Merge tag 'for-5.8/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - The largest change for this cycle is the DM zoned target's metadata
   version 2 feature that adds support for pairing regular block devices
   with a zoned device to ease the performance impact associated with
   finite random zones of zoned device.

   The changes came in three batches: the first prepared for and then
   added the ability to pair a single regular block device, the second
   was a batch of fixes to improve zoned's reclaim heuristic, and the
   third removed the limitation of only adding a single additional
   regular block device to allow many devices.

   Testing has shown linear scaling as more devices are added.

 - Add new emulated block size (ebs) target that emulates a smaller
   logical_block_size than a block device supports

   The primary use-case is to emulate "512e" devices that have 512 byte
   logical_block_size and 4KB physical_block_size. This is useful to
   some legacy applications that otherwise wouldn't be able to be used
   on 4K devices because they depend on issuing IO in 512 byte
   granularity.

 - Add discard interfaces to DM bufio. First consumer of the interface
   is the dm-ebs target that makes heavy use of dm-bufio.

 - Fix DM crypt's block queue_limits stacking to not truncate
   logic_block_size.

 - Add Documentation for DM integrity's status line.

 - Switch DMDEBUG from a compile time config option to instead use
   dynamic debug via pr_debug.

 - Fix DM multipath target's hueristic for how it manages
   "queue_if_no_path" state internally.

   DM multipath now avoids disabling "queue_if_no_path" unless it is
   actually needed (e.g. in response to configure timeout or explicit
   "fail_if_no_path" message).

   This fixes reports of spurious -EIO being reported back to userspace
   application during fault tolerance testing with an NVMe backend.
   Added various dynamic DMDEBUG messages to assist with debugging
   queue_if_no_path in the future.

 - Add a new DM multipath "Historical Service Time" Path Selector.

 - Fix DM multipath's dm_blk_ioctl() to switch paths on IO error.

 - Improve DM writecache target performance by using explicit cache
   flushing for target's single-threaded usecase and a small cleanup to
   remove unnecessary test in persistent_memory_claim.

 - Other small cleanups in DM core, dm-persistent-data, and DM
   integrity.

* tag 'for-5.8/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (62 commits)
  dm crypt: avoid truncating the logical block size
  dm mpath: add DM device name to Failing/Reinstating path log messages
  dm mpath: enhance queue_if_no_path debugging
  dm mpath: restrict queue_if_no_path state machine
  dm mpath: simplify __must_push_back
  dm zoned: check superblock location
  dm zoned: prefer full zones for reclaim
  dm zoned: select reclaim zone based on device index
  dm zoned: allocate zone by device index
  dm zoned: support arbitrary number of devices
  dm zoned: move random and sequential zones into struct dmz_dev
  dm zoned: per-device reclaim
  dm zoned: add metadata pointer to struct dmz_dev
  dm zoned: add device pointer to struct dm_zone
  dm zoned: allocate temporary superblock for tertiary devices
  dm zoned: convert to xarray
  dm zoned: add a 'reserved' zone flag
  dm zoned: improve logging messages for reclaim
  dm zoned: avoid unnecessary device recalulation for secondary superblock
  dm zoned: add debugging message for reading superblocks
  ...

25 files changed, 2650 insertions, 636 deletions

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index d6d5ab23c088..6665b56865b7 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -269,6 +269,7 @@ config DM_UNSTRIPED
 config DM_CRYPT
 	tristate "Crypt target support"
 	depends on BLK_DEV_DM
+	depends on (ENCRYPTED_KEYS || ENCRYPTED_KEYS=n)
 	select CRYPTO
 	select CRYPTO_CBC
 	select CRYPTO_ESSIV
@@ -336,6 +337,14 @@ config DM_WRITECACHE
 	   The writecache target doesn't cache reads because reads are supposed
 	   to be cached in standard RAM.
 
+config DM_EBS
+	tristate "Emulated block size target (EXPERIMENTAL)"
+	depends on BLK_DEV_DM
+	select DM_BUFIO
+	help
+	  dm-ebs emulates smaller logical block size on backing devices
+	  with larger ones (e.g. 512 byte sectors on 4K native disks).
+
 config DM_ERA
        tristate "Era target (EXPERIMENTAL)"
        depends on BLK_DEV_DM
@@ -443,6 +452,17 @@ config DM_MULTIPATH_ST
 
 	  If unsure, say N.
 
+config DM_MULTIPATH_HST
+	tristate "I/O Path Selector based on historical service time"
+	depends on DM_MULTIPATH
+	help
+	  This path selector is a dynamic load balancer which selects
+	  the path expected to complete the incoming I/O in the shortest
+	  time by comparing estimated service time (based on historical
+	  service time).
+
+	  If unsure, say N.
+
 config DM_DELAY
 	tristate "I/O delaying target"
 	depends on BLK_DEV_DM
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index d91a7edcd2ab..31840f95cd40 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -17,6 +17,7 @@ dm-thin-pool-y	+= dm-thin.o dm-thin-metadata.o
 dm-cache-y	+= dm-cache-target.o dm-cache-metadata.o dm-cache-policy.o \
 		    dm-cache-background-tracker.o
 dm-cache-smq-y   += dm-cache-policy-smq.o
+dm-ebs-y	+= dm-ebs-target.o
 dm-era-y	+= dm-era-target.o
 dm-clone-y	+= dm-clone-target.o dm-clone-metadata.o
 dm-verity-y	+= dm-verity-target.o
@@ -54,6 +55,7 @@ obj-$(CONFIG_DM_FLAKEY)		+= dm-flakey.o
 obj-$(CONFIG_DM_MULTIPATH)	+= dm-multipath.o dm-round-robin.o
 obj-$(CONFIG_DM_MULTIPATH_QL)	+= dm-queue-length.o
 obj-$(CONFIG_DM_MULTIPATH_ST)	+= dm-service-time.o
+obj-$(CONFIG_DM_MULTIPATH_HST)	+= dm-historical-service-time.o
 obj-$(CONFIG_DM_SWITCH)		+= dm-switch.o
 obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o
 obj-$(CONFIG_DM_PERSISTENT_DATA)	+= persistent-data/
@@ -65,6 +67,7 @@ obj-$(CONFIG_DM_THIN_PROVISIONING)	+= dm-thin-pool.o
 obj-$(CONFIG_DM_VERITY)		+= dm-verity.o
 obj-$(CONFIG_DM_CACHE)		+= dm-cache.o
 obj-$(CONFIG_DM_CACHE_SMQ)	+= dm-cache-smq.o
+obj-$(CONFIG_DM_EBS)		+= dm-ebs.o
 obj-$(CONFIG_DM_ERA)		+= dm-era.o
 obj-$(CONFIG_DM_CLONE)		+= dm-clone.o
 obj-$(CONFIG_DM_LOG_WRITES)	+= dm-log-writes.o
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index d1786cfd7f22..6d1565021d74 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -256,12 +256,35 @@ static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
 		if (b->block == block)
 			return b;
 
-		n = (b->block < block) ? n->rb_left : n->rb_right;
+		n = block < b->block ? n->rb_left : n->rb_right;
 	}
 
 	return NULL;
 }
 
+static struct dm_buffer *__find_next(struct dm_bufio_client *c, sector_t block)
+{
+	struct rb_node *n = c->buffer_tree.rb_node;
+	struct dm_buffer *b;
+	struct dm_buffer *best = NULL;
+
+	while (n) {
+		b = container_of(n, struct dm_buffer, node);
+
+		if (b->block == block)
+			return b;
+
+		if (block <= b->block) {
+			n = n->rb_left;
+			best = b;
+		} else {
+			n = n->rb_right;
+		}
+	}
+
+	return best;
+}
+
 static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
 {
 	struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL;
@@ -276,8 +299,8 @@ static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
 		}
 
 		parent = *new;
-		new = (found->block < b->block) ?
-			&((*new)->rb_left) : &((*new)->rb_right);
+		new = b->block < found->block ?
+			&found->node.rb_left : &found->node.rb_right;
 	}
 
 	rb_link_node(&b->node, parent, new);
@@ -631,6 +654,19 @@ dmio:
 	submit_bio(bio);
 }
 
+static inline sector_t block_to_sector(struct dm_bufio_client *c, sector_t block)
+{
+	sector_t sector;
+
+	if (likely(c->sectors_per_block_bits >= 0))
+		sector = block << c->sectors_per_block_bits;
+	else
+		sector = block * (c->block_size >> SECTOR_SHIFT);
+	sector += c->start;
+
+	return sector;
+}
+
 static void submit_io(struct dm_buffer *b, int rw, void (*end_io)(struct dm_buffer *, blk_status_t))
 {
 	unsigned n_sectors;
@@ -639,11 +675,7 @@ static void submit_io(struct dm_buffer *b, int rw, void (*end_io)(struct dm_buff
 
 	b->end_io = end_io;
 
-	if (likely(b->c->sectors_per_block_bits >= 0))
-		sector = b->block << b->c->sectors_per_block_bits;
-	else
-		sector = b->block * (b->c->block_size >> SECTOR_SHIFT);
-	sector += b->c->start;
+	sector = block_to_sector(b->c, b->block);
 
 	if (rw != REQ_OP_WRITE) {
 		n_sectors = b->c->block_size >> SECTOR_SHIFT;
@@ -1326,6 +1358,30 @@ int dm_bufio_issue_flush(struct dm_bufio_client *c)
 EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
 
 /*
+ * Use dm-io to send a discard request to flush the device.
+ */
+int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count)
+{
+	struct dm_io_request io_req = {
+		.bi_op = REQ_OP_DISCARD,
+		.bi_op_flags = REQ_SYNC,
+		.mem.type = DM_IO_KMEM,
+		.mem.ptr.addr = NULL,
+		.client = c->dm_io,
+	};
+	struct dm_io_region io_reg = {
+		.bdev = c->bdev,
+		.sector = block_to_sector(c, block),
+		.count = block_to_sector(c, count),
+	};
+
+	BUG_ON(dm_bufio_in_request());
+
+	return dm_io(&io_req, 1, &io_reg, NULL);
+}
+EXPORT_SYMBOL_GPL(dm_bufio_issue_discard);
+
+/*
  * We first delete any other buffer that may be at that new location.
  *
  * Then, we write the buffer to the original location if it was dirty.
@@ -1401,6 +1457,14 @@ retry:
 }
 EXPORT_SYMBOL_GPL(dm_bufio_release_move);
 
+static void forget_buffer_locked(struct dm_buffer *b)
+{
+	if (likely(!b->hold_count) && likely(!b->state)) {
+		__unlink_buffer(b);
+		__free_buffer_wake(b);
+	}
+}
+
 /*
  * Free the given buffer.
  *
@@ -1414,15 +1478,36 @@ void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
 	dm_bufio_lock(c);
 
 	b = __find(c, block);
-	if (b && likely(!b->hold_count) && likely(!b->state)) {
-		__unlink_buffer(b);
-		__free_buffer_wake(b);
-	}
+	if (b)
+		forget_buffer_locked(b);
 
 	dm_bufio_unlock(c);
 }
 EXPORT_SYMBOL_GPL(dm_bufio_forget);
 
+void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks)
+{
+	struct dm_buffer *b;
+	sector_t end_block = block + n_blocks;
+
+	while (block < end_block) {
+		dm_bufio_lock(c);
+
+		b = __find_next(c, block);
+		if (b) {
+			block = b->block + 1;
+			forget_buffer_locked(b);
+		}
+
+		dm_bufio_unlock(c);
+
+		if (!b)
+			break;
+	}
+
+}
+EXPORT_SYMBOL_GPL(dm_bufio_forget_buffers);
+
 void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
 {
 	c->minimum_buffers = n;
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 3df90daba89e..000ddfab5ba0 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -34,7 +34,9 @@
 #include <crypto/aead.h>
 #include <crypto/authenc.h>
 #include <linux/rtnetlink.h> /* for struct rtattr and RTA macros only */
+#include <linux/key-type.h>
 #include <keys/user-type.h>
+#include <keys/encrypted-type.h>
 
 #include <linux/device-mapper.h>
 
@@ -212,7 +214,7 @@ struct crypt_config {
 	struct mutex bio_alloc_lock;
 
 	u8 *authenc_key; /* space for keys in authenc() format (if used) */
-	u8 key[0];
+	u8 key[];
 };
 
 #define MIN_IOS		64
@@ -2215,12 +2217,47 @@ static bool contains_whitespace(const char *str)
 	return false;
 }
 
+static int set_key_user(struct crypt_config *cc, struct key *key)
+{
+	const struct user_key_payload *ukp;
+
+	ukp = user_key_payload_locked(key);
+	if (!ukp)
+		return -EKEYREVOKED;
+
+	if (cc->key_size != ukp->datalen)
+		return -EINVAL;
+
+	memcpy(cc->key, ukp->data, cc->key_size);
+
+	return 0;
+}
+
+#if defined(CONFIG_ENCRYPTED_KEYS) || defined(CONFIG_ENCRYPTED_KEYS_MODULE)
+static int set_key_encrypted(struct crypt_config *cc, struct key *key)
+{
+	const struct encrypted_key_payload *ekp;
+
+	ekp = key->payload.data[0];
+	if (!ekp)
+		return -EKEYREVOKED;
+
+	if (cc->key_size != ekp->decrypted_datalen)
+		return -EINVAL;
+
+	memcpy(cc->key, ekp->decrypted_data, cc->key_size);
+
+	return 0;
+}
+#endif /* CONFIG_ENCRYPTED_KEYS */
+
 static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string)
 {
 	char *new_key_string, *key_desc;
 	int ret;
+	struct key_type *type;
 	struct key *key;
-	const struct user_key_payload *ukp;
+	int (*set_key)(struct crypt_config *cc, struct key *key);
 
 	/*
 	 * Reject key_string with whitespace. dm core currently lacks code for
@@ -2236,16 +2273,26 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
 	if (!key_desc || key_desc == key_string || !strlen(key_desc + 1))
 		return -EINVAL;
 
-	if (strncmp(key_string, "logon:", key_desc - key_string + 1) &&
-	    strncmp(key_string, "user:", key_desc - key_string + 1))
+	if (!strncmp(key_string, "logon:", key_desc - key_string + 1)) {
+		type = &key_type_logon;
+		set_key = set_key_user;
+	} else if (!strncmp(key_string, "user:", key_desc - key_string + 1)) {
+		type = &key_type_user;
+		set_key = set_key_user;
+#if defined(CONFIG_ENCRYPTED_KEYS) || defined(CONFIG_ENCRYPTED_KEYS_MODULE)
+	} else if (!strncmp(key_string, "encrypted:", key_desc - key_string + 1)) {
+		type = &key_type_encrypted;
+		set_key = set_key_encrypted;
+#endif
+	} else {
 		return -EINVAL;
+	}
 
 	new_key_string = kstrdup(key_string, GFP_KERNEL);
 	if (!new_key_string)
 		return -ENOMEM;
 
-	key = request_key(key_string[0] == 'l' ? &key_type_logon : &key_type_user,
-			  key_desc + 1, NULL);
+	key = request_key(type, key_desc + 1, NULL);
 	if (IS_ERR(key)) {
 		kzfree(new_key_string);
 		return PTR_ERR(key);
@@ -2253,23 +2300,14 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
 
 	down_read(&key->sem);
 
-	ukp = user_key_payload_locked(key);
-	if (!ukp) {
-		up_read(&key->sem);
-		key_put(key);
-		kzfree(new_key_string);
-		return -EKEYREVOKED;
-	}
-
-	if (cc->key_size != ukp->datalen) {
+	ret = set_key(cc, key);
+	if (ret < 0) {
 		up_read(&key->sem);
 		key_put(key);
 		kzfree(new_key_string);
-		return -EINVAL;
+		return ret;
 	}
 
-	memcpy(cc->key, ukp->data, cc->key_size);
-
 	up_read(&key->sem);
 	key_put(key);
 
@@ -2323,7 +2361,7 @@ static int get_key_size(char **key_string)
 	return (*key_string[0] == ':') ? -EINVAL : strlen(*key_string) >> 1;
 }
 
-#endif
+#endif /* CONFIG_KEYS */
 
 static int crypt_set_key(struct crypt_config *cc, char *key)
 {
@@ -3274,7 +3312,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits)
 	limits->max_segment_size = PAGE_SIZE;
 
 	limits->logical_block_size =
-		max_t(unsigned short, limits->logical_block_size, cc->sector_size);
+		max_t(unsigned, limits->logical_block_size, cc->sector_size);
 	limits->physical_block_size =
 		max_t(unsigned, limits->physical_block_size, cc->sector_size);
 	limits->io_min = max_t(unsigned, limits->io_min, cc->sector_size);
@@ -3282,7 +3320,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 static struct target_type crypt_target = {
 	.name   = "crypt",
-	.version = {1, 20, 0},
+	.version = {1, 21, 0},
 	.module = THIS_MODULE,
 	.ctr    = crypt_ctr,
 	.dtr    = crypt_dtr,
diff --git a/drivers/md/dm-ebs-target.c b/drivers/md/dm-ebs-target.c
new file mode 100644
index 000000000000..44451276f128
--- /dev/null
+++ b/drivers/md/dm-ebs-target.c
@@ -0,0 +1,471 @@
+/*
+ * Copyright (C) 2020 Red Hat GmbH
+ *
+ * This file is released under the GPL.
+ *
+ * Device-mapper target to emulate smaller logical block
+ * size on backing devices exposing (natively) larger ones.
+ *
+ * E.g. 512 byte sector emulation on 4K native disks.
+ */
+
+#include "dm.h"
+#include <linux/module.h>
+#include <linux/workqueue.h>
+#include <linux/dm-bufio.h>
+
+#define DM_MSG_PREFIX "ebs"
+
+static void ebs_dtr(struct dm_target *ti);
+
+/* Emulated block size context. */
+struct ebs_c {
+	struct dm_dev *dev;		/* Underlying device to emulate block size on. */
+	struct dm_bufio_client *bufio;	/* Use dm-bufio for read and read-modify-write processing. */
+	struct workqueue_struct *wq;	/* Workqueue for ^ processing of bios. */
+	struct work_struct ws;		/* Work item used for ^. */
+	struct bio_list bios_in;	/* Worker bios input list. */
+	spinlock_t lock;		/* Guard bios input list above. */
+	sector_t start;			/* <start> table line argument, see ebs_ctr below. */
+	unsigned int e_bs;		/* Emulated block size in sectors exposed to upper layer. */
+	unsigned int u_bs;		/* Underlying block size in sectors retrievd from/set on lower layer device. */
+	unsigned char block_shift;	/* bitshift sectors -> blocks used in dm-bufio API. */
+	bool u_bs_set:1;		/* Flag to indicate underlying block size is set on table line. */
+};
+
+static inline sector_t __sector_to_block(struct ebs_c *ec, sector_t sector)
+{
+	return sector >> ec->block_shift;
+}
+
+static inline sector_t __block_mod(sector_t sector, unsigned int bs)
+{
+	return sector & (bs - 1);
+}
+
+/* Return number of blocks for a bio, accounting for misalignement of start and end sectors. */
+static inline unsigned int __nr_blocks(struct ebs_c *ec, struct bio *bio)
+{
+	sector_t end_sector = __block_mod(bio->bi_iter.bi_sector, ec->u_bs) + bio_sectors(bio);
+
+	return __sector_to_block(ec, end_sector) + (__block_mod(end_sector, ec->u_bs) ? 1 : 0);
+}
+
+static inline bool __ebs_check_bs(unsigned int bs)
+{
+	return bs && is_power_of_2(bs);
+}
+
+/*
+ * READ/WRITE:
+ *
+ * copy blocks between bufio blocks and bio vector's (partial/overlapping) pages.
+ */
+static int __ebs_rw_bvec(struct ebs_c *ec, int rw, struct bio_vec *bv, struct bvec_iter *iter)
+{
+	int r = 0;
+	unsigned char *ba, *pa;
+	unsigned int cur_len;
+	unsigned int bv_len = bv->bv_len;
+	unsigned int buf_off = to_bytes(__block_mod(iter->bi_sector, ec->u_bs));
+	sector_t block = __sector_to_block(ec, iter->bi_sector);
+	struct dm_buffer *b;
+
+	if (unlikely(!bv->bv_page || !bv_len))
+		return -EIO;
+
+	pa = page_address(bv->bv_page) + bv->bv_offset;
+
+	/* Handle overlapping page <-> blocks */
+	while (bv_len) {
+		cur_len = min(dm_bufio_get_block_size(ec->bufio) - buf_off, bv_len);
+
+		/* Avoid reading for writes in case bio vector's page overwrites block completely. */
+		if (rw == READ || buf_off || bv_len < dm_bufio_get_block_size(ec->bufio))
+			ba = dm_bufio_read(ec->bufio, block, &b);
+		else
+			ba = dm_bufio_new(ec->bufio, block, &b);
+
+		if (unlikely(IS_ERR(ba))) {
+			/*
+			 * Carry on with next buffer, if any, to issue all possible
+			 * data but return error.
+			 */
+			r = PTR_ERR(ba);
+		} else {
+			/* Copy data to/from bio to buffer if read/new was successful above. */
+			ba += buf_off;
+			if (rw == READ) {
+				memcpy(pa, ba, cur_len);
+				flush_dcache_page(bv->bv_page);
+			} else {
+				flush_dcache_page(bv->bv_page);
+				memcpy(ba, pa, cur_len);
+				dm_bufio_mark_partial_buffer_dirty(b, buf_off, buf_off + cur_len);
+			}
+
+			dm_bufio_release(b);
+		}
+
+		pa += cur_len;
+		bv_len -= cur_len;
+		buf_off = 0;
+		block++;
+	}
+
+	return r;
+}
+
+/* READ/WRITE: iterate bio vector's copying between (partial) pages and bufio blocks. */
+static int __ebs_rw_bio(struct ebs_c *ec, int rw, struct bio *bio)
+{
+	int r = 0, rr;
+	struct bio_vec bv;
+	struct bvec_iter iter;
+
+	bio_for_each_bvec(bv, bio, iter) {
+		rr = __ebs_rw_bvec(ec, rw, &bv, &iter);
+		if (rr)
+			r = rr;
+	}
+
+	return r;
+}
+
+/*
+ * Discard bio's blocks, i.e. pass discards down.
+ *
+ * Avoid discarding partial blocks at beginning and end;
+ * return 0 in case no blocks can be discarded as a result.
+ */
+static int __ebs_discard_bio(struct ebs_c *ec, struct bio *bio)
+{
+	sector_t block, blocks, sector = bio->bi_iter.bi_sector;
+
+	block = __sector_to_block(ec, sector);
+	blocks = __nr_blocks(ec, bio);
+
+	/*
+	 * Partial first underlying block (__nr_blocks() may have
+	 * resulted in one block).
+	 */
+	if (__block_mod(sector, ec->u_bs)) {
+		block++;
+		blocks--;
+	}
+
+	/* Partial last underlying block if any. */
+	if (blocks && __block_mod(bio_end_sector(bio), ec->u_bs))
+		blocks--;
+
+	return blocks ? dm_bufio_issue_discard(ec->bufio, block, blocks) : 0;
+}
+
+/* Release blocks them from the bufio cache. */
+static void __ebs_forget_bio(struct ebs_c *ec, struct bio *bio)
+{
+	sector_t blocks, sector = bio->bi_iter.bi_sector;
+
+	blocks = __nr_blocks(ec, bio);
+
+	dm_bufio_forget_buffers(ec->bufio, __sector_to_block(ec, sector), blocks);
+}
+
+/* Worker funtion to process incoming bios. */
+static void __ebs_process_bios(struct work_struct *ws)
+{
+	int r;
+	bool write = false;
+	sector_t block1, block2;
+	struct ebs_c *ec = container_of(ws, struct ebs_c, ws);
+	struct bio *bio;
+	struct bio_list bios;
+
+	bio_list_init(&bios);
+
+	spin_lock_irq(&ec->lock);
+	bios = ec->bios_in;
+	bio_list_init(&ec->bios_in);
+	spin_unlock_irq(&ec->lock);
+
+	/* Prefetch all read and any mis-aligned write buffers */
+	bio_list_for_each(bio, &bios) {
+		block1 = __sector_to_block(ec, bio->bi_iter.bi_sector);
+		if (bio_op(bio) == REQ_OP_READ)
+			dm_bufio_prefetch(ec->bufio, block1, __nr_blocks(ec, bio));
+		else if (bio_op(bio) == REQ_OP_WRITE && !(bio->bi_opf & REQ_PREFLUSH)) {
+			block2 = __sector_to_block(ec, bio_end_sector(bio));
+			if (__block_mod(bio->bi_iter.bi_sector, ec->u_bs))
+				dm_bufio_prefetch(ec->bufio, block1, 1);
+			if (__block_mod(bio_end_sector(bio), ec->u_bs) && block2 != block1)
+				dm_bufio_prefetch(ec->bufio, block2, 1);
+		}
+	}
+
+	bio_list_for_each(bio, &bios) {
+		r = -EIO;
+		if (bio_op(bio) == REQ_OP_READ)
+			r = __ebs_rw_bio(ec, READ, bio);
+		else if (bio_op(bio) == REQ_OP_WRITE) {
+			write = true;
+			r = __ebs_rw_bio(ec, WRITE, bio);
+		} else if (bio_op(bio) == REQ_OP_DISCARD) {
+			__ebs_forget_bio(ec, bio);
+			r = __ebs_discard_bio(ec, bio);
+		}
+
+		if (r < 0)
+			bio->bi_status = errno_to_blk_status(r);
+	}
+
+	/*
+	 * We write dirty buffers after processing I/O on them
+	 * but before we endio thus addressing REQ_FUA/REQ_SYNC.
+	 */
+	r = write ? dm_bufio_write_dirty_buffers(ec->bufio) : 0;
+
+	while ((bio = bio_list_pop(&bios))) {
+		/* Any other request is endioed. */
+		if (unlikely(r && bio_op(bio) == REQ_OP_WRITE))
+			bio_io_error(bio);
+		else
+			bio_endio(bio);
+	}
+}
+
+/*
+ * Construct an emulated block size mapping: <dev_path> <offset> <ebs> [<ubs>]
+ *
+ * <dev_path>: path of the underlying device
+ * <offset>: offset in 512 bytes sectors into <dev_path>
+ * <ebs>: emulated block size in units of 512 bytes exposed to the upper layer
+ * [<ubs>]: underlying block size in units of 512 bytes imposed on the lower layer;
+ * 	    optional, if not supplied, retrieve logical block size from underlying device
+ */
+static int ebs_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+	int r;
+	unsigned short tmp1;
+	unsigned long long tmp;
+	char dummy;
+	struct ebs_c *ec;
+
+	if (argc < 3 || argc > 4) {
+		ti->error = "Invalid argument count";
+		return -EINVAL;
+	}
+
+	ec = ti->private = kzalloc(sizeof(*ec), GFP_KERNEL);
+	if (!ec) {
+		ti->error = "Cannot allocate ebs context";
+		return -ENOMEM;
+	}
+
+	r = -EINVAL;
+	if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 ||
+	    tmp != (sector_t)tmp ||
+	    (sector_t)tmp >= ti->len) {
+		ti->error = "Invalid device offset sector";
+		goto bad;
+	}
+	ec->start = tmp;
+
+	if (sscanf(argv[2], "%hu%c", &tmp1, &dummy) != 1 ||
+	    !__ebs_check_bs(tmp1) ||
+	    to_bytes(tmp1) > PAGE_SIZE) {
+		ti->error = "Invalid emulated block size";
+		goto bad;
+	}
+	ec->e_bs = tmp1;
+
+	if (argc > 3) {
+		if (sscanf(argv[3], "%hu%c", &tmp1, &dummy) != 1 || !__ebs_check_bs(tmp1)) {
+			ti->error = "Invalid underlying block size";
+			goto bad;
+		}
+		ec->u_bs = tmp1;
+		ec->u_bs_set = true;
+	} else
+		ec->u_bs_set = false;
+
+	r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &ec->dev);
+	if (r) {
+		ti->error = "Device lookup failed";
+		ec->dev = NULL;
+		goto bad;
+	}
+
+	r = -EINVAL;
+	if (!ec->u_bs_set) {
+		ec->u_bs = to_sector(bdev_logical_block_size(ec->dev->bdev));
+		if (!__ebs_check_bs(ec->u_bs)) {
+			ti->error = "Invalid retrieved underlying block size";
+			goto bad;
+		}
+	}
+
+	if (!ec->u_bs_set && ec->e_bs == ec->u_bs)
+		DMINFO("Emulation superfluous: emulated equal to underlying block size");
+
+	if (__block_mod(ec->start, ec->u_bs)) {
+		ti->error = "Device offset must be multiple of underlying block size";
+		goto bad;
+	}
+
+	ec->bufio = dm_bufio_client_create(ec->dev->bdev, to_bytes(ec->u_bs), 1, 0, NULL, NULL);
+	if (IS_ERR(ec->bufio)) {
+		ti->error = "Cannot create dm bufio client";
+		r = PTR_ERR(ec->bufio);
+		ec->bufio = NULL;
+		goto bad;
+	}
+
+	ec->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
+	if (!ec->wq) {
+		ti->error = "Cannot create dm-" DM_MSG_PREFIX " workqueue";
+		r = -ENOMEM;
+		goto bad;
+	}
+
+	ec->block_shift = __ffs(ec->u_bs);
+	INIT_WORK(&ec->ws, &__ebs_process_bios);
+	bio_list_init(&ec->bios_in);
+	spin_lock_init(&ec->lock);
+
+	ti->num_flush_bios = 1;
+	ti->num_discard_bios = 1;
+	ti->num_secure_erase_bios = 0;
+	ti->num_write_same_bios = 0;
+	ti->num_write_zeroes_bios = 0;
+	return 0;
+bad:
+	ebs_dtr(ti);
+	return r;
+}
+
+static void ebs_dtr(struct dm_target *ti)
+{
+	struct ebs_c *ec = ti->private;
+
+	if (ec->wq)
+		destroy_workqueue(ec->wq);
+	if (ec->bufio)
+		dm_bufio_client_destroy(ec->bufio);
+	if (ec->dev)
+		dm_put_device(ti, ec->dev);
+	kfree(ec);
+}
+
+static int ebs_map(struct dm_target *ti, struct bio *bio)
+{
+	struct ebs_c *ec = ti->private;
+
+	bio_set_dev(bio, ec->dev->bdev);
+	bio->bi_iter.bi_sector = ec->start + dm_target_offset(ti, bio->bi_iter.bi_sector);
+
+	if (unlikely(bio->bi_opf & REQ_OP_FLUSH))
+		return DM_MAPIO_REMAPPED;
+	/*
+	 * Only queue for bufio processing in case of partial or overlapping buffers
+	 * -or-
+	 * emulation with ebs == ubs aiming for tests of dm-bufio overhead.
+	 */
+	if (likely(__block_mod(bio->bi_iter.bi_sector, ec->u_bs) ||
+		   __block_mod(bio_end_sector(bio), ec->u_bs) ||
+		   ec->e_bs == ec->u_bs)) {
+		spin_lock_irq(&ec->lock);
+		bio_list_add(&ec->bios_in, bio);
+		spin_unlock_irq(&ec->lock);
+
+		queue_work(ec->wq, &ec->ws);
+
+		return DM_MAPIO_SUBMITTED;
+	}
+
+	/* Forget any buffer content relative to this direct backing device I/O. */
+	__ebs_forget_bio(ec, bio);
+
+	return DM_MAPIO_REMAPPED;
+}
+
+static void ebs_status(struct dm_target *ti, status_type_t type,
+		       unsigned status_flags, char *result, unsigned maxlen)
+{
+	struct ebs_c *ec = ti->private;
+
+	switch (type) {
+	case STATUSTYPE_INFO:
+		*result = '\0';
+		break;
+	case STATUSTYPE_TABLE:
+		snprintf(result, maxlen, ec->u_bs_set ? "%s %llu %u %u" : "%s %llu %u",
+			 ec->dev->name, (unsigned long long) ec->start, ec->e_bs, ec->u_bs);
+		break;
+	}
+}
+
+static int ebs_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
+{
+	struct ebs_c *ec = ti->private;
+	struct dm_dev *dev = ec->dev;
+
+	/*
+	 * Only pass ioctls through if the device sizes match exactly.
+	 */
+	*bdev = dev->bdev;
+	return !!(ec->start || ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT);
+}
+
+static void ebs_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+	struct ebs_c *ec = ti->private;
+
+	limits->logical_block_size = to_bytes(ec->e_bs);
+	limits->physical_block_size = to_bytes(ec->u_bs);
+	limits->alignment_offset = limits->physical_block_size;
+	blk_limits_io_min(limits, limits->logical_block_size);
+}
+
+static int ebs_iterate_devices(struct dm_target *ti,
+				  iterate_devices_callout_fn fn, void *data)
+{
+	struct ebs_c *ec = ti->private;
+
+	return fn(ti, ec->dev, ec->start, ti->len, data);
+}
+
+static struct target_type ebs_target = {
+	.name		 = "ebs",
+	.version	 = {1, 0, 1},
+	.features	 = DM_TARGET_PASSES_INTEGRITY,
+	.module		 = THIS_MODULE,
+	.ctr		 = ebs_ctr,
+	.dtr		 = ebs_dtr,
+	.map		 = ebs_map,
+	.status		 = ebs_status,
+	.io_hints	 = ebs_io_hints,
+	.prepare_ioctl	 = ebs_prepare_ioctl,
+	.iterate_devices = ebs_iterate_devices,
+};
+
+static int __init dm_ebs_init(void)
+{
+	int r = dm_register_target(&ebs_target);
+
+	if (r < 0)
+		DMERR("register failed %d", r);
+
+	return r;
+}
+
+static void dm_ebs_exit(void)
+{
+	dm_unregister_target(&ebs_target);
+}
+
+module_init(dm_ebs_init);
+module_exit(dm_ebs_exit);
+
+MODULE_AUTHOR("Heinz Mauelshagen <dm-devel@redhat.com>");
+MODULE_DESCRIPTION(DM_NAME " emulated block size target");
+MODULE_LICENSE("GPL");
diff --git a/drivers/md/dm-historical-service-time.c b/drivers/md/dm-historical-service-time.c
new file mode 100644
index 000000000000..186f91e2752c
--- /dev/null
+++ b/drivers/md/dm-historical-service-time.c
@@ -0,0 +1,561 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Historical Service Time
+ *
+ *  Keeps a time-weighted exponential moving average of the historical
+ *  service time. Estimates future service time based on the historical
+ *  service time and the number of outstanding requests.
+ *
+ *  Marks paths stale if they have not finished within hst *
+ *  num_paths. If a path is stale and unused, we will send a single
+ *  request to probe in case the path has improved. This situation
+ *  generally arises if the path is so much worse than others that it
+ *  will never have the best estimated service time, or if the entire
+ *  multipath device is unused. If a path is stale and in use, limit the
+ *  number of requests it can receive with the assumption that the path
+ *  has become degraded.
+ *
+ *  To avoid repeatedly calculating exponents for time weighting, times
+ *  are split into HST_WEIGHT_COUNT buckets each (1 >> HST_BUCKET_SHIFT)
+ *  ns, and the weighting is pre-calculated.
+ *
+ */
+
+#include "dm.h"
+#include "dm-path-selector.h"
+
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+
+#define DM_MSG_PREFIX	"multipath historical-service-time"
+#define HST_MIN_IO 1
+#define HST_VERSION "0.1.1"
+
+#define HST_FIXED_SHIFT 10  /* 10 bits of decimal precision */
+#define HST_FIXED_MAX (ULLONG_MAX >> HST_FIXED_SHIFT)
+#define HST_FIXED_1 (1 << HST_FIXED_SHIFT)
+#define HST_FIXED_95 972
+#define HST_MAX_INFLIGHT HST_FIXED_1
+#define HST_BUCKET_SHIFT 24 /* Buckets are ~ 16ms */
+#define HST_WEIGHT_COUNT 64ULL
+
+struct selector {
+	struct list_head valid_paths;
+	struct list_head failed_paths;
+	int valid_count;
+	spinlock_t lock;
+
+	unsigned int weights[HST_WEIGHT_COUNT];
+	unsigned int threshold_multiplier;
+};
+
+struct path_info {
+	struct list_head list;
+	struct dm_path *path;
+	unsigned int repeat_count;
+
+	spinlock_t lock;
+
+	u64 historical_service_time; /* Fixed point */
+
+	u64 stale_after;
+	u64 last_finish;
+
+	u64 outstanding;
+};
+
+/**
+ * fixed_power - compute: x^n, in O(log n) time
+ *
+ * @x:         base of the power
+ * @frac_bits: fractional bits of @x
+ * @n:         power to raise @x to.
+ *
+ * By exploiting the relation between the definition of the natural power
+ * function: x^n := x*x*...*x (x multiplied by itself for n times), and
+ * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
+ * (where: n_i \elem {0, 1}, the binary vector representing n),
+ * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
+ * of course trivially computable in O(log_2 n), the length of our binary
+ * vector.
+ *
+ * (see: kernel/sched/loadavg.c)
+ */
+static u64 fixed_power(u64 x, unsigned int frac_bits, unsigned int n)
+{
+	unsigned long result = 1UL << frac_bits;
+
+	if (n) {
+		for (;;) {
+			if (n & 1) {
+				result *= x;
+				result += 1UL << (frac_bits - 1);
+				result >>= frac_bits;
+			}
+			n >>= 1;
+			if (!n)
+				break;
+			x *= x;
+			x += 1UL << (frac_bits - 1);
+			x >>= frac_bits;
+		}
+	}
+
+	return result;
+}
+
+/*
+ * Calculate the next value of an exponential moving average
+ * a_1 = a_0 * e + a * (1 - e)
+ *
+ * @last: [0, ULLONG_MAX >> HST_FIXED_SHIFT]
+ * @next: [0, ULLONG_MAX >> HST_FIXED_SHIFT]
+ * @weight: [0, HST_FIXED_1]
+ *
+ * Note:
+ *   To account for multiple periods in the same calculation,
+ *   a_n = a_0 * e^n + a * (1 - e^n),
+ *   so call fixed_ema(last, next, pow(weight, N))
+ */
+static u64 fixed_ema(u64 last, u64 next, u64 weight)
+{
+	last *= weight;
+	last += next * (HST_FIXED_1 - weight);
+	last += 1ULL << (HST_FIXED_SHIFT - 1);
+	return last >> HST_FIXED_SHIFT;
+}
+
+static struct selector *alloc_selector(void)
+{
+	struct selector *s = kmalloc(sizeof(*s), GFP_KERNEL);
+
+	if (s) {
+		INIT_LIST_HEAD(&s->valid_paths);
+		INIT_LIST_HEAD(&s->failed_paths);
+		spin_lock_init(&s->lock);
+		s->valid_count = 0;
+	}
+
+	return s;
+}
+
+/*
+ * Get the weight for a given time span.
+ */
+static u64 hst_weight(struct path_selector *ps, u64 delta)
+{
+	struct selector *s = ps->context;
+	int bucket = clamp(delta >> HST_BUCKET_SHIFT, 0ULL,
+			   HST_WEIGHT_COUNT - 1);
+
+	return s->weights[bucket];
+}
+
+/*
+ * Set up the weights array.
+ *
+ * weights[len-1] = 0
+ * weights[n] = base ^ (n + 1)
+ */
+static void hst_set_weights(struct path_selector *ps, unsigned int base)
+{
+	struct selector *s = ps->context;
+	int i;
+
+	if (base >= HST_FIXED_1)
+		return;
+
+	for (i = 0; i < HST_WEIGHT_COUNT - 1; i++)
+		s->weights[i] = fixed_power(base, HST_FIXED_SHIFT, i + 1);
+	s->weights[HST_WEIGHT_COUNT - 1] = 0;
+}
+
+static int hst_create(struct path_selector *ps, unsigned int argc, char **argv)
+{
+	struct selector *s;
+	unsigned int base_weight = HST_FIXED_95;
+	unsigned int threshold_multiplier = 0;
+	char dummy;
+
+	/*
+	 * Arguments: [<base_weight> [<threshold_multiplier>]]
+	 *   <base_weight>: Base weight for ema [0, 1024) 10-bit fixed point. A
+	 *                  value of 0 will completely ignore any history.
+	 *                  If not given, default (HST_FIXED_95) is used.
+	 *   <threshold_multiplier>: Minimum threshold multiplier for paths to
+	 *                  be considered different. That is, a path is
+	 *                  considered different iff (p1 > N * p2) where p1
+	 *                  is the path with higher service time. A threshold
+	 *                  of 1 or 0 has no effect. Defaults to 0.
+	 */
+	if (argc > 2)
+		return -EINVAL;
+
+	if (argc && (sscanf(argv[0], "%u%c", &base_weight, &dummy) != 1 ||
+	     base_weight >= HST_FIXED_1)) {
+		return -EINVAL;
+	}
+
+	if (argc > 1 && (sscanf(argv[1], "%u%c",
+				&threshold_multiplier, &dummy) != 1)) {
+		return -EINVAL;
+	}
+
+	s = alloc_selector();
+	if (!s)
+		return -ENOMEM;
+
+	ps->context = s;
+
+	hst_set_weights(ps, base_weight);
+	s->threshold_multiplier = threshold_multiplier;
+	return 0;
+}
+
+static void free_paths(struct list_head *paths)
+{
+	struct path_info *pi, *next;
+
+	list_for_each_entry_safe(pi, next, paths, list) {
+		list_del(&pi->list);
+		kfree(pi);
+	}
+}
+
+static void hst_destroy(struct path_selector *ps)
+{
+	struct selector *s = ps->context;
+
+	free_paths(&s->valid_paths);
+	free_paths(&s->failed_paths);
+	kfree(s);
+	ps->context = NULL;
+}
+
+static int hst_status(struct path_selector *ps, struct dm_path *path,
+		     status_type_t type, char *result, unsigned int maxlen)
+{
+	unsigned int sz = 0;
+	struct path_info *pi;
+
+	if (!path) {
+		struct selector *s = ps->context;
+
+		DMEMIT("2 %u %u ", s->weights[0], s->threshold_multiplier);
+	} else {
+		pi = path->pscontext;
+
+		switch (type) {
+		case STATUSTYPE_INFO:
+			DMEMIT("%llu %llu %llu ", pi->historical_service_time,
+			       pi->outstanding, pi->stale_after);
+			break;
+		case STATUSTYPE_TABLE:
+			DMEMIT("0 ");
+			break;
+		}
+	}
+
+	return sz;
+}
+
+static int hst_add_path(struct path_selector *ps, struct dm_path *path,
+		       int argc, char **argv, char **error)
+{
+	struct selector *s = ps->context;
+	struct path_info *pi;
+	unsigned int repeat_count = HST_MIN_IO;
+	char dummy;
+	unsigned long flags;
+
+	/*
+	 * Arguments: [<repeat_count>]
+	 *   <repeat_count>: The number of I/Os before switching path.
+	 *                   If not given, default (HST_MIN_IO) is used.
+	 */
+	if (argc > 1) {
+		*error = "historical-service-time ps: incorrect number of arguments";
+		return -EINVAL;
+	}
+
+	if (argc && (sscanf(argv[0], "%u%c", &repeat_count, &dummy) != 1)) {
+		*error = "historical-service-time ps: invalid repeat count";
+		return -EINVAL;
+	}
+
+	/* allocate the path */
+	pi = kmalloc(sizeof(*pi), GFP_KERNEL);
+	if (!pi) {
+		*error = "historical-service-time ps: Error allocating path context";
+		return -ENOMEM;
+	}
+
+	pi->path = path;
+	pi->repeat_count = repeat_count;
+
+	pi->historical_service_time = HST_FIXED_1;
+
+	spin_lock_init(&pi->lock);
+	pi->outstanding = 0;
+
+	pi->stale_after = 0;
+	pi->last_finish = 0;
+
+	path->pscontext = pi;
+
+	spin_lock_irqsave(&s->lock, flags);
+	list_add_tail(&pi->list, &s->valid_paths);
+	s->valid_count++;
+	spin_unlock_irqrestore(&s->lock, flags);
+
+	return 0;
+}
+
+static void hst_fail_path(struct path_selector *ps, struct dm_path *path)
+{
+	struct selector *s = ps->context;
+	struct path_info *pi = path->pscontext;
+	unsigned long flags;
+
+	spin_lock_irqsave(&s->lock, flags);
+	list_move(&pi->list, &s->failed_paths);
+	s->valid_count--;
+	spin_unlock_irqrestore(&s->lock, flags);
+}
+
+static int hst_reinstate_path(struct path_selector *ps, struct dm_path *path)
+{
+	struct selector *s = ps->context;
+	struct path_info *pi = path->pscontext;
+	unsigned long flags;
+
+	spin_lock_irqsave(&s->lock, flags);
+	list_move_tail(&pi->list, &s->valid_paths);
+	s->valid_count++;
+	spin_unlock_irqrestore(&s->lock, flags);
+
+	return 0;
+}
+
+static void hst_fill_compare(struct path_info *pi, u64 *hst,
+			     u64 *out, u64 *stale)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&pi->lock, flags);
+	*hst = pi->historical_service_time;
+	*out = pi->outstanding;
+	*stale = pi->stale_after;
+	spin_unlock_irqrestore(&pi->lock, flags);
+}
+
+/*
+ * Compare the estimated service time of 2 paths, pi1 and pi2,
+ * for the incoming I/O.
+ *
+ * Returns:
+ * < 0 : pi1 is better
+ * 0   : no difference between pi1 and pi2
+ * > 0 : pi2 is better
+ *
+ */
+static long long hst_compare(struct path_info *pi1, struct path_info *pi2,
+			     u64 time_now, struct path_selector *ps)
+{
+	struct selector *s = ps->context;
+	u64 hst1, hst2;
+	long long out1, out2, stale1, stale2;
+	int pi2_better, over_threshold;
+
+	hst_fill_compare(pi1, &hst1, &out1, &stale1);
+	hst_fill_compare(pi2, &hst2, &out2, &stale2);
+
+	/* Check here if estimated latency for two paths are too similar.
+	 * If this is the case, we skip extra calculation and just compare
+	 * outstanding requests. In this case, any unloaded paths will
+	 * be preferred.
+	 */
+	if (hst1 > hst2)
+		over_threshold = hst1 > (s->threshold_multiplier * hst2);
+	else
+		over_threshold = hst2 > (s->threshold_multiplier * hst1);
+
+	if (!over_threshold)
+		return out1 - out2;
+
+	/*
+	 * If an unloaded path is stale, choose it. If both paths are unloaded,
+	 * choose path that is the most stale.
+	 * (If one path is loaded, choose the other)
+	 */
+	if ((!out1 && stale1 < time_now) || (!out2 && stale2 < time_now) ||
+	    (!out1 && !out2))
+		return (!out2 * stale1) - (!out1 * stale2);
+
+	/* Compare estimated service time. If outstanding is the same, we
+	 * don't need to multiply
+	 */
+	if (out1 == out2) {
+		pi2_better = hst1 > hst2;
+	} else {
+		/* Potential overflow with out >= 1024 */
+		if (unlikely(out1 >= HST_MAX_INFLIGHT ||
+			     out2 >= HST_MAX_INFLIGHT)) {
+			/* If over 1023 in-flights, we may overflow if hst
+			 * is at max. (With this shift we still overflow at
+			 * 1048576 in-flights, which is high enough).
+			 */
+			hst1 >>= HST_FIXED_SHIFT;
+			hst2 >>= HST_FIXED_SHIFT;
+		}
+		pi2_better = (1 + out1) * hst1 > (1 + out2) * hst2;
+	}
+
+	/* In the case that the 'winner' is stale, limit to equal usage. */
+	if (pi2_better) {
+		if (stale2 < time_now)
+			return out1 - out2;
+		return 1;
+	}
+	if (stale1 < time_now)
+		return out1 - out2;
+	return -1;
+}
+
+static struct dm_path *hst_select_path(struct path_selector *ps,
+				       size_t nr_bytes)
+{
+	struct selector *s = ps->context;
+	struct path_info *pi = NULL, *best = NULL;
+	u64 time_now = sched_clock();
+	struct dm_path *ret = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&s->lock, flags);
+	if (list_empty(&s->valid_paths))
+		goto out;
+
+	list_for_each_entry(pi, &s->valid_paths, list) {
+		if (!best || (hst_compare(pi, best, time_now, ps) < 0))
+			best = pi;
+	}
+
+	if (!best)
+		goto out;
+
+	/* Move last used path to end (least preferred in case of ties) */
+	list_move_tail(&best->list, &s->valid_paths);
+
+	ret = best->path;
+
+out:
+	spin_unlock_irqrestore(&s->lock, flags);
+	return ret;
+}
+
+static int hst_start_io(struct path_selector *ps, struct dm_path *path,
+			size_t nr_bytes)
+{
+	struct path_info *pi = path->pscontext;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pi->lock, flags);
+	pi->outstanding++;
+	spin_unlock_irqrestore(&pi->lock, flags);
+
+	return 0;
+}
+
+static u64 path_service_time(struct path_info *pi, u64 start_time)
+{
+	u64 sched_now = ktime_get_ns();
+
+	/* if a previous disk request has finished after this IO was
+	 * sent to the hardware, pretend the submission happened
+	 * serially.
+	 */
+	if (time_after64(pi->last_finish, start_time))
+		start_time = pi->last_finish;
+
+	pi->last_finish = sched_now;
+	if (time_before64(sched_now, start_time))
+		return 0;
+
+	return sched_now - start_time;
+}
+
+static int hst_end_io(struct path_selector *ps, struct dm_path *path,
+		      size_t nr_bytes, u64 start_time)
+{
+	struct path_info *pi = path->pscontext;
+	struct selector *s = ps->context;
+	unsigned long flags;
+	u64 st;
+
+	spin_lock_irqsave(&pi->lock, flags);
+
+	st = path_service_time(pi, start_time);
+	pi->outstanding--;
+	pi->historical_service_time =
+		fixed_ema(pi->historical_service_time,
+			  min(st * HST_FIXED_1, HST_FIXED_MAX),
+			  hst_weight(ps, st));
+
+	/*
+	 * On request end, mark path as fresh. If a path hasn't
+	 * finished any requests within the fresh period, the estimated
+	 * service time is considered too optimistic and we limit the
+	 * maximum requests on that path.
+	 */
+	pi->stale_after = pi->last_finish +
+		(s->valid_count * (pi->historical_service_time >> HST_FIXED_SHIFT));
+
+	spin_unlock_irqrestore(&pi->lock, flags);
+
+	return 0;
+}
+
+static struct path_selector_type hst_ps = {
+	.name		= "historical-service-time",
+	.module		= THIS_MODULE,
+	.table_args	= 1,
+	.info_args	= 3,
+	.create		= hst_create,
+	.destroy	= hst_destroy,
+	.status		= hst_status,
+	.add_path	= hst_add_path,
+	.fail_path	= hst_fail_path,
+	.reinstate_path	= hst_reinstate_path,
+	.select_path	= hst_select_path,
+	.start_io	= hst_start_io,
+	.end_io		= hst_end_io,
+};
+
+static int __init dm_hst_init(void)
+{
+	int r = dm_register_path_selector(&hst_ps);
+
+	if (r < 0)
+		DMERR("register failed %d", r);
+
+	DMINFO("version " HST_VERSION " loaded");
+
+	return r;
+}
+
+static void __exit dm_hst_exit(void)
+{
+	int r = dm_unregister_path_selector(&hst_ps);
+
+	if (r < 0)
+		DMERR("unregister failed %d", r);
+}
+
+module_init(dm_hst_init);
+module_exit(dm_hst_exit);
+
+MODULE_DESCRIPTION(DM_NAME " measured service time oriented path selector");
+MODULE_AUTHOR("Khazhismel Kumykov <khazhy@google.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 84cb04904fab..81dc5ff08909 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -92,7 +92,7 @@ struct journal_entry {
 		} s;
 		__u64 sector;
 	} u;
-	commit_id_t last_bytes[0];
+	commit_id_t last_bytes[];
 	/* __u8 tag[0]; */
 };
 
@@ -1553,8 +1553,6 @@ static void integrity_metadata(struct work_struct *w)
 		char checksums_onstack[max((size_t)HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
 		sector_t sector;
 		unsigned sectors_to_process;
-		sector_t save_metadata_block;
-		unsigned save_metadata_offset;
 
 		if (unlikely(ic->mode == 'R'))
 			goto skip_io;
@@ -1605,8 +1603,6 @@ static void integrity_metadata(struct work_struct *w)
 			goto skip_io;
 		}
 
-		save_metadata_block = dio->metadata_block;
-		save_metadata_offset = dio->metadata_offset;
 		sector = dio->range.logical_sector;
 		sectors_to_process = dio->range.n_sectors;
 
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 8ea20b56b4d6..e3d35c6c9f71 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -127,7 +127,7 @@ struct pending_block {
 	char *data;
 	u32 datalen;
 	struct list_head list;
-	struct bio_vec vecs[0];
+	struct bio_vec vecs[];
 };
 
 struct per_bio_data {
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 3e500098132f..78cff42d987e 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -439,7 +439,7 @@ failed:
 }
 
 /*
- * dm_report_EIO() is a macro instead of a function to make pr_debug()
+ * dm_report_EIO() is a macro instead of a function to make pr_debug_ratelimited()
  * report the function name and line number of the function from which
  * it has been invoked.
  */
@@ -447,43 +447,25 @@ failed:
 do {									\
 	struct mapped_device *md = dm_table_get_md((m)->ti->table);	\
 									\
-	pr_debug("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d\n", \
-		 dm_device_name(md),					\
-		 test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags),	\
-		 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags),	\
-		 dm_noflush_suspending((m)->ti));			\
+	DMDEBUG_LIMIT("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d", \
+		      dm_device_name(md),				\
+		      test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags),	\
+		      test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
+		      dm_noflush_suspending((m)->ti));			\
 } while (0)
 
 /*
  * Check whether bios must be queued in the device-mapper core rather
  * than here in the target.
- *
- * If MPATHF_QUEUE_IF_NO_PATH and MPATHF_SAVED_QUEUE_IF_NO_PATH hold
- * the same value then we are not between multipath_presuspend()
- * and multipath_resume() calls and we have no need to check
- * for the DMF_NOFLUSH_SUSPENDING flag.
  */
-static bool __must_push_back(struct multipath *m, unsigned long flags)
+static bool __must_push_back(struct multipath *m)
 {
-	return ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) !=
-		 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &flags)) &&
-		dm_noflush_suspending(m->ti));
+	return dm_noflush_suspending(m->ti);
 }
 
-/*
- * Following functions use READ_ONCE to get atomic access to
- * all m->flags to avoid taking spinlock
- */
 static bool must_push_back_rq(struct multipath *m)
 {
-	unsigned long flags = READ_ONCE(m->flags);
-	return test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) || __must_push_back(m, flags);
-}
-
-static bool must_push_back_bio(struct multipath *m)
-{
-	unsigned long flags = READ_ONCE(m->flags);
-	return __must_push_back(m, flags);
+	return test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) || __must_push_back(m);
 }
 
 /*
@@ -567,7 +549,8 @@ static void multipath_release_clone(struct request *clone,
 		if (pgpath && pgpath->pg->ps.type->end_io)
 			pgpath->pg->ps.type->end_io(&pgpath->pg->ps,
 						    &pgpath->path,
-						    mpio->nr_bytes);
+						    mpio->nr_bytes,
+						    clone->io_start_time_ns);
 	}
 
 	blk_put_request(clone);
@@ -619,7 +602,7 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio,
 		return DM_MAPIO_SUBMITTED;
 
 	if (!pgpath) {
-		if (must_push_back_bio(m))
+		if (__must_push_back(m))
 			return DM_MAPIO_REQUEUE;
 		dm_report_EIO(m);
 		return DM_MAPIO_KILL;
@@ -709,15 +692,38 @@ static void process_queued_bios(struct work_struct *work)
  * If we run out of usable paths, should we queue I/O or error it?
  */
 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
-			    bool save_old_value)
+			    bool save_old_value, const char *caller)
 {
 	unsigned long flags;
+	bool queue_if_no_path_bit, saved_queue_if_no_path_bit;
+	const char *dm_dev_name = dm_device_name(dm_table_get_md(m->ti->table));
+
+	DMDEBUG("%s: %s caller=%s queue_if_no_path=%d save_old_value=%d",
+		dm_dev_name, __func__, caller, queue_if_no_path, save_old_value);
 
 	spin_lock_irqsave(&m->lock, flags);
-	assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags,
-		   (save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
-		   (!save_old_value && queue_if_no_path));
+
+	queue_if_no_path_bit = test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
+	saved_queue_if_no_path_bit = test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
+
+	if (save_old_value) {
+		if (unlikely(!queue_if_no_path_bit && saved_queue_if_no_path_bit)) {
+			DMERR("%s: QIFNP disabled but saved as enabled, saving again loses state, not saving!",
+			      dm_dev_name);
+		} else
+			assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path_bit);
+	} else if (!queue_if_no_path && saved_queue_if_no_path_bit) {
+		/* due to "fail_if_no_path" message, need to honor it. */
+		clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
+	}
 	assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path);
+
+	DMDEBUG("%s: after %s changes; QIFNP = %d; SQIFNP = %d; DNFS = %d",
+		dm_dev_name, __func__,
+		test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
+		test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
+		dm_noflush_suspending(m->ti));
+
 	spin_unlock_irqrestore(&m->lock, flags);
 
 	if (!queue_if_no_path) {
@@ -738,7 +744,7 @@ static void queue_if_no_path_timeout_work(struct timer_list *t)
 	struct mapped_device *md = dm_table_get_md(m->ti->table);
 
 	DMWARN("queue_if_no_path timeout on %s, failing queued IO", dm_device_name(md));
-	queue_if_no_path(m, false, false);
+	queue_if_no_path(m, false, false, __func__);
 }
 
 /*
@@ -1078,7 +1084,7 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m)
 		argc--;
 
 		if (!strcasecmp(arg_name, "queue_if_no_path")) {
-			r = queue_if_no_path(m, true, false);
+			r = queue_if_no_path(m, true, false, __func__);
 			continue;
 		}
 
@@ -1279,7 +1285,9 @@ static int fail_path(struct pgpath *pgpath)
 	if (!pgpath->is_active)
 		goto out;
 
-	DMWARN("Failing path %s.", pgpath->path.dev->name);
+	DMWARN("%s: Failing path %s.",
+	       dm_device_name(dm_table_get_md(m->ti->table)),
+	       pgpath->path.dev->name);
 
 	pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
 	pgpath->is_active = false;
@@ -1318,7 +1326,9 @@ static int reinstate_path(struct pgpath *pgpath)
 	if (pgpath->is_active)
 		goto out;
 
-	DMWARN("Reinstating path %s.", pgpath->path.dev->name);
+	DMWARN("%s: Reinstating path %s.",
+	       dm_device_name(dm_table_get_md(m->ti->table)),
+	       pgpath->path.dev->name);
 
 	r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
 	if (r)
@@ -1617,7 +1627,8 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
 		struct path_selector *ps = &pgpath->pg->ps;
 
 		if (ps->type->end_io)
-			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
+			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
+					 clone->io_start_time_ns);
 	}
 
 	return r;
@@ -1640,7 +1651,7 @@ static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
 
 	if (atomic_read(&m->nr_valid_paths) == 0 &&
 	    !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
-		if (must_push_back_bio(m)) {
+		if (__must_push_back(m)) {
 			r = DM_ENDIO_REQUEUE;
 		} else {
 			dm_report_EIO(m);
@@ -1661,23 +1672,27 @@ done:
 		struct path_selector *ps = &pgpath->pg->ps;
 
 		if (ps->type->end_io)
-			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
+			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
+					 dm_start_time_ns_from_clone(clone));
 	}
 
 	return r;
 }
 
 /*
- * Suspend can't complete until all the I/O is processed so if
- * the last path fails we must error any remaining I/O.
- * Note that if the freeze_bdev fails while suspending, the
- * queue_if_no_path state is lost - userspace should reset it.
+ * Suspend with flush can't complete until all the I/O is processed
+ * so if the last path fails we must error any remaining I/O.
+ * - Note that if the freeze_bdev fails while suspending, the
+ *   queue_if_no_path state is lost - userspace should reset it.
+ * Otherwise, during noflush suspend, queue_if_no_path will not change.
  */
 static void multipath_presuspend(struct dm_target *ti)
 {
 	struct multipath *m = ti->private;
 
-	queue_if_no_path(m, false, true);
+	/* FIXME: bio-based shouldn't need to always disable queue_if_no_path */
+	if (m->queue_mode == DM_TYPE_BIO_BASED || !dm_noflush_suspending(m->ti))
+		queue_if_no_path(m, false, true, __func__);
 }
 
 static void multipath_postsuspend(struct dm_target *ti)
@@ -1698,8 +1713,16 @@ static void multipath_resume(struct dm_target *ti)
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-	assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags,
-		   test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
+	if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) {
+		set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
+		clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
+	}
+
+	DMDEBUG("%s: %s finished; QIFNP = %d; SQIFNP = %d",
+		dm_device_name(dm_table_get_md(m->ti->table)), __func__,
+		test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
+		test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
+
 	spin_unlock_irqrestore(&m->lock, flags);
 }
 
@@ -1859,13 +1882,13 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv,
 
 	if (argc == 1) {
 		if (!strcasecmp(argv[0], "queue_if_no_path")) {
-			r = queue_if_no_path(m, true, false);
+			r = queue_if_no_path(m, true, false, __func__);
 			spin_lock_irqsave(&m->lock, flags);
 			enable_nopath_timeout(m);
 			spin_unlock_irqrestore(&m->lock, flags);
 			goto out;
 		} else if (!strcasecmp(argv[0], "fail_if_no_path")) {
-			r = queue_if_no_path(m, false, false);
+			r = queue_if_no_path(m, false, false, __func__);
 			disable_nopath_timeout(m);
 			goto out;
 		}
@@ -1918,7 +1941,7 @@ static int multipath_prepare_ioctl(struct dm_target *ti,
 	int r;
 
 	current_pgpath = READ_ONCE(m->current_pgpath);
-	if (!current_pgpath)
+	if (!current_pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
 		current_pgpath = choose_pgpath(m, 0);
 
 	if (current_pgpath) {
diff --git a/drivers/md/dm-path-selector.h b/drivers/md/dm-path-selector.h
index b6eb5365b1a4..c47bc0e20275 100644
--- a/drivers/md/dm-path-selector.h
+++ b/drivers/md/dm-path-selector.h
@@ -74,7 +74,7 @@ struct path_selector_type {
 	int (*start_io) (struct path_selector *ps, struct dm_path *path,
 			 size_t nr_bytes);
 	int (*end_io) (struct path_selector *ps, struct dm_path *path,
-		       size_t nr_bytes);
+		       size_t nr_bytes, u64 start_time);
 };
 
 /* Register a path selector */
diff --git a/drivers/md/dm-queue-length.c b/drivers/md/dm-queue-length.c
index 969c4f1a3633..5fd018d18418 100644
--- a/drivers/md/dm-queue-length.c
+++ b/drivers/md/dm-queue-length.c
@@ -227,7 +227,7 @@ static int ql_start_io(struct path_selector *ps, struct dm_path *path,
 }
 
 static int ql_end_io(struct path_selector *ps, struct dm_path *path,
-		     size_t nr_bytes)
+		     size_t nr_bytes, u64 start_time)
 {
 	struct path_info *pi = path->pscontext;
 
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 9a18bef0a5ff..10e8b2fe787b 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -254,7 +254,7 @@ struct raid_set {
 		int mode;
 	} journal_dev;
 
-	struct raid_dev dev[0];
+	struct raid_dev dev[];
 };
 
 static void rs_config_backup(struct raid_set *rs, struct rs_layout *l)
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 089aed57e083..2f655d9f4200 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -83,7 +83,7 @@ struct mirror_set {
 	struct work_struct trigger_event;
 
 	unsigned nr_mirrors;
-	struct mirror mirror[0];
+	struct mirror mirror[];
 };
 
 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle,
diff --git a/drivers/md/dm-service-time.c b/drivers/md/dm-service-time.c
index f006a9005593..9cfda665e9eb 100644
--- a/drivers/md/dm-service-time.c
+++ b/drivers/md/dm-service-time.c
@@ -309,7 +309,7 @@ static int st_start_io(struct path_selector *ps, struct dm_path *path,
 }
 
 static int st_end_io(struct path_selector *ps, struct dm_path *path,
-		     size_t nr_bytes)
+		     size_t nr_bytes, u64 start_time)
 {
 	struct path_info *pi = path->pscontext;
 
diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 71417048256a..35d368c418d0 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -56,7 +56,7 @@ struct dm_stat {
 	size_t percpu_alloc_size;
 	size_t histogram_alloc_size;
 	struct dm_stat_percpu *stat_percpu[NR_CPUS];
-	struct dm_stat_shared stat_shared[0];
+	struct dm_stat_shared stat_shared[];
 };
 
 #define STAT_PRECISE_TIMESTAMPS		1
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index fa813c0f993d..151d022b032d 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -41,7 +41,7 @@ struct stripe_c {
 	/* Work struct used for triggering events*/
 	struct work_struct trigger_event;
 
-	struct stripe stripe[0];
+	struct stripe stripe[];
 };
 
 /*
diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c
index 8a0f057b8122..bff4c7fa1cd2 100644
--- a/drivers/md/dm-switch.c
+++ b/drivers/md/dm-switch.c
@@ -53,7 +53,7 @@ struct switch_ctx {
 	/*
 	 * Array of dm devices to switch between.
 	 */
-	struct switch_path path_list[0];
+	struct switch_path path_list[];
 };
 
 static struct switch_ctx *alloc_switch_ctx(struct dm_target *ti, unsigned nr_paths,
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 613c171b1b6d..74f3c506f084 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -234,10 +234,6 @@ static int persistent_memory_claim(struct dm_writecache *wc)
 
 	wc->memory_vmapped = false;
 
-	if (!wc->ssd_dev->dax_dev) {
-		r = -EOPNOTSUPP;
-		goto err1;
-	}
 	s = wc->memory_map_size;
 	p = s >> PAGE_SHIFT;
 	if (!p) {
@@ -1143,6 +1139,42 @@ static int writecache_message(struct dm_target *ti, unsigned argc, char **argv,
 	return r;
 }
 
+static void memcpy_flushcache_optimized(void *dest, void *source, size_t size)
+{
+	/*
+	 * clflushopt performs better with block size 1024, 2048, 4096
+	 * non-temporal stores perform better with block size 512
+	 *
+	 * block size   512             1024            2048            4096
+	 * movnti       496 MB/s        642 MB/s        725 MB/s        744 MB/s
+	 * clflushopt   373 MB/s        688 MB/s        1.1 GB/s        1.2 GB/s
+	 *
+	 * We see that movnti performs better for 512-byte blocks, and
+	 * clflushopt performs better for 1024-byte and larger blocks. So, we
+	 * prefer clflushopt for sizes >= 768.
+	 *
+	 * NOTE: this happens to be the case now (with dm-writecache's single
+	 * threaded model) but re-evaluate this once memcpy_flushcache() is
+	 * enabled to use movdir64b which might invalidate this performance
+	 * advantage seen with cache-allocating-writes plus flushing.
+	 */
+#ifdef CONFIG_X86
+	if (static_cpu_has(X86_FEATURE_CLFLUSHOPT) &&
+	    likely(boot_cpu_data.x86_clflush_size == 64) &&
+	    likely(size >= 768)) {
+		do {
+			memcpy((void *)dest, (void *)source, 64);
+			clflushopt((void *)dest);
+			dest += 64;
+			source += 64;
+			size -= 64;
+		} while (size >= 64);
+		return;
+	}
+#endif
+	memcpy_flushcache(dest, source, size);
+}
+
 static void bio_copy_block(struct dm_writecache *wc, struct bio *bio, void *data)
 {
 	void *buf;
@@ -1168,7 +1200,7 @@ static void bio_copy_block(struct dm_writecache *wc, struct bio *bio, void *data
 			}
 		} else {
 			flush_dcache_page(bio_page(bio));
-			memcpy_flushcache(data, buf, size);
+			memcpy_flushcache_optimized(data, buf, size);
 		}
 
 		bvec_kunmap_irq(buf, &flags);
diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c
index bf2245370305..130b5a6d9f12 100644
--- a/drivers/md/dm-zoned-metadata.c
+++ b/drivers/md/dm-zoned-metadata.c
@@ -16,7 +16,7 @@
 /*
  * Metadata version.
  */
-#define DMZ_META_VER	1
+#define DMZ_META_VER	2
 
 /*
  * On-disk super block magic.
@@ -69,8 +69,17 @@ struct dmz_super {
 	/* Checksum */
 	__le32		crc;			/*  48 */
 
+	/* DM-Zoned label */
+	u8		dmz_label[32];		/*  80 */
+
+	/* DM-Zoned UUID */
+	u8		dmz_uuid[16];		/*  96 */
+
+	/* Device UUID */
+	u8		dev_uuid[16];		/* 112 */
+
 	/* Padding to full 512B sector */
-	u8		reserved[464];		/* 512 */
+	u8		reserved[400];		/* 512 */
 };
 
 /*
@@ -122,8 +131,10 @@ enum {
  */
 struct dmz_sb {
 	sector_t		block;
+	struct dmz_dev		*dev;
 	struct dmz_mblock	*mblk;
 	struct dmz_super	*sb;
+	struct dm_zone		*zone;
 };
 
 /*
@@ -131,28 +142,41 @@ struct dmz_sb {
  */
 struct dmz_metadata {
 	struct dmz_dev		*dev;
+	unsigned int		nr_devs;
+
+	char			devname[BDEVNAME_SIZE];
+	char			label[BDEVNAME_SIZE];
+	uuid_t			uuid;
 
 	sector_t		zone_bitmap_size;
 	unsigned int		zone_nr_bitmap_blocks;
 	unsigned int		zone_bits_per_mblk;
 
+	sector_t		zone_nr_blocks;
+	sector_t		zone_nr_blocks_shift;
+
+	sector_t		zone_nr_sectors;
+	sector_t		zone_nr_sectors_shift;
+
 	unsigned int		nr_bitmap_blocks;
 	unsigned int		nr_map_blocks;
 
+	unsigned int		nr_zones;
 	unsigned int		nr_useable_zones;
 	unsigned int		nr_meta_blocks;
 	unsigned int		nr_meta_zones;
 	unsigned int		nr_data_zones;
+	unsigned int		nr_cache_zones;
 	unsigned int		nr_rnd_zones;
 	unsigned int		nr_reserved_seq;
 	unsigned int		nr_chunks;
 
 	/* Zone information array */
-	struct dm_zone		*zones;
+	struct xarray		zones;
 
-	struct dm_zone		*sb_zone;
 	struct dmz_sb		sb[2];
 	unsigned int		mblk_primary;
+	unsigned int		sb_version;
 	u64			sb_gen;
 	unsigned int		min_nr_mblks;
 	unsigned int		max_nr_mblks;
@@ -168,15 +192,11 @@ struct dmz_metadata {
 	/* Zone allocation management */
 	struct mutex		map_lock;
 	struct dmz_mblock	**map_mblk;
-	unsigned int		nr_rnd;
-	atomic_t		unmap_nr_rnd;
-	struct list_head	unmap_rnd_list;
-	struct list_head	map_rnd_list;
 
-	unsigned int		nr_seq;
-	atomic_t		unmap_nr_seq;
-	struct list_head	unmap_seq_list;
-	struct list_head	map_seq_list;
+	unsigned int		nr_cache;
+	atomic_t		unmap_nr_cache;
+	struct list_head	unmap_cache_list;
+	struct list_head	map_cache_list;
 
 	atomic_t		nr_reserved_seq_zones;
 	struct list_head	reserved_seq_zones_list;
@@ -184,22 +204,65 @@ struct dmz_metadata {
 	wait_queue_head_t	free_wq;
 };
 
+#define dmz_zmd_info(zmd, format, args...)	\
+	DMINFO("(%s): " format, (zmd)->label, ## args)
+
+#define dmz_zmd_err(zmd, format, args...)	\
+	DMERR("(%s): " format, (zmd)->label, ## args)
+
+#define dmz_zmd_warn(zmd, format, args...)	\
+	DMWARN("(%s): " format, (zmd)->label, ## args)
+
+#define dmz_zmd_debug(zmd, format, args...)	\
+	DMDEBUG("(%s): " format, (zmd)->label, ## args)
 /*
  * Various accessors
  */
-unsigned int dmz_id(struct dmz_metadata *zmd, struct dm_zone *zone)
+static unsigned int dmz_dev_zone_id(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
-	return ((unsigned int)(zone - zmd->zones));
+	if (WARN_ON(!zone))
+		return 0;
+
+	return zone->id - zone->dev->zone_offset;
 }
 
 sector_t dmz_start_sect(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
-	return (sector_t)dmz_id(zmd, zone) << zmd->dev->zone_nr_sectors_shift;
+	unsigned int zone_id = dmz_dev_zone_id(zmd, zone);
+
+	return (sector_t)zone_id << zmd->zone_nr_sectors_shift;
 }
 
 sector_t dmz_start_block(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
-	return (sector_t)dmz_id(zmd, zone) << zmd->dev->zone_nr_blocks_shift;
+	unsigned int zone_id = dmz_dev_zone_id(zmd, zone);
+
+	return (sector_t)zone_id << zmd->zone_nr_blocks_shift;
+}
+
+unsigned int dmz_zone_nr_blocks(struct dmz_metadata *zmd)
+{
+	return zmd->zone_nr_blocks;
+}
+
+unsigned int dmz_zone_nr_blocks_shift(struct dmz_metadata *zmd)
+{
+	return zmd->zone_nr_blocks_shift;
+}
+
+unsigned int dmz_zone_nr_sectors(struct dmz_metadata *zmd)
+{
+	return zmd->zone_nr_sectors;
+}
+
+unsigned int dmz_zone_nr_sectors_shift(struct dmz_metadata *zmd)
+{
+	return zmd->zone_nr_sectors_shift;
+}
+
+unsigned int dmz_nr_zones(struct dmz_metadata *zmd)
+{
+	return zmd->nr_zones;
 }
 
 unsigned int dmz_nr_chunks(struct dmz_metadata *zmd)
@@ -207,14 +270,88 @@ unsigned int dmz_nr_chunks(struct dmz_metadata *zmd)
 	return zmd->nr_chunks;
 }
 
-unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd)
+unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd, int idx)
 {
-	return zmd->nr_rnd;
+	return zmd->dev[idx].nr_rnd;
 }
 
-unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd)
+unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd, int idx)
 {
-	return atomic_read(&zmd->unmap_nr_rnd);
+	return atomic_read(&zmd->dev[idx].unmap_nr_rnd);
+}
+
+unsigned int dmz_nr_cache_zones(struct dmz_metadata *zmd)
+{
+	return zmd->nr_cache;
+}
+
+unsigned int dmz_nr_unmap_cache_zones(struct dmz_metadata *zmd)
+{
+	return atomic_read(&zmd->unmap_nr_cache);
+}
+
+unsigned int dmz_nr_seq_zones(struct dmz_metadata *zmd, int idx)
+{
+	return zmd->dev[idx].nr_seq;
+}
+
+unsigned int dmz_nr_unmap_seq_zones(struct dmz_metadata *zmd, int idx)
+{
+	return atomic_read(&zmd->dev[idx].unmap_nr_seq);
+}
+
+static struct dm_zone *dmz_get(struct dmz_metadata *zmd, unsigned int zone_id)
+{
+	return xa_load(&zmd->zones, zone_id);
+}
+
+static struct dm_zone *dmz_insert(struct dmz_metadata *zmd,
+				  unsigned int zone_id, struct dmz_dev *dev)
+{
+	struct dm_zone *zone = kzalloc(sizeof(struct dm_zone), GFP_KERNEL);
+
+	if (!zone)
+		return ERR_PTR(-ENOMEM);
+
+	if (xa_insert(&zmd->zones, zone_id, zone, GFP_KERNEL)) {
+		kfree(zone);
+		return ERR_PTR(-EBUSY);
+	}
+
+	INIT_LIST_HEAD(&zone->link);
+	atomic_set(&zone->refcount, 0);
+	zone->id = zone_id;
+	zone->chunk = DMZ_MAP_UNMAPPED;
+	zone->dev = dev;
+
+	return zone;
+}
+
+const char *dmz_metadata_label(struct dmz_metadata *zmd)
+{
+	return (const char *)zmd->label;
+}
+
+bool dmz_check_dev(struct dmz_metadata *zmd)
+{
+	unsigned int i;
+
+	for (i = 0; i < zmd->nr_devs; i++) {
+		if (!dmz_check_bdev(&zmd->dev[i]))
+			return false;
+	}
+	return true;
+}
+
+bool dmz_dev_is_dying(struct dmz_metadata *zmd)
+{
+	unsigned int i;
+
+	for (i = 0; i < zmd->nr_devs; i++) {
+		if (dmz_bdev_is_dying(&zmd->dev[i]))
+			return true;
+	}
+	return false;
 }
 
 /*
@@ -402,9 +539,10 @@ static struct dmz_mblock *dmz_get_mblock_slow(struct dmz_metadata *zmd,
 {
 	struct dmz_mblock *mblk, *m;
 	sector_t block = zmd->sb[zmd->mblk_primary].block + mblk_no;
+	struct dmz_dev *dev = zmd->sb[zmd->mblk_primary].dev;
 	struct bio *bio;
 
-	if (dmz_bdev_is_dying(zmd->dev))
+	if (dmz_bdev_is_dying(dev))
 		return ERR_PTR(-EIO);
 
 	/* Get a new block and a BIO to read it */
@@ -440,7 +578,7 @@ static struct dmz_mblock *dmz_get_mblock_slow(struct dmz_metadata *zmd,
 
 	/* Submit read BIO */
 	bio->bi_iter.bi_sector = dmz_blk2sect(block);
-	bio_set_dev(bio, zmd->dev->bdev);
+	bio_set_dev(bio, dev->bdev);
 	bio->bi_private = mblk;
 	bio->bi_end_io = dmz_mblock_bio_end_io;
 	bio_set_op_attrs(bio, REQ_OP_READ, REQ_META | REQ_PRIO);
@@ -537,6 +675,7 @@ static struct dmz_mblock *dmz_get_mblock(struct dmz_metadata *zmd,
 					 sector_t mblk_no)
 {
 	struct dmz_mblock *mblk;
+	struct dmz_dev *dev = zmd->sb[zmd->mblk_primary].dev;
 
 	/* Check rbtree */
 	spin_lock(&zmd->mblk_lock);
@@ -555,7 +694,7 @@ static struct dmz_mblock *dmz_get_mblock(struct dmz_metadata *zmd,
 		       TASK_UNINTERRUPTIBLE);
 	if (test_bit(DMZ_META_ERROR, &mblk->state)) {
 		dmz_release_mblock(zmd, mblk);
-		dmz_check_bdev(zmd->dev);
+		dmz_check_bdev(dev);
 		return ERR_PTR(-EIO);
 	}
 
@@ -579,10 +718,11 @@ static void dmz_dirty_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk)
 static int dmz_write_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk,
 			    unsigned int set)
 {
+	struct dmz_dev *dev = zmd->sb[set].dev;
 	sector_t block = zmd->sb[set].block + mblk->no;
 	struct bio *bio;
 
-	if (dmz_bdev_is_dying(zmd->dev))
+	if (dmz_bdev_is_dying(dev))
 		return -EIO;
 
 	bio = bio_alloc(GFP_NOIO, 1);
@@ -594,7 +734,7 @@ static int dmz_write_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk,
 	set_bit(DMZ_META_WRITING, &mblk->state);
 
 	bio->bi_iter.bi_sector = dmz_blk2sect(block);
-	bio_set_dev(bio, zmd->dev->bdev);
+	bio_set_dev(bio, dev->bdev);
 	bio->bi_private = mblk;
 	bio->bi_end_io = dmz_mblock_bio_end_io;
 	bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_META | REQ_PRIO);
@@ -607,13 +747,16 @@ static int dmz_write_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk,
 /*
  * Read/write a metadata block.
  */
-static int dmz_rdwr_block(struct dmz_metadata *zmd, int op, sector_t block,
-			  struct page *page)
+static int dmz_rdwr_block(struct dmz_dev *dev, int op,
+			  sector_t block, struct page *page)
 {
 	struct bio *bio;
 	int ret;
 
-	if (dmz_bdev_is_dying(zmd->dev))
+	if (WARN_ON(!dev))
+		return -EIO;
+
+	if (dmz_bdev_is_dying(dev))
 		return -EIO;
 
 	bio = bio_alloc(GFP_NOIO, 1);
@@ -621,14 +764,14 @@ static int dmz_rdwr_block(struct dmz_metadata *zmd, int op, sector_t block,
 		return -ENOMEM;
 
 	bio->bi_iter.bi_sector = dmz_blk2sect(block);
-	bio_set_dev(bio, zmd->dev->bdev);
+	bio_set_dev(bio, dev->bdev);
 	bio_set_op_attrs(bio, op, REQ_SYNC | REQ_META | REQ_PRIO);
 	bio_add_page(bio, page, DMZ_BLOCK_SIZE, 0);
 	ret = submit_bio_wait(bio);
 	bio_put(bio);
 
 	if (ret)
-		dmz_check_bdev(zmd->dev);
+		dmz_check_bdev(dev);
 	return ret;
 }
 
@@ -637,18 +780,32 @@ static int dmz_rdwr_block(struct dmz_metadata *zmd, int op, sector_t block,
  */
 static int dmz_write_sb(struct dmz_metadata *zmd, unsigned int set)
 {
-	sector_t block = zmd->sb[set].block;
 	struct dmz_mblock *mblk = zmd->sb[set].mblk;
 	struct dmz_super *sb = zmd->sb[set].sb;
+	struct dmz_dev *dev = zmd->sb[set].dev;
+	sector_t sb_block;
 	u64 sb_gen = zmd->sb_gen + 1;
 	int ret;
 
 	sb->magic = cpu_to_le32(DMZ_MAGIC);
-	sb->version = cpu_to_le32(DMZ_META_VER);
+
+	sb->version = cpu_to_le32(zmd->sb_version);
+	if (zmd->sb_version > 1) {
+		BUILD_BUG_ON(UUID_SIZE != 16);
+		export_uuid(sb->dmz_uuid, &zmd->uuid);
+		memcpy(sb->dmz_label, zmd->label, BDEVNAME_SIZE);
+		export_uuid(sb->dev_uuid, &dev->uuid);
+	}
 
 	sb->gen = cpu_to_le64(sb_gen);
 
-	sb->sb_block = cpu_to_le64(block);
+	/*
+	 * The metadata always references the absolute block address,
+	 * ie relative to the entire block range, not the per-device
+	 * block address.
+	 */
+	sb_block = zmd->sb[set].zone->id << zmd->zone_nr_blocks_shift;
+	sb->sb_block = cpu_to_le64(sb_block);
 	sb->nr_meta_blocks = cpu_to_le32(zmd->nr_meta_blocks);
 	sb->nr_reserved_seq = cpu_to_le32(zmd->nr_reserved_seq);
 	sb->nr_chunks = cpu_to_le32(zmd->nr_chunks);
@@ -659,9 +816,10 @@ static int dmz_write_sb(struct dmz_metadata *zmd, unsigned int set)
 	sb->crc = 0;
 	sb->crc = cpu_to_le32(crc32_le(sb_gen, (unsigned char *)sb, DMZ_BLOCK_SIZE));
 
-	ret = dmz_rdwr_block(zmd, REQ_OP_WRITE, block, mblk->page);
+	ret = dmz_rdwr_block(dev, REQ_OP_WRITE, zmd->sb[set].block,
+			     mblk->page);
 	if (ret == 0)
-		ret = blkdev_issue_flush(zmd->dev->bdev, GFP_NOIO);
+		ret = blkdev_issue_flush(dev->bdev, GFP_NOIO);
 
 	return ret;
 }
@@ -674,6 +832,7 @@ static int dmz_write_dirty_mblocks(struct dmz_metadata *zmd,
 				   unsigned int set)
 {
 	struct dmz_mblock *mblk;
+	struct dmz_dev *dev = zmd->sb[set].dev;
 	struct blk_plug plug;
 	int ret = 0, nr_mblks_submitted = 0;
 
@@ -695,7 +854,7 @@ static int dmz_write_dirty_mblocks(struct dmz_metadata *zmd,
 			       TASK_UNINTERRUPTIBLE);
 		if (test_bit(DMZ_META_ERROR, &mblk->state)) {
 			clear_bit(DMZ_META_ERROR, &mblk->state);
-			dmz_check_bdev(zmd->dev);
+			dmz_check_bdev(dev);
 			ret = -EIO;
 		}
 		nr_mblks_submitted--;
@@ -703,7 +862,7 @@ static int dmz_write_dirty_mblocks(struct dmz_metadata *zmd,
 
 	/* Flush drive cache (this will also sync data) */
 	if (ret == 0)
-		ret = blkdev_issue_flush(zmd->dev->bdev, GFP_NOIO);
+		ret = blkdev_issue_flush(dev->bdev, GFP_NOIO);
 
 	return ret;
 }
@@ -740,6 +899,7 @@ int dmz_flush_metadata(struct dmz_metadata *zmd)
 {
 	struct dmz_mblock *mblk;
 	struct list_head write_list;
+	struct dmz_dev *dev;
 	int ret;
 
 	if (WARN_ON(!zmd))
@@ -753,6 +913,7 @@ int dmz_flush_metadata(struct dmz_metadata *zmd)
 	 * from modifying metadata.
 	 */
 	down_write(&zmd->mblk_sem);
+	dev = zmd->sb[zmd->mblk_primary].dev;
 
 	/*
 	 * This is called from the target flush work and reclaim work.
@@ -760,7 +921,7 @@ int dmz_flush_metadata(struct dmz_metadata *zmd)
 	 */
 	dmz_lock_flush(zmd);
 
-	if (dmz_bdev_is_dying(zmd->dev)) {
+	if (dmz_bdev_is_dying(dev)) {
 		ret = -EIO;
 		goto out;
 	}
@@ -772,7 +933,7 @@ int dmz_flush_metadata(struct dmz_metadata *zmd)
 
 	/* If there are no dirty metadata blocks, just flush the device cache */
 	if (list_empty(&write_list)) {
-		ret = blkdev_issue_flush(zmd->dev->bdev, GFP_NOIO);
+		ret = blkdev_issue_flush(dev->bdev, GFP_NOIO);
 		goto err;
 	}
 
@@ -821,7 +982,7 @@ err:
 		list_splice(&write_list, &zmd->mblk_dirty_list);
 		spin_unlock(&zmd->mblk_lock);
 	}
-	if (!dmz_check_bdev(zmd->dev))
+	if (!dmz_check_bdev(dev))
 		ret = -EIO;
 	goto out;
 }
@@ -829,12 +990,31 @@ err:
 /*
  * Check super block.
  */
-static int dmz_check_sb(struct dmz_metadata *zmd, struct dmz_super *sb)
+static int dmz_check_sb(struct dmz_metadata *zmd, struct dmz_sb *dsb,
+			bool tertiary)
 {
+	struct dmz_super *sb = dsb->sb;
+	struct dmz_dev *dev = dsb->dev;
 	unsigned int nr_meta_zones, nr_data_zones;
-	struct dmz_dev *dev = zmd->dev;
 	u32 crc, stored_crc;
-	u64 gen;
+	u64 gen, sb_block;
+
+	if (le32_to_cpu(sb->magic) != DMZ_MAGIC) {
+		dmz_dev_err(dev, "Invalid meta magic (needed 0x%08x, got 0x%08x)",
+			    DMZ_MAGIC, le32_to_cpu(sb->magic));
+		return -ENXIO;
+	}
+
+	zmd->sb_version = le32_to_cpu(sb->version);
+	if (zmd->sb_version > DMZ_META_VER) {
+		dmz_dev_err(dev, "Invalid meta version (needed %d, got %d)",
+			    DMZ_META_VER, zmd->sb_version);
+		return -EINVAL;
+	}
+	if (zmd->sb_version < 2 && tertiary) {
+		dmz_dev_err(dev, "Tertiary superblocks are not supported");
+		return -EINVAL;
+	}
 
 	gen = le64_to_cpu(sb->gen);
 	stored_crc = le32_to_cpu(sb->crc);
@@ -846,20 +1026,57 @@ static int dmz_check_sb(struct dmz_metadata *zmd, struct dmz_super *sb)
 		return -ENXIO;
 	}
 
-	if (le32_to_cpu(sb->magic) != DMZ_MAGIC) {
-		dmz_dev_err(dev, "Invalid meta magic (needed 0x%08x, got 0x%08x)",
-			    DMZ_MAGIC, le32_to_cpu(sb->magic));
-		return -ENXIO;
-	}
+	sb_block = le64_to_cpu(sb->sb_block);
+	if (sb_block != (u64)dsb->zone->id << zmd->zone_nr_blocks_shift ) {
+		dmz_dev_err(dev, "Invalid superblock position "
+			    "(is %llu expected %llu)",
+			    sb_block,
+			    (u64)dsb->zone->id << zmd->zone_nr_blocks_shift);
+		return -EINVAL;
+	}
+	if (zmd->sb_version > 1) {
+		uuid_t sb_uuid;
+
+		import_uuid(&sb_uuid, sb->dmz_uuid);
+		if (uuid_is_null(&sb_uuid)) {
+			dmz_dev_err(dev, "NULL DM-Zoned uuid");
+			return -ENXIO;
+		} else if (uuid_is_null(&zmd->uuid)) {
+			uuid_copy(&zmd->uuid, &sb_uuid);
+		} else if (!uuid_equal(&zmd->uuid, &sb_uuid)) {
+			dmz_dev_err(dev, "mismatching DM-Zoned uuid, "
+				    "is %pUl expected %pUl",
+				    &sb_uuid, &zmd->uuid);
+			return -ENXIO;
+		}
+		if (!strlen(zmd->label))
+			memcpy(zmd->label, sb->dmz_label, BDEVNAME_SIZE);
+		else if (memcmp(zmd->label, sb->dmz_label, BDEVNAME_SIZE)) {
+			dmz_dev_err(dev, "mismatching DM-Zoned label, "
+				    "is %s expected %s",
+				    sb->dmz_label, zmd->label);
+			return -ENXIO;
+		}
+		import_uuid(&dev->uuid, sb->dev_uuid);
+		if (uuid_is_null(&dev->uuid)) {
+			dmz_dev_err(dev, "NULL device uuid");
+			return -ENXIO;
+		}
 
-	if (le32_to_cpu(sb->version) != DMZ_META_VER) {
-		dmz_dev_err(dev, "Invalid meta version (needed %d, got %d)",
-			    DMZ_META_VER, le32_to_cpu(sb->version));
-		return -ENXIO;
+		if (tertiary) {
+			/*
+			 * Generation number should be 0, but it doesn't
+			 * really matter if it isn't.
+			 */
+			if (gen != 0)
+				dmz_dev_warn(dev, "Invalid generation %llu",
+					    gen);
+			return 0;
+		}
 	}
 
-	nr_meta_zones = (le32_to_cpu(sb->nr_meta_blocks) + dev->zone_nr_blocks - 1)
-		>> dev->zone_nr_blocks_shift;
+	nr_meta_zones = (le32_to_cpu(sb->nr_meta_blocks) + zmd->zone_nr_blocks - 1)
+		>> zmd->zone_nr_blocks_shift;
 	if (!nr_meta_zones ||
 	    nr_meta_zones >= zmd->nr_rnd_zones) {
 		dmz_dev_err(dev, "Invalid number of metadata blocks");
@@ -895,10 +1112,13 @@ static int dmz_check_sb(struct dmz_metadata *zmd, struct dmz_super *sb)
 /*
  * Read the first or second super block from disk.
  */
-static int dmz_read_sb(struct dmz_metadata *zmd, unsigned int set)
+static int dmz_read_sb(struct dmz_metadata *zmd, struct dmz_sb *sb, int set)
 {
-	return dmz_rdwr_block(zmd, REQ_OP_READ, zmd->sb[set].block,
-			      zmd->sb[set].mblk->page);
+	dmz_zmd_debug(zmd, "read superblock set %d dev %s block %llu",
+		      set, sb->dev->name, sb->block);
+
+	return dmz_rdwr_block(sb->dev, REQ_OP_READ,
+			      sb->block, sb->mblk->page);
 }
 
 /*
@@ -908,8 +1128,9 @@ static int dmz_read_sb(struct dmz_metadata *zmd, unsigned int set)
  */
 static int dmz_lookup_secondary_sb(struct dmz_metadata *zmd)
 {
-	unsigned int zone_nr_blocks = zmd->dev->zone_nr_blocks;
+	unsigned int zone_nr_blocks = zmd->zone_nr_blocks;
 	struct dmz_mblock *mblk;
+	unsigned int zone_id = zmd->sb[0].zone->id;
 	int i;
 
 	/* Allocate a block */
@@ -922,24 +1143,29 @@ static int dmz_lookup_secondary_sb(struct dmz_metadata *zmd)
 
 	/* Bad first super block: search for the second one */
 	zmd->sb[1].block = zmd->sb[0].block + zone_nr_blocks;
-	for (i = 0; i < zmd->nr_rnd_zones - 1; i++) {
-		if (dmz_read_sb(zmd, 1) != 0)
+	zmd->sb[1].zone = dmz_get(zmd, zone_id + 1);
+	zmd->sb[1].dev = zmd->sb[0].dev;
+	for (i = 1; i < zmd->nr_rnd_zones; i++) {
+		if (dmz_read_sb(zmd, &zmd->sb[1], 1) != 0)
 			break;
 		if (le32_to_cpu(zmd->sb[1].sb->magic) == DMZ_MAGIC)
 			return 0;
 		zmd->sb[1].block += zone_nr_blocks;
+		zmd->sb[1].zone = dmz_get(zmd, zone_id + i);
 	}
 
 	dmz_free_mblock(zmd, mblk);
 	zmd->sb[1].mblk = NULL;
+	zmd->sb[1].zone = NULL;
+	zmd->sb[1].dev = NULL;
 
 	return -EIO;
 }
 
 /*
- * Read the first or second super block from disk.
+ * Read a super block from disk.
  */
-static int dmz_get_sb(struct dmz_metadata *zmd, unsigned int set)
+static int dmz_get_sb(struct dmz_metadata *zmd, struct dmz_sb *sb, int set)
 {
 	struct dmz_mblock *mblk;
 	int ret;
@@ -949,14 +1175,14 @@ static int dmz_get_sb(struct dmz_metadata *zmd, unsigned int set)
 	if (!mblk)
 		return -ENOMEM;
 
-	zmd->sb[set].mblk = mblk;
-	zmd->sb[set].sb = mblk->data;
+	sb->mblk = mblk;
+	sb->sb = mblk->data;
 
 	/* Read super block */
-	ret = dmz_read_sb(zmd, set);
+	ret = dmz_read_sb(zmd, sb, set);
 	if (ret) {
 		dmz_free_mblock(zmd, mblk);
-		zmd->sb[set].mblk = NULL;
+		sb->mblk = NULL;
 		return ret;
 	}
 
@@ -972,14 +1198,13 @@ static int dmz_recover_mblocks(struct dmz_metadata *zmd, unsigned int dst_set)
 	struct page *page;
 	int i, ret;
 
-	dmz_dev_warn(zmd->dev, "Metadata set %u invalid: recovering", dst_set);
+	dmz_dev_warn(zmd->sb[dst_set].dev,
+		     "Metadata set %u invalid: recovering", dst_set);
 
 	if (dst_set == 0)
-		zmd->sb[0].block = dmz_start_block(zmd, zmd->sb_zone);
-	else {
-		zmd->sb[1].block = zmd->sb[0].block +
-			(zmd->nr_meta_zones << zmd->dev->zone_nr_blocks_shift);
-	}
+		zmd->sb[0].block = dmz_start_block(zmd, zmd->sb[0].zone);
+	else
+		zmd->sb[1].block = dmz_start_block(zmd, zmd->sb[1].zone);
 
 	page = alloc_page(GFP_NOIO);
 	if (!page)
@@ -987,11 +1212,11 @@ static int dmz_recover_mblocks(struct dmz_metadata *zmd, unsigned int dst_set)
 
 	/* Copy metadata blocks */
 	for (i = 1; i < zmd->nr_meta_blocks; i++) {
-		ret = dmz_rdwr_block(zmd, REQ_OP_READ,
+		ret = dmz_rdwr_block(zmd->sb[src_set].dev, REQ_OP_READ,
 				     zmd->sb[src_set].block + i, page);
 		if (ret)
 			goto out;
-		ret = dmz_rdwr_block(zmd, REQ_OP_WRITE,
+		ret = dmz_rdwr_block(zmd->sb[dst_set].dev, REQ_OP_WRITE,
 				     zmd->sb[dst_set].block + i, page);
 		if (ret)
 			goto out;
@@ -1023,53 +1248,73 @@ static int dmz_load_sb(struct dmz_metadata *zmd)
 	u64 sb_gen[2] = {0, 0};
 	int ret;
 
+	if (!zmd->sb[0].zone) {
+		dmz_zmd_err(zmd, "Primary super block zone not set");
+		return -ENXIO;
+	}
+
 	/* Read and check the primary super block */
-	zmd->sb[0].block = dmz_start_block(zmd, zmd->sb_zone);
-	ret = dmz_get_sb(zmd, 0);
+	zmd->sb[0].block = dmz_start_block(zmd, zmd->sb[0].zone);
+	zmd->sb[0].dev = zmd->sb[0].zone->dev;
+	ret = dmz_get_sb(zmd, &zmd->sb[0], 0);
 	if (ret) {
-		dmz_dev_err(zmd->dev, "Read primary super block failed");
+		dmz_dev_err(zmd->sb[0].dev, "Read primary super block failed");
 		return ret;
 	}
 
-	ret = dmz_check_sb(zmd, zmd->sb[0].sb);
+	ret = dmz_check_sb(zmd, &zmd->sb[0], false);
 
 	/* Read and check secondary super block */
 	if (ret == 0) {
 		sb_good[0] = true;
-		zmd->sb[1].block = zmd->sb[0].block +
-			(zmd->nr_meta_zones << zmd->dev->zone_nr_blocks_shift);
-		ret = dmz_get_sb(zmd, 1);
+		if (!zmd->sb[1].zone) {
+			unsigned int zone_id =
+				zmd->sb[0].zone->id + zmd->nr_meta_zones;
+
+			zmd->sb[1].zone = dmz_get(zmd, zone_id);
+		}
+		zmd->sb[1].block = dmz_start_block(zmd, zmd->sb[1].zone);
+		zmd->sb[1].dev = zmd->sb[0].dev;
+		ret = dmz_get_sb(zmd, &zmd->sb[1], 1);
 	} else
 		ret = dmz_lookup_secondary_sb(zmd);
 
 	if (ret) {
-		dmz_dev_err(zmd->dev, "Read secondary super block failed");
+		dmz_dev_err(zmd->sb[1].dev, "Read secondary super block failed");
 		return ret;
 	}
 
-	ret = dmz_check_sb(zmd, zmd->sb[1].sb);
+	ret = dmz_check_sb(zmd, &zmd->sb[1], false);
 	if (ret == 0)
 		sb_good[1] = true;
 
 	/* Use highest generation sb first */
 	if (!sb_good[0] && !sb_good[1]) {
-		dmz_dev_err(zmd->dev, "No valid super block found");
+		dmz_zmd_err(zmd, "No valid super block found");
 		return -EIO;
 	}
 
 	if (sb_good[0])
 		sb_gen[0] = le64_to_cpu(zmd->sb[0].sb->gen);
-	else
+	else {
 		ret = dmz_recover_mblocks(zmd, 0);
+		if (ret) {
+			dmz_dev_err(zmd->sb[0].dev,
+				    "Recovery of superblock 0 failed");
+			return -EIO;
+		}
+	}
 
 	if (sb_good[1])
 		sb_gen[1] = le64_to_cpu(zmd->sb[1].sb->gen);
-	else
+	else {
 		ret = dmz_recover_mblocks(zmd, 1);
 
-	if (ret) {
-		dmz_dev_err(zmd->dev, "Recovery failed");
-		return -EIO;
+		if (ret) {
+			dmz_dev_err(zmd->sb[1].dev,
+				    "Recovery of superblock 1 failed");
+			return -EIO;
+		}
 	}
 
 	if (sb_gen[0] >= sb_gen[1]) {
@@ -1080,32 +1325,70 @@ static int dmz_load_sb(struct dmz_metadata *zmd)
 		zmd->mblk_primary = 1;
 	}
 
-	dmz_dev_debug(zmd->dev, "Using super block %u (gen %llu)",
+	dmz_dev_debug(zmd->sb[zmd->mblk_primary].dev,
+		      "Using super block %u (gen %llu)",
 		      zmd->mblk_primary, zmd->sb_gen);
 
-	return 0;
+	if (zmd->sb_version > 1) {
+		int i;
+		struct dmz_sb *sb;
+
+		sb = kzalloc(sizeof(struct dmz_sb), GFP_KERNEL);
+		if (!sb)
+			return -ENOMEM;
+		for (i = 1; i < zmd->nr_devs; i++) {
+			sb->block = 0;
+			sb->zone = dmz_get(zmd, zmd->dev[i].zone_offset);
+			sb->dev = &zmd->dev[i];
+			if (!dmz_is_meta(sb->zone)) {
+				dmz_dev_err(sb->dev,
+					    "Tertiary super block zone %u not marked as metadata zone",
+					    sb->zone->id);
+				ret = -EINVAL;
+				goto out_kfree;
+			}
+			ret = dmz_get_sb(zmd, sb, i + 1);
+			if (ret) {
+				dmz_dev_err(sb->dev,
+					    "Read tertiary super block failed");
+				dmz_free_mblock(zmd, sb->mblk);
+				goto out_kfree;
+			}
+			ret = dmz_check_sb(zmd, sb, true);
+			dmz_free_mblock(zmd, sb->mblk);
+			if (ret == -EINVAL)
+				goto out_kfree;
+		}
+	out_kfree:
+		kfree(sb);
+	}
+	return ret;
 }
 
 /*
  * Initialize a zone descriptor.
  */
-static int dmz_init_zone(struct blk_zone *blkz, unsigned int idx, void *data)
+static int dmz_init_zone(struct blk_zone *blkz, unsigned int num, void *data)
 {
-	struct dmz_metadata *zmd = data;
-	struct dm_zone *zone = &zmd->zones[idx];
-	struct dmz_dev *dev = zmd->dev;
+	struct dmz_dev *dev = data;
+	struct dmz_metadata *zmd = dev->metadata;
+	int idx = num + dev->zone_offset;
+	struct dm_zone *zone;
+
+	zone = dmz_insert(zmd, idx, dev);
+	if (IS_ERR(zone))
+		return PTR_ERR(zone);
 
-	/* Ignore the eventual last runt (smaller) zone */
-	if (blkz->len != dev->zone_nr_sectors) {
-		if (blkz->start + blkz->len == dev->capacity)
+	if (blkz->len != zmd->zone_nr_sectors) {
+		if (zmd->sb_version > 1) {
+			/* Ignore the eventual runt (smaller) zone */
+			set_bit(DMZ_OFFLINE, &zone->flags);
+			return 0;
+		} else if (blkz->start + blkz->len == dev->capacity)
 			return 0;
 		return -ENXIO;
 	}
 
-	INIT_LIST_HEAD(&zone->link);
-	atomic_set(&zone->refcount, 0);
-	zone->chunk = DMZ_MAP_UNMAPPED;
-
 	switch (blkz->type) {
 	case BLK_ZONE_TYPE_CONVENTIONAL:
 		set_bit(DMZ_RND, &zone->flags);
@@ -1131,13 +1414,45 @@ static int dmz_init_zone(struct blk_zone *blkz, unsigned int idx, void *data)
 		zmd->nr_useable_zones++;
 		if (dmz_is_rnd(zone)) {
 			zmd->nr_rnd_zones++;
-			if (!zmd->sb_zone) {
-				/* Super block zone */
-				zmd->sb_zone = zone;
+			if (zmd->nr_devs == 1 && !zmd->sb[0].zone) {
+				/* Primary super block zone */
+				zmd->sb[0].zone = zone;
 			}
 		}
+		if (zmd->nr_devs > 1 && num == 0) {
+			/*
+			 * Tertiary superblock zones are always at the
+			 * start of the zoned devices, so mark them
+			 * as metadata zone.
+			 */
+			set_bit(DMZ_META, &zone->flags);
+		}
 	}
+	return 0;
+}
+
+static int dmz_emulate_zones(struct dmz_metadata *zmd, struct dmz_dev *dev)
+{
+	int idx;
+	sector_t zone_offset = 0;
 
+	for(idx = 0; idx < dev->nr_zones; idx++) {
+		struct dm_zone *zone;
+
+		zone = dmz_insert(zmd, idx, dev);
+		if (IS_ERR(zone))
+			return PTR_ERR(zone);
+		set_bit(DMZ_CACHE, &zone->flags);
+		zone->wp_block = 0;
+		zmd->nr_cache_zones++;
+		zmd->nr_useable_zones++;
+		if (dev->capacity - zone_offset < zmd->zone_nr_sectors) {
+			/* Disable runt zone */
+			set_bit(DMZ_OFFLINE, &zone->flags);
+			break;
+		}
+		zone_offset += zmd->zone_nr_sectors;
+	}
 	return 0;
 }
 
@@ -1146,8 +1461,15 @@ static int dmz_init_zone(struct blk_zone *blkz, unsigned int idx, void *data)
  */
 static void dmz_drop_zones(struct dmz_metadata *zmd)
 {
-	kfree(zmd->zones);
-	zmd->zones = NULL;
+	int idx;
+
+	for(idx = 0; idx < zmd->nr_zones; idx++) {
+		struct dm_zone *zone = xa_load(&zmd->zones, idx);
+
+		kfree(zone);
+		xa_erase(&zmd->zones, idx);
+	}
+	xa_destroy(&zmd->zones);
 }
 
 /*
@@ -1156,32 +1478,87 @@ static void dmz_drop_zones(struct dmz_metadata *zmd)
  */
 static int dmz_init_zones(struct dmz_metadata *zmd)
 {
-	struct dmz_dev *dev = zmd->dev;
-	int ret;
+	int i, ret;
+	struct dmz_dev *zoned_dev = &zmd->dev[0];
 
 	/* Init */
-	zmd->zone_bitmap_size = dev->zone_nr_blocks >> 3;
+	zmd->zone_nr_sectors = zmd->dev[0].zone_nr_sectors;
+	zmd->zone_nr_sectors_shift = ilog2(zmd->zone_nr_sectors);
+	zmd->zone_nr_blocks = dmz_sect2blk(zmd->zone_nr_sectors);
+	zmd->zone_nr_blocks_shift = ilog2(zmd->zone_nr_blocks);
+	zmd->zone_bitmap_size = zmd->zone_nr_blocks >> 3;
 	zmd->zone_nr_bitmap_blocks =
 		max_t(sector_t, 1, zmd->zone_bitmap_size >> DMZ_BLOCK_SHIFT);
-	zmd->zone_bits_per_mblk = min_t(sector_t, dev->zone_nr_blocks,
+	zmd->zone_bits_per_mblk = min_t(sector_t, zmd->zone_nr_blocks,
 					DMZ_BLOCK_SIZE_BITS);
 
 	/* Allocate zone array */
-	zmd->zones = kcalloc(dev->nr_zones, sizeof(struct dm_zone), GFP_KERNEL);
-	if (!zmd->zones)
-		return -ENOMEM;
+	zmd->nr_zones = 0;
+	for (i = 0; i < zmd->nr_devs; i++) {
+		struct dmz_dev *dev = &zmd->dev[i];
+
+		dev->metadata = zmd;
+		zmd->nr_zones += dev->nr_zones;
+
+		atomic_set(&dev->unmap_nr_rnd, 0);
+		INIT_LIST_HEAD(&dev->unmap_rnd_list);
+		INIT_LIST_HEAD(&dev->map_rnd_list);
+
+		atomic_set(&dev->unmap_nr_seq, 0);
+		INIT_LIST_HEAD(&dev->unmap_seq_list);
+		INIT_LIST_HEAD(&dev->map_seq_list);
+	}
+
+	if (!zmd->nr_zones) {
+		DMERR("(%s): No zones found", zmd->devname);
+		return -ENXIO;
+	}
+	xa_init(&zmd->zones);
+
+	DMDEBUG("(%s): Using %zu B for zone information",
+		zmd->devname, sizeof(struct dm_zone) * zmd->nr_zones);
 
-	dmz_dev_info(dev, "Using %zu B for zone information",
-		     sizeof(struct dm_zone) * dev->nr_zones);
+	if (zmd->nr_devs > 1) {
+		ret = dmz_emulate_zones(zmd, &zmd->dev[0]);
+		if (ret < 0) {
+			DMDEBUG("(%s): Failed to emulate zones, error %d",
+				zmd->devname, ret);
+			dmz_drop_zones(zmd);
+			return ret;
+		}
+
+		/*
+		 * Primary superblock zone is always at zone 0 when multiple
+		 * drives are present.
+		 */
+		zmd->sb[0].zone = dmz_get(zmd, 0);
+
+		for (i = 1; i < zmd->nr_devs; i++) {
+			zoned_dev = &zmd->dev[i];
+
+			ret = blkdev_report_zones(zoned_dev->bdev, 0,
+						  BLK_ALL_ZONES,
+						  dmz_init_zone, zoned_dev);
+			if (ret < 0) {
+				DMDEBUG("(%s): Failed to report zones, error %d",
+					zmd->devname, ret);
+				dmz_drop_zones(zmd);
+				return ret;
+			}
+		}
+		return 0;
+	}
 
 	/*
 	 * Get zone information and initialize zone descriptors.  At the same
 	 * time, determine where the super block should be: first block of the
 	 * first randomly writable zone.
 	 */
-	ret = blkdev_report_zones(dev->bdev, 0, BLK_ALL_ZONES, dmz_init_zone,
-				  zmd);
+	ret = blkdev_report_zones(zoned_dev->bdev, 0, BLK_ALL_ZONES,
+				  dmz_init_zone, zoned_dev);
 	if (ret < 0) {
+		DMDEBUG("(%s): Failed to report zones, error %d",
+			zmd->devname, ret);
 		dmz_drop_zones(zmd);
 		return ret;
 	}
@@ -1213,9 +1590,13 @@ static int dmz_update_zone_cb(struct blk_zone *blkz, unsigned int idx,
  */
 static int dmz_update_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
+	struct dmz_dev *dev = zone->dev;
 	unsigned int noio_flag;
 	int ret;
 
+	if (dev->flags & DMZ_BDEV_REGULAR)
+		return 0;
+
 	/*
 	 * Get zone information from disk. Since blkdev_report_zones() uses
 	 * GFP_KERNEL by default for memory allocations, set the per-task
@@ -1223,16 +1604,16 @@ static int dmz_update_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 	 * GFP_NOIO was specified.
 	 */
 	noio_flag = memalloc_noio_save();
-	ret = blkdev_report_zones(zmd->dev->bdev, dmz_start_sect(zmd, zone), 1,
+	ret = blkdev_report_zones(dev->bdev, dmz_start_sect(zmd, zone), 1,
 				  dmz_update_zone_cb, zone);
 	memalloc_noio_restore(noio_flag);
 
 	if (ret == 0)
 		ret = -EIO;
 	if (ret < 0) {
-		dmz_dev_err(zmd->dev, "Get zone %u report failed",
-			    dmz_id(zmd, zone));
-		dmz_check_bdev(zmd->dev);
+		dmz_dev_err(dev, "Get zone %u report failed",
+			    zone->id);
+		dmz_check_bdev(dev);
 		return ret;
 	}
 
@@ -1246,6 +1627,7 @@ static int dmz_update_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 static int dmz_handle_seq_write_err(struct dmz_metadata *zmd,
 				    struct dm_zone *zone)
 {
+	struct dmz_dev *dev = zone->dev;
 	unsigned int wp = 0;
 	int ret;
 
@@ -1254,8 +1636,8 @@ static int dmz_handle_seq_write_err(struct dmz_metadata *zmd,
 	if (ret)
 		return ret;
 
-	dmz_dev_warn(zmd->dev, "Processing zone %u write error (zone wp %u/%u)",
-		     dmz_id(zmd, zone), zone->wp_block, wp);
+	dmz_dev_warn(dev, "Processing zone %u write error (zone wp %u/%u)",
+		     zone->id, zone->wp_block, wp);
 
 	if (zone->wp_block < wp) {
 		dmz_invalidate_blocks(zmd, zone, zone->wp_block,
@@ -1265,11 +1647,6 @@ static int dmz_handle_seq_write_err(struct dmz_metadata *zmd,
 	return 0;
 }
 
-static struct dm_zone *dmz_get(struct dmz_metadata *zmd, unsigned int zone_id)
-{
-	return &zmd->zones[zone_id];
-}
-
 /*
  * Reset a zone write pointer.
  */
@@ -1287,14 +1664,14 @@ static int dmz_reset_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 		return 0;
 
 	if (!dmz_is_empty(zone) || dmz_seq_write_err(zone)) {
-		struct dmz_dev *dev = zmd->dev;
+		struct dmz_dev *dev = zone->dev;
 
 		ret = blkdev_zone_mgmt(dev->bdev, REQ_OP_ZONE_RESET,
 				       dmz_start_sect(zmd, zone),
-				       dev->zone_nr_sectors, GFP_NOIO);
+				       zmd->zone_nr_sectors, GFP_NOIO);
 		if (ret) {
 			dmz_dev_err(dev, "Reset zone %u failed %d",
-				    dmz_id(zmd, zone), ret);
+				    zone->id, ret);
 			return ret;
 		}
 	}
@@ -1313,7 +1690,6 @@ static void dmz_get_zone_weight(struct dmz_metadata *zmd, struct dm_zone *zone);
  */
 static int dmz_load_mapping(struct dmz_metadata *zmd)
 {
-	struct dmz_dev *dev = zmd->dev;
 	struct dm_zone *dzone, *bzone;
 	struct dmz_mblock *dmap_mblk = NULL;
 	struct dmz_map *dmap;
@@ -1345,36 +1721,48 @@ static int dmz_load_mapping(struct dmz_metadata *zmd)
 		if (dzone_id == DMZ_MAP_UNMAPPED)
 			goto next;
 
-		if (dzone_id >= dev->nr_zones) {
-			dmz_dev_err(dev, "Chunk %u mapping: invalid data zone ID %u",
+		if (dzone_id >= zmd->nr_zones) {
+			dmz_zmd_err(zmd, "Chunk %u mapping: invalid data zone ID %u",
 				    chunk, dzone_id);
 			return -EIO;
 		}
 
 		dzone = dmz_get(zmd, dzone_id);
+		if (!dzone) {
+			dmz_zmd_err(zmd, "Chunk %u mapping: data zone %u not present",
+				    chunk, dzone_id);
+			return -EIO;
+		}
 		set_bit(DMZ_DATA, &dzone->flags);
 		dzone->chunk = chunk;
 		dmz_get_zone_weight(zmd, dzone);
 
-		if (dmz_is_rnd(dzone))
-			list_add_tail(&dzone->link, &zmd->map_rnd_list);
+		if (dmz_is_cache(dzone))
+			list_add_tail(&dzone->link, &zmd->map_cache_list);
+		else if (dmz_is_rnd(dzone))
+			list_add_tail(&dzone->link, &dzone->dev->map_rnd_list);
 		else
-			list_add_tail(&dzone->link, &zmd->map_seq_list);
+			list_add_tail(&dzone->link, &dzone->dev->map_seq_list);
 
 		/* Check buffer zone */
 		bzone_id = le32_to_cpu(dmap[e].bzone_id);
 		if (bzone_id == DMZ_MAP_UNMAPPED)
 			goto next;
 
-		if (bzone_id >= dev->nr_zones) {
-			dmz_dev_err(dev, "Chunk %u mapping: invalid buffer zone ID %u",
+		if (bzone_id >= zmd->nr_zones) {
+			dmz_zmd_err(zmd, "Chunk %u mapping: invalid buffer zone ID %u",
 				    chunk, bzone_id);
 			return -EIO;
 		}
 
 		bzone = dmz_get(zmd, bzone_id);
-		if (!dmz_is_rnd(bzone)) {
-			dmz_dev_err(dev, "Chunk %u mapping: invalid buffer zone %u",
+		if (!bzone) {
+			dmz_zmd_err(zmd, "Chunk %u mapping: buffer zone %u not present",
+				    chunk, bzone_id);
+			return -EIO;
+		}
+		if (!dmz_is_rnd(bzone) && !dmz_is_cache(bzone)) {
+			dmz_zmd_err(zmd, "Chunk %u mapping: invalid buffer zone %u",
 				    chunk, bzone_id);
 			return -EIO;
 		}
@@ -1385,7 +1773,10 @@ static int dmz_load_mapping(struct dmz_metadata *zmd)
 		bzone->bzone = dzone;
 		dzone->bzone = bzone;
 		dmz_get_zone_weight(zmd, bzone);
-		list_add_tail(&bzone->link, &zmd->map_rnd_list);
+		if (dmz_is_cache(bzone))
+			list_add_tail(&bzone->link, &zmd->map_cache_list);
+		else
+			list_add_tail(&bzone->link, &bzone->dev->map_rnd_list);
 next:
 		chunk++;
 		e++;
@@ -1398,15 +1789,21 @@ next:
 	 * fully initialized. All remaining zones are unmapped data
 	 * zones. Finish initializing those here.
 	 */
-	for (i = 0; i < dev->nr_zones; i++) {
+	for (i = 0; i < zmd->nr_zones; i++) {
 		dzone = dmz_get(zmd, i);
+		if (!dzone)
+			continue;
 		if (dmz_is_meta(dzone))
 			continue;
+		if (dmz_is_offline(dzone))
+			continue;
 
-		if (dmz_is_rnd(dzone))
-			zmd->nr_rnd++;
+		if (dmz_is_cache(dzone))
+			zmd->nr_cache++;
+		else if (dmz_is_rnd(dzone))
+			dzone->dev->nr_rnd++;
 		else
-			zmd->nr_seq++;
+			dzone->dev->nr_seq++;
 
 		if (dmz_is_data(dzone)) {
 			/* Already initialized */
@@ -1416,16 +1813,22 @@ next:
 		/* Unmapped data zone */
 		set_bit(DMZ_DATA, &dzone->flags);
 		dzone->chunk = DMZ_MAP_UNMAPPED;
-		if (dmz_is_rnd(dzone)) {
-			list_add_tail(&dzone->link, &zmd->unmap_rnd_list);
-			atomic_inc(&zmd->unmap_nr_rnd);
+		if (dmz_is_cache(dzone)) {
+			list_add_tail(&dzone->link, &zmd->unmap_cache_list);
+			atomic_inc(&zmd->unmap_nr_cache);
+		} else if (dmz_is_rnd(dzone)) {
+			list_add_tail(&dzone->link,
+				      &dzone->dev->unmap_rnd_list);
+			atomic_inc(&dzone->dev->unmap_nr_rnd);
 		} else if (atomic_read(&zmd->nr_reserved_seq_zones) < zmd->nr_reserved_seq) {
 			list_add_tail(&dzone->link, &zmd->reserved_seq_zones_list);
+			set_bit(DMZ_RESERVED, &dzone->flags);
 			atomic_inc(&zmd->nr_reserved_seq_zones);
-			zmd->nr_seq--;
+			dzone->dev->nr_seq--;
 		} else {
-			list_add_tail(&dzone->link, &zmd->unmap_seq_list);
-			atomic_inc(&zmd->unmap_nr_seq);
+			list_add_tail(&dzone->link,
+				      &dzone->dev->unmap_seq_list);
+			atomic_inc(&dzone->dev->unmap_nr_seq);
 		}
 	}
 
@@ -1459,10 +1862,13 @@ static void __dmz_lru_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 	list_del_init(&zone->link);
 	if (dmz_is_seq(zone)) {
 		/* LRU rotate sequential zone */
-		list_add_tail(&zone->link, &zmd->map_seq_list);
+		list_add_tail(&zone->link, &zone->dev->map_seq_list);
+	} else if (dmz_is_cache(zone)) {
+		/* LRU rotate cache zone */
+		list_add_tail(&zone->link, &zmd->map_cache_list);
 	} else {
 		/* LRU rotate random zone */
-		list_add_tail(&zone->link, &zmd->map_rnd_list);
+		list_add_tail(&zone->link, &zone->dev->map_rnd_list);
 	}
 }
 
@@ -1529,58 +1935,76 @@ static void dmz_wait_for_reclaim(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
 	dmz_unlock_map(zmd);
 	dmz_unlock_metadata(zmd);
+	set_bit(DMZ_RECLAIM_TERMINATE, &zone->flags);
 	wait_on_bit_timeout(&zone->flags, DMZ_RECLAIM, TASK_UNINTERRUPTIBLE, HZ);
+	clear_bit(DMZ_RECLAIM_TERMINATE, &zone->flags);
 	dmz_lock_metadata(zmd);
 	dmz_lock_map(zmd);
 }
 
 /*
- * Select a random write zone for reclaim.
+ * Select a cache or random write zone for reclaim.
  */
-static struct dm_zone *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd)
+static struct dm_zone *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd,
+						    unsigned int idx, bool idle)
 {
 	struct dm_zone *dzone = NULL;
-	struct dm_zone *zone;
-
-	if (list_empty(&zmd->map_rnd_list))
-		return ERR_PTR(-EBUSY);
+	struct dm_zone *zone, *last = NULL;
+	struct list_head *zone_list;
+
+	/* If we have cache zones select from the cache zone list */
+	if (zmd->nr_cache) {
+		zone_list = &zmd->map_cache_list;
+		/* Try to relaim random zones, too, when idle */
+		if (idle && list_empty(zone_list))
+			zone_list = &zmd->dev[idx].map_rnd_list;
+	} else
+		zone_list = &zmd->dev[idx].map_rnd_list;
 
-	list_for_each_entry(zone, &zmd->map_rnd_list, link) {
-		if (dmz_is_buf(zone))
+	list_for_each_entry(zone, zone_list, link) {
+		if (dmz_is_buf(zone)) {
 			dzone = zone->bzone;
-		else
+			if (dzone->dev->dev_idx != idx)
+				continue;
+			if (!last) {
+				last = dzone;
+				continue;
+			}
+			if (last->weight < dzone->weight)
+				continue;
+			dzone = last;
+		} else
 			dzone = zone;
 		if (dmz_lock_zone_reclaim(dzone))
 			return dzone;
 	}
 
-	return ERR_PTR(-EBUSY);
+	return NULL;
 }
 
 /*
  * Select a buffered sequential zone for reclaim.
  */
-static struct dm_zone *dmz_get_seq_zone_for_reclaim(struct dmz_metadata *zmd)
+static struct dm_zone *dmz_get_seq_zone_for_reclaim(struct dmz_metadata *zmd,
+						    unsigned int idx)
 {
 	struct dm_zone *zone;
 
-	if (list_empty(&zmd->map_seq_list))
-		return ERR_PTR(-EBUSY);
-
-	list_for_each_entry(zone, &zmd->map_seq_list, link) {
+	list_for_each_entry(zone, &zmd->dev[idx].map_seq_list, link) {
 		if (!zone->bzone)
 			continue;
 		if (dmz_lock_zone_reclaim(zone))
 			return zone;
 	}
 
-	return ERR_PTR(-EBUSY);
+	return NULL;
 }
 
 /*
  * Select a zone for reclaim.
  */
-struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd)
+struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd,
+					 unsigned int dev_idx, bool idle)
 {
 	struct dm_zone *zone;
 
@@ -1594,9 +2018,9 @@ struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd)
 	 */
 	dmz_lock_map(zmd);
 	if (list_empty(&zmd->reserved_seq_zones_list))
-		zone = dmz_get_seq_zone_for_reclaim(zmd);
+		zone = dmz_get_seq_zone_for_reclaim(zmd, dev_idx);
 	else
-		zone = dmz_get_rnd_zone_for_reclaim(zmd);
+		zone = dmz_get_rnd_zone_for_reclaim(zmd, dev_idx, idle);
 	dmz_unlock_map(zmd);
 
 	return zone;
@@ -1616,6 +2040,7 @@ struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd, unsigned int chu
 	unsigned int dzone_id;
 	struct dm_zone *dzone = NULL;
 	int ret = 0;
+	int alloc_flags = zmd->nr_cache ? DMZ_ALLOC_CACHE : DMZ_ALLOC_RND;
 
 	dmz_lock_map(zmd);
 again:
@@ -1630,9 +2055,9 @@ again:
 			goto out;
 
 		/* Allocate a random zone */
-		dzone = dmz_alloc_zone(zmd, DMZ_ALLOC_RND);
+		dzone = dmz_alloc_zone(zmd, 0, alloc_flags);
 		if (!dzone) {
-			if (dmz_bdev_is_dying(zmd->dev)) {
+			if (dmz_dev_is_dying(zmd)) {
 				dzone = ERR_PTR(-EIO);
 				goto out;
 			}
@@ -1645,6 +2070,10 @@ again:
 	} else {
 		/* The chunk is already mapped: get the mapping zone */
 		dzone = dmz_get(zmd, dzone_id);
+		if (!dzone) {
+			dzone = ERR_PTR(-EIO);
+			goto out;
+		}
 		if (dzone->chunk != chunk) {
 			dzone = ERR_PTR(-EIO);
 			goto out;
@@ -1723,6 +2152,7 @@ struct dm_zone *dmz_get_chunk_buffer(struct dmz_metadata *zmd,
 				     struct dm_zone *dzone)
 {
 	struct dm_zone *bzone;
+	int alloc_flags = zmd->nr_cache ? DMZ_ALLOC_CACHE : DMZ_ALLOC_RND;
 
 	dmz_lock_map(zmd);
 again:
@@ -1731,9 +2161,9 @@ again:
 		goto out;
 
 	/* Allocate a random zone */
-	bzone = dmz_alloc_zone(zmd, DMZ_ALLOC_RND);
+	bzone = dmz_alloc_zone(zmd, 0, alloc_flags);
 	if (!bzone) {
-		if (dmz_bdev_is_dying(zmd->dev)) {
+		if (dmz_dev_is_dying(zmd)) {
 			bzone = ERR_PTR(-EIO);
 			goto out;
 		}
@@ -1742,14 +2172,16 @@ again:
 	}
 
 	/* Update the chunk mapping */
-	dmz_set_chunk_mapping(zmd, dzone->chunk, dmz_id(zmd, dzone),
-			      dmz_id(zmd, bzone));
+	dmz_set_chunk_mapping(zmd, dzone->chunk, dzone->id, bzone->id);
 
 	set_bit(DMZ_BUF, &bzone->flags);
 	bzone->chunk = dzone->chunk;
 	bzone->bzone = dzone;
 	dzone->bzone = bzone;
-	list_add_tail(&bzone->link, &zmd->map_rnd_list);
+	if (dmz_is_cache(bzone))
+		list_add_tail(&bzone->link, &zmd->map_cache_list);
+	else
+		list_add_tail(&bzone->link, &bzone->dev->map_rnd_list);
 out:
 	dmz_unlock_map(zmd);
 
@@ -1760,46 +2192,68 @@ out:
  * Get an unmapped (free) zone.
  * This must be called with the mapping lock held.
  */
-struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned long flags)
+struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned int dev_idx,
+			       unsigned long flags)
 {
 	struct list_head *list;
 	struct dm_zone *zone;
+	int i = 0;
 
-	if (flags & DMZ_ALLOC_RND)
-		list = &zmd->unmap_rnd_list;
-	else
-		list = &zmd->unmap_seq_list;
 again:
+	if (flags & DMZ_ALLOC_CACHE)
+		list = &zmd->unmap_cache_list;
+	else if (flags & DMZ_ALLOC_RND)
+		list = &zmd->dev[dev_idx].unmap_rnd_list;
+	else
+		list = &zmd->dev[dev_idx].unmap_seq_list;
+
 	if (list_empty(list)) {
 		/*
-		 * No free zone: if this is for reclaim, allow using the
-		 * reserved sequential zones.
+		 * No free zone: return NULL if this is for not reclaim.
 		 */
-		if (!(flags & DMZ_ALLOC_RECLAIM) ||
-		    list_empty(&zmd->reserved_seq_zones_list))
+		if (!(flags & DMZ_ALLOC_RECLAIM))
 			return NULL;
+		/*
+		 * Try to allocate from other devices
+		 */
+		if (i < zmd->nr_devs) {
+			dev_idx = (dev_idx + 1) % zmd->nr_devs;
+			i++;
+			goto again;
+		}
 
-		zone = list_first_entry(&zmd->reserved_seq_zones_list,
-					struct dm_zone, link);
-		list_del_init(&zone->link);
-		atomic_dec(&zmd->nr_reserved_seq_zones);
+		/*
+		 * Fallback to the reserved sequential zones
+		 */
+		zone = list_first_entry_or_null(&zmd->reserved_seq_zones_list,
+						struct dm_zone, link);
+		if (zone) {
+			list_del_init(&zone->link);
+			atomic_dec(&zmd->nr_reserved_seq_zones);
+		}
 		return zone;
 	}
 
 	zone = list_first_entry(list, struct dm_zone, link);
 	list_del_init(&zone->link);
 
-	if (dmz_is_rnd(zone))
-		atomic_dec(&zmd->unmap_nr_rnd);
+	if (dmz_is_cache(zone))
+		atomic_dec(&zmd->unmap_nr_cache);
+	else if (dmz_is_rnd(zone))
+		atomic_dec(&zone->dev->unmap_nr_rnd);
 	else
-		atomic_dec(&zmd->unmap_nr_seq);
+		atomic_dec(&zone->dev->unmap_nr_seq);
 
 	if (dmz_is_offline(zone)) {
-		dmz_dev_warn(zmd->dev, "Zone %u is offline", dmz_id(zmd, zone));
+		dmz_zmd_warn(zmd, "Zone %u is offline", zone->id);
+		zone = NULL;
+		goto again;
+	}
+	if (dmz_is_meta(zone)) {
+		dmz_zmd_warn(zmd, "Zone %u has metadata", zone->id);
 		zone = NULL;
 		goto again;
 	}
-
 	return zone;
 }
 
@@ -1814,16 +2268,18 @@ void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 		dmz_reset_zone(zmd, zone);
 
 	/* Return the zone to its type unmap list */
-	if (dmz_is_rnd(zone)) {
-		list_add_tail(&zone->link, &zmd->unmap_rnd_list);
-		atomic_inc(&zmd->unmap_nr_rnd);
-	} else if (atomic_read(&zmd->nr_reserved_seq_zones) <
-		   zmd->nr_reserved_seq) {
+	if (dmz_is_cache(zone)) {
+		list_add_tail(&zone->link, &zmd->unmap_cache_list);
+		atomic_inc(&zmd->unmap_nr_cache);
+	} else if (dmz_is_rnd(zone)) {
+		list_add_tail(&zone->link, &zone->dev->unmap_rnd_list);
+		atomic_inc(&zone->dev->unmap_nr_rnd);
+	} else if (dmz_is_reserved(zone)) {
 		list_add_tail(&zone->link, &zmd->reserved_seq_zones_list);
 		atomic_inc(&zmd->nr_reserved_seq_zones);
 	} else {
-		list_add_tail(&zone->link, &zmd->unmap_seq_list);
-		atomic_inc(&zmd->unmap_nr_seq);
+		list_add_tail(&zone->link, &zone->dev->unmap_seq_list);
+		atomic_inc(&zone->dev->unmap_nr_seq);
 	}
 
 	wake_up_all(&zmd->free_wq);
@@ -1837,13 +2293,15 @@ void dmz_map_zone(struct dmz_metadata *zmd, struct dm_zone *dzone,
 		  unsigned int chunk)
 {
 	/* Set the chunk mapping */
-	dmz_set_chunk_mapping(zmd, chunk, dmz_id(zmd, dzone),
+	dmz_set_chunk_mapping(zmd, chunk, dzone->id,
 			      DMZ_MAP_UNMAPPED);
 	dzone->chunk = chunk;
-	if (dmz_is_rnd(dzone))
-		list_add_tail(&dzone->link, &zmd->map_rnd_list);
+	if (dmz_is_cache(dzone))
+		list_add_tail(&dzone->link, &zmd->map_cache_list);
+	else if (dmz_is_rnd(dzone))
+		list_add_tail(&dzone->link, &dzone->dev->map_rnd_list);
 	else
-		list_add_tail(&dzone->link, &zmd->map_seq_list);
+		list_add_tail(&dzone->link, &dzone->dev->map_seq_list);
 }
 
 /*
@@ -1865,7 +2323,7 @@ void dmz_unmap_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 		 * Unmapping the chunk buffer zone: clear only
 		 * the chunk buffer mapping
 		 */
-		dzone_id = dmz_id(zmd, zone->bzone);
+		dzone_id = zone->bzone->id;
 		zone->bzone->bzone = NULL;
 		zone->bzone = NULL;
 
@@ -1927,7 +2385,7 @@ static struct dmz_mblock *dmz_get_bitmap(struct dmz_metadata *zmd,
 					 sector_t chunk_block)
 {
 	sector_t bitmap_block = 1 + zmd->nr_map_blocks +
-		(sector_t)(dmz_id(zmd, zone) * zmd->zone_nr_bitmap_blocks) +
+		(sector_t)(zone->id * zmd->zone_nr_bitmap_blocks) +
 		(chunk_block >> DMZ_BLOCK_SHIFT_BITS);
 
 	return dmz_get_mblock(zmd, bitmap_block);
@@ -1943,7 +2401,7 @@ int dmz_copy_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
 	sector_t chunk_block = 0;
 
 	/* Get the zones bitmap blocks */
-	while (chunk_block < zmd->dev->zone_nr_blocks) {
+	while (chunk_block < zmd->zone_nr_blocks) {
 		from_mblk = dmz_get_bitmap(zmd, from_zone, chunk_block);
 		if (IS_ERR(from_mblk))
 			return PTR_ERR(from_mblk);
@@ -1978,7 +2436,7 @@ int dmz_merge_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
 	int ret;
 
 	/* Get the zones bitmap blocks */
-	while (chunk_block < zmd->dev->zone_nr_blocks) {
+	while (chunk_block < zmd->zone_nr_blocks) {
 		/* Get a valid region from the source zone */
 		ret = dmz_first_valid_block(zmd, from_zone, &chunk_block);
 		if (ret <= 0)
@@ -2002,12 +2460,12 @@ int dmz_validate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
 			sector_t chunk_block, unsigned int nr_blocks)
 {
 	unsigned int count, bit, nr_bits;
-	unsigned int zone_nr_blocks = zmd->dev->zone_nr_blocks;
+	unsigned int zone_nr_blocks = zmd->zone_nr_blocks;
 	struct dmz_mblock *mblk;
 	unsigned int n = 0;
 
-	dmz_dev_debug(zmd->dev, "=> VALIDATE zone %u, block %llu, %u blocks",
-		      dmz_id(zmd, zone), (unsigned long long)chunk_block,
+	dmz_zmd_debug(zmd, "=> VALIDATE zone %u, block %llu, %u blocks",
+		      zone->id, (unsigned long long)chunk_block,
 		      nr_blocks);
 
 	WARN_ON(chunk_block + nr_blocks > zone_nr_blocks);
@@ -2036,8 +2494,8 @@ int dmz_validate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
 	if (likely(zone->weight + n <= zone_nr_blocks))
 		zone->weight += n;
 	else {
-		dmz_dev_warn(zmd->dev, "Zone %u: weight %u should be <= %u",
-			     dmz_id(zmd, zone), zone->weight,
+		dmz_zmd_warn(zmd, "Zone %u: weight %u should be <= %u",
+			     zone->id, zone->weight,
 			     zone_nr_blocks - n);
 		zone->weight = zone_nr_blocks;
 	}
@@ -2086,10 +2544,10 @@ int dmz_invalidate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
 	struct dmz_mblock *mblk;
 	unsigned int n = 0;
 
-	dmz_dev_debug(zmd->dev, "=> INVALIDATE zone %u, block %llu, %u blocks",
-		      dmz_id(zmd, zone), (u64)chunk_block, nr_blocks);
+	dmz_zmd_debug(zmd, "=> INVALIDATE zone %u, block %llu, %u blocks",
+		      zone->id, (u64)chunk_block, nr_blocks);
 
-	WARN_ON(chunk_block + nr_blocks > zmd->dev->zone_nr_blocks);
+	WARN_ON(chunk_block + nr_blocks > zmd->zone_nr_blocks);
 
 	while (nr_blocks) {
 		/* Get bitmap block */
@@ -2116,8 +2574,8 @@ int dmz_invalidate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
 	if (zone->weight >= n)
 		zone->weight -= n;
 	else {
-		dmz_dev_warn(zmd->dev, "Zone %u: weight %u should be >= %u",
-			     dmz_id(zmd, zone), zone->weight, n);
+		dmz_zmd_warn(zmd, "Zone %u: weight %u should be >= %u",
+			     zone->id, zone->weight, n);
 		zone->weight = 0;
 	}
 
@@ -2133,7 +2591,7 @@ static int dmz_test_block(struct dmz_metadata *zmd, struct dm_zone *zone,
 	struct dmz_mblock *mblk;
 	int ret;
 
-	WARN_ON(chunk_block >= zmd->dev->zone_nr_blocks);
+	WARN_ON(chunk_block >= zmd->zone_nr_blocks);
 
 	/* Get bitmap block */
 	mblk = dmz_get_bitmap(zmd, zone, chunk_block);
@@ -2163,7 +2621,7 @@ static int dmz_to_next_set_block(struct dmz_metadata *zmd, struct dm_zone *zone,
 	unsigned long *bitmap;
 	int n = 0;
 
-	WARN_ON(chunk_block + nr_blocks > zmd->dev->zone_nr_blocks);
+	WARN_ON(chunk_block + nr_blocks > zmd->zone_nr_blocks);
 
 	while (nr_blocks) {
 		/* Get bitmap block */
@@ -2207,7 +2665,7 @@ int dmz_block_valid(struct dmz_metadata *zmd, struct dm_zone *zone,
 
 	/* The block is valid: get the number of valid blocks from block */
 	return dmz_to_next_set_block(zmd, zone, chunk_block,
-				     zmd->dev->zone_nr_blocks - chunk_block, 0);
+				     zmd->zone_nr_blocks - chunk_block, 0);
 }
 
 /*
@@ -2223,7 +2681,7 @@ int dmz_first_valid_block(struct dmz_metadata *zmd, struct dm_zone *zone,
 	int ret;
 
 	ret = dmz_to_next_set_block(zmd, zone, start_block,
-				    zmd->dev->zone_nr_blocks - start_block, 1);
+				    zmd->zone_nr_blocks - start_block, 1);
 	if (ret < 0)
 		return ret;
 
@@ -2231,7 +2689,7 @@ int dmz_first_valid_block(struct dmz_metadata *zmd, struct dm_zone *zone,
 	*chunk_block = start_block;
 
 	return dmz_to_next_set_block(zmd, zone, start_block,
-				     zmd->dev->zone_nr_blocks - start_block, 0);
+				     zmd->zone_nr_blocks - start_block, 0);
 }
 
 /*
@@ -2270,7 +2728,7 @@ static void dmz_get_zone_weight(struct dmz_metadata *zmd, struct dm_zone *zone)
 	struct dmz_mblock *mblk;
 	sector_t chunk_block = 0;
 	unsigned int bit, nr_bits;
-	unsigned int nr_blocks = zmd->dev->zone_nr_blocks;
+	unsigned int nr_blocks = zmd->zone_nr_blocks;
 	void *bitmap;
 	int n = 0;
 
@@ -2326,7 +2784,7 @@ static void dmz_cleanup_metadata(struct dmz_metadata *zmd)
 	while (!list_empty(&zmd->mblk_dirty_list)) {
 		mblk = list_first_entry(&zmd->mblk_dirty_list,
 					struct dmz_mblock, link);
-		dmz_dev_warn(zmd->dev, "mblock %llu still in dirty list (ref %u)",
+		dmz_zmd_warn(zmd, "mblock %llu still in dirty list (ref %u)",
 			     (u64)mblk->no, mblk->ref);
 		list_del_init(&mblk->link);
 		rb_erase(&mblk->node, &zmd->mblk_rbtree);
@@ -2344,7 +2802,7 @@ static void dmz_cleanup_metadata(struct dmz_metadata *zmd)
 	/* Sanity checks: the mblock rbtree should now be empty */
 	root = &zmd->mblk_rbtree;
 	rbtree_postorder_for_each_entry_safe(mblk, next, root, node) {
-		dmz_dev_warn(zmd->dev, "mblock %llu ref %u still in rbtree",
+		dmz_zmd_warn(zmd, "mblock %llu ref %u still in rbtree",
 			     (u64)mblk->no, mblk->ref);
 		mblk->ref = 0;
 		dmz_free_mblock(zmd, mblk);
@@ -2357,13 +2815,42 @@ static void dmz_cleanup_metadata(struct dmz_metadata *zmd)
 	mutex_destroy(&zmd->map_lock);
 }
 
+static void dmz_print_dev(struct dmz_metadata *zmd, int num)
+{
+	struct dmz_dev *dev = &zmd->dev[num];
+
+	if (bdev_zoned_model(dev->bdev) == BLK_ZONED_NONE)
+		dmz_dev_info(dev, "Regular block device");
+	else
+		dmz_dev_info(dev, "Host-%s zoned block device",
+			     bdev_zoned_model(dev->bdev) == BLK_ZONED_HA ?
+			     "aware" : "managed");
+	if (zmd->sb_version > 1) {
+		sector_t sector_offset =
+			dev->zone_offset << zmd->zone_nr_sectors_shift;
+
+		dmz_dev_info(dev, "  %llu 512-byte logical sectors (offset %llu)",
+			     (u64)dev->capacity, (u64)sector_offset);
+		dmz_dev_info(dev, "  %u zones of %llu 512-byte logical sectors (offset %llu)",
+			     dev->nr_zones, (u64)zmd->zone_nr_sectors,
+			     (u64)dev->zone_offset);
+	} else {
+		dmz_dev_info(dev, "  %llu 512-byte logical sectors",
+			     (u64)dev->capacity);
+		dmz_dev_info(dev, "  %u zones of %llu 512-byte logical sectors",
+			     dev->nr_zones, (u64)zmd->zone_nr_sectors);
+	}
+}
+
 /*
  * Initialize the zoned metadata.
  */
-int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **metadata)
+int dmz_ctr_metadata(struct dmz_dev *dev, int num_dev,
+		     struct dmz_metadata **metadata,
+		     const char *devname)
 {
 	struct dmz_metadata *zmd;
-	unsigned int i, zid;
+	unsigned int i;
 	struct dm_zone *zone;
 	int ret;
 
@@ -2371,7 +2858,9 @@ int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **metadata)
 	if (!zmd)
 		return -ENOMEM;
 
+	strcpy(zmd->devname, devname);
 	zmd->dev = dev;
+	zmd->nr_devs = num_dev;
 	zmd->mblk_rbtree = RB_ROOT;
 	init_rwsem(&zmd->mblk_sem);
 	mutex_init(&zmd->mblk_flush_lock);
@@ -2380,13 +2869,10 @@ int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **metadata)
 	INIT_LIST_HEAD(&zmd->mblk_dirty_list);
 
 	mutex_init(&zmd->map_lock);
-	atomic_set(&zmd->unmap_nr_rnd, 0);
-	INIT_LIST_HEAD(&zmd->unmap_rnd_list);
-	INIT_LIST_HEAD(&zmd->map_rnd_list);
 
-	atomic_set(&zmd->unmap_nr_seq, 0);
-	INIT_LIST_HEAD(&zmd->unmap_seq_list);
-	INIT_LIST_HEAD(&zmd->map_seq_list);
+	atomic_set(&zmd->unmap_nr_cache, 0);
+	INIT_LIST_HEAD(&zmd->unmap_cache_list);
+	INIT_LIST_HEAD(&zmd->map_cache_list);
 
 	atomic_set(&zmd->nr_reserved_seq_zones, 0);
 	INIT_LIST_HEAD(&zmd->reserved_seq_zones_list);
@@ -2404,14 +2890,22 @@ int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **metadata)
 		goto err;
 
 	/* Set metadata zones starting from sb_zone */
-	zid = dmz_id(zmd, zmd->sb_zone);
 	for (i = 0; i < zmd->nr_meta_zones << 1; i++) {
-		zone = dmz_get(zmd, zid + i);
-		if (!dmz_is_rnd(zone))
+		zone = dmz_get(zmd, zmd->sb[0].zone->id + i);
+		if (!zone) {
+			dmz_zmd_err(zmd,
+				    "metadata zone %u not present", i);
+			ret = -ENXIO;
+			goto err;
+		}
+		if (!dmz_is_rnd(zone) && !dmz_is_cache(zone)) {
+			dmz_zmd_err(zmd,
+				    "metadata zone %d is not random", i);
+			ret = -ENXIO;
 			goto err;
+		}
 		set_bit(DMZ_META, &zone->flags);
 	}
-
 	/* Load mapping table */
 	ret = dmz_load_mapping(zmd);
 	if (ret)
@@ -2432,34 +2926,38 @@ int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **metadata)
 	/* Metadata cache shrinker */
 	ret = register_shrinker(&zmd->mblk_shrinker);
 	if (ret) {
-		dmz_dev_err(dev, "Register metadata cache shrinker failed");
+		dmz_zmd_err(zmd, "Register metadata cache shrinker failed");
 		goto err;
 	}
 
-	dmz_dev_info(dev, "Host-%s zoned block device",
-		     bdev_zoned_model(dev->bdev) == BLK_ZONED_HA ?
-		     "aware" : "managed");
-	dmz_dev_info(dev, "  %llu 512-byte logical sectors",
-		     (u64)dev->capacity);
-	dmz_dev_info(dev, "  %u zones of %llu 512-byte logical sectors",
-		     dev->nr_zones, (u64)dev->zone_nr_sectors);
-	dmz_dev_info(dev, "  %u metadata zones",
-		     zmd->nr_meta_zones * 2);
-	dmz_dev_info(dev, "  %u data zones for %u chunks",
-		     zmd->nr_data_zones, zmd->nr_chunks);
-	dmz_dev_info(dev, "    %u random zones (%u unmapped)",
-		     zmd->nr_rnd, atomic_read(&zmd->unmap_nr_rnd));
-	dmz_dev_info(dev, "    %u sequential zones (%u unmapped)",
-		     zmd->nr_seq, atomic_read(&zmd->unmap_nr_seq));
-	dmz_dev_info(dev, "  %u reserved sequential data zones",
-		     zmd->nr_reserved_seq);
-
-	dmz_dev_debug(dev, "Format:");
-	dmz_dev_debug(dev, "%u metadata blocks per set (%u max cache)",
+	dmz_zmd_info(zmd, "DM-Zoned metadata version %d", zmd->sb_version);
+	for (i = 0; i < zmd->nr_devs; i++)
+		dmz_print_dev(zmd, i);
+
+	dmz_zmd_info(zmd, "  %u zones of %llu 512-byte logical sectors",
+		     zmd->nr_zones, (u64)zmd->zone_nr_sectors);
+	dmz_zmd_debug(zmd, "  %u metadata zones",
+		      zmd->nr_meta_zones * 2);
+	dmz_zmd_debug(zmd, "  %u data zones for %u chunks",
+		      zmd->nr_data_zones, zmd->nr_chunks);
+	dmz_zmd_debug(zmd, "    %u cache zones (%u unmapped)",
+		      zmd->nr_cache, atomic_read(&zmd->unmap_nr_cache));
+	for (i = 0; i < zmd->nr_devs; i++) {
+		dmz_zmd_debug(zmd, "    %u random zones (%u unmapped)",
+			      dmz_nr_rnd_zones(zmd, i),
+			      dmz_nr_unmap_rnd_zones(zmd, i));
+		dmz_zmd_debug(zmd, "    %u sequential zones (%u unmapped)",
+			      dmz_nr_seq_zones(zmd, i),
+			      dmz_nr_unmap_seq_zones(zmd, i));
+	}
+	dmz_zmd_debug(zmd, "  %u reserved sequential data zones",
+		      zmd->nr_reserved_seq);
+	dmz_zmd_debug(zmd, "Format:");
+	dmz_zmd_debug(zmd, "%u metadata blocks per set (%u max cache)",
 		      zmd->nr_meta_blocks, zmd->max_nr_mblks);
-	dmz_dev_debug(dev, "  %u data zone mapping blocks",
+	dmz_zmd_debug(zmd, "  %u data zone mapping blocks",
 		      zmd->nr_map_blocks);
-	dmz_dev_debug(dev, "  %u bitmap blocks",
+	dmz_zmd_debug(zmd, "  %u bitmap blocks",
 		      zmd->nr_bitmap_blocks);
 
 	*metadata = zmd;
@@ -2488,30 +2986,28 @@ void dmz_dtr_metadata(struct dmz_metadata *zmd)
  */
 int dmz_resume_metadata(struct dmz_metadata *zmd)
 {
-	struct dmz_dev *dev = zmd->dev;
 	struct dm_zone *zone;
 	sector_t wp_block;
 	unsigned int i;
 	int ret;
 
 	/* Check zones */
-	for (i = 0; i < dev->nr_zones; i++) {
+	for (i = 0; i < zmd->nr_zones; i++) {
 		zone = dmz_get(zmd, i);
 		if (!zone) {
-			dmz_dev_err(dev, "Unable to get zone %u", i);
+			dmz_zmd_err(zmd, "Unable to get zone %u", i);
 			return -EIO;
 		}
-
 		wp_block = zone->wp_block;
 
 		ret = dmz_update_zone(zmd, zone);
 		if (ret) {
-			dmz_dev_err(dev, "Broken zone %u", i);
+			dmz_zmd_err(zmd, "Broken zone %u", i);
 			return ret;
 		}
 
 		if (dmz_is_offline(zone)) {
-			dmz_dev_warn(dev, "Zone %u is offline", i);
+			dmz_zmd_warn(zmd, "Zone %u is offline", i);
 			continue;
 		}
 
@@ -2519,11 +3015,11 @@ int dmz_resume_metadata(struct dmz_metadata *zmd)
 		if (!dmz_is_seq(zone))
 			zone->wp_block = 0;
 		else if (zone->wp_block != wp_block) {
-			dmz_dev_err(dev, "Zone %u: Invalid wp (%llu / %llu)",
+			dmz_zmd_err(zmd, "Zone %u: Invalid wp (%llu / %llu)",
 				    i, (u64)zone->wp_block, (u64)wp_block);
 			zone->wp_block = wp_block;
 			dmz_invalidate_blocks(zmd, zone, zone->wp_block,
-					      dev->zone_nr_blocks - zone->wp_block);
+					      zmd->zone_nr_blocks - zone->wp_block);
 		}
 	}
 
diff --git a/drivers/md/dm-zoned-reclaim.c b/drivers/md/dm-zoned-reclaim.c
index e7ace908a9b7..2261b4dd60b7 100644
--- a/drivers/md/dm-zoned-reclaim.c
+++ b/drivers/md/dm-zoned-reclaim.c
@@ -13,7 +13,6 @@
 
 struct dmz_reclaim {
 	struct dmz_metadata     *metadata;
-	struct dmz_dev		*dev;
 
 	struct delayed_work	work;
 	struct workqueue_struct *wq;
@@ -22,6 +21,8 @@ struct dmz_reclaim {
 	struct dm_kcopyd_throttle kc_throttle;
 	int			kc_err;
 
+	int			dev_idx;
+
 	unsigned long		flags;
 
 	/* Last target access time */
@@ -44,13 +45,13 @@ enum {
  * Percentage of unmapped (free) random zones below which reclaim starts
  * even if the target is busy.
  */
-#define DMZ_RECLAIM_LOW_UNMAP_RND	30
+#define DMZ_RECLAIM_LOW_UNMAP_ZONES	30
 
 /*
  * Percentage of unmapped (free) random zones above which reclaim will
  * stop if the target is busy.
  */
-#define DMZ_RECLAIM_HIGH_UNMAP_RND	50
+#define DMZ_RECLAIM_HIGH_UNMAP_ZONES	50
 
 /*
  * Align a sequential zone write pointer to chunk_block.
@@ -59,6 +60,7 @@ static int dmz_reclaim_align_wp(struct dmz_reclaim *zrc, struct dm_zone *zone,
 				sector_t block)
 {
 	struct dmz_metadata *zmd = zrc->metadata;
+	struct dmz_dev *dev = zone->dev;
 	sector_t wp_block = zone->wp_block;
 	unsigned int nr_blocks;
 	int ret;
@@ -74,15 +76,15 @@ static int dmz_reclaim_align_wp(struct dmz_reclaim *zrc, struct dm_zone *zone,
 	 * pointer and the requested position.
 	 */
 	nr_blocks = block - wp_block;
-	ret = blkdev_issue_zeroout(zrc->dev->bdev,
+	ret = blkdev_issue_zeroout(dev->bdev,
 				   dmz_start_sect(zmd, zone) + dmz_blk2sect(wp_block),
 				   dmz_blk2sect(nr_blocks), GFP_NOIO, 0);
 	if (ret) {
-		dmz_dev_err(zrc->dev,
+		dmz_dev_err(dev,
 			    "Align zone %u wp %llu to %llu (wp+%u) blocks failed %d",
-			    dmz_id(zmd, zone), (unsigned long long)wp_block,
+			    zone->id, (unsigned long long)wp_block,
 			    (unsigned long long)block, nr_blocks, ret);
-		dmz_check_bdev(zrc->dev);
+		dmz_check_bdev(dev);
 		return ret;
 	}
 
@@ -116,7 +118,6 @@ static int dmz_reclaim_copy(struct dmz_reclaim *zrc,
 			    struct dm_zone *src_zone, struct dm_zone *dst_zone)
 {
 	struct dmz_metadata *zmd = zrc->metadata;
-	struct dmz_dev *dev = zrc->dev;
 	struct dm_io_region src, dst;
 	sector_t block = 0, end_block;
 	sector_t nr_blocks;
@@ -128,7 +129,7 @@ static int dmz_reclaim_copy(struct dmz_reclaim *zrc,
 	if (dmz_is_seq(src_zone))
 		end_block = src_zone->wp_block;
 	else
-		end_block = dev->zone_nr_blocks;
+		end_block = dmz_zone_nr_blocks(zmd);
 	src_zone_block = dmz_start_block(zmd, src_zone);
 	dst_zone_block = dmz_start_block(zmd, dst_zone);
 
@@ -136,9 +137,14 @@ static int dmz_reclaim_copy(struct dmz_reclaim *zrc,
 		set_bit(DM_KCOPYD_WRITE_SEQ, &flags);
 
 	while (block < end_block) {
-		if (dev->flags & DMZ_BDEV_DYING)
+		if (src_zone->dev->flags & DMZ_BDEV_DYING)
+			return -EIO;
+		if (dst_zone->dev->flags & DMZ_BDEV_DYING)
 			return -EIO;
 
+		if (dmz_reclaim_should_terminate(src_zone))
+			return -EINTR;
+
 		/* Get a valid region from the source zone */
 		ret = dmz_first_valid_block(zmd, src_zone, &block);
 		if (ret <= 0)
@@ -156,11 +162,11 @@ static int dmz_reclaim_copy(struct dmz_reclaim *zrc,
 				return ret;
 		}
 
-		src.bdev = dev->bdev;
+		src.bdev = src_zone->dev->bdev;
 		src.sector = dmz_blk2sect(src_zone_block + block);
 		src.count = dmz_blk2sect(nr_blocks);
 
-		dst.bdev = dev->bdev;
+		dst.bdev = dst_zone->dev->bdev;
 		dst.sector = dmz_blk2sect(dst_zone_block + block);
 		dst.count = src.count;
 
@@ -194,10 +200,10 @@ static int dmz_reclaim_buf(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 	struct dmz_metadata *zmd = zrc->metadata;
 	int ret;
 
-	dmz_dev_debug(zrc->dev,
-		      "Chunk %u, move buf zone %u (weight %u) to data zone %u (weight %u)",
-		      dzone->chunk, dmz_id(zmd, bzone), dmz_weight(bzone),
-		      dmz_id(zmd, dzone), dmz_weight(dzone));
+	DMDEBUG("(%s/%u): Chunk %u, move buf zone %u (weight %u) to data zone %u (weight %u)",
+		dmz_metadata_label(zmd), zrc->dev_idx,
+		dzone->chunk, bzone->id, dmz_weight(bzone),
+		dzone->id, dmz_weight(dzone));
 
 	/* Flush data zone into the buffer zone */
 	ret = dmz_reclaim_copy(zrc, bzone, dzone);
@@ -210,7 +216,7 @@ static int dmz_reclaim_buf(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 	ret = dmz_merge_valid_blocks(zmd, bzone, dzone, chunk_block);
 	if (ret == 0) {
 		/* Free the buffer zone */
-		dmz_invalidate_blocks(zmd, bzone, 0, zrc->dev->zone_nr_blocks);
+		dmz_invalidate_blocks(zmd, bzone, 0, dmz_zone_nr_blocks(zmd));
 		dmz_lock_map(zmd);
 		dmz_unmap_zone(zmd, bzone);
 		dmz_unlock_zone_reclaim(dzone);
@@ -233,10 +239,10 @@ static int dmz_reclaim_seq_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 	struct dmz_metadata *zmd = zrc->metadata;
 	int ret = 0;
 
-	dmz_dev_debug(zrc->dev,
-		      "Chunk %u, move data zone %u (weight %u) to buf zone %u (weight %u)",
-		      chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
-		      dmz_id(zmd, bzone), dmz_weight(bzone));
+	DMDEBUG("(%s/%u): Chunk %u, move data zone %u (weight %u) to buf zone %u (weight %u)",
+		dmz_metadata_label(zmd), zrc->dev_idx,
+		chunk, dzone->id, dmz_weight(dzone),
+		bzone->id, dmz_weight(bzone));
 
 	/* Flush data zone into the buffer zone */
 	ret = dmz_reclaim_copy(zrc, dzone, bzone);
@@ -252,7 +258,7 @@ static int dmz_reclaim_seq_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 		 * Free the data zone and remap the chunk to
 		 * the buffer zone.
 		 */
-		dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
+		dmz_invalidate_blocks(zmd, dzone, 0, dmz_zone_nr_blocks(zmd));
 		dmz_lock_map(zmd);
 		dmz_unmap_zone(zmd, bzone);
 		dmz_unmap_zone(zmd, dzone);
@@ -277,18 +283,26 @@ static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 	struct dm_zone *szone = NULL;
 	struct dmz_metadata *zmd = zrc->metadata;
 	int ret;
+	int alloc_flags = DMZ_ALLOC_SEQ;
 
-	/* Get a free sequential zone */
+	/* Get a free random or sequential zone */
 	dmz_lock_map(zmd);
-	szone = dmz_alloc_zone(zmd, DMZ_ALLOC_RECLAIM);
+again:
+	szone = dmz_alloc_zone(zmd, zrc->dev_idx,
+			       alloc_flags | DMZ_ALLOC_RECLAIM);
+	if (!szone && alloc_flags == DMZ_ALLOC_SEQ && dmz_nr_cache_zones(zmd)) {
+		alloc_flags = DMZ_ALLOC_RND;
+		goto again;
+	}
 	dmz_unlock_map(zmd);
 	if (!szone)
 		return -ENOSPC;
 
-	dmz_dev_debug(zrc->dev,
-		      "Chunk %u, move rnd zone %u (weight %u) to seq zone %u",
-		      chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
-		      dmz_id(zmd, szone));
+	DMDEBUG("(%s/%u): Chunk %u, move %s zone %u (weight %u) to %s zone %u",
+		dmz_metadata_label(zmd), zrc->dev_idx, chunk,
+		dmz_is_cache(dzone) ? "cache" : "rnd",
+		dzone->id, dmz_weight(dzone),
+		dmz_is_rnd(szone) ? "rnd" : "seq", szone->id);
 
 	/* Flush the random data zone into the sequential zone */
 	ret = dmz_reclaim_copy(zrc, dzone, szone);
@@ -306,7 +320,7 @@ static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 		dmz_unlock_map(zmd);
 	} else {
 		/* Free the data zone and remap the chunk */
-		dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
+		dmz_invalidate_blocks(zmd, dzone, 0, dmz_zone_nr_blocks(zmd));
 		dmz_lock_map(zmd);
 		dmz_unmap_zone(zmd, dzone);
 		dmz_unlock_zone_reclaim(dzone);
@@ -337,6 +351,14 @@ static void dmz_reclaim_empty(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 }
 
 /*
+ * Test if the target device is idle.
+ */
+static inline int dmz_target_idle(struct dmz_reclaim *zrc)
+{
+	return time_is_before_jiffies(zrc->atime + DMZ_IDLE_PERIOD);
+}
+
+/*
  * Find a candidate zone for reclaim and process it.
  */
 static int dmz_do_reclaim(struct dmz_reclaim *zrc)
@@ -348,13 +370,16 @@ static int dmz_do_reclaim(struct dmz_reclaim *zrc)
 	int ret;
 
 	/* Get a data zone */
-	dzone = dmz_get_zone_for_reclaim(zmd);
-	if (IS_ERR(dzone))
-		return PTR_ERR(dzone);
+	dzone = dmz_get_zone_for_reclaim(zmd, zrc->dev_idx,
+					 dmz_target_idle(zrc));
+	if (!dzone) {
+		DMDEBUG("(%s/%u): No zone found to reclaim",
+			dmz_metadata_label(zmd), zrc->dev_idx);
+		return -EBUSY;
+	}
 
 	start = jiffies;
-
-	if (dmz_is_rnd(dzone)) {
+	if (dmz_is_cache(dzone) || dmz_is_rnd(dzone)) {
 		if (!dmz_weight(dzone)) {
 			/* Empty zone */
 			dmz_reclaim_empty(zrc, dzone);
@@ -395,54 +420,80 @@ static int dmz_do_reclaim(struct dmz_reclaim *zrc)
 	}
 out:
 	if (ret) {
+		if (ret == -EINTR)
+			DMDEBUG("(%s/%u): reclaim zone %u interrupted",
+				dmz_metadata_label(zmd), zrc->dev_idx,
+				rzone->id);
+		else
+			DMDEBUG("(%s/%u): Failed to reclaim zone %u, err %d",
+				dmz_metadata_label(zmd), zrc->dev_idx,
+				rzone->id, ret);
 		dmz_unlock_zone_reclaim(dzone);
 		return ret;
 	}
 
 	ret = dmz_flush_metadata(zrc->metadata);
 	if (ret) {
-		dmz_dev_debug(zrc->dev,
-			      "Metadata flush for zone %u failed, err %d\n",
-			      dmz_id(zmd, rzone), ret);
+		DMDEBUG("(%s/%u): Metadata flush for zone %u failed, err %d",
+			dmz_metadata_label(zmd), zrc->dev_idx, rzone->id, ret);
 		return ret;
 	}
 
-	dmz_dev_debug(zrc->dev, "Reclaimed zone %u in %u ms",
-		      dmz_id(zmd, rzone), jiffies_to_msecs(jiffies - start));
+	DMDEBUG("(%s/%u): Reclaimed zone %u in %u ms",
+		dmz_metadata_label(zmd), zrc->dev_idx,
+		rzone->id, jiffies_to_msecs(jiffies - start));
 	return 0;
 }
 
-/*
- * Test if the target device is idle.
- */
-static inline int dmz_target_idle(struct dmz_reclaim *zrc)
+static unsigned int dmz_reclaim_percentage(struct dmz_reclaim *zrc)
 {
-	return time_is_before_jiffies(zrc->atime + DMZ_IDLE_PERIOD);
+	struct dmz_metadata *zmd = zrc->metadata;
+	unsigned int nr_cache = dmz_nr_cache_zones(zmd);
+	unsigned int nr_unmap, nr_zones;
+
+	if (nr_cache) {
+		nr_zones = nr_cache;
+		nr_unmap = dmz_nr_unmap_cache_zones(zmd);
+	} else {
+		nr_zones = dmz_nr_rnd_zones(zmd, zrc->dev_idx);
+		nr_unmap = dmz_nr_unmap_rnd_zones(zmd, zrc->dev_idx);
+	}
+	return nr_unmap * 100 / nr_zones;
 }
 
 /*
  * Test if reclaim is necessary.
  */
-static bool dmz_should_reclaim(struct dmz_reclaim *zrc)
+static bool dmz_should_reclaim(struct dmz_reclaim *zrc, unsigned int p_unmap)
 {
-	struct dmz_metadata *zmd = zrc->metadata;
-	unsigned int nr_rnd = dmz_nr_rnd_zones(zmd);
-	unsigned int nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
-	unsigned int p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;
+	unsigned int nr_reclaim;
+
+	nr_reclaim = dmz_nr_rnd_zones(zrc->metadata, zrc->dev_idx);
+
+	if (dmz_nr_cache_zones(zrc->metadata)) {
+		/*
+		 * The first device in a multi-device
+		 * setup only contains cache zones, so
+		 * never start reclaim there.
+		 */
+		if (zrc->dev_idx == 0)
+			return false;
+		nr_reclaim += dmz_nr_cache_zones(zrc->metadata);
+	}
 
 	/* Reclaim when idle */
-	if (dmz_target_idle(zrc) && nr_unmap_rnd < nr_rnd)
+	if (dmz_target_idle(zrc) && nr_reclaim)
 		return true;
 
-	/* If there are still plenty of random zones, do not reclaim */
-	if (p_unmap_rnd >= DMZ_RECLAIM_HIGH_UNMAP_RND)
+	/* If there are still plenty of cache zones, do not reclaim */
+	if (p_unmap >= DMZ_RECLAIM_HIGH_UNMAP_ZONES)
 		return false;
 
 	/*
-	 * If the percentage of unmapped random zones is low,
+	 * If the percentage of unmapped cache zones is low,
 	 * reclaim even if the target is busy.
 	 */
-	return p_unmap_rnd <= DMZ_RECLAIM_LOW_UNMAP_RND;
+	return p_unmap <= DMZ_RECLAIM_LOW_UNMAP_ZONES;
 }
 
 /*
@@ -452,14 +503,14 @@ static void dmz_reclaim_work(struct work_struct *work)
 {
 	struct dmz_reclaim *zrc = container_of(work, struct dmz_reclaim, work.work);
 	struct dmz_metadata *zmd = zrc->metadata;
-	unsigned int nr_rnd, nr_unmap_rnd;
-	unsigned int p_unmap_rnd;
+	unsigned int p_unmap, nr_unmap_rnd = 0, nr_rnd = 0;
 	int ret;
 
-	if (dmz_bdev_is_dying(zrc->dev))
+	if (dmz_dev_is_dying(zmd))
 		return;
 
-	if (!dmz_should_reclaim(zrc)) {
+	p_unmap = dmz_reclaim_percentage(zrc);
+	if (!dmz_should_reclaim(zrc, p_unmap)) {
 		mod_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
 		return;
 	}
@@ -470,27 +521,29 @@ static void dmz_reclaim_work(struct work_struct *work)
 	 * and slower if there are still some free random zones to avoid
 	 * as much as possible to negatively impact the user workload.
 	 */
-	nr_rnd = dmz_nr_rnd_zones(zmd);
-	nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
-	p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;
-	if (dmz_target_idle(zrc) || p_unmap_rnd < DMZ_RECLAIM_LOW_UNMAP_RND / 2) {
+	if (dmz_target_idle(zrc) || p_unmap < DMZ_RECLAIM_LOW_UNMAP_ZONES / 2) {
 		/* Idle or very low percentage: go fast */
 		zrc->kc_throttle.throttle = 100;
 	} else {
 		/* Busy but we still have some random zone: throttle */
-		zrc->kc_throttle.throttle = min(75U, 100U - p_unmap_rnd / 2);
+		zrc->kc_throttle.throttle = min(75U, 100U - p_unmap / 2);
 	}
 
-	dmz_dev_debug(zrc->dev,
-		      "Reclaim (%u): %s, %u%% free rnd zones (%u/%u)",
-		      zrc->kc_throttle.throttle,
-		      (dmz_target_idle(zrc) ? "Idle" : "Busy"),
-		      p_unmap_rnd, nr_unmap_rnd, nr_rnd);
+	nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd, zrc->dev_idx);
+	nr_rnd = dmz_nr_rnd_zones(zmd, zrc->dev_idx);
+
+	DMDEBUG("(%s/%u): Reclaim (%u): %s, %u%% free zones (%u/%u cache %u/%u random)",
+		dmz_metadata_label(zmd), zrc->dev_idx,
+		zrc->kc_throttle.throttle,
+		(dmz_target_idle(zrc) ? "Idle" : "Busy"),
+		p_unmap, dmz_nr_unmap_cache_zones(zmd),
+		dmz_nr_cache_zones(zmd),
+		dmz_nr_unmap_rnd_zones(zmd, zrc->dev_idx),
+		dmz_nr_rnd_zones(zmd, zrc->dev_idx));
 
 	ret = dmz_do_reclaim(zrc);
-	if (ret) {
-		dmz_dev_debug(zrc->dev, "Reclaim error %d\n", ret);
-		if (!dmz_check_bdev(zrc->dev))
+	if (ret && ret != -EINTR) {
+		if (!dmz_check_dev(zmd))
 			return;
 	}
 
@@ -500,8 +553,8 @@ static void dmz_reclaim_work(struct work_struct *work)
 /*
  * Initialize reclaim.
  */
-int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
-		    struct dmz_reclaim **reclaim)
+int dmz_ctr_reclaim(struct dmz_metadata *zmd,
+		    struct dmz_reclaim **reclaim, int idx)
 {
 	struct dmz_reclaim *zrc;
 	int ret;
@@ -510,9 +563,9 @@ int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
 	if (!zrc)
 		return -ENOMEM;
 
-	zrc->dev = dev;
 	zrc->metadata = zmd;
 	zrc->atime = jiffies;
+	zrc->dev_idx = idx;
 
 	/* Reclaim kcopyd client */
 	zrc->kc = dm_kcopyd_client_create(&zrc->kc_throttle);
@@ -524,8 +577,8 @@ int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
 
 	/* Reclaim work */
 	INIT_DELAYED_WORK(&zrc->work, dmz_reclaim_work);
-	zrc->wq = alloc_ordered_workqueue("dmz_rwq_%s", WQ_MEM_RECLAIM,
-					  dev->name);
+	zrc->wq = alloc_ordered_workqueue("dmz_rwq_%s_%d", WQ_MEM_RECLAIM,
+					  dmz_metadata_label(zmd), idx);
 	if (!zrc->wq) {
 		ret = -ENOMEM;
 		goto err;
@@ -583,7 +636,8 @@ void dmz_reclaim_bio_acc(struct dmz_reclaim *zrc)
  */
 void dmz_schedule_reclaim(struct dmz_reclaim *zrc)
 {
-	if (dmz_should_reclaim(zrc))
+	unsigned int p_unmap = dmz_reclaim_percentage(zrc);
+
+	if (dmz_should_reclaim(zrc, p_unmap))
 		mod_delayed_work(zrc->wq, &zrc->work, 0);
 }
-
diff --git a/drivers/md/dm-zoned-target.c b/drivers/md/dm-zoned-target.c
index f4f83d39b3dc..a907a9446c0b 100644
--- a/drivers/md/dm-zoned-target.c
+++ b/drivers/md/dm-zoned-target.c
@@ -17,7 +17,7 @@
  * Zone BIO context.
  */
 struct dmz_bioctx {
-	struct dmz_target	*target;
+	struct dmz_dev		*dev;
 	struct dm_zone		*zone;
 	struct bio		*bio;
 	refcount_t		ref;
@@ -38,9 +38,10 @@ struct dm_chunk_work {
  * Target descriptor.
  */
 struct dmz_target {
-	struct dm_dev		*ddev;
+	struct dm_dev		**ddev;
+	unsigned int		nr_ddevs;
 
-	unsigned long		flags;
+	unsigned int		flags;
 
 	/* Zoned block device information */
 	struct dmz_dev		*dev;
@@ -48,9 +49,6 @@ struct dmz_target {
 	/* For metadata handling */
 	struct dmz_metadata     *metadata;
 
-	/* For reclaim */
-	struct dmz_reclaim	*reclaim;
-
 	/* For chunk work */
 	struct radix_tree_root	chunk_rxtree;
 	struct workqueue_struct *chunk_wq;
@@ -76,12 +74,13 @@ struct dmz_target {
  */
 static inline void dmz_bio_endio(struct bio *bio, blk_status_t status)
 {
-	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+	struct dmz_bioctx *bioctx =
+		dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
 
 	if (status != BLK_STS_OK && bio->bi_status == BLK_STS_OK)
 		bio->bi_status = status;
-	if (bio->bi_status != BLK_STS_OK)
-		bioctx->target->dev->flags |= DMZ_CHECK_BDEV;
+	if (bioctx->dev && bio->bi_status != BLK_STS_OK)
+		bioctx->dev->flags |= DMZ_CHECK_BDEV;
 
 	if (refcount_dec_and_test(&bioctx->ref)) {
 		struct dm_zone *zone = bioctx->zone;
@@ -118,14 +117,20 @@ static int dmz_submit_bio(struct dmz_target *dmz, struct dm_zone *zone,
 			  struct bio *bio, sector_t chunk_block,
 			  unsigned int nr_blocks)
 {
-	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+	struct dmz_bioctx *bioctx =
+		dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+	struct dmz_dev *dev = zone->dev;
 	struct bio *clone;
 
+	if (dev->flags & DMZ_BDEV_DYING)
+		return -EIO;
+
 	clone = bio_clone_fast(bio, GFP_NOIO, &dmz->bio_set);
 	if (!clone)
 		return -ENOMEM;
 
-	bio_set_dev(clone, dmz->dev->bdev);
+	bio_set_dev(clone, dev->bdev);
+	bioctx->dev = dev;
 	clone->bi_iter.bi_sector =
 		dmz_start_sect(dmz->metadata, zone) + dmz_blk2sect(chunk_block);
 	clone->bi_iter.bi_size = dmz_blk2sect(nr_blocks) << SECTOR_SHIFT;
@@ -165,7 +170,8 @@ static void dmz_handle_read_zero(struct dmz_target *dmz, struct bio *bio,
 static int dmz_handle_read(struct dmz_target *dmz, struct dm_zone *zone,
 			   struct bio *bio)
 {
-	sector_t chunk_block = dmz_chunk_block(dmz->dev, dmz_bio_block(bio));
+	struct dmz_metadata *zmd = dmz->metadata;
+	sector_t chunk_block = dmz_chunk_block(zmd, dmz_bio_block(bio));
 	unsigned int nr_blocks = dmz_bio_blocks(bio);
 	sector_t end_block = chunk_block + nr_blocks;
 	struct dm_zone *rzone, *bzone;
@@ -177,19 +183,22 @@ static int dmz_handle_read(struct dmz_target *dmz, struct dm_zone *zone,
 		return 0;
 	}
 
-	dmz_dev_debug(dmz->dev, "READ chunk %llu -> %s zone %u, block %llu, %u blocks",
-		      (unsigned long long)dmz_bio_chunk(dmz->dev, bio),
-		      (dmz_is_rnd(zone) ? "RND" : "SEQ"),
-		      dmz_id(dmz->metadata, zone),
-		      (unsigned long long)chunk_block, nr_blocks);
+	DMDEBUG("(%s): READ chunk %llu -> %s zone %u, block %llu, %u blocks",
+		dmz_metadata_label(zmd),
+		(unsigned long long)dmz_bio_chunk(zmd, bio),
+		(dmz_is_rnd(zone) ? "RND" :
+		 (dmz_is_cache(zone) ? "CACHE" : "SEQ")),
+		zone->id,
+		(unsigned long long)chunk_block, nr_blocks);
 
 	/* Check block validity to determine the read location */
 	bzone = zone->bzone;
 	while (chunk_block < end_block) {
 		nr_blocks = 0;
-		if (dmz_is_rnd(zone) || chunk_block < zone->wp_block) {
+		if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
+		    chunk_block < zone->wp_block) {
 			/* Test block validity in the data zone */
-			ret = dmz_block_valid(dmz->metadata, zone, chunk_block);
+			ret = dmz_block_valid(zmd, zone, chunk_block);
 			if (ret < 0)
 				return ret;
 			if (ret > 0) {
@@ -204,7 +213,7 @@ static int dmz_handle_read(struct dmz_target *dmz, struct dm_zone *zone,
 		 * Check the buffer zone, if there is one.
 		 */
 		if (!nr_blocks && bzone) {
-			ret = dmz_block_valid(dmz->metadata, bzone, chunk_block);
+			ret = dmz_block_valid(zmd, bzone, chunk_block);
 			if (ret < 0)
 				return ret;
 			if (ret > 0) {
@@ -216,8 +225,10 @@ static int dmz_handle_read(struct dmz_target *dmz, struct dm_zone *zone,
 
 		if (nr_blocks) {
 			/* Valid blocks found: read them */
-			nr_blocks = min_t(unsigned int, nr_blocks, end_block - chunk_block);
-			ret = dmz_submit_bio(dmz, rzone, bio, chunk_block, nr_blocks);
+			nr_blocks = min_t(unsigned int, nr_blocks,
+					  end_block - chunk_block);
+			ret = dmz_submit_bio(dmz, rzone, bio,
+					     chunk_block, nr_blocks);
 			if (ret)
 				return ret;
 			chunk_block += nr_blocks;
@@ -308,25 +319,30 @@ static int dmz_handle_buffered_write(struct dmz_target *dmz,
 static int dmz_handle_write(struct dmz_target *dmz, struct dm_zone *zone,
 			    struct bio *bio)
 {
-	sector_t chunk_block = dmz_chunk_block(dmz->dev, dmz_bio_block(bio));
+	struct dmz_metadata *zmd = dmz->metadata;
+	sector_t chunk_block = dmz_chunk_block(zmd, dmz_bio_block(bio));
 	unsigned int nr_blocks = dmz_bio_blocks(bio);
 
 	if (!zone)
 		return -ENOSPC;
 
-	dmz_dev_debug(dmz->dev, "WRITE chunk %llu -> %s zone %u, block %llu, %u blocks",
-		      (unsigned long long)dmz_bio_chunk(dmz->dev, bio),
-		      (dmz_is_rnd(zone) ? "RND" : "SEQ"),
-		      dmz_id(dmz->metadata, zone),
-		      (unsigned long long)chunk_block, nr_blocks);
+	DMDEBUG("(%s): WRITE chunk %llu -> %s zone %u, block %llu, %u blocks",
+		dmz_metadata_label(zmd),
+		(unsigned long long)dmz_bio_chunk(zmd, bio),
+		(dmz_is_rnd(zone) ? "RND" :
+		 (dmz_is_cache(zone) ? "CACHE" : "SEQ")),
+		zone->id,
+		(unsigned long long)chunk_block, nr_blocks);
 
-	if (dmz_is_rnd(zone) || chunk_block == zone->wp_block) {
+	if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
+	    chunk_block == zone->wp_block) {
 		/*
 		 * zone is a random zone or it is a sequential zone
 		 * and the BIO is aligned to the zone write pointer:
 		 * direct write the zone.
 		 */
-		return dmz_handle_direct_write(dmz, zone, bio, chunk_block, nr_blocks);
+		return dmz_handle_direct_write(dmz, zone, bio,
+					       chunk_block, nr_blocks);
 	}
 
 	/*
@@ -345,7 +361,7 @@ static int dmz_handle_discard(struct dmz_target *dmz, struct dm_zone *zone,
 	struct dmz_metadata *zmd = dmz->metadata;
 	sector_t block = dmz_bio_block(bio);
 	unsigned int nr_blocks = dmz_bio_blocks(bio);
-	sector_t chunk_block = dmz_chunk_block(dmz->dev, block);
+	sector_t chunk_block = dmz_chunk_block(zmd, block);
 	int ret = 0;
 
 	/* For unmapped chunks, there is nothing to do */
@@ -355,16 +371,18 @@ static int dmz_handle_discard(struct dmz_target *dmz, struct dm_zone *zone,
 	if (dmz_is_readonly(zone))
 		return -EROFS;
 
-	dmz_dev_debug(dmz->dev, "DISCARD chunk %llu -> zone %u, block %llu, %u blocks",
-		      (unsigned long long)dmz_bio_chunk(dmz->dev, bio),
-		      dmz_id(zmd, zone),
-		      (unsigned long long)chunk_block, nr_blocks);
+	DMDEBUG("(%s): DISCARD chunk %llu -> zone %u, block %llu, %u blocks",
+		dmz_metadata_label(dmz->metadata),
+		(unsigned long long)dmz_bio_chunk(zmd, bio),
+		zone->id,
+		(unsigned long long)chunk_block, nr_blocks);
 
 	/*
 	 * Invalidate blocks in the data zone and its
 	 * buffer zone if one is mapped.
 	 */
-	if (dmz_is_rnd(zone) || chunk_block < zone->wp_block)
+	if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
+	    chunk_block < zone->wp_block)
 		ret = dmz_invalidate_blocks(zmd, zone, chunk_block, nr_blocks);
 	if (ret == 0 && zone->bzone)
 		ret = dmz_invalidate_blocks(zmd, zone->bzone,
@@ -378,31 +396,28 @@ static int dmz_handle_discard(struct dmz_target *dmz, struct dm_zone *zone,
 static void dmz_handle_bio(struct dmz_target *dmz, struct dm_chunk_work *cw,
 			   struct bio *bio)
 {
-	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+	struct dmz_bioctx *bioctx =
+		dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
 	struct dmz_metadata *zmd = dmz->metadata;
 	struct dm_zone *zone;
-	int ret;
+	int i, ret;
 
 	/*
 	 * Write may trigger a zone allocation. So make sure the
 	 * allocation can succeed.
 	 */
 	if (bio_op(bio) == REQ_OP_WRITE)
-		dmz_schedule_reclaim(dmz->reclaim);
+		for (i = 0; i < dmz->nr_ddevs; i++)
+			dmz_schedule_reclaim(dmz->dev[i].reclaim);
 
 	dmz_lock_metadata(zmd);
 
-	if (dmz->dev->flags & DMZ_BDEV_DYING) {
-		ret = -EIO;
-		goto out;
-	}
-
 	/*
 	 * Get the data zone mapping the chunk. There may be no
 	 * mapping for read and discard. If a mapping is obtained,
 	 + the zone returned will be set to active state.
 	 */
-	zone = dmz_get_chunk_mapping(zmd, dmz_bio_chunk(dmz->dev, bio),
+	zone = dmz_get_chunk_mapping(zmd, dmz_bio_chunk(zmd, bio),
 				     bio_op(bio));
 	if (IS_ERR(zone)) {
 		ret = PTR_ERR(zone);
@@ -413,6 +428,7 @@ static void dmz_handle_bio(struct dmz_target *dmz, struct dm_chunk_work *cw,
 	if (zone) {
 		dmz_activate_zone(zone);
 		bioctx->zone = zone;
+		dmz_reclaim_bio_acc(zone->dev->reclaim);
 	}
 
 	switch (bio_op(bio)) {
@@ -427,8 +443,8 @@ static void dmz_handle_bio(struct dmz_target *dmz, struct dm_chunk_work *cw,
 		ret = dmz_handle_discard(dmz, zone, bio);
 		break;
 	default:
-		dmz_dev_err(dmz->dev, "Unsupported BIO operation 0x%x",
-			    bio_op(bio));
+		DMERR("(%s): Unsupported BIO operation 0x%x",
+		      dmz_metadata_label(dmz->metadata), bio_op(bio));
 		ret = -EIO;
 	}
 
@@ -502,7 +518,8 @@ static void dmz_flush_work(struct work_struct *work)
 	/* Flush dirty metadata blocks */
 	ret = dmz_flush_metadata(dmz->metadata);
 	if (ret)
-		dmz_dev_debug(dmz->dev, "Metadata flush failed, rc=%d\n", ret);
+		DMDEBUG("(%s): Metadata flush failed, rc=%d",
+			dmz_metadata_label(dmz->metadata), ret);
 
 	/* Process queued flush requests */
 	while (1) {
@@ -525,7 +542,7 @@ static void dmz_flush_work(struct work_struct *work)
  */
 static int dmz_queue_chunk_work(struct dmz_target *dmz, struct bio *bio)
 {
-	unsigned int chunk = dmz_bio_chunk(dmz->dev, bio);
+	unsigned int chunk = dmz_bio_chunk(dmz->metadata, bio);
 	struct dm_chunk_work *cw;
 	int ret = 0;
 
@@ -558,7 +575,6 @@ static int dmz_queue_chunk_work(struct dmz_target *dmz, struct bio *bio)
 
 	bio_list_add(&cw->bio_list, bio);
 
-	dmz_reclaim_bio_acc(dmz->reclaim);
 	if (queue_work(dmz->chunk_wq, &cw->work))
 		dmz_get_chunk_work(cw);
 out:
@@ -618,23 +634,22 @@ bool dmz_check_bdev(struct dmz_dev *dmz_dev)
 static int dmz_map(struct dm_target *ti, struct bio *bio)
 {
 	struct dmz_target *dmz = ti->private;
-	struct dmz_dev *dev = dmz->dev;
+	struct dmz_metadata *zmd = dmz->metadata;
 	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
 	sector_t sector = bio->bi_iter.bi_sector;
 	unsigned int nr_sectors = bio_sectors(bio);
 	sector_t chunk_sector;
 	int ret;
 
-	if (dmz_bdev_is_dying(dmz->dev))
+	if (dmz_dev_is_dying(zmd))
 		return DM_MAPIO_KILL;
 
-	dmz_dev_debug(dev, "BIO op %d sector %llu + %u => chunk %llu, block %llu, %u blocks",
-		      bio_op(bio), (unsigned long long)sector, nr_sectors,
-		      (unsigned long long)dmz_bio_chunk(dmz->dev, bio),
-		      (unsigned long long)dmz_chunk_block(dmz->dev, dmz_bio_block(bio)),
-		      (unsigned int)dmz_bio_blocks(bio));
-
-	bio_set_dev(bio, dev->bdev);
+	DMDEBUG("(%s): BIO op %d sector %llu + %u => chunk %llu, block %llu, %u blocks",
+		dmz_metadata_label(zmd),
+		bio_op(bio), (unsigned long long)sector, nr_sectors,
+		(unsigned long long)dmz_bio_chunk(zmd, bio),
+		(unsigned long long)dmz_chunk_block(zmd, dmz_bio_block(bio)),
+		(unsigned int)dmz_bio_blocks(bio));
 
 	if (!nr_sectors && bio_op(bio) != REQ_OP_WRITE)
 		return DM_MAPIO_REMAPPED;
@@ -644,7 +659,7 @@ static int dmz_map(struct dm_target *ti, struct bio *bio)
 		return DM_MAPIO_KILL;
 
 	/* Initialize the BIO context */
-	bioctx->target = dmz;
+	bioctx->dev = NULL;
 	bioctx->zone = NULL;
 	bioctx->bio = bio;
 	refcount_set(&bioctx->ref, 1);
@@ -659,17 +674,17 @@ static int dmz_map(struct dm_target *ti, struct bio *bio)
 	}
 
 	/* Split zone BIOs to fit entirely into a zone */
-	chunk_sector = sector & (dev->zone_nr_sectors - 1);
-	if (chunk_sector + nr_sectors > dev->zone_nr_sectors)
-		dm_accept_partial_bio(bio, dev->zone_nr_sectors - chunk_sector);
+	chunk_sector = sector & (dmz_zone_nr_sectors(zmd) - 1);
+	if (chunk_sector + nr_sectors > dmz_zone_nr_sectors(zmd))
+		dm_accept_partial_bio(bio, dmz_zone_nr_sectors(zmd) - chunk_sector);
 
 	/* Now ready to handle this BIO */
 	ret = dmz_queue_chunk_work(dmz, bio);
 	if (ret) {
-		dmz_dev_debug(dmz->dev,
-			      "BIO op %d, can't process chunk %llu, err %i\n",
-			      bio_op(bio), (u64)dmz_bio_chunk(dmz->dev, bio),
-			      ret);
+		DMDEBUG("(%s): BIO op %d, can't process chunk %llu, err %i",
+			dmz_metadata_label(zmd),
+			bio_op(bio), (u64)dmz_bio_chunk(zmd, bio),
+			ret);
 		return DM_MAPIO_REQUEUE;
 	}
 
@@ -679,64 +694,65 @@ static int dmz_map(struct dm_target *ti, struct bio *bio)
 /*
  * Get zoned device information.
  */
-static int dmz_get_zoned_device(struct dm_target *ti, char *path)
+static int dmz_get_zoned_device(struct dm_target *ti, char *path,
+				int idx, int nr_devs)
 {
 	struct dmz_target *dmz = ti->private;
-	struct request_queue *q;
+	struct dm_dev *ddev;
 	struct dmz_dev *dev;
-	sector_t aligned_capacity;
 	int ret;
+	struct block_device *bdev;
 
 	/* Get the target device */
-	ret = dm_get_device(ti, path, dm_table_get_mode(ti->table), &dmz->ddev);
+	ret = dm_get_device(ti, path, dm_table_get_mode(ti->table), &ddev);
 	if (ret) {
 		ti->error = "Get target device failed";
-		dmz->ddev = NULL;
 		return ret;
 	}
 
-	dev = kzalloc(sizeof(struct dmz_dev), GFP_KERNEL);
-	if (!dev) {
-		ret = -ENOMEM;
-		goto err;
+	bdev = ddev->bdev;
+	if (bdev_zoned_model(bdev) == BLK_ZONED_NONE) {
+		if (nr_devs == 1) {
+			ti->error = "Invalid regular device";
+			goto err;
+		}
+		if (idx != 0) {
+			ti->error = "First device must be a regular device";
+			goto err;
+		}
+		if (dmz->ddev[0]) {
+			ti->error = "Too many regular devices";
+			goto err;
+		}
+		dev = &dmz->dev[idx];
+		dev->flags = DMZ_BDEV_REGULAR;
+	} else {
+		if (dmz->ddev[idx]) {
+			ti->error = "Too many zoned devices";
+			goto err;
+		}
+		if (nr_devs > 1 && idx == 0) {
+			ti->error = "First device must be a regular device";
+			goto err;
+		}
+		dev = &dmz->dev[idx];
 	}
-
-	dev->bdev = dmz->ddev->bdev;
+	dev->bdev = bdev;
+	dev->dev_idx = idx;
 	(void)bdevname(dev->bdev, dev->name);
 
-	if (bdev_zoned_model(dev->bdev) == BLK_ZONED_NONE) {
-		ti->error = "Not a zoned block device";
-		ret = -EINVAL;
+	dev->capacity = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
+	if (ti->begin) {
+		ti->error = "Partial mapping is not supported";
 		goto err;
 	}
 
-	q = bdev_get_queue(dev->bdev);
-	dev->capacity = i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
-	aligned_capacity = dev->capacity &
-				~((sector_t)blk_queue_zone_sectors(q) - 1);
-	if (ti->begin ||
-	    ((ti->len != dev->capacity) && (ti->len != aligned_capacity))) {
-		ti->error = "Partial mapping not supported";
-		ret = -EINVAL;
-		goto err;
-	}
-
-	dev->zone_nr_sectors = blk_queue_zone_sectors(q);
-	dev->zone_nr_sectors_shift = ilog2(dev->zone_nr_sectors);
-
-	dev->zone_nr_blocks = dmz_sect2blk(dev->zone_nr_sectors);
-	dev->zone_nr_blocks_shift = ilog2(dev->zone_nr_blocks);
-
-	dev->nr_zones = blkdev_nr_zones(dev->bdev->bd_disk);
-
-	dmz->dev = dev;
+	dmz->ddev[idx] = ddev;
 
 	return 0;
 err:
-	dm_put_device(ti, dmz->ddev);
-	kfree(dev);
-
-	return ret;
+	dm_put_device(ti, ddev);
+	return -EINVAL;
 }
 
 /*
@@ -745,10 +761,78 @@ err:
 static void dmz_put_zoned_device(struct dm_target *ti)
 {
 	struct dmz_target *dmz = ti->private;
+	int i;
 
-	dm_put_device(ti, dmz->ddev);
-	kfree(dmz->dev);
-	dmz->dev = NULL;
+	for (i = 0; i < dmz->nr_ddevs; i++) {
+		if (dmz->ddev[i]) {
+			dm_put_device(ti, dmz->ddev[i]);
+			dmz->ddev[i] = NULL;
+		}
+	}
+}
+
+static int dmz_fixup_devices(struct dm_target *ti)
+{
+	struct dmz_target *dmz = ti->private;
+	struct dmz_dev *reg_dev, *zoned_dev;
+	struct request_queue *q;
+	sector_t zone_nr_sectors = 0;
+	int i;
+
+	/*
+	 * When we have more than on devices, the first one must be a
+	 * regular block device and the others zoned block devices.
+	 */
+	if (dmz->nr_ddevs > 1) {
+		reg_dev = &dmz->dev[0];
+		if (!(reg_dev->flags & DMZ_BDEV_REGULAR)) {
+			ti->error = "Primary disk is not a regular device";
+			return -EINVAL;
+		}
+		for (i = 1; i < dmz->nr_ddevs; i++) {
+			zoned_dev = &dmz->dev[i];
+			if (zoned_dev->flags & DMZ_BDEV_REGULAR) {
+				ti->error = "Secondary disk is not a zoned device";
+				return -EINVAL;
+			}
+			q = bdev_get_queue(zoned_dev->bdev);
+			if (zone_nr_sectors &&
+			    zone_nr_sectors != blk_queue_zone_sectors(q)) {
+				ti->error = "Zone nr sectors mismatch";
+				return -EINVAL;
+			}
+			zone_nr_sectors = blk_queue_zone_sectors(q);
+			zoned_dev->zone_nr_sectors = zone_nr_sectors;
+			zoned_dev->nr_zones =
+				blkdev_nr_zones(zoned_dev->bdev->bd_disk);
+		}
+	} else {
+		reg_dev = NULL;
+		zoned_dev = &dmz->dev[0];
+		if (zoned_dev->flags & DMZ_BDEV_REGULAR) {
+			ti->error = "Disk is not a zoned device";
+			return -EINVAL;
+		}
+		q = bdev_get_queue(zoned_dev->bdev);
+		zoned_dev->zone_nr_sectors = blk_queue_zone_sectors(q);
+		zoned_dev->nr_zones = blkdev_nr_zones(zoned_dev->bdev->bd_disk);
+	}
+
+	if (reg_dev) {
+		sector_t zone_offset;
+
+		reg_dev->zone_nr_sectors = zone_nr_sectors;
+		reg_dev->nr_zones =
+			DIV_ROUND_UP_SECTOR_T(reg_dev->capacity,
+					      reg_dev->zone_nr_sectors);
+		reg_dev->zone_offset = 0;
+		zone_offset = reg_dev->nr_zones;
+		for (i = 1; i < dmz->nr_ddevs; i++) {
+			dmz->dev[i].zone_offset = zone_offset;
+			zone_offset += dmz->dev[i].nr_zones;
+		}
+	}
+	return 0;
 }
 
 /*
@@ -757,11 +841,10 @@ static void dmz_put_zoned_device(struct dm_target *ti)
 static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
 	struct dmz_target *dmz;
-	struct dmz_dev *dev;
-	int ret;
+	int ret, i;
 
 	/* Check arguments */
-	if (argc != 1) {
+	if (argc < 1) {
 		ti->error = "Invalid argument count";
 		return -EINVAL;
 	}
@@ -772,25 +855,42 @@ static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		ti->error = "Unable to allocate the zoned target descriptor";
 		return -ENOMEM;
 	}
+	dmz->dev = kcalloc(argc, sizeof(struct dmz_dev), GFP_KERNEL);
+	if (!dmz->dev) {
+		ti->error = "Unable to allocate the zoned device descriptors";
+		kfree(dmz);
+		return -ENOMEM;
+	}
+	dmz->ddev = kcalloc(argc, sizeof(struct dm_dev *), GFP_KERNEL);
+	if (!dmz->ddev) {
+		ti->error = "Unable to allocate the dm device descriptors";
+		ret = -ENOMEM;
+		goto err;
+	}
+	dmz->nr_ddevs = argc;
+
 	ti->private = dmz;
 
 	/* Get the target zoned block device */
-	ret = dmz_get_zoned_device(ti, argv[0]);
-	if (ret) {
-		dmz->ddev = NULL;
-		goto err;
+	for (i = 0; i < argc; i++) {
+		ret = dmz_get_zoned_device(ti, argv[i], i, argc);
+		if (ret)
+			goto err_dev;
 	}
+	ret = dmz_fixup_devices(ti);
+	if (ret)
+		goto err_dev;
 
 	/* Initialize metadata */
-	dev = dmz->dev;
-	ret = dmz_ctr_metadata(dev, &dmz->metadata);
+	ret = dmz_ctr_metadata(dmz->dev, argc, &dmz->metadata,
+			       dm_table_device_name(ti->table));
 	if (ret) {
 		ti->error = "Metadata initialization failed";
 		goto err_dev;
 	}
 
 	/* Set target (no write same support) */
-	ti->max_io_len = dev->zone_nr_sectors << 9;
+	ti->max_io_len = dmz_zone_nr_sectors(dmz->metadata) << 9;
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->num_write_zeroes_bios = 1;
@@ -799,7 +899,8 @@ static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ti->discards_supported = true;
 
 	/* The exposed capacity is the number of chunks that can be mapped */
-	ti->len = (sector_t)dmz_nr_chunks(dmz->metadata) << dev->zone_nr_sectors_shift;
+	ti->len = (sector_t)dmz_nr_chunks(dmz->metadata) <<
+		dmz_zone_nr_sectors_shift(dmz->metadata);
 
 	/* Zone BIO */
 	ret = bioset_init(&dmz->bio_set, DMZ_MIN_BIOS, 0, 0);
@@ -811,8 +912,9 @@ static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	/* Chunk BIO work */
 	mutex_init(&dmz->chunk_lock);
 	INIT_RADIX_TREE(&dmz->chunk_rxtree, GFP_NOIO);
-	dmz->chunk_wq = alloc_workqueue("dmz_cwq_%s", WQ_MEM_RECLAIM | WQ_UNBOUND,
-					0, dev->name);
+	dmz->chunk_wq = alloc_workqueue("dmz_cwq_%s",
+					WQ_MEM_RECLAIM | WQ_UNBOUND, 0,
+					dmz_metadata_label(dmz->metadata));
 	if (!dmz->chunk_wq) {
 		ti->error = "Create chunk workqueue failed";
 		ret = -ENOMEM;
@@ -824,7 +926,7 @@ static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	bio_list_init(&dmz->flush_list);
 	INIT_DELAYED_WORK(&dmz->flush_work, dmz_flush_work);
 	dmz->flush_wq = alloc_ordered_workqueue("dmz_fwq_%s", WQ_MEM_RECLAIM,
-						dev->name);
+						dmz_metadata_label(dmz->metadata));
 	if (!dmz->flush_wq) {
 		ti->error = "Create flush workqueue failed";
 		ret = -ENOMEM;
@@ -833,15 +935,18 @@ static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	mod_delayed_work(dmz->flush_wq, &dmz->flush_work, DMZ_FLUSH_PERIOD);
 
 	/* Initialize reclaim */
-	ret = dmz_ctr_reclaim(dev, dmz->metadata, &dmz->reclaim);
-	if (ret) {
-		ti->error = "Zone reclaim initialization failed";
-		goto err_fwq;
+	for (i = 0; i < dmz->nr_ddevs; i++) {
+		ret = dmz_ctr_reclaim(dmz->metadata, &dmz->dev[i].reclaim, i);
+		if (ret) {
+			ti->error = "Zone reclaim initialization failed";
+			goto err_fwq;
+		}
 	}
 
-	dmz_dev_info(dev, "Target device: %llu 512-byte logical sectors (%llu blocks)",
-		     (unsigned long long)ti->len,
-		     (unsigned long long)dmz_sect2blk(ti->len));
+	DMINFO("(%s): Target device: %llu 512-byte logical sectors (%llu blocks)",
+	       dmz_metadata_label(dmz->metadata),
+	       (unsigned long long)ti->len,
+	       (unsigned long long)dmz_sect2blk(ti->len));
 
 	return 0;
 err_fwq:
@@ -856,6 +961,7 @@ err_meta:
 err_dev:
 	dmz_put_zoned_device(ti);
 err:
+	kfree(dmz->dev);
 	kfree(dmz);
 
 	return ret;
@@ -867,11 +973,13 @@ err:
 static void dmz_dtr(struct dm_target *ti)
 {
 	struct dmz_target *dmz = ti->private;
+	int i;
 
 	flush_workqueue(dmz->chunk_wq);
 	destroy_workqueue(dmz->chunk_wq);
 
-	dmz_dtr_reclaim(dmz->reclaim);
+	for (i = 0; i < dmz->nr_ddevs; i++)
+		dmz_dtr_reclaim(dmz->dev[i].reclaim);
 
 	cancel_delayed_work_sync(&dmz->flush_work);
 	destroy_workqueue(dmz->flush_wq);
@@ -886,6 +994,7 @@ static void dmz_dtr(struct dm_target *ti)
 
 	mutex_destroy(&dmz->chunk_lock);
 
+	kfree(dmz->dev);
 	kfree(dmz);
 }
 
@@ -895,7 +1004,7 @@ static void dmz_dtr(struct dm_target *ti)
 static void dmz_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
 	struct dmz_target *dmz = ti->private;
-	unsigned int chunk_sectors = dmz->dev->zone_nr_sectors;
+	unsigned int chunk_sectors = dmz_zone_nr_sectors(dmz->metadata);
 
 	limits->logical_block_size = DMZ_BLOCK_SIZE;
 	limits->physical_block_size = DMZ_BLOCK_SIZE;
@@ -923,11 +1032,12 @@ static void dmz_io_hints(struct dm_target *ti, struct queue_limits *limits)
 static int dmz_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 {
 	struct dmz_target *dmz = ti->private;
+	struct dmz_dev *dev = &dmz->dev[0];
 
-	if (!dmz_check_bdev(dmz->dev))
+	if (!dmz_check_bdev(dev))
 		return -EIO;
 
-	*bdev = dmz->dev->bdev;
+	*bdev = dev->bdev;
 
 	return 0;
 }
@@ -938,9 +1048,11 @@ static int dmz_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 static void dmz_suspend(struct dm_target *ti)
 {
 	struct dmz_target *dmz = ti->private;
+	int i;
 
 	flush_workqueue(dmz->chunk_wq);
-	dmz_suspend_reclaim(dmz->reclaim);
+	for (i = 0; i < dmz->nr_ddevs; i++)
+		dmz_suspend_reclaim(dmz->dev[i].reclaim);
 	cancel_delayed_work_sync(&dmz->flush_work);
 }
 
@@ -950,24 +1062,95 @@ static void dmz_suspend(struct dm_target *ti)
 static void dmz_resume(struct dm_target *ti)
 {
 	struct dmz_target *dmz = ti->private;
+	int i;
 
 	queue_delayed_work(dmz->flush_wq, &dmz->flush_work, DMZ_FLUSH_PERIOD);
-	dmz_resume_reclaim(dmz->reclaim);
+	for (i = 0; i < dmz->nr_ddevs; i++)
+		dmz_resume_reclaim(dmz->dev[i].reclaim);
 }
 
 static int dmz_iterate_devices(struct dm_target *ti,
 			       iterate_devices_callout_fn fn, void *data)
 {
 	struct dmz_target *dmz = ti->private;
-	struct dmz_dev *dev = dmz->dev;
-	sector_t capacity = dev->capacity & ~(dev->zone_nr_sectors - 1);
+	unsigned int zone_nr_sectors = dmz_zone_nr_sectors(dmz->metadata);
+	sector_t capacity;
+	int i, r;
+
+	for (i = 0; i < dmz->nr_ddevs; i++) {
+		capacity = dmz->dev[i].capacity & ~(zone_nr_sectors - 1);
+		r = fn(ti, dmz->ddev[i], 0, capacity, data);
+		if (r)
+			break;
+	}
+	return r;
+}
+
+static void dmz_status(struct dm_target *ti, status_type_t type,
+		       unsigned int status_flags, char *result,
+		       unsigned int maxlen)
+{
+	struct dmz_target *dmz = ti->private;
+	ssize_t sz = 0;
+	char buf[BDEVNAME_SIZE];
+	struct dmz_dev *dev;
+	int i;
+
+	switch (type) {
+	case STATUSTYPE_INFO:
+		DMEMIT("%u zones %u/%u cache",
+		       dmz_nr_zones(dmz->metadata),
+		       dmz_nr_unmap_cache_zones(dmz->metadata),
+		       dmz_nr_cache_zones(dmz->metadata));
+		for (i = 0; i < dmz->nr_ddevs; i++) {
+			/*
+			 * For a multi-device setup the first device
+			 * contains only cache zones.
+			 */
+			if ((i == 0) &&
+			    (dmz_nr_cache_zones(dmz->metadata) > 0))
+				continue;
+			DMEMIT(" %u/%u random %u/%u sequential",
+			       dmz_nr_unmap_rnd_zones(dmz->metadata, i),
+			       dmz_nr_rnd_zones(dmz->metadata, i),
+			       dmz_nr_unmap_seq_zones(dmz->metadata, i),
+			       dmz_nr_seq_zones(dmz->metadata, i));
+		}
+		break;
+	case STATUSTYPE_TABLE:
+		dev = &dmz->dev[0];
+		format_dev_t(buf, dev->bdev->bd_dev);
+		DMEMIT("%s", buf);
+		for (i = 1; i < dmz->nr_ddevs; i++) {
+			dev = &dmz->dev[i];
+			format_dev_t(buf, dev->bdev->bd_dev);
+			DMEMIT(" %s", buf);
+		}
+		break;
+	}
+	return;
+}
+
+static int dmz_message(struct dm_target *ti, unsigned int argc, char **argv,
+		       char *result, unsigned int maxlen)
+{
+	struct dmz_target *dmz = ti->private;
+	int r = -EINVAL;
+
+	if (!strcasecmp(argv[0], "reclaim")) {
+		int i;
 
-	return fn(ti, dmz->ddev, 0, capacity, data);
+		for (i = 0; i < dmz->nr_ddevs; i++)
+			dmz_schedule_reclaim(dmz->dev[i].reclaim);
+		r = 0;
+	} else
+		DMERR("unrecognized message %s", argv[0]);
+	return r;
 }
 
 static struct target_type dmz_type = {
 	.name		 = "zoned",
-	.version	 = {1, 1, 0},
+	.version	 = {2, 0, 0},
 	.features	 = DM_TARGET_SINGLETON | DM_TARGET_ZONED_HM,
 	.module		 = THIS_MODULE,
 	.ctr		 = dmz_ctr,
@@ -978,6 +1161,8 @@ static struct target_type dmz_type = {
 	.postsuspend	 = dmz_suspend,
 	.resume		 = dmz_resume,
 	.iterate_devices = dmz_iterate_devices,
+	.status		 = dmz_status,
+	.message	 = dmz_message,
 };
 
 static int __init dmz_init(void)
diff --git a/drivers/md/dm-zoned.h b/drivers/md/dm-zoned.h
index 5b5e493d479c..22f11440b423 100644
--- a/drivers/md/dm-zoned.h
+++ b/drivers/md/dm-zoned.h
@@ -45,34 +45,50 @@
 #define dmz_bio_block(bio)	dmz_sect2blk((bio)->bi_iter.bi_sector)
 #define dmz_bio_blocks(bio)	dmz_sect2blk(bio_sectors(bio))
 
+struct dmz_metadata;
+struct dmz_reclaim;
+
 /*
  * Zoned block device information.
  */
 struct dmz_dev {
 	struct block_device	*bdev;
+	struct dmz_metadata	*metadata;
+	struct dmz_reclaim	*reclaim;
 
 	char			name[BDEVNAME_SIZE];
+	uuid_t			uuid;
 
 	sector_t		capacity;
 
+	unsigned int		dev_idx;
+
 	unsigned int		nr_zones;
+	unsigned int		zone_offset;
 
 	unsigned int		flags;
 
 	sector_t		zone_nr_sectors;
-	unsigned int		zone_nr_sectors_shift;
 
-	sector_t		zone_nr_blocks;
-	sector_t		zone_nr_blocks_shift;
+	unsigned int		nr_rnd;
+	atomic_t		unmap_nr_rnd;
+	struct list_head	unmap_rnd_list;
+	struct list_head	map_rnd_list;
+
+	unsigned int		nr_seq;
+	atomic_t		unmap_nr_seq;
+	struct list_head	unmap_seq_list;
+	struct list_head	map_seq_list;
 };
 
-#define dmz_bio_chunk(dev, bio)	((bio)->bi_iter.bi_sector >> \
-				 (dev)->zone_nr_sectors_shift)
-#define dmz_chunk_block(dev, b)	((b) & ((dev)->zone_nr_blocks - 1))
+#define dmz_bio_chunk(zmd, bio)	((bio)->bi_iter.bi_sector >> \
+				 dmz_zone_nr_sectors_shift(zmd))
+#define dmz_chunk_block(zmd, b)	((b) & (dmz_zone_nr_blocks(zmd) - 1))
 
 /* Device flags. */
 #define DMZ_BDEV_DYING		(1 << 0)
 #define DMZ_CHECK_BDEV		(2 << 0)
+#define DMZ_BDEV_REGULAR	(4 << 0)
 
 /*
  * Zone descriptor.
@@ -81,12 +97,18 @@ struct dm_zone {
 	/* For listing the zone depending on its state */
 	struct list_head	link;
 
+	/* Device containing this zone */
+	struct dmz_dev		*dev;
+
 	/* Zone type and state */
 	unsigned long		flags;
 
 	/* Zone activation reference count */
 	atomic_t		refcount;
 
+	/* Zone id */
+	unsigned int		id;
+
 	/* Zone write pointer block (relative to the zone start block) */
 	unsigned int		wp_block;
 
@@ -109,6 +131,7 @@ struct dm_zone {
  */
 enum {
 	/* Zone write type */
+	DMZ_CACHE,
 	DMZ_RND,
 	DMZ_SEQ,
 
@@ -120,22 +143,28 @@ enum {
 	DMZ_META,
 	DMZ_DATA,
 	DMZ_BUF,
+	DMZ_RESERVED,
 
 	/* Zone internal state */
 	DMZ_RECLAIM,
 	DMZ_SEQ_WRITE_ERR,
+	DMZ_RECLAIM_TERMINATE,
 };
 
 /*
  * Zone data accessors.
  */
+#define dmz_is_cache(z)		test_bit(DMZ_CACHE, &(z)->flags)
 #define dmz_is_rnd(z)		test_bit(DMZ_RND, &(z)->flags)
 #define dmz_is_seq(z)		test_bit(DMZ_SEQ, &(z)->flags)
 #define dmz_is_empty(z)		((z)->wp_block == 0)
 #define dmz_is_offline(z)	test_bit(DMZ_OFFLINE, &(z)->flags)
 #define dmz_is_readonly(z)	test_bit(DMZ_READ_ONLY, &(z)->flags)
 #define dmz_in_reclaim(z)	test_bit(DMZ_RECLAIM, &(z)->flags)
+#define dmz_is_reserved(z)	test_bit(DMZ_RESERVED, &(z)->flags)
 #define dmz_seq_write_err(z)	test_bit(DMZ_SEQ_WRITE_ERR, &(z)->flags)
+#define dmz_reclaim_should_terminate(z) \
+				test_bit(DMZ_RECLAIM_TERMINATE, &(z)->flags)
 
 #define dmz_is_meta(z)		test_bit(DMZ_META, &(z)->flags)
 #define dmz_is_buf(z)		test_bit(DMZ_BUF, &(z)->flags)
@@ -158,13 +187,11 @@ enum {
 #define dmz_dev_debug(dev, format, args...)	\
 	DMDEBUG("(%s): " format, (dev)->name, ## args)
 
-struct dmz_metadata;
-struct dmz_reclaim;
-
 /*
  * Functions defined in dm-zoned-metadata.c
  */
-int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **zmd);
+int dmz_ctr_metadata(struct dmz_dev *dev, int num_dev,
+		     struct dmz_metadata **zmd, const char *devname);
 void dmz_dtr_metadata(struct dmz_metadata *zmd);
 int dmz_resume_metadata(struct dmz_metadata *zmd);
 
@@ -175,23 +202,38 @@ void dmz_unlock_metadata(struct dmz_metadata *zmd);
 void dmz_lock_flush(struct dmz_metadata *zmd);
 void dmz_unlock_flush(struct dmz_metadata *zmd);
 int dmz_flush_metadata(struct dmz_metadata *zmd);
+const char *dmz_metadata_label(struct dmz_metadata *zmd);
 
-unsigned int dmz_id(struct dmz_metadata *zmd, struct dm_zone *zone);
 sector_t dmz_start_sect(struct dmz_metadata *zmd, struct dm_zone *zone);
 sector_t dmz_start_block(struct dmz_metadata *zmd, struct dm_zone *zone);
 unsigned int dmz_nr_chunks(struct dmz_metadata *zmd);
 
+bool dmz_check_dev(struct dmz_metadata *zmd);
+bool dmz_dev_is_dying(struct dmz_metadata *zmd);
+
 #define DMZ_ALLOC_RND		0x01
-#define DMZ_ALLOC_RECLAIM	0x02
+#define DMZ_ALLOC_CACHE		0x02
+#define DMZ_ALLOC_SEQ		0x04
+#define DMZ_ALLOC_RECLAIM	0x10
 
-struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned long flags);
+struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd,
+			       unsigned int dev_idx, unsigned long flags);
 void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
 
 void dmz_map_zone(struct dmz_metadata *zmd, struct dm_zone *zone,
 		  unsigned int chunk);
 void dmz_unmap_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
-unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd);
-unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd);
+unsigned int dmz_nr_zones(struct dmz_metadata *zmd);
+unsigned int dmz_nr_cache_zones(struct dmz_metadata *zmd);
+unsigned int dmz_nr_unmap_cache_zones(struct dmz_metadata *zmd);
+unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd, int idx);
+unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd, int idx);
+unsigned int dmz_nr_seq_zones(struct dmz_metadata *zmd, int idx);
+unsigned int dmz_nr_unmap_seq_zones(struct dmz_metadata *zmd, int idx);
+unsigned int dmz_zone_nr_blocks(struct dmz_metadata *zmd);
+unsigned int dmz_zone_nr_blocks_shift(struct dmz_metadata *zmd);
+unsigned int dmz_zone_nr_sectors(struct dmz_metadata *zmd);
+unsigned int dmz_zone_nr_sectors_shift(struct dmz_metadata *zmd);
 
 /*
  * Activate a zone (increment its reference count).
@@ -201,26 +243,10 @@ static inline void dmz_activate_zone(struct dm_zone *zone)
 	atomic_inc(&zone->refcount);
 }
 
-/*
- * Deactivate a zone. This decrement the zone reference counter
- * indicating that all BIOs to the zone have completed when the count is 0.
- */
-static inline void dmz_deactivate_zone(struct dm_zone *zone)
-{
-	atomic_dec(&zone->refcount);
-}
-
-/*
- * Test if a zone is active, that is, has a refcount > 0.
- */
-static inline bool dmz_is_active(struct dm_zone *zone)
-{
-	return atomic_read(&zone->refcount);
-}
-
 int dmz_lock_zone_reclaim(struct dm_zone *zone);
 void dmz_unlock_zone_reclaim(struct dm_zone *zone);
-struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd);
+struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd,
+					 unsigned int dev_idx, bool idle);
 
 struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd,
 				      unsigned int chunk, int op);
@@ -244,8 +270,7 @@ int dmz_merge_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
 /*
  * Functions defined in dm-zoned-reclaim.c
  */
-int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
-		    struct dmz_reclaim **zrc);
+int dmz_ctr_reclaim(struct dmz_metadata *zmd, struct dmz_reclaim **zrc, int idx);
 void dmz_dtr_reclaim(struct dmz_reclaim *zrc);
 void dmz_suspend_reclaim(struct dmz_reclaim *zrc);
 void dmz_resume_reclaim(struct dmz_reclaim *zrc);
@@ -258,4 +283,22 @@ void dmz_schedule_reclaim(struct dmz_reclaim *zrc);
 bool dmz_bdev_is_dying(struct dmz_dev *dmz_dev);
 bool dmz_check_bdev(struct dmz_dev *dmz_dev);
 
+/*
+ * Deactivate a zone. This decrement the zone reference counter
+ * indicating that all BIOs to the zone have completed when the count is 0.
+ */
+static inline void dmz_deactivate_zone(struct dm_zone *zone)
+{
+	dmz_reclaim_bio_acc(zone->dev->reclaim);
+	atomic_dec(&zone->refcount);
+}
+
+/*
+ * Test if a zone is active, that is, has a refcount > 0.
+ */
+static inline bool dmz_is_active(struct dm_zone *zone)
+{
+	return atomic_read(&zone->refcount);
+}
+
 #endif /* DM_ZONED_H */
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 3f39fa1ac756..109e81f33edb 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -676,6 +676,15 @@ static bool md_in_flight(struct mapped_device *md)
 		return md_in_flight_bios(md);
 }
 
+u64 dm_start_time_ns_from_clone(struct bio *bio)
+{
+	struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
+	struct dm_io *io = tio->io;
+
+	return jiffies_to_nsecs(io->start_time);
+}
+EXPORT_SYMBOL_GPL(dm_start_time_ns_from_clone);
+
 static void start_io_acct(struct dm_io *io)
 {
 	struct mapped_device *md = io->md;
@@ -2610,7 +2619,7 @@ static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
 	if (noflush)
 		set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
 	else
-		pr_debug("%s: suspending with flush\n", dm_device_name(md));
+		DMDEBUG("%s: suspending with flush", dm_device_name(md));
 
 	/*
 	 * This gets reverted if there's an error later and the targets
diff --git a/drivers/md/persistent-data/dm-btree-internal.h b/drivers/md/persistent-data/dm-btree-internal.h
index a240990a7f33..564896659dd4 100644
--- a/drivers/md/persistent-data/dm-btree-internal.h
+++ b/drivers/md/persistent-data/dm-btree-internal.h
@@ -38,7 +38,7 @@ struct node_header {
 
 struct btree_node {
 	struct node_header header;
-	__le64 keys[0];
+	__le64 keys[];
 } __packed;
 
 
@@ -68,7 +68,7 @@ struct ro_spine {
 };
 
 void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info);
-int exit_ro_spine(struct ro_spine *s);
+void exit_ro_spine(struct ro_spine *s);
 int ro_step(struct ro_spine *s, dm_block_t new_child);
 void ro_pop(struct ro_spine *s);
 struct btree_node *ro_node(struct ro_spine *s);
diff --git a/drivers/md/persistent-data/dm-btree-spine.c b/drivers/md/persistent-data/dm-btree-spine.c
index b27b8091a1ca..e03cb9e48773 100644
--- a/drivers/md/persistent-data/dm-btree-spine.c
+++ b/drivers/md/persistent-data/dm-btree-spine.c
@@ -132,15 +132,13 @@ void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info)
 	s->nodes[1] = NULL;
 }
 
-int exit_ro_spine(struct ro_spine *s)
+void exit_ro_spine(struct ro_spine *s)
 {
-	int r = 0, i;
+	int i;
 
 	for (i = 0; i < s->count; i++) {
 		unlock_block(s->info, s->nodes[i]);
 	}
-
-	return r;
 }
 
 int ro_step(struct ro_spine *s, dm_block_t new_child)