Merge tag 'for-4.16/dm-changes' of...

Merge tag 'for-4.16/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - DM core fixes to ensure that bio submission follows a depth-first
   tree walk; this is critical to allow forward progress without the
   need to use the bioset's BIOSET_NEED_RESCUER.

 - Remove DM core's BIOSET_NEED_RESCUER based dm_offload infrastructure.

 - DM core cleanups and improvements to make bio-based DM more efficient
   (e.g. reduced memory footprint as well leveraging per-bio-data more).

 - Introduce new bio-based mode (DM_TYPE_NVME_BIO_BASED) that leverages
   the more direct IO submission path in the block layer; this mode is
   used by DM multipath and also optimizes targets like DM thin-pool
   that stack directly on NVMe data device.

 - DM multipath improvements to factor out legacy SCSI-only (e.g.
   scsi_dh) code paths to allow for more optimized support for NVMe
   multipath.

 - A fix for DM multipath path selectors (service-time and queue-length)
   to select paths in a more balanced way; largely academic but doesn't
   hurt.

 - Numerous DM raid target fixes and improvements.

 - Add a new DM "unstriped" target that enables Intel to workaround
   firmware limitations in some NVMe drives that are striped internally
   (this target also works when stacked above the DM "striped" target).

 - Various Documentation fixes and improvements.

 - Misc cleanups and fixes across various DM infrastructure and targets
   (e.g. bufio, flakey, log-writes, snapshot).

* tag 'for-4.16/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (69 commits)
  dm cache: Documentation: update default migration_throttling value
  dm mpath selector: more evenly distribute ties
  dm unstripe: fix target length versus number of stripes size check
  dm thin: fix trailing semicolon in __remap_and_issue_shared_cell
  dm table: fix NVMe bio-based dm_table_determine_type() validation
  dm: various cleanups to md->queue initialization code
  dm mpath: delay the retry of a request if the target responded as busy
  dm mpath: return DM_MAPIO_DELAY_REQUEUE if QUEUE_IO or PG_INIT_REQUIRED
  dm mpath: return DM_MAPIO_REQUEUE on blk-mq rq allocation failure
  dm log writes: fix max length used for kstrndup
  dm: backfill missing calls to mutex_destroy()
  dm snapshot: use mutex instead of rw_semaphore
  dm flakey: check for null arg_name in parse_features()
  dm thin: extend thinpool status format string with omitted fields
  dm thin: fixes in thin-provisioning.txt
  dm thin: document representation of <highest mapped sector> when there is none
  dm thin: fix documentation relative to low water mark threshold
  dm cache: be consistent in specifying sectors and SI units in cache.txt
  dm cache: delete obsoleted paragraph in cache.txt
  dm cache: fix grammar in cache-policies.txt
  ...

Documentation/device-mapper/cache-policies.txt

@@ -60,7 +60,7 @@ Memory usage:
 The mq policy used a lot of memory; 88 bytes per cache block on a 64
 bit machine.
 
-smq uses 28bit indexes to implement it's data structures rather than
+smq uses 28bit indexes to implement its data structures rather than
 pointers.  It avoids storing an explicit hit count for each block.  It
 has a 'hotspot' queue, rather than a pre-cache, which uses a quarter of
 the entries (each hotspot block covers a larger area than a single
@@ -84,7 +84,7 @@ resulting in better promotion/demotion decisions.
 
 Adaptability:
 The mq policy maintained a hit count for each cache block.  For a
-different block to get promoted to the cache it's hit count has to
+different block to get promoted to the cache its hit count has to
 exceed the lowest currently in the cache.  This meant it could take a
 long time for the cache to adapt between varying IO patterns.
 

Documentation/device-mapper/cache.txt

@@ -59,7 +59,7 @@ Fixed block size
 The origin is divided up into blocks of a fixed size.  This block size
 is configurable when you first create the cache.  Typically we've been
 using block sizes of 256KB - 1024KB.  The block size must be between 64
-(32KB) and 2097152 (1GB) and a multiple of 64 (32KB).
+sectors (32KB) and 2097152 sectors (1GB) and a multiple of 64 sectors (32KB).
 
 Having a fixed block size simplifies the target a lot.  But it is
 something of a compromise.  For instance, a small part of a block may be
@@ -119,7 +119,7 @@ doing here to avoid migrating during those peak io moments.
 
 For the time being, a message "migration_threshold <#sectors>"
 can be used to set the maximum number of sectors being migrated,
-the default being 204800 sectors (or 100MB).
+the default being 2048 sectors (1MB).
 
 Updating on-disk metadata
 -------------------------
@@ -143,11 +143,6 @@ the policy how big this chunk is, but it should be kept small.  Like the
 dirty flags this data is lost if there's a crash so a safe fallback
 value should always be possible.
 
-For instance, the 'mq' policy, which is currently the default policy,
-uses this facility to store the hit count of the cache blocks.  If
-there's a crash this information will be lost, which means the cache
-may be less efficient until those hit counts are regenerated.
-
 Policy hints affect performance, not correctness.
 
 Policy messaging

Documentation/device-mapper/dm-raid.txt

@@ -343,5 +343,8 @@ Version History
 1.11.0  Fix table line argument order
 	(wrong raid10_copies/raid10_format sequence)
 1.11.1  Add raid4/5/6 journal write-back support via journal_mode option
-1.12.1  fix for MD deadlock between mddev_suspend() and md_write_start() available
+1.12.1  Fix for MD deadlock between mddev_suspend() and md_write_start() available
 1.13.0  Fix dev_health status at end of "recover" (was 'a', now 'A')
+1.13.1  Fix deadlock caused by early md_stop_writes().  Also fix size an
+	state races.
+1.13.2  Fix raid redundancy validation and avoid keeping raid set frozen

Documentation/device-mapper/snapshot.txt

@@ -49,6 +49,10 @@ The difference between persistent and transient is with transient
 snapshots less metadata must be saved on disk - they can be kept in
 memory by the kernel.
 
+When loading or unloading the snapshot target, the corresponding
+snapshot-origin or snapshot-merge target must be suspended. A failure to
+suspend the origin target could result in data corruption.
+
 
 * snapshot-merge <origin> <COW device> <persistent> <chunksize>
 

Documentation/device-mapper/thin-provisioning.txt

@@ -112,9 +112,11 @@ $low_water_mark is expressed in blocks of size $data_block_size.  If
 free space on the data device drops below this level then a dm event
 will be triggered which a userspace daemon should catch allowing it to
 extend the pool device.  Only one such event will be sent.
-Resuming a device with a new table itself triggers an event so the
-userspace daemon can use this to detect a situation where a new table
-already exceeds the threshold.
+
+No special event is triggered if a just resumed device's free space is below
+the low water mark. However, resuming a device always triggers an
+event; a userspace daemon should verify that free space exceeds the low
+water mark when handling this event.
 
 A low water mark for the metadata device is maintained in the kernel and
 will trigger a dm event if free space on the metadata device drops below
@@ -274,7 +276,8 @@ ii) Status
 
     <transaction id> <used metadata blocks>/<total metadata blocks>
     <used data blocks>/<total data blocks> <held metadata root>
-    [no_]discard_passdown ro|rw
+    ro|rw|out_of_data_space [no_]discard_passdown [error|queue]_if_no_space
+    needs_check|-
 
     transaction id:
 	A 64-bit number used by userspace to help synchronise with metadata
@@ -394,3 +397,6 @@ ii) Status
 	If the pool has encountered device errors and failed, the status
 	will just contain the string 'Fail'.  The userspace recovery
 	tools should then be used.
+
+    In the case where <nr mapped sectors> is 0, there is no highest
+    mapped sector and the value of <highest mapped sector> is unspecified.

Documentation/device-mapper/unstriped.txt

+Introduction
+============
+
+The device-mapper "unstriped" target provides a transparent mechanism to
+unstripe a device-mapper "striped" target to access the underlying disks
+without having to touch the true backing block-device.  It can also be
+used to unstripe a hardware RAID-0 to access backing disks.
+
+Parameters:
+<number of stripes> <chunk size> <stripe #> <dev_path> <offset>
+
+<number of stripes>
+        The number of stripes in the RAID 0.
+
+<chunk size>
+	The amount of 512B sectors in the chunk striping.
+
+<dev_path>
+	The block device you wish to unstripe.
+
+<stripe #>
+        The stripe number within the device that corresponds to physical
+        drive you wish to unstripe.  This must be 0 indexed.
+
+
+Why use this module?
+====================
+
+An example of undoing an existing dm-stripe
+-------------------------------------------
+
+This small bash script will setup 4 loop devices and use the existing
+striped target to combine the 4 devices into one.  It then will use
+the unstriped target ontop of the striped device to access the
+individual backing loop devices.  We write data to the newly exposed
+unstriped devices and verify the data written matches the correct
+underlying device on the striped array.
+
+#!/bin/bash
+
+MEMBER_SIZE=$((128 * 1024 * 1024))
+NUM=4
+SEQ_END=$((${NUM}-1))
+CHUNK=256
+BS=4096
+
+RAID_SIZE=$((${MEMBER_SIZE}*${NUM}/512))
+DM_PARMS="0 ${RAID_SIZE} striped ${NUM} ${CHUNK}"
+COUNT=$((${MEMBER_SIZE} / ${BS}))
+
+for i in $(seq 0 ${SEQ_END}); do
+  dd if=/dev/zero of=member-${i} bs=${MEMBER_SIZE} count=1 oflag=direct
+  losetup /dev/loop${i} member-${i}
+  DM_PARMS+=" /dev/loop${i} 0"
+done
+
+echo $DM_PARMS | dmsetup create raid0
+for i in $(seq 0 ${SEQ_END}); do
+  echo "0 1 unstriped ${NUM} ${CHUNK} ${i} /dev/mapper/raid0 0" | dmsetup create set-${i}
+done;
+
+for i in $(seq 0 ${SEQ_END}); do
+  dd if=/dev/urandom of=/dev/mapper/set-${i} bs=${BS} count=${COUNT} oflag=direct
+  diff /dev/mapper/set-${i} member-${i}
+done;
+
+for i in $(seq 0 ${SEQ_END}); do
+  dmsetup remove set-${i}
+done
+
+dmsetup remove raid0
+
+for i in $(seq 0 ${SEQ_END}); do
+  losetup -d /dev/loop${i}
+  rm -f member-${i}
+done
+
+Another example
+---------------
+
+Intel NVMe drives contain two cores on the physical device.
+Each core of the drive has segregated access to its LBA range.
+The current LBA model has a RAID 0 128k chunk on each core, resulting
+in a 256k stripe across the two cores:
+
+   Core 0:       Core 1:
+  __________    __________
+  | LBA 512|    | LBA 768|
+  | LBA 0  |    | LBA 256|
+  ----------    ----------
+
+The purpose of this unstriping is to provide better QoS in noisy
+neighbor environments. When two partitions are created on the
+aggregate drive without this unstriping, reads on one partition
+can affect writes on another partition.  This is because the partitions
+are striped across the two cores.  When we unstripe this hardware RAID 0
+and make partitions on each new exposed device the two partitions are now
+physically separated.
+
+With the dm-unstriped target we're able to segregate an fio script that
+has read and write jobs that are independent of each other.  Compared to
+when we run the test on a combined drive with partitions, we were able
+to get a 92% reduction in read latency using this device mapper target.
+
+
+Example dmsetup usage
+=====================
+
+unstriped ontop of Intel NVMe device that has 2 cores
+-----------------------------------------------------
+dmsetup create nvmset0 --table '0 512 unstriped 2 256 0 /dev/nvme0n1 0'
+dmsetup create nvmset1 --table '0 512 unstriped 2 256 1 /dev/nvme0n1 0'
+
+There will now be two devices that expose Intel NVMe core 0 and 1
+respectively:
+/dev/mapper/nvmset0
+/dev/mapper/nvmset1
+
+unstriped ontop of striped with 4 drives using 128K chunk size
+--------------------------------------------------------------
+dmsetup create raid_disk0 --table '0 512 unstriped 4 256 0 /dev/mapper/striped 0'
+dmsetup create raid_disk1 --table '0 512 unstriped 4 256 1 /dev/mapper/striped 0'
+dmsetup create raid_disk2 --table '0 512 unstriped 4 256 2 /dev/mapper/striped 0'
+dmsetup create raid_disk3 --table '0 512 unstriped 4 256 3 /dev/mapper/striped 0'

drivers/md/Kconfig

@@ -269,6 +269,13 @@ config DM_BIO_PRISON
 
 source "drivers/md/persistent-data/Kconfig"
 
+config DM_UNSTRIPED
+       tristate "Unstriped target"
+       depends on BLK_DEV_DM
+       ---help---
+	  Unstripes I/O so it is issued solely on a single drive in a HW
+	  RAID0 or dm-striped target.
+
 config DM_CRYPT
 	tristate "Crypt target support"
 	depends on BLK_DEV_DM

drivers/md/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_BCACHE)		+= bcache/
 obj-$(CONFIG_BLK_DEV_MD)	+= md-mod.o
 obj-$(CONFIG_BLK_DEV_DM)	+= dm-mod.o
 obj-$(CONFIG_BLK_DEV_DM_BUILTIN) += dm-builtin.o
+obj-$(CONFIG_DM_UNSTRIPED)	+= dm-unstripe.o
 obj-$(CONFIG_DM_BUFIO)		+= dm-bufio.o
 obj-$(CONFIG_DM_BIO_PRISON)	+= dm-bio-prison.o
 obj-$(CONFIG_DM_CRYPT)		+= dm-crypt.o

drivers/md/dm-bufio.c

@@ -662,7 +662,7 @@ static void submit_io(struct dm_buffer *b, int rw, bio_end_io_t *end_io)
 
 	sector = (b->block << b->c->sectors_per_block_bits) + b->c->start;
 
-	if (rw != WRITE) {
+	if (rw != REQ_OP_WRITE) {
 		n_sectors = 1 << b->c->sectors_per_block_bits;
 		offset = 0;
 	} else {
@@ -740,7 +740,7 @@ static void __write_dirty_buffer(struct dm_buffer *b,
 	b->write_end = b->dirty_end;
 
 	if (!write_list)
-		submit_io(b, WRITE, write_endio);
+		submit_io(b, REQ_OP_WRITE, write_endio);
 	else
 		list_add_tail(&b->write_list, write_list);
 }
@@ -753,7 +753,7 @@ static void __flush_write_list(struct list_head *write_list)
 		struct dm_buffer *b =
 			list_entry(write_list->next, struct dm_buffer, write_list);
 		list_del(&b->write_list);
-		submit_io(b, WRITE, write_endio);
+		submit_io(b, REQ_OP_WRITE, write_endio);
 		cond_resched();
 	}
 	blk_finish_plug(&plug);
@@ -1123,7 +1123,7 @@ static void *new_read(struct dm_bufio_client *c, sector_t block,
 		return NULL;
 
 	if (need_submit)
-		submit_io(b, READ, read_endio);
+		submit_io(b, REQ_OP_READ, read_endio);
 
 	wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
 
@@ -1193,7 +1193,7 @@ void dm_bufio_prefetch(struct dm_bufio_client *c,
 			dm_bufio_unlock(c);
 
 			if (need_submit)
-				submit_io(b, READ, read_endio);
+				submit_io(b, REQ_OP_READ, read_endio);
 			dm_bufio_release(b);
 
 			cond_resched();
@@ -1454,7 +1454,7 @@ void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
 		old_block = b->block;
 		__unlink_buffer(b);
 		__link_buffer(b, new_block, b->list_mode);
-		submit_io(b, WRITE, write_endio);
+		submit_io(b, REQ_OP_WRITE, write_endio);
 		wait_on_bit_io(&b->state, B_WRITING,
 			       TASK_UNINTERRUPTIBLE);
 		__unlink_buffer(b);
@@ -1716,7 +1716,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 			if (!DM_BUFIO_CACHE_NAME(c)) {
 				r = -ENOMEM;
 				mutex_unlock(&dm_bufio_clients_lock);
-				goto bad_cache;
+				goto bad;
 			}
 		}
 
@@ -1727,7 +1727,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 			if (!DM_BUFIO_CACHE(c)) {
 				r = -ENOMEM;
 				mutex_unlock(&dm_bufio_clients_lock);
-				goto bad_cache;
+				goto bad;
 			}
 		}
 	}
@@ -1738,27 +1738,28 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 
 		if (!b) {
 			r = -ENOMEM;
-			goto bad_buffer;
+			goto bad;
 		}
 		__free_buffer_wake(b);
 	}
 
+	c->shrinker.count_objects = dm_bufio_shrink_count;
+	c->shrinker.scan_objects = dm_bufio_shrink_scan;
+	c->shrinker.seeks = 1;
+	c->shrinker.batch = 0;
+	r = register_shrinker(&c->shrinker);
+	if (r)
+		goto bad;
+
 	mutex_lock(&dm_bufio_clients_lock);
 	dm_bufio_client_count++;
 	list_add(&c->client_list, &dm_bufio_all_clients);
 	__cache_size_refresh();
 	mutex_unlock(&dm_bufio_clients_lock);
 
-	c->shrinker.count_objects = dm_bufio_shrink_count;
-	c->shrinker.scan_objects = dm_bufio_shrink_scan;
-	c->shrinker.seeks = 1;
-	c->shrinker.batch = 0;
-	register_shrinker(&c->shrinker);
-
 	return c;
 
-bad_buffer:
-bad_cache:
+bad:
 	while (!list_empty(&c->reserved_buffers)) {
 		struct dm_buffer *b = list_entry(c->reserved_buffers.next,
 						 struct dm_buffer, lru_list);
@@ -1767,6 +1768,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 	}
 	dm_io_client_destroy(c->dm_io);
 bad_dm_io:
+	mutex_destroy(&c->lock);
 	kfree(c);
 bad_client:
 	return ERR_PTR(r);
@@ -1811,6 +1813,7 @@ void dm_bufio_client_destroy(struct dm_bufio_client *c)
 		BUG_ON(c->n_buffers[i]);
 
 	dm_io_client_destroy(c->dm_io);
+	mutex_destroy(&c->lock);
 	kfree(c);
 }
 EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);

drivers/md/dm-core.h

@@ -91,8 +91,7 @@ struct mapped_device {
 	/*
 	 * io objects are allocated from here.
 	 */
-	mempool_t *io_pool;
-
+	struct bio_set *io_bs;
 	struct bio_set *bs;
 
 	/*
@@ -130,8 +129,6 @@ struct mapped_device {
 	struct srcu_struct io_barrier;
 };
 
-void dm_init_md_queue(struct mapped_device *md);
-void dm_init_normal_md_queue(struct mapped_device *md);
 int md_in_flight(struct mapped_device *md);
 void disable_write_same(struct mapped_device *md);
 void disable_write_zeroes(struct mapped_device *md);

drivers/md/dm-crypt.c

@@ -2193,6 +2193,8 @@ static void crypt_dtr(struct dm_target *ti)
 	kzfree(cc->cipher_auth);
 	kzfree(cc->authenc_key);
 
+	mutex_destroy(&cc->bio_alloc_lock);
+
 	/* Must zero key material before freeing */
 	kzfree(cc);
 }
@@ -2702,8 +2704,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad;
 	}
 
-	cc->bs = bioset_create(MIN_IOS, 0, (BIOSET_NEED_BVECS |
-					    BIOSET_NEED_RESCUER));
+	cc->bs = bioset_create(MIN_IOS, 0, BIOSET_NEED_BVECS);
 	if (!cc->bs) {
 		ti->error = "Cannot allocate crypt bioset";
 		goto bad;

drivers/md/dm-delay.c

@@ -229,6 +229,8 @@ static void delay_dtr(struct dm_target *ti)
 	if (dc->dev_write)
 		dm_put_device(ti, dc->dev_write);
 
+	mutex_destroy(&dc->timer_lock);
+
 	kfree(dc);
 }
 

drivers/md/dm-flakey.c

@@ -70,6 +70,11 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
 		arg_name = dm_shift_arg(as);
 		argc--;
 
+		if (!arg_name) {
+			ti->error = "Insufficient feature arguments";
+			return -EINVAL;
+		}
+
 		/*
 		 * drop_writes
 		 */

drivers/md/dm-io.c

@@ -58,8 +58,7 @@ struct dm_io_client *dm_io_client_create(void)
 	if (!client->pool)
 		goto bad;
 
-	client->bios = bioset_create(min_ios, 0, (BIOSET_NEED_BVECS |
-						  BIOSET_NEED_RESCUER));
+	client->bios = bioset_create(min_ios, 0, BIOSET_NEED_BVECS);
 	if (!client->bios)
 		goto bad;
 

drivers/md/dm-kcopyd.c

@@ -477,8 +477,10 @@ static int run_complete_job(struct kcopyd_job *job)
 	 * If this is the master job, the sub jobs have already
 	 * completed so we can free everything.
 	 */
-	if (job->master_job == job)
+	if (job->master_job == job) {
+		mutex_destroy(&job->lock);
 		mempool_free(job, kc->job_pool);
+	}
 	fn(read_err, write_err, context);
 
 	if (atomic_dec_and_test(&kc->nr_jobs))
@@ -750,6 +752,7 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
 	 * followed by SPLIT_COUNT sub jobs.
 	 */
 	job = mempool_alloc(kc->job_pool, GFP_NOIO);
+	mutex_init(&job->lock);
 
 	/*
 	 * set up for the read.
@@ -811,7 +814,6 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
 	if (job->source.count <= SUB_JOB_SIZE)
 		dispatch_job(job);
 	else {
-		mutex_init(&job->lock);
 		job->progress = 0;
 		split_job(job);
 	}

drivers/md/dm-log-writes.c

@@ -594,7 +594,7 @@ static int log_mark(struct log_writes_c *lc, char *data)
 		return -ENOMEM;
 	}
 
-	block->data = kstrndup(data, maxsize, GFP_KERNEL);
+	block->data = kstrndup(data, maxsize - 1, GFP_KERNEL);
 	if (!block->data) {
 		DMERR("Error copying mark data");
 		kfree(block);

drivers/md/dm-mpath.c

@@ -64,36 +64,30 @@ struct priority_group {
 
 /* Multipath context */
 struct multipath {
-	struct list_head list;
-	struct dm_target *ti;
-
-	const char *hw_handler_name;
-	char *hw_handler_params;
+	unsigned long flags;		/* Multipath state flags */
 
 	spinlock_t lock;
-
-	unsigned nr_priority_groups;
-	struct list_head priority_groups;
-
-	wait_queue_head_t pg_init_wait;	/* Wait for pg_init completion */
+	enum dm_queue_mode queue_mode;
 
 	struct pgpath *current_pgpath;
 	struct priority_group *current_pg;
 	struct priority_group *next_pg;	/* Switch to this PG if set */
 
-	unsigned long flags;		/* Multipath state flags */
+	atomic_t nr_valid_paths;	/* Total number of usable paths */
+	unsigned nr_priority_groups;
+	struct list_head priority_groups;
 
+	const char *hw_handler_name;
+	char *hw_handler_params;
+	wait_queue_head_t pg_init_wait;	/* Wait for pg_init completion */
 	unsigned pg_init_retries;	/* Number of times to retry pg_init */
 	unsigned pg_init_delay_msecs;	/* Number of msecs before pg_init retry */
-
-	atomic_t nr_valid_paths;	/* Total number of usable paths */
 	atomic_t pg_init_in_progress;	/* Only one pg_init allowed at once */
 	atomic_t pg_init_count;		/* Number of times pg_init called */
 
-	enum dm_queue_mode queue_mode;
-
 	struct mutex work_mutex;
 	struct work_struct trigger_event;
+	struct dm_target *ti;
 
 	struct work_struct process_queued_bios;
 	struct bio_list queued_bios;
@@ -135,10 +129,10 @@ static struct pgpath *alloc_pgpath(void)
 {
 	struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
 
-	if (pgpath) {
+	if (!pgpath)
+		return NULL;
+
 	pgpath->is_active = true;
-		INIT_DELAYED_WORK(&pgpath->activate_path, activate_path_work);
-	}
 
 	return pgpath;
 }
@@ -193,13 +187,8 @@ static struct multipath *alloc_multipath(struct dm_target *ti)
 	if (m) {
 		INIT_LIST_HEAD(&m->priority_groups);
 		spin_lock_init(&m->lock);
-		set_bit(MPATHF_QUEUE_IO, &m->flags);
 		atomic_set(&m->nr_valid_paths, 0);
-		atomic_set(&m->pg_init_in_progress, 0);
-		atomic_set(&m->pg_init_count, 0);
-		m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
 		INIT_WORK(&m->trigger_event, trigger_event);
-		init_waitqueue_head(&m->pg_init_wait);
 		mutex_init(&m->work_mutex);
 
 		m->queue_mode = DM_TYPE_NONE;
@@ -221,14 +210,27 @@ static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
 			m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
 		else
 			m->queue_mode = DM_TYPE_REQUEST_BASED;
-	} else if (m->queue_mode == DM_TYPE_BIO_BASED) {
+
+	} else if (m->queue_mode == DM_TYPE_BIO_BASED ||
+		   m->queue_mode == DM_TYPE_NVME_BIO_BASED) {
 		INIT_WORK(&m->process_queued_bios, process_queued_bios);
+
+		if (m->queue_mode == DM_TYPE_BIO_BASED) {
 			/*
 			 * bio-based doesn't support any direct scsi_dh management;
 			 * it just discovers if a scsi_dh is attached.
 			 */
 			set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
 		}
+	}
+
+	if (m->queue_mode != DM_TYPE_NVME_BIO_BASED) {
+		set_bit(MPATHF_QUEUE_IO, &m->flags);
+		atomic_set(&m->pg_init_in_progress, 0);
+		atomic_set(&m->pg_init_count, 0);
+		m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
+		init_waitqueue_head(&m->pg_init_wait);
+	}
 
 	dm_table_set_type(ti->table, m->queue_mode);
 
@@ -246,6 +248,7 @@ static void free_multipath(struct multipath *m)
 
 	kfree(m->hw_handler_name);
 	kfree(m->hw_handler_params);
+	mutex_destroy(&m->work_mutex);
 	kfree(m);
 }
 
@@ -264,29 +267,23 @@ static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
 	return dm_per_bio_data(bio, multipath_per_bio_data_size());
 }
 
-static struct dm_bio_details *get_bio_details_from_bio(struct bio *bio)
+static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
 {
 	/* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
-	struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
 	void *bio_details = mpio + 1;
-
 	return bio_details;
 }
 
-static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p,
-					struct dm_bio_details **bio_details_p)
+static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
 {
 	struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
-	struct dm_bio_details *bio_details = get_bio_details_from_bio(bio);
-
-	memset(mpio, 0, sizeof(*mpio));
-	memset(bio_details, 0, sizeof(*bio_details));
-	dm_bio_record(bio_details, bio);
+	struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
 
-	if (mpio_p)
+	mpio->nr_bytes = bio->bi_iter.bi_size;
+	mpio->pgpath = NULL;
 	*mpio_p = mpio;
-	if (bio_details_p)
-		*bio_details_p = bio_details;
+
+	dm_bio_record(bio_details, bio);
 }
 
 /*-----------------------------------------------
@@ -340,6 +337,9 @@ static void __switch_pg(struct multipath *m, struct priority_group *pg)
 {
 	m->current_pg = pg;
 
+	if (m->queue_mode == DM_TYPE_NVME_BIO_BASED)
+		return;
+
 	/* Must we initialise the PG first, and queue I/O till it's ready? */
 	if (m->hw_handler_name) {
 		set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
@@ -385,6 +385,7 @@ static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
 	unsigned bypassed = 1;
 
 	if (!atomic_read(&m->nr_valid_paths)) {
+		if (m->queue_mode != DM_TYPE_NVME_BIO_BASED)
 			clear_bit(MPATHF_QUEUE_IO, &m->flags);
 		goto failed;
 	}
@@ -516,12 +517,10 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
 		return DM_MAPIO_KILL;
 	} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
 		   test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
-		if (pg_init_all_paths(m))
+		pg_init_all_paths(m);
 		return DM_MAPIO_DELAY_REQUEUE;
-		return DM_MAPIO_REQUEUE;
 	}
 
-	memset(mpio, 0, sizeof(*mpio));
 	mpio->pgpath = pgpath;
 	mpio->nr_bytes = nr_bytes;
 
@@ -530,11 +529,22 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
 	clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE, GFP_ATOMIC);
 	if (IS_ERR(clone)) {
 		/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
-		bool queue_dying = blk_queue_dying(q);
-		if (queue_dying) {
+		if (blk_queue_dying(q)) {
 			atomic_inc(&m->pg_init_in_progress);
 			activate_or_offline_path(pgpath);
+			return DM_MAPIO_DELAY_REQUEUE;
 		}
+
+		/*
+		 * blk-mq's SCHED_RESTART can cover this requeue, so we
+		 * needn't deal with it by DELAY_REQUEUE. More importantly,
+		 * we have to return DM_MAPIO_REQUEUE so that blk-mq can
+		 * get the queue busy feedback (via BLK_STS_RESOURCE),
+		 * otherwise I/O merging can suffer.
+		 */
+		if (q->mq_ops)
+			return DM_MAPIO_REQUEUE;
+		else
 			return DM_MAPIO_DELAY_REQUEUE;
 	}
 	clone->bio = clone->biotail = NULL;
@@ -557,9 +567,9 @@ static void multipath_release_clone(struct request *clone)
 /*
  * Map cloned bios (bio-based multipath)
  */
-static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)
+
+static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
 {
-	size_t nr_bytes = bio->bi_iter.bi_size;
 	struct pgpath *pgpath;
 	unsigned long flags;
 	bool queue_io;
@@ -568,7 +578,7 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
 	pgpath = READ_ONCE(m->current_pgpath);
 	queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
 	if (!pgpath || !queue_io)
-		pgpath = choose_pgpath(m, nr_bytes);
+		pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
 
 	if ((pgpath && queue_io) ||
 	    (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
@@ -576,14 +586,62 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
 		spin_lock_irqsave(&m->lock, flags);
 		bio_list_add(&m->queued_bios, bio);
 		spin_unlock_irqrestore(&m->lock, flags);
+
 		/* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
 		if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
 			pg_init_all_paths(m);
 		else if (!queue_io)
 			queue_work(kmultipathd, &m->process_queued_bios);
-		return DM_MAPIO_SUBMITTED;
+
+		return ERR_PTR(-EAGAIN);
+	}
+
+	return pgpath;
+}
+
+static struct pgpath *__map_bio_nvme(struct multipath *m, struct bio *bio)
+{
+	struct pgpath *pgpath;
+	unsigned long flags;
+
+	/* Do we need to select a new pgpath? */
+	/*
+	 * FIXME: currently only switching path if no path (due to failure, etc)
+	 * - which negates the point of using a path selector
+	 */
+	pgpath = READ_ONCE(m->current_pgpath);
+	if (!pgpath)
+		pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
+
+	if (!pgpath) {
+		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
+			/* Queue for the daemon to resubmit */
+			spin_lock_irqsave(&m->lock, flags);
+			bio_list_add(&m->queued_bios, bio);
+			spin_unlock_irqrestore(&m->lock, flags);
+			queue_work(kmultipathd, &m->process_queued_bios);
+
+			return ERR_PTR(-EAGAIN);
+		}
+		return NULL;
 	}
 
+	return pgpath;
+}
+
+static int __multipath_map_bio(struct multipath *m, struct bio *bio,
+			       struct dm_mpath_io *mpio)
+{
+	struct pgpath *pgpath;
+
+	if (m->queue_mode == DM_TYPE_NVME_BIO_BASED)
+		pgpath = __map_bio_nvme(m, bio);
+	else
+		pgpath = __map_bio(m, bio);
+
+	if (IS_ERR(pgpath))
+		return DM_MAPIO_SUBMITTED;
+
 	if (!pgpath) {
 		if (must_push_back_bio(m))
 			return DM_MAPIO_REQUEUE;
@@ -592,7 +650,6 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
 	}
 
 	mpio->pgpath = pgpath;
-	mpio->nr_bytes = nr_bytes;
 
 	bio->bi_status = 0;
 	bio_set_dev(bio, pgpath->path.dev->bdev);
@@ -601,7 +658,7 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
 	if (pgpath->pg->ps.type->start_io)
 		pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
 					      &pgpath->path,
-					      nr_bytes);
+					      mpio->nr_bytes);
 	return DM_MAPIO_REMAPPED;
 }
 
@@ -610,8 +667,7 @@ static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
 	struct multipath *m = ti->private;
 	struct dm_mpath_io *mpio = NULL;
 
-	multipath_init_per_bio_data(bio, &mpio, NULL);
-
+	multipath_init_per_bio_data(bio, &mpio);
 	return __multipath_map_bio(m, bio, mpio);
 }
 
@@ -619,7 +675,8 @@ static void process_queued_io_list(struct multipath *m)
 {
 	if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
 		dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
-	else if (m->queue_mode == DM_TYPE_BIO_BASED)
+	else if (m->queue_mode == DM_TYPE_BIO_BASED ||
+		 m->queue_mode == DM_TYPE_NVME_BIO_BASED)
 		queue_work(kmultipathd, &m->process_queued_bios);
 }
 
@@ -649,7 +706,9 @@ static void process_queued_bios(struct work_struct *work)
 
 	blk_start_plug(&plug);
 	while ((bio = bio_list_pop(&bios))) {
-		r = __multipath_map_bio(m, bio, get_mpio_from_bio(bio));
+		struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
+		dm_bio_restore(get_bio_details_from_mpio(mpio), bio);
+		r = __multipath_map_bio(m, bio, mpio);
 		switch (r) {
 		case DM_MAPIO_KILL:
 			bio->bi_status = BLK_STS_IOERR;
@@ -752,34 +811,11 @@ static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
 	return 0;
 }
 
-static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
-			       struct dm_target *ti)
+static int setup_scsi_dh(struct block_device *bdev, struct multipath *m, char **error)
 {
-	int r;
-	struct pgpath *p;
-	struct multipath *m = ti->private;
-	struct request_queue *q = NULL;
+	struct request_queue *q = bdev_get_queue(bdev);
 	const char *attached_handler_name;
-
-	/* we need at least a path arg */
-	if (as->argc < 1) {
-		ti->error = "no device given";
-		return ERR_PTR(-EINVAL);
-	}
-
-	p = alloc_pgpath();
-	if (!p)
-		return ERR_PTR(-ENOMEM);
-
-	r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
-			  &p->path.dev);
-	if (r) {
-		ti->error = "error getting device";
-		goto bad;
-	}
-
-	if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) || m->hw_handler_name)
-		q = bdev_get_queue(p->path.dev->bdev);
+	int r;
 
 	if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
 retain:
@@ -811,23 +847,56 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps
 			char b[BDEVNAME_SIZE];
 
 			printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
-				bdevname(p->path.dev->bdev, b));
+			       bdevname(bdev, b));
 			goto retain;
 		}
 		if (r < 0) {
-			ti->error = "error attaching hardware handler";
-			dm_put_device(ti, p->path.dev);
-			goto bad;
+			*error = "error attaching hardware handler";
+			return r;
 		}
 
 		if (m->hw_handler_params) {
 			r = scsi_dh_set_params(q, m->hw_handler_params);
 			if (r < 0) {
-				ti->error = "unable to set hardware "
-							"handler parameters";
-				dm_put_device(ti, p->path.dev);
+				*error = "unable to set hardware handler parameters";
+				return r;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
+				 struct dm_target *ti)
+{
+	int r;
+	struct pgpath *p;
+	struct multipath *m = ti->private;
+
+	/* we need at least a path arg */
+	if (as->argc < 1) {
+		ti->error = "no device given";
+		return ERR_PTR(-EINVAL);
+	}
+
+	p = alloc_pgpath();
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+
+	r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
+			  &p->path.dev);
+	if (r) {
+		ti->error = "error getting device";
 		goto bad;
 	}
+
+	if (m->queue_mode != DM_TYPE_NVME_BIO_BASED) {
+		INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
+		r = setup_scsi_dh(p->path.dev->bdev, m, &ti->error);
+		if (r) {
+			dm_put_device(ti, p->path.dev);
+			goto bad;
 		}
 	}
 
@@ -838,7 +907,6 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps
 	}
 
 	return p;
-
  bad:
 	free_pgpath(p);
 	return ERR_PTR(r);
@@ -933,7 +1001,8 @@ static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
 	if (!hw_argc)
 		return 0;
 
-	if (m->queue_mode == DM_TYPE_BIO_BASED) {
+	if (m->queue_mode == DM_TYPE_BIO_BASED ||
+	    m->queue_mode == DM_TYPE_NVME_BIO_BASED) {
 		dm_consume_args(as, hw_argc);
 		DMERR("bio-based multipath doesn't allow hardware handler args");
 		return 0;
@@ -1022,6 +1091,8 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m)
 
 			if (!strcasecmp(queue_mode_name, "bio"))
 				m->queue_mode = DM_TYPE_BIO_BASED;
+			else if (!strcasecmp(queue_mode_name, "nvme"))
+				m->queue_mode = DM_TYPE_NVME_BIO_BASED;
 			else if (!strcasecmp(queue_mode_name, "rq"))
 				m->queue_mode = DM_TYPE_REQUEST_BASED;
 			else if (!strcasecmp(queue_mode_name, "mq"))
@@ -1122,7 +1193,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	ti->num_discard_bios = 1;
 	ti->num_write_same_bios = 1;
 	ti->num_write_zeroes_bios = 1;
-	if (m->queue_mode == DM_TYPE_BIO_BASED)
+	if (m->queue_mode == DM_TYPE_BIO_BASED || m->queue_mode == DM_TYPE_NVME_BIO_BASED)
 		ti->per_io_data_size = multipath_per_bio_data_size();
 	else
 		ti->per_io_data_size = sizeof(struct dm_mpath_io);
@@ -1151,16 +1222,19 @@ static void multipath_wait_for_pg_init_completion(struct multipath *m)
 
 static void flush_multipath_work(struct multipath *m)
 {
+	if (m->hw_handler_name) {
 		set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
 		smp_mb__after_atomic();
 
 		flush_workqueue(kmpath_handlerd);
 		multipath_wait_for_pg_init_completion(m);
-	flush_workqueue(kmultipathd);
-	flush_work(&m->trigger_event);
 
 		clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
 		smp_mb__after_atomic();
+	}
+
+	flush_workqueue(kmultipathd);
+	flush_work(&m->trigger_event);
 }
 
 static void multipath_dtr(struct dm_target *ti)
@@ -1496,6 +1570,9 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
 	if (error && blk_path_error(error)) {
 		struct multipath *m = ti->private;
 
+		if (error == BLK_STS_RESOURCE)
+			r = DM_ENDIO_DELAY_REQUEUE;
+		else
 			r = DM_ENDIO_REQUEUE;
 
 		if (pgpath)
@@ -1546,9 +1623,6 @@ static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
 		goto done;
 	}
 
-	/* Queue for the daemon to resubmit */
-	dm_bio_restore(get_bio_details_from_bio(clone), clone);
-
 	spin_lock_irqsave(&m->lock, flags);
 	bio_list_add(&m->queued_bios, clone);
 	spin_unlock_irqrestore(&m->lock, flags);
@@ -1656,6 +1730,9 @@ static void multipath_status(struct dm_target *ti, status_type_t type,
 			case DM_TYPE_BIO_BASED:
 				DMEMIT("queue_mode bio ");
 				break;
+			case DM_TYPE_NVME_BIO_BASED:
+				DMEMIT("queue_mode nvme ");
+				break;
 			case DM_TYPE_MQ_REQUEST_BASED:
 				DMEMIT("queue_mode mq ");
 				break;

drivers/md/dm-queue-length.c

@@ -195,9 +195,6 @@ static struct dm_path *ql_select_path(struct path_selector *ps, size_t nr_bytes)
 	if (list_empty(&s->valid_paths))
 		goto out;
 
-	/* Change preferred (first in list) path to evenly balance. */
-	list_move_tail(s->valid_paths.next, &s->valid_paths);
-
 	list_for_each_entry(pi, &s->valid_paths, list) {
 		if (!best ||
 		    (atomic_read(&pi->qlen) < atomic_read(&best->qlen)))
@@ -210,6 +207,9 @@ static struct dm_path *ql_select_path(struct path_selector *ps, size_t nr_bytes)
 	if (!best)
 		goto out;
 
+	/* Move most recently used to least preferred to evenly balance. */
+	list_move_tail(&best->list, &s->valid_paths);
+
 	ret = best->path;
 out:
 	spin_unlock_irqrestore(&s->lock, flags);

drivers/md/dm-raid.c

@@ -29,6 +29,9 @@
  */
 #define	MIN_RAID456_JOURNAL_SPACE (4*2048)
 
+/* Global list of all raid sets */
+static LIST_HEAD(raid_sets);
+
 static bool devices_handle_discard_safely = false;
 
 /*
@@ -105,8 +108,6 @@ struct raid_dev {
 #define CTR_FLAG_JOURNAL_DEV		(1 << __CTR_FLAG_JOURNAL_DEV)
 #define CTR_FLAG_JOURNAL_MODE		(1 << __CTR_FLAG_JOURNAL_MODE)
 
-#define RESUME_STAY_FROZEN_FLAGS (CTR_FLAG_DELTA_DISKS | CTR_FLAG_DATA_OFFSET)
-
 /*
  * Definitions of various constructor flags to
  * be used in checks of valid / invalid flags
@@ -209,6 +210,8 @@ struct raid_dev {
 #define RT_FLAG_UPDATE_SBS		3
 #define RT_FLAG_RESHAPE_RS		4
 #define RT_FLAG_RS_SUSPENDED		5
+#define RT_FLAG_RS_IN_SYNC		6
+#define RT_FLAG_RS_RESYNCING		7
 
 /* Array elements of 64 bit needed for rebuild/failed disk bits */
 #define DISKS_ARRAY_ELEMS ((MAX_RAID_DEVICES + (sizeof(uint64_t) * 8 - 1)) / sizeof(uint64_t) / 8)
@@ -224,8 +227,8 @@ struct rs_layout {
 
 struct raid_set {
 	struct dm_target *ti;
+	struct list_head list;
 
-	uint32_t bitmap_loaded;
 	uint32_t stripe_cache_entries;
 	unsigned long ctr_flags;
 	unsigned long runtime_flags;
@@ -270,6 +273,19 @@ static void rs_config_restore(struct raid_set *rs, struct rs_layout *l)
 	mddev->new_chunk_sectors = l->new_chunk_sectors;
 }
 
+/* Find any raid_set in active slot for @rs on global list */
+static struct raid_set *rs_find_active(struct raid_set *rs)
+{
+	struct raid_set *r;
+	struct mapped_device *md = dm_table_get_md(rs->ti->table);
+
+	list_for_each_entry(r, &raid_sets, list)
+		if (r != rs && dm_table_get_md(r->ti->table) == md)
+			return r;
+
+	return NULL;
+}
+
 /* raid10 algorithms (i.e. formats) */
 #define	ALGORITHM_RAID10_DEFAULT	0
 #define	ALGORITHM_RAID10_NEAR		1
@@ -572,7 +588,7 @@ static const char *raid10_md_layout_to_format(int layout)
 }
 
 /* Return md raid10 algorithm for @name */
-static int raid10_name_to_format(const char *name)
+static const int raid10_name_to_format(const char *name)
 {
 	if (!strcasecmp(name, "near"))
 		return ALGORITHM_RAID10_NEAR;
@@ -675,15 +691,11 @@ static struct raid_type *get_raid_type_by_ll(const int level, const int layout)
 	return NULL;
 }
 
-/*
- * Conditionally change bdev capacity of @rs
- * in case of a disk add/remove reshape
- */
-static void rs_set_capacity(struct raid_set *rs)
+/* Adjust rdev sectors */
+static void rs_set_rdev_sectors(struct raid_set *rs)
 {
 	struct mddev *mddev = &rs->md;
 	struct md_rdev *rdev;
-	struct gendisk *gendisk = dm_disk(dm_table_get_md(rs->ti->table));
 
 	/*
 	 * raid10 sets rdev->sector to the device size, which
@@ -692,8 +704,16 @@ static void rs_set_capacity(struct raid_set *rs)
 	rdev_for_each(rdev, mddev)
 		if (!test_bit(Journal, &rdev->flags))
 			rdev->sectors = mddev->dev_sectors;
+}
 
-	set_capacity(gendisk, mddev->array_sectors);
+/*
+ * Change bdev capacity of @rs in case of a disk add/remove reshape
+ */
+static void rs_set_capacity(struct raid_set *rs)
+{
+	struct gendisk *gendisk = dm_disk(dm_table_get_md(rs->ti->table));
+
+	set_capacity(gendisk, rs->md.array_sectors);
 	revalidate_disk(gendisk);
 }
 
@@ -744,6 +764,7 @@ static struct raid_set *raid_set_alloc(struct dm_target *ti, struct raid_type *r
 
 	mddev_init(&rs->md);
 
+	INIT_LIST_HEAD(&rs->list);
 	rs->raid_disks = raid_devs;
 	rs->delta_disks = 0;
 
@@ -761,6 +782,9 @@ static struct raid_set *raid_set_alloc(struct dm_target *ti, struct raid_type *r
 	for (i = 0; i < raid_devs; i++)
 		md_rdev_init(&rs->dev[i].rdev);
 
+	/* Add @rs to global list. */
+	list_add(&rs->list, &raid_sets);
+
 	/*
 	 * Remaining items to be initialized by further RAID params:
 	 *  rs->md.persistent
@@ -773,6 +797,7 @@ static struct raid_set *raid_set_alloc(struct dm_target *ti, struct raid_type *r
 	return rs;
 }
 
+/* Free all @rs allocations and remove it from global list. */
 static void raid_set_free(struct raid_set *rs)
 {
 	int i;
@@ -790,6 +815,8 @@ static void raid_set_free(struct raid_set *rs)
 			dm_put_device(rs->ti, rs->dev[i].data_dev);
 	}
 
+	list_del(&rs->list);
+
 	kfree(rs);
 }
 
@@ -1002,7 +1029,7 @@ static int validate_raid_redundancy(struct raid_set *rs)
 		    !rs->dev[i].rdev.sb_page)
 			rebuild_cnt++;
 
-	switch (rs->raid_type->level) {
+	switch (rs->md.level) {
 	case 0:
 		break;
 	case 1:
@@ -1017,6 +1044,11 @@ static int validate_raid_redundancy(struct raid_set *rs)
 		break;
 	case 10:
 		copies = raid10_md_layout_to_copies(rs->md.new_layout);
+		if (copies < 2) {
+			DMERR("Bogus raid10 data copies < 2!");
+			return -EINVAL;
+		}
+
 		if (rebuild_cnt < copies)
 			break;
 
@@ -1576,6 +1608,24 @@ static sector_t __rdev_sectors(struct raid_set *rs)
 	return 0;
 }
 
+/* Check that calculated dev_sectors fits all component devices. */
+static int _check_data_dev_sectors(struct raid_set *rs)
+{
+	sector_t ds = ~0;
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, &rs->md)
+		if (!test_bit(Journal, &rdev->flags) && rdev->bdev) {
+			ds = min(ds, to_sector(i_size_read(rdev->bdev->bd_inode)));
+			if (ds < rs->md.dev_sectors) {
+				rs->ti->error = "Component device(s) too small";
+				return -EINVAL;
+			}
+		}
+
+	return 0;
+}
+
 /* Calculate the sectors per device and per array used for @rs */
 static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
 {
@@ -1625,7 +1675,7 @@ static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
 	mddev->array_sectors = array_sectors;
 	mddev->dev_sectors = dev_sectors;
 
-	return 0;
+	return _check_data_dev_sectors(rs);
 bad:
 	rs->ti->error = "Target length not divisible by number of data devices";
 	return -EINVAL;
@@ -1674,8 +1724,11 @@ static void do_table_event(struct work_struct *ws)
 	struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);
 
 	smp_rmb(); /* Make sure we access most actual mddev properties */
-	if (!rs_is_reshaping(rs))
+	if (!rs_is_reshaping(rs)) {
+		if (rs_is_raid10(rs))
+			rs_set_rdev_sectors(rs);
 		rs_set_capacity(rs);
+	}
 	dm_table_event(rs->ti->table);
 }
 
@@ -1860,7 +1913,7 @@ static bool rs_reshape_requested(struct raid_set *rs)
 	if (rs_takeover_requested(rs))
 		return false;
 
-	if (!mddev->level)
+	if (rs_is_raid0(rs))
 		return false;
 
 	change = mddev->new_layout != mddev->layout ||
@@ -1868,7 +1921,7 @@ static bool rs_reshape_requested(struct raid_set *rs)
 		 rs->delta_disks;
 
 	/* Historical case to support raid1 reshape without delta disks */
-	if (mddev->level == 1) {
+	if (rs_is_raid1(rs)) {
 		if (rs->delta_disks)
 			return !!rs->delta_disks;
 
@@ -1876,7 +1929,7 @@ static bool rs_reshape_requested(struct raid_set *rs)
 		       mddev->raid_disks != rs->raid_disks;
 	}
 
-	if (mddev->level == 10)
+	if (rs_is_raid10(rs))
 		return change &&
 		       !__is_raid10_far(mddev->new_layout) &&
 		       rs->delta_disks >= 0;
@@ -2340,7 +2393,7 @@ static int super_init_validation(struct raid_set *rs, struct md_rdev *rdev)
 			DMERR("new device%s provided without 'rebuild'",
 			      new_devs > 1 ? "s" : "");
 			return -EINVAL;
-		} else if (rs_is_recovering(rs)) {
+		} else if (!test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags) && rs_is_recovering(rs)) {
 			DMERR("'rebuild' specified while raid set is not in-sync (recovery_cp=%llu)",
 			      (unsigned long long) mddev->recovery_cp);
 			return -EINVAL;
@@ -2640,12 +2693,19 @@ static int rs_adjust_data_offsets(struct raid_set *rs)
 	 * Make sure we got a minimum amount of free sectors per device
 	 */
 	if (rs->data_offset &&
-	    to_sector(i_size_read(rdev->bdev->bd_inode)) - rdev->sectors < MIN_FREE_RESHAPE_SPACE) {
+	    to_sector(i_size_read(rdev->bdev->bd_inode)) - rs->md.dev_sectors < MIN_FREE_RESHAPE_SPACE) {
 		rs->ti->error = data_offset ? "No space for forward reshape" :
 					      "No space for backward reshape";
 		return -ENOSPC;
 	}
 out:
+	/*
+	 * Raise recovery_cp in case data_offset != 0 to
+	 * avoid false recovery positives in the constructor.
+	 */
+	if (rs->md.recovery_cp < rs->md.dev_sectors)
+		rs->md.recovery_cp += rs->dev[0].rdev.data_offset;
+
 	/* Adjust data offsets on all rdevs but on any raid4/5/6 journal device */
 	rdev_for_each(rdev, &rs->md) {
 		if (!test_bit(Journal, &rdev->flags)) {
@@ -2682,14 +2742,14 @@ static int rs_setup_takeover(struct raid_set *rs)
 	sector_t new_data_offset = rs->dev[0].rdev.data_offset ? 0 : rs->data_offset;
 
 	if (rt_is_raid10(rs->raid_type)) {
-		if (mddev->level == 0) {
+		if (rs_is_raid0(rs)) {
 			/* Userpace reordered disks -> adjust raid_disk indexes */
 			__reorder_raid_disk_indexes(rs);
 
 			/* raid0 -> raid10_far layout */
 			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_FAR,
 								   rs->raid10_copies);
-		} else if (mddev->level == 1)
+		} else if (rs_is_raid1(rs))
 			/* raid1 -> raid10_near layout */
 			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
 								   rs->raid_disks);
@@ -2777,6 +2837,23 @@ static int rs_prepare_reshape(struct raid_set *rs)
 	return 0;
 }
 
+/* Get reshape sectors from data_offsets or raid set */
+static sector_t _get_reshape_sectors(struct raid_set *rs)
+{
+	struct md_rdev *rdev;
+	sector_t reshape_sectors = 0;
+
+	rdev_for_each(rdev, &rs->md)
+		if (!test_bit(Journal, &rdev->flags)) {
+			reshape_sectors = (rdev->data_offset > rdev->new_data_offset) ?
+					rdev->data_offset - rdev->new_data_offset :
+					rdev->new_data_offset - rdev->data_offset;
+			break;
+		}
+
+	return max(reshape_sectors, (sector_t) rs->data_offset);
+}
+
 /*
  *
  * - change raid layout
@@ -2788,6 +2865,7 @@ static int rs_setup_reshape(struct raid_set *rs)
 {
 	int r = 0;
 	unsigned int cur_raid_devs, d;
+	sector_t reshape_sectors = _get_reshape_sectors(rs);
 	struct mddev *mddev = &rs->md;
 	struct md_rdev *rdev;
 
@@ -2804,13 +2882,13 @@ static int rs_setup_reshape(struct raid_set *rs)
 	/*
 	 * Adjust array size:
 	 *
-	 * - in case of adding disks, array size has
+	 * - in case of adding disk(s), array size has
 	 *   to grow after the disk adding reshape,
 	 *   which'll hapen in the event handler;
 	 *   reshape will happen forward, so space has to
 	 *   be available at the beginning of each disk
 	 *
-	 * - in case of removing disks, array size
+	 * - in case of removing disk(s), array size
 	 *   has to shrink before starting the reshape,
 	 *   which'll happen here;
 	 *   reshape will happen backward, so space has to
@@ -2841,7 +2919,7 @@ static int rs_setup_reshape(struct raid_set *rs)
 			rdev->recovery_offset = rs_is_raid1(rs) ? 0 : MaxSector;
 		}
 
-		mddev->reshape_backwards = 0; /* adding disks -> forward reshape */
+		mddev->reshape_backwards = 0; /* adding disk(s) -> forward reshape */
 
 	/* Remove disk(s) */
 	} else if (rs->delta_disks < 0) {
@@ -2874,6 +2952,15 @@ static int rs_setup_reshape(struct raid_set *rs)
 		mddev->reshape_backwards = rs->dev[0].rdev.data_offset ? 0 : 1;
 	}
 
+	/*
+	 * Adjust device size for forward reshape
+	 * because md_finish_reshape() reduces it.
+	 */
+	if (!mddev->reshape_backwards)
+		rdev_for_each(rdev, &rs->md)
+			if (!test_bit(Journal, &rdev->flags))
+				rdev->sectors += reshape_sectors;
+
 	return r;
 }
 
@@ -2890,7 +2977,7 @@ static void configure_discard_support(struct raid_set *rs)
 	/*
 	 * XXX: RAID level 4,5,6 require zeroing for safety.
 	 */
-	raid456 = (rs->md.level == 4 || rs->md.level == 5 || rs->md.level == 6);
+	raid456 = rs_is_raid456(rs);
 
 	for (i = 0; i < rs->raid_disks; i++) {
 		struct request_queue *q;
@@ -2915,7 +3002,7 @@ static void configure_discard_support(struct raid_set *rs)
 	 * RAID1 and RAID10 personalities require bio splitting,
 	 * RAID0/4/5/6 don't and process large discard bios properly.
 	 */
-	ti->split_discard_bios = !!(rs->md.level == 1 || rs->md.level == 10);
+	ti->split_discard_bios = !!(rs_is_raid1(rs) || rs_is_raid10(rs));
 	ti->num_discard_bios = 1;
 }
 
@@ -2935,10 +3022,10 @@ static void configure_discard_support(struct raid_set *rs)
 static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
 	int r;
-	bool resize;
+	bool resize = false;
 	struct raid_type *rt;
 	unsigned int num_raid_params, num_raid_devs;
-	sector_t calculated_dev_sectors, rdev_sectors;
+	sector_t calculated_dev_sectors, rdev_sectors, reshape_sectors;
 	struct raid_set *rs = NULL;
 	const char *arg;
 	struct rs_layout rs_layout;
@@ -3021,7 +3108,10 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad;
 	}
 
-	resize = calculated_dev_sectors != rdev_sectors;
+
+	reshape_sectors = _get_reshape_sectors(rs);
+	if (calculated_dev_sectors != rdev_sectors)
+		resize = calculated_dev_sectors != (reshape_sectors ? rdev_sectors - reshape_sectors : rdev_sectors);
 
 	INIT_WORK(&rs->md.event_work, do_table_event);
 	ti->private = rs;
@@ -3105,6 +3195,8 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 			goto bad;
 		}
 
+		/* Out-of-place space has to be available to allow for a reshape unless raid1! */
+		if (reshape_sectors || rs_is_raid1(rs)) {
 			/*
 			  * We can only prepare for a reshape here, because the
 			  * raid set needs to run to provide the repective reshape
@@ -3118,6 +3210,7 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 			/* Reshaping ain't recovery, so disable recovery */
 			rs_setup_recovery(rs, MaxSector);
+		}
 		rs_set_cur(rs);
 	} else {
 		/* May not set recovery when a device rebuild is requested */
@@ -3144,7 +3237,6 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	mddev_lock_nointr(&rs->md);
 	r = md_run(&rs->md);
 	rs->md.in_sync = 0; /* Assume already marked dirty */
-
 	if (r) {
 		ti->error = "Failed to run raid array";
 		mddev_unlock(&rs->md);
@@ -3248,25 +3340,27 @@ static int raid_map(struct dm_target *ti, struct bio *bio)
 }
 
 /* Return string describing the current sync action of @mddev */
-static const char *decipher_sync_action(struct mddev *mddev)
+static const char *decipher_sync_action(struct mddev *mddev, unsigned long recovery)
 {
-	if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+	if (test_bit(MD_RECOVERY_FROZEN, &recovery))
 		return "frozen";
 
-	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
-	    (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
-		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+	/* The MD sync thread can be done with io but still be running */
+	if (!test_bit(MD_RECOVERY_DONE, &recovery) &&
+	    (test_bit(MD_RECOVERY_RUNNING, &recovery) ||
+	     (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &recovery)))) {
+		if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
 			return "reshape";
 
-		if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
-			if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+		if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
+			if (!test_bit(MD_RECOVERY_REQUESTED, &recovery))
 				return "resync";
-			else if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
+			else if (test_bit(MD_RECOVERY_CHECK, &recovery))
 				return "check";
 			return "repair";
 		}
 
-		if (test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
+		if (test_bit(MD_RECOVERY_RECOVER, &recovery))
 			return "recover";
 	}
 
@@ -3283,7 +3377,7 @@ static const char *decipher_sync_action(struct mddev *mddev)
  *  'A' = Alive and in-sync raid set component _or_ alive raid4/5/6 'write_through' journal device
  *  '-' = Non-existing device (i.e. uspace passed '- -' into the ctr)
  */
-static const char *__raid_dev_status(struct raid_set *rs, struct md_rdev *rdev, bool array_in_sync)
+static const char *__raid_dev_status(struct raid_set *rs, struct md_rdev *rdev)
 {
 	if (!rdev->bdev)
 		return "-";
@@ -3291,85 +3385,108 @@ static const char *__raid_dev_status(struct raid_set *rs, struct md_rdev *rdev,
 		return "D";
 	else if (test_bit(Journal, &rdev->flags))
 		return (rs->journal_dev.mode == R5C_JOURNAL_MODE_WRITE_THROUGH) ? "A" : "a";
-	else if (!array_in_sync || !test_bit(In_sync, &rdev->flags))
+	else if (test_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags) ||
+		 (!test_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags) &&
+		  !test_bit(In_sync, &rdev->flags)))
 		return "a";
 	else
 		return "A";
 }
 
-/* Helper to return resync/reshape progress for @rs and @array_in_sync */
-static sector_t rs_get_progress(struct raid_set *rs,
-				sector_t resync_max_sectors, bool *array_in_sync)
+/* Helper to return resync/reshape progress for @rs and runtime flags for raid set in sync / resynching */
+static sector_t rs_get_progress(struct raid_set *rs, unsigned long recovery,
+				sector_t resync_max_sectors)
 {
-	sector_t r, curr_resync_completed;
+	sector_t r;
 	struct mddev *mddev = &rs->md;
 
-	curr_resync_completed = mddev->curr_resync_completed ?: mddev->recovery_cp;
-	*array_in_sync = false;
+	clear_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+	clear_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);
 
 	if (rs_is_raid0(rs)) {
 		r = resync_max_sectors;
-		*array_in_sync = true;
-
-	} else {
-		r = mddev->reshape_position;
+		set_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
 
-		/* Reshape is relative to the array size */
-		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) ||
-		    r != MaxSector) {
-			if (r == MaxSector) {
-				*array_in_sync = true;
-				r = resync_max_sectors;
 	} else {
-				/* Got to reverse on backward reshape */
-				if (mddev->reshape_backwards)
-					r = mddev->array_sectors - r;
-
-				/* Devide by # of data stripes */
-				sector_div(r, mddev_data_stripes(rs));
-			}
-
-		/* Sync is relative to the component device size */
-		} else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
-			r = curr_resync_completed;
+		if (test_bit(MD_RECOVERY_NEEDED, &recovery) ||
+		    test_bit(MD_RECOVERY_RESHAPE, &recovery) ||
+		    test_bit(MD_RECOVERY_RUNNING, &recovery))
+			r = mddev->curr_resync_completed;
 		else
 			r = mddev->recovery_cp;
 
-		if ((r == MaxSector) ||
-		    (test_bit(MD_RECOVERY_DONE, &mddev->recovery) &&
-		     (mddev->curr_resync_completed == resync_max_sectors))) {
+		if (r >= resync_max_sectors &&
+		    (!test_bit(MD_RECOVERY_REQUESTED, &recovery) ||
+		     (!test_bit(MD_RECOVERY_FROZEN, &recovery) &&
+		      !test_bit(MD_RECOVERY_NEEDED, &recovery) &&
+		      !test_bit(MD_RECOVERY_RUNNING, &recovery)))) {
 			/*
 			 * Sync complete.
 			 */
-			*array_in_sync = true;
-			r = resync_max_sectors;
-		} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+			/* In case we have finished recovering, the array is in sync. */
+			if (test_bit(MD_RECOVERY_RECOVER, &recovery))
+				set_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+
+		} else if (test_bit(MD_RECOVERY_RECOVER, &recovery)) {
+			/*
+			 * In case we are recovering, the array is not in sync
+			 * and health chars should show the recovering legs.
+			 */
+			;
+
+		} else if (test_bit(MD_RECOVERY_SYNC, &recovery) &&
+			   !test_bit(MD_RECOVERY_REQUESTED, &recovery)) {
+			/*
+			 * If "resync" is occurring, the raid set
+			 * is or may be out of sync hence the health
+			 * characters shall be 'a'.
+			 */
+			set_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);
+
+		} else if (test_bit(MD_RECOVERY_RESHAPE, &recovery) &&
+			   !test_bit(MD_RECOVERY_REQUESTED, &recovery)) {
+			/*
+			 * If "reshape" is occurring, the raid set
+			 * is or may be out of sync hence the health
+			 * characters shall be 'a'.
+			 */
+			set_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);
+
+		} else if (test_bit(MD_RECOVERY_REQUESTED, &recovery)) {
 			/*
 			 * If "check" or "repair" is occurring, the raid set has
 			 * undergone an initial sync and the health characters
 			 * should not be 'a' anymore.
 			 */
-			*array_in_sync = true;
+			set_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+
 		} else {
 			struct md_rdev *rdev;
 
+			/*
+			 * We are idle and recovery is needed, prevent 'A' chars race
+			 * caused by components still set to in-sync by constrcuctor.
+			 */
+			if (test_bit(MD_RECOVERY_NEEDED, &recovery))
+				set_bit(RT_FLAG_RS_RESYNCING, &rs->runtime_flags);
+
 			/*
 			 * The raid set may be doing an initial sync, or it may
 			 * be rebuilding individual components.	 If all the
 			 * devices are In_sync, then it is the raid set that is
 			 * being initialized.
 			 */
+			set_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
 			rdev_for_each(rdev, mddev)
 				if (!test_bit(Journal, &rdev->flags) &&
-				    !test_bit(In_sync, &rdev->flags))
-					*array_in_sync = true;
-#if 0
-			r = 0; /* HM FIXME: TESTME: https://bugzilla.redhat.com/show_bug.cgi?id=1210637 ? */
-#endif
+				    !test_bit(In_sync, &rdev->flags)) {
+					clear_bit(RT_FLAG_RS_IN_SYNC, &rs->runtime_flags);
+					break;
+				}
 		}
 	}
 
-	return r;
+	return min(r, resync_max_sectors);
 }
 
 /* Helper to return @dev name or "-" if !@dev */
@@ -3385,7 +3502,7 @@ static void raid_status(struct dm_target *ti, status_type_t type,
 	struct mddev *mddev = &rs->md;
 	struct r5conf *conf = mddev->private;
 	int i, max_nr_stripes = conf ? conf->max_nr_stripes : 0;
-	bool array_in_sync;
+	unsigned long recovery;
 	unsigned int raid_param_cnt = 1; /* at least 1 for chunksize */
 	unsigned int sz = 0;
 	unsigned int rebuild_disks;
@@ -3405,17 +3522,18 @@ static void raid_status(struct dm_target *ti, status_type_t type,
 
 		/* Access most recent mddev properties for status output */
 		smp_rmb();
+		recovery = rs->md.recovery;
 		/* Get sensible max sectors even if raid set not yet started */
 		resync_max_sectors = test_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags) ?
 				      mddev->resync_max_sectors : mddev->dev_sectors;
-		progress = rs_get_progress(rs, resync_max_sectors, &array_in_sync);
+		progress = rs_get_progress(rs, recovery, resync_max_sectors);
 		resync_mismatches = (mddev->last_sync_action && !strcasecmp(mddev->last_sync_action, "check")) ?
 				    atomic64_read(&mddev->resync_mismatches) : 0;
-		sync_action = decipher_sync_action(&rs->md);
+		sync_action = decipher_sync_action(&rs->md, recovery);
 
 		/* HM FIXME: do we want another state char for raid0? It shows 'D'/'A'/'-' now */
 		for (i = 0; i < rs->raid_disks; i++)
-			DMEMIT(__raid_dev_status(rs, &rs->dev[i].rdev, array_in_sync));
+			DMEMIT(__raid_dev_status(rs, &rs->dev[i].rdev));
 
 		/*
 		 * In-sync/Reshape ratio:
@@ -3466,7 +3584,7 @@ static void raid_status(struct dm_target *ti, status_type_t type,
 		 * v1.10.0+:
 		 */
 		DMEMIT(" %s", test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags) ?
-			      __raid_dev_status(rs, &rs->journal_dev.rdev, 0) : "-");
+			      __raid_dev_status(rs, &rs->journal_dev.rdev) : "-");
 		break;
 
 	case STATUSTYPE_TABLE:
@@ -3622,24 +3740,19 @@ static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
 	blk_limits_io_opt(limits, chunk_size * mddev_data_stripes(rs));
 }
 
-static void raid_presuspend(struct dm_target *ti)
-{
-	struct raid_set *rs = ti->private;
-
-	md_stop_writes(&rs->md);
-}
-
 static void raid_postsuspend(struct dm_target *ti)
 {
 	struct raid_set *rs = ti->private;
 
 	if (!test_and_set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {
+		/* Writes have to be stopped before suspending to avoid deadlocks. */
+		if (!test_bit(MD_RECOVERY_FROZEN, &rs->md.recovery))
+			md_stop_writes(&rs->md);
+
 		mddev_lock_nointr(&rs->md);
 		mddev_suspend(&rs->md);
 		mddev_unlock(&rs->md);
 	}
-
-	rs->md.ro = 1;
 }
 
 static void attempt_restore_of_faulty_devices(struct raid_set *rs)
@@ -3816,10 +3929,33 @@ static int raid_preresume(struct dm_target *ti)
 	struct raid_set *rs = ti->private;
 	struct mddev *mddev = &rs->md;
 
-	/* This is a resume after a suspend of the set -> it's already started */
+	/* This is a resume after a suspend of the set -> it's already started. */
 	if (test_and_set_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags))
 		return 0;
 
+	if (!test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags)) {
+		struct raid_set *rs_active = rs_find_active(rs);
+
+		if (rs_active) {
+			/*
+			 * In case no rebuilds have been requested
+			 * and an active table slot exists, copy
+			 * current resynchonization completed and
+			 * reshape position pointers across from
+			 * suspended raid set in the active slot.
+			 *
+			 * This resumes the new mapping at current
+			 * offsets to continue recover/reshape without
+			 * necessarily redoing a raid set partially or
+			 * causing data corruption in case of a reshape.
+			 */
+			if (rs_active->md.curr_resync_completed != MaxSector)
+				mddev->curr_resync_completed = rs_active->md.curr_resync_completed;
+			if (rs_active->md.reshape_position != MaxSector)
+				mddev->reshape_position = rs_active->md.reshape_position;
+		}
+	}
+
 	/*
 	 * The superblocks need to be updated on disk if the
 	 * array is new or new devices got added (thus zeroed
@@ -3851,11 +3987,10 @@ static int raid_preresume(struct dm_target *ti)
 		mddev->resync_min = mddev->recovery_cp;
 	}
 
-	rs_set_capacity(rs);
-
 	/* Check for any reshape request unless new raid set */
-	if (test_and_clear_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
+	if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
 		/* Initiate a reshape. */
+		rs_set_rdev_sectors(rs);
 		mddev_lock_nointr(mddev);
 		r = rs_start_reshape(rs);
 		mddev_unlock(mddev);
@@ -3881,21 +4016,15 @@ static void raid_resume(struct dm_target *ti)
 		attempt_restore_of_faulty_devices(rs);
 	}
 
-	mddev->ro = 0;
-	mddev->in_sync = 0;
-
-	/*
-	 * Keep the RAID set frozen if reshape/rebuild flags are set.
-	 * The RAID set is unfrozen once the next table load/resume,
-	 * which clears the reshape/rebuild flags, occurs.
-	 * This ensures that the constructor for the inactive table
-	 * retrieves an up-to-date reshape_position.
-	 */
-	if (!(rs->ctr_flags & RESUME_STAY_FROZEN_FLAGS))
-		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
-
 	if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {
+		/* Only reduce raid set size before running a disk removing reshape. */
+		if (mddev->delta_disks < 0)
+			rs_set_capacity(rs);
+
 		mddev_lock_nointr(mddev);
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		mddev->ro = 0;
+		mddev->in_sync = 0;
 		mddev_resume(mddev);
 		mddev_unlock(mddev);
 	}
@@ -3903,7 +4032,7 @@ static void raid_resume(struct dm_target *ti)
 
 static struct target_type raid_target = {
 	.name = "raid",
-	.version = {1, 13, 0},
+	.version = {1, 13, 2},
 	.module = THIS_MODULE,
 	.ctr = raid_ctr,
 	.dtr = raid_dtr,
@@ -3912,7 +4041,6 @@ static struct target_type raid_target = {
 	.message = raid_message,
 	.iterate_devices = raid_iterate_devices,
 	.io_hints = raid_io_hints,
-	.presuspend = raid_presuspend,
 	.postsuspend = raid_postsuspend,
 	.preresume = raid_preresume,
 	.resume = raid_resume,

drivers/md/dm-rq.c

@@ -315,6 +315,10 @@ static void dm_done(struct request *clone, blk_status_t error, bool mapped)
 		/* The target wants to requeue the I/O */
 		dm_requeue_original_request(tio, false);
 		break;
+	case DM_ENDIO_DELAY_REQUEUE:
+		/* The target wants to requeue the I/O after a delay */
+		dm_requeue_original_request(tio, true);
+		break;
 	default:
 		DMWARN("unimplemented target endio return value: %d", r);
 		BUG();
@@ -713,7 +717,6 @@ int dm_old_init_request_queue(struct mapped_device *md, struct dm_table *t)
 	/* disable dm_old_request_fn's merge heuristic by default */
 	md->seq_rq_merge_deadline_usecs = 0;
 
-	dm_init_normal_md_queue(md);
 	blk_queue_softirq_done(md->queue, dm_softirq_done);
 
 	/* Initialize the request-based DM worker thread */
@@ -821,7 +824,6 @@ int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
 		err = PTR_ERR(q);
 		goto out_tag_set;
 	}
-	dm_init_md_queue(md);
 
 	return 0;
 

drivers/md/dm-service-time.c

@@ -282,9 +282,6 @@ static struct dm_path *st_select_path(struct path_selector *ps, size_t nr_bytes)
 	if (list_empty(&s->valid_paths))
 		goto out;
 
-	/* Change preferred (first in list) path to evenly balance. */
-	list_move_tail(s->valid_paths.next, &s->valid_paths);
-
 	list_for_each_entry(pi, &s->valid_paths, list)
 		if (!best || (st_compare_load(pi, best, nr_bytes) < 0))
 			best = pi;
@@ -292,6 +289,9 @@ static struct dm_path *st_select_path(struct path_selector *ps, size_t nr_bytes)
 	if (!best)
 		goto out;
 
+	/* Move most recently used to least preferred to evenly balance. */
+	list_move_tail(&best->list, &s->valid_paths);
+
 	ret = best->path;
 out:
 	spin_unlock_irqrestore(&s->lock, flags);

drivers/md/dm-snap.c

@@ -47,7 +47,7 @@ struct dm_exception_table {
 };
 
 struct dm_snapshot {
-	struct rw_semaphore lock;
+	struct mutex lock;
 
 	struct dm_dev *origin;
 	struct dm_dev *cow;
@@ -439,9 +439,9 @@ static int __find_snapshots_sharing_cow(struct dm_snapshot *snap,
 		if (!bdev_equal(s->cow->bdev, snap->cow->bdev))
 			continue;
 
-		down_read(&s->lock);
+		mutex_lock(&s->lock);
 		active = s->active;
-		up_read(&s->lock);
+		mutex_unlock(&s->lock);
 
 		if (active) {
 			if (snap_src)
@@ -909,7 +909,7 @@ static int remove_single_exception_chunk(struct dm_snapshot *s)
 	int r;
 	chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1;
 
-	down_write(&s->lock);
+	mutex_lock(&s->lock);
 
 	/*
 	 * Process chunks (and associated exceptions) in reverse order
@@ -924,7 +924,7 @@ static int remove_single_exception_chunk(struct dm_snapshot *s)
 	b = __release_queued_bios_after_merge(s);
 
 out:
-	up_write(&s->lock);
+	mutex_unlock(&s->lock);
 	if (b)
 		flush_bios(b);
 
@@ -983,9 +983,9 @@ static void snapshot_merge_next_chunks(struct dm_snapshot *s)
 		if (linear_chunks < 0) {
 			DMERR("Read error in exception store: "
 			      "shutting down merge");
-			down_write(&s->lock);
+			mutex_lock(&s->lock);
 			s->merge_failed = 1;
-			up_write(&s->lock);
+			mutex_unlock(&s->lock);
 		}
 		goto shut;
 	}
@@ -1026,10 +1026,10 @@ static void snapshot_merge_next_chunks(struct dm_snapshot *s)
 		previous_count = read_pending_exceptions_done_count();
 	}
 
-	down_write(&s->lock);
+	mutex_lock(&s->lock);
 	s->first_merging_chunk = old_chunk;
 	s->num_merging_chunks = linear_chunks;
-	up_write(&s->lock);
+	mutex_unlock(&s->lock);
 
 	/* Wait until writes to all 'linear_chunks' drain */
 	for (i = 0; i < linear_chunks; i++)
@@ -1071,10 +1071,10 @@ static void merge_callback(int read_err, unsigned long write_err, void *context)
 	return;
 
 shut:
-	down_write(&s->lock);
+	mutex_lock(&s->lock);
 	s->merge_failed = 1;
 	b = __release_queued_bios_after_merge(s);
-	up_write(&s->lock);
+	mutex_unlock(&s->lock);
 	error_bios(b);
 
 	merge_shutdown(s);
@@ -1173,7 +1173,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	s->exception_start_sequence = 0;
 	s->exception_complete_sequence = 0;
 	INIT_LIST_HEAD(&s->out_of_order_list);
-	init_rwsem(&s->lock);
+	mutex_init(&s->lock);
 	INIT_LIST_HEAD(&s->list);
 	spin_lock_init(&s->pe_lock);
 	s->state_bits = 0;
@@ -1338,9 +1338,9 @@ static void snapshot_dtr(struct dm_target *ti)
 	/* Check whether exception handover must be cancelled */
 	(void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL);
 	if (snap_src && snap_dest && (s == snap_src)) {
-		down_write(&snap_dest->lock);
+		mutex_lock(&snap_dest->lock);
 		snap_dest->valid = 0;
-		up_write(&snap_dest->lock);
+		mutex_unlock(&snap_dest->lock);
 		DMERR("Cancelling snapshot handover.");
 	}
 	up_read(&_origins_lock);
@@ -1371,6 +1371,8 @@ static void snapshot_dtr(struct dm_target *ti)
 
 	dm_exception_store_destroy(s->store);
 
+	mutex_destroy(&s->lock);
+
 	dm_put_device(ti, s->cow);
 
 	dm_put_device(ti, s->origin);
@@ -1458,7 +1460,7 @@ static void pending_complete(void *context, int success)
 
 	if (!success) {
 		/* Read/write error - snapshot is unusable */
-		down_write(&s->lock);
+		mutex_lock(&s->lock);
 		__invalidate_snapshot(s, -EIO);
 		error = 1;
 		goto out;
@@ -1466,14 +1468,14 @@ static void pending_complete(void *context, int success)
 
 	e = alloc_completed_exception(GFP_NOIO);
 	if (!e) {
-		down_write(&s->lock);
+		mutex_lock(&s->lock);
 		__invalidate_snapshot(s, -ENOMEM);
 		error = 1;
 		goto out;
 	}
 	*e = pe->e;
 
-	down_write(&s->lock);
+	mutex_lock(&s->lock);
 	if (!s->valid) {
 		free_completed_exception(e);
 		error = 1;
@@ -1498,7 +1500,7 @@ static void pending_complete(void *context, int success)
 		full_bio->bi_end_io = pe->full_bio_end_io;
 	increment_pending_exceptions_done_count();
 
-	up_write(&s->lock);
+	mutex_unlock(&s->lock);
 
 	/* Submit any pending write bios */
 	if (error) {
@@ -1694,7 +1696,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 
 	/* FIXME: should only take write lock if we need
 	 * to copy an exception */
-	down_write(&s->lock);
+	mutex_lock(&s->lock);
 
 	if (!s->valid || (unlikely(s->snapshot_overflowed) &&
 	    bio_data_dir(bio) == WRITE)) {
@@ -1717,9 +1719,9 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 	if (bio_data_dir(bio) == WRITE) {
 		pe = __lookup_pending_exception(s, chunk);
 		if (!pe) {
-			up_write(&s->lock);
+			mutex_unlock(&s->lock);
 			pe = alloc_pending_exception(s);
-			down_write(&s->lock);
+			mutex_lock(&s->lock);
 
 			if (!s->valid || s->snapshot_overflowed) {
 				free_pending_exception(pe);
@@ -1754,7 +1756,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 		    bio->bi_iter.bi_size ==
 		    (s->store->chunk_size << SECTOR_SHIFT)) {
 			pe->started = 1;
-			up_write(&s->lock);
+			mutex_unlock(&s->lock);
 			start_full_bio(pe, bio);
 			goto out;
 		}
@@ -1764,7 +1766,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 		if (!pe->started) {
 			/* this is protected by snap->lock */
 			pe->started = 1;
-			up_write(&s->lock);
+			mutex_unlock(&s->lock);
 			start_copy(pe);
 			goto out;
 		}
@@ -1774,7 +1776,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 	}
 
 out_unlock:
-	up_write(&s->lock);
+	mutex_unlock(&s->lock);
 out:
 	return r;
 }
@@ -1810,7 +1812,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio)
 
 	chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector);
 
-	down_write(&s->lock);
+	mutex_lock(&s->lock);
 
 	/* Full merging snapshots are redirected to the origin */
 	if (!s->valid)
@@ -1841,12 +1843,12 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio)
 	bio_set_dev(bio, s->origin->bdev);
 
 	if (bio_data_dir(bio) == WRITE) {
-		up_write(&s->lock);
+		mutex_unlock(&s->lock);
 		return do_origin(s->origin, bio);
 	}
 
 out_unlock:
-	up_write(&s->lock);
+	mutex_unlock(&s->lock);
 
 	return r;
 }
@@ -1878,7 +1880,7 @@ static int snapshot_preresume(struct dm_target *ti)
 	down_read(&_origins_lock);
 	(void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL);
 	if (snap_src && snap_dest) {
-		down_read(&snap_src->lock);
+		mutex_lock(&snap_src->lock);
 		if (s == snap_src) {
 			DMERR("Unable to resume snapshot source until "
 			      "handover completes.");
@@ -1888,7 +1890,7 @@ static int snapshot_preresume(struct dm_target *ti)
 			      "source is suspended.");
 			r = -EINVAL;
 		}
-		up_read(&snap_src->lock);
+		mutex_unlock(&snap_src->lock);
 	}
 	up_read(&_origins_lock);
 
@@ -1934,11 +1936,11 @@ static void snapshot_resume(struct dm_target *ti)
 
 	(void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL);
 	if (snap_src && snap_dest) {
-		down_write(&snap_src->lock);
-		down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING);
+		mutex_lock(&snap_src->lock);
+		mutex_lock_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING);
 		__handover_exceptions(snap_src, snap_dest);
-		up_write(&snap_dest->lock);
-		up_write(&snap_src->lock);
+		mutex_unlock(&snap_dest->lock);
+		mutex_unlock(&snap_src->lock);
 	}
 
 	up_read(&_origins_lock);
@@ -1953,9 +1955,9 @@ static void snapshot_resume(struct dm_target *ti)
 	/* Now we have correct chunk size, reregister */
 	reregister_snapshot(s);
 
-	down_write(&s->lock);
+	mutex_lock(&s->lock);
 	s->active = 1;
-	up_write(&s->lock);
+	mutex_unlock(&s->lock);
 }
 
 static uint32_t get_origin_minimum_chunksize(struct block_device *bdev)
@@ -1995,7 +1997,7 @@ static void snapshot_status(struct dm_target *ti, status_type_t type,
 	switch (type) {
 	case STATUSTYPE_INFO:
 
-		down_write(&snap->lock);
+		mutex_lock(&snap->lock);
 
 		if (!snap->valid)
 			DMEMIT("Invalid");
@@ -2020,7 +2022,7 @@ static void snapshot_status(struct dm_target *ti, status_type_t type,
 				DMEMIT("Unknown");
 		}
 
-		up_write(&snap->lock);
+		mutex_unlock(&snap->lock);
 
 		break;
 
@@ -2086,7 +2088,7 @@ static int __origin_write(struct list_head *snapshots, sector_t sector,
 		if (dm_target_is_snapshot_merge(snap->ti))
 			continue;
 
-		down_write(&snap->lock);
+		mutex_lock(&snap->lock);
 
 		/* Only deal with valid and active snapshots */
 		if (!snap->valid || !snap->active)
@@ -2113,9 +2115,9 @@ static int __origin_write(struct list_head *snapshots, sector_t sector,
 
 		pe = __lookup_pending_exception(snap, chunk);
 		if (!pe) {
-			up_write(&snap->lock);
+			mutex_unlock(&snap->lock);
 			pe = alloc_pending_exception(snap);
-			down_write(&snap->lock);
+			mutex_lock(&snap->lock);
 
 			if (!snap->valid) {
 				free_pending_exception(pe);
@@ -2158,7 +2160,7 @@ static int __origin_write(struct list_head *snapshots, sector_t sector,
 		}
 
 next_snapshot:
-		up_write(&snap->lock);
+		mutex_unlock(&snap->lock);
 
 		if (pe_to_start_now) {
 			start_copy(pe_to_start_now);

drivers/md/dm-stats.c

@@ -228,6 +228,7 @@ void dm_stats_cleanup(struct dm_stats *stats)
 		dm_stat_free(&s->rcu_head);
 	}
 	free_percpu(stats->last);
+	mutex_destroy(&stats->mutex);
 }
 
 static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end,

drivers/md/dm-table.c

@@ -866,7 +866,8 @@ EXPORT_SYMBOL(dm_consume_args);
 static bool __table_type_bio_based(enum dm_queue_mode table_type)
 {
 	return (table_type == DM_TYPE_BIO_BASED ||
-		table_type == DM_TYPE_DAX_BIO_BASED);
+		table_type == DM_TYPE_DAX_BIO_BASED ||
+		table_type == DM_TYPE_NVME_BIO_BASED);
 }
 
 static bool __table_type_request_based(enum dm_queue_mode table_type)
@@ -909,13 +910,33 @@ static bool dm_table_supports_dax(struct dm_table *t)
 	return true;
 }
 
+static bool dm_table_does_not_support_partial_completion(struct dm_table *t);
+
+struct verify_rq_based_data {
+	unsigned sq_count;
+	unsigned mq_count;
+};
+
+static int device_is_rq_based(struct dm_target *ti, struct dm_dev *dev,
+			      sector_t start, sector_t len, void *data)
+{
+	struct request_queue *q = bdev_get_queue(dev->bdev);
+	struct verify_rq_based_data *v = data;
+
+	if (q->mq_ops)
+		v->mq_count++;
+	else
+		v->sq_count++;
+
+	return queue_is_rq_based(q);
+}
+
 static int dm_table_determine_type(struct dm_table *t)
 {
 	unsigned i;
 	unsigned bio_based = 0, request_based = 0, hybrid = 0;
-	unsigned sq_count = 0, mq_count = 0;
+	struct verify_rq_based_data v = {.sq_count = 0, .mq_count = 0};
 	struct dm_target *tgt;
-	struct dm_dev_internal *dd;
 	struct list_head *devices = dm_table_get_devices(t);
 	enum dm_queue_mode live_md_type = dm_get_md_type(t->md);
 
@@ -923,6 +944,14 @@ static int dm_table_determine_type(struct dm_table *t)
 		/* target already set the table's type */
 		if (t->type == DM_TYPE_BIO_BASED)
 			return 0;
+		else if (t->type == DM_TYPE_NVME_BIO_BASED) {
+			if (!dm_table_does_not_support_partial_completion(t)) {
+				DMERR("nvme bio-based is only possible with devices"
+				      " that don't support partial completion");
+				return -EINVAL;
+			}
+			/* Fallthru, also verify all devices are blk-mq */
+		}
 		BUG_ON(t->type == DM_TYPE_DAX_BIO_BASED);
 		goto verify_rq_based;
 	}
@@ -937,7 +966,7 @@ static int dm_table_determine_type(struct dm_table *t)
 			bio_based = 1;
 
 		if (bio_based && request_based) {
-			DMWARN("Inconsistent table: different target types"
+			DMERR("Inconsistent table: different target types"
 			      " can't be mixed up");
 			return -EINVAL;
 		}
@@ -959,8 +988,18 @@ static int dm_table_determine_type(struct dm_table *t)
 		/* We must use this table as bio-based */
 		t->type = DM_TYPE_BIO_BASED;
 		if (dm_table_supports_dax(t) ||
-		    (list_empty(devices) && live_md_type == DM_TYPE_DAX_BIO_BASED))
+		    (list_empty(devices) && live_md_type == DM_TYPE_DAX_BIO_BASED)) {
 			t->type = DM_TYPE_DAX_BIO_BASED;
+		} else {
+			/* Check if upgrading to NVMe bio-based is valid or required */
+			tgt = dm_table_get_immutable_target(t);
+			if (tgt && !tgt->max_io_len && dm_table_does_not_support_partial_completion(t)) {
+				t->type = DM_TYPE_NVME_BIO_BASED;
+				goto verify_rq_based; /* must be stacked directly on NVMe (blk-mq) */
+			} else if (list_empty(devices) && live_md_type == DM_TYPE_NVME_BIO_BASED) {
+				t->type = DM_TYPE_NVME_BIO_BASED;
+			}
+		}
 		return 0;
 	}
 
@@ -980,7 +1019,8 @@ static int dm_table_determine_type(struct dm_table *t)
 	 * (e.g. request completion process for partial completion.)
 	 */
 	if (t->num_targets > 1) {
-		DMWARN("Request-based dm doesn't support multiple targets yet");
+		DMERR("%s DM doesn't support multiple targets",
+		      t->type == DM_TYPE_NVME_BIO_BASED ? "nvme bio-based" : "request-based");
 		return -EINVAL;
 	}
 
@@ -997,28 +1037,29 @@ static int dm_table_determine_type(struct dm_table *t)
 		return 0;
 	}
 
-	/* Non-request-stackable devices can't be used for request-based dm */
-	list_for_each_entry(dd, devices, list) {
-		struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
-
-		if (!queue_is_rq_based(q)) {
-			DMERR("table load rejected: including"
-			      " non-request-stackable devices");
+	tgt = dm_table_get_immutable_target(t);
+	if (!tgt) {
+		DMERR("table load rejected: immutable target is required");
+		return -EINVAL;
+	} else if (tgt->max_io_len) {
+		DMERR("table load rejected: immutable target that splits IO is not supported");
 		return -EINVAL;
 	}
 
-		if (q->mq_ops)
-			mq_count++;
-		else
-			sq_count++;
+	/* Non-request-stackable devices can't be used for request-based dm */
+	if (!tgt->type->iterate_devices ||
+	    !tgt->type->iterate_devices(tgt, device_is_rq_based, &v)) {
+		DMERR("table load rejected: including non-request-stackable devices");
+		return -EINVAL;
 	}
-	if (sq_count && mq_count) {
+	if (v.sq_count && v.mq_count) {
 		DMERR("table load rejected: not all devices are blk-mq request-stackable");
 		return -EINVAL;
 	}
-	t->all_blk_mq = mq_count > 0;
+	t->all_blk_mq = v.mq_count > 0;
 
-	if (t->type == DM_TYPE_MQ_REQUEST_BASED && !t->all_blk_mq) {
+	if (!t->all_blk_mq &&
+	    (t->type == DM_TYPE_MQ_REQUEST_BASED || t->type == DM_TYPE_NVME_BIO_BASED)) {
 		DMERR("table load rejected: all devices are not blk-mq request-stackable");
 		return -EINVAL;
 	}
@@ -1079,7 +1120,8 @@ static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *
 {
 	enum dm_queue_mode type = dm_table_get_type(t);
 	unsigned per_io_data_size = 0;
-	struct dm_target *tgt;
+	unsigned min_pool_size = 0;
+	struct dm_target *ti;
 	unsigned i;
 
 	if (unlikely(type == DM_TYPE_NONE)) {
@@ -1089,11 +1131,13 @@ static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *
 
 	if (__table_type_bio_based(type))
 		for (i = 0; i < t->num_targets; i++) {
-			tgt = t->targets + i;
-			per_io_data_size = max(per_io_data_size, tgt->per_io_data_size);
+			ti = t->targets + i;
+			per_io_data_size = max(per_io_data_size, ti->per_io_data_size);
+			min_pool_size = max(min_pool_size, ti->num_flush_bios);
 		}
 
-	t->mempools = dm_alloc_md_mempools(md, type, t->integrity_supported, per_io_data_size);
+	t->mempools = dm_alloc_md_mempools(md, type, t->integrity_supported,
+					   per_io_data_size, min_pool_size);
 	if (!t->mempools)
 		return -ENOMEM;
 
@@ -1705,6 +1749,20 @@ static bool dm_table_all_devices_attribute(struct dm_table *t,
 	return true;
 }
 
+static int device_no_partial_completion(struct dm_target *ti, struct dm_dev *dev,
+					sector_t start, sector_t len, void *data)
+{
+	char b[BDEVNAME_SIZE];
+
+	/* For now, NVMe devices are the only devices of this class */
+	return (strncmp(bdevname(dev->bdev, b), "nvme", 3) == 0);
+}
+
+static bool dm_table_does_not_support_partial_completion(struct dm_table *t)
+{
+	return dm_table_all_devices_attribute(t, device_no_partial_completion);
+}
+
 static int device_not_write_same_capable(struct dm_target *ti, struct dm_dev *dev,
 					 sector_t start, sector_t len, void *data)
 {
@@ -1820,6 +1878,8 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	}
 	blk_queue_write_cache(q, wc, fua);
 
+	if (dm_table_supports_dax(t))
+		queue_flag_set_unlocked(QUEUE_FLAG_DAX, q);
 	if (dm_table_supports_dax_write_cache(t))
 		dax_write_cache(t->md->dax_dev, true);
 

drivers/md/dm-thin.c

@@ -492,6 +492,11 @@ static void pool_table_init(void)
 	INIT_LIST_HEAD(&dm_thin_pool_table.pools);
 }
 
+static void pool_table_exit(void)
+{
+	mutex_destroy(&dm_thin_pool_table.mutex);
+}
+
 static void __pool_table_insert(struct pool *pool)
 {
 	BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
@@ -1717,7 +1722,7 @@ static void __remap_and_issue_shared_cell(void *context,
 		    bio_op(bio) == REQ_OP_DISCARD)
 			bio_list_add(&info->defer_bios, bio);
 		else {
-			struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));;
+			struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
 			h->shared_read_entry = dm_deferred_entry_inc(info->tc->pool->shared_read_ds);
 			inc_all_io_entry(info->tc->pool, bio);
@@ -4387,6 +4392,8 @@ static void dm_thin_exit(void)
 	dm_unregister_target(&pool_target);
 
 	kmem_cache_destroy(_new_mapping_cache);
+
+	pool_table_exit();
 }
 
 module_init(dm_thin_init);

drivers/md/dm-unstripe.c

+/*
+ * Copyright (C) 2017 Intel Corporation.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/device-mapper.h>
+
+struct unstripe_c {
+	struct dm_dev *dev;
+	sector_t physical_start;
+
+	uint32_t stripes;
+
+	uint32_t unstripe;
+	sector_t unstripe_width;
+	sector_t unstripe_offset;
+
+	uint32_t chunk_size;
+	u8 chunk_shift;
+};
+
+#define DM_MSG_PREFIX "unstriped"
+
+static void cleanup_unstripe(struct unstripe_c *uc, struct dm_target *ti)
+{
+	if (uc->dev)
+		dm_put_device(ti, uc->dev);
+	kfree(uc);
+}
+
+/*
+ * Contruct an unstriped mapping.
+ * <number of stripes> <chunk size> <stripe #> <dev_path> <offset>
+ */
+static int unstripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+	struct unstripe_c *uc;
+	sector_t tmp_len;
+	unsigned long long start;
+	char dummy;
+
+	if (argc != 5) {
+		ti->error = "Invalid number of arguments";
+		return -EINVAL;
+	}
+
+	uc = kzalloc(sizeof(*uc), GFP_KERNEL);
+	if (!uc) {
+		ti->error = "Memory allocation for unstriped context failed";
+		return -ENOMEM;
+	}
+
+	if (kstrtouint(argv[0], 10, &uc->stripes) || !uc->stripes) {
+		ti->error = "Invalid stripe count";
+		goto err;
+	}
+
+	if (kstrtouint(argv[1], 10, &uc->chunk_size) || !uc->chunk_size) {
+		ti->error = "Invalid chunk_size";
+		goto err;
+	}
+
+	// FIXME: must support non power of 2 chunk_size, dm-stripe.c does
+	if (!is_power_of_2(uc->chunk_size)) {
+		ti->error = "Non power of 2 chunk_size is not supported yet";
+		goto err;
+	}
+
+	if (kstrtouint(argv[2], 10, &uc->unstripe)) {
+		ti->error = "Invalid stripe number";
+		goto err;
+	}
+
+	if (uc->unstripe > uc->stripes && uc->stripes > 1) {
+		ti->error = "Please provide stripe between [0, # of stripes]";
+		goto err;
+	}
+
+	if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &uc->dev)) {
+		ti->error = "Couldn't get striped device";
+		goto err;
+	}
+
+	if (sscanf(argv[4], "%llu%c", &start, &dummy) != 1) {
+		ti->error = "Invalid striped device offset";
+		goto err;
+	}
+	uc->physical_start = start;
+
+	uc->unstripe_offset = uc->unstripe * uc->chunk_size;
+	uc->unstripe_width = (uc->stripes - 1) * uc->chunk_size;
+	uc->chunk_shift = fls(uc->chunk_size) - 1;
+
+	tmp_len = ti->len;
+	if (sector_div(tmp_len, uc->chunk_size)) {
+		ti->error = "Target length not divisible by chunk size";
+		goto err;
+	}
+
+	if (dm_set_target_max_io_len(ti, uc->chunk_size)) {
+		ti->error = "Failed to set max io len";
+		goto err;
+	}
+
+	ti->private = uc;
+	return 0;
+err:
+	cleanup_unstripe(uc, ti);
+	return -EINVAL;
+}
+
+static void unstripe_dtr(struct dm_target *ti)
+{
+	struct unstripe_c *uc = ti->private;
+
+	cleanup_unstripe(uc, ti);
+}
+
+static sector_t map_to_core(struct dm_target *ti, struct bio *bio)
+{
+	struct unstripe_c *uc = ti->private;
+	sector_t sector = bio->bi_iter.bi_sector;
+
+	/* Shift us up to the right "row" on the stripe */
+	sector += uc->unstripe_width * (sector >> uc->chunk_shift);
+
+	/* Account for what stripe we're operating on */
+	sector += uc->unstripe_offset;
+
+	return sector;
+}
+
+static int unstripe_map(struct dm_target *ti, struct bio *bio)
+{
+	struct unstripe_c *uc = ti->private;
+
+	bio_set_dev(bio, uc->dev->bdev);
+	bio->bi_iter.bi_sector = map_to_core(ti, bio) + uc->physical_start;
+
+	return DM_MAPIO_REMAPPED;
+}
+
+static void unstripe_status(struct dm_target *ti, status_type_t type,
+			    unsigned int status_flags, char *result, unsigned int maxlen)
+{
+	struct unstripe_c *uc = ti->private;
+	unsigned int sz = 0;
+
+	switch (type) {
+	case STATUSTYPE_INFO:
+		break;
+
+	case STATUSTYPE_TABLE:
+		DMEMIT("%d %llu %d %s %llu",
+		       uc->stripes, (unsigned long long)uc->chunk_size, uc->unstripe,
+		       uc->dev->name, (unsigned long long)uc->physical_start);
+		break;
+	}
+}
+
+static int unstripe_iterate_devices(struct dm_target *ti,
+				    iterate_devices_callout_fn fn, void *data)
+{
+	struct unstripe_c *uc = ti->private;
+
+	return fn(ti, uc->dev, uc->physical_start, ti->len, data);
+}
+
+static void unstripe_io_hints(struct dm_target *ti,
+			       struct queue_limits *limits)
+{
+	struct unstripe_c *uc = ti->private;
+
+	limits->chunk_sectors = uc->chunk_size;
+}
+
+static struct target_type unstripe_target = {
+	.name = "unstriped",
+	.version = {1, 0, 0},
+	.module = THIS_MODULE,
+	.ctr = unstripe_ctr,
+	.dtr = unstripe_dtr,
+	.map = unstripe_map,
+	.status = unstripe_status,
+	.iterate_devices = unstripe_iterate_devices,
+	.io_hints = unstripe_io_hints,
+};
+
+static int __init dm_unstripe_init(void)
+{
+	int r;
+
+	r = dm_register_target(&unstripe_target);
+	if (r < 0)
+		DMERR("target registration failed");
+
+	return r;
+}
+
+static void __exit dm_unstripe_exit(void)
+{
+	dm_unregister_target(&unstripe_target);
+}
+
+module_init(dm_unstripe_init);
+module_exit(dm_unstripe_exit);
+
+MODULE_DESCRIPTION(DM_NAME " unstriped target");
+MODULE_AUTHOR("Scott Bauer <scott.bauer@intel.com>");
+MODULE_LICENSE("GPL");

drivers/md/dm-zoned-metadata.c

@@ -2333,6 +2333,9 @@ static void dmz_cleanup_metadata(struct dmz_metadata *zmd)
 
 	/* Free the zone descriptors */
 	dmz_drop_zones(zmd);
+
+	mutex_destroy(&zmd->mblk_flush_lock);
+	mutex_destroy(&zmd->map_lock);
 }
 
 /*

drivers/md/dm-zoned-target.c

@@ -827,6 +827,7 @@ static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 err_cwq:
 	destroy_workqueue(dmz->chunk_wq);
 err_bio:
+	mutex_destroy(&dmz->chunk_lock);
 	bioset_free(dmz->bio_set);
 err_meta:
 	dmz_dtr_metadata(dmz->metadata);
@@ -861,6 +862,8 @@ static void dmz_dtr(struct dm_target *ti)
 
 	dmz_put_zoned_device(ti);
 
+	mutex_destroy(&dmz->chunk_lock);
+
 	kfree(dmz);
 }
 

drivers/md/dm.c

@@ -60,18 +60,73 @@ void dm_issue_global_event(void)
 }
 
 /*
- * One of these is allocated per bio.
+ * One of these is allocated (on-stack) per original bio.
  */
+struct clone_info {
+	struct dm_table *map;
+	struct bio *bio;
+	struct dm_io *io;
+	sector_t sector;
+	unsigned sector_count;
+};
+
+/*
+ * One of these is allocated per clone bio.
+ */
+#define DM_TIO_MAGIC 7282014
+struct dm_target_io {
+	unsigned magic;
+	struct dm_io *io;
+	struct dm_target *ti;
+	unsigned target_bio_nr;
+	unsigned *len_ptr;
+	bool inside_dm_io;
+	struct bio clone;
+};
+
+/*
+ * One of these is allocated per original bio.
+ * It contains the first clone used for that original.
+ */
+#define DM_IO_MAGIC 5191977
 struct dm_io {
+	unsigned magic;
 	struct mapped_device *md;
 	blk_status_t status;
 	atomic_t io_count;
-	struct bio *bio;
+	struct bio *orig_bio;
 	unsigned long start_time;
 	spinlock_t endio_lock;
 	struct dm_stats_aux stats_aux;
+	/* last member of dm_target_io is 'struct bio' */
+	struct dm_target_io tio;
 };
 
+void *dm_per_bio_data(struct bio *bio, size_t data_size)
+{
+	struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
+	if (!tio->inside_dm_io)
+		return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
+	return (char *)bio - offsetof(struct dm_target_io, clone) - offsetof(struct dm_io, tio) - data_size;
+}
+EXPORT_SYMBOL_GPL(dm_per_bio_data);
+
+struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
+{
+	struct dm_io *io = (struct dm_io *)((char *)data + data_size);
+	if (io->magic == DM_IO_MAGIC)
+		return (struct bio *)((char *)io + offsetof(struct dm_io, tio) + offsetof(struct dm_target_io, clone));
+	BUG_ON(io->magic != DM_TIO_MAGIC);
+	return (struct bio *)((char *)io + offsetof(struct dm_target_io, clone));
+}
+EXPORT_SYMBOL_GPL(dm_bio_from_per_bio_data);
+
+unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
+{
+	return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
+}
+EXPORT_SYMBOL_GPL(dm_bio_get_target_bio_nr);
+
 #define MINOR_ALLOCED ((void *)-1)
 
 /*
@@ -93,8 +148,8 @@ static int dm_numa_node = DM_NUMA_NODE;
  * For mempools pre-allocation at the table loading time.
  */
 struct dm_md_mempools {
-	mempool_t *io_pool;
 	struct bio_set *bs;
+	struct bio_set *io_bs;
 };
 
 struct table_device {
@@ -103,7 +158,6 @@ struct table_device {
 	struct dm_dev dm_dev;
 };
 
-static struct kmem_cache *_io_cache;
 static struct kmem_cache *_rq_tio_cache;
 static struct kmem_cache *_rq_cache;
 
@@ -170,14 +224,9 @@ static int __init local_init(void)
 {
 	int r = -ENOMEM;
 
-	/* allocate a slab for the dm_ios */
-	_io_cache = KMEM_CACHE(dm_io, 0);
-	if (!_io_cache)
-		return r;
-
 	_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
 	if (!_rq_tio_cache)
-		goto out_free_io_cache;
+		return r;
 
 	_rq_cache = kmem_cache_create("dm_old_clone_request", sizeof(struct request),
 				      __alignof__(struct request), 0, NULL);
@@ -212,8 +261,6 @@ static int __init local_init(void)
 	kmem_cache_destroy(_rq_cache);
 out_free_rq_tio_cache:
 	kmem_cache_destroy(_rq_tio_cache);
-out_free_io_cache:
-	kmem_cache_destroy(_io_cache);
 
 	return r;
 }
@@ -225,7 +272,6 @@ static void local_exit(void)
 
 	kmem_cache_destroy(_rq_cache);
 	kmem_cache_destroy(_rq_tio_cache);
-	kmem_cache_destroy(_io_cache);
 	unregister_blkdev(_major, _name);
 	dm_uevent_exit();
 
@@ -486,18 +532,69 @@ static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
 	return r;
 }
 
-static struct dm_io *alloc_io(struct mapped_device *md)
+static void start_io_acct(struct dm_io *io);
+
+static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
 {
-	return mempool_alloc(md->io_pool, GFP_NOIO);
+	struct dm_io *io;
+	struct dm_target_io *tio;
+	struct bio *clone;
+
+	clone = bio_alloc_bioset(GFP_NOIO, 0, md->io_bs);
+	if (!clone)
+		return NULL;
+
+	tio = container_of(clone, struct dm_target_io, clone);
+	tio->inside_dm_io = true;
+	tio->io = NULL;
+
+	io = container_of(tio, struct dm_io, tio);
+	io->magic = DM_IO_MAGIC;
+	io->status = 0;
+	atomic_set(&io->io_count, 1);
+	io->orig_bio = bio;
+	io->md = md;
+	spin_lock_init(&io->endio_lock);
+
+	start_io_acct(io);
+
+	return io;
 }
 
 static void free_io(struct mapped_device *md, struct dm_io *io)
 {
-	mempool_free(io, md->io_pool);
+	bio_put(&io->tio.clone);
+}
+
+static struct dm_target_io *alloc_tio(struct clone_info *ci, struct dm_target *ti,
+				      unsigned target_bio_nr, gfp_t gfp_mask)
+{
+	struct dm_target_io *tio;
+
+	if (!ci->io->tio.io) {
+		/* the dm_target_io embedded in ci->io is available */
+		tio = &ci->io->tio;
+	} else {
+		struct bio *clone = bio_alloc_bioset(gfp_mask, 0, ci->io->md->bs);
+		if (!clone)
+			return NULL;
+
+		tio = container_of(clone, struct dm_target_io, clone);
+		tio->inside_dm_io = false;
+	}
+
+	tio->magic = DM_TIO_MAGIC;
+	tio->io = ci->io;
+	tio->ti = ti;
+	tio->target_bio_nr = target_bio_nr;
+
+	return tio;
 }
 
 static void free_tio(struct dm_target_io *tio)
 {
+	if (tio->inside_dm_io)
+		return;
 	bio_put(&tio->clone);
 }
 
@@ -510,15 +607,13 @@ int md_in_flight(struct mapped_device *md)
 static void start_io_acct(struct dm_io *io)
 {
 	struct mapped_device *md = io->md;
-	struct bio *bio = io->bio;
-	int cpu;
+	struct bio *bio = io->orig_bio;
 	int rw = bio_data_dir(bio);
 
 	io->start_time = jiffies;
 
-	cpu = part_stat_lock();
-	part_round_stats(md->queue, cpu, &dm_disk(md)->part0);
-	part_stat_unlock();
+	generic_start_io_acct(md->queue, rw, bio_sectors(bio), &dm_disk(md)->part0);
+
 	atomic_set(&dm_disk(md)->part0.in_flight[rw],
 		   atomic_inc_return(&md->pending[rw]));
 
@@ -531,7 +626,7 @@ static void start_io_acct(struct dm_io *io)
 static void end_io_acct(struct dm_io *io)
 {
 	struct mapped_device *md = io->md;
-	struct bio *bio = io->bio;
+	struct bio *bio = io->orig_bio;
 	unsigned long duration = jiffies - io->start_time;
 	int pending;
 	int rw = bio_data_dir(bio);
@@ -752,15 +847,6 @@ int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
 	return 0;
 }
 
-/*-----------------------------------------------------------------
- * CRUD START:
- *   A more elegant soln is in the works that uses the queue
- *   merge fn, unfortunately there are a couple of changes to
- *   the block layer that I want to make for this.  So in the
- *   interests of getting something for people to use I give
- *   you this clearly demarcated crap.
- *---------------------------------------------------------------*/
-
 static int __noflush_suspending(struct mapped_device *md)
 {
 	return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
@@ -780,8 +866,7 @@ static void dec_pending(struct dm_io *io, blk_status_t error)
 	/* Push-back supersedes any I/O errors */
 	if (unlikely(error)) {
 		spin_lock_irqsave(&io->endio_lock, flags);
-		if (!(io->status == BLK_STS_DM_REQUEUE &&
-				__noflush_suspending(md)))
+		if (!(io->status == BLK_STS_DM_REQUEUE && __noflush_suspending(md)))
 			io->status = error;
 		spin_unlock_irqrestore(&io->endio_lock, flags);
 	}
@@ -793,7 +878,8 @@ static void dec_pending(struct dm_io *io, blk_status_t error)
 			 */
 			spin_lock_irqsave(&md->deferred_lock, flags);
 			if (__noflush_suspending(md))
-				bio_list_add_head(&md->deferred, io->bio);
+				/* NOTE early return due to BLK_STS_DM_REQUEUE below */
+				bio_list_add_head(&md->deferred, io->orig_bio);
 			else
 				/* noflush suspend was interrupted. */
 				io->status = BLK_STS_IOERR;
@@ -801,7 +887,7 @@ static void dec_pending(struct dm_io *io, blk_status_t error)
 		}
 
 		io_error = io->status;
-		bio = io->bio;
+		bio = io->orig_bio;
 		end_io_acct(io);
 		free_io(md, io);
 
@@ -847,7 +933,7 @@ static void clone_endio(struct bio *bio)
 	struct mapped_device *md = tio->io->md;
 	dm_endio_fn endio = tio->ti->type->end_io;
 
-	if (unlikely(error == BLK_STS_TARGET)) {
+	if (unlikely(error == BLK_STS_TARGET) && md->type != DM_TYPE_NVME_BIO_BASED) {
 		if (bio_op(bio) == REQ_OP_WRITE_SAME &&
 		    !bio->bi_disk->queue->limits.max_write_same_sectors)
 			disable_write_same(md);
@@ -1005,7 +1091,7 @@ static size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
 
 /*
  * A target may call dm_accept_partial_bio only from the map routine.  It is
- * allowed for all bio types except REQ_PREFLUSH.
+ * allowed for all bio types except REQ_PREFLUSH and REQ_OP_ZONE_RESET.
  *
  * dm_accept_partial_bio informs the dm that the target only wants to process
  * additional n_sectors sectors of the bio and the rest of the data should be
@@ -1055,7 +1141,7 @@ void dm_remap_zone_report(struct dm_target *ti, struct bio *bio, sector_t start)
 {
 #ifdef CONFIG_BLK_DEV_ZONED
 	struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
-	struct bio *report_bio = tio->io->bio;
+	struct bio *report_bio = tio->io->orig_bio;
 	struct blk_zone_report_hdr *hdr = NULL;
 	struct blk_zone *zone;
 	unsigned int nr_rep = 0;
@@ -1122,67 +1208,15 @@ void dm_remap_zone_report(struct dm_target *ti, struct bio *bio, sector_t start)
 }
 EXPORT_SYMBOL_GPL(dm_remap_zone_report);
 
-/*
- * Flush current->bio_list when the target map method blocks.
- * This fixes deadlocks in snapshot and possibly in other targets.
- */
-struct dm_offload {
-	struct blk_plug plug;
-	struct blk_plug_cb cb;
-};
-
-static void flush_current_bio_list(struct blk_plug_cb *cb, bool from_schedule)
-{
-	struct dm_offload *o = container_of(cb, struct dm_offload, cb);
-	struct bio_list list;
-	struct bio *bio;
-	int i;
-
-	INIT_LIST_HEAD(&o->cb.list);
-
-	if (unlikely(!current->bio_list))
-		return;
-
-	for (i = 0; i < 2; i++) {
-		list = current->bio_list[i];
-		bio_list_init(&current->bio_list[i]);
-
-		while ((bio = bio_list_pop(&list))) {
-			struct bio_set *bs = bio->bi_pool;
-			if (unlikely(!bs) || bs == fs_bio_set ||
-			    !bs->rescue_workqueue) {
-				bio_list_add(&current->bio_list[i], bio);
-				continue;
-			}
-
-			spin_lock(&bs->rescue_lock);
-			bio_list_add(&bs->rescue_list, bio);
-			queue_work(bs->rescue_workqueue, &bs->rescue_work);
-			spin_unlock(&bs->rescue_lock);
-		}
-	}
-}
-
-static void dm_offload_start(struct dm_offload *o)
-{
-	blk_start_plug(&o->plug);
-	o->cb.callback = flush_current_bio_list;
-	list_add(&o->cb.list, &current->plug->cb_list);
-}
-
-static void dm_offload_end(struct dm_offload *o)
-{
-	list_del(&o->cb.list);
-	blk_finish_plug(&o->plug);
-}
-
-static void __map_bio(struct dm_target_io *tio)
+static blk_qc_t __map_bio(struct dm_target_io *tio)
 {
 	int r;
 	sector_t sector;
-	struct dm_offload o;
 	struct bio *clone = &tio->clone;
+	struct dm_io *io = tio->io;
+	struct mapped_device *md = io->md;
 	struct dm_target *ti = tio->ti;
+	blk_qc_t ret = BLK_QC_T_NONE;
 
 	clone->bi_end_io = clone_endio;
 
@@ -1191,44 +1225,37 @@ static void __map_bio(struct dm_target_io *tio)
 	 * anything, the target has assumed ownership of
 	 * this io.
 	 */
-	atomic_inc(&tio->io->io_count);
+	atomic_inc(&io->io_count);
 	sector = clone->bi_iter.bi_sector;
 
-	dm_offload_start(&o);
 	r = ti->type->map(ti, clone);
-	dm_offload_end(&o);
-
 	switch (r) {
 	case DM_MAPIO_SUBMITTED:
 		break;
 	case DM_MAPIO_REMAPPED:
 		/* the bio has been remapped so dispatch it */
 		trace_block_bio_remap(clone->bi_disk->queue, clone,
-				      bio_dev(tio->io->bio), sector);
-		generic_make_request(clone);
+				      bio_dev(io->orig_bio), sector);
+		if (md->type == DM_TYPE_NVME_BIO_BASED)
+			ret = direct_make_request(clone);
+		else
+			ret = generic_make_request(clone);
 		break;
 	case DM_MAPIO_KILL:
-		dec_pending(tio->io, BLK_STS_IOERR);
 		free_tio(tio);
+		dec_pending(io, BLK_STS_IOERR);
 		break;
 	case DM_MAPIO_REQUEUE:
-		dec_pending(tio->io, BLK_STS_DM_REQUEUE);
 		free_tio(tio);
+		dec_pending(io, BLK_STS_DM_REQUEUE);
 		break;
 	default:
 		DMWARN("unimplemented target map return value: %d", r);
 		BUG();
 	}
-}
 
-struct clone_info {
-	struct mapped_device *md;
-	struct dm_table *map;
-	struct bio *bio;
-	struct dm_io *io;
-	sector_t sector;
-	unsigned sector_count;
-};
+	return ret;
+}
 
 static void bio_setup_sector(struct bio *bio, sector_t sector, unsigned len)
 {
@@ -1272,28 +1299,49 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio,
 	return 0;
 }
 
-static struct dm_target_io *alloc_tio(struct clone_info *ci,
-				      struct dm_target *ti,
-				      unsigned target_bio_nr)
+static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
+				struct dm_target *ti, unsigned num_bios)
 {
 	struct dm_target_io *tio;
-	struct bio *clone;
+	int try;
 
-	clone = bio_alloc_bioset(GFP_NOIO, 0, ci->md->bs);
-	tio = container_of(clone, struct dm_target_io, clone);
+	if (!num_bios)
+		return;
 
-	tio->io = ci->io;
-	tio->ti = ti;
-	tio->target_bio_nr = target_bio_nr;
+	if (num_bios == 1) {
+		tio = alloc_tio(ci, ti, 0, GFP_NOIO);
+		bio_list_add(blist, &tio->clone);
+		return;
+	}
 
-	return tio;
+	for (try = 0; try < 2; try++) {
+		int bio_nr;
+		struct bio *bio;
+
+		if (try)
+			mutex_lock(&ci->io->md->table_devices_lock);
+		for (bio_nr = 0; bio_nr < num_bios; bio_nr++) {
+			tio = alloc_tio(ci, ti, bio_nr, try ? GFP_NOIO : GFP_NOWAIT);
+			if (!tio)
+				break;
+
+			bio_list_add(blist, &tio->clone);
+		}
+		if (try)
+			mutex_unlock(&ci->io->md->table_devices_lock);
+		if (bio_nr == num_bios)
+			return;
+
+		while ((bio = bio_list_pop(blist))) {
+			tio = container_of(bio, struct dm_target_io, clone);
+			free_tio(tio);
+		}
+	}
 }
 
-static void __clone_and_map_simple_bio(struct clone_info *ci,
-				       struct dm_target *ti,
-				       unsigned target_bio_nr, unsigned *len)
+static blk_qc_t __clone_and_map_simple_bio(struct clone_info *ci,
+					   struct dm_target_io *tio, unsigned *len)
 {
-	struct dm_target_io *tio = alloc_tio(ci, ti, target_bio_nr);
 	struct bio *clone = &tio->clone;
 
 	tio->len_ptr = len;
@@ -1302,16 +1350,22 @@ static void __clone_and_map_simple_bio(struct clone_info *ci,
 	if (len)
 		bio_setup_sector(clone, ci->sector, *len);
 
-	__map_bio(tio);
+	return __map_bio(tio);
 }
 
 static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
 				  unsigned num_bios, unsigned *len)
 {
-	unsigned target_bio_nr;
+	struct bio_list blist = BIO_EMPTY_LIST;
+	struct bio *bio;
+	struct dm_target_io *tio;
+
+	alloc_multiple_bios(&blist, ci, ti, num_bios);
 
-	for (target_bio_nr = 0; target_bio_nr < num_bios; target_bio_nr++)
-		__clone_and_map_simple_bio(ci, ti, target_bio_nr, len);
+	while ((bio = bio_list_pop(&blist))) {
+		tio = container_of(bio, struct dm_target_io, clone);
+		(void) __clone_and_map_simple_bio(ci, tio, len);
+	}
 }
 
 static int __send_empty_flush(struct clone_info *ci)
@@ -1331,28 +1385,18 @@ static int __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
 {
 	struct bio *bio = ci->bio;
 	struct dm_target_io *tio;
-	unsigned target_bio_nr;
-	unsigned num_target_bios = 1;
-	int r = 0;
-
-	/*
-	 * Does the target want to receive duplicate copies of the bio?
-	 */
-	if (bio_data_dir(bio) == WRITE && ti->num_write_bios)
-		num_target_bios = ti->num_write_bios(ti, bio);
+	int r;
 
-	for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
-		tio = alloc_tio(ci, ti, target_bio_nr);
+	tio = alloc_tio(ci, ti, 0, GFP_NOIO);
 	tio->len_ptr = len;
 	r = clone_bio(tio, bio, sector, *len);
 	if (r < 0) {
 		free_tio(tio);
-			break;
-		}
-		__map_bio(tio);
+		return r;
 	}
+	(void) __map_bio(tio);
 
-	return r;
+	return 0;
 }
 
 typedef unsigned (*get_num_bios_fn)(struct dm_target *ti);
@@ -1379,19 +1423,13 @@ static bool is_split_required_for_discard(struct dm_target *ti)
 	return ti->split_discard_bios;
 }
 
-static int __send_changing_extent_only(struct clone_info *ci,
+static int __send_changing_extent_only(struct clone_info *ci, struct dm_target *ti,
 				       get_num_bios_fn get_num_bios,
 				       is_split_required_fn is_split_required)
 {
-	struct dm_target *ti;
 	unsigned len;
 	unsigned num_bios;
 
-	do {
-		ti = dm_table_find_target(ci->map, ci->sector);
-		if (!dm_target_is_valid(ti))
-			return -EIO;
-
 	/*
 	 * Even though the device advertised support for this type of
 	 * request, that does not mean every target supports it, and
@@ -1410,25 +1448,25 @@ static int __send_changing_extent_only(struct clone_info *ci,
 	__send_duplicate_bios(ci, ti, num_bios, &len);
 
 	ci->sector += len;
-	} while (ci->sector_count -= len);
+	ci->sector_count -= len;
 
 	return 0;
 }
 
-static int __send_discard(struct clone_info *ci)
+static int __send_discard(struct clone_info *ci, struct dm_target *ti)
 {
-	return __send_changing_extent_only(ci, get_num_discard_bios,
+	return __send_changing_extent_only(ci, ti, get_num_discard_bios,
 					   is_split_required_for_discard);
 }
 
-static int __send_write_same(struct clone_info *ci)
+static int __send_write_same(struct clone_info *ci, struct dm_target *ti)
 {
-	return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
+	return __send_changing_extent_only(ci, ti, get_num_write_same_bios, NULL);
 }
 
-static int __send_write_zeroes(struct clone_info *ci)
+static int __send_write_zeroes(struct clone_info *ci, struct dm_target *ti)
 {
-	return __send_changing_extent_only(ci, get_num_write_zeroes_bios, NULL);
+	return __send_changing_extent_only(ci, ti, get_num_write_zeroes_bios, NULL);
 }
 
 /*
@@ -1441,17 +1479,17 @@ static int __split_and_process_non_flush(struct clone_info *ci)
 	unsigned len;
 	int r;
 
-	if (unlikely(bio_op(bio) == REQ_OP_DISCARD))
-		return __send_discard(ci);
-	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
-		return __send_write_same(ci);
-	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES))
-		return __send_write_zeroes(ci);
-
 	ti = dm_table_find_target(ci->map, ci->sector);
 	if (!dm_target_is_valid(ti))
 		return -EIO;
 
+	if (unlikely(bio_op(bio) == REQ_OP_DISCARD))
+		return __send_discard(ci, ti);
+	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
+		return __send_write_same(ci, ti);
+	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES))
+		return __send_write_zeroes(ci, ti);
+
 	if (bio_op(bio) == REQ_OP_ZONE_REPORT)
 		len = ci->sector_count;
 	else
@@ -1468,34 +1506,33 @@ static int __split_and_process_non_flush(struct clone_info *ci)
 	return 0;
 }
 
+static void init_clone_info(struct clone_info *ci, struct mapped_device *md,
+			    struct dm_table *map, struct bio *bio)
+{
+	ci->map = map;
+	ci->io = alloc_io(md, bio);
+	ci->sector = bio->bi_iter.bi_sector;
+}
+
 /*
  * Entry point to split a bio into clones and submit them to the targets.
  */
-static void __split_and_process_bio(struct mapped_device *md,
+static blk_qc_t __split_and_process_bio(struct mapped_device *md,
 					struct dm_table *map, struct bio *bio)
 {
 	struct clone_info ci;
+	blk_qc_t ret = BLK_QC_T_NONE;
 	int error = 0;
 
 	if (unlikely(!map)) {
 		bio_io_error(bio);
-		return;
+		return ret;
 	}
 
-	ci.map = map;
-	ci.md = md;
-	ci.io = alloc_io(md);
-	ci.io->status = 0;
-	atomic_set(&ci.io->io_count, 1);
-	ci.io->bio = bio;
-	ci.io->md = md;
-	spin_lock_init(&ci.io->endio_lock);
-	ci.sector = bio->bi_iter.bi_sector;
-
-	start_io_acct(ci.io);
+	init_clone_info(&ci, md, map, bio);
 
 	if (bio->bi_opf & REQ_PREFLUSH) {
-		ci.bio = &ci.md->flush_bio;
+		ci.bio = &ci.io->md->flush_bio;
 		ci.sector_count = 0;
 		error = __send_empty_flush(&ci);
 		/* dec_pending submits any data associated with flush */
@@ -1506,32 +1543,95 @@ static void __split_and_process_bio(struct mapped_device *md,
 	} else {
 		ci.bio = bio;
 		ci.sector_count = bio_sectors(bio);
-		while (ci.sector_count && !error)
+		while (ci.sector_count && !error) {
 			error = __split_and_process_non_flush(&ci);
+			if (current->bio_list && ci.sector_count && !error) {
+				/*
+				 * Remainder must be passed to generic_make_request()
+				 * so that it gets handled *after* bios already submitted
+				 * have been completely processed.
+				 * We take a clone of the original to store in
+				 * ci.io->orig_bio to be used by end_io_acct() and
+				 * for dec_pending to use for completion handling.
+				 * As this path is not used for REQ_OP_ZONE_REPORT,
+				 * the usage of io->orig_bio in dm_remap_zone_report()
+				 * won't be affected by this reassignment.
+				 */
+				struct bio *b = bio_clone_bioset(bio, GFP_NOIO,
+								 md->queue->bio_split);
+				ci.io->orig_bio = b;
+				bio_advance(bio, (bio_sectors(bio) - ci.sector_count) << 9);
+				bio_chain(b, bio);
+				ret = generic_make_request(bio);
+				break;
+			}
+		}
 	}
 
 	/* drop the extra reference count */
 	dec_pending(ci.io, errno_to_blk_status(error));
+	return ret;
 }
-/*-----------------------------------------------------------------
- * CRUD END
- *---------------------------------------------------------------*/
 
 /*
- * The request function that just remaps the bio built up by
- * dm_merge_bvec.
+ * Optimized variant of __split_and_process_bio that leverages the
+ * fact that targets that use it do _not_ have a need to split bios.
  */
-static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t __process_bio(struct mapped_device *md,
+			      struct dm_table *map, struct bio *bio)
+{
+	struct clone_info ci;
+	blk_qc_t ret = BLK_QC_T_NONE;
+	int error = 0;
+
+	if (unlikely(!map)) {
+		bio_io_error(bio);
+		return ret;
+	}
+
+	init_clone_info(&ci, md, map, bio);
+
+	if (bio->bi_opf & REQ_PREFLUSH) {
+		ci.bio = &ci.io->md->flush_bio;
+		ci.sector_count = 0;
+		error = __send_empty_flush(&ci);
+		/* dec_pending submits any data associated with flush */
+	} else {
+		struct dm_target *ti = md->immutable_target;
+		struct dm_target_io *tio;
+
+		/*
+		 * Defend against IO still getting in during teardown
+		 * - as was seen for a time with nvme-fcloop
+		 */
+		if (unlikely(WARN_ON_ONCE(!ti || !dm_target_is_valid(ti)))) {
+			error = -EIO;
+			goto out;
+		}
+
+		tio = alloc_tio(&ci, ti, 0, GFP_NOIO);
+		ci.bio = bio;
+		ci.sector_count = bio_sectors(bio);
+		ret = __clone_and_map_simple_bio(&ci, tio, NULL);
+	}
+out:
+	/* drop the extra reference count */
+	dec_pending(ci.io, errno_to_blk_status(error));
+	return ret;
+}
+
+typedef blk_qc_t (process_bio_fn)(struct mapped_device *, struct dm_table *, struct bio *);
+
+static blk_qc_t __dm_make_request(struct request_queue *q, struct bio *bio,
+				  process_bio_fn process_bio)
 {
-	int rw = bio_data_dir(bio);
 	struct mapped_device *md = q->queuedata;
+	blk_qc_t ret = BLK_QC_T_NONE;
 	int srcu_idx;
 	struct dm_table *map;
 
 	map = dm_get_live_table(md, &srcu_idx);
 
-	generic_start_io_acct(q, rw, bio_sectors(bio), &dm_disk(md)->part0);
-
 	/* if we're suspended, we have to queue this io for later */
 	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
 		dm_put_live_table(md, srcu_idx);
@@ -1540,12 +1640,27 @@ static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
 			queue_io(md, bio);
 		else
 			bio_io_error(bio);
-		return BLK_QC_T_NONE;
+		return ret;
 	}
 
-	__split_and_process_bio(md, map, bio);
+	ret = process_bio(md, map, bio);
+
 	dm_put_live_table(md, srcu_idx);
-	return BLK_QC_T_NONE;
+	return ret;
+}
+
+/*
+ * The request function that remaps the bio to one target and
+ * splits off any remainder.
+ */
+static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
+{
+	return __dm_make_request(q, bio, __split_and_process_bio);
+}
+
+static blk_qc_t dm_make_request_nvme(struct request_queue *q, struct bio *bio)
+{
+	return __dm_make_request(q, bio, __process_bio);
 }
 
 static int dm_any_congested(void *congested_data, int bdi_bits)
@@ -1626,20 +1741,9 @@ static const struct dax_operations dm_dax_ops;
 
 static void dm_wq_work(struct work_struct *work);
 
-void dm_init_md_queue(struct mapped_device *md)
-{
-	/*
-	 * Initialize data that will only be used by a non-blk-mq DM queue
-	 * - must do so here (in alloc_dev callchain) before queue is used
-	 */
-	md->queue->queuedata = md;
-	md->queue->backing_dev_info->congested_data = md;
-}
-
-void dm_init_normal_md_queue(struct mapped_device *md)
+static void dm_init_normal_md_queue(struct mapped_device *md)
 {
 	md->use_blk_mq = false;
-	dm_init_md_queue(md);
 
 	/*
 	 * Initialize aspects of queue that aren't relevant for blk-mq
@@ -1653,9 +1757,10 @@ static void cleanup_mapped_device(struct mapped_device *md)
 		destroy_workqueue(md->wq);
 	if (md->kworker_task)
 		kthread_stop(md->kworker_task);
-	mempool_destroy(md->io_pool);
 	if (md->bs)
 		bioset_free(md->bs);
+	if (md->io_bs)
+		bioset_free(md->io_bs);
 
 	if (md->dax_dev) {
 		kill_dax(md->dax_dev);
@@ -1681,6 +1786,10 @@ static void cleanup_mapped_device(struct mapped_device *md)
 		md->bdev = NULL;
 	}
 
+	mutex_destroy(&md->suspend_lock);
+	mutex_destroy(&md->type_lock);
+	mutex_destroy(&md->table_devices_lock);
+
 	dm_mq_cleanup_mapped_device(md);
 }
 
@@ -1734,10 +1843,10 @@ static struct mapped_device *alloc_dev(int minor)
 	md->queue = blk_alloc_queue_node(GFP_KERNEL, numa_node_id);
 	if (!md->queue)
 		goto bad;
+	md->queue->queuedata = md;
+	md->queue->backing_dev_info->congested_data = md;
 
-	dm_init_md_queue(md);
-
-	md->disk = alloc_disk_node(1, numa_node_id);
+	md->disk = alloc_disk_node(1, md->numa_node_id);
 	if (!md->disk)
 		goto bad;
 
@@ -1820,17 +1929,22 @@ static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
 {
 	struct dm_md_mempools *p = dm_table_get_md_mempools(t);
 
-	if (md->bs) {
-		/* The md already has necessary mempools. */
 	if (dm_table_bio_based(t)) {
 		/*
-			 * Reload bioset because front_pad may have changed
+		 * The md may already have mempools that need changing.
+		 * If so, reload bioset because front_pad may have changed
 		 * because a different table was loaded.
 		 */
+		if (md->bs) {
 			bioset_free(md->bs);
-			md->bs = p->bs;
-			p->bs = NULL;
+			md->bs = NULL;
 		}
+		if (md->io_bs) {
+			bioset_free(md->io_bs);
+			md->io_bs = NULL;
+		}
+
+	} else if (md->bs) {
 		/*
 		 * There's no need to reload with request-based dm
 		 * because the size of front_pad doesn't change.
@@ -1842,13 +1956,12 @@ static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
 		goto out;
 	}
 
-	BUG_ON(!p || md->io_pool || md->bs);
+	BUG_ON(!p || md->bs || md->io_bs);
 
-	md->io_pool = p->io_pool;
-	p->io_pool = NULL;
 	md->bs = p->bs;
 	p->bs = NULL;
-
+	md->io_bs = p->io_bs;
+	p->io_bs = NULL;
 out:
 	/* mempool bind completed, no longer need any mempools in the table */
 	dm_table_free_md_mempools(t);
@@ -1894,6 +2007,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 {
 	struct dm_table *old_map;
 	struct request_queue *q = md->queue;
+	bool request_based = dm_table_request_based(t);
 	sector_t size;
 
 	lockdep_assert_held(&md->suspend_lock);
@@ -1917,12 +2031,15 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 	 * This must be done before setting the queue restrictions,
 	 * because request-based dm may be run just after the setting.
 	 */
-	if (dm_table_request_based(t)) {
+	if (request_based)
 		dm_stop_queue(q);
+
+	if (request_based || md->type == DM_TYPE_NVME_BIO_BASED) {
 		/*
-		 * Leverage the fact that request-based DM targets are
-		 * immutable singletons and establish md->immutable_target
-		 * - used to optimize both dm_request_fn and dm_mq_queue_rq
+		 * Leverage the fact that request-based DM targets and
+		 * NVMe bio based targets are immutable singletons
+		 * - used to optimize both dm_request_fn and dm_mq_queue_rq;
+		 *   and __process_bio.
 		 */
 		md->immutable_target = dm_table_get_immutable_target(t);
 	}
@@ -1962,13 +2079,18 @@ static struct dm_table *__unbind(struct mapped_device *md)
  */
 int dm_create(int minor, struct mapped_device **result)
 {
+	int r;
 	struct mapped_device *md;
 
 	md = alloc_dev(minor);
 	if (!md)
 		return -ENXIO;
 
-	dm_sysfs_init(md);
+	r = dm_sysfs_init(md);
+	if (r) {
+		free_dev(md);
+		return r;
+	}
 
 	*result = md;
 	return 0;
@@ -2026,6 +2148,7 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
 
 	switch (type) {
 	case DM_TYPE_REQUEST_BASED:
+		dm_init_normal_md_queue(md);
 		r = dm_old_init_request_queue(md, t);
 		if (r) {
 			DMERR("Cannot initialize queue for request-based mapped device");
@@ -2043,15 +2166,10 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
 	case DM_TYPE_DAX_BIO_BASED:
 		dm_init_normal_md_queue(md);
 		blk_queue_make_request(md->queue, dm_make_request);
-		/*
-		 * DM handles splitting bios as needed.  Free the bio_split bioset
-		 * since it won't be used (saves 1 process per bio-based DM device).
-		 */
-		bioset_free(md->queue->bio_split);
-		md->queue->bio_split = NULL;
-
-		if (type == DM_TYPE_DAX_BIO_BASED)
-			queue_flag_set_unlocked(QUEUE_FLAG_DAX, md->queue);
+		break;
+	case DM_TYPE_NVME_BIO_BASED:
+		dm_init_normal_md_queue(md);
+		blk_queue_make_request(md->queue, dm_make_request_nvme);
 		break;
 	case DM_TYPE_NONE:
 		WARN_ON_ONCE(true);
@@ -2130,7 +2248,6 @@ EXPORT_SYMBOL_GPL(dm_device_name);
 
 static void __dm_destroy(struct mapped_device *md, bool wait)
 {
-	struct request_queue *q = dm_get_md_queue(md);
 	struct dm_table *map;
 	int srcu_idx;
 
@@ -2141,7 +2258,7 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
 	set_bit(DMF_FREEING, &md->flags);
 	spin_unlock(&_minor_lock);
 
-	blk_set_queue_dying(q);
+	blk_set_queue_dying(md->queue);
 
 	if (dm_request_based(md) && md->kworker_task)
 		kthread_flush_worker(&md->kworker);
@@ -2752,11 +2869,12 @@ int dm_noflush_suspending(struct dm_target *ti)
 EXPORT_SYMBOL_GPL(dm_noflush_suspending);
 
 struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, enum dm_queue_mode type,
-					    unsigned integrity, unsigned per_io_data_size)
+					    unsigned integrity, unsigned per_io_data_size,
+					    unsigned min_pool_size)
 {
 	struct dm_md_mempools *pools = kzalloc_node(sizeof(*pools), GFP_KERNEL, md->numa_node_id);
 	unsigned int pool_size = 0;
-	unsigned int front_pad;
+	unsigned int front_pad, io_front_pad;
 
 	if (!pools)
 		return NULL;
@@ -2764,16 +2882,19 @@ struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, enum dm_qu
 	switch (type) {
 	case DM_TYPE_BIO_BASED:
 	case DM_TYPE_DAX_BIO_BASED:
-		pool_size = dm_get_reserved_bio_based_ios();
+	case DM_TYPE_NVME_BIO_BASED:
+		pool_size = max(dm_get_reserved_bio_based_ios(), min_pool_size);
 		front_pad = roundup(per_io_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
-	
-		pools->io_pool = mempool_create_slab_pool(pool_size, _io_cache);
-		if (!pools->io_pool)
+		io_front_pad = roundup(front_pad,  __alignof__(struct dm_io)) + offsetof(struct dm_io, tio);
+		pools->io_bs = bioset_create(pool_size, io_front_pad, 0);
+		if (!pools->io_bs)
+			goto out;
+		if (integrity && bioset_integrity_create(pools->io_bs, pool_size))
 			goto out;
 		break;
 	case DM_TYPE_REQUEST_BASED:
 	case DM_TYPE_MQ_REQUEST_BASED:
-		pool_size = dm_get_reserved_rq_based_ios();
+		pool_size = max(dm_get_reserved_rq_based_ios(), min_pool_size);
 		front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
 		/* per_io_data_size is used for blk-mq pdu at queue allocation */
 		break;
@@ -2781,7 +2902,7 @@ struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, enum dm_qu
 		BUG();
 	}
 
-	pools->bs = bioset_create(pool_size, front_pad, BIOSET_NEED_RESCUER);
+	pools->bs = bioset_create(pool_size, front_pad, 0);
 	if (!pools->bs)
 		goto out;
 
@@ -2801,10 +2922,10 @@ void dm_free_md_mempools(struct dm_md_mempools *pools)
 	if (!pools)
 		return;
 
-	mempool_destroy(pools->io_pool);
-
 	if (pools->bs)
 		bioset_free(pools->bs);
+	if (pools->io_bs)
+		bioset_free(pools->io_bs);
 
 	kfree(pools);
 }

drivers/md/dm.h

@@ -49,7 +49,6 @@ struct dm_md_mempools;
 /*-----------------------------------------------------------------
  * Internal table functions.
  *---------------------------------------------------------------*/
-void dm_table_destroy(struct dm_table *t);
 void dm_table_event_callback(struct dm_table *t,
 			     void (*fn)(void *), void *context);
 struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index);
@@ -206,7 +205,8 @@ void dm_kcopyd_exit(void);
  * Mempool operations
  */
 struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, enum dm_queue_mode type,
-					    unsigned integrity, unsigned per_bio_data_size);
+					    unsigned integrity, unsigned per_bio_data_size,
+					    unsigned min_pool_size);
 void dm_free_md_mempools(struct dm_md_mempools *pools);
 
 /*

include/linux/device-mapper.h

@@ -28,6 +28,7 @@ enum dm_queue_mode {
 	DM_TYPE_REQUEST_BASED	 = 2,
 	DM_TYPE_MQ_REQUEST_BASED = 3,
 	DM_TYPE_DAX_BIO_BASED	 = 4,
+	DM_TYPE_NVME_BIO_BASED	 = 5,
 };
 
 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
@@ -220,14 +221,6 @@ struct target_type {
 #define DM_TARGET_WILDCARD		0x00000008
 #define dm_target_is_wildcard(type)	((type)->features & DM_TARGET_WILDCARD)
 
-/*
- * Some targets need to be sent the same WRITE bio severals times so
- * that they can send copies of it to different devices.  This function
- * examines any supplied bio and returns the number of copies of it the
- * target requires.
- */
-typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
-
 /*
  * A target implements own bio data integrity.
  */
@@ -291,13 +284,6 @@ struct dm_target {
 	 */
 	unsigned per_io_data_size;
 
-	/*
-	 * If defined, this function is called to find out how many
-	 * duplicate bios should be sent to the target when writing
-	 * data.
-	 */
-	dm_num_write_bios_fn num_write_bios;
-
 	/* target specific data */
 	void *private;
 
@@ -329,35 +315,9 @@ struct dm_target_callbacks {
 	int (*congested_fn) (struct dm_target_callbacks *, int);
 };
 
-/*
- * For bio-based dm.
- * One of these is allocated for each bio.
- * This structure shouldn't be touched directly by target drivers.
- * It is here so that we can inline dm_per_bio_data and
- * dm_bio_from_per_bio_data
- */
-struct dm_target_io {
-	struct dm_io *io;
-	struct dm_target *ti;
-	unsigned target_bio_nr;
-	unsigned *len_ptr;
-	struct bio clone;
-};
-
-static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
-{
-	return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
-}
-
-static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
-{
-	return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
-}
-
-static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
-{
-	return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
-}
+void *dm_per_bio_data(struct bio *bio, size_t data_size);
+struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size);
+unsigned dm_bio_get_target_bio_nr(const struct bio *bio);
 
 int dm_register_target(struct target_type *t);
 void dm_unregister_target(struct target_type *t);
@@ -499,6 +459,11 @@ void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type);
  */
 int dm_table_complete(struct dm_table *t);
 
+/*
+ * Destroy the table when finished.
+ */
+void dm_table_destroy(struct dm_table *t);
+
 /*
  * Target may require that it is never sent I/O larger than len.
  */
@@ -585,6 +550,7 @@ do {									\
 #define DM_ENDIO_DONE		0
 #define DM_ENDIO_INCOMPLETE	1
 #define DM_ENDIO_REQUEUE	2
+#define DM_ENDIO_DELAY_REQUEUE	3
 
 /*
  * Definitions of return values from target map function.
@@ -592,7 +558,7 @@ do {									\
 #define DM_MAPIO_SUBMITTED	0
 #define DM_MAPIO_REMAPPED	1
 #define DM_MAPIO_REQUEUE	DM_ENDIO_REQUEUE
-#define DM_MAPIO_DELAY_REQUEUE	3
+#define DM_MAPIO_DELAY_REQUEUE	DM_ENDIO_DELAY_REQUEUE
 #define DM_MAPIO_KILL		4
 
 #define dm_sector_div64(x, y)( \