dm raid: add reshaping support to the target (9dbd1aa3) · Commits · e / devices / android_kernel_teracube_2e

drivers/md/dm-raid.c

+447 −58

Original line number	Diff line number	Diff line
		@@ -189,6 +189,7 @@ struct raid_dev {
		#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

		/* Array elements of 64 bit needed for rebuild/write_mostly bits */
		#define DISKS_ARRAY_ELEMS ((MAX_RAID_DEVICES + (sizeof(uint64_t) * 8 - 1)) / sizeof(uint64_t) / 8)
		@@ -206,6 +207,7 @@ struct raid_set {
		struct dm_target *ti;

		uint32_t bitmap_loaded;
		uint32_t stripe_cache_entries;
		unsigned long ctr_flags;
		unsigned long runtime_flags;

		@@ -219,25 +221,22 @@ struct raid_set {
		struct mddev md;
		struct raid_type *raid_type;
		struct dm_target_callbacks callbacks;
		struct rs_layout rs_layout;

		struct raid_dev dev[0];
		};

		static void rs_config_backup(struct raid_set *rs)
		static void rs_config_backup(struct raid_set rs, struct rs_layout l)
		{
		struct mddev *mddev = &rs->md;
		struct rs_layout *l = &rs->rs_layout;

		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)
		static void rs_config_restore(struct raid_set rs, struct rs_layout l)
		{
		struct mddev *mddev = &rs->md;
		struct rs_layout *l = &rs->rs_layout;

		mddev->new_level = l->new_level;
		mddev->new_layout = l->new_layout;
		@@ -336,6 +335,12 @@ 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)
		{
		@@ -356,6 +361,20 @@ static bool rs_is_reshapable(struct raid_set *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)
		{
		smp_rmb();
		return rs->md.recovery_cp != MaxSector;
		}

		/* Return true, if raid set in @rs is reshaping */
		static bool rs_is_reshaping(struct raid_set *rs)
		{
		smp_rmb();
		return rs->md.reshape_position != MaxSector;
		}

		/*
		* bool helpers to test for various raid levels of a raid type
		*/
		@@ -590,6 +609,24 @@ static struct raid_type *get_raid_type_by_ll(const int level, const int layout)
		return NULL;
		}

		/*
		* 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;

		/* Make sure we access most actual mddev properties */
		smp_rmb();
		if (rs->ti->len != mddev->array_sectors && !rs_is_reshaping(rs)) {
		struct gendisk *gendisk = dm_disk(dm_table_get_md(rs->ti->table));

		set_capacity(gendisk, mddev->array_sectors);
		revalidate_disk(gendisk);
		}
		}

		/*
		* Set the mddev properties in @rs to the current
		* ones retrieved from the freshest superblock
		@@ -642,6 +679,7 @@ static struct raid_set raid_set_alloc(struct dm_target ti, struct raid_type *r

		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;
		@@ -874,7 +912,7 @@ 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 rebuilds_per_group = 0, copies;
		unsigned group_size, last_group_start;

		for (i = 0; i < rs->md.raid_disks; i++)
		@@ -894,7 +932,7 @@ 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;

		@@ -912,12 +950,11 @@ static int validate_raid_redundancy(struct raid_set *rs)
		* 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->raid_disks; i++) {
		if (!(i % copies))
		rebuilds_per_group = 0;
		d = i % rs->md.raid_disks;
		if ((!rs->dev[d].rdev.sb_page \|\|
		if ((!rs->dev[i].rdev.sb_page \|\|
		!test_bit(In_sync, &rs->dev[i].rdev.flags)) &&
		(++rebuilds_per_group >= copies))
		goto too_many;
		@@ -986,10 +1023,10 @@ static int validate_raid_redundancy(struct raid_set *rs)
		static int parse_raid_params(struct raid_set rs, struct dm_arg_set as,
		unsigned num_raid_params)
		{
		int raid10_format = ALGORITHM_RAID10_DEFAULT;
		int value, raid10_format = ALGORITHM_RAID10_DEFAULT;
		unsigned raid10_copies = 2;
		unsigned i;
		unsigned value, region_size = 0;
		unsigned region_size = 0;
		sector_t max_io_len;
		const char arg, key;
		struct raid_dev *rd;
		@@ -998,7 +1035,7 @@ static int parse_raid_params(struct raid_set rs, struct dm_arg_set as,
		arg = dm_shift_arg(as);
		num_raid_params--; /* Account for chunk_size argument */

		if (kstrtouint(arg, 10, &value) < 0) {
		if (kstrtoint(arg, 10, &value) < 0) {
		rs->ti->error = "Bad numerical argument given for chunk_size";
		return -EINVAL;
		}
		@@ -1105,7 +1142,7 @@ static int parse_raid_params(struct raid_set rs, struct dm_arg_set as,
		continue;
		}

		if (kstrtouint(arg, 10, &value) < 0) {
		if (kstrtoint(arg, 10, &value) < 0) {
		rs->ti->error = "Bad numerical argument given in raid params";
		return -EINVAL;
		}
		@@ -1207,21 +1244,12 @@ static int parse_raid_params(struct raid_set rs, struct dm_arg_set as,
		return -EINVAL;
		}

		/*
		* In device-mapper, we specify things in sectors, but
		* MD records this value in kB
		*/
		value /= 2;

		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";
		return -EINVAL;
		}

		rs->stripe_cache_entries = value;
		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MIN_RECOVERY_RATE))) {
		if (test_and_set_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags)) {
		rs->ti->error = "Only one min_recovery_rate argument pair allowed";
		@@ -1303,8 +1331,6 @@ static int parse_raid_params(struct raid_set rs, struct dm_arg_set as,
		rs->ti->error = "RAID10 format 'near' and 'raid10_use_near_sets' are incompatible";
		return -EINVAL;
		}

		rs->md.layout = rs->md.new_layout;
		}

		rs->raid10_copies = raid10_copies;
		@@ -1317,6 +1343,46 @@ static int parse_raid_params(struct raid_set rs, struct dm_arg_set as,
		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)
		{
		@@ -1337,6 +1403,7 @@ static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
		struct mddev *mddev = &rs->md;
		struct md_rdev *rdev;
		sector_t array_sectors = rs->ti->len, dev_sectors = rs->ti->len;
		sector_t cur_dev_sectors = rs->dev[0].rdev.sectors;

		if (use_mddev) {
		delta_disks = mddev->delta_disks;
		@@ -1377,6 +1444,9 @@ static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
		mddev->array_sectors = array_sectors;
		mddev->dev_sectors = dev_sectors;

		if (!rs_is_raid0(rs) && dev_sectors > cur_dev_sectors)
		mddev->recovery_cp = dev_sectors;

		return 0;
		bad:
		rs->ti->error = "Target length not divisible by number of data devices";
		@@ -1387,6 +1457,7 @@ static void do_table_event(struct work_struct *ws)
		{
		struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);

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

		@@ -1410,6 +1481,17 @@ static int rs_check_takeover(struct raid_set *rs)
		struct mddev *mddev = &rs->md;
		unsigned int near_copies;

		smp_rmb();
		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 */
		@@ -1419,7 +1501,7 @@ static int rs_check_takeover(struct raid_set *rs)

		/* raid0 -> raid10 */
		if (mddev->new_level == 10 &&
		!(rs->raid_disks % 2))
		!(rs->raid_disks % mddev->raid_disks))
		return 0;

		/* raid0 with multiple disks -> raid4/5/6 */
		@@ -1658,6 +1740,39 @@ struct dm_raid_superblock {
		/* 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;

		smp_rmb(); /* Make sure we access recent reshape position */

		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 (mddev->reshape_position && rs_is_reshaping(rs))
		rs->ti->error = "raid set already reshaping!";
		else if (!(rs_is_raid10(rs) \|\| rs_is_raid456(rs)))
		rs->ti->error = "Reshaping only supported for raid4/5/6/10";
		else
		return 0;

		return -EPERM;
		}

		static int read_disk_sb(struct md_rdev *rdev, int size)
		{
		BUG_ON(!rdev->sb_page);
		@@ -1936,6 +2051,10 @@ static int super_init_validation(struct raid_set rs, struct md_rdev rdev)
		* 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) {
		@@ -1961,9 +2080,9 @@ static int super_init_validation(struct raid_set rs, struct md_rdev rdev)
		if (new_devs == rs->raid_disks) {
		DMINFO("Superblocks created for new raid set");
		set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
		mddev->recovery_cp = 0;
		} else if (new_devs && new_devs != rs->raid_disks && !rebuilds) {
		} 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;
		@@ -1978,12 +2097,13 @@ static int super_init_validation(struct raid_set rs, struct md_rdev rdev)
		DMERR("new device%s provided without 'rebuild'",
		new_devs > 1 ? "s" : "");
		return -EINVAL;
		} else if (mddev->recovery_cp != MaxSector) {
		} 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 (mddev->reshape_position != MaxSector) {
		DMERR("'rebuild' specified while raid set is being reshaped");
		} 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;
		}
		}
		@@ -2082,7 +2202,7 @@ static int super_validate(struct raid_set rs, struct md_rdev rdev)
		* 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->md.reshape_position == MaxSector)
		else if (!rs_is_reshaping(rs))
		clear_bit(In_sync, &rdev->flags); /* Mandatory for recovery */
		}

		@@ -2181,15 +2301,13 @@ static int analyse_superblocks(struct dm_target ti, struct raid_set rs)
		* Validation of the freshest device provides the source of
		* validation for the remaining devices.
		*/
		if (super_validate(rs, freshest)) {
		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;
		}

		@@ -2343,6 +2461,106 @@ static int rs_setup_takeover(struct raid_set *rs)
		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 afreentioned out of place
		* reshaping based on userspace passing in
		* the "data_offset <sectors>" key/value
		* pair via te constructor
		*/

		/* Add disk(s) */
		if (rs->delta_disks > 0) {
		/* Prepare disks for check in raid4/5/6/10 {check\|start}_reshape */
		for (d = cur_raid_devs; d < rs->raid_disks; d++) {
		rdev = &rs->dev[d].rdev;
		clear_bit(In_sync, &rdev->flags);

		/*
		* save_raid_disk needs to be -1, or recovery_offset will be set to 0
		* by md, which'll store that erroneously in the superblock on reshape
		*/
		rdev->saved_raid_disk = -1;
		rdev->raid_disk = d;

		rdev->sectors = mddev->dev_sectors;
		rdev->recovery_offset = MaxSector;
		}

		mddev->reshape_backwards = 0; /* adding disks -> forward reshape */

		/* Remove disk(s) */
		} else if (rs->delta_disks < 0) {
		r = rs_set_dev_and_array_sectors(rs, true);
		mddev->reshape_backwards = 1; /* removing disk(s) -> backward reshape */

		/* Change layout and/or chunk size */
		} else {
		/*
		* Reshape layout (e.g. raid5_ls -> raid5_n) and/or chunk size:
		*
		* keeping number of disks and do layout change ->
		*
		* toggle reshape_backward depending on data_offset:
		*
		* - free space upfront -> reshape forward
		*
		* - free space at the end -> reshape backward
		*
		*
		* This utilizes free reshape space avoiding the need
		* for userspace to move (parts of) LV segments in
		* case of layout/chunksize change (for disk
		* adding/removing reshape space has to be at
		* the proper address (see above with delta_disks):
		*
		* add disk(s) -> begin
		* remove disk(s)-> end
		*/
		mddev->reshape_backwards = rs->dev[0].rdev.data_offset ? 0 : 1;
		}

		return r;
		}

		/*
		* Enable/disable discard support on RAID set depending on
		* RAID level and discard properties of underlying RAID members.
		@@ -2411,6 +2629,7 @@ static int raid_ctr(struct dm_target ti, unsigned argc, char *argv)
		unsigned num_raid_params, num_raid_devs;
		struct raid_set *rs = NULL;
		const char *arg;
		struct rs_layout rs_layout;
		struct dm_arg_set as = { argc, argv }, as_nrd;
		struct dm_arg _args[] = {
		{ 0, as.argc, "Cannot understand number of raid parameters" },
		@@ -2469,7 +2688,7 @@ static int raid_ctr(struct dm_target ti, unsigned argc, char *argv)
		* requested to be able to compare to superblock
		* members for conversion decisions.
		*/
		rs_config_backup(rs);
		rs_config_backup(rs, &rs_layout);

		r = analyse_superblocks(ti, rs);
		if (r)
		@@ -2480,13 +2699,23 @@ static int raid_ctr(struct dm_target ti, unsigned argc, char *argv)
		ti->num_flush_bios = 1;

		/* Restore any requested new layout for conversion decision */
		rs_config_restore(rs);
		rs_config_restore(rs, &rs_layout);

		if (test_bit(MD_ARRAY_FIRST_USE, &rs->md.flags)) {
		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
		rs_set_new(rs);
		} else if (rs_is_reshaping(rs))
		; /* skip rs setup */
		else if (rs_takeover_requested(rs)) {
		if (rs_is_reshaping(rs)) {
		ti->error = "Can't takeover a reshaping raid set";
		return -EPERM;
		}

		/*
		* If a takeover is needed, just set the level to
		* the new requested one and allow the raid set to run.
		*/
		if (rs_takeover_requested(rs)) {
		r = rs_check_takeover(rs);
		if (r)
		return r;
		@@ -2495,11 +2724,55 @@ static int raid_ctr(struct dm_target ti, unsigned argc, char *argv)
		if (r)
		return r;

		/* Tell preresume to update superblocks with new layout */
		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
		rs_set_new(rs);
		} else if (rs_reshape_requested(rs)) {
		rs_set_cur(rs); /* Dummy to reject, fill in */
		if (rs_is_reshaping(rs)) {
		ti->error = "raid set already reshaping!";
		return -EPERM;
		}

		if (rs_is_raid10(rs)) {
		if (rs->raid_disks != rs->md.raid_disks &&
		__is_raid10_near(rs->md.layout) &&
		rs->raid10_copies &&
		rs->raid10_copies != __raid10_near_copies(rs->md.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) {
		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);
		rs->md.layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
		rs->raid10_copies);
		rs->md.new_layout = rs->md.layout;

		} else
		set_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags);

		} else if (rs_is_raid456(rs))
		set_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags);

		/*
		* HM FIXME: process raid1 via delta_disks as well?
		* Would cause allocations in raid1->check_reshape
		* though, thus more issues with potential failures
		*/
		else if (rs_is_raid1(rs))
		rs->md.raid_disks = rs->raid_disks;

		if (rs->md.raid_disks < rs->raid_disks)
		set_bit(MD_ARRAY_FIRST_USE, &rs->md.flags);

		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
		rs_set_cur(rs);
		} else
		rs_set_cur(rs);

		@@ -2517,25 +2790,46 @@ static int raid_ctr(struct dm_target ti, unsigned argc, char *argv)
		mddev_lock_nointr(&rs->md);
		r = md_run(&rs->md);
		rs->md.in_sync = 0; /* Assume already marked dirty */
		mddev_unlock(&rs->md);

		if (r) {
		ti->error = "Fail to run raid array";
		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";
		r = -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)
		return r;

		/* Restore new, ctr requested layout to perform check */
		rs_config_restore(rs, &rs_layout);

		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:
		raid_set_free(rs);
		@@ -2557,6 +2851,17 @@ 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
		* 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;
		@@ -2709,7 +3014,7 @@ static void raid_status(struct dm_target *ti, status_type_t type,
		if (!rt)
		return;

		DMEMIT("%s %d ", rt ? rt->name : "unknown", mddev->raid_disks);
		DMEMIT("%s %d ", rt->name, mddev->raid_disks);

		/* Access most recent mddev properties for status output */
		smp_rmb();
		@@ -2718,7 +3023,7 @@ static void raid_status(struct dm_target *ti, status_type_t type,
		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")) ?
		(unsigned int) atomic64_read(&mddev->resync_mismatches) : 0;
		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 */
		@@ -2925,6 +3230,8 @@ static void raid_postsuspend(struct dm_target *ti)
		struct raid_set *rs = ti->private;

		mddev_suspend(&rs->md);
		rs->md.ro = 1;
		clear_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags);
		}

		static void attempt_restore_of_faulty_devices(struct raid_set *rs)
		@@ -2999,8 +3306,64 @@ static int __load_dirty_region_bitmap(struct raid_set *rs)
		return r;
		}

		/*
		* 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);

		mddev->ro = 0;
		md_update_sb(mddev, 1);
		mddev->ro = 1;

		return 0;
		}

		static int raid_preresume(struct dm_target *ti)
		{
		int r;
		struct raid_set *rs = ti->private;
		struct mddev *mddev = &rs->md;

		@@ -3034,7 +3397,33 @@ static int raid_preresume(struct dm_target *ti)
		configure_discard_support(rs);

		/* Load the bitmap from disk unless raid0 */
		return __load_dirty_region_bitmap(rs);
		r = __load_dirty_region_bitmap(rs);
		if (r)
		return r;

		/* 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;
		}

		rs_set_capacity(rs);

		/* Check for any reshape request and region size change 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;
		}

		return r;
		}

		static void raid_resume(struct dm_target *ti)