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) {
-		pgpath->is_active = true;
-		INIT_DELAYED_WORK(&pgpath->activate_path, activate_path_work);
-	}
+	if (!pgpath)
+		return NULL;
+
+	pgpath->is_active = true;
 
 	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;
@@ -221,13 +210,26 @@ 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);
-		/*
-		 * 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_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);
+	struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
 
-	memset(mpio, 0, sizeof(*mpio));
-	memset(bio_details, 0, sizeof(*bio_details));
-	dm_bio_record(bio_details, bio);
+	mpio->nr_bytes = bio->bi_iter.bi_size;
+	mpio->pgpath = NULL;
+	*mpio_p = mpio;
 
-	if (mpio_p)
-		*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);
@@ -385,7 +385,8 @@ static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
 	unsigned bypassed = 1;
 
 	if (!atomic_read(&m->nr_valid_paths)) {
-		clear_bit(MPATHF_QUEUE_IO, &m->flags);
+		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))
-			return DM_MAPIO_DELAY_REQUEUE;
-		return DM_MAPIO_REQUEUE;
+		pg_init_all_paths(m);
+		return DM_MAPIO_DELAY_REQUEUE;
 	}
 
-	memset(mpio, 0, sizeof(*mpio));
 	mpio->pgpath = pgpath;
 	mpio->nr_bytes = nr_bytes;
 
@@ -530,12 +529,23 @@ 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;
 		}
-		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;
 	clone->rq_disk = bdev->bd_disk;
@@ -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:
@@ -811,26 +847,59 @@ 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);
-				goto bad;
+				*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;
+		}
+	}
+
 	r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
 	if (r) {
 		dm_put_device(ti, p->path.dev);
@@ -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)
 {
-	set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
-	smp_mb__after_atomic();
+	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);
+
+		clear_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();
 }
 
 static void multipath_dtr(struct dm_target *ti)
@@ -1496,7 +1570,10 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
 	if (error && blk_path_error(error)) {
 		struct multipath *m = ti->private;
 
-		r = DM_ENDIO_REQUEUE;
+		if (error == BLK_STS_RESOURCE)
+			r = DM_ENDIO_DELAY_REQUEUE;
+		else
+			r = DM_ENDIO_REQUEUE;
 
 		if (pgpath)
 			fail_path(pgpath);
@@ -1521,7 +1598,7 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
 }
 
 static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
-		blk_status_t *error)
+				blk_status_t *error)
 {
 	struct multipath *m = ti->private;
 	struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
@@ -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-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;
 	}
@@ -937,8 +966,8 @@ static int dm_table_determine_type(struct dm_table *t)
 			bio_based = 1;
 
 		if (bio_based && request_based) {
-			DMWARN("Inconsistent table: different target types"
-			       " can't be mixed up");
+			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");
-			return -EINVAL;
-		}
+	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.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)( \