constraints on raid set @rs:
+ *
+ * - reshape function non-existent
+ * - degraded set
+ * - ongoing recovery
+ * - ongoing reshape
+ *
+ * Returns 0 if none or -EPERM if given constraint
+ * and error message reference in @errmsg
+ */
+static int rs_check_reshape(struct raid_set *rs)
+{
+       struct mddev *mddev = &rs->md;
+
+       if (!mddev->pers || !mddev->pers->check_reshape)
+               rs->ti->error = "Reshape not supported";
+       else if (mddev->degraded)
+               rs->ti->error = "Can't reshape degraded raid set";
+       else if (rs_is_recovering(rs))
+               rs->ti->error = "Convert request on recovering raid set prohibited";
+       else if (rs_is_reshaping(rs))
+               rs->ti->error = "raid set already reshaping!";
+       else if (!(rs_is_raid1(rs) || rs_is_raid10(rs) || rs_is_raid456(rs)))
+               rs->ti->error = "Reshaping only supported for raid1/4/5/6/10";
+       else
+               return 0;
+
+       return -EPERM;
+}
+
 static int read_disk_sb(struct md_rdev *rdev, int size)
 {
        BUG_ON(!rdev->sb_page);
@@ -792,7 +1856,7 @@ static int read_disk_sb(struct md_rdev *rdev, int size)
        if (rdev->sb_loaded)
                return 0;
 
-       if (!sync_page_io(rdev, 0, size, rdev->sb_page, READ, 1)) {
+       if (!sync_page_io(rdev, 0, size, rdev->sb_page, REQ_OP_READ, 0, true)) {
                DMERR("Failed to read superblock of device at position %d",
                      rdev->raid_disk);
                md_error(rdev->mddev, rdev);
@@ -804,31 +1868,67 @@ static int read_disk_sb(struct md_rdev *rdev, int size)
        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)
 {
-       int i;
-       uint64_t failed_devices;
+       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);
-       failed_devices = le64_to_cpu(sb->failed_devices);
 
-       for (i = 0; i < mddev->raid_disks; i++)
-               if (!rs->dev[i].data_dev ||
-                   test_bit(Faulty, &(rs->dev[i].rdev.flags)))
-                       failed_devices |= (1ULL << i);
+       sb_retrieve_failed_devices(sb, failed_devices);
 
-       memset(sb + 1, 0, rdev->sb_size - sizeof(*sb));
+       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->features = cpu_to_le32(0);  /* No features yet */
+       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->failed_devices = cpu_to_le64(failed_devices);
 
        sb->disk_recovery_offset = cpu_to_le64(rdev->recovery_offset);
        sb->array_resync_offset = cpu_to_le64(mddev->recovery_cp);
@@ -836,6 +1936,33 @@ static void super_sync(struct mddev *mddev, struct md_rdev *rdev)
        sb->level = cpu_to_le32(mddev->level);
        sb->layout = cpu_to_le32(mddev->layout);
        sb->stripe_sectors = cpu_to_le32(mddev->chunk_sectors);
+
+       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);
+
+       /* Zero out the rest of the payload after the size of the superblock */
+       memset(sb + 1, 0, rdev->sb_size - sizeof(*sb));
 }
 
 /*
@@ -848,7 +1975,7 @@ static void super_sync(struct mddev *mddev, struct md_rdev *rdev)
  */
 static int super_load(struct md_rdev *rdev, struct md_rdev *refdev)
 {
-       int ret;
+       int r;
        struct dm_raid_superblock *sb;
        struct dm_raid_superblock *refsb;
        uint64_t events_sb, events_refsb;
@@ -860,9 +1987,9 @@ static int super_load(struct md_rdev *rdev, struct md_rdev *refdev)
                return -EINVAL;
        }
 
-       ret = read_disk_sb(rdev, rdev->sb_size);
-       if (ret)
-               return ret;
+       r = read_disk_sb(rdev, rdev->sb_size);
+       if (r)
+               return r;
 
        sb = page_address(rdev->sb_page);
 
@@ -876,6 +2003,7 @@ static int super_load(struct md_rdev *rdev, struct md_rdev *refdev)
                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_CHANGE_DEVS, &rdev->mddev->flags);
@@ -895,129 +2023,212 @@ static int super_load(struct md_rdev *rdev, struct md_rdev *refdev)
        return (events_sb > events_refsb) ? 1 : 0;
 }
 
-static int super_init_validation(struct mddev *mddev, struct md_rdev *rdev)
+static int super_init_validation(struct raid_set *rs, struct md_rdev *rdev)
 {
        int role;
-       struct raid_set *rs = container_of(mddev, struct raid_set, md);
+       unsigned int d;
+       struct mddev *mddev = &rs->md;
        uint64_t events_sb;
-       uint64_t failed_devices;
+       uint64_t failed_devices[DISKS_ARRAY_ELEMS];
        struct dm_raid_superblock *sb;
-       uint32_t new_devs = 0;
-       uint32_t rebuilds = 0;
+       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);
-       failed_devices = le64_to_cpu(sb->failed_devices);
 
        /*
         * Initialise to 1 if this is a new superblock.
         */
        mddev->events = events_sb ? : 1;
 
+       mddev->reshape_position = MaxSector;
+
        /*
-        * Reshaping is not currently allowed
+        * Reshaping is supported, e.g. reshape_position is valid
+        * in superblock and superblock content is authoritative.
         */
-       if (le32_to_cpu(sb->level) != mddev->level) {
-               DMERR("Reshaping arrays not yet supported. (RAID level change)");
-               return -EINVAL;
-       }
-       if (le32_to_cpu(sb->layout) != mddev->layout) {
-               DMERR("Reshaping arrays not yet supported. (RAID layout change)");
-               DMERR("  0x%X vs 0x%X", le32_to_cpu(sb->layout), mddev->layout);
-               DMERR("  Old layout: %s w/ %d copies",
-                     raid10_md_layout_to_format(le32_to_cpu(sb->layout)),
-                     raid10_md_layout_to_copies(le32_to_cpu(sb->layout)));
-               DMERR("  New layout: %s w/ %d copies",
-                     raid10_md_layout_to_format(mddev->layout),
-                     raid10_md_layout_to_copies(mddev->layout));
-               return -EINVAL;
-       }
-       if (le32_to_cpu(sb->stripe_sectors) != mddev->chunk_sectors) {
-               DMERR("Reshaping arrays not yet supported. (stripe sectors change)");
-               return -EINVAL;
-       }
+       if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190) {
+               /* Superblock is authoritative wrt given raid set layout! */
+               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);
+               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;
+                       }
 
-       /* We can only change the number of devices in RAID1 right now */
-       if ((rs->raid_type->level != 1) &&
-           (le32_to_cpu(sb->num_devices) != mddev->raid_disks)) {
-               DMERR("Reshaping arrays not yet supported. (device count change)");
-               return -EINVAL;
+                       if (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
+                */
+               if (le32_to_cpu(sb->level) != mddev->level) {
+                       DMERR("Reshaping/takeover raid sets not yet supported. (raid level/stripes/size change)");
+                       return -EINVAL;
+               }
+               if (le32_to_cpu(sb->layout) != mddev->layout) {
+                       DMERR("Reshaping raid sets not yet supported. (raid layout change)");
+                       DMERR("  0x%X vs 0x%X", le32_to_cpu(sb->layout), mddev->layout);
+                       DMERR("  Old layout: %s w/ %d copies",
+                             raid10_md_layout_to_format(le32_to_cpu(sb->layout)),
+                             raid10_md_layout_to_copies(le32_to_cpu(sb->layout)));
+                       DMERR("  New layout: %s w/ %d copies",
+                             raid10_md_layout_to_format(mddev->layout),
+                             raid10_md_layout_to_copies(mddev->layout));
+                       return -EINVAL;
+               }
+               if (le32_to_cpu(sb->stripe_sectors) != mddev->chunk_sectors) {
+                       DMERR("Reshaping raid sets not yet supported. (stripe sectors change)");
+                       return -EINVAL;
+               }
+
+               /* We can only change the number of devices in raid1 with old (i.e. pre 1.0.7) metadata */
+               if (!rt_is_raid1(rs->raid_type) &&
+                   (le32_to_cpu(sb->num_devices) != mddev->raid_disks)) {
+                       DMERR("Reshaping raid sets not yet supported. (device count change from %u to %u)",
+                             sb->num_devices, mddev->raid_disks);
+                       return -EINVAL;
+               }
+
+               /* Table line is checked vs. authoritative superblock */
+               rs_set_new(rs);
        }
 
-       if (!(rs->ctr_flags & (CTR_FLAG_SYNC | CTR_FLAG_NOSYNC)))
+       if (!test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))
                mddev->recovery_cp = le64_to_cpu(sb->array_resync_offset);
 
        /*
         * During load, we set FirstUse if a new superblock was written.
         * There are two reasons we might not have a superblock:
-        * 1) The array is brand new - in which case, all of the
-        *    devices must have their In_sync bit set.  Also,
+        * 1) The raid set is brand new - in which case, all of the
+        *    devices must have their In_sync bit set.  Also,
         *    recovery_cp must be 0, unless forced.
-        * 2) This is a new device being added to an old array
+        * 2) This is a new device being added to an old raid set
         *    and the new device needs to be rebuilt - in which
         *    case the In_sync bit will /not/ be set and
         *    recovery_cp must be MaxSector.
+        * 3) This is/are a new device(s) being added to an old
+        *    raid set during takeover to a higher raid level
+        *    to provide capacity for redundancy or during reshape
+        *    to add capacity to grow the raid set.
         */
+       d = 0;
        rdev_for_each(r, mddev) {
+               if (test_bit(FirstUse, &r->flags))
+                       new_devs++;
+
                if (!test_bit(In_sync, &r->flags)) {
-                       DMINFO("Device %d specified for rebuild: "
-                              "Clearing superblock", r->raid_disk);
+                       DMINFO("Device %d specified for rebuild; clearing superblock",
+                               r->raid_disk);
                        rebuilds++;
-               } else if (test_bit(FirstUse, &r->flags))
-                       new_devs++;
+
+                       if (test_bit(FirstUse, &r->flags))
+                               rebuild_and_new++;
+               }
+
+               d++;
        }
 
-       if (!rebuilds) {
-               if (new_devs == mddev->raid_disks) {
-                       DMINFO("Superblocks created for new array");
+       if (new_devs == rs->raid_disks || !rebuilds) {
+               /* Replace a broken device */
+               if (new_devs == 1 && !rs->delta_disks)
+                       ;
+               if (new_devs == rs->raid_disks) {
+                       DMINFO("Superblocks created for new raid set");
                        set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
-               } else if (new_devs) {
-                       DMERR("New device injected "
-                             "into existing array without 'rebuild' "
-                             "parameter specified");
+               } 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) {
-               DMERR("'rebuild' devices cannot be "
-                     "injected into an array with other first-time devices");
-               return -EINVAL;
-       } else if (mddev->recovery_cp != MaxSector) {
-               DMERR("'rebuild' specified while array is not in-sync");
+       } 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 (rs_is_recovering(rs)) {
+                       DMERR("'rebuild' specified while raid set is not in-sync (recovery_cp=%llu)",
+                             (unsigned long long) mddev->recovery_cp);
+                       return -EINVAL;
+               } else if (rs_is_reshaping(rs)) {
+                       DMERR("'rebuild' specified while raid set is being reshaped (reshape_position=%llu)",
+                             (unsigned long long) mddev->reshape_position);
+                       return -EINVAL;
+               }
        }
 
        /*
         * Now we set the Faulty bit for those devices that are
         * recorded in the superblock as failed.
         */
+       sb_retrieve_failed_devices(sb, failed_devices);
        rdev_for_each(r, mddev) {
                if (!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->raid_type->level != 1) {
-                                       rs->ti->error = "Cannot change device "
-                                               "positions in RAID array";
+                               if (__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("RAID1 device #%d now at position #%d",
-                                      role, r->raid_disk);
+
+                               DMINFO("raid device #%d now at position #%d", role, r->raid_disk);
                        }
 
                        /*
                         * Partial recovery is performed on
                         * returning failed devices.
                         */
-                       if (failed_devices & (1 << role))
+                       if (test_bit(role, (void *) failed_devices))
                                set_bit(Faulty, &r->flags);
                }
        }
@@ -1028,41 +2239,60 @@ static int super_init_validation(struct mddev *mddev, struct md_rdev *rdev)
 static int super_validate(struct raid_set *rs, struct md_rdev *rdev)
 {
        struct mddev *mddev = &rs->md;
-       struct dm_raid_superblock *sb = page_address(rdev->sb_page);
+       struct dm_raid_superblock *sb;
+
+       if (rs_is_raid0(rs) || !rdev->sb_page)
+               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(mddev, rdev))
+       if (!mddev->events && super_init_validation(rs, rdev))
+               return -EINVAL;
+
+       if (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 (le32_to_cpu(sb->features)) {
-               rs->ti->error = "Unable to assemble array: No feature flags supported yet";
+       if (sb->incompat_features) {
+               rs->ti->error = "Unable to assemble array: No incompatible feature flags supported yet";
                return -EINVAL;
        }
 
        /* Enable bitmap creation for RAID levels != 0 */
-       mddev->bitmap_info.offset = (rs->raid_type->level) ? to_sector(4096) : 0;
+       mddev->bitmap_info.offset = rt_is_raid0(rs->raid_type) ? 0 : to_sector(4096);
        rdev->mddev->bitmap_info.default_offset = mddev->bitmap_info.offset;
 
-       if (!test_bit(FirstUse, &rdev->flags)) {
+       if (!test_and_clear_bit(FirstUse, &rdev->flags)) {
+               /* Retrieve device size stored in superblock to be prepared for shrink */
+               rdev->sectors = le64_to_cpu(sb->sectors);
                rdev->recovery_offset = le64_to_cpu(sb->disk_recovery_offset);
-               if (rdev->recovery_offset != MaxSector)
-                       clear_bit(In_sync, &rdev->flags);
+               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_bit(Faulty, &rdev->flags)) {
-               clear_bit(Faulty, &rdev->flags);
+       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;
-               rdev->recovery_offset = 0;
        }
 
-       clear_bit(FirstUse, &rdev->flags);
+       /* Reshape support -> restore repective data offsets */
+       rdev->data_offset = le64_to_cpu(sb->data_offset);
+       rdev->new_data_offset = le64_to_cpu(sb->new_data_offset);
 
        return 0;
 }
@@ -1072,7 +2302,7 @@ static int super_validate(struct raid_set *rs, struct md_rdev *rdev)
  */
 static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
 {
-       int ret;
+       int r;
        struct raid_dev *dev;
        struct md_rdev *rdev, *tmp, *freshest;
        struct mddev *mddev = &rs->md;
@@ -1082,24 +2312,22 @@ static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
                /*
                 * 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
+                * though it were new.  This is the intended effect
                 * of the "sync" directive.
                 *
                 * When reshaping capability is added, we must ensure
                 * that the "sync" directive is disallowed during the
                 * reshape.
                 */
-               rdev->sectors = to_sector(i_size_read(rdev->bdev->bd_inode));
-
-               if (rs->ctr_flags & CTR_FLAG_SYNC)
+               if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags))
                        continue;
 
                if (!rdev->meta_bdev)
                        continue;
 
-               ret = super_load(rdev, freshest);
+               r = super_load(rdev, freshest);
 
-               switch (ret) {
+               switch (r) {
                case 1:
                        freshest = rdev;
                        break;
@@ -1116,57 +2344,368 @@ static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
                        if (rdev->sb_page)
                                put_page(rdev->sb_page);
 
-                       rdev->sb_page = NULL;
+                       rdev->sb_page = NULL;
+
+                       rdev->sb_loaded = 0;
+
+                       /*
+                        * We might be able to salvage the data device
+                        * even though the meta device has failed.  For
+                        * now, we behave as though '- -' had been
+                        * set for this device in the table.
+                        */
+                       if (dev->data_dev)
+                               dm_put_device(ti, dev->data_dev);
+
+                       dev->data_dev = NULL;
+                       rdev->bdev = NULL;
+
+                       list_del(&rdev->same_set);
+               }
+       }
+
+       if (!freshest)
+               return 0;
+
+       if (validate_raid_redundancy(rs)) {
+               rs->ti->error = "Insufficient redundancy to activate array";
+               return -EINVAL;
+       }
+
+       /*
+        * Validation of the freshest device provides the source of
+        * validation for the remaining devices.
+        */
+       rs->ti->error = "Unable to assemble array: Invalid superblocks";
+       if (super_validate(rs, freshest))
+               return -EINVAL;
+
+       rdev_for_each(rdev, mddev)
+               if ((rdev != freshest) && super_validate(rs, rdev))
+                       return -EINVAL;
+       return 0;
+}
+
+/*
+ * Adjust data_offset and new_data_offset on all disk members of @rs
+ * for out of place reshaping if requested by contructor
+ *
+ * We need free space at the beginning of each raid disk for forward
+ * and at the end for backward reshapes which userspace has to provide
+ * via remapping/reordering of space.
+ */
+static int rs_adjust_data_offsets(struct raid_set *rs)
+{
+       sector_t data_offset = 0, new_data_offset = 0;
+       struct md_rdev *rdev;
+
+       /* Constructor did not request data offset change */
+       if (!test_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
+               if (!rs_is_reshapable(rs))
+                       goto out;
+
+               return 0;
+       }
+
+       /* HM FIXME: get InSync raid_dev? */
+       rdev = &rs->dev[0].rdev;
+
+       if (rs->delta_disks < 0) {
+               /*
+                * Removing disks (reshaping backwards):
+                *
+                * - before reshape: data is at offset 0 and free space
+                *                   is at end of each component LV
+                *
+                * - after reshape: data is at offset rs->data_offset != 0 on each component LV
+                */
+               data_offset = 0;
+               new_data_offset = rs->data_offset;
+
+       } else if (rs->delta_disks > 0) {
+               /*
+                * Adding disks (reshaping forwards):
+                *
+                * - before reshape: data is at offset rs->data_offset != 0 and
+                *                   free space is at begin of each component LV
+                *
+                * - after reshape: data is at offset 0 on each component LV
+                */
+               data_offset = rs->data_offset;
+               new_data_offset = 0;
+
+       } else {
+               /*
+                * User space passes in 0 for data offset after having removed reshape space
+                *
+                * - or - (data offset != 0)
+                *
+                * Changing RAID layout or chunk size -> toggle offsets
+                *
+                * - before reshape: data is at offset rs->data_offset 0 and
+                *                   free space is at end of each component LV
+                *                   -or-
+                *                   data is at offset rs->data_offset != 0 and
+                *                   free space is at begin of each component LV
+                *
+                * - after reshape: data is at offset 0 if it was at offset != 0
+                *                  or at offset != 0 if it was at offset 0
+                *                  on each component LV
+                *
+                */
+               data_offset = rs->data_offset ? rdev->data_offset : 0;
+               new_data_offset = data_offset ? 0 : rs->data_offset;
+               set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+       }
+
+       /*
+        * Make sure we got a minimum amount of free sectors per device
+        */
+       if (rs->data_offset &&
+           to_sector(i_size_read(rdev->bdev->bd_inode)) - rdev->sectors < MIN_FREE_RESHAPE_SPACE) {
+               rs->ti->error = data_offset ? "No space for forward reshape" :
+                                             "No space for backward reshape";
+               return -ENOSPC;
+       }
+out:
+       /* Adjust data offsets on all rdevs */
+       rdev_for_each(rdev, &rs->md) {
+               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) {
+               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 (mddev->level == 0) {
+                       /* 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 (mddev->level == 1)
+                       /* raid1 -> raid10_near layout */
+                       mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
+                                                                  rs->raid_disks);
+               else
+                       return -EINVAL;
+
+       }
+
+       clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
+       mddev->recovery_cp = MaxSector;
+
+       while (d--) {
+               rdev = &rs->dev[d].rdev;
+
+               if (test_bit(d, (void *) rs->rebuild_disks)) {
+                       clear_bit(In_sync, &rdev->flags);
+                       clear_bit(Faulty, &rdev->flags);
+                       mddev->recovery_cp = rdev->recovery_offset = 0;
+                       /* Bitmap has to be created when we do an "up" takeover */
+                       set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
+               }
+
+               rdev->new_data_offset = new_data_offset;
+       }
+
+       return 0;
+}
+
+/* Prepare @rs for reshape */
+static int rs_prepare_reshape(struct raid_set *rs)
+{
+       bool reshape;
+       struct mddev *mddev = &rs->md;
+
+       if (rs_is_raid10(rs)) {
+               if (rs->raid_disks != mddev->raid_disks &&
+                   __is_raid10_near(mddev->layout) &&
+                   rs->raid10_copies &&
+                   rs->raid10_copies != __raid10_near_copies(mddev->layout)) {
+                       /*
+                        * raid disk have to be multiple of data copies to allow this conversion,
+                        *
+                        * This is actually not a reshape it is a
+                        * rebuild of any additional mirrors per group
+                        */
+                       if (rs->raid_disks % rs->raid10_copies) {
+                               rs->ti->error = "Can't reshape raid10 mirror groups";
+                               return -EINVAL;
+                       }
+
+                       /* Userpace reordered disks to add/remove mirrors -> adjust raid_disk indexes */
+                       __reorder_raid_disk_indexes(rs);
+                       mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
+                                                                  rs->raid10_copies);
+                       mddev->new_layout = mddev->layout;
+                       reshape = false;
+               } else
+                       reshape = true;
+
+       } else if (rs_is_raid456(rs))
+               reshape = true;
+
+       else if (rs_is_raid1(rs)) {
+               if (rs->delta_disks) {
+                       /* Process raid1 via delta_disks */
+                       mddev->degraded = rs->delta_disks < 0 ? -rs->delta_disks : rs->delta_disks;
+                       reshape = true;
+               } else {
+                       /* Process raid1 without delta_disks */
+                       mddev->raid_disks = rs->raid_disks;
+                       set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
+                       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);
+               set_bit(RT_FLAG_KEEP_RS_FROZEN, &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;
+}
+
+/*
+ *
+ * - 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;
+       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 disks, array size has
+        *   to grow after the disk adding reshape,
+        *   which'll hapen in the event handler;
+        *   reshape will happen forward, so space has to
+        *   be available at the beginning of each disk
+        *
+        * - in case of removing disks, 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
+        */
 
-                       rdev->sb_loaded = 0;
+       /* 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);
 
                        /*
-                        * We might be able to salvage the data device
-                        * even though the meta device has failed.  For
-                        * now, we behave as though '- -' had been
-                        * set for this device in the table.
+                        * 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
                         */
-                       if (dev->data_dev)
-                               dm_put_device(ti, dev->data_dev);
-
-                       dev->data_dev = NULL;
-                       rdev->bdev = NULL;
+                       rdev->saved_raid_disk = -1;
+                       rdev->raid_disk = d;
 
-                       list_del(&rdev->same_set);
+                       rdev->sectors = mddev->dev_sectors;
+                       rdev->recovery_offset = rs_is_raid1(rs) ? 0 : MaxSector;
                }
-       }
 
-       if (!freshest)
-               return 0;
-
-       if (validate_raid_redundancy(rs)) {
-               rs->ti->error = "Insufficient redundancy to activate array";
-               return -EINVAL;
-       }
+               mddev->reshape_backwards = 0; /* adding disks -> forward reshape */
 
-       /*
-        * Validation of the freshest device provides the source of
-        * validation for the remaining devices.
-        */
-       ti->error = "Unable to assemble array: Invalid superblocks";
-       if (super_validate(rs, freshest))
-               return -EINVAL;
+       /* Remove disk(s) */
+       } else if (rs->delta_disks < 0) {
+               r = rs_set_dev_and_array_sectors(rs, true);
+               mddev->reshape_backwards = 1; /* removing disk(s) -> backward reshape */
 
-       rdev_for_each(rdev, mddev)
-               if ((rdev != freshest) && super_validate(rs, rdev))
-                       return -EINVAL;
+       /* 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;
+       }
 
-       return 0;
+       return r;
 }
 
 /*
  * Enable/disable discard support on RAID set depending on
  * RAID level and discard properties of underlying RAID members.
  */
-static void configure_discard_support(struct dm_target *ti, struct raid_set *rs)
+static void configure_discard_support(struct raid_set *rs)
 {
        int i;
        bool raid456;
+       struct dm_target *ti = rs->ti;
 
        /* Assume discards not supported until after checks below. */
        ti->discards_supported = false;
@@ -1174,7 +2713,7 @@ static void configure_discard_support(struct dm_target *ti, struct raid_set *rs)
        /* RAID level 4,5,6 require discard_zeroes_data for data integrity! */
        raid456 = (rs->md.level == 4 || rs->md.level == 5 || rs->md.level == 6);
 
-       for (i = 0; i < rs->md.raid_disks; i++) {
+       for (i = 0; i < rs->raid_disks; i++) {
                struct request_queue *q;
 
                if (!rs->dev[i].rdev.bdev)
@@ -1207,118 +2746,252 @@ static void configure_discard_support(struct dm_target *ti, struct raid_set *rs)
 }
 
 /*
- * Construct a RAID4/5/6 mapping:
+ * Construct a RAID0/1/10/4/5/6 mapping:
  * Args:
- *     <raid_type> <#raid_params> <raid_params>                \
- *     <#raid_devs> { <meta_dev1> <dev1> .. <meta_devN> <devN> }
+ *     <raid_type> <#raid_params> <raid_params>{0,}    \
+ *     <#raid_devs> [<meta_dev1> <dev1>]{1,}
  *
- * <raid_params> varies by <raid_type>.  See 'parse_raid_params' for
+ * <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 argc, char **argv)
+static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
-       int ret;
+       int r;
+       bool resize;
        struct raid_type *rt;
-       unsigned long num_raid_params, num_raid_devs;
+       unsigned int num_raid_params, num_raid_devs;
+       sector_t calculated_dev_sectors;
        struct raid_set *rs = NULL;
-
-       /* Must have at least <raid_type> <#raid_params> */
-       if (argc < 2) {
-               ti->error = "Too few arguments";
+       const char *arg;
+       struct rs_layout rs_layout;
+       struct dm_arg_set as = { argc, argv }, as_nrd;
+       struct dm_arg _args[] = {
+               { 0, as.argc, "Cannot understand number of raid parameters" },
+               { 1, 254, "Cannot understand number of raid devices parameters" }
+       };
+
+       /* Must have <raid_type> */
+       arg = dm_shift_arg(&as);
+       if (!arg) {
+               ti->error = "No arguments";
                return -EINVAL;
        }
 
-       /* raid type */
-       rt = get_raid_type(argv[0]);
+       rt = get_raid_type(arg);
        if (!rt) {
                ti->error = "Unrecognised raid_type";
                return -EINVAL;
        }
-       argc--;
-       argv++;
 
-       /* number of RAID parameters */
-       if (kstrtoul(argv[0], 10, &num_raid_params) < 0) {
-               ti->error = "Cannot understand number of RAID parameters";
+       /* Must have <#raid_params> */
+       if (dm_read_arg_group(_args, &as, &num_raid_params, &ti->error))
                return -EINVAL;
-       }
-       argc--;
-       argv++;
-
-       /* Skip over RAID params for now and find out # of devices */
-       if (num_raid_params >= argc) {
-               ti->error = "Arguments do not agree with counts given";
-               return -EINVAL;
-       }
 
-       if ((kstrtoul(argv[num_raid_params], 10, &num_raid_devs) < 0) ||
-           (num_raid_devs > MAX_RAID_DEVICES)) {
-               ti->error = "Cannot understand number of raid devices";
+       /* 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;
-       }
 
-       argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */
-       if (argc != (num_raid_devs * 2)) {
-               ti->error = "Supplied RAID devices does not match the count given";
+       if (!__within_range(num_raid_devs, 1, MAX_RAID_DEVICES)) {
+               ti->error = "Invalid number of supplied raid devices";
                return -EINVAL;
        }
 
-       rs = context_alloc(ti, rt, (unsigned)num_raid_devs);
+       rs = raid_set_alloc(ti, rt, num_raid_devs);
        if (IS_ERR(rs))
                return PTR_ERR(rs);
 
-       ret = parse_raid_params(rs, argv, (unsigned)num_raid_params);
-       if (ret)
+       r = parse_raid_params(rs, &as, num_raid_params);
+       if (r)
                goto bad;
 
-       argv += num_raid_params + 1;
-
-       ret = dev_parms(rs, argv);
-       if (ret)
+       r = parse_dev_params(rs, &as);
+       if (r)
                goto bad;
 
        rs->md.sync_super = super_sync;
-       ret = analyse_superblocks(ti, rs);
-       if (ret)
+
+       /*
+        * Calculate ctr requested array and device sizes to allow
+        * for superblock analysis needing device sizes defined.
+        *
+        * Any existing superblock will overwrite the array and device sizes
+        */
+       r = rs_set_dev_and_array_sectors(rs, false);
+       if (r)
+               goto bad;
+
+       calculated_dev_sectors = rs->dev[0].rdev.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;
 
+       resize = calculated_dev_sectors != rs->dev[0].rdev.sectors;
+
        INIT_WORK(&rs->md.event_work, do_table_event);
        ti->private = rs;
        ti->num_flush_bios = 1;
 
+       /* Restore any requested new layout for conversion decision */
+       rs_config_restore(rs, &rs_layout);
+
        /*
-        * Disable/enable discard support on RAID set.
+        * 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.
         */
-       configure_discard_support(ti, rs);
+       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 */
+               ; /* skip setup rs */
+       } else if (rs_is_reshaping(rs)) {
+               /* Have to reject size change request during reshape */
+               if (resize) {
+                       ti->error = "Can't resize a reshaping raid set";
+                       r = -EPERM;
+                       goto bad;
+               }
+               /* skip setup rs */
+       } else if (rs_takeover_requested(rs)) {
+               if (rs_is_reshaping(rs)) {
+                       ti->error = "Can't takeover a reshaping raid set";
+                       r = -EPERM;
+                       goto bad;
+               }
+
+               /*
+                * If a takeover is needed, userspace sets any additional
+                * devices to rebuild and we can check for a valid request here.
+                *
+                * If acceptible, set the level to the new requested
+                * one, prohibit requesting recovery, allow the raid
+                * set to run and store superblocks during resume.
+                */
+               r = rs_check_takeover(rs);
+               if (r)
+                       goto bad;
+
+               r = rs_setup_takeover(rs);
+               if (r)
+                       goto bad;
+
+               set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+               set_bit(RT_FLAG_KEEP_RS_FROZEN, &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)) {
+               /*
+                 * We can only prepare for a reshape here, because the
+                 * raid set needs to run to provide the repective reshape
+                 * check functions via its MD personality instance.
+                 *
+                 * So do the reshape check after md_run() succeeded.
+                 */
+               r = rs_prepare_reshape(rs);
+               if (r)
+                       return r;
+
+               /* Reshaping ain't recovery, so disable recovery */
+               rs_setup_recovery(rs, MaxSector);
+               rs_set_cur(rs);
+       } else {
+               /* May not set recovery when a device rebuild is requested */
+               if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags)) {
+                       rs_setup_recovery(rs, MaxSector);
+                       set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+               } else
+                       rs_setup_recovery(rs, test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) ?
+                                             0 : (resize ? calculated_dev_sectors : MaxSector));
+               rs_set_cur(rs);
+       }
+
+       /* If constructor requested it, change data and new_data offsets */
+       r = rs_adjust_data_offsets(rs);
+       if (r)
+               goto bad;
+
+       /* Start raid set read-only and assumed clean to change in raid_resume() */
+       rs->md.ro = 1;
+       rs->md.in_sync = 1;
+       set_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
 
        /* Has to be held on running the array */
        mddev_lock_nointr(&rs->md);
-       ret = md_run(&rs->md);
+       r = md_run(&rs->md);
        rs->md.in_sync = 0; /* Assume already marked dirty */
-       mddev_unlock(&rs->md);
 
-       if (ret) {
-               ti->error = "Fail to run raid array";
+       if (r) {
+               ti->error = "Failed to run raid array";
+               mddev_unlock(&rs->md);
                goto bad;
        }
 
-       if (ti->len != rs->md.array_sectors) {
-               ti->error = "Array size does not match requested target length";
-               ret = -EINVAL;
-               goto size_mismatch;
-       }
        rs->callbacks.congested_fn = raid_is_congested;
        dm_table_add_target_callbacks(ti->table, &rs->callbacks);
 
        mddev_suspend(&rs->md);
+
+       /* Try to adjust the raid4/5/6 stripe cache size to the stripe size */
+       if (rs_is_raid456(rs)) {
+               r = rs_set_raid456_stripe_cache(rs);
+               if (r)
+                       goto bad_stripe_cache;
+       }
+
+       /* Now do an early reshape check */
+       if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
+               r = rs_check_reshape(rs);
+               if (r)
+                       goto bad_check_reshape;
+
+               /* Restore new, ctr requested layout to perform check */
+               rs_config_restore(rs, &rs_layout);
+
+               if (rs->md.pers->start_reshape) {
+                       r = rs->md.pers->check_reshape(&rs->md);
+                       if (r) {
+                               ti->error = "Reshape check failed";
+                               goto bad_check_reshape;
+                       }
+               }
+       }
+
+       mddev_unlock(&rs->md);
        return 0;
 
-size_mismatch:
+bad_stripe_cache:
+bad_check_reshape:
        md_stop(&rs->md);
 bad:
-       context_free(rs);
+       raid_set_free(rs);
 
-       return ret;
+       return r;
 }
 
 static void raid_dtr(struct dm_target *ti)
@@ -1327,7 +3000,7 @@ static void raid_dtr(struct dm_target *ti)
 
        list_del_init(&rs->callbacks.list);
        md_stop(&rs->md);
-       context_free(rs);
+       raid_set_free(rs);
 }
 
 static int raid_map(struct dm_target *ti, struct bio *bio)
@@ -1335,11 +3008,23 @@ static int raid_map(struct dm_target *ti, struct bio *bio)
        struct raid_set *rs = ti->private;
        struct mddev *mddev = &rs->md;
 
+       /*
+        * If we're reshaping to add disk(s)), ti->len and
+        * mddev->array_sectors will differ during the process
+        * (ti->len > mddev->array_sectors), so we have to requeue
+        * bios with addresses > mddev->array_sectors here or
+        * there will occur accesses past EOD of the component
+        * data images thus erroring the raid set.
+        */
+       if (unlikely(bio_end_sector(bio) > mddev->array_sectors))
+               return DM_MAPIO_REQUEUE;
+
        mddev->pers->make_request(mddev, bio);
 
        return DM_MAPIO_SUBMITTED;
 }
 
+/* Return string describing the current sync action of @mddev */
 static const char *decipher_sync_action(struct mddev *mddev)
 {
        if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
@@ -1365,195 +3050,260 @@ static const char *decipher_sync_action(struct mddev *mddev)
        return "idle";
 }
 
-static void raid_status(struct dm_target *ti, status_type_t type,
-                       unsigned status_flags, char *result, unsigned maxlen)
+/*
+ * Return status string @rdev
+ *
+ * Status characters:
+ *
+ *  'D' = Dead/Failed device
+ *  'a' = Alive but not in-sync
+ *  'A' = Alive and in-sync
+ */
+static const char *__raid_dev_status(struct md_rdev *rdev, bool array_in_sync)
 {
-       struct raid_set *rs = ti->private;
-       unsigned raid_param_cnt = 1; /* at least 1 for chunksize */
-       unsigned sz = 0;
-       int i, array_in_sync = 0;
-       sector_t sync;
+       if (test_bit(Faulty, &rdev->flags))
+               return "D";
+       else if (!array_in_sync || !test_bit(In_sync, &rdev->flags))
+               return "a";
+       else
+               return "A";
+}
 
-       switch (type) {
-       case STATUSTYPE_INFO:
-               DMEMIT("%s %d ", rs->raid_type->name, rs->md.raid_disks);
+/* Helper to return resync/reshape progress for @rs and @array_in_sync */
+static sector_t rs_get_progress(struct raid_set *rs,
+                               sector_t resync_max_sectors, bool *array_in_sync)
+{
+       sector_t r, recovery_cp, curr_resync_completed;
+       struct mddev *mddev = &rs->md;
 
-               if (rs->raid_type->level) {
-                       if (test_bit(MD_RECOVERY_RUNNING, &rs->md.recovery))
-                               sync = rs->md.curr_resync_completed;
-                       else
-                               sync = rs->md.recovery_cp;
-
-                       if (sync >= rs->md.resync_max_sectors) {
-                               /*
-                                * Sync complete.
-                                */
-                               array_in_sync = 1;
-                               sync = rs->md.resync_max_sectors;
-                       } else if (test_bit(MD_RECOVERY_REQUESTED, &rs->md.recovery)) {
-                               /*
-                                * If "check" or "repair" is occurring, the array has
-                                * undergone and initial sync and the health characters
-                                * should not be 'a' anymore.
-                                */
-                               array_in_sync = 1;
+       curr_resync_completed = mddev->curr_resync_completed ?: mddev->recovery_cp;
+       recovery_cp = mddev->recovery_cp;
+       *array_in_sync = false;
+
+       if (rs_is_raid0(rs)) {
+               r = resync_max_sectors;
+               *array_in_sync = true;
+
+       } else {
+               r = mddev->reshape_position;
+
+               /* Reshape is relative to the array size */
+               if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) ||
+                   r != MaxSector) {
+                       if (r == MaxSector) {
+                               *array_in_sync = true;
+                               r = resync_max_sectors;
                        } else {
-                               /*
-                                * The array may be doing an initial sync, or it may
-                                * be rebuilding individual components.  If all the
-                                * devices are In_sync, then it is the array that is
-                                * being initialized.
-                                */
-                               for (i = 0; i < rs->md.raid_disks; i++)
-                                       if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
-                                               array_in_sync = 1;
+                               /* Got to reverse on backward reshape */
+                               if (mddev->reshape_backwards)
+                                       r = mddev->array_sectors - r;
+
+                               /* Devide by # of data stripes */
+                               sector_div(r, mddev_data_stripes(rs));
                        }
+
+               /* Sync is relative to the component device size */
+               } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+                       r = curr_resync_completed;
+               else
+                       r = recovery_cp;
+
+               if (r == MaxSector) {
+                       /*
+                        * Sync complete.
+                        */
+                       *array_in_sync = true;
+                       r = resync_max_sectors;
+               } else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+                       /*
+                        * If "check" or "repair" is occurring, the raid set has
+                        * undergone an initial sync and the health characters
+                        * should not be 'a' anymore.
+                        */
+                       *array_in_sync = true;
                } else {
-                       /* RAID0 */
-                       array_in_sync = 1;
-                       sync = rs->md.resync_max_sectors;
-               }
+                       struct md_rdev *rdev;
 
-               /*
-                * Status characters:
-                *  'D' = Dead/Failed device
-                *  'a' = Alive but not in-sync
-                *  'A' = Alive and in-sync
-                */
-               for (i = 0; i < rs->md.raid_disks; i++) {
-                       if (test_bit(Faulty, &rs->dev[i].rdev.flags))
-                               DMEMIT("D");
-                       else if (!array_in_sync ||
-                                !test_bit(In_sync, &rs->dev[i].rdev.flags))
-                               DMEMIT("a");
-                       else
-                               DMEMIT("A");
+                       /*
+                        * 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.
+                        */
+                       rdev_for_each(rdev, mddev)
+                               if (!test_bit(In_sync, &rdev->flags))
+                                       *array_in_sync = true;
+#if 0
+                       r = 0; /* HM FIXME: TESTME: https://bugzilla.redhat.com/show_bug.cgi?id=1210637 ? */
+#endif
                }
+       }
+
+       return r;
+}
+
+/* Helper to return @dev name or "-" if !@dev */
+static const char *__get_dev_name(struct dm_dev *dev)
+{
+       return dev ? dev->name : "-";
+}
+
+static void raid_status(struct dm_target *ti, status_type_t type,
+                       unsigned int status_flags, char *result, unsigned int maxlen)
+{
+       struct raid_set *rs = ti->private;
+       struct mddev *mddev = &rs->md;
+       struct r5conf *conf = mddev->private;
+       int i, max_nr_stripes = conf ? conf->max_nr_stripes : 0;
+       bool array_in_sync;
+       unsigned int raid_param_cnt = 1; /* at least 1 for chunksize */
+       unsigned int sz = 0;
+       unsigned int rebuild_disks;
+       unsigned int write_mostly_params = 0;
+       sector_t progress, resync_max_sectors, resync_mismatches;
+       const char *sync_action;
+       struct raid_type *rt;
+       struct md_rdev *rdev;
+
+       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;
+               progress = rs_get_progress(rs, resync_max_sectors, &array_in_sync);
+               resync_mismatches = (mddev->last_sync_action && !strcasecmp(mddev->last_sync_action, "check")) ?
+                                   atomic64_read(&mddev->resync_mismatches) : 0;
+               sync_action = decipher_sync_action(&rs->md);
+
+               /* HM FIXME: do we want another state char for raid0? It shows 'D' or 'A' now */
+               rdev_for_each(rdev, mddev)
+                       DMEMIT(__raid_dev_status(rdev, array_in_sync));
 
                /*
-                * In-sync ratio:
+                * In-sync/Reshape ratio:
                 *  The in-sync ratio shows the progress of:
-                *   - Initializing the array
-                *   - Rebuilding a subset of devices of the array
+                *   - 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) sync,
-                      (unsigned long long) rs->md.resync_max_sectors);
+               DMEMIT(" %llu/%llu", (unsigned long long) progress,
+                                    (unsigned long long) resync_max_sectors);
 
                /*
+                * v1.5.0+:
+                *
                 * Sync action:
-                *   See Documentation/device-mapper/dm-raid.c for
+                *   See Documentation/device-mapper/dm-raid.txt for
                 *   information on each of these states.
                 */
-               DMEMIT(" %s", decipher_sync_action(&rs->md));
+               DMEMIT(" %s", sync_action);
 
                /*
+                * v1.5.0+:
+                *
                 * resync_mismatches/mismatch_cnt
                 *   This field shows the number of discrepancies found when
-                *   performing a "check" of the array.
+                *   performing a "check" of the raid set.
                 */
-               DMEMIT(" %llu",
-                      (strcmp(rs->md.last_sync_action, "check")) ? 0 :
-                      (unsigned long long)
-                      atomic64_read(&rs->md.resync_mismatches));
-               break;
-       case STATUSTYPE_TABLE:
-               /* The string you would use to construct this array */
-               for (i = 0; i < rs->md.raid_disks; i++) {
-                       if ((rs->ctr_flags & CTR_FLAG_REBUILD) &&
-                           rs->dev[i].data_dev &&
-                           !test_bit(In_sync, &rs->dev[i].rdev.flags))
-                               raid_param_cnt += 2; /* for rebuilds */
-                       if (rs->dev[i].data_dev &&
-                           test_bit(WriteMostly, &rs->dev[i].rdev.flags))
-                               raid_param_cnt += 2;
-               }
-
-               raid_param_cnt += (hweight32(rs->ctr_flags & ~CTR_FLAG_REBUILD) * 2);
-               if (rs->ctr_flags & (CTR_FLAG_SYNC | CTR_FLAG_NOSYNC))
-                       raid_param_cnt--;
-
-               DMEMIT("%s %u %u", rs->raid_type->name,
-                      raid_param_cnt, rs->md.chunk_sectors);
-
-               if ((rs->ctr_flags & CTR_FLAG_SYNC) &&
-                   (rs->md.recovery_cp == MaxSector))
-                       DMEMIT(" sync");
-               if (rs->ctr_flags & CTR_FLAG_NOSYNC)
-                       DMEMIT(" nosync");
-
-               for (i = 0; i < rs->md.raid_disks; i++)
-                       if ((rs->ctr_flags & CTR_FLAG_REBUILD) &&
-                           rs->dev[i].data_dev &&
-                           !test_bit(In_sync, &rs->dev[i].rdev.flags))
-                               DMEMIT(" rebuild %u", i);
-
-               if (rs->ctr_flags & CTR_FLAG_DAEMON_SLEEP)
-                       DMEMIT(" daemon_sleep %lu",
-                              rs->md.bitmap_info.daemon_sleep);
-
-               if (rs->ctr_flags & CTR_FLAG_MIN_RECOVERY_RATE)
-                       DMEMIT(" min_recovery_rate %d", rs->md.sync_speed_min);
+               DMEMIT(" %llu", (unsigned long long) resync_mismatches);
 
-               if (rs->ctr_flags & CTR_FLAG_MAX_RECOVERY_RATE)
-                       DMEMIT(" max_recovery_rate %d", rs->md.sync_speed_max);
-
-               for (i = 0; i < rs->md.raid_disks; i++)
-                       if (rs->dev[i].data_dev &&
-                           test_bit(WriteMostly, &rs->dev[i].rdev.flags))
-                               DMEMIT(" write_mostly %u", i);
-
-               if (rs->ctr_flags & CTR_FLAG_MAX_WRITE_BEHIND)
-                       DMEMIT(" max_write_behind %lu",
-                              rs->md.bitmap_info.max_write_behind);
-
-               if (rs->ctr_flags & CTR_FLAG_STRIPE_CACHE) {
-                       struct r5conf *conf = rs->md.private;
-
-                       /* convert from kiB to sectors */
-                       DMEMIT(" stripe_cache %d",
-                              conf ? conf->max_nr_stripes * 2 : 0);
-               }
-
-               if (rs->ctr_flags & CTR_FLAG_REGION_SIZE)
-                       DMEMIT(" region_size %lu",
-                              rs->md.bitmap_info.chunksize >> 9);
-
-               if (rs->ctr_flags & CTR_FLAG_RAID10_COPIES)
-                       DMEMIT(" raid10_copies %u",
-                              raid10_md_layout_to_copies(rs->md.layout));
-
-               if (rs->ctr_flags & CTR_FLAG_RAID10_FORMAT)
-                       DMEMIT(" raid10_format %s",
-                              raid10_md_layout_to_format(rs->md.layout));
-
-               DMEMIT(" %d", rs->md.raid_disks);
-               for (i = 0; i < rs->md.raid_disks; i++) {
-                       if (rs->dev[i].meta_dev)
-                               DMEMIT(" %s", rs->dev[i].meta_dev->name);
-                       else
-                               DMEMIT(" -");
+               /*
+                * 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);
+               break;
 
-                       if (rs->dev[i].data_dev)
-                               DMEMIT(" %s", rs->dev[i].data_dev->name);
-                       else
-                               DMEMIT(" -");
-               }
+       case STATUSTYPE_TABLE:
+               /* Report the table line string you would use to construct this raid set */
+
+               /* Calculate raid parameter count */
+               for (i = 0; i < rs->raid_disks; i++)
+                       if (test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+                               write_mostly_params += 2;
+               rebuild_disks = memweight(rs->rebuild_disks, DISKS_ARRAY_ELEMS * sizeof(*rs->rebuild_disks));
+               raid_param_cnt += rebuild_disks * 2 +
+                                 write_mostly_params +
+                                 hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_NO_ARGS) +
+                                 hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_ONE_ARG) * 2;
+               /* Emit table line */
+               DMEMIT("%s %u %u", rs->raid_type->name, raid_param_cnt, mddev->new_chunk_sectors);
+               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_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_NOSYNC, &rs->ctr_flags))
+                       DMEMIT(" %s", dm_raid_arg_name_by_flag(CTR_FLAG_NOSYNC));
+               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_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_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_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_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_STRIPE_CACHE, &rs->ctr_flags))
+                       DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_STRIPE_CACHE),
+                                        max_nr_stripes);
+               if (rebuild_disks)
+                       for (i = 0; i < rs->raid_disks; i++)
+                               if (test_bit(rs->dev[i].rdev.raid_disk, (void *) rs->rebuild_disks))
+                                       DMEMIT(" %s %u", dm_raid_arg_name_by_flag(CTR_FLAG_REBUILD),
+                                                        rs->dev[i].rdev.raid_disk);
+               if (write_mostly_params)
+                       for (i = 0; i < rs->raid_disks; i++)
+                               if (test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+                                       DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_WRITE_MOSTLY),
+                                              rs->dev[i].rdev.raid_disk);
+               if (test_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags))
+                       DMEMIT(" %s %lu", dm_raid_arg_name_by_flag(CTR_FLAG_MAX_WRITE_BEHIND),
+                                         mddev->bitmap_info.max_write_behind);
+               if (test_bit(__CTR_FLAG_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_MIN_RECOVERY_RATE, &rs->ctr_flags))
+                       DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_MIN_RECOVERY_RATE),
+                                        mddev->sync_speed_min);
+               DMEMIT(" %d", rs->raid_disks);
+               for (i = 0; i < rs->raid_disks; i++)
+                       DMEMIT(" %s %s", __get_dev_name(rs->dev[i].meta_dev),
+                                        __get_dev_name(rs->dev[i].data_dev));
        }
 }
 
-static int raid_message(struct dm_target *ti, unsigned argc, char **argv)
+static int raid_message(struct dm_target *ti, unsigned int argc, char **argv)
 {
        struct raid_set *rs = ti->private;
        struct mddev *mddev = &rs->md;
 
-       if (!strcasecmp(argv[0], "reshape")) {
-               DMERR("Reshape not supported.");
-               return -EINVAL;
-       }
-
        if (!mddev->pers || !mddev->pers->sync_request)
                return -EINVAL;
 
@@ -1571,11 +3321,10 @@ static int raid_message(struct dm_target *ti, unsigned argc, char **argv)
                   test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
                return -EBUSY;
        else if (!strcasecmp(argv[0], "resync"))
-               set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-       else if (!strcasecmp(argv[0], "recover")) {
+               ; /* MD_RECOVERY_NEEDED set below */
+       else if (!strcasecmp(argv[0], "recover"))
                set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
-               set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-       } else {
+       else {
                if (!strcasecmp(argv[0], "check"))
                        set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
                else if (!!strcasecmp(argv[0], "repair"))
@@ -1588,11 +3337,11 @@ static int raid_message(struct dm_target *ti, unsigned argc, char **argv)
                 * canceling read-auto mode
                 */
                mddev->ro = 0;
-               if (!mddev->suspended)
+               if (!mddev->suspended && mddev->sync_thread)
                        md_wakeup_thread(mddev->sync_thread);
        }
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-       if (!mddev->suspended)
+       if (!mddev->suspended && mddev->thread)
                md_wakeup_thread(mddev->thread);
 
        return 0;
@@ -1602,28 +3351,27 @@ static int raid_iterate_devices(struct dm_target *ti,
                                iterate_devices_callout_fn fn, void *data)
 {
        struct raid_set *rs = ti->private;
-       unsigned i;
-       int ret = 0;
+       unsigned int i;
+       int r = 0;
 
-       for (i = 0; !ret && i < rs->md.raid_disks; i++)
+       for (i = 0; !r && i < rs->md.raid_disks; i++)
                if (rs->dev[i].data_dev)
-                       ret = fn(ti,
+                       r = fn(ti,
                                 rs->dev[i].data_dev,
                                 0, /* No offset on data devs */
                                 rs->md.dev_sectors,
                                 data);
 
-       return ret;
+       return r;
 }
 
 static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
        struct raid_set *rs = ti->private;
-       unsigned chunk_size = rs->md.chunk_sectors << 9;
-       struct r5conf *conf = rs->md.private;
+       unsigned int chunk_size = to_bytes(rs->md.chunk_sectors);
 
        blk_limits_io_min(limits, chunk_size);
-       blk_limits_io_opt(limits, chunk_size * (conf->raid_disks - conf->max_degraded));
+       blk_limits_io_opt(limits, chunk_size * mddev_data_stripes(rs));
 }
 
 static void raid_presuspend(struct dm_target *ti)
@@ -1637,7 +3385,11 @@ static void raid_postsuspend(struct dm_target *ti)
 {
        struct raid_set *rs = ti->private;
 
-       mddev_suspend(&rs->md);
+       if (test_and_clear_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags)) {
+               if (!rs->md.suspended)
+                       mddev_suspend(&rs->md);
+               rs->md.ro = 1;
+       }
 }
 
 static void attempt_restore_of_faulty_devices(struct raid_set *rs)
@@ -1651,7 +3403,8 @@ static void attempt_restore_of_faulty_devices(struct raid_set *rs)
        for (i = 0; i < rs->md.raid_disks; i++) {
                r = &rs->dev[i].rdev;
                if (test_bit(Faulty, &r->flags) && r->sb_page &&
-                   sync_page_io(r, 0, r->sb_size, r->sb_page, READ, 1)) {
+                   sync_page_io(r, 0, r->sb_size, r->sb_page,
+                                REQ_OP_READ, 0, true)) {
                        DMINFO("Faulty %s device #%d has readable super block."
                               "  Attempting to revive it.",
                               rs->raid_type->name, i);
@@ -1660,7 +3413,7 @@ static void attempt_restore_of_faulty_devices(struct raid_set *rs)
                         * 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
+                        * '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.
@@ -1696,34 +3449,192 @@ static void attempt_restore_of_faulty_devices(struct raid_set *rs)
        }
 }
 
-static void raid_resume(struct dm_target *ti)
+static int __load_dirty_region_bitmap(struct raid_set *rs)
 {
-       struct raid_set *rs = ti->private;
+       int r = 0;
+
+       /* Try loading the bitmap unless "raid0", which does not have one */
+       if (!rs_is_raid0(rs) &&
+           !test_and_set_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags)) {
+               r = bitmap_load(&rs->md);
+               if (r)
+                       DMERR("Failed to load bitmap");
+       }
 
-       if (rs->raid_type->level) {
-               set_bit(MD_CHANGE_DEVS, &rs->md.flags);
+       return r;
+}
 
-               if (!rs->bitmap_loaded) {
-                       bitmap_load(&rs->md);
-                       rs->bitmap_loaded = 1;
-               } else {
-                       /*
-                        * A secondary resume while the device is active.
-                        * Take this opportunity to check whether any failed
-                        * devices are reachable again.
-                        */
-                       attempt_restore_of_faulty_devices(rs);
+/* 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_CHANGE_DEVS, &mddev->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;
+
+       r = rs_setup_reshape(rs);
+       if (r)
+               return r;
+
+       /* Need to be resumed to be able to start reshape, recovery is frozen until raid_resume() though */
+       if (mddev->suspended)
+               mddev_resume(mddev);
+
+       /*
+        * 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;
                }
+       }
+
+       /* Suspend because a resume will happen in raid_resume() */
+       if (!mddev->suspended)
+               mddev_suspend(mddev);
+
+       /*
+        * Now reshape got set up, update superblocks to
+        * reflect the fact so that a table reload will
+        * access proper superblock content in the ctr.
+        */
+       rs_update_sbs(rs);
+
+       return 0;
+}
+
+static int raid_preresume(struct dm_target *ti)
+{
+       int r;
+       struct raid_set *rs = ti->private;
+       struct mddev *mddev = &rs->md;
+
+       /* This is a resume after a suspend of the set -> it's already started */
+       if (test_and_set_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags))
+               return 0;
+
+       /*
+        * The superblocks need to be updated on disk if the
+        * array is new or new devices got added (thus zeroed
+        * out by userspace) or __load_dirty_region_bitmap
+        * will overwrite them in core with old data or fail.
+        */
+       if (test_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags))
+               rs_update_sbs(rs);
+
+       /*
+        * Disable/enable discard support on raid set after any
+        * conversion, because devices can have been added
+        */
+       configure_discard_support(rs);
+
+       /* Load the bitmap from disk unless raid0 */
+       r = __load_dirty_region_bitmap(rs);
+       if (r)
+               return r;
+
+       /* Resize bitmap to adjust to changed region size (aka MD bitmap chunksize) */
+       if (test_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags) &&
+           mddev->bitmap_info.chunksize != to_bytes(rs->requested_bitmap_chunk_sectors)) {
+               r = bitmap_resize(mddev->bitmap, mddev->dev_sectors,
+                                 to_bytes(rs->requested_bitmap_chunk_sectors), 0);
+               if (r)
+                       DMERR("Failed to resize bitmap");
+       }
+
+       /* Check for any resize/reshape on @rs and adjust/initiate */
+       /* Be prepared for mddev_resume() in raid_resume() */
+       set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+       if (mddev->recovery_cp && mddev->recovery_cp < MaxSector) {
+               set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+               set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+               mddev->resync_min = mddev->recovery_cp;
+       }
 
-               clear_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
+       rs_set_capacity(rs);
+
+       /* Check for any reshape request unless new raid set */
+       if (test_and_clear_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
+               /* Initiate a reshape. */
+               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;
        }
 
-       mddev_resume(&rs->md);
+       return r;
+}
+
+static void raid_resume(struct dm_target *ti)
+{
+       struct raid_set *rs = ti->private;
+       struct mddev *mddev = &rs->md;
+
+       if (test_and_set_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags)) {
+               /*
+                * A secondary resume while the device is active.
+                * Take this opportunity to check whether any failed
+                * devices are reachable again.
+                */
+               attempt_restore_of_faulty_devices(rs);
+       } else {
+               mddev->ro = 0;
+               mddev->in_sync = 0;
+
+               /*
+                * When passing in flags to the ctr, we expect userspace
+                * to reset them because they made it to the superblocks
+                * and reload the mapping anyway.
+                *
+                * -> only unfreeze recovery in case of a table reload or
+                *    we'll have a bogus recovery/reshape position
+                *    retrieved from the superblock by the ctr because
+                *    the ongoing recovery/reshape will change it after read.
+                */
+               if (!test_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags))
+                       clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+
+               if (mddev->suspended)
+                       mddev_resume(mddev);
+       }
 }
 
 static struct target_type raid_target = {
        .name = "raid",
-       .version = {1, 8, 0},
+       .version = {1, 9, 0},
        .module = THIS_MODULE,
        .ctr = raid_ctr,
        .dtr = raid_dtr,
@@ -1734,6 +3645,7 @@ static struct target_type raid_target = {
        .io_hints = raid_io_hints,
        .presuspend = raid_presuspend,
        .postsuspend = raid_postsuspend,
+       .preresume = raid_preresume,
        .resume = raid_resume,
 };
 
@@ -1758,11 +3670,13 @@ module_param(devices_handle_discard_safely, bool, 0644);
 MODULE_PARM_DESC(devices_handle_discard_safely,
                 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
 
-MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target");
+MODULE_DESCRIPTION(DM_NAME " raid0/1/10/4/5/6 target");
+MODULE_ALIAS("dm-raid0");
 MODULE_ALIAS("dm-raid1");
 MODULE_ALIAS("dm-raid10");
 MODULE_ALIAS("dm-raid4");
 MODULE_ALIAS("dm-raid5");
 MODULE_ALIAS("dm-raid6");
 MODULE_AUTHOR("Neil Brown <dm-devel@redhat.com>");
+MODULE_AUTHOR("Heinz Mauelshagen <dm-devel@redhat.com>");
 MODULE_LICENSE("GPL");
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