Merge tag 'dm-4.8-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

- initially based on Jens' 'for-4.8/core' (given all the flag churn)
and later merged with 'for-4.8/core' to pickup the QUEUE_FLAG_DAX
commits that DM depends on to provide its DAX support

- clean up the bio-based vs request-based DM core code by moving the
request-based DM core code out to dm-rq.[hc]

- reinstate bio-based support in the DM multipath target (done with the
idea that fast storage like NVMe over Fabrics could benefit) -- while
preserving support for request_fn and blk-mq request-based DM mpath

- SCSI and DM multipath persistent reservation fixes that were
coordinated with Martin Petersen.

- the DM raid target saw the most extensive change this cycle; it now
provides reshape and takeover support (by layering ontop of the
corresponding MD capabilities)

- DAX support for DM core and the linear, stripe and error targets

- a DM thin-provisioning block discard vs allocation race fix that
addresses potential for corruption

- a stable fix for DM verity-fec's block calculation during decode

- a few cleanups and fixes to DM core and various targets

* tag 'dm-4.8-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (73 commits)
dm: allow bio-based table to be upgraded to bio-based with DAX support
dm snap: add fake origin_direct_access
dm stripe: add DAX support
dm error: add DAX support
dm linear: add DAX support
dm: add infrastructure for DAX support
dm thin: fix a race condition between discarding and provisioning a block
dm btree: fix a bug in dm_btree_find_next_single()
dm raid: fix random optimal_io_size for raid0
dm raid: address checkpatch.pl complaints
dm: call PR reserve/unreserve on each underlying device
sd: don't use the ALL_TG_PT bit for reservations
dm: fix second blk_delay_queue() parameter to be in msec units not jiffies
dm raid: change logical functions to actually return bool
dm raid: use rdev_for_each in status
dm raid: use rs->raid_disks to avoid memory leaks on free
dm raid: support delta_disks for raid1, fix table output
dm raid: enhance reshape check and factor out reshape setup
dm raid: allow resize during recovery
dm raid: fix rs_is_recovering() to allow for lvextend
...

Documentation/device-mapper/dm-raid.txt

···
     <#raid_devs> <metadata_dev0> <dev0> [.. <metadata_devN> <devN>]
 
 <raid_type>:
+  raid0		RAID0 striping (no resilience)
   raid1		RAID1 mirroring
-  raid4		RAID4 dedicated parity disk
+  raid4		RAID4 with dedicated last parity disk
+  raid5_n 	RAID5 with dedicated last parity disk suporting takeover
+		Same as raid4
+		-Transitory layout
   raid5_la	RAID5 left asymmetric
 		- rotating parity 0 with data continuation
   raid5_ra	RAID5 right asymmetric
···
 		- rotating parity N (right-to-left) with data restart
   raid6_nc	RAID6 N continue
 		- rotating parity N (right-to-left) with data continuation
+  raid6_n_6	RAID6 with dedicate parity disks
+		- parity and Q-syndrome on the last 2 disks;
+		  laylout for takeover from/to raid4/raid5_n
+  raid6_la_6	Same as "raid_la" plus dedicated last Q-syndrome disk
+		- layout for takeover from raid5_la from/to raid6
+  raid6_ra_6	Same as "raid5_ra" dedicated last Q-syndrome disk
+		- layout for takeover from raid5_ra from/to raid6
+  raid6_ls_6	Same as "raid5_ls" dedicated last Q-syndrome disk
+		- layout for takeover from raid5_ls from/to raid6
+  raid6_rs_6	Same as "raid5_rs" dedicated last Q-syndrome disk
+		- layout for takeover from raid5_rs from/to raid6
   raid10        Various RAID10 inspired algorithms chosen by additional params
+		(see raid10_format and raid10_copies below)
 		- RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
 		- RAID1E: Integrated Adjacent Stripe Mirroring
 		- RAID1E: Integrated Offset Stripe Mirroring
···
 		Here we see layouts closely akin to 'RAID1E - Integrated
 		Offset Stripe Mirroring'.
 
+        [delta_disks <N>]
+		The delta_disks option value (-251 < N < +251) triggers
+		device removal (negative value) or device addition (positive
+		value) to any reshape supporting raid levels 4/5/6 and 10.
+		RAID levels 4/5/6 allow for addition of devices (metadata
+		and data device tupel), raid10_near and raid10_offset only
+		allow for device addtion. raid10_far does not support any
+		reshaping at all.
+		A minimum of devices have to be kept to enforce resilience,
+		which is 3 devices for raid4/5 and 4 devices for raid6.
+
+        [data_offset <sectors>]
+		This option value defines the offset into each data device
+		where the data starts. This is used to provide out-of-place
+		reshaping space to avoid writing over data whilst
+		changing the layout of stripes, hence an interruption/crash
+		may happen at any time without the risk of losing data.
+		E.g. when adding devices to an existing raid set during
+		forward reshaping, the out-of-place space will be allocated
+		at the beginning of each raid device. The kernel raid4/5/6/10
+		MD personalities supporting such device addition will read the data from
+		the existing first stripes (those with smaller number of stripes)
+		starting at data_offset to fill up a new stripe with the larger
+		number of stripes, calculate the redundancy blocks (CRC/Q-syndrome)
+		and write that new stripe to offset 0. Same will be applied to all
+		N-1 other new stripes. This out-of-place scheme is used to change
+		the RAID type (i.e. the allocation algorithm) as well, e.g.
+		changing from raid5_ls to raid5_n.
+
 <#raid_devs>: The number of devices composing the array.
 	Each device consists of two entries.  The first is the device
 	containing the metadata (if any); the second is the one containing the
-	data.
+	data. A Maximum of 64 metadata/data device entries are supported
+	up to target version 1.8.0.
+	1.9.0 supports up to 253 which is enforced by the used MD kernel runtime.
 
 	If a drive has failed or is missing at creation time, a '-' can be
 	given for both the metadata and data drives for a given position.
···
 	"recover"- Initiate/continue a recover process.
 	"check"  - Initiate a check (i.e. a "scrub") of the array.
 	"repair" - Initiate a repair of the array.
-	"reshape"- Currently unsupported (-EINVAL).
 
 
 Discard Support
···
 1.5.2   'mismatch_cnt' is zero unless [last_]sync_action is "check".
 1.6.0   Add discard support (and devices_handle_discard_safely module param).
 1.7.0   Add support for MD RAID0 mappings.
+1.8.0   Explictely check for compatible flags in the superblock metadata
+	and reject to start the raid set if any are set by a newer
+	target version, thus avoiding data corruption on a raid set
+	with a reshape in progress.
+1.9.0   Add support for RAID level takeover/reshape/region size
+	and set size reduction.

drivers/md/Makefile

···
 #
 
 dm-mod-y	+= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
-		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o
+		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o \
+		   dm-rq.o
 dm-multipath-y	+= dm-path-selector.o dm-mpath.o
 dm-snapshot-y	+= dm-snap.o dm-exception-store.o dm-snap-transient.o \
 		    dm-snap-persistent.o

drivers/md/dm-builtin.c

···
-#include "dm.h"
+#include "dm-core.h"
 
 /*
  * The kobject release method must not be placed in the module itself,

drivers/md/dm-core.h

···
+/*
+ * Internal header file _only_ for device mapper core
+ *
+ * Copyright (C) 2016 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the LGPL.
+ */
+
+#ifndef DM_CORE_INTERNAL_H
+#define DM_CORE_INTERNAL_H
+
+#include <linux/kthread.h>
+#include <linux/ktime.h>
+#include <linux/blk-mq.h>
+
+#include <trace/events/block.h>
+
+#include "dm.h"
+
+#define DM_RESERVED_MAX_IOS		1024
+
+struct dm_kobject_holder {
+	struct kobject kobj;
+	struct completion completion;
+};
+
+/*
+ * DM core internal structure that used directly by dm.c and dm-rq.c
+ * DM targets must _not_ deference a mapped_device to directly access its members!
+ */
+struct mapped_device {
+	struct srcu_struct io_barrier;
+	struct mutex suspend_lock;
+
+	/*
+	 * The current mapping (struct dm_table *).
+	 * Use dm_get_live_table{_fast} or take suspend_lock for
+	 * dereference.
+	 */
+	void __rcu *map;
+
+	struct list_head table_devices;
+	struct mutex table_devices_lock;
+
+	unsigned long flags;
+
+	struct request_queue *queue;
+	int numa_node_id;
+
+	unsigned type;
+	/* Protect queue and type against concurrent access. */
+	struct mutex type_lock;
+
+	atomic_t holders;
+	atomic_t open_count;
+
+	struct dm_target *immutable_target;
+	struct target_type *immutable_target_type;
+
+	struct gendisk *disk;
+	char name[16];
+
+	void *interface_ptr;
+
+	/*
+	 * A list of ios that arrived while we were suspended.
+	 */
+	atomic_t pending[2];
+	wait_queue_head_t wait;
+	struct work_struct work;
+	spinlock_t deferred_lock;
+	struct bio_list deferred;
+
+	/*
+	 * Event handling.
+	 */
+	wait_queue_head_t eventq;
+	atomic_t event_nr;
+	atomic_t uevent_seq;
+	struct list_head uevent_list;
+	spinlock_t uevent_lock; /* Protect access to uevent_list */
+
+	/* the number of internal suspends */
+	unsigned internal_suspend_count;
+
+	/*
+	 * Processing queue (flush)
+	 */
+	struct workqueue_struct *wq;
+
+	/*
+	 * io objects are allocated from here.
+	 */
+	mempool_t *io_pool;
+	mempool_t *rq_pool;
+
+	struct bio_set *bs;
+
+	/*
+	 * freeze/thaw support require holding onto a super block
+	 */
+	struct super_block *frozen_sb;
+
+	/* forced geometry settings */
+	struct hd_geometry geometry;
+
+	struct block_device *bdev;
+
+	/* kobject and completion */
+	struct dm_kobject_holder kobj_holder;
+
+	/* zero-length flush that will be cloned and submitted to targets */
+	struct bio flush_bio;
+
+	struct dm_stats stats;
+
+	struct kthread_worker kworker;
+	struct task_struct *kworker_task;
+
+	/* for request-based merge heuristic in dm_request_fn() */
+	unsigned seq_rq_merge_deadline_usecs;
+	int last_rq_rw;
+	sector_t last_rq_pos;
+	ktime_t last_rq_start_time;
+
+	/* for blk-mq request-based DM support */
+	struct blk_mq_tag_set *tag_set;
+	bool use_blk_mq:1;
+	bool init_tio_pdu:1;
+};
+
+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);
+
+static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
+{
+	return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;
+}
+
+unsigned __dm_get_module_param(unsigned *module_param, unsigned def, unsigned max);
+
+static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen)
+{
+	return !maxlen || strlen(result) + 1 >= maxlen;
+}
+
+#endif

drivers/md/dm-crypt.c

···
 				  u8 *data)
 {
 	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
-	u64 sector = cpu_to_le64((u64)dmreq->iv_sector);
+	__le64 sector = cpu_to_le64(dmreq->iv_sector);
 	u8 buf[TCW_WHITENING_SIZE];
 	SHASH_DESC_ON_STACK(desc, tcw->crc32_tfm);
 	int i, r;
···
 			    struct dm_crypt_request *dmreq)
 {
 	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
-	u64 sector = cpu_to_le64((u64)dmreq->iv_sector);
+	__le64 sector = cpu_to_le64(dmreq->iv_sector);
 	u8 *src;
 	int r = 0;
 

drivers/md/dm-io.c

···
  * This file is released under the GPL.
  */
 
-#include "dm.h"
+#include "dm-core.h"
 
 #include <linux/device-mapper.h>
 

drivers/md/dm-ioctl.c

···
  * This file is released under the GPL.
  */
 
-#include "dm.h"
+#include "dm-core.h"
 
 #include <linux/module.h>
 #include <linux/vmalloc.h>
···
 	return dm_table_complete(table);
 }
 
+static bool is_valid_type(unsigned cur, unsigned new)
+{
+	if (cur == new ||
+	    (cur == DM_TYPE_BIO_BASED && new == DM_TYPE_DAX_BIO_BASED))
+		return true;
+
+	return false;
+}
+
 static int table_load(struct dm_ioctl *param, size_t param_size)
 {
 	int r;
···
 			DMWARN("unable to set up device queue for new table.");
 			goto err_unlock_md_type;
 		}
-	} else if (dm_get_md_type(md) != dm_table_get_type(t)) {
+	} else if (!is_valid_type(dm_get_md_type(md), dm_table_get_type(t))) {
 		DMWARN("can't change device type after initial table load.");
 		r = -EINVAL;
 		goto err_unlock_md_type;
···
 	return r;
 }
 
-#define DM_PARAMS_KMALLOC	0x0001	/* Params alloced with kmalloc */
-#define DM_PARAMS_VMALLOC	0x0002	/* Params alloced with vmalloc */
+#define DM_PARAMS_MALLOC	0x0001	/* Params allocated with kvmalloc() */
 #define DM_WIPE_BUFFER		0x0010	/* Wipe input buffer before returning from ioctl */
 
 static void free_params(struct dm_ioctl *param, size_t param_size, int param_flags)
···
 	if (param_flags & DM_WIPE_BUFFER)
 		memset(param, 0, param_size);
 
-	if (param_flags & DM_PARAMS_KMALLOC)
-		kfree(param);
-	if (param_flags & DM_PARAMS_VMALLOC)
-		vfree(param);
+	if (param_flags & DM_PARAMS_MALLOC)
+		kvfree(param);
 }
 
 static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
···
 	 * Use kmalloc() rather than vmalloc() when we can.
 	 */
 	dmi = NULL;
-	if (param_kernel->data_size <= KMALLOC_MAX_SIZE) {
+	if (param_kernel->data_size <= KMALLOC_MAX_SIZE)
 		dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
-		if (dmi)
-			*param_flags |= DM_PARAMS_KMALLOC;
-	}
 
 	if (!dmi) {
 		unsigned noio_flag;
 		noio_flag = memalloc_noio_save();
 		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
 		memalloc_noio_restore(noio_flag);
-		if (dmi)
-			*param_flags |= DM_PARAMS_VMALLOC;
 	}
 
 	if (!dmi) {
···
 			return -EFAULT;
 		return -ENOMEM;
 	}
+
+	*param_flags |= DM_PARAMS_MALLOC;
 
 	if (copy_from_user(dmi, user, param_kernel->data_size))
 		goto bad;

drivers/md/dm-kcopyd.c

···
 #include <linux/device-mapper.h>
 #include <linux/dm-kcopyd.h>
 
-#include "dm.h"
+#include "dm-core.h"
 
 #define SUB_JOB_SIZE	128
 #define SPLIT_COUNT	8

drivers/md/dm-linear.c

···
 	return fn(ti, lc->dev, lc->start, ti->len, data);
 }
 
+static long linear_direct_access(struct dm_target *ti, sector_t sector,
+				 void __pmem **kaddr, pfn_t *pfn, long size)
+{
+	struct linear_c *lc = ti->private;
+	struct block_device *bdev = lc->dev->bdev;
+	struct blk_dax_ctl dax = {
+		.sector = linear_map_sector(ti, sector),
+		.size = size,
+	};
+	long ret;
+
+	ret = bdev_direct_access(bdev, &dax);
+	*kaddr = dax.addr;
+	*pfn = dax.pfn;
+
+	return ret;
+}
+
 static struct target_type linear_target = {
 	.name   = "linear",
-	.version = {1, 2, 1},
+	.version = {1, 3, 0},
 	.module = THIS_MODULE,
 	.ctr    = linear_ctr,
 	.dtr    = linear_dtr,
···
 	.status = linear_status,
 	.prepare_ioctl = linear_prepare_ioctl,
 	.iterate_devices = linear_iterate_devices,
+	.direct_access = linear_direct_access,
 };
 
 int __init dm_linear_init(void)

drivers/md/dm-mpath.c

···
 
 #include <linux/device-mapper.h>
 
-#include "dm.h"
+#include "dm-rq.h"
+#include "dm-bio-record.h"
 #include "dm-path-selector.h"
 #include "dm-uevent.h"
 
···
 	atomic_t pg_init_in_progress;	/* Only one pg_init allowed at once */
 	atomic_t pg_init_count;		/* Number of times pg_init called */
 
+	unsigned queue_mode;
+
 	/*
 	 * We must use a mempool of dm_mpath_io structs so that we
 	 * can resubmit bios on error.
···
 
 	struct mutex work_mutex;
 	struct work_struct trigger_event;
+
+	struct work_struct process_queued_bios;
+	struct bio_list queued_bios;
 };
 
 /*
- * Context information attached to each bio we process.
+ * Context information attached to each io we process.
  */
 struct dm_mpath_io {
 	struct pgpath *pgpath;
···
 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
 static void trigger_event(struct work_struct *work);
 static void activate_path(struct work_struct *work);
+static void process_queued_bios(struct work_struct *work);
 
 /*-----------------------------------------------
  * Multipath state flags.
···
 	kfree(pg);
 }
 
-static struct multipath *alloc_multipath(struct dm_target *ti, bool use_blk_mq)
+static struct multipath *alloc_multipath(struct dm_target *ti)
 {
 	struct multipath *m;
 
···
 		mutex_init(&m->work_mutex);
 
 		m->mpio_pool = NULL;
-		if (!use_blk_mq) {
-			unsigned min_ios = dm_get_reserved_rq_based_ios();
-
-			m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
-			if (!m->mpio_pool) {
-				kfree(m);
-				return NULL;
-			}
-		}
+		m->queue_mode = DM_TYPE_NONE;
 
 		m->ti = ti;
 		ti->private = m;
 	}
 
 	return m;
+}
+
+static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
+{
+	if (m->queue_mode == DM_TYPE_NONE) {
+		/*
+		 * Default to request-based.
+		 */
+		if (dm_use_blk_mq(dm_table_get_md(ti->table)))
+			m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
+		else
+			m->queue_mode = DM_TYPE_REQUEST_BASED;
+	}
+
+	if (m->queue_mode == DM_TYPE_REQUEST_BASED) {
+		unsigned min_ios = dm_get_reserved_rq_based_ios();
+
+		m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
+		if (!m->mpio_pool)
+			return -ENOMEM;
+	}
+	else if (m->queue_mode == DM_TYPE_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);
+	}
+
+	dm_table_set_type(ti->table, m->queue_mode);
+
+	return 0;
 }
 
 static void free_multipath(struct multipath *m)
···
 		info->ptr = NULL;
 		mempool_free(mpio, m->mpio_pool);
 	}
+}
+
+static size_t multipath_per_bio_data_size(void)
+{
+	return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
+}
+
+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)
+{
+	/* 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)
+{
+	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);
+
+	if (mpio_p)
+		*mpio_p = mpio;
+	if (bio_details_p)
+		*bio_details_p = bio_details;
 }
 
 /*-----------------------------------------------
···
  * and multipath_resume() calls and we have no need to check
  * for the DMF_NOFLUSH_SUSPENDING flag.
  */
-static int must_push_back(struct multipath *m)
+static bool __must_push_back(struct multipath *m)
+{
+	return ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) !=
+		 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) &&
+		dm_noflush_suspending(m->ti));
+}
+
+static bool must_push_back_rq(struct multipath *m)
 {
 	return (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
-		((test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) !=
-		  test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) &&
-		 dm_noflush_suspending(m->ti)));
+		__must_push_back(m));
+}
+
+static bool must_push_back_bio(struct multipath *m)
+{
+	return __must_push_back(m);
 }
 
 /*
- * Map cloned requests
+ * Map cloned requests (request-based multipath)
  */
 static int __multipath_map(struct dm_target *ti, struct request *clone,
 			   union map_info *map_context,
···
 		pgpath = choose_pgpath(m, nr_bytes);
 
 	if (!pgpath) {
-		if (!must_push_back(m))
+		if (!must_push_back_rq(m))
 			r = -EIO;	/* Failed */
 		return r;
 	} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
···
 }
 
 /*
+ * Map cloned bios (bio-based multipath)
+ */
+static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)
+{
+	size_t nr_bytes = bio->bi_iter.bi_size;
+	struct pgpath *pgpath;
+	unsigned long flags;
+	bool queue_io;
+
+	/* Do we need to select a new pgpath? */
+	pgpath = lockless_dereference(m->current_pgpath);
+	queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
+	if (!pgpath || !queue_io)
+		pgpath = choose_pgpath(m, nr_bytes);
+
+	if ((pgpath && queue_io) ||
+	    (!pgpath && 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);
+		/* 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;
+	}
+
+	if (!pgpath) {
+		if (!must_push_back_bio(m))
+			return -EIO;
+		return DM_MAPIO_REQUEUE;
+	}
+
+	mpio->pgpath = pgpath;
+	mpio->nr_bytes = nr_bytes;
+
+	bio->bi_error = 0;
+	bio->bi_bdev = pgpath->path.dev->bdev;
+	bio->bi_rw |= REQ_FAILFAST_TRANSPORT;
+
+	if (pgpath->pg->ps.type->start_io)
+		pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
+					      &pgpath->path,
+					      nr_bytes);
+	return DM_MAPIO_REMAPPED;
+}
+
+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);
+
+	return __multipath_map_bio(m, bio, mpio);
+}
+
+static void process_queued_bios_list(struct multipath *m)
+{
+	if (m->queue_mode == DM_TYPE_BIO_BASED)
+		queue_work(kmultipathd, &m->process_queued_bios);
+}
+
+static void process_queued_bios(struct work_struct *work)
+{
+	int r;
+	unsigned long flags;
+	struct bio *bio;
+	struct bio_list bios;
+	struct blk_plug plug;
+	struct multipath *m =
+		container_of(work, struct multipath, process_queued_bios);
+
+	bio_list_init(&bios);
+
+	spin_lock_irqsave(&m->lock, flags);
+
+	if (bio_list_empty(&m->queued_bios)) {
+		spin_unlock_irqrestore(&m->lock, flags);
+		return;
+	}
+
+	bio_list_merge(&bios, &m->queued_bios);
+	bio_list_init(&m->queued_bios);
+
+	spin_unlock_irqrestore(&m->lock, flags);
+
+	blk_start_plug(&plug);
+	while ((bio = bio_list_pop(&bios))) {
+		r = __multipath_map_bio(m, bio, get_mpio_from_bio(bio));
+		if (r < 0 || r == DM_MAPIO_REQUEUE) {
+			bio->bi_error = r;
+			bio_endio(bio);
+		} else if (r == DM_MAPIO_REMAPPED)
+			generic_make_request(bio);
+	}
+	blk_finish_plug(&plug);
+}
+
+/*
  * If we run out of usable paths, should we queue I/O or error it?
  */
 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
···
 
 	spin_unlock_irqrestore(&m->lock, flags);
 
-	if (!queue_if_no_path)
+	if (!queue_if_no_path) {
 		dm_table_run_md_queue_async(m->ti->table);
+		process_queued_bios_list(m);
+	}
 
 	return 0;
 }
···
 	if (!hw_argc)
 		return 0;
 
+	if (m->queue_mode == DM_TYPE_BIO_BASED) {
+		dm_consume_args(as, hw_argc);
+		DMERR("bio-based multipath doesn't allow hardware handler args");
+		return 0;
+	}
+
 	m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
 
 	if (hw_argc > 1) {
···
 	const char *arg_name;
 
 	static struct dm_arg _args[] = {
-		{0, 6, "invalid number of feature args"},
+		{0, 8, "invalid number of feature args"},
 		{1, 50, "pg_init_retries must be between 1 and 50"},
 		{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
 	};
···
 			continue;
 		}
 
+		if (!strcasecmp(arg_name, "queue_mode") &&
+		    (argc >= 1)) {
+			const char *queue_mode_name = dm_shift_arg(as);
+
+			if (!strcasecmp(queue_mode_name, "bio"))
+				m->queue_mode = DM_TYPE_BIO_BASED;
+			else if (!strcasecmp(queue_mode_name, "rq"))
+				m->queue_mode = DM_TYPE_REQUEST_BASED;
+			else if (!strcasecmp(queue_mode_name, "mq"))
+				m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
+			else {
+				ti->error = "Unknown 'queue_mode' requested";
+				r = -EINVAL;
+			}
+			argc--;
+			continue;
+		}
+
 		ti->error = "Unrecognised multipath feature request";
 		r = -EINVAL;
 	} while (argc && !r);
···
 	return r;
 }
 
-static int multipath_ctr(struct dm_target *ti, unsigned int argc,
-			 char **argv)
+static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
 	/* target arguments */
 	static struct dm_arg _args[] = {
···
 	struct dm_arg_set as;
 	unsigned pg_count = 0;
 	unsigned next_pg_num;
-	bool use_blk_mq = dm_use_blk_mq(dm_table_get_md(ti->table));
 
 	as.argc = argc;
 	as.argv = argv;
 
-	m = alloc_multipath(ti, use_blk_mq);
+	m = alloc_multipath(ti);
 	if (!m) {
 		ti->error = "can't allocate multipath";
 		return -EINVAL;
 	}
 
 	r = parse_features(&as, m);
+	if (r)
+		goto bad;
+
+	r = alloc_multipath_stage2(ti, m);
 	if (r)
 		goto bad;
 
···
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->num_write_same_bios = 1;
-	if (use_blk_mq)
+	if (m->queue_mode == DM_TYPE_BIO_BASED)
+		ti->per_io_data_size = multipath_per_bio_data_size();
+	else if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
 		ti->per_io_data_size = sizeof(struct dm_mpath_io);
 
 	return 0;
···
 
 out:
 	spin_unlock_irqrestore(&m->lock, flags);
-	if (run_queue)
+	if (run_queue) {
 		dm_table_run_md_queue_async(m->ti->table);
+		process_queued_bios_list(m);
+	}
 
 	return r;
 }
···
 	}
 	clear_bit(MPATHF_QUEUE_IO, &m->flags);
 
+	process_queued_bios_list(m);
+
 	/*
 	 * Wake up any thread waiting to suspend.
 	 */
···
 	 * during end I/O handling, since those clone requests don't have
 	 * bio clones.  If we queue them inside the multipath target,
 	 * we need to make bio clones, that requires memory allocation.
-	 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
+	 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
 	 *  don't have bio clones.)
 	 * Instead of queueing the clone request here, we queue the original
 	 * request into dm core, which will remake a clone request and
···
 
 	if (!atomic_read(&m->nr_valid_paths)) {
 		if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
-			if (!must_push_back(m))
+			if (!must_push_back_rq(m))
 				r = -EIO;
 		} else {
 			if (error == -EBADE)
···
 			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
 	}
 	clear_request_fn_mpio(m, map_context);
+
+	return r;
+}
+
+static int do_end_io_bio(struct multipath *m, struct bio *clone,
+			 int error, struct dm_mpath_io *mpio)
+{
+	unsigned long flags;
+
+	if (!error)
+		return 0;	/* I/O complete */
+
+	if (noretry_error(error))
+		return error;
+
+	if (mpio->pgpath)
+		fail_path(mpio->pgpath);
+
+	if (!atomic_read(&m->nr_valid_paths)) {
+		if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
+			if (!must_push_back_bio(m))
+				return -EIO;
+			return DM_ENDIO_REQUEUE;
+		} else {
+			if (error == -EBADE)
+				return error;
+		}
+	}
+
+	/* 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);
+	if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
+		queue_work(kmultipathd, &m->process_queued_bios);
+
+	return DM_ENDIO_INCOMPLETE;
+}
+
+static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone, int error)
+{
+	struct multipath *m = ti->private;
+	struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
+	struct pgpath *pgpath;
+	struct path_selector *ps;
+	int r;
+
+	BUG_ON(!mpio);
+
+	r = do_end_io_bio(m, clone, error, mpio);
+	pgpath = mpio->pgpath;
+	if (pgpath) {
+		ps = &pgpath->pg->ps;
+		if (ps->type->end_io)
+			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
+	}
 
 	return r;
 }
···
 		DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
 			      (m->pg_init_retries > 0) * 2 +
 			      (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
-			      test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags));
+			      test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
+			      (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
+
 		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
 			DMEMIT("queue_if_no_path ");
 		if (m->pg_init_retries)
···
 			DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
 		if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
 			DMEMIT("retain_attached_hw_handler ");
+		if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
+			switch(m->queue_mode) {
+			case DM_TYPE_BIO_BASED:
+				DMEMIT("queue_mode bio ");
+				break;
+			case DM_TYPE_MQ_REQUEST_BASED:
+				DMEMIT("queue_mode mq ");
+				break;
+			}
+		}
 	}
 
 	if (!m->hw_handler_name || type == STATUSTYPE_INFO)
···
 		if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
 			pg_init_all_paths(m);
 		dm_table_run_md_queue_async(m->ti->table);
+		process_queued_bios_list(m);
 	}
 
 	/*
···
  *---------------------------------------------------------------*/
 static struct target_type multipath_target = {
 	.name = "multipath",
-	.version = {1, 11, 0},
+	.version = {1, 12, 0},
 	.features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
 	.module = THIS_MODULE,
 	.ctr = multipath_ctr,
···
 	.clone_and_map_rq = multipath_clone_and_map,
 	.release_clone_rq = multipath_release_clone,
 	.rq_end_io = multipath_end_io,
+	.map = multipath_map_bio,
+	.end_io = multipath_end_io_bio,
 	.presuspend = multipath_presuspend,
 	.postsuspend = multipath_postsuspend,
 	.resume = multipath_resume,
···
 {
 	int r;
 
-	/* allocate a slab for the dm_ios */
+	/* allocate a slab for the dm_mpath_ios */
 	_mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
 	if (!_mpio_cache)
 		return -ENOMEM;
 
 	r = dm_register_target(&multipath_target);
 	if (r < 0) {
-		DMERR("register failed %d", r);
+		DMERR("request-based register failed %d", r);
 		r = -EINVAL;
 		goto bad_register_target;
 	}
···
 		r = -ENOMEM;
 		goto bad_alloc_kmpath_handlerd;
 	}
-
-	DMINFO("version %u.%u.%u loaded",
-	       multipath_target.version[0], multipath_target.version[1],
-	       multipath_target.version[2]);
 
 	return 0;
 

drivers/md/dm-raid.c

···
 /*
  * Copyright (C) 2010-2011 Neil Brown
- * Copyright (C) 2010-2015 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2010-2016 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the GPL.
  */
···
 #include <linux/device-mapper.h>
 
 #define DM_MSG_PREFIX "raid"
-#define	MAX_RAID_DEVICES	253 /* raid4/5/6 limit */
+#define	MAX_RAID_DEVICES	253 /* md-raid kernel limit */
+
+/*
+ * Minimum sectors of free reshape space per raid device
+ */
+#define	MIN_FREE_RESHAPE_SPACE to_sector(4*4096)
 
 static bool devices_handle_discard_safely = false;
 
···
  * The following flags are used by dm-raid.c to set up the array state.
  * They must be cleared before md_run is called.
  */
-#define FirstUse 10             /* rdev flag */
+#define FirstUse 10		/* rdev flag */
 
 struct raid_dev {
 	/*
 	 * Two DM devices, one to hold metadata and one to hold the
-	 * actual data/parity.  The reason for this is to not confuse
+	 * actual data/parity.	The reason for this is to not confuse
 	 * ti->len and give more flexibility in altering size and
 	 * characteristics.
 	 *
···
 };
 
 /*
+ * Bits for establishing rs->ctr_flags
+ *
+ * 1 = no flag value
+ * 2 = flag with value
+ */
+#define __CTR_FLAG_SYNC			0  /* 1 */ /* Not with raid0! */
+#define __CTR_FLAG_NOSYNC		1  /* 1 */ /* Not with raid0! */
+#define __CTR_FLAG_REBUILD		2  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_DAEMON_SLEEP		3  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_MIN_RECOVERY_RATE	4  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_MAX_RECOVERY_RATE	5  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_MAX_WRITE_BEHIND	6  /* 2 */ /* Only with raid1! */
+#define __CTR_FLAG_WRITE_MOSTLY		7  /* 2 */ /* Only with raid1! */
+#define __CTR_FLAG_STRIPE_CACHE		8  /* 2 */ /* Only with raid4/5/6! */
+#define __CTR_FLAG_REGION_SIZE		9  /* 2 */ /* Not with raid0! */
+#define __CTR_FLAG_RAID10_COPIES	10 /* 2 */ /* Only with raid10 */
+#define __CTR_FLAG_RAID10_FORMAT	11 /* 2 */ /* Only with raid10 */
+/* New for v1.9.0 */
+#define __CTR_FLAG_DELTA_DISKS		12 /* 2 */ /* Only with reshapable raid1/4/5/6/10! */
+#define __CTR_FLAG_DATA_OFFSET		13 /* 2 */ /* Only with reshapable raid4/5/6/10! */
+#define __CTR_FLAG_RAID10_USE_NEAR_SETS 14 /* 2 */ /* Only with raid10! */
+
+/*
  * Flags for rs->ctr_flags field.
  */
-#define CTR_FLAG_SYNC              0x1
-#define CTR_FLAG_NOSYNC            0x2
-#define CTR_FLAG_REBUILD           0x4
-#define CTR_FLAG_DAEMON_SLEEP      0x8
-#define CTR_FLAG_MIN_RECOVERY_RATE 0x10
-#define CTR_FLAG_MAX_RECOVERY_RATE 0x20
-#define CTR_FLAG_MAX_WRITE_BEHIND  0x40
-#define CTR_FLAG_STRIPE_CACHE      0x80
-#define CTR_FLAG_REGION_SIZE       0x100
-#define CTR_FLAG_RAID10_COPIES     0x200
-#define CTR_FLAG_RAID10_FORMAT     0x400
+#define CTR_FLAG_SYNC			(1 << __CTR_FLAG_SYNC)
+#define CTR_FLAG_NOSYNC			(1 << __CTR_FLAG_NOSYNC)
+#define CTR_FLAG_REBUILD		(1 << __CTR_FLAG_REBUILD)
+#define CTR_FLAG_DAEMON_SLEEP		(1 << __CTR_FLAG_DAEMON_SLEEP)
+#define CTR_FLAG_MIN_RECOVERY_RATE	(1 << __CTR_FLAG_MIN_RECOVERY_RATE)
+#define CTR_FLAG_MAX_RECOVERY_RATE	(1 << __CTR_FLAG_MAX_RECOVERY_RATE)
+#define CTR_FLAG_MAX_WRITE_BEHIND	(1 << __CTR_FLAG_MAX_WRITE_BEHIND)
+#define CTR_FLAG_WRITE_MOSTLY		(1 << __CTR_FLAG_WRITE_MOSTLY)
+#define CTR_FLAG_STRIPE_CACHE		(1 << __CTR_FLAG_STRIPE_CACHE)
+#define CTR_FLAG_REGION_SIZE		(1 << __CTR_FLAG_REGION_SIZE)
+#define CTR_FLAG_RAID10_COPIES		(1 << __CTR_FLAG_RAID10_COPIES)
+#define CTR_FLAG_RAID10_FORMAT		(1 << __CTR_FLAG_RAID10_FORMAT)
+#define CTR_FLAG_DELTA_DISKS		(1 << __CTR_FLAG_DELTA_DISKS)
+#define CTR_FLAG_DATA_OFFSET		(1 << __CTR_FLAG_DATA_OFFSET)
+#define CTR_FLAG_RAID10_USE_NEAR_SETS	(1 << __CTR_FLAG_RAID10_USE_NEAR_SETS)
+
+/*
+ * Definitions of various constructor flags to
+ * be used in checks of valid / invalid flags
+ * per raid level.
+ */
+/* Define all any sync flags */
+#define	CTR_FLAGS_ANY_SYNC		(CTR_FLAG_SYNC | CTR_FLAG_NOSYNC)
+
+/* Define flags for options without argument (e.g. 'nosync') */
+#define	CTR_FLAG_OPTIONS_NO_ARGS	(CTR_FLAGS_ANY_SYNC | \
+					 CTR_FLAG_RAID10_USE_NEAR_SETS)
+
+/* Define flags for options with one argument (e.g. 'delta_disks +2') */
+#define CTR_FLAG_OPTIONS_ONE_ARG (CTR_FLAG_REBUILD | \
+				  CTR_FLAG_WRITE_MOSTLY | \
+				  CTR_FLAG_DAEMON_SLEEP | \
+				  CTR_FLAG_MIN_RECOVERY_RATE | \
+				  CTR_FLAG_MAX_RECOVERY_RATE | \
+				  CTR_FLAG_MAX_WRITE_BEHIND | \
+				  CTR_FLAG_STRIPE_CACHE | \
+				  CTR_FLAG_REGION_SIZE | \
+				  CTR_FLAG_RAID10_COPIES | \
+				  CTR_FLAG_RAID10_FORMAT | \
+				  CTR_FLAG_DELTA_DISKS | \
+				  CTR_FLAG_DATA_OFFSET)
+
+/* Valid options definitions per raid level... */
+
+/* "raid0" does only accept data offset */
+#define RAID0_VALID_FLAGS	(CTR_FLAG_DATA_OFFSET)
+
+/* "raid1" does not accept stripe cache, data offset, delta_disks or any raid10 options */
+#define RAID1_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
+				 CTR_FLAG_REBUILD | \
+				 CTR_FLAG_WRITE_MOSTLY | \
+				 CTR_FLAG_DAEMON_SLEEP | \
+				 CTR_FLAG_MIN_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_WRITE_BEHIND | \
+				 CTR_FLAG_REGION_SIZE | \
+				 CTR_FLAG_DELTA_DISKS | \
+				 CTR_FLAG_DATA_OFFSET)
+
+/* "raid10" does not accept any raid1 or stripe cache options */
+#define RAID10_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
+				 CTR_FLAG_REBUILD | \
+				 CTR_FLAG_DAEMON_SLEEP | \
+				 CTR_FLAG_MIN_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_RECOVERY_RATE | \
+				 CTR_FLAG_REGION_SIZE | \
+				 CTR_FLAG_RAID10_COPIES | \
+				 CTR_FLAG_RAID10_FORMAT | \
+				 CTR_FLAG_DELTA_DISKS | \
+				 CTR_FLAG_DATA_OFFSET | \
+				 CTR_FLAG_RAID10_USE_NEAR_SETS)
+
+/*
+ * "raid4/5/6" do not accept any raid1 or raid10 specific options
+ *
+ * "raid6" does not accept "nosync", because it is not guaranteed
+ * that both parity and q-syndrome are being written properly with
+ * any writes
+ */
+#define RAID45_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
+				 CTR_FLAG_REBUILD | \
+				 CTR_FLAG_DAEMON_SLEEP | \
+				 CTR_FLAG_MIN_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_WRITE_BEHIND | \
+				 CTR_FLAG_STRIPE_CACHE | \
+				 CTR_FLAG_REGION_SIZE | \
+				 CTR_FLAG_DELTA_DISKS | \
+				 CTR_FLAG_DATA_OFFSET)
+
+#define RAID6_VALID_FLAGS	(CTR_FLAG_SYNC | \
+				 CTR_FLAG_REBUILD | \
+				 CTR_FLAG_DAEMON_SLEEP | \
+				 CTR_FLAG_MIN_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_RECOVERY_RATE | \
+				 CTR_FLAG_MAX_WRITE_BEHIND | \
+				 CTR_FLAG_STRIPE_CACHE | \
+				 CTR_FLAG_REGION_SIZE | \
+				 CTR_FLAG_DELTA_DISKS | \
+				 CTR_FLAG_DATA_OFFSET)
+/* ...valid options definitions per raid level */
+
+/*
+ * Flags for rs->runtime_flags field
+ * (RT_FLAG prefix meaning "runtime flag")
+ *
+ * These are all internal and used to define runtime state,
+ * e.g. to prevent another resume from preresume processing
+ * the raid set all over again.
+ */
+#define RT_FLAG_RS_PRERESUMED		0
+#define RT_FLAG_RS_RESUMED		1
+#define RT_FLAG_RS_BITMAP_LOADED	2
+#define RT_FLAG_UPDATE_SBS		3
+#define RT_FLAG_RESHAPE_RS		4
+#define RT_FLAG_KEEP_RS_FROZEN		5
+
+/* Array elements of 64 bit needed for rebuild/failed disk bits */
+#define DISKS_ARRAY_ELEMS ((MAX_RAID_DEVICES + (sizeof(uint64_t) * 8 - 1)) / sizeof(uint64_t) / 8)
+
+/*
+ * raid set level, layout and chunk sectors backup/restore
+ */
+struct rs_layout {
+	int new_level;
+	int new_layout;
+	int new_chunk_sectors;
+};
 
 struct raid_set {
 	struct dm_target *ti;
 
 	uint32_t bitmap_loaded;
-	uint32_t ctr_flags;
+	uint32_t stripe_cache_entries;
+	unsigned long ctr_flags;
+	unsigned long runtime_flags;
+
+	uint64_t rebuild_disks[DISKS_ARRAY_ELEMS];
+
+	int raid_disks;
+	int delta_disks;
+	int data_offset;
+	int raid10_copies;
+	int requested_bitmap_chunk_sectors;
 
 	struct mddev md;
 	struct raid_type *raid_type;
···
 	struct raid_dev dev[0];
 };
 
+static void rs_config_backup(struct raid_set *rs, struct rs_layout *l)
+{
+	struct mddev *mddev = &rs->md;
+
+	l->new_level = mddev->new_level;
+	l->new_layout = mddev->new_layout;
+	l->new_chunk_sectors = mddev->new_chunk_sectors;
+}
+
+static void rs_config_restore(struct raid_set *rs, struct rs_layout *l)
+{
+	struct mddev *mddev = &rs->md;
+
+	mddev->new_level = l->new_level;
+	mddev->new_layout = l->new_layout;
+	mddev->new_chunk_sectors = l->new_chunk_sectors;
+}
+
+/* raid10 algorithms (i.e. formats) */
+#define	ALGORITHM_RAID10_DEFAULT	0
+#define	ALGORITHM_RAID10_NEAR		1
+#define	ALGORITHM_RAID10_OFFSET		2
+#define	ALGORITHM_RAID10_FAR		3
+
 /* Supported raid types and properties. */
 static struct raid_type {
 	const char *name;		/* RAID algorithm. */
 	const char *descr;		/* Descriptor text for logging. */
-	const unsigned parity_devs;	/* # of parity devices. */
-	const unsigned minimal_devs;	/* minimal # of devices in set. */
-	const unsigned level;		/* RAID level. */
-	const unsigned algorithm;	/* RAID algorithm. */
+	const unsigned int parity_devs;	/* # of parity devices. */
+	const unsigned int minimal_devs;/* minimal # of devices in set. */
+	const unsigned int level;	/* RAID level. */
+	const unsigned int algorithm;	/* RAID algorithm. */
 } raid_types[] = {
-	{"raid0",    "RAID0 (striping)",                0, 2, 0, 0 /* NONE */},
-	{"raid1",    "RAID1 (mirroring)",               0, 2, 1, 0 /* NONE */},
-	{"raid10",   "RAID10 (striped mirrors)",        0, 2, 10, UINT_MAX /* Varies */},
-	{"raid4",    "RAID4 (dedicated parity disk)",	1, 2, 5, ALGORITHM_PARITY_0},
-	{"raid5_la", "RAID5 (left asymmetric)",		1, 2, 5, ALGORITHM_LEFT_ASYMMETRIC},
-	{"raid5_ra", "RAID5 (right asymmetric)",	1, 2, 5, ALGORITHM_RIGHT_ASYMMETRIC},
-	{"raid5_ls", "RAID5 (left symmetric)",		1, 2, 5, ALGORITHM_LEFT_SYMMETRIC},
-	{"raid5_rs", "RAID5 (right symmetric)",		1, 2, 5, ALGORITHM_RIGHT_SYMMETRIC},
-	{"raid6_zr", "RAID6 (zero restart)",		2, 4, 6, ALGORITHM_ROTATING_ZERO_RESTART},
-	{"raid6_nr", "RAID6 (N restart)",		2, 4, 6, ALGORITHM_ROTATING_N_RESTART},
-	{"raid6_nc", "RAID6 (N continue)",		2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE}
+	{"raid0",	  "raid0 (striping)",			    0, 2, 0,  0 /* NONE */},
+	{"raid1",	  "raid1 (mirroring)",			    0, 2, 1,  0 /* NONE */},
+	{"raid10_far",	  "raid10 far (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_FAR},
+	{"raid10_offset", "raid10 offset (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_OFFSET},
+	{"raid10_near",	  "raid10 near (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_NEAR},
+	{"raid10",	  "raid10 (striped mirrors)",		    0, 2, 10, ALGORITHM_RAID10_DEFAULT},
+	{"raid4",	  "raid4 (dedicated last parity disk)",	    1, 2, 4,  ALGORITHM_PARITY_N}, /* raid4 layout = raid5_n */
+	{"raid5_n",	  "raid5 (dedicated last parity disk)",	    1, 2, 5,  ALGORITHM_PARITY_N},
+	{"raid5_ls",	  "raid5 (left symmetric)",		    1, 2, 5,  ALGORITHM_LEFT_SYMMETRIC},
+	{"raid5_rs",	  "raid5 (right symmetric)",		    1, 2, 5,  ALGORITHM_RIGHT_SYMMETRIC},
+	{"raid5_la",	  "raid5 (left asymmetric)",		    1, 2, 5,  ALGORITHM_LEFT_ASYMMETRIC},
+	{"raid5_ra",	  "raid5 (right asymmetric)",		    1, 2, 5,  ALGORITHM_RIGHT_ASYMMETRIC},
+	{"raid6_zr",	  "raid6 (zero restart)",		    2, 4, 6,  ALGORITHM_ROTATING_ZERO_RESTART},
+	{"raid6_nr",	  "raid6 (N restart)",			    2, 4, 6,  ALGORITHM_ROTATING_N_RESTART},
+	{"raid6_nc",	  "raid6 (N continue)",			    2, 4, 6,  ALGORITHM_ROTATING_N_CONTINUE},
+	{"raid6_n_6",	  "raid6 (dedicated parity/Q n/6)",	    2, 4, 6,  ALGORITHM_PARITY_N_6},
+	{"raid6_ls_6",	  "raid6 (left symmetric dedicated Q 6)",   2, 4, 6,  ALGORITHM_LEFT_SYMMETRIC_6},
+	{"raid6_rs_6",	  "raid6 (right symmetric dedicated Q 6)",  2, 4, 6,  ALGORITHM_RIGHT_SYMMETRIC_6},
+	{"raid6_la_6",	  "raid6 (left asymmetric dedicated Q 6)",  2, 4, 6,  ALGORITHM_LEFT_ASYMMETRIC_6},
+	{"raid6_ra_6",	  "raid6 (right asymmetric dedicated Q 6)", 2, 4, 6,  ALGORITHM_RIGHT_ASYMMETRIC_6}
 };
 
-static char *raid10_md_layout_to_format(int layout)
+/* True, if @v is in inclusive range [@min, @max] */
+static bool __within_range(long v, long min, long max)
 {
-	/*
-	 * Bit 16 and 17 stand for "offset" and "use_far_sets"
-	 * Refer to MD's raid10.c for details
-	 */
-	if ((layout & 0x10000) && (layout & 0x20000))
-		return "offset";
-
-	if ((layout & 0xFF) > 1)
-		return "near";
-
-	return "far";
+	return v >= min && v <= max;
 }
 
-static unsigned raid10_md_layout_to_copies(int layout)
+/* All table line arguments are defined here */
+static struct arg_name_flag {
+	const unsigned long flag;
+	const char *name;
+} __arg_name_flags[] = {
+	{ CTR_FLAG_SYNC, "sync"},
+	{ CTR_FLAG_NOSYNC, "nosync"},
+	{ CTR_FLAG_REBUILD, "rebuild"},
+	{ CTR_FLAG_DAEMON_SLEEP, "daemon_sleep"},
+	{ CTR_FLAG_MIN_RECOVERY_RATE, "min_recovery_rate"},
+	{ CTR_FLAG_MAX_RECOVERY_RATE, "max_recovery_rate"},
+	{ CTR_FLAG_MAX_WRITE_BEHIND, "max_write_behind"},
+	{ CTR_FLAG_WRITE_MOSTLY, "write_mostly"},
+	{ CTR_FLAG_STRIPE_CACHE, "stripe_cache"},
+	{ CTR_FLAG_REGION_SIZE, "region_size"},
+	{ CTR_FLAG_RAID10_COPIES, "raid10_copies"},
+	{ CTR_FLAG_RAID10_FORMAT, "raid10_format"},
+	{ CTR_FLAG_DATA_OFFSET, "data_offset"},
+	{ CTR_FLAG_DELTA_DISKS, "delta_disks"},
+	{ CTR_FLAG_RAID10_USE_NEAR_SETS, "raid10_use_near_sets"},
+};
+
+/* Return argument name string for given @flag */
+static const char *dm_raid_arg_name_by_flag(const uint32_t flag)
 {
-	if ((layout & 0xFF) > 1)
-		return layout & 0xFF;
-	return (layout >> 8) & 0xFF;
-}
+	if (hweight32(flag) == 1) {
+		struct arg_name_flag *anf = __arg_name_flags + ARRAY_SIZE(__arg_name_flags);
 
-static int raid10_format_to_md_layout(char *format, unsigned copies)
-{
-	unsigned n = 1, f = 1;
+		while (anf-- > __arg_name_flags)
+			if (flag & anf->flag)
+				return anf->name;
 
-	if (!strcasecmp("near", format))
-		n = copies;
-	else
-		f = copies;
-
-	if (!strcasecmp("offset", format))
-		return 0x30000 | (f << 8) | n;
-
-	if (!strcasecmp("far", format))
-		return 0x20000 | (f << 8) | n;
-
-	return (f << 8) | n;
-}
-
-static struct raid_type *get_raid_type(char *name)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(raid_types); i++)
-		if (!strcmp(raid_types[i].name, name))
-			return &raid_types[i];
+	} else
+		DMERR("%s called with more than one flag!", __func__);
 
 	return NULL;
 }
 
-static struct raid_set *context_alloc(struct dm_target *ti, struct raid_type *raid_type, unsigned raid_devs)
+/*
+ * Bool helpers to test for various raid levels of a raid set.
+ * It's level as reported by the superblock rather than
+ * the requested raid_type passed to the constructor.
+ */
+/* Return true, if raid set in @rs is raid0 */
+static bool rs_is_raid0(struct raid_set *rs)
 {
-	unsigned i;
+	return !rs->md.level;
+}
+
+/* Return true, if raid set in @rs is raid1 */
+static bool rs_is_raid1(struct raid_set *rs)
+{
+	return rs->md.level == 1;
+}
+
+/* Return true, if raid set in @rs is raid10 */
+static bool rs_is_raid10(struct raid_set *rs)
+{
+	return rs->md.level == 10;
+}
+
+/* Return true, if raid set in @rs is level 6 */
+static bool rs_is_raid6(struct raid_set *rs)
+{
+	return rs->md.level == 6;
+}
+
+/* Return true, if raid set in @rs is level 4, 5 or 6 */
+static bool rs_is_raid456(struct raid_set *rs)
+{
+	return __within_range(rs->md.level, 4, 6);
+}
+
+/* Return true, if raid set in @rs is reshapable */
+static bool __is_raid10_far(int layout);
+static bool rs_is_reshapable(struct raid_set *rs)
+{
+	return rs_is_raid456(rs) ||
+	       (rs_is_raid10(rs) && !__is_raid10_far(rs->md.new_layout));
+}
+
+/* Return true, if raid set in @rs is recovering */
+static bool rs_is_recovering(struct raid_set *rs)
+{
+	return rs->md.recovery_cp < rs->dev[0].rdev.sectors;
+}
+
+/* Return true, if raid set in @rs is reshaping */
+static bool rs_is_reshaping(struct raid_set *rs)
+{
+	return rs->md.reshape_position != MaxSector;
+}
+
+/*
+ * bool helpers to test for various raid levels of a raid type @rt
+ */
+
+/* Return true, if raid type in @rt is raid0 */
+static bool rt_is_raid0(struct raid_type *rt)
+{
+	return !rt->level;
+}
+
+/* Return true, if raid type in @rt is raid1 */
+static bool rt_is_raid1(struct raid_type *rt)
+{
+	return rt->level == 1;
+}
+
+/* Return true, if raid type in @rt is raid10 */
+static bool rt_is_raid10(struct raid_type *rt)
+{
+	return rt->level == 10;
+}
+
+/* Return true, if raid type in @rt is raid4/5 */
+static bool rt_is_raid45(struct raid_type *rt)
+{
+	return __within_range(rt->level, 4, 5);
+}
+
+/* Return true, if raid type in @rt is raid6 */
+static bool rt_is_raid6(struct raid_type *rt)
+{
+	return rt->level == 6;
+}
+
+/* Return true, if raid type in @rt is raid4/5/6 */
+static bool rt_is_raid456(struct raid_type *rt)
+{
+	return __within_range(rt->level, 4, 6);
+}
+/* END: raid level bools */
+
+/* Return valid ctr flags for the raid level of @rs */
+static unsigned long __valid_flags(struct raid_set *rs)
+{
+	if (rt_is_raid0(rs->raid_type))
+		return RAID0_VALID_FLAGS;
+	else if (rt_is_raid1(rs->raid_type))
+		return RAID1_VALID_FLAGS;
+	else if (rt_is_raid10(rs->raid_type))
+		return RAID10_VALID_FLAGS;
+	else if (rt_is_raid45(rs->raid_type))
+		return RAID45_VALID_FLAGS;
+	else if (rt_is_raid6(rs->raid_type))
+		return RAID6_VALID_FLAGS;
+
+	return 0;
+}
+
+/*
+ * Check for valid flags set on @rs
+ *
+ * Has to be called after parsing of the ctr flags!
+ */
+static int rs_check_for_valid_flags(struct raid_set *rs)
+{
+	if (rs->ctr_flags & ~__valid_flags(rs)) {
+		rs->ti->error = "Invalid flags combination";
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* MD raid10 bit definitions and helpers */
+#define RAID10_OFFSET			(1 << 16) /* stripes with data copies area adjacent on devices */
+#define RAID10_BROCKEN_USE_FAR_SETS	(1 << 17) /* Broken in raid10.c: use sets instead of whole stripe rotation */
+#define RAID10_USE_FAR_SETS		(1 << 18) /* Use sets instead of whole stripe rotation */
+#define RAID10_FAR_COPIES_SHIFT		8	  /* raid10 # far copies shift (2nd byte of layout) */
+
+/* Return md raid10 near copies for @layout */
+static unsigned int __raid10_near_copies(int layout)
+{
+	return layout & 0xFF;
+}
+
+/* Return md raid10 far copies for @layout */
+static unsigned int __raid10_far_copies(int layout)
+{
+	return __raid10_near_copies(layout >> RAID10_FAR_COPIES_SHIFT);
+}
+
+/* Return true if md raid10 offset for @layout */
+static bool __is_raid10_offset(int layout)
+{
+	return !!(layout & RAID10_OFFSET);
+}
+
+/* Return true if md raid10 near for @layout */
+static bool __is_raid10_near(int layout)
+{
+	return !__is_raid10_offset(layout) && __raid10_near_copies(layout) > 1;
+}
+
+/* Return true if md raid10 far for @layout */
+static bool __is_raid10_far(int layout)
+{
+	return !__is_raid10_offset(layout) && __raid10_far_copies(layout) > 1;
+}
+
+/* Return md raid10 layout string for @layout */
+static const char *raid10_md_layout_to_format(int layout)
+{
+	/*
+	 * Bit 16 stands for "offset"
+	 * (i.e. adjacent stripes hold copies)
+	 *
+	 * Refer to MD's raid10.c for details
+	 */
+	if (__is_raid10_offset(layout))
+		return "offset";
+
+	if (__raid10_near_copies(layout) > 1)
+		return "near";
+
+	WARN_ON(__raid10_far_copies(layout) < 2);
+
+	return "far";
+}
+
+/* Return md raid10 algorithm for @name */
+static int raid10_name_to_format(const char *name)
+{
+	if (!strcasecmp(name, "near"))
+		return ALGORITHM_RAID10_NEAR;
+	else if (!strcasecmp(name, "offset"))
+		return ALGORITHM_RAID10_OFFSET;
+	else if (!strcasecmp(name, "far"))
+		return ALGORITHM_RAID10_FAR;
+
+	return -EINVAL;
+}
+
+/* Return md raid10 copies for @layout */
+static unsigned int raid10_md_layout_to_copies(int layout)
+{
+	return max(__raid10_near_copies(layout), __raid10_far_copies(layout));
+}
+
+/* Return md raid10 format id for @format string */
+static int raid10_format_to_md_layout(struct raid_set *rs,
+				      unsigned int algorithm,
+				      unsigned int copies)
+{
+	unsigned int n = 1, f = 1, r = 0;
+
+	/*
+	 * MD resilienece flaw:
+	 *
+	 * enabling use_far_sets for far/offset formats causes copies
+	 * to be colocated on the same devs together with their origins!
+	 *
+	 * -> disable it for now in the definition above
+	 */
+	if (algorithm == ALGORITHM_RAID10_DEFAULT ||
+	    algorithm == ALGORITHM_RAID10_NEAR)
+		n = copies;
+
+	else if (algorithm == ALGORITHM_RAID10_OFFSET) {
+		f = copies;
+		r = RAID10_OFFSET;
+		if (!test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags))
+			r |= RAID10_USE_FAR_SETS;
+
+	} else if (algorithm == ALGORITHM_RAID10_FAR) {
+		f = copies;
+		r = !RAID10_OFFSET;
+		if (!test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags))
+			r |= RAID10_USE_FAR_SETS;
+
+	} else
+		return -EINVAL;
+
+	return r | (f << RAID10_FAR_COPIES_SHIFT) | n;
+}
+/* END: MD raid10 bit definitions and helpers */
+
+/* Check for any of the raid10 algorithms */
+static bool __got_raid10(struct raid_type *rtp, const int layout)
+{
+	if (rtp->level == 10) {
+		switch (rtp->algorithm) {
+		case ALGORITHM_RAID10_DEFAULT:
+		case ALGORITHM_RAID10_NEAR:
+			return __is_raid10_near(layout);
+		case ALGORITHM_RAID10_OFFSET:
+			return __is_raid10_offset(layout);
+		case ALGORITHM_RAID10_FAR:
+			return __is_raid10_far(layout);
+		default:
+			break;
+		}
+	}
+
+	return false;
+}
+
+/* Return raid_type for @name */
+static struct raid_type *get_raid_type(const char *name)
+{
+	struct raid_type *rtp = raid_types + ARRAY_SIZE(raid_types);
+
+	while (rtp-- > raid_types)
+		if (!strcasecmp(rtp->name, name))
+			return rtp;
+
+	return NULL;
+}
+
+/* Return raid_type for @name based derived from @level and @layout */
+static struct raid_type *get_raid_type_by_ll(const int level, const int layout)
+{
+	struct raid_type *rtp = raid_types + ARRAY_SIZE(raid_types);
+
+	while (rtp-- > raid_types) {
+		/* RAID10 special checks based on @layout flags/properties */
+		if (rtp->level == level &&
+		    (__got_raid10(rtp, layout) || rtp->algorithm == layout))
+			return rtp;
+	}
+
+	return NULL;
+}
+
+/*
+ * Conditionally change bdev capacity of @rs
+ * in case of a disk add/remove reshape
+ */
+static void rs_set_capacity(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *rdev;
+	struct gendisk *gendisk = dm_disk(dm_table_get_md(rs->ti->table));
+
+	/*
+	 * raid10 sets rdev->sector to the device size, which
+	 * is unintended in case of out-of-place reshaping
+	 */
+	rdev_for_each(rdev, mddev)
+		rdev->sectors = mddev->dev_sectors;
+
+	set_capacity(gendisk, mddev->array_sectors);
+	revalidate_disk(gendisk);
+}
+
+/*
+ * Set the mddev properties in @rs to the current
+ * ones retrieved from the freshest superblock
+ */
+static void rs_set_cur(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+
+	mddev->new_level = mddev->level;
+	mddev->new_layout = mddev->layout;
+	mddev->new_chunk_sectors = mddev->chunk_sectors;
+}
+
+/*
+ * Set the mddev properties in @rs to the new
+ * ones requested by the ctr
+ */
+static void rs_set_new(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+
+	mddev->level = mddev->new_level;
+	mddev->layout = mddev->new_layout;
+	mddev->chunk_sectors = mddev->new_chunk_sectors;
+	mddev->raid_disks = rs->raid_disks;
+	mddev->delta_disks = 0;
+}
+
+static struct raid_set *raid_set_alloc(struct dm_target *ti, struct raid_type *raid_type,
+				       unsigned int raid_devs)
+{
+	unsigned int i;
 	struct raid_set *rs;
 
 	if (raid_devs <= raid_type->parity_devs) {
···
 
 	mddev_init(&rs->md);
 
+	rs->raid_disks = raid_devs;
+	rs->delta_disks = 0;
+
 	rs->ti = ti;
 	rs->raid_type = raid_type;
+	rs->stripe_cache_entries = 256;
 	rs->md.raid_disks = raid_devs;
 	rs->md.level = raid_type->level;
 	rs->md.new_level = rs->md.level;
 	rs->md.layout = raid_type->algorithm;
 	rs->md.new_layout = rs->md.layout;
 	rs->md.delta_disks = 0;
-	rs->md.recovery_cp = 0;
+	rs->md.recovery_cp = MaxSector;
 
 	for (i = 0; i < raid_devs; i++)
 		md_rdev_init(&rs->dev[i].rdev);
···
 	return rs;
 }
 
-static void context_free(struct raid_set *rs)
+static void raid_set_free(struct raid_set *rs)
 {
 	int i;
 
-	for (i = 0; i < rs->md.raid_disks; i++) {
+	for (i = 0; i < rs->raid_disks; i++) {
 		if (rs->dev[i].meta_dev)
 			dm_put_device(rs->ti, rs->dev[i].meta_dev);
 		md_rdev_clear(&rs->dev[i].rdev);
···
  *    <meta_dev> -
  *
  * This code parses those words.  If there is a failure,
- * the caller must use context_free to unwind the operations.
+ * the caller must use raid_set_free() to unwind the operations.
  */
-static int dev_parms(struct raid_set *rs, char **argv)
+static int parse_dev_params(struct raid_set *rs, struct dm_arg_set *as)
 {
 	int i;
 	int rebuild = 0;
 	int metadata_available = 0;
-	int ret = 0;
+	int r = 0;
+	const char *arg;
 
-	for (i = 0; i < rs->md.raid_disks; i++, argv += 2) {
+	/* Put off the number of raid devices argument to get to dev pairs */
+	arg = dm_shift_arg(as);
+	if (!arg)
+		return -EINVAL;
+
+	for (i = 0; i < rs->raid_disks; i++) {
 		rs->dev[i].rdev.raid_disk = i;
 
 		rs->dev[i].meta_dev = NULL;
···
 		rs->dev[i].rdev.data_offset = 0;
 		rs->dev[i].rdev.mddev = &rs->md;
 
-		if (strcmp(argv[0], "-")) {
-			ret = dm_get_device(rs->ti, argv[0],
-					    dm_table_get_mode(rs->ti->table),
-					    &rs->dev[i].meta_dev);
-			rs->ti->error = "RAID metadata device lookup failure";
-			if (ret)
-				return ret;
+		arg = dm_shift_arg(as);
+		if (!arg)
+			return -EINVAL;
+
+		if (strcmp(arg, "-")) {
+			r = dm_get_device(rs->ti, arg, dm_table_get_mode(rs->ti->table),
+					  &rs->dev[i].meta_dev);
+			if (r) {
+				rs->ti->error = "RAID metadata device lookup failure";
+				return r;
+			}
 
 			rs->dev[i].rdev.sb_page = alloc_page(GFP_KERNEL);
-			if (!rs->dev[i].rdev.sb_page)
+			if (!rs->dev[i].rdev.sb_page) {
+				rs->ti->error = "Failed to allocate superblock page";
 				return -ENOMEM;
+			}
 		}
 
-		if (!strcmp(argv[1], "-")) {
+		arg = dm_shift_arg(as);
+		if (!arg)
+			return -EINVAL;
+
+		if (!strcmp(arg, "-")) {
 			if (!test_bit(In_sync, &rs->dev[i].rdev.flags) &&
 			    (!rs->dev[i].rdev.recovery_offset)) {
 				rs->ti->error = "Drive designated for rebuild not specified";
 				return -EINVAL;
 			}
 
-			rs->ti->error = "No data device supplied with metadata device";
-			if (rs->dev[i].meta_dev)
+			if (rs->dev[i].meta_dev) {
+				rs->ti->error = "No data device supplied with metadata device";
 				return -EINVAL;
+			}
 
 			continue;
 		}
 
-		ret = dm_get_device(rs->ti, argv[1],
-				    dm_table_get_mode(rs->ti->table),
-				    &rs->dev[i].data_dev);
-		if (ret) {
+		r = dm_get_device(rs->ti, arg, dm_table_get_mode(rs->ti->table),
+				  &rs->dev[i].data_dev);
+		if (r) {
 			rs->ti->error = "RAID device lookup failure";
-			return ret;
+			return r;
 		}
 
 		if (rs->dev[i].meta_dev) {
···
 			rs->dev[i].rdev.meta_bdev = rs->dev[i].meta_dev->bdev;
 		}
 		rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev;
-		list_add(&rs->dev[i].rdev.same_set, &rs->md.disks);
+		list_add_tail(&rs->dev[i].rdev.same_set, &rs->md.disks);
 		if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
 			rebuild++;
 	}
···
 		 *
 		 * User could specify 'nosync' option if desperate.
 		 */
-		DMERR("Unable to rebuild drive while array is not in-sync");
-		rs->ti->error = "RAID device lookup failure";
+		rs->ti->error = "Unable to rebuild drive while array is not in-sync";
 		return -EINVAL;
 	}
 
···
 
 	if (!region_size) {
 		/*
-		 * Choose a reasonable default.  All figures in sectors.
+		 * Choose a reasonable default.	 All figures in sectors.
 		 */
 		if (min_region_size > (1 << 13)) {
 			/* If not a power of 2, make it the next power of 2 */
···
 	/*
 	 * Convert sectors to bytes.
 	 */
-	rs->md.bitmap_info.chunksize = (region_size << 9);
+	rs->md.bitmap_info.chunksize = to_bytes(region_size);
 
 	return 0;
 }
···
  */
 static int validate_raid_redundancy(struct raid_set *rs)
 {
-	unsigned i, rebuild_cnt = 0;
-	unsigned rebuilds_per_group = 0, copies, d;
-	unsigned group_size, last_group_start;
+	unsigned int i, rebuild_cnt = 0;
+	unsigned int rebuilds_per_group = 0, copies;
+	unsigned int group_size, last_group_start;
 
 	for (i = 0; i < rs->md.raid_disks; i++)
 		if (!test_bit(In_sync, &rs->dev[i].rdev.flags) ||
···
 			goto too_many;
 		break;
 	case 10:
-		copies = raid10_md_layout_to_copies(rs->md.layout);
+		copies = raid10_md_layout_to_copies(rs->md.new_layout);
 		if (rebuild_cnt < copies)
 			break;
 
···
 		 * simple case where the number of devices is a multiple of the
 		 * number of copies, we must also handle cases where the number
 		 * of devices is not a multiple of the number of copies.
-		 * E.g.    dev1 dev2 dev3 dev4 dev5
-		 *          A    A    B    B    C
-		 *          C    D    D    E    E
+		 * E.g.	   dev1 dev2 dev3 dev4 dev5
+		 *	    A	 A    B	   B	C
+		 *	    C	 D    D	   E	E
 		 */
-		if (!strcmp("near", raid10_md_layout_to_format(rs->md.layout))) {
-			for (i = 0; i < rs->md.raid_disks * copies; i++) {
+		if (__is_raid10_near(rs->md.new_layout)) {
+			for (i = 0; i < rs->md.raid_disks; i++) {
 				if (!(i % copies))
 					rebuilds_per_group = 0;
-				d = i % rs->md.raid_disks;
-				if ((!rs->dev[d].rdev.sb_page ||
-				     !test_bit(In_sync, &rs->dev[d].rdev.flags)) &&
+				if ((!rs->dev[i].rdev.sb_page ||
+				    !test_bit(In_sync, &rs->dev[i].rdev.flags)) &&
 				    (++rebuilds_per_group >= copies))
 					goto too_many;
 			}
···
 		 * use the 'use_far_sets' variant.)
 		 *
 		 * This check is somewhat complicated by the need to account
-		 * for arrays that are not a multiple of (far) copies.  This
+		 * for arrays that are not a multiple of (far) copies.	This
 		 * results in the need to treat the last (potentially larger)
 		 * set differently.
 		 */
···
  *
  * Argument definitions
  *    <chunk_size>			The number of sectors per disk that
- *                                      will form the "stripe"
+ *					will form the "stripe"
  *    [[no]sync]			Force or prevent recovery of the
- *                                      entire array
+ *					entire array
  *    [rebuild <idx>]			Rebuild the drive indicated by the index
  *    [daemon_sleep <ms>]		Time between bitmap daemon work to
- *                                      clear bits
+ *					clear bits
  *    [min_recovery_rate <kB/sec/disk>]	Throttle RAID initialization
  *    [max_recovery_rate <kB/sec/disk>]	Throttle RAID initialization
  *    [write_mostly <idx>]		Indicate a write mostly drive via index
  *    [max_write_behind <sectors>]	See '-write-behind=' (man mdadm)
  *    [stripe_cache <sectors>]		Stripe cache size for higher RAIDs
- *    [region_size <sectors>]           Defines granularity of bitmap
+ *    [region_size <sectors>]		Defines granularity of bitmap
  *
  * RAID10-only options:
- *    [raid10_copies <# copies>]        Number of copies.  (Default: 2)
+ *    [raid10_copies <# copies>]	Number of copies.  (Default: 2)
  *    [raid10_format <near|far|offset>] Layout algorithm.  (Default: near)
  */
-static int parse_raid_params(struct raid_set *rs, char **argv,
-			     unsigned num_raid_params)
+static int parse_raid_params(struct raid_set *rs, struct dm_arg_set *as,
+			     unsigned int num_raid_params)
 {
-	char *raid10_format = "near";
-	unsigned raid10_copies = 2;
-	unsigned i;
-	unsigned long value, region_size = 0;
-	sector_t sectors_per_dev = rs->ti->len;
+	int value, raid10_format = ALGORITHM_RAID10_DEFAULT;
+	unsigned int raid10_copies = 2;
+	unsigned int i, write_mostly = 0;
+	unsigned int region_size = 0;
 	sector_t max_io_len;
-	char *key;
+	const char *arg, *key;
+	struct raid_dev *rd;
+	struct raid_type *rt = rs->raid_type;
+
+	arg = dm_shift_arg(as);
+	num_raid_params--; /* Account for chunk_size argument */
+
+	if (kstrtoint(arg, 10, &value) < 0) {
+		rs->ti->error = "Bad numerical argument given for chunk_size";
+		return -EINVAL;
+	}
 
 	/*
 	 * First, parse the in-order required arguments
 	 * "chunk_size" is the only argument of this type.
 	 */
-	if ((kstrtoul(argv[0], 10, &value) < 0)) {
-		rs->ti->error = "Bad chunk size";
-		return -EINVAL;
-	} else if (rs->raid_type->level == 1) {
+	if (rt_is_raid1(rt)) {
 		if (value)
 			DMERR("Ignoring chunk size parameter for RAID 1");
 		value = 0;
···
 	}
 
 	rs->md.new_chunk_sectors = rs->md.chunk_sectors = value;
-	argv++;
-	num_raid_params--;
 
 	/*
 	 * We set each individual device as In_sync with a completed
···
 	 * replacement then one of the following cases applies:
 	 *
 	 *   1) User specifies 'rebuild'.
-	 *      - Device is reset when param is read.
+	 *	- Device is reset when param is read.
 	 *   2) A new device is supplied.
-	 *      - No matching superblock found, resets device.
+	 *	- No matching superblock found, resets device.
 	 *   3) Device failure was transient and returns on reload.
-	 *      - Failure noticed, resets device for bitmap replay.
+	 *	- Failure noticed, resets device for bitmap replay.
 	 *   4) Device hadn't completed recovery after previous failure.
-	 *      - Superblock is read and overrides recovery_offset.
+	 *	- Superblock is read and overrides recovery_offset.
 	 *
 	 * What is found in the superblocks of the devices is always
 	 * authoritative, unless 'rebuild' or '[no]sync' was specified.
 	 */
-	for (i = 0; i < rs->md.raid_disks; i++) {
+	for (i = 0; i < rs->raid_disks; i++) {
 		set_bit(In_sync, &rs->dev[i].rdev.flags);
 		rs->dev[i].rdev.recovery_offset = MaxSector;
 	}
···
 	 * Second, parse the unordered optional arguments
 	 */
 	for (i = 0; i < num_raid_params; i++) {
-		if (!strcasecmp(argv[i], "nosync")) {
-			rs->md.recovery_cp = MaxSector;
-			rs->ctr_flags |= CTR_FLAG_NOSYNC;
+		key = dm_shift_arg(as);
+		if (!key) {
+			rs->ti->error = "Not enough raid parameters given";
+			return -EINVAL;
+		}
+
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_NOSYNC))) {
+			if (test_and_set_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
+				rs->ti->error = "Only one 'nosync' argument allowed";
+				return -EINVAL;
+			}
 			continue;
 		}
-		if (!strcasecmp(argv[i], "sync")) {
-			rs->md.recovery_cp = 0;
-			rs->ctr_flags |= CTR_FLAG_SYNC;
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_SYNC))) {
+			if (test_and_set_bit(__CTR_FLAG_SYNC, &rs->ctr_flags)) {
+				rs->ti->error = "Only one 'sync' argument allowed";
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_USE_NEAR_SETS))) {
+			if (test_and_set_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags)) {
+				rs->ti->error = "Only one 'raid10_use_new_sets' argument allowed";
+				return -EINVAL;
+			}
 			continue;
 		}
 
-		/* The rest of the optional arguments come in key/value pairs */
-		if ((i + 1) >= num_raid_params) {
+		arg = dm_shift_arg(as);
+		i++; /* Account for the argument pairs */
+		if (!arg) {
 			rs->ti->error = "Wrong number of raid parameters given";
 			return -EINVAL;
 		}
 
-		key = argv[i++];
+		/*
+		 * Parameters that take a string value are checked here.
+		 */
 
-		/* Parameters that take a string value are checked here. */
-		if (!strcasecmp(key, "raid10_format")) {
-			if (rs->raid_type->level != 10) {
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_FORMAT))) {
+			if (test_and_set_bit(__CTR_FLAG_RAID10_FORMAT, &rs->ctr_flags)) {
+				rs->ti->error = "Only one 'raid10_format' argument pair allowed";
+				return -EINVAL;
+			}
+			if (!rt_is_raid10(rt)) {
 				rs->ti->error = "'raid10_format' is an invalid parameter for this RAID type";
 				return -EINVAL;
 			}
-			if (strcmp("near", argv[i]) &&
-			    strcmp("far", argv[i]) &&
-			    strcmp("offset", argv[i])) {
+			raid10_format = raid10_name_to_format(arg);
+			if (raid10_format < 0) {
 				rs->ti->error = "Invalid 'raid10_format' value given";
-				return -EINVAL;
+				return raid10_format;
 			}
-			raid10_format = argv[i];
-			rs->ctr_flags |= CTR_FLAG_RAID10_FORMAT;
 			continue;
 		}
 
-		if (kstrtoul(argv[i], 10, &value) < 0) {
+		if (kstrtoint(arg, 10, &value) < 0) {
 			rs->ti->error = "Bad numerical argument given in raid params";
 			return -EINVAL;
 		}
 
-		/* Parameters that take a numeric value are checked here */
-		if (!strcasecmp(key, "rebuild")) {
-			if (value >= rs->md.raid_disks) {
+		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_REBUILD))) {
+			/*
+			 * "rebuild" is being passed in by userspace to provide
+			 * indexes of replaced devices and to set up additional
+			 * devices on raid level takeover.
+			 */
+			if (!__within_range(value, 0, rs->raid_disks - 1)) {
 				rs->ti->error = "Invalid rebuild index given";
 				return -EINVAL;
 			}
-			clear_bit(In_sync, &rs->dev[value].rdev.flags);
-			rs->dev[value].rdev.recovery_offset = 0;
-			rs->ctr_flags |= CTR_FLAG_REBUILD;
-		} else if (!strcasecmp(key, "write_mostly")) {
-			if (rs->raid_type->level != 1) {
+
+			if (test_and_set_bit(value, (void *) rs->rebuild_disks)) {
+				rs->ti->error = "rebuild for this index already given";
+				return -EINVAL;
+			}
+
+			rd = rs->dev + value;
+			clear_bit(In_sync, &rd->rdev.flags);
+			clear_bit(Faulty, &rd->rdev.flags);
+			rd->rdev.recovery_offset = 0;
+			set_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags);
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_WRITE_MOSTLY))) {
+			if (!rt_is_raid1(rt)) {
 				rs->ti->error = "write_mostly option is only valid for RAID1";
 				return -EINVAL;
 			}
-			if (value >= rs->md.raid_disks) {
-				rs->ti->error = "Invalid write_mostly drive index given";
+
+			if (!__within_range(value, 0, rs->md.raid_disks - 1)) {
+				rs->ti->error = "Invalid write_mostly index given";
 				return -EINVAL;
 			}
+
+			write_mostly++;
 			set_bit(WriteMostly, &rs->dev[value].rdev.flags);
-		} else if (!strcasecmp(key, "max_write_behind")) {
-			if (rs->raid_type->level != 1) {
+			set_bit(__CTR_FLAG_WRITE_MOSTLY, &rs->ctr_flags);
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MAX_WRITE_BEHIND))) {
+			if (!rt_is_raid1(rt)) {
 				rs->ti->error = "max_write_behind option is only valid for RAID1";
 				return -EINVAL;
 			}
-			rs->ctr_flags |= CTR_FLAG_MAX_WRITE_BEHIND;
+
+			if (test_and_set_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags)) {
+				rs->ti->error = "Only one max_write_behind argument pair allowed";
+				return -EINVAL;
+			}
 
 			/*
 			 * In device-mapper, we specify things in sectors, but
···
 				rs->ti->error = "Max write-behind limit out of range";
 				return -EINVAL;
 			}
+
 			rs->md.bitmap_info.max_write_behind = value;
-		} else if (!strcasecmp(key, "daemon_sleep")) {
-			rs->ctr_flags |= CTR_FLAG_DAEMON_SLEEP;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DAEMON_SLEEP))) {
+			if (test_and_set_bit(__CTR_FLAG_DAEMON_SLEEP, &rs->ctr_flags)) {
+				rs->ti->error = "Only one daemon_sleep argument pair allowed";
+				return -EINVAL;
+			}
 			if (!value || (value > MAX_SCHEDULE_TIMEOUT)) {
 				rs->ti->error = "daemon sleep period out of range";
 				return -EINVAL;
 			}
 			rs->md.bitmap_info.daemon_sleep = value;
-		} else if (!strcasecmp(key, "stripe_cache")) {
-			rs->ctr_flags |= CTR_FLAG_STRIPE_CACHE;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DATA_OFFSET))) {
+			/* Userspace passes new data_offset after having extended the the data image LV */
+			if (test_and_set_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
+				rs->ti->error = "Only one data_offset argument pair allowed";
+				return -EINVAL;
+			}
+			/* Ensure sensible data offset */
+			if (value < 0 ||
+			    (value && (value < MIN_FREE_RESHAPE_SPACE || value % to_sector(PAGE_SIZE)))) {
+				rs->ti->error = "Bogus data_offset value";
+				return -EINVAL;
+			}
+			rs->data_offset = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DELTA_DISKS))) {
+			/* Define the +/-# of disks to add to/remove from the given raid set */
+			if (test_and_set_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags)) {
+				rs->ti->error = "Only one delta_disks argument pair allowed";
+				return -EINVAL;
+			}
+			/* Ensure MAX_RAID_DEVICES and raid type minimal_devs! */
+			if (!__within_range(abs(value), 1, MAX_RAID_DEVICES - rt->minimal_devs)) {
+				rs->ti->error = "Too many delta_disk requested";
+				return -EINVAL;
+			}
 
-			/*
-			 * In device-mapper, we specify things in sectors, but
-			 * MD records this value in kB
-			 */
-			value /= 2;
+			rs->delta_disks = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_STRIPE_CACHE))) {
+			if (test_and_set_bit(__CTR_FLAG_STRIPE_CACHE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one stripe_cache argument pair allowed";
+				return -EINVAL;
+			}
 
-			if ((rs->raid_type->level != 5) &&
-			    (rs->raid_type->level != 6)) {
+			if (!rt_is_raid456(rt)) {
 				rs->ti->error = "Inappropriate argument: stripe_cache";
 				return -EINVAL;
 			}
-			if (raid5_set_cache_size(&rs->md, (int)value)) {
-				rs->ti->error = "Bad stripe_cache size";
+
+			rs->stripe_cache_entries = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MIN_RECOVERY_RATE))) {
+			if (test_and_set_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one min_recovery_rate argument pair allowed";
 				return -EINVAL;
 			}
-		} else if (!strcasecmp(key, "min_recovery_rate")) {
-			rs->ctr_flags |= CTR_FLAG_MIN_RECOVERY_RATE;
 			if (value > INT_MAX) {
 				rs->ti->error = "min_recovery_rate out of range";
 				return -EINVAL;
 			}
 			rs->md.sync_speed_min = (int)value;
-		} else if (!strcasecmp(key, "max_recovery_rate")) {
-			rs->ctr_flags |= CTR_FLAG_MAX_RECOVERY_RATE;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MAX_RECOVERY_RATE))) {
+			if (test_and_set_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one max_recovery_rate argument pair allowed";
+				return -EINVAL;
+			}
 			if (value > INT_MAX) {
 				rs->ti->error = "max_recovery_rate out of range";
 				return -EINVAL;
 			}
 			rs->md.sync_speed_max = (int)value;
-		} else if (!strcasecmp(key, "region_size")) {
-			rs->ctr_flags |= CTR_FLAG_REGION_SIZE;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_REGION_SIZE))) {
+			if (test_and_set_bit(__CTR_FLAG_REGION_SIZE, &rs->ctr_flags)) {
+				rs->ti->error = "Only one region_size argument pair allowed";
+				return -EINVAL;
+			}
+
 			region_size = value;
-		} else if (!strcasecmp(key, "raid10_copies") &&
-			   (rs->raid_type->level == 10)) {
-			if ((value < 2) || (value > 0xFF)) {
+			rs->requested_bitmap_chunk_sectors = value;
+		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_COPIES))) {
+			if (test_and_set_bit(__CTR_FLAG_RAID10_COPIES, &rs->ctr_flags)) {
+				rs->ti->error = "Only one raid10_copies argument pair allowed";
+				return -EINVAL;
+			}
+
+			if (!__within_range(value, 2, rs->md.raid_disks)) {
 				rs->ti->error = "Bad value for 'raid10_copies'";
 				return -EINVAL;
 			}
-			rs->ctr_flags |= CTR_FLAG_RAID10_COPIES;
+
 			raid10_copies = value;
 		} else {
 			DMERR("Unable to parse RAID parameter: %s", key);
-			rs->ti->error = "Unable to parse RAID parameters";
+			rs->ti->error = "Unable to parse RAID parameter";
 			return -EINVAL;
 		}
+	}
+
+	if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) &&
+	    test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
+		rs->ti->error = "sync and nosync are mutually exclusive";
+		return -EINVAL;
+	}
+
+	if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags) &&
+	    (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) ||
+	     test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))) {
+		rs->ti->error = "sync/nosync and rebuild are mutually exclusive";
+		return -EINVAL;
+	}
+
+	if (write_mostly >= rs->md.raid_disks) {
+		rs->ti->error = "Can't set all raid1 devices to write_mostly";
+		return -EINVAL;
 	}
 
 	if (validate_region_size(rs, region_size))
···
 	if (dm_set_target_max_io_len(rs->ti, max_io_len))
 		return -EINVAL;
 
-	if (rs->raid_type->level == 10) {
+	if (rt_is_raid10(rt)) {
 		if (raid10_copies > rs->md.raid_disks) {
 			rs->ti->error = "Not enough devices to satisfy specification";
 			return -EINVAL;
 		}
 
-		/*
-		 * If the format is not "near", we only support
-		 * two copies at the moment.
-		 */
-		if (strcmp("near", raid10_format) && (raid10_copies > 2)) {
-			rs->ti->error = "Too many copies for given RAID10 format.";
+		rs->md.new_layout = raid10_format_to_md_layout(rs, raid10_format, raid10_copies);
+		if (rs->md.new_layout < 0) {
+			rs->ti->error = "Error getting raid10 format";
+			return rs->md.new_layout;
+		}
+
+		rt = get_raid_type_by_ll(10, rs->md.new_layout);
+		if (!rt) {
+			rs->ti->error = "Failed to recognize new raid10 layout";
 			return -EINVAL;
 		}
 
-		/* (Len * #mirrors) / #devices */
-		sectors_per_dev = rs->ti->len * raid10_copies;
-		sector_div(sectors_per_dev, rs->md.raid_disks);
-
-		rs->md.layout = raid10_format_to_md_layout(raid10_format,
-							   raid10_copies);
-		rs->md.new_layout = rs->md.layout;
-	} else if ((!rs->raid_type->level || rs->raid_type->level > 1) &&
-		   sector_div(sectors_per_dev,
-			      (rs->md.raid_disks - rs->raid_type->parity_devs))) {
-		rs->ti->error = "Target length not divisible by number of data devices";
-		return -EINVAL;
+		if ((rt->algorithm == ALGORITHM_RAID10_DEFAULT ||
+		     rt->algorithm == ALGORITHM_RAID10_NEAR) &&
+		    test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags)) {
+			rs->ti->error = "RAID10 format 'near' and 'raid10_use_near_sets' are incompatible";
+			return -EINVAL;
+		}
 	}
-	rs->md.dev_sectors = sectors_per_dev;
+
+	rs->raid10_copies = raid10_copies;
 
 	/* Assume there are no metadata devices until the drives are parsed */
 	rs->md.persistent = 0;
 	rs->md.external = 1;
 
+	/* Check, if any invalid ctr arguments have been passed in for the raid level */
+	return rs_check_for_valid_flags(rs);
+}
+
+/* Set raid4/5/6 cache size */
+static int rs_set_raid456_stripe_cache(struct raid_set *rs)
+{
+	int r;
+	struct r5conf *conf;
+	struct mddev *mddev = &rs->md;
+	uint32_t min_stripes = max(mddev->chunk_sectors, mddev->new_chunk_sectors) / 2;
+	uint32_t nr_stripes = rs->stripe_cache_entries;
+
+	if (!rt_is_raid456(rs->raid_type)) {
+		rs->ti->error = "Inappropriate raid level; cannot change stripe_cache size";
+		return -EINVAL;
+	}
+
+	if (nr_stripes < min_stripes) {
+		DMINFO("Adjusting requested %u stripe cache entries to %u to suit stripe size",
+		       nr_stripes, min_stripes);
+		nr_stripes = min_stripes;
+	}
+
+	conf = mddev->private;
+	if (!conf) {
+		rs->ti->error = "Cannot change stripe_cache size on inactive RAID set";
+		return -EINVAL;
+	}
+
+	/* Try setting number of stripes in raid456 stripe cache */
+	if (conf->min_nr_stripes != nr_stripes) {
+		r = raid5_set_cache_size(mddev, nr_stripes);
+		if (r) {
+			rs->ti->error = "Failed to set raid4/5/6 stripe cache size";
+			return r;
+		}
+
+		DMINFO("%u stripe cache entries", nr_stripes);
+	}
+
 	return 0;
+}
+
+/* Return # of data stripes as kept in mddev as of @rs (i.e. as of superblock) */
+static unsigned int mddev_data_stripes(struct raid_set *rs)
+{
+	return rs->md.raid_disks - rs->raid_type->parity_devs;
+}
+
+/* Return # of data stripes of @rs (i.e. as of ctr) */
+static unsigned int rs_data_stripes(struct raid_set *rs)
+{
+	return rs->raid_disks - rs->raid_type->parity_devs;
+}
+
+/* Calculate the sectors per device and per array used for @rs */
+static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
+{
+	int delta_disks;
+	unsigned int data_stripes;
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *rdev;
+	sector_t array_sectors = rs->ti->len, dev_sectors = rs->ti->len;
+
+	if (use_mddev) {
+		delta_disks = mddev->delta_disks;
+		data_stripes = mddev_data_stripes(rs);
+	} else {
+		delta_disks = rs->delta_disks;
+		data_stripes = rs_data_stripes(rs);
+	}
+
+	/* Special raid1 case w/o delta_disks support (yet) */
+	if (rt_is_raid1(rs->raid_type))
+		;
+	else if (rt_is_raid10(rs->raid_type)) {
+		if (rs->raid10_copies < 2 ||
+		    delta_disks < 0) {
+			rs->ti->error = "Bogus raid10 data copies or delta disks";
+			return -EINVAL;
+		}
+
+		dev_sectors *= rs->raid10_copies;
+		if (sector_div(dev_sectors, data_stripes))
+			goto bad;
+
+		array_sectors = (data_stripes + delta_disks) * dev_sectors;
+		if (sector_div(array_sectors, rs->raid10_copies))
+			goto bad;
+
+	} else if (sector_div(dev_sectors, data_stripes))
+		goto bad;
+
+	else
+		/* Striped layouts */
+		array_sectors = (data_stripes + delta_disks) * dev_sectors;
+
+	rdev_for_each(rdev, mddev)
+		rdev->sectors = dev_sectors;
+
+	mddev->array_sectors = array_sectors;
+	mddev->dev_sectors = dev_sectors;
+
+	return 0;
+bad:
+	rs->ti->error = "Target length not divisible by number of data devices";
+	return -EINVAL;
+}
+
+/* Setup recovery on @rs */
+static void __rs_setup_recovery(struct raid_set *rs, sector_t dev_sectors)
+{
+	/* raid0 does not recover */
+	if (rs_is_raid0(rs))
+		rs->md.recovery_cp = MaxSector;
+	/*
+	 * A raid6 set has to be recovered either
+	 * completely or for the grown part to
+	 * ensure proper parity and Q-Syndrome
+	 */
+	else if (rs_is_raid6(rs))
+		rs->md.recovery_cp = dev_sectors;
+	/*
+	 * Other raid set types may skip recovery
+	 * depending on the 'nosync' flag.
+	 */
+	else
+		rs->md.recovery_cp = test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)
+				     ? MaxSector : dev_sectors;
+}
+
+/* Setup recovery on @rs based on raid type, device size and 'nosync' flag */
+static void rs_setup_recovery(struct raid_set *rs, sector_t dev_sectors)
+{
+	if (!dev_sectors)
+		/* New raid set or 'sync' flag provided */
+		__rs_setup_recovery(rs, 0);
+	else if (dev_sectors == MaxSector)
+		/* Prevent recovery */
+		__rs_setup_recovery(rs, MaxSector);
+	else if (rs->dev[0].rdev.sectors < dev_sectors)
+		/* Grown raid set */
+		__rs_setup_recovery(rs, rs->dev[0].rdev.sectors);
+	else
+		__rs_setup_recovery(rs, MaxSector);
 }
 
 static void do_table_event(struct work_struct *ws)
 {
 	struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);
 
+	smp_rmb(); /* Make sure we access most actual mddev properties */
+	if (!rs_is_reshaping(rs))
+		rs_set_capacity(rs);
 	dm_table_event(rs->ti->table);
 }
 
···
 }
 
 /*
+ * Make sure a valid takover (level switch) is being requested on @rs
+ *
+ * Conversions of raid sets from one MD personality to another
+ * have to conform to restrictions which are enforced here.
+ */
+static int rs_check_takeover(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+	unsigned int near_copies;
+
+	if (rs->md.degraded) {
+		rs->ti->error = "Can't takeover degraded raid set";
+		return -EPERM;
+	}
+
+	if (rs_is_reshaping(rs)) {
+		rs->ti->error = "Can't takeover reshaping raid set";
+		return -EPERM;
+	}
+
+	switch (mddev->level) {
+	case 0:
+		/* raid0 -> raid1/5 with one disk */
+		if ((mddev->new_level == 1 || mddev->new_level == 5) &&
+		    mddev->raid_disks == 1)
+			return 0;
+
+		/* raid0 -> raid10 */
+		if (mddev->new_level == 10 &&
+		    !(rs->raid_disks % mddev->raid_disks))
+			return 0;
+
+		/* raid0 with multiple disks -> raid4/5/6 */
+		if (__within_range(mddev->new_level, 4, 6) &&
+		    mddev->new_layout == ALGORITHM_PARITY_N &&
+		    mddev->raid_disks > 1)
+			return 0;
+
+		break;
+
+	case 10:
+		/* Can't takeover raid10_offset! */
+		if (__is_raid10_offset(mddev->layout))
+			break;
+
+		near_copies = __raid10_near_copies(mddev->layout);
+
+		/* raid10* -> raid0 */
+		if (mddev->new_level == 0) {
+			/* Can takeover raid10_near with raid disks divisable by data copies! */
+			if (near_copies > 1 &&
+			    !(mddev->raid_disks % near_copies)) {
+				mddev->raid_disks /= near_copies;
+				mddev->delta_disks = mddev->raid_disks;
+				return 0;
+			}
+
+			/* Can takeover raid10_far */
+			if (near_copies == 1 &&
+			    __raid10_far_copies(mddev->layout) > 1)
+				return 0;
+
+			break;
+		}
+
+		/* raid10_{near,far} -> raid1 */
+		if (mddev->new_level == 1 &&
+		    max(near_copies, __raid10_far_copies(mddev->layout)) == mddev->raid_disks)
+			return 0;
+
+		/* raid10_{near,far} with 2 disks -> raid4/5 */
+		if (__within_range(mddev->new_level, 4, 5) &&
+		    mddev->raid_disks == 2)
+			return 0;
+		break;
+
+	case 1:
+		/* raid1 with 2 disks -> raid4/5 */
+		if (__within_range(mddev->new_level, 4, 5) &&
+		    mddev->raid_disks == 2) {
+			mddev->degraded = 1;
+			return 0;
+		}
+
+		/* raid1 -> raid0 */
+		if (mddev->new_level == 0 &&
+		    mddev->raid_disks == 1)
+			return 0;
+
+		/* raid1 -> raid10 */
+		if (mddev->new_level == 10)
+			return 0;
+		break;
+
+	case 4:
+		/* raid4 -> raid0 */
+		if (mddev->new_level == 0)
+			return 0;
+
+		/* raid4 -> raid1/5 with 2 disks */
+		if ((mddev->new_level == 1 || mddev->new_level == 5) &&
+		    mddev->raid_disks == 2)
+			return 0;
+
+		/* raid4 -> raid5/6 with parity N */
+		if (__within_range(mddev->new_level, 5, 6) &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+		break;
+
+	case 5:
+		/* raid5 with parity N -> raid0 */
+		if (mddev->new_level == 0 &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+
+		/* raid5 with parity N -> raid4 */
+		if (mddev->new_level == 4 &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+
+		/* raid5 with 2 disks -> raid1/4/10 */
+		if ((mddev->new_level == 1 || mddev->new_level == 4 || mddev->new_level == 10) &&
+		    mddev->raid_disks == 2)
+			return 0;
+
+		/* raid5_* ->  raid6_*_6 with Q-Syndrome N (e.g. raid5_ra -> raid6_ra_6 */
+		if (mddev->new_level == 6 &&
+		    ((mddev->layout == ALGORITHM_PARITY_N && mddev->new_layout == ALGORITHM_PARITY_N) ||
+		      __within_range(mddev->new_layout, ALGORITHM_LEFT_ASYMMETRIC_6, ALGORITHM_RIGHT_SYMMETRIC_6)))
+			return 0;
+		break;
+
+	case 6:
+		/* raid6 with parity N -> raid0 */
+		if (mddev->new_level == 0 &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+
+		/* raid6 with parity N -> raid4 */
+		if (mddev->new_level == 4 &&
+		    mddev->layout == ALGORITHM_PARITY_N)
+			return 0;
+
+		/* raid6_*_n with Q-Syndrome N -> raid5_* */
+		if (mddev->new_level == 5 &&
+		    ((mddev->layout == ALGORITHM_PARITY_N && mddev->new_layout == ALGORITHM_PARITY_N) ||
+		     __within_range(mddev->new_layout, ALGORITHM_LEFT_ASYMMETRIC, ALGORITHM_RIGHT_SYMMETRIC)))
+			return 0;
+
+	default:
+		break;
+	}
+
+	rs->ti->error = "takeover not possible";
+	return -EINVAL;
+}
+
+/* True if @rs requested to be taken over */
+static bool rs_takeover_requested(struct raid_set *rs)
+{
+	return rs->md.new_level != rs->md.level;
+}
+
+/* True if @rs is requested to reshape by ctr */
+static bool rs_reshape_requested(struct raid_set *rs)
+{
+	bool change;
+	struct mddev *mddev = &rs->md;
+
+	if (rs_takeover_requested(rs))
+		return false;
+
+	if (!mddev->level)
+		return false;
+
+	change = mddev->new_layout != mddev->layout ||
+		 mddev->new_chunk_sectors != mddev->chunk_sectors ||
+		 rs->delta_disks;
+
+	/* Historical case to support raid1 reshape without delta disks */
+	if (mddev->level == 1) {
+		if (rs->delta_disks)
+			return !!rs->delta_disks;
+
+		return !change &&
+		       mddev->raid_disks != rs->raid_disks;
+	}
+
+	if (mddev->level == 10)
+		return change &&
+		       !__is_raid10_far(mddev->new_layout) &&
+		       rs->delta_disks >= 0;
+
+	return change;
+}
+
+/*  Features */
+#define	FEATURE_FLAG_SUPPORTS_V190	0x1 /* Supports extended superblock */
+
+/* State flags for sb->flags */
+#define	SB_FLAG_RESHAPE_ACTIVE		0x1
+#define	SB_FLAG_RESHAPE_BACKWARDS	0x2
+
+/*
  * This structure is never routinely used by userspace, unlike md superblocks.
  * Devices with this superblock should only ever be accessed via device-mapper.
  */
 #define DM_RAID_MAGIC 0x64526D44
 struct dm_raid_superblock {
 	__le32 magic;		/* "DmRd" */
-	__le32 features;	/* Used to indicate possible future changes */
+	__le32 compat_features;	/* Used to indicate compatible features (like 1.9.0 ondisk metadata extension) */
 
-	__le32 num_devices;	/* Number of devices in this array. (Max 64) */
-	__le32 array_position;	/* The position of this drive in the array */
+	__le32 num_devices;	/* Number of devices in this raid set. (Max 64) */
+	__le32 array_position;	/* The position of this drive in the raid set */
 
 	__le64 events;		/* Incremented by md when superblock updated */
-	__le64 failed_devices;	/* Bit field of devices to indicate failures */
+	__le64 failed_devices;	/* Pre 1.9.0 part of bit field of devices to */
+				/* indicate failures (see extension below) */
 
 	/*
 	 * This offset tracks the progress of the repair or replacement of
···
 	__le64 disk_recovery_offset;
 
 	/*
-	 * This offset tracks the progress of the initial array
+	 * This offset tracks the progress of the initial raid set
 	 * synchronisation/parity calculation.
 	 */
 	__le64 array_resync_offset;
 
 	/*
-	 * RAID characteristics
+	 * raid characteristics
 	 */
 	__le32 level;
 	__le32 layout;
 	__le32 stripe_sectors;
 
-	/* Remainder of a logical block is zero-filled when writing (see super_sync()). */
+	/********************************************************************
+	 * BELOW FOLLOW V1.9.0 EXTENSIONS TO THE PRISTINE SUPERBLOCK FORMAT!!!
+	 *
+	 * FEATURE_FLAG_SUPPORTS_V190 in the features member indicates that those exist
+	 */
+
+	__le32 flags; /* Flags defining array states for reshaping */
+
+	/*
+	 * This offset tracks the progress of a raid
+	 * set reshape in order to be able to restart it
+	 */
+	__le64 reshape_position;
+
+	/*
+	 * These define the properties of the array in case of an interrupted reshape
+	 */
+	__le32 new_level;
+	__le32 new_layout;
+	__le32 new_stripe_sectors;
+	__le32 delta_disks;
+
+	__le64 array_sectors; /* Array size in sectors */
+
+	/*
+	 * Sector offsets to data on devices (reshaping).
+	 * Needed to support out of place reshaping, thus
+	 * not writing over any stripes whilst converting
+	 * them from old to new layout
+	 */
+	__le64 data_offset;
+	__le64 new_data_offset;
+
+	__le64 sectors; /* Used device size in sectors */
+
+	/*
+	 * Additonal Bit field of devices indicating failures to support
+	 * up to 256 devices with the 1.9.0 on-disk metadata format
+	 */
+	__le64 extended_failed_devices[DISKS_ARRAY_ELEMS - 1];
+
+	__le32 incompat_features;	/* Used to indicate any incompatible features */
+
+	/* Always set rest up to logical block size to 0 when writing (see get_metadata_device() below). */
 } __packed;
+
+/*
+ * Check for reshape constraints on raid set @rs:
+ *
+ * - reshape function non-existent
+ * - degraded set
+ * - ongoing recovery
+ * - ongoing reshape
+ *
+ * Returns 0 if none or -EPERM if given constraint
+ * and error message reference in @errmsg
+ */
+static int rs_check_reshape(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+
+	if (!mddev->pers || !mddev->pers->check_reshape)
+		rs->ti->error = "Reshape not supported";
+	else if (mddev->degraded)
+		rs->ti->error = "Can't reshape degraded raid set";
+	else if (rs_is_recovering(rs))
+		rs->ti->error = "Convert request on recovering raid set prohibited";
+	else if (rs_is_reshaping(rs))
+		rs->ti->error = "raid set already reshaping!";
+	else if (!(rs_is_raid1(rs) || rs_is_raid10(rs) || rs_is_raid456(rs)))
+		rs->ti->error = "Reshaping only supported for raid1/4/5/6/10";
+	else
+		return 0;
+
+	return -EPERM;
+}
 
 static int read_disk_sb(struct md_rdev *rdev, int size)
 {
···
 	if (rdev->sb_loaded)
 		return 0;
 
-	if (!sync_page_io(rdev, 0, size, rdev->sb_page, REQ_OP_READ, 0, 1)) {
+	if (!sync_page_io(rdev, 0, size, rdev->sb_page, REQ_OP_READ, 0, true)) {
 		DMERR("Failed to read superblock of device at position %d",
 		      rdev->raid_disk);
 		md_error(rdev->mddev, rdev);
···
 	return 0;
 }
 
+static void sb_retrieve_failed_devices(struct dm_raid_superblock *sb, uint64_t *failed_devices)
+{
+	failed_devices[0] = le64_to_cpu(sb->failed_devices);
+	memset(failed_devices + 1, 0, sizeof(sb->extended_failed_devices));
+
+	if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190) {
+		int i = ARRAY_SIZE(sb->extended_failed_devices);
+
+		while (i--)
+			failed_devices[i+1] = le64_to_cpu(sb->extended_failed_devices[i]);
+	}
+}
+
+static void sb_update_failed_devices(struct dm_raid_superblock *sb, uint64_t *failed_devices)
+{
+	int i = ARRAY_SIZE(sb->extended_failed_devices);
+
+	sb->failed_devices = cpu_to_le64(failed_devices[0]);
+	while (i--)
+		sb->extended_failed_devices[i] = cpu_to_le64(failed_devices[i+1]);
+}
+
+/*
+ * Synchronize the superblock members with the raid set properties
+ *
+ * All superblock data is little endian.
+ */
 static void super_sync(struct mddev *mddev, struct md_rdev *rdev)
 {
-	int i;
-	uint64_t failed_devices;
+	bool update_failed_devices = false;
+	unsigned int i;
+	uint64_t failed_devices[DISKS_ARRAY_ELEMS];
 	struct dm_raid_superblock *sb;
 	struct raid_set *rs = container_of(mddev, struct raid_set, md);
 
+	/* No metadata device, no superblock */
+	if (!rdev->meta_bdev)
+		return;
+
+	BUG_ON(!rdev->sb_page);
+
 	sb = page_address(rdev->sb_page);
-	failed_devices = le64_to_cpu(sb->failed_devices);
 
-	for (i = 0; i < mddev->raid_disks; i++)
-		if (!rs->dev[i].data_dev ||
-		    test_bit(Faulty, &(rs->dev[i].rdev.flags)))
-			failed_devices |= (1ULL << i);
+	sb_retrieve_failed_devices(sb, failed_devices);
 
-	memset(sb + 1, 0, rdev->sb_size - sizeof(*sb));
+	for (i = 0; i < rs->raid_disks; i++)
+		if (!rs->dev[i].data_dev || test_bit(Faulty, &rs->dev[i].rdev.flags)) {
+			update_failed_devices = true;
+			set_bit(i, (void *) failed_devices);
+		}
+
+	if (update_failed_devices)
+		sb_update_failed_devices(sb, failed_devices);
 
 	sb->magic = cpu_to_le32(DM_RAID_MAGIC);
-	sb->features = cpu_to_le32(0);	/* No features yet */
+	sb->compat_features = cpu_to_le32(FEATURE_FLAG_SUPPORTS_V190);
 
 	sb->num_devices = cpu_to_le32(mddev->raid_disks);
 	sb->array_position = cpu_to_le32(rdev->raid_disk);
 
 	sb->events = cpu_to_le64(mddev->events);
-	sb->failed_devices = cpu_to_le64(failed_devices);
 
 	sb->disk_recovery_offset = cpu_to_le64(rdev->recovery_offset);
 	sb->array_resync_offset = cpu_to_le64(mddev->recovery_cp);
···
 	sb->level = cpu_to_le32(mddev->level);
 	sb->layout = cpu_to_le32(mddev->layout);
 	sb->stripe_sectors = cpu_to_le32(mddev->chunk_sectors);
+
+	sb->new_level = cpu_to_le32(mddev->new_level);
+	sb->new_layout = cpu_to_le32(mddev->new_layout);
+	sb->new_stripe_sectors = cpu_to_le32(mddev->new_chunk_sectors);
+
+	sb->delta_disks = cpu_to_le32(mddev->delta_disks);
+
+	smp_rmb(); /* Make sure we access most recent reshape position */
+	sb->reshape_position = cpu_to_le64(mddev->reshape_position);
+	if (le64_to_cpu(sb->reshape_position) != MaxSector) {
+		/* Flag ongoing reshape */
+		sb->flags |= cpu_to_le32(SB_FLAG_RESHAPE_ACTIVE);
+
+		if (mddev->delta_disks < 0 || mddev->reshape_backwards)
+			sb->flags |= cpu_to_le32(SB_FLAG_RESHAPE_BACKWARDS);
+	} else {
+		/* Clear reshape flags */
+		sb->flags &= ~(cpu_to_le32(SB_FLAG_RESHAPE_ACTIVE|SB_FLAG_RESHAPE_BACKWARDS));
+	}
+
+	sb->array_sectors = cpu_to_le64(mddev->array_sectors);
+	sb->data_offset = cpu_to_le64(rdev->data_offset);
+	sb->new_data_offset = cpu_to_le64(rdev->new_data_offset);
+	sb->sectors = cpu_to_le64(rdev->sectors);
+
+	/* Zero out the rest of the payload after the size of the superblock */
+	memset(sb + 1, 0, rdev->sb_size - sizeof(*sb));
 }
 
 /*
···
  */
 static int super_load(struct md_rdev *rdev, struct md_rdev *refdev)
 {
-	int ret;
+	int r;
 	struct dm_raid_superblock *sb;
 	struct dm_raid_superblock *refsb;
 	uint64_t events_sb, events_refsb;
···
 		return -EINVAL;
 	}
 
-	ret = read_disk_sb(rdev, rdev->sb_size);
-	if (ret)
-		return ret;
+	r = read_disk_sb(rdev, rdev->sb_size);
+	if (r)
+		return r;
 
 	sb = page_address(rdev->sb_page);
 
···
 		super_sync(rdev->mddev, rdev);
 
 		set_bit(FirstUse, &rdev->flags);
+		sb->compat_features = cpu_to_le32(FEATURE_FLAG_SUPPORTS_V190);
 
 		/* Force writing of superblocks to disk */
 		set_bit(MD_CHANGE_DEVS, &rdev->mddev->flags);
···
 	return (events_sb > events_refsb) ? 1 : 0;
 }
 
-static int super_init_validation(struct mddev *mddev, struct md_rdev *rdev)
+static int super_init_validation(struct raid_set *rs, struct md_rdev *rdev)
 {
 	int role;
-	struct raid_set *rs = container_of(mddev, struct raid_set, md);
+	unsigned int d;
+	struct mddev *mddev = &rs->md;
 	uint64_t events_sb;
-	uint64_t failed_devices;
+	uint64_t failed_devices[DISKS_ARRAY_ELEMS];
 	struct dm_raid_superblock *sb;
-	uint32_t new_devs = 0;
-	uint32_t rebuilds = 0;
+	uint32_t new_devs = 0, rebuild_and_new = 0, rebuilds = 0;
 	struct md_rdev *r;
 	struct dm_raid_superblock *sb2;
 
 	sb = page_address(rdev->sb_page);
 	events_sb = le64_to_cpu(sb->events);
-	failed_devices = le64_to_cpu(sb->failed_devices);
 
 	/*
 	 * Initialise to 1 if this is a new superblock.
 	 */
 	mddev->events = events_sb ? : 1;
 
+	mddev->reshape_position = MaxSector;
+
 	/*
-	 * Reshaping is not currently allowed
+	 * Reshaping is supported, e.g. reshape_position is valid
+	 * in superblock and superblock content is authoritative.
 	 */
-	if (le32_to_cpu(sb->level) != mddev->level) {
-		DMERR("Reshaping arrays not yet supported. (RAID level change)");
-		return -EINVAL;
-	}
-	if (le32_to_cpu(sb->layout) != mddev->layout) {
-		DMERR("Reshaping arrays not yet supported. (RAID layout change)");
-		DMERR("  0x%X vs 0x%X", le32_to_cpu(sb->layout), mddev->layout);
-		DMERR("  Old layout: %s w/ %d copies",
-		      raid10_md_layout_to_format(le32_to_cpu(sb->layout)),
-		      raid10_md_layout_to_copies(le32_to_cpu(sb->layout)));
-		DMERR("  New layout: %s w/ %d copies",
-		      raid10_md_layout_to_format(mddev->layout),
-		      raid10_md_layout_to_copies(mddev->layout));
-		return -EINVAL;
-	}
-	if (le32_to_cpu(sb->stripe_sectors) != mddev->chunk_sectors) {
-		DMERR("Reshaping arrays not yet supported. (stripe sectors change)");
-		return -EINVAL;
+	if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190) {
+		/* Superblock is authoritative wrt given raid set layout! */
+		mddev->raid_disks = le32_to_cpu(sb->num_devices);
+		mddev->level = le32_to_cpu(sb->level);
+		mddev->layout = le32_to_cpu(sb->layout);
+		mddev->chunk_sectors = le32_to_cpu(sb->stripe_sectors);
+		mddev->new_level = le32_to_cpu(sb->new_level);
+		mddev->new_layout = le32_to_cpu(sb->new_layout);
+		mddev->new_chunk_sectors = le32_to_cpu(sb->new_stripe_sectors);
+		mddev->delta_disks = le32_to_cpu(sb->delta_disks);
+		mddev->array_sectors = le64_to_cpu(sb->array_sectors);
+
+		/* raid was reshaping and got interrupted */
+		if (le32_to_cpu(sb->flags) & SB_FLAG_RESHAPE_ACTIVE) {
+			if (test_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags)) {
+				DMERR("Reshape requested but raid set is still reshaping");
+				return -EINVAL;
+			}
+
+			if (mddev->delta_disks < 0 ||
+			    (!mddev->delta_disks && (le32_to_cpu(sb->flags) & SB_FLAG_RESHAPE_BACKWARDS)))
+				mddev->reshape_backwards = 1;
+			else
+				mddev->reshape_backwards = 0;
+
+			mddev->reshape_position = le64_to_cpu(sb->reshape_position);
+			rs->raid_type = get_raid_type_by_ll(mddev->level, mddev->layout);
+		}
+
+	} else {
+		/*
+		 * No takeover/reshaping, because we don't have the extended v1.9.0 metadata
+		 */
+		if (le32_to_cpu(sb->level) != mddev->level) {
+			DMERR("Reshaping/takeover raid sets not yet supported. (raid level/stripes/size change)");
+			return -EINVAL;
+		}
+		if (le32_to_cpu(sb->layout) != mddev->layout) {
+			DMERR("Reshaping raid sets not yet supported. (raid layout change)");
+			DMERR("	 0x%X vs 0x%X", le32_to_cpu(sb->layout), mddev->layout);
+			DMERR("	 Old layout: %s w/ %d copies",
+			      raid10_md_layout_to_format(le32_to_cpu(sb->layout)),
+			      raid10_md_layout_to_copies(le32_to_cpu(sb->layout)));
+			DMERR("	 New layout: %s w/ %d copies",
+			      raid10_md_layout_to_format(mddev->layout),
+			      raid10_md_layout_to_copies(mddev->layout));
+			return -EINVAL;
+		}
+		if (le32_to_cpu(sb->stripe_sectors) != mddev->chunk_sectors) {
+			DMERR("Reshaping raid sets not yet supported. (stripe sectors change)");
+			return -EINVAL;
+		}
+
+		/* We can only change the number of devices in raid1 with old (i.e. pre 1.0.7) metadata */
+		if (!rt_is_raid1(rs->raid_type) &&
+		    (le32_to_cpu(sb->num_devices) != mddev->raid_disks)) {
+			DMERR("Reshaping raid sets not yet supported. (device count change from %u to %u)",
+			      sb->num_devices, mddev->raid_disks);
+			return -EINVAL;
+		}
+
+		/* Table line is checked vs. authoritative superblock */
+		rs_set_new(rs);
 	}
 
-	/* We can only change the number of devices in RAID1 right now */
-	if ((rs->raid_type->level != 1) &&
-	    (le32_to_cpu(sb->num_devices) != mddev->raid_disks)) {
-		DMERR("Reshaping arrays not yet supported. (device count change)");
-		return -EINVAL;
-	}
-
-	if (!(rs->ctr_flags & (CTR_FLAG_SYNC | CTR_FLAG_NOSYNC)))
+	if (!test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))
 		mddev->recovery_cp = le64_to_cpu(sb->array_resync_offset);
 
 	/*
 	 * During load, we set FirstUse if a new superblock was written.
 	 * There are two reasons we might not have a superblock:
-	 * 1) The array is brand new - in which case, all of the
-	 *    devices must have their In_sync bit set.  Also,
+	 * 1) The raid set is brand new - in which case, all of the
+	 *    devices must have their In_sync bit set.	Also,
 	 *    recovery_cp must be 0, unless forced.
-	 * 2) This is a new device being added to an old array
+	 * 2) This is a new device being added to an old raid set
 	 *    and the new device needs to be rebuilt - in which
 	 *    case the In_sync bit will /not/ be set and
 	 *    recovery_cp must be MaxSector.
+	 * 3) This is/are a new device(s) being added to an old
+	 *    raid set during takeover to a higher raid level
+	 *    to provide capacity for redundancy or during reshape
+	 *    to add capacity to grow the raid set.
 	 */
+	d = 0;
 	rdev_for_each(r, mddev) {
-		if (!test_bit(In_sync, &r->flags)) {
-			DMINFO("Device %d specified for rebuild: "
-			       "Clearing superblock", r->raid_disk);
-			rebuilds++;
-		} else if (test_bit(FirstUse, &r->flags))
+		if (test_bit(FirstUse, &r->flags))
 			new_devs++;
+
+		if (!test_bit(In_sync, &r->flags)) {
+			DMINFO("Device %d specified for rebuild; clearing superblock",
+				r->raid_disk);
+			rebuilds++;
+
+			if (test_bit(FirstUse, &r->flags))
+				rebuild_and_new++;
+		}
+
+		d++;
 	}
 
-	if (!rebuilds) {
-		if (new_devs == mddev->raid_disks) {
-			DMINFO("Superblocks created for new array");
+	if (new_devs == rs->raid_disks || !rebuilds) {
+		/* Replace a broken device */
+		if (new_devs == 1 && !rs->delta_disks)
+			;
+		if (new_devs == rs->raid_disks) {
+			DMINFO("Superblocks created for new raid set");
 			set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
-		} else if (new_devs) {
-			DMERR("New device injected "
-			      "into existing array without 'rebuild' "
-			      "parameter specified");
+		} else if (new_devs != rebuilds &&
+			   new_devs != rs->delta_disks) {
+			DMERR("New device injected into existing raid set without "
+			      "'delta_disks' or 'rebuild' parameter specified");
 			return -EINVAL;
 		}
-	} else if (new_devs) {
-		DMERR("'rebuild' devices cannot be "
-		      "injected into an array with other first-time devices");
+	} else if (new_devs && new_devs != rebuilds) {
+		DMERR("%u 'rebuild' devices cannot be injected into"
+		      " a raid set with %u other first-time devices",
+		      rebuilds, new_devs);
 		return -EINVAL;
-	} else if (mddev->recovery_cp != MaxSector) {
-		DMERR("'rebuild' specified while array is not in-sync");
-		return -EINVAL;
+	} else if (rebuilds) {
+		if (rebuild_and_new && rebuilds != rebuild_and_new) {
+			DMERR("new device%s provided without 'rebuild'",
+			      new_devs > 1 ? "s" : "");
+			return -EINVAL;
+		} else if (rs_is_recovering(rs)) {
+			DMERR("'rebuild' specified while raid set is not in-sync (recovery_cp=%llu)",
+			      (unsigned long long) mddev->recovery_cp);
+			return -EINVAL;
+		} else if (rs_is_reshaping(rs)) {
+			DMERR("'rebuild' specified while raid set is being reshaped (reshape_position=%llu)",
+			      (unsigned long long) mddev->reshape_position);
+			return -EINVAL;
+		}
 	}
 
 	/*
 	 * Now we set the Faulty bit for those devices that are
 	 * recorded in the superblock as failed.
 	 */
+	sb_retrieve_failed_devices(sb, failed_devices);
 	rdev_for_each(r, mddev) {
 		if (!r->sb_page)
 			continue;
 		sb2 = page_address(r->sb_page);
 		sb2->failed_devices = 0;
+		memset(sb2->extended_failed_devices, 0, sizeof(sb2->extended_failed_devices));
 
 		/*
 		 * Check for any device re-ordering.
 		 */
 		if (!test_bit(FirstUse, &r->flags) && (r->raid_disk >= 0)) {
 			role = le32_to_cpu(sb2->array_position);
+			if (role < 0)
+				continue;
+
 			if (role != r->raid_disk) {
-				if (rs->raid_type->level != 1) {
-					rs->ti->error = "Cannot change device "
-						"positions in RAID array";
+				if (__is_raid10_near(mddev->layout)) {
+					if (mddev->raid_disks % __raid10_near_copies(mddev->layout) ||
+					    rs->raid_disks % rs->raid10_copies) {
+						rs->ti->error =
+							"Cannot change raid10 near set to odd # of devices!";
+						return -EINVAL;
+					}
+
+					sb2->array_position = cpu_to_le32(r->raid_disk);
+
+				} else if (!(rs_is_raid10(rs) && rt_is_raid0(rs->raid_type)) &&
+					   !(rs_is_raid0(rs) && rt_is_raid10(rs->raid_type)) &&
+					   !rt_is_raid1(rs->raid_type)) {
+					rs->ti->error = "Cannot change device positions in raid set";
 					return -EINVAL;
 				}
-				DMINFO("RAID1 device #%d now at position #%d",
-				       role, r->raid_disk);
+
+				DMINFO("raid device #%d now at position #%d", role, r->raid_disk);
 			}
 
 			/*
 			 * Partial recovery is performed on
 			 * returning failed devices.
 			 */
-			if (failed_devices & (1 << role))
+			if (test_bit(role, (void *) failed_devices))
 				set_bit(Faulty, &r->flags);
 		}
 	}
···
 static int super_validate(struct raid_set *rs, struct md_rdev *rdev)
 {
 	struct mddev *mddev = &rs->md;
-	struct dm_raid_superblock *sb = page_address(rdev->sb_page);
+	struct dm_raid_superblock *sb;
+
+	if (rs_is_raid0(rs) || !rdev->sb_page)
+		return 0;
+
+	sb = page_address(rdev->sb_page);
 
 	/*
 	 * If mddev->events is not set, we know we have not yet initialized
 	 * the array.
 	 */
-	if (!mddev->events && super_init_validation(mddev, rdev))
+	if (!mddev->events && super_init_validation(rs, rdev))
 		return -EINVAL;
 
-	if (le32_to_cpu(sb->features)) {
-		rs->ti->error = "Unable to assemble array: No feature flags supported yet";
+	if (le32_to_cpu(sb->compat_features) != FEATURE_FLAG_SUPPORTS_V190) {
+		rs->ti->error = "Unable to assemble array: Unknown flag(s) in compatible feature flags";
+		return -EINVAL;
+	}
+
+	if (sb->incompat_features) {
+		rs->ti->error = "Unable to assemble array: No incompatible feature flags supported yet";
 		return -EINVAL;
 	}
 
 	/* Enable bitmap creation for RAID levels != 0 */
-	mddev->bitmap_info.offset = (rs->raid_type->level) ? to_sector(4096) : 0;
+	mddev->bitmap_info.offset = rt_is_raid0(rs->raid_type) ? 0 : to_sector(4096);
 	rdev->mddev->bitmap_info.default_offset = mddev->bitmap_info.offset;
 
-	if (!test_bit(FirstUse, &rdev->flags)) {
+	if (!test_and_clear_bit(FirstUse, &rdev->flags)) {
+		/* Retrieve device size stored in superblock to be prepared for shrink */
+		rdev->sectors = le64_to_cpu(sb->sectors);
 		rdev->recovery_offset = le64_to_cpu(sb->disk_recovery_offset);
-		if (rdev->recovery_offset != MaxSector)
-			clear_bit(In_sync, &rdev->flags);
+		if (rdev->recovery_offset == MaxSector)
+			set_bit(In_sync, &rdev->flags);
+		/*
+		 * If no reshape in progress -> we're recovering single
+		 * disk(s) and have to set the device(s) to out-of-sync
+		 */
+		else if (!rs_is_reshaping(rs))
+			clear_bit(In_sync, &rdev->flags); /* Mandatory for recovery */
 	}
 
 	/*
 	 * If a device comes back, set it as not In_sync and no longer faulty.
 	 */
-	if (test_bit(Faulty, &rdev->flags)) {
-		clear_bit(Faulty, &rdev->flags);
+	if (test_and_clear_bit(Faulty, &rdev->flags)) {
+		rdev->recovery_offset = 0;
 		clear_bit(In_sync, &rdev->flags);
 		rdev->saved_raid_disk = rdev->raid_disk;
-		rdev->recovery_offset = 0;
 	}
 
-	clear_bit(FirstUse, &rdev->flags);
+	/* Reshape support -> restore repective data offsets */
+	rdev->data_offset = le64_to_cpu(sb->data_offset);
+	rdev->new_data_offset = le64_to_cpu(sb->new_data_offset);
 
 	return 0;
 }
···
  */
 static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
 {
-	int ret;
+	int r;
 	struct raid_dev *dev;
 	struct md_rdev *rdev, *tmp, *freshest;
 	struct mddev *mddev = &rs->md;
···
 		/*
 		 * Skipping super_load due to CTR_FLAG_SYNC will cause
 		 * the array to undergo initialization again as
-		 * though it were new.  This is the intended effect
+		 * though it were new.	This is the intended effect
 		 * of the "sync" directive.
 		 *
 		 * When reshaping capability is added, we must ensure
 		 * that the "sync" directive is disallowed during the
 		 * reshape.
 		 */
-		rdev->sectors = to_sector(i_size_read(rdev->bdev->bd_inode));
-
-		if (rs->ctr_flags & CTR_FLAG_SYNC)
+		if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags))
 			continue;
 
 		if (!rdev->meta_bdev)
 			continue;
 
-		ret = super_load(rdev, freshest);
+		r = super_load(rdev, freshest);
 
-		switch (ret) {
+		switch (r) {
 		case 1:
 			freshest = rdev;
 			break;
···
 	 * Validation of the freshest device provides the source of
 	 * validation for the remaining devices.
 	 */
-	ti->error = "Unable to assemble array: Invalid superblocks";
+	rs->ti->error = "Unable to assemble array: Invalid superblocks";
 	if (super_validate(rs, freshest))
 		return -EINVAL;
 
 	rdev_for_each(rdev, mddev)
 		if ((rdev != freshest) && super_validate(rs, rdev))
 			return -EINVAL;
+	return 0;
+}
+
+/*
+ * Adjust data_offset and new_data_offset on all disk members of @rs
+ * for out of place reshaping if requested by contructor
+ *
+ * We need free space at the beginning of each raid disk for forward
+ * and at the end for backward reshapes which userspace has to provide
+ * via remapping/reordering of space.
+ */
+static int rs_adjust_data_offsets(struct raid_set *rs)
+{
+	sector_t data_offset = 0, new_data_offset = 0;
+	struct md_rdev *rdev;
+
+	/* Constructor did not request data offset change */
+	if (!test_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
+		if (!rs_is_reshapable(rs))
+			goto out;
+
+		return 0;
+	}
+
+	/* HM FIXME: get InSync raid_dev? */
+	rdev = &rs->dev[0].rdev;
+
+	if (rs->delta_disks < 0) {
+		/*
+		 * Removing disks (reshaping backwards):
+		 *
+		 * - before reshape: data is at offset 0 and free space
+		 *		     is at end of each component LV
+		 *
+		 * - after reshape: data is at offset rs->data_offset != 0 on each component LV
+		 */
+		data_offset = 0;
+		new_data_offset = rs->data_offset;
+
+	} else if (rs->delta_disks > 0) {
+		/*
+		 * Adding disks (reshaping forwards):
+		 *
+		 * - before reshape: data is at offset rs->data_offset != 0 and
+		 *		     free space is at begin of each component LV
+		 *
+		 * - after reshape: data is at offset 0 on each component LV
+		 */
+		data_offset = rs->data_offset;
+		new_data_offset = 0;
+
+	} else {
+		/*
+		 * User space passes in 0 for data offset after having removed reshape space
+		 *
+		 * - or - (data offset != 0)
+		 *
+		 * Changing RAID layout or chunk size -> toggle offsets
+		 *
+		 * - before reshape: data is at offset rs->data_offset 0 and
+		 *		     free space is at end of each component LV
+		 *		     -or-
+		 *                   data is at offset rs->data_offset != 0 and
+		 *		     free space is at begin of each component LV
+		 *
+		 * - after reshape: data is at offset 0 if it was at offset != 0
+		 *                  or at offset != 0 if it was at offset 0
+		 *                  on each component LV
+		 *
+		 */
+		data_offset = rs->data_offset ? rdev->data_offset : 0;
+		new_data_offset = data_offset ? 0 : rs->data_offset;
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+	}
+
+	/*
+	 * Make sure we got a minimum amount of free sectors per device
+	 */
+	if (rs->data_offset &&
+	    to_sector(i_size_read(rdev->bdev->bd_inode)) - rdev->sectors < MIN_FREE_RESHAPE_SPACE) {
+		rs->ti->error = data_offset ? "No space for forward reshape" :
+					      "No space for backward reshape";
+		return -ENOSPC;
+	}
+out:
+	/* Adjust data offsets on all rdevs */
+	rdev_for_each(rdev, &rs->md) {
+		rdev->data_offset = data_offset;
+		rdev->new_data_offset = new_data_offset;
+	}
 
 	return 0;
+}
+
+/* Userpace reordered disks -> adjust raid_disk indexes in @rs */
+static void __reorder_raid_disk_indexes(struct raid_set *rs)
+{
+	int i = 0;
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, &rs->md) {
+		rdev->raid_disk = i++;
+		rdev->saved_raid_disk = rdev->new_raid_disk = -1;
+	}
+}
+
+/*
+ * Setup @rs for takeover by a different raid level
+ */
+static int rs_setup_takeover(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *rdev;
+	unsigned int d = mddev->raid_disks = rs->raid_disks;
+	sector_t new_data_offset = rs->dev[0].rdev.data_offset ? 0 : rs->data_offset;
+
+	if (rt_is_raid10(rs->raid_type)) {
+		if (mddev->level == 0) {
+			/* Userpace reordered disks -> adjust raid_disk indexes */
+			__reorder_raid_disk_indexes(rs);
+
+			/* raid0 -> raid10_far layout */
+			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_FAR,
+								   rs->raid10_copies);
+		} else if (mddev->level == 1)
+			/* raid1 -> raid10_near layout */
+			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
+								   rs->raid_disks);
+		else
+			return -EINVAL;
+
+	}
+
+	clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
+	mddev->recovery_cp = MaxSector;
+
+	while (d--) {
+		rdev = &rs->dev[d].rdev;
+
+		if (test_bit(d, (void *) rs->rebuild_disks)) {
+			clear_bit(In_sync, &rdev->flags);
+			clear_bit(Faulty, &rdev->flags);
+			mddev->recovery_cp = rdev->recovery_offset = 0;
+			/* Bitmap has to be created when we do an "up" takeover */
+			set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
+		}
+
+		rdev->new_data_offset = new_data_offset;
+	}
+
+	return 0;
+}
+
+/* Prepare @rs for reshape */
+static int rs_prepare_reshape(struct raid_set *rs)
+{
+	bool reshape;
+	struct mddev *mddev = &rs->md;
+
+	if (rs_is_raid10(rs)) {
+		if (rs->raid_disks != mddev->raid_disks &&
+		    __is_raid10_near(mddev->layout) &&
+		    rs->raid10_copies &&
+		    rs->raid10_copies != __raid10_near_copies(mddev->layout)) {
+			/*
+			 * raid disk have to be multiple of data copies to allow this conversion,
+			 *
+			 * This is actually not a reshape it is a
+			 * rebuild of any additional mirrors per group
+			 */
+			if (rs->raid_disks % rs->raid10_copies) {
+				rs->ti->error = "Can't reshape raid10 mirror groups";
+				return -EINVAL;
+			}
+
+			/* Userpace reordered disks to add/remove mirrors -> adjust raid_disk indexes */
+			__reorder_raid_disk_indexes(rs);
+			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
+								   rs->raid10_copies);
+			mddev->new_layout = mddev->layout;
+			reshape = false;
+		} else
+			reshape = true;
+
+	} else if (rs_is_raid456(rs))
+		reshape = true;
+
+	else if (rs_is_raid1(rs)) {
+		if (rs->delta_disks) {
+			/* Process raid1 via delta_disks */
+			mddev->degraded = rs->delta_disks < 0 ? -rs->delta_disks : rs->delta_disks;
+			reshape = true;
+		} else {
+			/* Process raid1 without delta_disks */
+			mddev->raid_disks = rs->raid_disks;
+			set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
+			reshape = false;
+		}
+	} else {
+		rs->ti->error = "Called with bogus raid type";
+		return -EINVAL;
+	}
+
+	if (reshape) {
+		set_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags);
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+		set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
+	} else if (mddev->raid_disks < rs->raid_disks)
+		/* Create new superblocks and bitmaps, if any new disks */
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+
+	return 0;
+}
+
+/*
+ *
+ * - change raid layout
+ * - change chunk size
+ * - add disks
+ * - remove disks
+ */
+static int rs_setup_reshape(struct raid_set *rs)
+{
+	int r = 0;
+	unsigned int cur_raid_devs, d;
+	struct mddev *mddev = &rs->md;
+	struct md_rdev *rdev;
+
+	mddev->delta_disks = rs->delta_disks;
+	cur_raid_devs = mddev->raid_disks;
+
+	/* Ignore impossible layout change whilst adding/removing disks */
+	if (mddev->delta_disks &&
+	    mddev->layout != mddev->new_layout) {
+		DMINFO("Ignoring invalid layout change with delta_disks=%d", rs->delta_disks);
+		mddev->new_layout = mddev->layout;
+	}
+
+	/*
+	 * Adjust array size:
+	 *
+	 * - in case of adding disks, array size has
+	 *   to grow after the disk adding reshape,
+	 *   which'll hapen in the event handler;
+	 *   reshape will happen forward, so space has to
+	 *   be available at the beginning of each disk
+	 *
+	 * - in case of removing disks, array size
+	 *   has to shrink before starting the reshape,
+	 *   which'll happen here;
+	 *   reshape will happen backward, so space has to
+	 *   be available at the end of each disk
+	 *
+	 * - data_offset and new_data_offset are
+	 *   adjusted for aforementioned out of place
+	 *   reshaping based on userspace passing in
+	 *   the "data_offset <sectors>" key/value
+	 *   pair via the constructor
+	 */
+
+	/* Add disk(s) */
+	if (rs->delta_disks > 0) {
+		/* Prepare disks for check in raid4/5/6/10 {check|start}_reshape */
+		for (d = cur_raid_devs; d < rs->raid_disks; d++) {
+			rdev = &rs->dev[d].rdev;
+			clear_bit(In_sync, &rdev->flags);
+
+			/*
+			 * save_raid_disk needs to be -1, or recovery_offset will be set to 0
+			 * by md, which'll store that erroneously in the superblock on reshape
+			 */
+			rdev->saved_raid_disk = -1;
+			rdev->raid_disk = d;
+
+			rdev->sectors = mddev->dev_sectors;
+			rdev->recovery_offset = rs_is_raid1(rs) ? 0 : MaxSector;
+		}
+
+		mddev->reshape_backwards = 0; /* adding disks -> forward reshape */
+
+	/* Remove disk(s) */
+	} else if (rs->delta_disks < 0) {
+		r = rs_set_dev_and_array_sectors(rs, true);
+		mddev->reshape_backwards = 1; /* removing disk(s) -> backward reshape */
+
+	/* Change layout and/or chunk size */
+	} else {
+		/*
+		 * Reshape layout (e.g. raid5_ls -> raid5_n) and/or chunk size:
+		 *
+		 * keeping number of disks and do layout change ->
+		 *
+		 * toggle reshape_backward depending on data_offset:
+		 *
+		 * - free space upfront -> reshape forward
+		 *
+		 * - free space at the end -> reshape backward
+		 *
+		 *
+		 * This utilizes free reshape space avoiding the need
+		 * for userspace to move (parts of) LV segments in
+		 * case of layout/chunksize change  (for disk
+		 * adding/removing reshape space has to be at
+		 * the proper address (see above with delta_disks):
+		 *
+		 * add disk(s)   -> begin
+		 * remove disk(s)-> end
+		 */
+		mddev->reshape_backwards = rs->dev[0].rdev.data_offset ? 0 : 1;
+	}
+
+	return r;
 }
 
 /*
  * Enable/disable discard support on RAID set depending on
  * RAID level and discard properties of underlying RAID members.
  */
-static void configure_discard_support(struct dm_target *ti, struct raid_set *rs)
+static void configure_discard_support(struct raid_set *rs)
 {
 	int i;
 	bool raid456;
+	struct dm_target *ti = rs->ti;
 
 	/* Assume discards not supported until after checks below. */
 	ti->discards_supported = false;
···
 	/* RAID level 4,5,6 require discard_zeroes_data for data integrity! */
 	raid456 = (rs->md.level == 4 || rs->md.level == 5 || rs->md.level == 6);
 
-	for (i = 0; i < rs->md.raid_disks; i++) {
+	for (i = 0; i < rs->raid_disks; i++) {
 		struct request_queue *q;
 
 		if (!rs->dev[i].rdev.bdev)
···
 }
 
 /*
- * Construct a RAID4/5/6 mapping:
+ * Construct a RAID0/1/10/4/5/6 mapping:
  * Args:
- *	<raid_type> <#raid_params> <raid_params>		\
- *	<#raid_devs> { <meta_dev1> <dev1> .. <meta_devN> <devN> }
+ *	<raid_type> <#raid_params> <raid_params>{0,}	\
+ *	<#raid_devs> [<meta_dev1> <dev1>]{1,}
  *
- * <raid_params> varies by <raid_type>.  See 'parse_raid_params' for
+ * <raid_params> varies by <raid_type>.	 See 'parse_raid_params' for
  * details on possible <raid_params>.
+ *
+ * Userspace is free to initialize the metadata devices, hence the superblocks to
+ * enforce recreation based on the passed in table parameters.
+ *
  */
-static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
+static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
-	int ret;
+	int r;
+	bool resize;
 	struct raid_type *rt;
-	unsigned long num_raid_params, num_raid_devs;
+	unsigned int num_raid_params, num_raid_devs;
+	sector_t calculated_dev_sectors;
 	struct raid_set *rs = NULL;
+	const char *arg;
+	struct rs_layout rs_layout;
+	struct dm_arg_set as = { argc, argv }, as_nrd;
+	struct dm_arg _args[] = {
+		{ 0, as.argc, "Cannot understand number of raid parameters" },
+		{ 1, 254, "Cannot understand number of raid devices parameters" }
+	};
 
-	/* Must have at least <raid_type> <#raid_params> */
-	if (argc < 2) {
-		ti->error = "Too few arguments";
+	/* Must have <raid_type> */
+	arg = dm_shift_arg(&as);
+	if (!arg) {
+		ti->error = "No arguments";
 		return -EINVAL;
 	}
 
-	/* raid type */
-	rt = get_raid_type(argv[0]);
+	rt = get_raid_type(arg);
 	if (!rt) {
 		ti->error = "Unrecognised raid_type";
 		return -EINVAL;
 	}
-	argc--;
-	argv++;
 
-	/* number of RAID parameters */
-	if (kstrtoul(argv[0], 10, &num_raid_params) < 0) {
-		ti->error = "Cannot understand number of RAID parameters";
+	/* Must have <#raid_params> */
+	if (dm_read_arg_group(_args, &as, &num_raid_params, &ti->error))
 		return -EINVAL;
-	}
-	argc--;
-	argv++;
 
-	/* Skip over RAID params for now and find out # of devices */
-	if (num_raid_params >= argc) {
-		ti->error = "Arguments do not agree with counts given";
+	/* number of raid device tupples <meta_dev data_dev> */
+	as_nrd = as;
+	dm_consume_args(&as_nrd, num_raid_params);
+	_args[1].max = (as_nrd.argc - 1) / 2;
+	if (dm_read_arg(_args + 1, &as_nrd, &num_raid_devs, &ti->error))
 		return -EINVAL;
-	}
 
-	if ((kstrtoul(argv[num_raid_params], 10, &num_raid_devs) < 0) ||
-	    (num_raid_devs > MAX_RAID_DEVICES)) {
-		ti->error = "Cannot understand number of raid devices";
+	if (!__within_range(num_raid_devs, 1, MAX_RAID_DEVICES)) {
+		ti->error = "Invalid number of supplied raid devices";
 		return -EINVAL;
 	}
 
-	argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */
-	if (argc != (num_raid_devs * 2)) {
-		ti->error = "Supplied RAID devices does not match the count given";
-		return -EINVAL;
-	}
-
-	rs = context_alloc(ti, rt, (unsigned)num_raid_devs);
+	rs = raid_set_alloc(ti, rt, num_raid_devs);
 	if (IS_ERR(rs))
 		return PTR_ERR(rs);
 
-	ret = parse_raid_params(rs, argv, (unsigned)num_raid_params);
-	if (ret)
+	r = parse_raid_params(rs, &as, num_raid_params);
+	if (r)
 		goto bad;
 
-	argv += num_raid_params + 1;
-
-	ret = dev_parms(rs, argv);
-	if (ret)
+	r = parse_dev_params(rs, &as);
+	if (r)
 		goto bad;
 
 	rs->md.sync_super = super_sync;
-	ret = analyse_superblocks(ti, rs);
-	if (ret)
+
+	/*
+	 * Calculate ctr requested array and device sizes to allow
+	 * for superblock analysis needing device sizes defined.
+	 *
+	 * Any existing superblock will overwrite the array and device sizes
+	 */
+	r = rs_set_dev_and_array_sectors(rs, false);
+	if (r)
 		goto bad;
+
+	calculated_dev_sectors = rs->dev[0].rdev.sectors;
+
+	/*
+	 * Backup any new raid set level, layout, ...
+	 * requested to be able to compare to superblock
+	 * members for conversion decisions.
+	 */
+	rs_config_backup(rs, &rs_layout);
+
+	r = analyse_superblocks(ti, rs);
+	if (r)
+		goto bad;
+
+	resize = calculated_dev_sectors != rs->dev[0].rdev.sectors;
 
 	INIT_WORK(&rs->md.event_work, do_table_event);
 	ti->private = rs;
 	ti->num_flush_bios = 1;
 
+	/* Restore any requested new layout for conversion decision */
+	rs_config_restore(rs, &rs_layout);
+
 	/*
-	 * Disable/enable discard support on RAID set.
+	 * Now that we have any superblock metadata available,
+	 * check for new, recovering, reshaping, to be taken over,
+	 * to be reshaped or an existing, unchanged raid set to
+	 * run in sequence.
 	 */
-	configure_discard_support(ti, rs);
+	if (test_bit(MD_ARRAY_FIRST_USE, &rs->md.flags)) {
+		/* A new raid6 set has to be recovered to ensure proper parity and Q-Syndrome */
+		if (rs_is_raid6(rs) &&
+		    test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
+			ti->error = "'nosync' not allowed for new raid6 set";
+			r = -EINVAL;
+			goto bad;
+		}
+		rs_setup_recovery(rs, 0);
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+		rs_set_new(rs);
+	} else if (rs_is_recovering(rs)) {
+		/* A recovering raid set may be resized */
+		; /* skip setup rs */
+	} else if (rs_is_reshaping(rs)) {
+		/* Have to reject size change request during reshape */
+		if (resize) {
+			ti->error = "Can't resize a reshaping raid set";
+			r = -EPERM;
+			goto bad;
+		}
+		/* skip setup rs */
+	} else if (rs_takeover_requested(rs)) {
+		if (rs_is_reshaping(rs)) {
+			ti->error = "Can't takeover a reshaping raid set";
+			r = -EPERM;
+			goto bad;
+		}
+
+		/*
+		 * If a takeover is needed, userspace sets any additional
+		 * devices to rebuild and we can check for a valid request here.
+		 *
+		 * If acceptible, set the level to the new requested
+		 * one, prohibit requesting recovery, allow the raid
+		 * set to run and store superblocks during resume.
+		 */
+		r = rs_check_takeover(rs);
+		if (r)
+			goto bad;
+
+		r = rs_setup_takeover(rs);
+		if (r)
+			goto bad;
+
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+		set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
+		/* Takeover ain't recovery, so disable recovery */
+		rs_setup_recovery(rs, MaxSector);
+		rs_set_new(rs);
+	} else if (rs_reshape_requested(rs)) {
+		/*
+		  * We can only prepare for a reshape here, because the
+		  * raid set needs to run to provide the repective reshape
+		  * check functions via its MD personality instance.
+		  *
+		  * So do the reshape check after md_run() succeeded.
+		  */
+		r = rs_prepare_reshape(rs);
+		if (r)
+			return r;
+
+		/* Reshaping ain't recovery, so disable recovery */
+		rs_setup_recovery(rs, MaxSector);
+		rs_set_cur(rs);
+	} else {
+		/* May not set recovery when a device rebuild is requested */
+		if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags)) {
+			rs_setup_recovery(rs, MaxSector);
+			set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+		} else
+			rs_setup_recovery(rs, test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) ?
+					      0 : (resize ? calculated_dev_sectors : MaxSector));
+		rs_set_cur(rs);
+	}
+
+	/* If constructor requested it, change data and new_data offsets */
+	r = rs_adjust_data_offsets(rs);
+	if (r)
+		goto bad;
+
+	/* Start raid set read-only and assumed clean to change in raid_resume() */
+	rs->md.ro = 1;
+	rs->md.in_sync = 1;
+	set_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
 
 	/* Has to be held on running the array */
 	mddev_lock_nointr(&rs->md);
-	ret = md_run(&rs->md);
+	r = md_run(&rs->md);
 	rs->md.in_sync = 0; /* Assume already marked dirty */
-	mddev_unlock(&rs->md);
 
-	if (ret) {
-		ti->error = "Fail to run raid array";
+	if (r) {
+		ti->error = "Failed to run raid array";
+		mddev_unlock(&rs->md);
 		goto bad;
 	}
 
-	if (ti->len != rs->md.array_sectors) {
-		ti->error = "Array size does not match requested target length";
-		ret = -EINVAL;
-		goto size_mismatch;
-	}
 	rs->callbacks.congested_fn = raid_is_congested;
 	dm_table_add_target_callbacks(ti->table, &rs->callbacks);
 
 	mddev_suspend(&rs->md);
+
+	/* Try to adjust the raid4/5/6 stripe cache size to the stripe size */
+	if (rs_is_raid456(rs)) {
+		r = rs_set_raid456_stripe_cache(rs);
+		if (r)
+			goto bad_stripe_cache;
+	}
+
+	/* Now do an early reshape check */
+	if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
+		r = rs_check_reshape(rs);
+		if (r)
+			goto bad_check_reshape;
+
+		/* Restore new, ctr requested layout to perform check */
+		rs_config_restore(rs, &rs_layout);
+
+		if (rs->md.pers->start_reshape) {
+			r = rs->md.pers->check_reshape(&rs->md);
+			if (r) {
+				ti->error = "Reshape check failed";
+				goto bad_check_reshape;
+			}
+		}
+	}
+
+	mddev_unlock(&rs->md);
 	return 0;
 
-size_mismatch:
+bad_stripe_cache:
+bad_check_reshape:
 	md_stop(&rs->md);
 bad:
-	context_free(rs);
+	raid_set_free(rs);
 
-	return ret;
+	return r;
 }
 
 static void raid_dtr(struct dm_target *ti)
···
 
 	list_del_init(&rs->callbacks.list);
 	md_stop(&rs->md);
-	context_free(rs);
+	raid_set_free(rs);
 }
 
 static int raid_map(struct dm_target *ti, struct bio *bio)
···
 	struct raid_set *rs = ti->private;
 	struct mddev *mddev = &rs->md;
 
+	/*
+	 * If we're reshaping to add disk(s)), ti->len and
+	 * mddev->array_sectors will differ during the process
+	 * (ti->len > mddev->array_sectors), so we have to requeue
+	 * bios with addresses > mddev->array_sectors here or
+	 * there will occur accesses past EOD of the component
+	 * data images thus erroring the raid set.
+	 */
+	if (unlikely(bio_end_sector(bio) > mddev->array_sectors))
+		return DM_MAPIO_REQUEUE;
+
 	mddev->pers->make_request(mddev, bio);
 
 	return DM_MAPIO_SUBMITTED;
 }
 
+/* Return string describing the current sync action of @mddev */
 static const char *decipher_sync_action(struct mddev *mddev)
 {
 	if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
···
 	return "idle";
 }
 
-static void raid_status(struct dm_target *ti, status_type_t type,
-			unsigned status_flags, char *result, unsigned maxlen)
+/*
+ * Return status string @rdev
+ *
+ * Status characters:
+ *
+ *  'D' = Dead/Failed device
+ *  'a' = Alive but not in-sync
+ *  'A' = Alive and in-sync
+ */
+static const char *__raid_dev_status(struct md_rdev *rdev, bool array_in_sync)
 {
-	struct raid_set *rs = ti->private;
-	unsigned raid_param_cnt = 1; /* at least 1 for chunksize */
-	unsigned sz = 0;
-	int i, array_in_sync = 0;
-	sector_t sync;
-
-	switch (type) {
-	case STATUSTYPE_INFO:
-		DMEMIT("%s %d ", rs->raid_type->name, rs->md.raid_disks);
-
-		if (rs->raid_type->level) {
-			if (test_bit(MD_RECOVERY_RUNNING, &rs->md.recovery))
-				sync = rs->md.curr_resync_completed;
-			else
-				sync = rs->md.recovery_cp;
-
-			if (sync >= rs->md.resync_max_sectors) {
-				/*
-				 * Sync complete.
-				 */
-				array_in_sync = 1;
-				sync = rs->md.resync_max_sectors;
-			} else if (test_bit(MD_RECOVERY_REQUESTED, &rs->md.recovery)) {
-				/*
-				 * If "check" or "repair" is occurring, the array has
-				 * undergone and initial sync and the health characters
-				 * should not be 'a' anymore.
-				 */
-				array_in_sync = 1;
-			} else {
-				/*
-				 * The array may be doing an initial sync, or it may
-				 * be rebuilding individual components.  If all the
-				 * devices are In_sync, then it is the array that is
-				 * being initialized.
-				 */
-				for (i = 0; i < rs->md.raid_disks; i++)
-					if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
-						array_in_sync = 1;
-			}
-		} else {
-			/* RAID0 */
-			array_in_sync = 1;
-			sync = rs->md.resync_max_sectors;
-		}
-
-		/*
-		 * Status characters:
-		 *  'D' = Dead/Failed device
-		 *  'a' = Alive but not in-sync
-		 *  'A' = Alive and in-sync
-		 */
-		for (i = 0; i < rs->md.raid_disks; i++) {
-			if (test_bit(Faulty, &rs->dev[i].rdev.flags))
-				DMEMIT("D");
-			else if (!array_in_sync ||
-				 !test_bit(In_sync, &rs->dev[i].rdev.flags))
-				DMEMIT("a");
-			else
-				DMEMIT("A");
-		}
-
-		/*
-		 * In-sync ratio:
-		 *  The in-sync ratio shows the progress of:
-		 *   - Initializing the array
-		 *   - Rebuilding a subset of devices of the array
-		 *  The user can distinguish between the two by referring
-		 *  to the status characters.
-		 */
-		DMEMIT(" %llu/%llu",
-		       (unsigned long long) sync,
-		       (unsigned long long) rs->md.resync_max_sectors);
-
-		/*
-		 * Sync action:
-		 *   See Documentation/device-mapper/dm-raid.c for
-		 *   information on each of these states.
-		 */
-		DMEMIT(" %s", decipher_sync_action(&rs->md));
-
-		/*
-		 * resync_mismatches/mismatch_cnt
-		 *   This field shows the number of discrepancies found when
-		 *   performing a "check" of the array.
-		 */
-		DMEMIT(" %llu",
-		       (strcmp(rs->md.last_sync_action, "check")) ? 0 :
-		       (unsigned long long)
-		       atomic64_read(&rs->md.resync_mismatches));
-		break;
-	case STATUSTYPE_TABLE:
-		/* The string you would use to construct this array */
-		for (i = 0; i < rs->md.raid_disks; i++) {
-			if ((rs->ctr_flags & CTR_FLAG_REBUILD) &&
-			    rs->dev[i].data_dev &&
-			    !test_bit(In_sync, &rs->dev[i].rdev.flags))
-				raid_param_cnt += 2; /* for rebuilds */
-			if (rs->dev[i].data_dev &&
-			    test_bit(WriteMostly, &rs->dev[i].rdev.flags))
-				raid_param_cnt += 2;
-		}
-
-		raid_param_cnt += (hweight32(rs->ctr_flags & ~CTR_FLAG_REBUILD) * 2);
-		if (rs->ctr_flags & (CTR_FLAG_SYNC | CTR_FLAG_NOSYNC))
-			raid_param_cnt--;
-
-		DMEMIT("%s %u %u", rs->raid_type->name,
-		       raid_param_cnt, rs->md.chunk_sectors);
-
-		if ((rs->ctr_flags & CTR_FLAG_SYNC) &&
-		    (rs->md.recovery_cp == MaxSector))
-			DMEMIT(" sync");
-		if (rs->ctr_flags & CTR_FLAG_NOSYNC)
-			DMEMIT(" nosync");
-
-		for (i = 0; i < rs->md.raid_disks; i++)
-			if ((rs->ctr_flags & CTR_FLAG_REBUILD) &&
-			    rs->dev[i].data_dev &&
-			    !test_bit(In_sync, &rs->dev[i].rdev.flags))
-				DMEMIT(" rebuild %u", i);
-
-		if (rs->ctr_flags & CTR_FLAG_DAEMON_SLEEP)
-			DMEMIT(" daemon_sleep %lu",
-			       rs->md.bitmap_info.daemon_sleep);
-
-		if (rs->ctr_flags & CTR_FLAG_MIN_RECOVERY_RATE)
-			DMEMIT(" min_recovery_rate %d", rs->md.sync_speed_min);
-
-		if (rs->ctr_flags & CTR_FLAG_MAX_RECOVERY_RATE)
-			DMEMIT(" max_recovery_rate %d", rs->md.sync_speed_max);
-
-		for (i = 0; i < rs->md.raid_disks; i++)
-			if (rs->dev[i].data_dev &&
-			    test_bit(WriteMostly, &rs->dev[i].rdev.flags))
-				DMEMIT(" write_mostly %u", i);
-
-		if (rs->ctr_flags & CTR_FLAG_MAX_WRITE_BEHIND)
-			DMEMIT(" max_write_behind %lu",
-			       rs->md.bitmap_info.max_write_behind);
-
-		if (rs->ctr_flags & CTR_FLAG_STRIPE_CACHE) {
-			struct r5conf *conf = rs->md.private;
-
-			/* convert from kiB to sectors */
-			DMEMIT(" stripe_cache %d",
-			       conf ? conf->max_nr_stripes * 2 : 0);
-		}
-
-		if (rs->ctr_flags & CTR_FLAG_REGION_SIZE)
-			DMEMIT(" region_size %lu",
-			       rs->md.bitmap_info.chunksize >> 9);
-
-		if (rs->ctr_flags & CTR_FLAG_RAID10_COPIES)
-			DMEMIT(" raid10_copies %u",
-			       raid10_md_layout_to_copies(rs->md.layout));
-
-		if (rs->ctr_flags & CTR_FLAG_RAID10_FORMAT)
-			DMEMIT(" raid10_format %s",
-			       raid10_md_layout_to_format(rs->md.layout));
-
-		DMEMIT(" %d", rs->md.raid_disks);
-		for (i = 0; i < rs->md.raid_disks; i++) {
-			if (rs->dev[i].meta_dev)
-				DMEMIT(" %s", rs->dev[i].meta_dev->name);
-			else
-				DMEMIT(" -");
-
-			if (rs->dev[i].data_dev)
-				DMEMIT(" %s", rs->dev[i].data_dev->name);
-			else
-				DMEMIT(" -");
-		}
-	}
+	if (test_bit(Faulty, &rdev->flags))
+		return "D";
+	else if (!array_in_sync || !test_bit(In_sync, &rdev->flags))
+		return "a";
+	else
+		return "A";
 }
 
-static int raid_message(struct dm_target *ti, unsigned argc, char **argv)
+/* Helper to return resync/reshape progress for @rs and @array_in_sync */
+static sector_t rs_get_progress(struct raid_set *rs,
+				sector_t resync_max_sectors, bool *array_in_sync)
+{
+	sector_t r, recovery_cp, curr_resync_completed;
+	struct mddev *mddev = &rs->md;
+
+	curr_resync_completed = mddev->curr_resync_completed ?: mddev->recovery_cp;
+	recovery_cp = mddev->recovery_cp;
+	*array_in_sync = false;
+
+	if (rs_is_raid0(rs)) {
+		r = resync_max_sectors;
+		*array_in_sync = true;
+
+	} else {
+		r = mddev->reshape_position;
+
+		/* Reshape is relative to the array size */
+		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) ||
+		    r != MaxSector) {
+			if (r == MaxSector) {
+				*array_in_sync = true;
+				r = resync_max_sectors;
+			} else {
+				/* Got to reverse on backward reshape */
+				if (mddev->reshape_backwards)
+					r = mddev->array_sectors - r;
+
+				/* Devide by # of data stripes */
+				sector_div(r, mddev_data_stripes(rs));
+			}
+
+		/* Sync is relative to the component device size */
+		} else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+			r = curr_resync_completed;
+		else
+			r = recovery_cp;
+
+		if (r == MaxSector) {
+			/*
+			 * Sync complete.
+			 */
+			*array_in_sync = true;
+			r = resync_max_sectors;
+		} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+			/*
+			 * If "check" or "repair" is occurring, the raid set has
+			 * undergone an initial sync and the health characters
+			 * should not be 'a' anymore.
+			 */
+			*array_in_sync = true;
+		} else {
+			struct md_rdev *rdev;
+
+			/*
+			 * The raid set may be doing an initial sync, or it may
+			 * be rebuilding individual components.	 If all the
+			 * devices are In_sync, then it is the raid set that is
+			 * being initialized.
+			 */
+			rdev_for_each(rdev, mddev)
+				if (!test_bit(In_sync, &rdev->flags))
+					*array_in_sync = true;
+#if 0
+			r = 0; /* HM FIXME: TESTME: https://bugzilla.redhat.com/show_bug.cgi?id=1210637 ? */
+#endif
+		}
+	}
+
+	return r;
+}
+
+/* Helper to return @dev name or "-" if !@dev */
+static const char *__get_dev_name(struct dm_dev *dev)
+{
+	return dev ? dev->name : "-";
+}
+
+static void raid_status(struct dm_target *ti, status_type_t type,
+			unsigned int status_flags, char *result, unsigned int maxlen)
 {
 	struct raid_set *rs = ti->private;
 	struct mddev *mddev = &rs->md;
+	struct r5conf *conf = mddev->private;
+	int i, max_nr_stripes = conf ? conf->max_nr_stripes : 0;
+	bool array_in_sync;
+	unsigned int raid_param_cnt = 1; /* at least 1 for chunksize */
+	unsigned int sz = 0;
+	unsigned int rebuild_disks;
+	unsigned int write_mostly_params = 0;
+	sector_t progress, resync_max_sectors, resync_mismatches;
+	const char *sync_action;
+	struct raid_type *rt;
+	struct md_rdev *rdev;
 
-	if (!strcasecmp(argv[0], "reshape")) {
-		DMERR("Reshape not supported.");
-		return -EINVAL;
+	switch (type) {
+	case STATUSTYPE_INFO:
+		/* *Should* always succeed */
+		rt = get_raid_type_by_ll(mddev->new_level, mddev->new_layout);
+		if (!rt)
+			return;
+
+		DMEMIT("%s %d ", rt->name, mddev->raid_disks);
+
+		/* Access most recent mddev properties for status output */
+		smp_rmb();
+		/* Get sensible max sectors even if raid set not yet started */
+		resync_max_sectors = test_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags) ?
+				      mddev->resync_max_sectors : mddev->dev_sectors;
+		progress = rs_get_progress(rs, resync_max_sectors, &array_in_sync);
+		resync_mismatches = (mddev->last_sync_action && !strcasecmp(mddev->last_sync_action, "check")) ?
+				    atomic64_read(&mddev->resync_mismatches) : 0;
+		sync_action = decipher_sync_action(&rs->md);
+
+		/* HM FIXME: do we want another state char for raid0? It shows 'D' or 'A' now */
+		rdev_for_each(rdev, mddev)
+			DMEMIT(__raid_dev_status(rdev, array_in_sync));
+
+		/*
+		 * In-sync/Reshape ratio:
+		 *  The in-sync ratio shows the progress of:
+		 *   - Initializing the raid set
+		 *   - Rebuilding a subset of devices of the raid set
+		 *  The user can distinguish between the two by referring
+		 *  to the status characters.
+		 *
+		 *  The reshape ratio shows the progress of
+		 *  changing the raid layout or the number of
+		 *  disks of a raid set
+		 */
+		DMEMIT(" %llu/%llu", (unsigned long long) progress,
+				     (unsigned long long) resync_max_sectors);
+
+		/*
+		 * v1.5.0+:
+		 *
+		 * Sync action:
+		 *   See Documentation/device-mapper/dm-raid.txt for
+		 *   information on each of these states.
+		 */
+		DMEMIT(" %s", sync_action);
+
+		/*
+		 * v1.5.0+:
+		 *
+		 * resync_mismatches/mismatch_cnt
+		 *   This field shows the number of discrepancies found when
+		 *   performing a "check" of the raid set.
+		 */
+		DMEMIT(" %llu", (unsigned long long) resync_mismatches);
+
+		/*
+		 * v1.9.0+:
+		 *
+		 * data_offset (needed for out of space reshaping)
+		 *   This field shows the data offset into the data
+		 *   image LV where the first stripes data starts.
+		 *
+		 * We keep data_offset equal on all raid disks of the set,
+		 * so retrieving it from the first raid disk is sufficient.
+		 */
+		DMEMIT(" %llu", (unsigned long long) rs->dev[0].rdev.data_offset);
+		break;
+
+	case STATUSTYPE_TABLE:
+		/* Report the table line string you would use to construct this raid set */
+
+		/* Calculate raid parameter count */
+		for (i = 0; i < rs->raid_disks; i++)
+			if (test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+				write_mostly_params += 2;
+		rebuild_disks = memweight(rs->rebuild_disks, DISKS_ARRAY_ELEMS * sizeof(*rs->rebuild_disks));
+		raid_param_cnt += rebuild_disks * 2 +
+				  write_mostly_params +
+				  hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_NO_ARGS) +
+				  hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_ONE_ARG) * 2;
+		/* Emit table line */
+		DMEMIT("%s %u %u", rs->raid_type->name, raid_param_cnt, mddev->new_chunk_sectors);
+		if (test_bit(__CTR_FLAG_RAID10_FORMAT, &rs->ctr_flags))
+			DMEMIT(" %s %s", dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_FORMAT),
+					 raid10_md_layout_to_format(mddev->layout));
+		if (test_bit(__CTR_FLAG_RAID10_COPIES, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_COPIES),
+					 raid10_md_layout_to_copies(mddev->layout));
+		if (test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))
+			DMEMIT(" %s", dm_raid_arg_name_by_flag(CTR_FLAG_NOSYNC));
+		if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags))
+			DMEMIT(" %s", dm_raid_arg_name_by_flag(CTR_FLAG_SYNC));
+		if (test_bit(__CTR_FLAG_REGION_SIZE, &rs->ctr_flags))
+			DMEMIT(" %s %llu", dm_raid_arg_name_by_flag(CTR_FLAG_REGION_SIZE),
+					   (unsigned long long) to_sector(mddev->bitmap_info.chunksize));
+		if (test_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags))
+			DMEMIT(" %s %llu", dm_raid_arg_name_by_flag(CTR_FLAG_DATA_OFFSET),
+					   (unsigned long long) rs->data_offset);
+		if (test_bit(__CTR_FLAG_DAEMON_SLEEP, &rs->ctr_flags))
+			DMEMIT(" %s %lu", dm_raid_arg_name_by_flag(CTR_FLAG_DAEMON_SLEEP),
+					  mddev->bitmap_info.daemon_sleep);
+		if (test_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_DELTA_DISKS),
+					 max(rs->delta_disks, mddev->delta_disks));
+		if (test_bit(__CTR_FLAG_STRIPE_CACHE, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_STRIPE_CACHE),
+					 max_nr_stripes);
+		if (rebuild_disks)
+			for (i = 0; i < rs->raid_disks; i++)
+				if (test_bit(rs->dev[i].rdev.raid_disk, (void *) rs->rebuild_disks))
+					DMEMIT(" %s %u", dm_raid_arg_name_by_flag(CTR_FLAG_REBUILD),
+							 rs->dev[i].rdev.raid_disk);
+		if (write_mostly_params)
+			for (i = 0; i < rs->raid_disks; i++)
+				if (test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+					DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_WRITE_MOSTLY),
+					       rs->dev[i].rdev.raid_disk);
+		if (test_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags))
+			DMEMIT(" %s %lu", dm_raid_arg_name_by_flag(CTR_FLAG_MAX_WRITE_BEHIND),
+					  mddev->bitmap_info.max_write_behind);
+		if (test_bit(__CTR_FLAG_MAX_RECOVERY_RATE, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_MAX_RECOVERY_RATE),
+					 mddev->sync_speed_max);
+		if (test_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags))
+			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_MIN_RECOVERY_RATE),
+					 mddev->sync_speed_min);
+		DMEMIT(" %d", rs->raid_disks);
+		for (i = 0; i < rs->raid_disks; i++)
+			DMEMIT(" %s %s", __get_dev_name(rs->dev[i].meta_dev),
+					 __get_dev_name(rs->dev[i].data_dev));
 	}
+}
+
+static int raid_message(struct dm_target *ti, unsigned int argc, char **argv)
+{
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
 
 	if (!mddev->pers || !mddev->pers->sync_request)
 		return -EINVAL;
···
 		   test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
 		return -EBUSY;
 	else if (!strcasecmp(argv[0], "resync"))
-		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-	else if (!strcasecmp(argv[0], "recover")) {
+		; /* MD_RECOVERY_NEEDED set below */
+	else if (!strcasecmp(argv[0], "recover"))
 		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
-		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-	} else {
+	else {
 		if (!strcasecmp(argv[0], "check"))
 			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
 		else if (!!strcasecmp(argv[0], "repair"))
···
 		 * canceling read-auto mode
 		 */
 		mddev->ro = 0;
-		if (!mddev->suspended)
+		if (!mddev->suspended && mddev->sync_thread)
 			md_wakeup_thread(mddev->sync_thread);
 	}
 	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-	if (!mddev->suspended)
+	if (!mddev->suspended && mddev->thread)
 		md_wakeup_thread(mddev->thread);
 
 	return 0;
···
 				iterate_devices_callout_fn fn, void *data)
 {
 	struct raid_set *rs = ti->private;
-	unsigned i;
-	int ret = 0;
+	unsigned int i;
+	int r = 0;
 
-	for (i = 0; !ret && i < rs->md.raid_disks; i++)
+	for (i = 0; !r && i < rs->md.raid_disks; i++)
 		if (rs->dev[i].data_dev)
-			ret = fn(ti,
+			r = fn(ti,
 				 rs->dev[i].data_dev,
 				 0, /* No offset on data devs */
 				 rs->md.dev_sectors,
 				 data);
 
-	return ret;
+	return r;
 }
 
 static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
 	struct raid_set *rs = ti->private;
-	unsigned chunk_size = rs->md.chunk_sectors << 9;
-	struct r5conf *conf = rs->md.private;
+	unsigned int chunk_size = to_bytes(rs->md.chunk_sectors);
 
 	blk_limits_io_min(limits, chunk_size);
-	blk_limits_io_opt(limits, chunk_size * (conf->raid_disks - conf->max_degraded));
+	blk_limits_io_opt(limits, chunk_size * mddev_data_stripes(rs));
 }
 
 static void raid_presuspend(struct dm_target *ti)
···
 {
 	struct raid_set *rs = ti->private;
 
-	mddev_suspend(&rs->md);
+	if (test_and_clear_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags)) {
+		if (!rs->md.suspended)
+			mddev_suspend(&rs->md);
+		rs->md.ro = 1;
+	}
 }
 
 static void attempt_restore_of_faulty_devices(struct raid_set *rs)
···
 	for (i = 0; i < rs->md.raid_disks; i++) {
 		r = &rs->dev[i].rdev;
 		if (test_bit(Faulty, &r->flags) && r->sb_page &&
-		    sync_page_io(r, 0, r->sb_size, r->sb_page, REQ_OP_READ, 0,
-				 1)) {
+		    sync_page_io(r, 0, r->sb_size, r->sb_page,
+				 REQ_OP_READ, 0, true)) {
 			DMINFO("Faulty %s device #%d has readable super block."
 			       "  Attempting to revive it.",
 			       rs->raid_type->name, i);
···
 			 * Faulty bit may be set, but sometimes the array can
 			 * be suspended before the personalities can respond
 			 * by removing the device from the array (i.e. calling
-			 * 'hot_remove_disk').  If they haven't yet removed
+			 * 'hot_remove_disk').	If they haven't yet removed
 			 * the failed device, its 'raid_disk' number will be
 			 * '>= 0' - meaning we must call this function
 			 * ourselves.
···
 	}
 }
 
+static int __load_dirty_region_bitmap(struct raid_set *rs)
+{
+	int r = 0;
+
+	/* Try loading the bitmap unless "raid0", which does not have one */
+	if (!rs_is_raid0(rs) &&
+	    !test_and_set_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags)) {
+		r = bitmap_load(&rs->md);
+		if (r)
+			DMERR("Failed to load bitmap");
+	}
+
+	return r;
+}
+
+/* Enforce updating all superblocks */
+static void rs_update_sbs(struct raid_set *rs)
+{
+	struct mddev *mddev = &rs->md;
+	int ro = mddev->ro;
+
+	set_bit(MD_CHANGE_DEVS, &mddev->flags);
+	mddev->ro = 0;
+	md_update_sb(mddev, 1);
+	mddev->ro = ro;
+}
+
+/*
+ * Reshape changes raid algorithm of @rs to new one within personality
+ * (e.g. raid6_zr -> raid6_nc), changes stripe size, adds/removes
+ * disks from a raid set thus growing/shrinking it or resizes the set
+ *
+ * Call mddev_lock_nointr() before!
+ */
+static int rs_start_reshape(struct raid_set *rs)
+{
+	int r;
+	struct mddev *mddev = &rs->md;
+	struct md_personality *pers = mddev->pers;
+
+	r = rs_setup_reshape(rs);
+	if (r)
+		return r;
+
+	/* Need to be resumed to be able to start reshape, recovery is frozen until raid_resume() though */
+	if (mddev->suspended)
+		mddev_resume(mddev);
+
+	/*
+	 * Check any reshape constraints enforced by the personalility
+	 *
+	 * May as well already kick the reshape off so that * pers->start_reshape() becomes optional.
+	 */
+	r = pers->check_reshape(mddev);
+	if (r) {
+		rs->ti->error = "pers->check_reshape() failed";
+		return r;
+	}
+
+	/*
+	 * Personality may not provide start reshape method in which
+	 * case check_reshape above has already covered everything
+	 */
+	if (pers->start_reshape) {
+		r = pers->start_reshape(mddev);
+		if (r) {
+			rs->ti->error = "pers->start_reshape() failed";
+			return r;
+		}
+	}
+
+	/* Suspend because a resume will happen in raid_resume() */
+	if (!mddev->suspended)
+		mddev_suspend(mddev);
+
+	/*
+	 * Now reshape got set up, update superblocks to
+	 * reflect the fact so that a table reload will
+	 * access proper superblock content in the ctr.
+	 */
+	rs_update_sbs(rs);
+
+	return 0;
+}
+
+static int raid_preresume(struct dm_target *ti)
+{
+	int r;
+	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
+
+	/* This is a resume after a suspend of the set -> it's already started */
+	if (test_and_set_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags))
+		return 0;
+
+	/*
+	 * The superblocks need to be updated on disk if the
+	 * array is new or new devices got added (thus zeroed
+	 * out by userspace) or __load_dirty_region_bitmap
+	 * will overwrite them in core with old data or fail.
+	 */
+	if (test_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags))
+		rs_update_sbs(rs);
+
+	/*
+	 * Disable/enable discard support on raid set after any
+	 * conversion, because devices can have been added
+	 */
+	configure_discard_support(rs);
+
+	/* Load the bitmap from disk unless raid0 */
+	r = __load_dirty_region_bitmap(rs);
+	if (r)
+		return r;
+
+	/* Resize bitmap to adjust to changed region size (aka MD bitmap chunksize) */
+	if (test_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags) &&
+	    mddev->bitmap_info.chunksize != to_bytes(rs->requested_bitmap_chunk_sectors)) {
+		r = bitmap_resize(mddev->bitmap, mddev->dev_sectors,
+				  to_bytes(rs->requested_bitmap_chunk_sectors), 0);
+		if (r)
+			DMERR("Failed to resize bitmap");
+	}
+
+	/* Check for any resize/reshape on @rs and adjust/initiate */
+	/* Be prepared for mddev_resume() in raid_resume() */
+	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	if (mddev->recovery_cp && mddev->recovery_cp < MaxSector) {
+		set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+		mddev->resync_min = mddev->recovery_cp;
+	}
+
+	rs_set_capacity(rs);
+
+	/* Check for any reshape request unless new raid set */
+	if (test_and_clear_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
+		/* Initiate a reshape. */
+		mddev_lock_nointr(mddev);
+		r = rs_start_reshape(rs);
+		mddev_unlock(mddev);
+		if (r)
+			DMWARN("Failed to check/start reshape, continuing without change");
+		r = 0;
+	}
+
+	return r;
+}
+
 static void raid_resume(struct dm_target *ti)
 {
 	struct raid_set *rs = ti->private;
+	struct mddev *mddev = &rs->md;
 
-	if (rs->raid_type->level) {
-		set_bit(MD_CHANGE_DEVS, &rs->md.flags);
+	if (test_and_set_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags)) {
+		/*
+		 * A secondary resume while the device is active.
+		 * Take this opportunity to check whether any failed
+		 * devices are reachable again.
+		 */
+		attempt_restore_of_faulty_devices(rs);
+	} else {
+		mddev->ro = 0;
+		mddev->in_sync = 0;
 
-		if (!rs->bitmap_loaded) {
-			bitmap_load(&rs->md);
-			rs->bitmap_loaded = 1;
-		} else {
-			/*
-			 * A secondary resume while the device is active.
-			 * Take this opportunity to check whether any failed
-			 * devices are reachable again.
-			 */
-			attempt_restore_of_faulty_devices(rs);
-		}
+		/*
+		 * When passing in flags to the ctr, we expect userspace
+		 * to reset them because they made it to the superblocks
+		 * and reload the mapping anyway.
+		 *
+		 * -> only unfreeze recovery in case of a table reload or
+		 *    we'll have a bogus recovery/reshape position
+		 *    retrieved from the superblock by the ctr because
+		 *    the ongoing recovery/reshape will change it after read.
+		 */
+		if (!test_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags))
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 
-		clear_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
+		if (mddev->suspended)
+			mddev_resume(mddev);
 	}
-
-	mddev_resume(&rs->md);
 }
 
 static struct target_type raid_target = {
 	.name = "raid",
-	.version = {1, 8, 0},
+	.version = {1, 9, 0},
 	.module = THIS_MODULE,
 	.ctr = raid_ctr,
 	.dtr = raid_dtr,
···
 	.io_hints = raid_io_hints,
 	.presuspend = raid_presuspend,
 	.postsuspend = raid_postsuspend,
+	.preresume = raid_preresume,
 	.resume = raid_resume,
 };
 
···
 MODULE_PARM_DESC(devices_handle_discard_safely,
 		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
 
-MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target");
+MODULE_DESCRIPTION(DM_NAME " raid0/1/10/4/5/6 target");
+MODULE_ALIAS("dm-raid0");
 MODULE_ALIAS("dm-raid1");
 MODULE_ALIAS("dm-raid10");
 MODULE_ALIAS("dm-raid4");
 MODULE_ALIAS("dm-raid5");
 MODULE_ALIAS("dm-raid6");
 MODULE_AUTHOR("Neil Brown <[e-mail]>");
+MODULE_AUTHOR("Heinz Mauelshagen <[e-mail]>");
 MODULE_LICENSE("GPL");

drivers/md/dm-rq.c

···
+/*
+ * Copyright (C) 2016 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-core.h"
+#include "dm-rq.h"
+
+#include <linux/elevator.h> /* for rq_end_sector() */
+#include <linux/blk-mq.h>
+
+#define DM_MSG_PREFIX "core-rq"
+
+#define DM_MQ_NR_HW_QUEUES 1
+#define DM_MQ_QUEUE_DEPTH 2048
+static unsigned dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES;
+static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;
+
+/*
+ * Request-based DM's mempools' reserved IOs set by the user.
+ */
+#define RESERVED_REQUEST_BASED_IOS	256
+static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
+
+#ifdef CONFIG_DM_MQ_DEFAULT
+static bool use_blk_mq = true;
+#else
+static bool use_blk_mq = false;
+#endif
+
+bool dm_use_blk_mq_default(void)
+{
+	return use_blk_mq;
+}
+
+bool dm_use_blk_mq(struct mapped_device *md)
+{
+	return md->use_blk_mq;
+}
+EXPORT_SYMBOL_GPL(dm_use_blk_mq);
+
+unsigned dm_get_reserved_rq_based_ios(void)
+{
+	return __dm_get_module_param(&reserved_rq_based_ios,
+				     RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS);
+}
+EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
+
+static unsigned dm_get_blk_mq_nr_hw_queues(void)
+{
+	return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32);
+}
+
+static unsigned dm_get_blk_mq_queue_depth(void)
+{
+	return __dm_get_module_param(&dm_mq_queue_depth,
+				     DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);
+}
+
+int dm_request_based(struct mapped_device *md)
+{
+	return blk_queue_stackable(md->queue);
+}
+
+static void dm_old_start_queue(struct request_queue *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	if (blk_queue_stopped(q))
+		blk_start_queue(q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+void dm_start_queue(struct request_queue *q)
+{
+	if (!q->mq_ops)
+		dm_old_start_queue(q);
+	else {
+		blk_mq_start_stopped_hw_queues(q, true);
+		blk_mq_kick_requeue_list(q);
+	}
+}
+
+static void dm_old_stop_queue(struct request_queue *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	if (blk_queue_stopped(q)) {
+		spin_unlock_irqrestore(q->queue_lock, flags);
+		return;
+	}
+
+	blk_stop_queue(q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+void dm_stop_queue(struct request_queue *q)
+{
+	if (!q->mq_ops)
+		dm_old_stop_queue(q);
+	else
+		blk_mq_stop_hw_queues(q);
+}
+
+static struct dm_rq_target_io *alloc_old_rq_tio(struct mapped_device *md,
+						gfp_t gfp_mask)
+{
+	return mempool_alloc(md->io_pool, gfp_mask);
+}
+
+static void free_old_rq_tio(struct dm_rq_target_io *tio)
+{
+	mempool_free(tio, tio->md->io_pool);
+}
+
+static struct request *alloc_old_clone_request(struct mapped_device *md,
+					       gfp_t gfp_mask)
+{
+	return mempool_alloc(md->rq_pool, gfp_mask);
+}
+
+static void free_old_clone_request(struct mapped_device *md, struct request *rq)
+{
+	mempool_free(rq, md->rq_pool);
+}
+
+/*
+ * Partial completion handling for request-based dm
+ */
+static void end_clone_bio(struct bio *clone)
+{
+	struct dm_rq_clone_bio_info *info =
+		container_of(clone, struct dm_rq_clone_bio_info, clone);
+	struct dm_rq_target_io *tio = info->tio;
+	struct bio *bio = info->orig;
+	unsigned int nr_bytes = info->orig->bi_iter.bi_size;
+	int error = clone->bi_error;
+
+	bio_put(clone);
+
+	if (tio->error)
+		/*
+		 * An error has already been detected on the request.
+		 * Once error occurred, just let clone->end_io() handle
+		 * the remainder.
+		 */
+		return;
+	else if (error) {
+		/*
+		 * Don't notice the error to the upper layer yet.
+		 * The error handling decision is made by the target driver,
+		 * when the request is completed.
+		 */
+		tio->error = error;
+		return;
+	}
+
+	/*
+	 * I/O for the bio successfully completed.
+	 * Notice the data completion to the upper layer.
+	 */
+
+	/*
+	 * bios are processed from the head of the list.
+	 * So the completing bio should always be rq->bio.
+	 * If it's not, something wrong is happening.
+	 */
+	if (tio->orig->bio != bio)
+		DMERR("bio completion is going in the middle of the request");
+
+	/*
+	 * Update the original request.
+	 * Do not use blk_end_request() here, because it may complete
+	 * the original request before the clone, and break the ordering.
+	 */
+	blk_update_request(tio->orig, 0, nr_bytes);
+}
+
+static struct dm_rq_target_io *tio_from_request(struct request *rq)
+{
+	return (rq->q->mq_ops ? blk_mq_rq_to_pdu(rq) : rq->special);
+}
+
+static void rq_end_stats(struct mapped_device *md, struct request *orig)
+{
+	if (unlikely(dm_stats_used(&md->stats))) {
+		struct dm_rq_target_io *tio = tio_from_request(orig);
+		tio->duration_jiffies = jiffies - tio->duration_jiffies;
+		dm_stats_account_io(&md->stats, rq_data_dir(orig),
+				    blk_rq_pos(orig), tio->n_sectors, true,
+				    tio->duration_jiffies, &tio->stats_aux);
+	}
+}
+
+/*
+ * Don't touch any member of the md after calling this function because
+ * the md may be freed in dm_put() at the end of this function.
+ * Or do dm_get() before calling this function and dm_put() later.
+ */
+static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
+{
+	atomic_dec(&md->pending[rw]);
+
+	/* nudge anyone waiting on suspend queue */
+	if (!md_in_flight(md))
+		wake_up(&md->wait);
+
+	/*
+	 * Run this off this callpath, as drivers could invoke end_io while
+	 * inside their request_fn (and holding the queue lock). Calling
+	 * back into ->request_fn() could deadlock attempting to grab the
+	 * queue lock again.
+	 */
+	if (!md->queue->mq_ops && run_queue)
+		blk_run_queue_async(md->queue);
+
+	/*
+	 * dm_put() must be at the end of this function. See the comment above
+	 */
+	dm_put(md);
+}
+
+static void free_rq_clone(struct request *clone)
+{
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	struct mapped_device *md = tio->md;
+
+	blk_rq_unprep_clone(clone);
+
+	/*
+	 * It is possible for a clone_old_rq() allocated clone to
+	 * get passed in -- it may not yet have a request_queue.
+	 * This is known to occur if the error target replaces
+	 * a multipath target that has a request_fn queue stacked
+	 * on blk-mq queue(s).
+	 */
+	if (clone->q && clone->q->mq_ops)
+		/* stacked on blk-mq queue(s) */
+		tio->ti->type->release_clone_rq(clone);
+	else if (!md->queue->mq_ops)
+		/* request_fn queue stacked on request_fn queue(s) */
+		free_old_clone_request(md, clone);
+
+	if (!md->queue->mq_ops)
+		free_old_rq_tio(tio);
+}
+
+/*
+ * Complete the clone and the original request.
+ * Must be called without clone's queue lock held,
+ * see end_clone_request() for more details.
+ */
+static void dm_end_request(struct request *clone, int error)
+{
+	int rw = rq_data_dir(clone);
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	struct mapped_device *md = tio->md;
+	struct request *rq = tio->orig;
+
+	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
+		rq->errors = clone->errors;
+		rq->resid_len = clone->resid_len;
+
+		if (rq->sense)
+			/*
+			 * We are using the sense buffer of the original
+			 * request.
+			 * So setting the length of the sense data is enough.
+			 */
+			rq->sense_len = clone->sense_len;
+	}
+
+	free_rq_clone(clone);
+	rq_end_stats(md, rq);
+	if (!rq->q->mq_ops)
+		blk_end_request_all(rq, error);
+	else
+		blk_mq_end_request(rq, error);
+	rq_completed(md, rw, true);
+}
+
+static void dm_unprep_request(struct request *rq)
+{
+	struct dm_rq_target_io *tio = tio_from_request(rq);
+	struct request *clone = tio->clone;
+
+	if (!rq->q->mq_ops) {
+		rq->special = NULL;
+		rq->cmd_flags &= ~REQ_DONTPREP;
+	}
+
+	if (clone)
+		free_rq_clone(clone);
+	else if (!tio->md->queue->mq_ops)
+		free_old_rq_tio(tio);
+}
+
+/*
+ * Requeue the original request of a clone.
+ */
+static void dm_old_requeue_request(struct request *rq)
+{
+	struct request_queue *q = rq->q;
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	blk_requeue_request(q, rq);
+	blk_run_queue_async(q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static void dm_mq_requeue_request(struct request *rq)
+{
+	struct request_queue *q = rq->q;
+	unsigned long flags;
+
+	blk_mq_requeue_request(rq);
+	spin_lock_irqsave(q->queue_lock, flags);
+	if (!blk_queue_stopped(q))
+		blk_mq_kick_requeue_list(q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static void dm_requeue_original_request(struct mapped_device *md,
+					struct request *rq)
+{
+	int rw = rq_data_dir(rq);
+
+	rq_end_stats(md, rq);
+	dm_unprep_request(rq);
+
+	if (!rq->q->mq_ops)
+		dm_old_requeue_request(rq);
+	else
+		dm_mq_requeue_request(rq);
+
+	rq_completed(md, rw, false);
+}
+
+static void dm_done(struct request *clone, int error, bool mapped)
+{
+	int r = error;
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	dm_request_endio_fn rq_end_io = NULL;
+
+	if (tio->ti) {
+		rq_end_io = tio->ti->type->rq_end_io;
+
+		if (mapped && rq_end_io)
+			r = rq_end_io(tio->ti, clone, error, &tio->info);
+	}
+
+	if (unlikely(r == -EREMOTEIO && (req_op(clone) == REQ_OP_WRITE_SAME) &&
+		     !clone->q->limits.max_write_same_sectors))
+		disable_write_same(tio->md);
+
+	if (r <= 0)
+		/* The target wants to complete the I/O */
+		dm_end_request(clone, r);
+	else if (r == DM_ENDIO_INCOMPLETE)
+		/* The target will handle the I/O */
+		return;
+	else if (r == DM_ENDIO_REQUEUE)
+		/* The target wants to requeue the I/O */
+		dm_requeue_original_request(tio->md, tio->orig);
+	else {
+		DMWARN("unimplemented target endio return value: %d", r);
+		BUG();
+	}
+}
+
+/*
+ * Request completion handler for request-based dm
+ */
+static void dm_softirq_done(struct request *rq)
+{
+	bool mapped = true;
+	struct dm_rq_target_io *tio = tio_from_request(rq);
+	struct request *clone = tio->clone;
+	int rw;
+
+	if (!clone) {
+		rq_end_stats(tio->md, rq);
+		rw = rq_data_dir(rq);
+		if (!rq->q->mq_ops) {
+			blk_end_request_all(rq, tio->error);
+			rq_completed(tio->md, rw, false);
+			free_old_rq_tio(tio);
+		} else {
+			blk_mq_end_request(rq, tio->error);
+			rq_completed(tio->md, rw, false);
+		}
+		return;
+	}
+
+	if (rq->cmd_flags & REQ_FAILED)
+		mapped = false;
+
+	dm_done(clone, tio->error, mapped);
+}
+
+/*
+ * Complete the clone and the original request with the error status
+ * through softirq context.
+ */
+static void dm_complete_request(struct request *rq, int error)
+{
+	struct dm_rq_target_io *tio = tio_from_request(rq);
+
+	tio->error = error;
+	if (!rq->q->mq_ops)
+		blk_complete_request(rq);
+	else
+		blk_mq_complete_request(rq, error);
+}
+
+/*
+ * Complete the not-mapped clone and the original request with the error status
+ * through softirq context.
+ * Target's rq_end_io() function isn't called.
+ * This may be used when the target's map_rq() or clone_and_map_rq() functions fail.
+ */
+static void dm_kill_unmapped_request(struct request *rq, int error)
+{
+	rq->cmd_flags |= REQ_FAILED;
+	dm_complete_request(rq, error);
+}
+
+/*
+ * Called with the clone's queue lock held (in the case of .request_fn)
+ */
+static void end_clone_request(struct request *clone, int error)
+{
+	struct dm_rq_target_io *tio = clone->end_io_data;
+
+	if (!clone->q->mq_ops) {
+		/*
+		 * For just cleaning up the information of the queue in which
+		 * the clone was dispatched.
+		 * The clone is *NOT* freed actually here because it is alloced
+		 * from dm own mempool (REQ_ALLOCED isn't set).
+		 */
+		__blk_put_request(clone->q, clone);
+	}
+
+	/*
+	 * Actual request completion is done in a softirq context which doesn't
+	 * hold the clone's queue lock.  Otherwise, deadlock could occur because:
+	 *     - another request may be submitted by the upper level driver
+	 *       of the stacking during the completion
+	 *     - the submission which requires queue lock may be done
+	 *       against this clone's queue
+	 */
+	dm_complete_request(tio->orig, error);
+}
+
+static void dm_dispatch_clone_request(struct request *clone, struct request *rq)
+{
+	int r;
+
+	if (blk_queue_io_stat(clone->q))
+		clone->cmd_flags |= REQ_IO_STAT;
+
+	clone->start_time = jiffies;
+	r = blk_insert_cloned_request(clone->q, clone);
+	if (r)
+		/* must complete clone in terms of original request */
+		dm_complete_request(rq, r);
+}
+
+static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
+				 void *data)
+{
+	struct dm_rq_target_io *tio = data;
+	struct dm_rq_clone_bio_info *info =
+		container_of(bio, struct dm_rq_clone_bio_info, clone);
+
+	info->orig = bio_orig;
+	info->tio = tio;
+	bio->bi_end_io = end_clone_bio;
+
+	return 0;
+}
+
+static int setup_clone(struct request *clone, struct request *rq,
+		       struct dm_rq_target_io *tio, gfp_t gfp_mask)
+{
+	int r;
+
+	r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask,
+			      dm_rq_bio_constructor, tio);
+	if (r)
+		return r;
+
+	clone->cmd = rq->cmd;
+	clone->cmd_len = rq->cmd_len;
+	clone->sense = rq->sense;
+	clone->end_io = end_clone_request;
+	clone->end_io_data = tio;
+
+	tio->clone = clone;
+
+	return 0;
+}
+
+static struct request *clone_old_rq(struct request *rq, struct mapped_device *md,
+				    struct dm_rq_target_io *tio, gfp_t gfp_mask)
+{
+	/*
+	 * Create clone for use with .request_fn request_queue
+	 */
+	struct request *clone;
+
+	clone = alloc_old_clone_request(md, gfp_mask);
+	if (!clone)
+		return NULL;
+
+	blk_rq_init(NULL, clone);
+	if (setup_clone(clone, rq, tio, gfp_mask)) {
+		/* -ENOMEM */
+		free_old_clone_request(md, clone);
+		return NULL;
+	}
+
+	return clone;
+}
+
+static void map_tio_request(struct kthread_work *work);
+
+static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
+		     struct mapped_device *md)
+{
+	tio->md = md;
+	tio->ti = NULL;
+	tio->clone = NULL;
+	tio->orig = rq;
+	tio->error = 0;
+	/*
+	 * Avoid initializing info for blk-mq; it passes
+	 * target-specific data through info.ptr
+	 * (see: dm_mq_init_request)
+	 */
+	if (!md->init_tio_pdu)
+		memset(&tio->info, 0, sizeof(tio->info));
+	if (md->kworker_task)
+		init_kthread_work(&tio->work, map_tio_request);
+}
+
+static struct dm_rq_target_io *dm_old_prep_tio(struct request *rq,
+					       struct mapped_device *md,
+					       gfp_t gfp_mask)
+{
+	struct dm_rq_target_io *tio;
+	int srcu_idx;
+	struct dm_table *table;
+
+	tio = alloc_old_rq_tio(md, gfp_mask);
+	if (!tio)
+		return NULL;
+
+	init_tio(tio, rq, md);
+
+	table = dm_get_live_table(md, &srcu_idx);
+	/*
+	 * Must clone a request if this .request_fn DM device
+	 * is stacked on .request_fn device(s).
+	 */
+	if (!dm_table_all_blk_mq_devices(table)) {
+		if (!clone_old_rq(rq, md, tio, gfp_mask)) {
+			dm_put_live_table(md, srcu_idx);
+			free_old_rq_tio(tio);
+			return NULL;
+		}
+	}
+	dm_put_live_table(md, srcu_idx);
+
+	return tio;
+}
+
+/*
+ * Called with the queue lock held.
+ */
+static int dm_old_prep_fn(struct request_queue *q, struct request *rq)
+{
+	struct mapped_device *md = q->queuedata;
+	struct dm_rq_target_io *tio;
+
+	if (unlikely(rq->special)) {
+		DMWARN("Already has something in rq->special.");
+		return BLKPREP_KILL;
+	}
+
+	tio = dm_old_prep_tio(rq, md, GFP_ATOMIC);
+	if (!tio)
+		return BLKPREP_DEFER;
+
+	rq->special = tio;
+	rq->cmd_flags |= REQ_DONTPREP;
+
+	return BLKPREP_OK;
+}
+
+/*
+ * Returns:
+ * 0                : the request has been processed
+ * DM_MAPIO_REQUEUE : the original request needs to be requeued
+ * < 0              : the request was completed due to failure
+ */
+static int map_request(struct dm_rq_target_io *tio, struct request *rq,
+		       struct mapped_device *md)
+{
+	int r;
+	struct dm_target *ti = tio->ti;
+	struct request *clone = NULL;
+
+	if (tio->clone) {
+		clone = tio->clone;
+		r = ti->type->map_rq(ti, clone, &tio->info);
+	} else {
+		r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
+		if (r < 0) {
+			/* The target wants to complete the I/O */
+			dm_kill_unmapped_request(rq, r);
+			return r;
+		}
+		if (r != DM_MAPIO_REMAPPED)
+			return r;
+		if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
+			/* -ENOMEM */
+			ti->type->release_clone_rq(clone);
+			return DM_MAPIO_REQUEUE;
+		}
+	}
+
+	switch (r) {
+	case DM_MAPIO_SUBMITTED:
+		/* The target has taken the I/O to submit by itself later */
+		break;
+	case DM_MAPIO_REMAPPED:
+		/* The target has remapped the I/O so dispatch it */
+		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
+				     blk_rq_pos(rq));
+		dm_dispatch_clone_request(clone, rq);
+		break;
+	case DM_MAPIO_REQUEUE:
+		/* The target wants to requeue the I/O */
+		dm_requeue_original_request(md, tio->orig);
+		break;
+	default:
+		if (r > 0) {
+			DMWARN("unimplemented target map return value: %d", r);
+			BUG();
+		}
+
+		/* The target wants to complete the I/O */
+		dm_kill_unmapped_request(rq, r);
+		return r;
+	}
+
+	return 0;
+}
+
+static void dm_start_request(struct mapped_device *md, struct request *orig)
+{
+	if (!orig->q->mq_ops)
+		blk_start_request(orig);
+	else
+		blk_mq_start_request(orig);
+	atomic_inc(&md->pending[rq_data_dir(orig)]);
+
+	if (md->seq_rq_merge_deadline_usecs) {
+		md->last_rq_pos = rq_end_sector(orig);
+		md->last_rq_rw = rq_data_dir(orig);
+		md->last_rq_start_time = ktime_get();
+	}
+
+	if (unlikely(dm_stats_used(&md->stats))) {
+		struct dm_rq_target_io *tio = tio_from_request(orig);
+		tio->duration_jiffies = jiffies;
+		tio->n_sectors = blk_rq_sectors(orig);
+		dm_stats_account_io(&md->stats, rq_data_dir(orig),
+				    blk_rq_pos(orig), tio->n_sectors, false, 0,
+				    &tio->stats_aux);
+	}
+
+	/*
+	 * Hold the md reference here for the in-flight I/O.
+	 * We can't rely on the reference count by device opener,
+	 * because the device may be closed during the request completion
+	 * when all bios are completed.
+	 * See the comment in rq_completed() too.
+	 */
+	dm_get(md);
+}
+
+static void map_tio_request(struct kthread_work *work)
+{
+	struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work);
+	struct request *rq = tio->orig;
+	struct mapped_device *md = tio->md;
+
+	if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE)
+		dm_requeue_original_request(md, rq);
+}
+
+ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
+{
+	return sprintf(buf, "%u\n", md->seq_rq_merge_deadline_usecs);
+}
+
+#define MAX_SEQ_RQ_MERGE_DEADLINE_USECS 100000
+
+ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
+						     const char *buf, size_t count)
+{
+	unsigned deadline;
+
+	if (dm_get_md_type(md) != DM_TYPE_REQUEST_BASED)
+		return count;
+
+	if (kstrtouint(buf, 10, &deadline))
+		return -EINVAL;
+
+	if (deadline > MAX_SEQ_RQ_MERGE_DEADLINE_USECS)
+		deadline = MAX_SEQ_RQ_MERGE_DEADLINE_USECS;
+
+	md->seq_rq_merge_deadline_usecs = deadline;
+
+	return count;
+}
+
+static bool dm_old_request_peeked_before_merge_deadline(struct mapped_device *md)
+{
+	ktime_t kt_deadline;
+
+	if (!md->seq_rq_merge_deadline_usecs)
+		return false;
+
+	kt_deadline = ns_to_ktime((u64)md->seq_rq_merge_deadline_usecs * NSEC_PER_USEC);
+	kt_deadline = ktime_add_safe(md->last_rq_start_time, kt_deadline);
+
+	return !ktime_after(ktime_get(), kt_deadline);
+}
+
+/*
+ * q->request_fn for old request-based dm.
+ * Called with the queue lock held.
+ */
+static void dm_old_request_fn(struct request_queue *q)
+{
+	struct mapped_device *md = q->queuedata;
+	struct dm_target *ti = md->immutable_target;
+	struct request *rq;
+	struct dm_rq_target_io *tio;
+	sector_t pos = 0;
+
+	if (unlikely(!ti)) {
+		int srcu_idx;
+		struct dm_table *map = dm_get_live_table(md, &srcu_idx);
+
+		ti = dm_table_find_target(map, pos);
+		dm_put_live_table(md, srcu_idx);
+	}
+
+	/*
+	 * For suspend, check blk_queue_stopped() and increment
+	 * ->pending within a single queue_lock not to increment the
+	 * number of in-flight I/Os after the queue is stopped in
+	 * dm_suspend().
+	 */
+	while (!blk_queue_stopped(q)) {
+		rq = blk_peek_request(q);
+		if (!rq)
+			return;
+
+		/* always use block 0 to find the target for flushes for now */
+		pos = 0;
+		if (req_op(rq) != REQ_OP_FLUSH)
+			pos = blk_rq_pos(rq);
+
+		if ((dm_old_request_peeked_before_merge_deadline(md) &&
+		     md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&
+		     md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
+		    (ti->type->busy && ti->type->busy(ti))) {
+			blk_delay_queue(q, 10);
+			return;
+		}
+
+		dm_start_request(md, rq);
+
+		tio = tio_from_request(rq);
+		/* Establish tio->ti before queuing work (map_tio_request) */
+		tio->ti = ti;
+		queue_kthread_work(&md->kworker, &tio->work);
+		BUG_ON(!irqs_disabled());
+	}
+}
+
+/*
+ * Fully initialize a .request_fn request-based queue.
+ */
+int dm_old_init_request_queue(struct mapped_device *md)
+{
+	/* Fully initialize the queue */
+	if (!blk_init_allocated_queue(md->queue, dm_old_request_fn, NULL))
+		return -EINVAL;
+
+	/* 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);
+	blk_queue_prep_rq(md->queue, dm_old_prep_fn);
+
+	/* Initialize the request-based DM worker thread */
+	init_kthread_worker(&md->kworker);
+	md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker,
+				       "kdmwork-%s", dm_device_name(md));
+	if (IS_ERR(md->kworker_task))
+		return PTR_ERR(md->kworker_task);
+
+	elv_register_queue(md->queue);
+
+	return 0;
+}
+
+static int dm_mq_init_request(void *data, struct request *rq,
+		       unsigned int hctx_idx, unsigned int request_idx,
+		       unsigned int numa_node)
+{
+	struct mapped_device *md = data;
+	struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
+
+	/*
+	 * Must initialize md member of tio, otherwise it won't
+	 * be available in dm_mq_queue_rq.
+	 */
+	tio->md = md;
+
+	if (md->init_tio_pdu) {
+		/* target-specific per-io data is immediately after the tio */
+		tio->info.ptr = tio + 1;
+	}
+
+	return 0;
+}
+
+static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
+			  const struct blk_mq_queue_data *bd)
+{
+	struct request *rq = bd->rq;
+	struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
+	struct mapped_device *md = tio->md;
+	struct dm_target *ti = md->immutable_target;
+
+	if (unlikely(!ti)) {
+		int srcu_idx;
+		struct dm_table *map = dm_get_live_table(md, &srcu_idx);
+
+		ti = dm_table_find_target(map, 0);
+		dm_put_live_table(md, srcu_idx);
+	}
+
+	if (ti->type->busy && ti->type->busy(ti))
+		return BLK_MQ_RQ_QUEUE_BUSY;
+
+	dm_start_request(md, rq);
+
+	/* Init tio using md established in .init_request */
+	init_tio(tio, rq, md);
+
+	/*
+	 * Establish tio->ti before calling map_request().
+	 */
+	tio->ti = ti;
+
+	/* Direct call is fine since .queue_rq allows allocations */
+	if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) {
+		/* Undo dm_start_request() before requeuing */
+		rq_end_stats(md, rq);
+		rq_completed(md, rq_data_dir(rq), false);
+		return BLK_MQ_RQ_QUEUE_BUSY;
+	}
+
+	return BLK_MQ_RQ_QUEUE_OK;
+}
+
+static struct blk_mq_ops dm_mq_ops = {
+	.queue_rq = dm_mq_queue_rq,
+	.map_queue = blk_mq_map_queue,
+	.complete = dm_softirq_done,
+	.init_request = dm_mq_init_request,
+};
+
+int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
+{
+	struct request_queue *q;
+	struct dm_target *immutable_tgt;
+	int err;
+
+	if (!dm_table_all_blk_mq_devices(t)) {
+		DMERR("request-based dm-mq may only be stacked on blk-mq device(s)");
+		return -EINVAL;
+	}
+
+	md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
+	if (!md->tag_set)
+		return -ENOMEM;
+
+	md->tag_set->ops = &dm_mq_ops;
+	md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
+	md->tag_set->numa_node = md->numa_node_id;
+	md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
+	md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
+	md->tag_set->driver_data = md;
+
+	md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
+	immutable_tgt = dm_table_get_immutable_target(t);
+	if (immutable_tgt && immutable_tgt->per_io_data_size) {
+		/* any target-specific per-io data is immediately after the tio */
+		md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
+		md->init_tio_pdu = true;
+	}
+
+	err = blk_mq_alloc_tag_set(md->tag_set);
+	if (err)
+		goto out_kfree_tag_set;
+
+	q = blk_mq_init_allocated_queue(md->tag_set, md->queue);
+	if (IS_ERR(q)) {
+		err = PTR_ERR(q);
+		goto out_tag_set;
+	}
+	dm_init_md_queue(md);
+
+	/* backfill 'mq' sysfs registration normally done in blk_register_queue */
+	blk_mq_register_disk(md->disk);
+
+	return 0;
+
+out_tag_set:
+	blk_mq_free_tag_set(md->tag_set);
+out_kfree_tag_set:
+	kfree(md->tag_set);
+
+	return err;
+}
+
+void dm_mq_cleanup_mapped_device(struct mapped_device *md)
+{
+	if (md->tag_set) {
+		blk_mq_free_tag_set(md->tag_set);
+		kfree(md->tag_set);
+	}
+}
+
+module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
+
+module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
+
+module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
+
+module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");

drivers/md/dm-rq.h

···
+/*
+ * Internal header file for device mapper
+ *
+ * Copyright (C) 2016 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the LGPL.
+ */
+
+#ifndef DM_RQ_INTERNAL_H
+#define DM_RQ_INTERNAL_H
+
+#include <linux/bio.h>
+#include <linux/kthread.h>
+
+#include "dm-stats.h"
+
+struct mapped_device;
+
+/*
+ * One of these is allocated per request.
+ */
+struct dm_rq_target_io {
+	struct mapped_device *md;
+	struct dm_target *ti;
+	struct request *orig, *clone;
+	struct kthread_work work;
+	int error;
+	union map_info info;
+	struct dm_stats_aux stats_aux;
+	unsigned long duration_jiffies;
+	unsigned n_sectors;
+};
+
+/*
+ * For request-based dm - the bio clones we allocate are embedded in these
+ * structs.
+ *
+ * We allocate these with bio_alloc_bioset, using the front_pad parameter when
+ * the bioset is created - this means the bio has to come at the end of the
+ * struct.
+ */
+struct dm_rq_clone_bio_info {
+	struct bio *orig;
+	struct dm_rq_target_io *tio;
+	struct bio clone;
+};
+
+bool dm_use_blk_mq_default(void);
+bool dm_use_blk_mq(struct mapped_device *md);
+
+int dm_old_init_request_queue(struct mapped_device *md);
+int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t);
+void dm_mq_cleanup_mapped_device(struct mapped_device *md);
+
+void dm_start_queue(struct request_queue *q);
+void dm_stop_queue(struct request_queue *q);
+
+unsigned dm_get_reserved_rq_based_ios(void);
+
+ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf);
+ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
+						     const char *buf, size_t count);
+
+#endif

drivers/md/dm-snap.c

···
 	return do_origin(o->dev, bio);
 }
 
+static long origin_direct_access(struct dm_target *ti, sector_t sector,
+		void __pmem **kaddr, pfn_t *pfn, long size)
+{
+	DMWARN("device does not support dax.");
+	return -EIO;
+}
+
 /*
  * Set the target "max_io_len" field to the minimum of all the snapshots'
  * chunk sizes.
···
 	.postsuspend = origin_postsuspend,
 	.status  = origin_status,
 	.iterate_devices = origin_iterate_devices,
+	.direct_access = origin_direct_access,
 };
 
 static struct target_type snapshot_target = {

drivers/md/dm-stats.c

···
 #include <linux/module.h>
 #include <linux/device-mapper.h>
 
-#include "dm.h"
+#include "dm-core.h"
 #include "dm-stats.h"
 
 #define DM_MSG_PREFIX "stats"

drivers/md/dm-stripe.c

···
 	return DM_MAPIO_REMAPPED;
 }
 
+static long stripe_direct_access(struct dm_target *ti, sector_t sector,
+				 void __pmem **kaddr, pfn_t *pfn, long size)
+{
+	struct stripe_c *sc = ti->private;
+	uint32_t stripe;
+	struct block_device *bdev;
+	struct blk_dax_ctl dax = {
+		.size = size,
+	};
+	long ret;
+
+	stripe_map_sector(sc, sector, &stripe, &dax.sector);
+
+	dax.sector += sc->stripe[stripe].physical_start;
+	bdev = sc->stripe[stripe].dev->bdev;
+
+	ret = bdev_direct_access(bdev, &dax);
+	*kaddr = dax.addr;
+	*pfn = dax.pfn;
+
+	return ret;
+}
+
 /*
  * Stripe status:
  *
···
 
 static struct target_type stripe_target = {
 	.name   = "striped",
-	.version = {1, 5, 1},
+	.version = {1, 6, 0},
 	.module = THIS_MODULE,
 	.ctr    = stripe_ctr,
 	.dtr    = stripe_dtr,
···
 	.status = stripe_status,
 	.iterate_devices = stripe_iterate_devices,
 	.io_hints = stripe_io_hints,
+	.direct_access = stripe_direct_access,
 };
 
 int __init dm_stripe_init(void)

drivers/md/dm-sysfs.c

···
 
 #include <linux/sysfs.h>
 #include <linux/dm-ioctl.h>
-#include "dm.h"
+#include "dm-core.h"
+#include "dm-rq.h"
 
 struct dm_sysfs_attr {
 	struct attribute attr;

drivers/md/dm-table.c

···
  * This file is released under the GPL.
  */
 
-#include "dm.h"
+#include "dm-core.h"
 
 #include <linux/module.h>
 #include <linux/vmalloc.h>
···
 	struct dm_target *targets;
 
 	struct target_type *immutable_target_type;
-	unsigned integrity_supported:1;
-	unsigned singleton:1;
+
+	bool integrity_supported:1;
+	bool singleton:1;
+	bool all_blk_mq:1;
 
 	/*
 	 * Indicates the rw permissions for the new logical
···
 		return -ENOMEM;
 	}
 
+	t->type = DM_TYPE_NONE;
 	t->mode = mode;
 	t->md = md;
 	*result = t;
···
 			      dm_device_name(t->md), type);
 			return -EINVAL;
 		}
-		t->singleton = 1;
+		t->singleton = true;
 	}
 
 	if (dm_target_always_writeable(tgt->type) && !(t->mode & FMODE_WRITE)) {
···
 }
 EXPORT_SYMBOL(dm_consume_args);
 
+static bool __table_type_bio_based(unsigned table_type)
+{
+	return (table_type == DM_TYPE_BIO_BASED ||
+		table_type == DM_TYPE_DAX_BIO_BASED);
+}
+
 static bool __table_type_request_based(unsigned table_type)
 {
 	return (table_type == DM_TYPE_REQUEST_BASED ||
 		table_type == DM_TYPE_MQ_REQUEST_BASED);
 }
 
-static int dm_table_set_type(struct dm_table *t)
+void dm_table_set_type(struct dm_table *t, unsigned type)
+{
+	t->type = type;
+}
+EXPORT_SYMBOL_GPL(dm_table_set_type);
+
+static int device_supports_dax(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);
+
+	return q && blk_queue_dax(q);
+}
+
+static bool dm_table_supports_dax(struct dm_table *t)
+{
+	struct dm_target *ti;
+	unsigned i = 0;
+
+	/* Ensure that all targets support DAX. */
+	while (i < dm_table_get_num_targets(t)) {
+		ti = dm_table_get_target(t, i++);
+
+		if (!ti->type->direct_access)
+			return false;
+
+		if (!ti->type->iterate_devices ||
+		    !ti->type->iterate_devices(ti, device_supports_dax, NULL))
+			return false;
+	}
+
+	return true;
+}
+
+static int dm_table_determine_type(struct dm_table *t)
 {
 	unsigned i;
 	unsigned bio_based = 0, request_based = 0, hybrid = 0;
-	bool use_blk_mq = false;
+	bool verify_blk_mq = false;
 	struct dm_target *tgt;
 	struct dm_dev_internal *dd;
-	struct list_head *devices;
+	struct list_head *devices = dm_table_get_devices(t);
 	unsigned live_md_type = dm_get_md_type(t->md);
+
+	if (t->type != DM_TYPE_NONE) {
+		/* target already set the table's type */
+		if (t->type == DM_TYPE_BIO_BASED)
+			return 0;
+		BUG_ON(t->type == DM_TYPE_DAX_BIO_BASED);
+		goto verify_rq_based;
+	}
 
 	for (i = 0; i < t->num_targets; i++) {
 		tgt = t->targets + i;
···
 	if (bio_based) {
 		/* 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))
+			t->type = DM_TYPE_DAX_BIO_BASED;
 		return 0;
 	}
 
 	BUG_ON(!request_based); /* No targets in this table */
 
+	if (list_empty(devices) && __table_type_request_based(live_md_type)) {
+		/* inherit live MD type */
+		t->type = live_md_type;
+		return 0;
+	}
+
+	/*
+	 * The only way to establish DM_TYPE_MQ_REQUEST_BASED is by
+	 * having a compatible target use dm_table_set_type.
+	 */
+	t->type = DM_TYPE_REQUEST_BASED;
+
+verify_rq_based:
 	/*
 	 * Request-based dm supports only tables that have a single target now.
 	 * To support multiple targets, request splitting support is needed,
···
 	}
 
 	/* Non-request-stackable devices can't be used for request-based dm */
-	devices = dm_table_get_devices(t);
 	list_for_each_entry(dd, devices, list) {
 		struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
 
···
 		}
 
 		if (q->mq_ops)
-			use_blk_mq = true;
+			verify_blk_mq = true;
 	}
 
-	if (use_blk_mq) {
+	if (verify_blk_mq) {
 		/* verify _all_ devices in the table are blk-mq devices */
 		list_for_each_entry(dd, devices, list)
 			if (!bdev_get_queue(dd->dm_dev->bdev)->mq_ops) {
···
 				      " are blk-mq request-stackable");
 				return -EINVAL;
 			}
-		t->type = DM_TYPE_MQ_REQUEST_BASED;
 
-	} else if (list_empty(devices) && __table_type_request_based(live_md_type)) {
-		/* inherit live MD type */
-		t->type = live_md_type;
-
-	} else
-		t->type = DM_TYPE_REQUEST_BASED;
+		t->all_blk_mq = true;
+	}
 
 	return 0;
 }
···
 	return NULL;
 }
 
+bool dm_table_bio_based(struct dm_table *t)
+{
+	return __table_type_bio_based(dm_table_get_type(t));
+}
+
 bool dm_table_request_based(struct dm_table *t)
 {
 	return __table_type_request_based(dm_table_get_type(t));
 }
 
-bool dm_table_mq_request_based(struct dm_table *t)
+bool dm_table_all_blk_mq_devices(struct dm_table *t)
 {
-	return dm_table_get_type(t) == DM_TYPE_MQ_REQUEST_BASED;
+	return t->all_blk_mq;
 }
 
 static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *md)
···
 		return -EINVAL;
 	}
 
-	if (type == DM_TYPE_BIO_BASED)
+	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);
···
 		return 0;
 
 	if (!integrity_profile_exists(dm_disk(md))) {
-		t->integrity_supported = 1;
+		t->integrity_supported = true;
 		/*
 		 * Register integrity profile during table load; we can do
 		 * this because the final profile must match during resume.
···
 	}
 
 	/* Preserve existing integrity profile */
-	t->integrity_supported = 1;
+	t->integrity_supported = true;
 	return 0;
 }
 
···
 {
 	int r;
 
-	r = dm_table_set_type(t);
+	r = dm_table_determine_type(t);
 	if (r) {
-		DMERR("unable to set table type");
+		DMERR("unable to determine table type");
 		return r;
 	}
 

drivers/md/dm-target.c

···
  * This file is released under the GPL.
  */
 
-#include "dm.h"
+#include "dm-core.h"
 
 #include <linux/module.h>
 #include <linux/init.h>
···
 {
 }
 
+static long io_err_direct_access(struct dm_target *ti, sector_t sector,
+				 void __pmem **kaddr, pfn_t *pfn, long size)
+{
+	return -EIO;
+}
+
 static struct target_type error_target = {
 	.name = "error",
-	.version = {1, 4, 0},
+	.version = {1, 5, 0},
 	.features = DM_TARGET_WILDCARD,
 	.ctr  = io_err_ctr,
 	.dtr  = io_err_dtr,
···
 	.map_rq = io_err_map_rq,
 	.clone_and_map_rq = io_err_clone_and_map_rq,
 	.release_clone_rq = io_err_release_clone_rq,
+	.direct_access = io_err_direct_access,
 };
 
 int __init dm_target_init(void)

drivers/md/dm-thin-metadata.c

···
 	return r;
 }
 
+int dm_pool_inc_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e)
+{
+	int r = 0;
+
+	down_write(&pmd->root_lock);
+	for (; b != e; b++) {
+		r = dm_sm_inc_block(pmd->data_sm, b);
+		if (r)
+			break;
+	}
+	up_write(&pmd->root_lock);
+
+	return r;
+}
+
+int dm_pool_dec_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e)
+{
+	int r = 0;
+
+	down_write(&pmd->root_lock);
+	for (; b != e; b++) {
+		r = dm_sm_dec_block(pmd->data_sm, b);
+		if (r)
+			break;
+	}
+	up_write(&pmd->root_lock);
+
+	return r;
+}
+
 bool dm_thin_changed_this_transaction(struct dm_thin_device *td)
 {
 	int r;

drivers/md/dm-thin-metadata.h

···
 
 int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result);
 
+int dm_pool_inc_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e);
+int dm_pool_dec_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e);
+
 /*
  * Returns -ENOSPC if the new size is too small and already allocated
  * blocks would be lost.

drivers/md/dm-thin.c

···
 	struct bio_list deferred_flush_bios;
 	struct list_head prepared_mappings;
 	struct list_head prepared_discards;
+	struct list_head prepared_discards_pt2;
 	struct list_head active_thins;
 
 	struct dm_deferred_set *shared_read_ds;
···
 
 	process_mapping_fn process_prepared_mapping;
 	process_mapping_fn process_prepared_discard;
+	process_mapping_fn process_prepared_discard_pt2;
 
 	struct dm_bio_prison_cell **cell_sort_array;
 };
···
 
 /*----------------------------------------------------------------*/
 
-static void passdown_double_checking_shared_status(struct dm_thin_new_mapping *m)
+static void passdown_double_checking_shared_status(struct dm_thin_new_mapping *m,
+						   struct bio *discard_parent)
 {
 	/*
 	 * We've already unmapped this range of blocks, but before we
···
 	dm_block_t b = m->data_block, e, end = m->data_block + m->virt_end - m->virt_begin;
 	struct discard_op op;
 
-	begin_discard(&op, tc, m->bio);
+	begin_discard(&op, tc, discard_parent);
 	while (b != end) {
 		/* find start of unmapped run */
 		for (; b < end; b++) {
···
 	end_discard(&op, r);
 }
 
-static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m)
+static void queue_passdown_pt2(struct dm_thin_new_mapping *m)
+{
+	unsigned long flags;
+	struct pool *pool = m->tc->pool;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	list_add_tail(&m->list, &pool->prepared_discards_pt2);
+	spin_unlock_irqrestore(&pool->lock, flags);
+	wake_worker(pool);
+}
+
+static void passdown_endio(struct bio *bio)
+{
+	/*
+	 * It doesn't matter if the passdown discard failed, we still want
+	 * to unmap (we ignore err).
+	 */
+	queue_passdown_pt2(bio->bi_private);
+}
+
+static void process_prepared_discard_passdown_pt1(struct dm_thin_new_mapping *m)
+{
+	int r;
+	struct thin_c *tc = m->tc;
+	struct pool *pool = tc->pool;
+	struct bio *discard_parent;
+	dm_block_t data_end = m->data_block + (m->virt_end - m->virt_begin);
+
+	/*
+	 * Only this thread allocates blocks, so we can be sure that the
+	 * newly unmapped blocks will not be allocated before the end of
+	 * the function.
+	 */
+	r = dm_thin_remove_range(tc->td, m->virt_begin, m->virt_end);
+	if (r) {
+		metadata_operation_failed(pool, "dm_thin_remove_range", r);
+		bio_io_error(m->bio);
+		cell_defer_no_holder(tc, m->cell);
+		mempool_free(m, pool->mapping_pool);
+		return;
+	}
+
+	discard_parent = bio_alloc(GFP_NOIO, 1);
+	if (!discard_parent) {
+		DMWARN("%s: unable to allocate top level discard bio for passdown. Skipping passdown.",
+		       dm_device_name(tc->pool->pool_md));
+		queue_passdown_pt2(m);
+
+	} else {
+		discard_parent->bi_end_io = passdown_endio;
+		discard_parent->bi_private = m;
+
+		if (m->maybe_shared)
+			passdown_double_checking_shared_status(m, discard_parent);
+		else {
+			struct discard_op op;
+
+			begin_discard(&op, tc, discard_parent);
+			r = issue_discard(&op, m->data_block, data_end);
+			end_discard(&op, r);
+		}
+	}
+
+	/*
+	 * Increment the unmapped blocks.  This prevents a race between the
+	 * passdown io and reallocation of freed blocks.
+	 */
+	r = dm_pool_inc_data_range(pool->pmd, m->data_block, data_end);
+	if (r) {
+		metadata_operation_failed(pool, "dm_pool_inc_data_range", r);
+		bio_io_error(m->bio);
+		cell_defer_no_holder(tc, m->cell);
+		mempool_free(m, pool->mapping_pool);
+		return;
+	}
+}
+
+static void process_prepared_discard_passdown_pt2(struct dm_thin_new_mapping *m)
 {
 	int r;
 	struct thin_c *tc = m->tc;
 	struct pool *pool = tc->pool;
 
-	r = dm_thin_remove_range(tc->td, m->virt_begin, m->virt_end);
+	/*
+	 * The passdown has completed, so now we can decrement all those
+	 * unmapped blocks.
+	 */
+	r = dm_pool_dec_data_range(pool->pmd, m->data_block,
+				   m->data_block + (m->virt_end - m->virt_begin));
 	if (r) {
-		metadata_operation_failed(pool, "dm_thin_remove_range", r);
+		metadata_operation_failed(pool, "dm_pool_dec_data_range", r);
 		bio_io_error(m->bio);
-
-	} else if (m->maybe_shared) {
-		passdown_double_checking_shared_status(m);
-
-	} else {
-		struct discard_op op;
-		begin_discard(&op, tc, m->bio);
-		r = issue_discard(&op, m->data_block,
-				  m->data_block + (m->virt_end - m->virt_begin));
-		end_discard(&op, r);
-	}
+	} else
+		bio_endio(m->bio);
 
 	cell_defer_no_holder(tc, m->cell);
 	mempool_free(m, pool->mapping_pool);
···
 	throttle_work_update(&pool->throttle);
 	process_prepared(pool, &pool->prepared_discards, &pool->process_prepared_discard);
 	throttle_work_update(&pool->throttle);
+	process_prepared(pool, &pool->prepared_discards_pt2, &pool->process_prepared_discard_pt2);
+	throttle_work_update(&pool->throttle);
 	process_deferred_bios(pool);
 	throttle_work_complete(&pool->throttle);
 }
···
 
 	if (passdown_enabled(pt)) {
 		pool->process_discard_cell = process_discard_cell_passdown;
-		pool->process_prepared_discard = process_prepared_discard_passdown;
+		pool->process_prepared_discard = process_prepared_discard_passdown_pt1;
+		pool->process_prepared_discard_pt2 = process_prepared_discard_passdown_pt2;
 	} else {
 		pool->process_discard_cell = process_discard_cell_no_passdown;
 		pool->process_prepared_discard = process_prepared_discard_no_passdown;
···
 	bio_list_init(&pool->deferred_flush_bios);
 	INIT_LIST_HEAD(&pool->prepared_mappings);
 	INIT_LIST_HEAD(&pool->prepared_discards);
+	INIT_LIST_HEAD(&pool->prepared_discards_pt2);
 	INIT_LIST_HEAD(&pool->active_thins);
 	pool->low_water_triggered = false;
 	pool->suspended = true;

drivers/md/dm-verity-fec.c

···
 	 */
 
 	offset = block << v->data_dev_block_bits;
-
-	res = offset;
-	div64_u64(res, v->fec->rounds << v->data_dev_block_bits);
+	res = div64_u64(offset, v->fec->rounds << v->data_dev_block_bits);
 
 	/*
 	 * The base RS block we can feed to the interleaver to find out all

drivers/md/dm.c

···
  * This file is released under the GPL.
  */
 
-#include "dm.h"
+#include "dm-core.h"
+#include "dm-rq.h"
 #include "dm-uevent.h"
 
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
-#include <linux/moduleparam.h>
 #include <linux/blkpg.h>
 #include <linux/bio.h>
 #include <linux/mempool.h>
···
 #include <linux/hdreg.h>
 #include <linux/delay.h>
 #include <linux/wait.h>
-#include <linux/kthread.h>
-#include <linux/ktime.h>
-#include <linux/elevator.h> /* for rq_end_sector() */
-#include <linux/blk-mq.h>
 #include <linux/pr.h>
-
-#include <trace/events/block.h>
 
 #define DM_MSG_PREFIX "core"
 
···
 static struct workqueue_struct *deferred_remove_workqueue;
 
 /*
- * For bio-based dm.
  * One of these is allocated per bio.
  */
 struct dm_io {
···
 	unsigned long start_time;
 	spinlock_t endio_lock;
 	struct dm_stats_aux stats_aux;
-};
-
-/*
- * For request-based dm.
- * One of these is allocated per request.
- */
-struct dm_rq_target_io {
-	struct mapped_device *md;
-	struct dm_target *ti;
-	struct request *orig, *clone;
-	struct kthread_work work;
-	int error;
-	union map_info info;
-	struct dm_stats_aux stats_aux;
-	unsigned long duration_jiffies;
-	unsigned n_sectors;
-};
-
-/*
- * For request-based dm - the bio clones we allocate are embedded in these
- * structs.
- *
- * We allocate these with bio_alloc_bioset, using the front_pad parameter when
- * the bioset is created - this means the bio has to come at the end of the
- * struct.
- */
-struct dm_rq_clone_bio_info {
-	struct bio *orig;
-	struct dm_rq_target_io *tio;
-	struct bio clone;
 };
 
 #define MINOR_ALLOCED ((void *)-1)
···
 #define DMF_DEFERRED_REMOVE 6
 #define DMF_SUSPENDED_INTERNALLY 7
 
-/*
- * Work processed by per-device workqueue.
- */
-struct mapped_device {
-	struct srcu_struct io_barrier;
-	struct mutex suspend_lock;
-
-	/*
-	 * The current mapping (struct dm_table *).
-	 * Use dm_get_live_table{_fast} or take suspend_lock for
-	 * dereference.
-	 */
-	void __rcu *map;
-
-	struct list_head table_devices;
-	struct mutex table_devices_lock;
-
-	unsigned long flags;
-
-	struct request_queue *queue;
-	int numa_node_id;
-
-	unsigned type;
-	/* Protect queue and type against concurrent access. */
-	struct mutex type_lock;
-
-	atomic_t holders;
-	atomic_t open_count;
-
-	struct dm_target *immutable_target;
-	struct target_type *immutable_target_type;
-
-	struct gendisk *disk;
-	char name[16];
-
-	void *interface_ptr;
-
-	/*
-	 * A list of ios that arrived while we were suspended.
-	 */
-	atomic_t pending[2];
-	wait_queue_head_t wait;
-	struct work_struct work;
-	spinlock_t deferred_lock;
-	struct bio_list deferred;
-
-	/*
-	 * Event handling.
-	 */
-	wait_queue_head_t eventq;
-	atomic_t event_nr;
-	atomic_t uevent_seq;
-	struct list_head uevent_list;
-	spinlock_t uevent_lock; /* Protect access to uevent_list */
-
-	/* the number of internal suspends */
-	unsigned internal_suspend_count;
-
-	/*
-	 * Processing queue (flush)
-	 */
-	struct workqueue_struct *wq;
-
-	/*
-	 * io objects are allocated from here.
-	 */
-	mempool_t *io_pool;
-	mempool_t *rq_pool;
-
-	struct bio_set *bs;
-
-	/*
-	 * freeze/thaw support require holding onto a super block
-	 */
-	struct super_block *frozen_sb;
-
-	/* forced geometry settings */
-	struct hd_geometry geometry;
-
-	struct block_device *bdev;
-
-	/* kobject and completion */
-	struct dm_kobject_holder kobj_holder;
-
-	/* zero-length flush that will be cloned and submitted to targets */
-	struct bio flush_bio;
-
-	struct dm_stats stats;
-
-	struct kthread_worker kworker;
-	struct task_struct *kworker_task;
-
-	/* for request-based merge heuristic in dm_request_fn() */
-	unsigned seq_rq_merge_deadline_usecs;
-	int last_rq_rw;
-	sector_t last_rq_pos;
-	ktime_t last_rq_start_time;
-
-	/* for blk-mq request-based DM support */
-	struct blk_mq_tag_set *tag_set;
-	bool use_blk_mq:1;
-	bool init_tio_pdu:1;
-};
-
-#ifdef CONFIG_DM_MQ_DEFAULT
-static bool use_blk_mq = true;
-#else
-static bool use_blk_mq = false;
-#endif
-
-#define DM_MQ_NR_HW_QUEUES 1
-#define DM_MQ_QUEUE_DEPTH 2048
 #define DM_NUMA_NODE NUMA_NO_NODE
-
-static unsigned dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES;
-static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;
 static int dm_numa_node = DM_NUMA_NODE;
-
-bool dm_use_blk_mq(struct mapped_device *md)
-{
-	return md->use_blk_mq;
-}
-EXPORT_SYMBOL_GPL(dm_use_blk_mq);
 
 /*
  * For mempools pre-allocation at the table loading time.
···
 	struct dm_dev dm_dev;
 };
 
-#define RESERVED_BIO_BASED_IOS		16
-#define RESERVED_REQUEST_BASED_IOS	256
-#define RESERVED_MAX_IOS		1024
 static struct kmem_cache *_io_cache;
 static struct kmem_cache *_rq_tio_cache;
 static struct kmem_cache *_rq_cache;
···
 /*
  * Bio-based DM's mempools' reserved IOs set by the user.
  */
+#define RESERVED_BIO_BASED_IOS		16
 static unsigned reserved_bio_based_ios = RESERVED_BIO_BASED_IOS;
-
-/*
- * Request-based DM's mempools' reserved IOs set by the user.
- */
-static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
 
 static int __dm_get_module_param_int(int *module_param, int min, int max)
 {
···
 	return param;
 }
 
-static unsigned __dm_get_module_param(unsigned *module_param,
-				      unsigned def, unsigned max)
+unsigned __dm_get_module_param(unsigned *module_param,
+			       unsigned def, unsigned max)
 {
 	unsigned param = ACCESS_ONCE(*module_param);
 	unsigned modified_param = 0;
···
 unsigned dm_get_reserved_bio_based_ios(void)
 {
 	return __dm_get_module_param(&reserved_bio_based_ios,
-				     RESERVED_BIO_BASED_IOS, RESERVED_MAX_IOS);
+				     RESERVED_BIO_BASED_IOS, DM_RESERVED_MAX_IOS);
 }
 EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios);
-
-unsigned dm_get_reserved_rq_based_ios(void)
-{
-	return __dm_get_module_param(&reserved_rq_based_ios,
-				     RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS);
-}
-EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
-
-static unsigned dm_get_blk_mq_nr_hw_queues(void)
-{
-	return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32);
-}
-
-static unsigned dm_get_blk_mq_queue_depth(void)
-{
-	return __dm_get_module_param(&dm_mq_queue_depth,
-				     DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);
-}
 
 static unsigned dm_get_numa_node(void)
 {
···
 	bio_put(&tio->clone);
 }
 
-static struct dm_rq_target_io *alloc_old_rq_tio(struct mapped_device *md,
-						gfp_t gfp_mask)
-{
-	return mempool_alloc(md->io_pool, gfp_mask);
-}
-
-static void free_old_rq_tio(struct dm_rq_target_io *tio)
-{
-	mempool_free(tio, tio->md->io_pool);
-}
-
-static struct request *alloc_old_clone_request(struct mapped_device *md,
-					       gfp_t gfp_mask)
-{
-	return mempool_alloc(md->rq_pool, gfp_mask);
-}
-
-static void free_old_clone_request(struct mapped_device *md, struct request *rq)
-{
-	mempool_free(rq, md->rq_pool);
-}
-
-static int md_in_flight(struct mapped_device *md)
+int md_in_flight(struct mapped_device *md)
 {
 	return atomic_read(&md->pending[READ]) +
 	       atomic_read(&md->pending[WRITE]);
···
 	}
 }
 
-static void disable_write_same(struct mapped_device *md)
+void disable_write_same(struct mapped_device *md)
 {
 	struct queue_limits *limits = dm_get_queue_limits(md);
 
···
 
 	free_tio(tio);
 	dec_pending(io, error);
-}
-
-/*
- * Partial completion handling for request-based dm
- */
-static void end_clone_bio(struct bio *clone)
-{
-	struct dm_rq_clone_bio_info *info =
-		container_of(clone, struct dm_rq_clone_bio_info, clone);
-	struct dm_rq_target_io *tio = info->tio;
-	struct bio *bio = info->orig;
-	unsigned int nr_bytes = info->orig->bi_iter.bi_size;
-	int error = clone->bi_error;
-
-	bio_put(clone);
-
-	if (tio->error)
-		/*
-		 * An error has already been detected on the request.
-		 * Once error occurred, just let clone->end_io() handle
-		 * the remainder.
-		 */
-		return;
-	else if (error) {
-		/*
-		 * Don't notice the error to the upper layer yet.
-		 * The error handling decision is made by the target driver,
-		 * when the request is completed.
-		 */
-		tio->error = error;
-		return;
-	}
-
-	/*
-	 * I/O for the bio successfully completed.
-	 * Notice the data completion to the upper layer.
-	 */
-
-	/*
-	 * bios are processed from the head of the list.
-	 * So the completing bio should always be rq->bio.
-	 * If it's not, something wrong is happening.
-	 */
-	if (tio->orig->bio != bio)
-		DMERR("bio completion is going in the middle of the request");
-
-	/*
-	 * Update the original request.
-	 * Do not use blk_end_request() here, because it may complete
-	 * the original request before the clone, and break the ordering.
-	 */
-	blk_update_request(tio->orig, 0, nr_bytes);
-}
-
-static struct dm_rq_target_io *tio_from_request(struct request *rq)
-{
-	return (rq->q->mq_ops ? blk_mq_rq_to_pdu(rq) : rq->special);
-}
-
-static void rq_end_stats(struct mapped_device *md, struct request *orig)
-{
-	if (unlikely(dm_stats_used(&md->stats))) {
-		struct dm_rq_target_io *tio = tio_from_request(orig);
-		tio->duration_jiffies = jiffies - tio->duration_jiffies;
-		dm_stats_account_io(&md->stats, rq_data_dir(orig),
-				    blk_rq_pos(orig), tio->n_sectors, true,
-				    tio->duration_jiffies, &tio->stats_aux);
-	}
-}
-
-/*
- * Don't touch any member of the md after calling this function because
- * the md may be freed in dm_put() at the end of this function.
- * Or do dm_get() before calling this function and dm_put() later.
- */
-static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
-{
-	atomic_dec(&md->pending[rw]);
-
-	/* nudge anyone waiting on suspend queue */
-	if (!md_in_flight(md))
-		wake_up(&md->wait);
-
-	/*
-	 * Run this off this callpath, as drivers could invoke end_io while
-	 * inside their request_fn (and holding the queue lock). Calling
-	 * back into ->request_fn() could deadlock attempting to grab the
-	 * queue lock again.
-	 */
-	if (!md->queue->mq_ops && run_queue)
-		blk_run_queue_async(md->queue);
-
-	/*
-	 * dm_put() must be at the end of this function. See the comment above
-	 */
-	dm_put(md);
-}
-
-static void free_rq_clone(struct request *clone)
-{
-	struct dm_rq_target_io *tio = clone->end_io_data;
-	struct mapped_device *md = tio->md;
-
-	blk_rq_unprep_clone(clone);
-
-	if (md->type == DM_TYPE_MQ_REQUEST_BASED)
-		/* stacked on blk-mq queue(s) */
-		tio->ti->type->release_clone_rq(clone);
-	else if (!md->queue->mq_ops)
-		/* request_fn queue stacked on request_fn queue(s) */
-		free_old_clone_request(md, clone);
-
-	if (!md->queue->mq_ops)
-		free_old_rq_tio(tio);
-}
-
-/*
- * Complete the clone and the original request.
- * Must be called without clone's queue lock held,
- * see end_clone_request() for more details.
- */
-static void dm_end_request(struct request *clone, int error)
-{
-	int rw = rq_data_dir(clone);
-	struct dm_rq_target_io *tio = clone->end_io_data;
-	struct mapped_device *md = tio->md;
-	struct request *rq = tio->orig;
-
-	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
-		rq->errors = clone->errors;
-		rq->resid_len = clone->resid_len;
-
-		if (rq->sense)
-			/*
-			 * We are using the sense buffer of the original
-			 * request.
-			 * So setting the length of the sense data is enough.
-			 */
-			rq->sense_len = clone->sense_len;
-	}
-
-	free_rq_clone(clone);
-	rq_end_stats(md, rq);
-	if (!rq->q->mq_ops)
-		blk_end_request_all(rq, error);
-	else
-		blk_mq_end_request(rq, error);
-	rq_completed(md, rw, true);
-}
-
-static void dm_unprep_request(struct request *rq)
-{
-	struct dm_rq_target_io *tio = tio_from_request(rq);
-	struct request *clone = tio->clone;
-
-	if (!rq->q->mq_ops) {
-		rq->special = NULL;
-		rq->cmd_flags &= ~REQ_DONTPREP;
-	}
-
-	if (clone)
-		free_rq_clone(clone);
-	else if (!tio->md->queue->mq_ops)
-		free_old_rq_tio(tio);
-}
-
-/*
- * Requeue the original request of a clone.
- */
-static void dm_old_requeue_request(struct request *rq)
-{
-	struct request_queue *q = rq->q;
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	blk_requeue_request(q, rq);
-	blk_run_queue_async(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-static void dm_mq_requeue_request(struct request *rq)
-{
-	struct request_queue *q = rq->q;
-	unsigned long flags;
-
-	blk_mq_requeue_request(rq);
-	spin_lock_irqsave(q->queue_lock, flags);
-	if (!blk_queue_stopped(q))
-		blk_mq_kick_requeue_list(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-static void dm_requeue_original_request(struct mapped_device *md,
-					struct request *rq)
-{
-	int rw = rq_data_dir(rq);
-
-	rq_end_stats(md, rq);
-	dm_unprep_request(rq);
-
-	if (!rq->q->mq_ops)
-		dm_old_requeue_request(rq);
-	else
-		dm_mq_requeue_request(rq);
-
-	rq_completed(md, rw, false);
-}
-
-static void dm_old_stop_queue(struct request_queue *q)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	if (blk_queue_stopped(q)) {
-		spin_unlock_irqrestore(q->queue_lock, flags);
-		return;
-	}
-
-	blk_stop_queue(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-static void dm_stop_queue(struct request_queue *q)
-{
-	if (!q->mq_ops)
-		dm_old_stop_queue(q);
-	else
-		blk_mq_stop_hw_queues(q);
-}
-
-static void dm_old_start_queue(struct request_queue *q)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	if (blk_queue_stopped(q))
-		blk_start_queue(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-static void dm_start_queue(struct request_queue *q)
-{
-	if (!q->mq_ops)
-		dm_old_start_queue(q);
-	else {
-		blk_mq_start_stopped_hw_queues(q, true);
-		blk_mq_kick_requeue_list(q);
-	}
-}
-
-static void dm_done(struct request *clone, int error, bool mapped)
-{
-	int r = error;
-	struct dm_rq_target_io *tio = clone->end_io_data;
-	dm_request_endio_fn rq_end_io = NULL;
-
-	if (tio->ti) {
-		rq_end_io = tio->ti->type->rq_end_io;
-
-		if (mapped && rq_end_io)
-			r = rq_end_io(tio->ti, clone, error, &tio->info);
-	}
-
-	if (unlikely(r == -EREMOTEIO && (req_op(clone) == REQ_OP_WRITE_SAME) &&
-		     !clone->q->limits.max_write_same_sectors))
-		disable_write_same(tio->md);
-
-	if (r <= 0)
-		/* The target wants to complete the I/O */
-		dm_end_request(clone, r);
-	else if (r == DM_ENDIO_INCOMPLETE)
-		/* The target will handle the I/O */
-		return;
-	else if (r == DM_ENDIO_REQUEUE)
-		/* The target wants to requeue the I/O */
-		dm_requeue_original_request(tio->md, tio->orig);
-	else {
-		DMWARN("unimplemented target endio return value: %d", r);
-		BUG();
-	}
-}
-
-/*
- * Request completion handler for request-based dm
- */
-static void dm_softirq_done(struct request *rq)
-{
-	bool mapped = true;
-	struct dm_rq_target_io *tio = tio_from_request(rq);
-	struct request *clone = tio->clone;
-	int rw;
-
-	if (!clone) {
-		rq_end_stats(tio->md, rq);
-		rw = rq_data_dir(rq);
-		if (!rq->q->mq_ops) {
-			blk_end_request_all(rq, tio->error);
-			rq_completed(tio->md, rw, false);
-			free_old_rq_tio(tio);
-		} else {
-			blk_mq_end_request(rq, tio->error);
-			rq_completed(tio->md, rw, false);
-		}
-		return;
-	}
-
-	if (rq->cmd_flags & REQ_FAILED)
-		mapped = false;
-
-	dm_done(clone, tio->error, mapped);
-}
-
-/*
- * Complete the clone and the original request with the error status
- * through softirq context.
- */
-static void dm_complete_request(struct request *rq, int error)
-{
-	struct dm_rq_target_io *tio = tio_from_request(rq);
-
-	tio->error = error;
-	if (!rq->q->mq_ops)
-		blk_complete_request(rq);
-	else
-		blk_mq_complete_request(rq, error);
-}
-
-/*
- * Complete the not-mapped clone and the original request with the error status
- * through softirq context.
- * Target's rq_end_io() function isn't called.
- * This may be used when the target's map_rq() or clone_and_map_rq() functions fail.
- */
-static void dm_kill_unmapped_request(struct request *rq, int error)
-{
-	rq->cmd_flags |= REQ_FAILED;
-	dm_complete_request(rq, error);
-}
-
-/*
- * Called with the clone's queue lock held (in the case of .request_fn)
- */
-static void end_clone_request(struct request *clone, int error)
-{
-	struct dm_rq_target_io *tio = clone->end_io_data;
-
-	if (!clone->q->mq_ops) {
-		/*
-		 * For just cleaning up the information of the queue in which
-		 * the clone was dispatched.
-		 * The clone is *NOT* freed actually here because it is alloced
-		 * from dm own mempool (REQ_ALLOCED isn't set).
-		 */
-		__blk_put_request(clone->q, clone);
-	}
-
-	/*
-	 * Actual request completion is done in a softirq context which doesn't
-	 * hold the clone's queue lock.  Otherwise, deadlock could occur because:
-	 *     - another request may be submitted by the upper level driver
-	 *       of the stacking during the completion
-	 *     - the submission which requires queue lock may be done
-	 *       against this clone's queue
-	 */
-	dm_complete_request(tio->orig, error);
 }
 
 /*
···
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
+
+static long dm_blk_direct_access(struct block_device *bdev, sector_t sector,
+				 void __pmem **kaddr, pfn_t *pfn, long size)
+{
+	struct mapped_device *md = bdev->bd_disk->private_data;
+	struct dm_table *map;
+	struct dm_target *ti;
+	int srcu_idx;
+	long len, ret = -EIO;
+
+	map = dm_get_live_table(md, &srcu_idx);
+	if (!map)
+		goto out;
+
+	ti = dm_table_find_target(map, sector);
+	if (!dm_target_is_valid(ti))
+		goto out;
+
+	len = max_io_len(sector, ti) << SECTOR_SHIFT;
+	size = min(len, size);
+
+	if (ti->type->direct_access)
+		ret = ti->type->direct_access(ti, sector, kaddr, pfn, size);
+out:
+	dm_put_live_table(md, srcu_idx);
+	return min(ret, size);
+}
 
 /*
  * A target may call dm_accept_partial_bio only from the map routine.  It is
···
 	return BLK_QC_T_NONE;
 }
 
-int dm_request_based(struct mapped_device *md)
-{
-	return blk_queue_stackable(md->queue);
-}
-
-static void dm_dispatch_clone_request(struct request *clone, struct request *rq)
-{
-	int r;
-
-	if (blk_queue_io_stat(clone->q))
-		clone->cmd_flags |= REQ_IO_STAT;
-
-	clone->start_time = jiffies;
-	r = blk_insert_cloned_request(clone->q, clone);
-	if (r)
-		/* must complete clone in terms of original request */
-		dm_complete_request(rq, r);
-}
-
-static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
-				 void *data)
-{
-	struct dm_rq_target_io *tio = data;
-	struct dm_rq_clone_bio_info *info =
-		container_of(bio, struct dm_rq_clone_bio_info, clone);
-
-	info->orig = bio_orig;
-	info->tio = tio;
-	bio->bi_end_io = end_clone_bio;
-
-	return 0;
-}
-
-static int setup_clone(struct request *clone, struct request *rq,
-		       struct dm_rq_target_io *tio, gfp_t gfp_mask)
-{
-	int r;
-
-	r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask,
-			      dm_rq_bio_constructor, tio);
-	if (r)
-		return r;
-
-	clone->cmd = rq->cmd;
-	clone->cmd_len = rq->cmd_len;
-	clone->sense = rq->sense;
-	clone->end_io = end_clone_request;
-	clone->end_io_data = tio;
-
-	tio->clone = clone;
-
-	return 0;
-}
-
-static struct request *clone_old_rq(struct request *rq, struct mapped_device *md,
-				    struct dm_rq_target_io *tio, gfp_t gfp_mask)
-{
-	/*
-	 * Create clone for use with .request_fn request_queue
-	 */
-	struct request *clone;
-
-	clone = alloc_old_clone_request(md, gfp_mask);
-	if (!clone)
-		return NULL;
-
-	blk_rq_init(NULL, clone);
-	if (setup_clone(clone, rq, tio, gfp_mask)) {
-		/* -ENOMEM */
-		free_old_clone_request(md, clone);
-		return NULL;
-	}
-
-	return clone;
-}
-
-static void map_tio_request(struct kthread_work *work);
-
-static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
-		     struct mapped_device *md)
-{
-	tio->md = md;
-	tio->ti = NULL;
-	tio->clone = NULL;
-	tio->orig = rq;
-	tio->error = 0;
-	/*
-	 * Avoid initializing info for blk-mq; it passes
-	 * target-specific data through info.ptr
-	 * (see: dm_mq_init_request)
-	 */
-	if (!md->init_tio_pdu)
-		memset(&tio->info, 0, sizeof(tio->info));
-	if (md->kworker_task)
-		init_kthread_work(&tio->work, map_tio_request);
-}
-
-static struct dm_rq_target_io *dm_old_prep_tio(struct request *rq,
-					       struct mapped_device *md,
-					       gfp_t gfp_mask)
-{
-	struct dm_rq_target_io *tio;
-	int srcu_idx;
-	struct dm_table *table;
-
-	tio = alloc_old_rq_tio(md, gfp_mask);
-	if (!tio)
-		return NULL;
-
-	init_tio(tio, rq, md);
-
-	table = dm_get_live_table(md, &srcu_idx);
-	/*
-	 * Must clone a request if this .request_fn DM device
-	 * is stacked on .request_fn device(s).
-	 */
-	if (!dm_table_mq_request_based(table)) {
-		if (!clone_old_rq(rq, md, tio, gfp_mask)) {
-			dm_put_live_table(md, srcu_idx);
-			free_old_rq_tio(tio);
-			return NULL;
-		}
-	}
-	dm_put_live_table(md, srcu_idx);
-
-	return tio;
-}
-
-/*
- * Called with the queue lock held.
- */
-static int dm_old_prep_fn(struct request_queue *q, struct request *rq)
-{
-	struct mapped_device *md = q->queuedata;
-	struct dm_rq_target_io *tio;
-
-	if (unlikely(rq->special)) {
-		DMWARN("Already has something in rq->special.");
-		return BLKPREP_KILL;
-	}
-
-	tio = dm_old_prep_tio(rq, md, GFP_ATOMIC);
-	if (!tio)
-		return BLKPREP_DEFER;
-
-	rq->special = tio;
-	rq->cmd_flags |= REQ_DONTPREP;
-
-	return BLKPREP_OK;
-}
-
-/*
- * Returns:
- * 0                : the request has been processed
- * DM_MAPIO_REQUEUE : the original request needs to be requeued
- * < 0              : the request was completed due to failure
- */
-static int map_request(struct dm_rq_target_io *tio, struct request *rq,
-		       struct mapped_device *md)
-{
-	int r;
-	struct dm_target *ti = tio->ti;
-	struct request *clone = NULL;
-
-	if (tio->clone) {
-		clone = tio->clone;
-		r = ti->type->map_rq(ti, clone, &tio->info);
-	} else {
-		r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
-		if (r < 0) {
-			/* The target wants to complete the I/O */
-			dm_kill_unmapped_request(rq, r);
-			return r;
-		}
-		if (r != DM_MAPIO_REMAPPED)
-			return r;
-		if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
-			/* -ENOMEM */
-			ti->type->release_clone_rq(clone);
-			return DM_MAPIO_REQUEUE;
-		}
-	}
-
-	switch (r) {
-	case DM_MAPIO_SUBMITTED:
-		/* The target has taken the I/O to submit by itself later */
-		break;
-	case DM_MAPIO_REMAPPED:
-		/* The target has remapped the I/O so dispatch it */
-		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
-				     blk_rq_pos(rq));
-		dm_dispatch_clone_request(clone, rq);
-		break;
-	case DM_MAPIO_REQUEUE:
-		/* The target wants to requeue the I/O */
-		dm_requeue_original_request(md, tio->orig);
-		break;
-	default:
-		if (r > 0) {
-			DMWARN("unimplemented target map return value: %d", r);
-			BUG();
-		}
-
-		/* The target wants to complete the I/O */
-		dm_kill_unmapped_request(rq, r);
-		return r;
-	}
-
-	return 0;
-}
-
-static void map_tio_request(struct kthread_work *work)
-{
-	struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work);
-	struct request *rq = tio->orig;
-	struct mapped_device *md = tio->md;
-
-	if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE)
-		dm_requeue_original_request(md, rq);
-}
-
-static void dm_start_request(struct mapped_device *md, struct request *orig)
-{
-	if (!orig->q->mq_ops)
-		blk_start_request(orig);
-	else
-		blk_mq_start_request(orig);
-	atomic_inc(&md->pending[rq_data_dir(orig)]);
-
-	if (md->seq_rq_merge_deadline_usecs) {
-		md->last_rq_pos = rq_end_sector(orig);
-		md->last_rq_rw = rq_data_dir(orig);
-		md->last_rq_start_time = ktime_get();
-	}
-
-	if (unlikely(dm_stats_used(&md->stats))) {
-		struct dm_rq_target_io *tio = tio_from_request(orig);
-		tio->duration_jiffies = jiffies;
-		tio->n_sectors = blk_rq_sectors(orig);
-		dm_stats_account_io(&md->stats, rq_data_dir(orig),
-				    blk_rq_pos(orig), tio->n_sectors, false, 0,
-				    &tio->stats_aux);
-	}
-
-	/*
-	 * Hold the md reference here for the in-flight I/O.
-	 * We can't rely on the reference count by device opener,
-	 * because the device may be closed during the request completion
-	 * when all bios are completed.
-	 * See the comment in rq_completed() too.
-	 */
-	dm_get(md);
-}
-
-#define MAX_SEQ_RQ_MERGE_DEADLINE_USECS 100000
-
-ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
-{
-	return sprintf(buf, "%u\n", md->seq_rq_merge_deadline_usecs);
-}
-
-ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
-						     const char *buf, size_t count)
-{
-	unsigned deadline;
-
-	if (!dm_request_based(md) || md->use_blk_mq)
-		return count;
-
-	if (kstrtouint(buf, 10, &deadline))
-		return -EINVAL;
-
-	if (deadline > MAX_SEQ_RQ_MERGE_DEADLINE_USECS)
-		deadline = MAX_SEQ_RQ_MERGE_DEADLINE_USECS;
-
-	md->seq_rq_merge_deadline_usecs = deadline;
-
-	return count;
-}
-
-static bool dm_request_peeked_before_merge_deadline(struct mapped_device *md)
-{
-	ktime_t kt_deadline;
-
-	if (!md->seq_rq_merge_deadline_usecs)
-		return false;
-
-	kt_deadline = ns_to_ktime((u64)md->seq_rq_merge_deadline_usecs * NSEC_PER_USEC);
-	kt_deadline = ktime_add_safe(md->last_rq_start_time, kt_deadline);
-
-	return !ktime_after(ktime_get(), kt_deadline);
-}
-
-/*
- * q->request_fn for request-based dm.
- * Called with the queue lock held.
- */
-static void dm_request_fn(struct request_queue *q)
-{
-	struct mapped_device *md = q->queuedata;
-	struct dm_target *ti = md->immutable_target;
-	struct request *rq;
-	struct dm_rq_target_io *tio;
-	sector_t pos = 0;
-
-	if (unlikely(!ti)) {
-		int srcu_idx;
-		struct dm_table *map = dm_get_live_table(md, &srcu_idx);
-
-		ti = dm_table_find_target(map, pos);
-		dm_put_live_table(md, srcu_idx);
-	}
-
-	/*
-	 * For suspend, check blk_queue_stopped() and increment
-	 * ->pending within a single queue_lock not to increment the
-	 * number of in-flight I/Os after the queue is stopped in
-	 * dm_suspend().
-	 */
-	while (!blk_queue_stopped(q)) {
-		rq = blk_peek_request(q);
-		if (!rq)
-			return;
-
-		/* always use block 0 to find the target for flushes for now */
-		pos = 0;
-		if (req_op(rq) != REQ_OP_FLUSH)
-			pos = blk_rq_pos(rq);
-
-		if ((dm_request_peeked_before_merge_deadline(md) &&
-		     md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&
-		     md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
-		    (ti->type->busy && ti->type->busy(ti))) {
-			blk_delay_queue(q, HZ / 100);
-			return;
-		}
-
-		dm_start_request(md, rq);
-
-		tio = tio_from_request(rq);
-		/* Establish tio->ti before queuing work (map_tio_request) */
-		tio->ti = ti;
-		queue_kthread_work(&md->kworker, &tio->work);
-		BUG_ON(!irqs_disabled());
-	}
-}
-
 static int dm_any_congested(void *congested_data, int bdi_bits)
 {
 	int r = bdi_bits;
···
 
 static void dm_wq_work(struct work_struct *work);
 
-static void dm_init_md_queue(struct mapped_device *md)
+void dm_init_md_queue(struct mapped_device *md)
 {
 	/*
 	 * Request-based dm devices cannot be stacked on top of bio-based dm
···
 	md->queue->backing_dev_info.congested_data = md;
 }
 
-static void dm_init_normal_md_queue(struct mapped_device *md)
+void dm_init_normal_md_queue(struct mapped_device *md)
 {
 	md->use_blk_mq = false;
 	dm_init_md_queue(md);
···
 		bdput(md->bdev);
 		md->bdev = NULL;
 	}
+
+	dm_mq_cleanup_mapped_device(md);
 }
 
 /*
···
 		goto bad_io_barrier;
 
 	md->numa_node_id = numa_node_id;
-	md->use_blk_mq = use_blk_mq;
+	md->use_blk_mq = dm_use_blk_mq_default();
 	md->init_tio_pdu = false;
 	md->type = DM_TYPE_NONE;
 	mutex_init(&md->suspend_lock);
···
 	unlock_fs(md);
 
 	cleanup_mapped_device(md);
-	if (md->tag_set) {
-		blk_mq_free_tag_set(md->tag_set);
-		kfree(md->tag_set);
-	}
 
 	free_table_devices(&md->table_devices);
 	dm_stats_cleanup(&md->stats);
···
 
 	if (md->bs) {
 		/* The md already has necessary mempools. */
-		if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {
+		if (dm_table_bio_based(t)) {
 			/*
 			 * Reload bioset because front_pad may have changed
 			 * because a different table was loaded.
···
 }
 EXPORT_SYMBOL_GPL(dm_get_queue_limits);
 
-static void dm_old_init_rq_based_worker_thread(struct mapped_device *md)
-{
-	/* Initialize the request-based DM worker thread */
-	init_kthread_worker(&md->kworker);
-	md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker,
-				       "kdmwork-%s", dm_device_name(md));
-}
-
-/*
- * Fully initialize a .request_fn request-based queue.
- */
-static int dm_old_init_request_queue(struct mapped_device *md)
-{
-	/* Fully initialize the queue */
-	if (!blk_init_allocated_queue(md->queue, dm_request_fn, NULL))
-		return -EINVAL;
-
-	/* disable dm_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);
-	blk_queue_prep_rq(md->queue, dm_old_prep_fn);
-
-	dm_old_init_rq_based_worker_thread(md);
-
-	elv_register_queue(md->queue);
-
-	return 0;
-}
-
-static int dm_mq_init_request(void *data, struct request *rq,
-			      unsigned int hctx_idx, unsigned int request_idx,
-			      unsigned int numa_node)
-{
-	struct mapped_device *md = data;
-	struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
-
-	/*
-	 * Must initialize md member of tio, otherwise it won't
-	 * be available in dm_mq_queue_rq.
-	 */
-	tio->md = md;
-
-	if (md->init_tio_pdu) {
-		/* target-specific per-io data is immediately after the tio */
-		tio->info.ptr = tio + 1;
-	}
-
-	return 0;
-}
-
-static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
-			  const struct blk_mq_queue_data *bd)
-{
-	struct request *rq = bd->rq;
-	struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
-	struct mapped_device *md = tio->md;
-	struct dm_target *ti = md->immutable_target;
-
-	if (unlikely(!ti)) {
-		int srcu_idx;
-		struct dm_table *map = dm_get_live_table(md, &srcu_idx);
-
-		ti = dm_table_find_target(map, 0);
-		dm_put_live_table(md, srcu_idx);
-	}
-
-	if (ti->type->busy && ti->type->busy(ti))
-		return BLK_MQ_RQ_QUEUE_BUSY;
-
-	dm_start_request(md, rq);
-
-	/* Init tio using md established in .init_request */
-	init_tio(tio, rq, md);
-
-	/*
-	 * Establish tio->ti before queuing work (map_tio_request)
-	 * or making direct call to map_request().
-	 */
-	tio->ti = ti;
-
-	/* Direct call is fine since .queue_rq allows allocations */
-	if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) {
-		/* Undo dm_start_request() before requeuing */
-		rq_end_stats(md, rq);
-		rq_completed(md, rq_data_dir(rq), false);
-		return BLK_MQ_RQ_QUEUE_BUSY;
-	}
-
-	return BLK_MQ_RQ_QUEUE_OK;
-}
-
-static struct blk_mq_ops dm_mq_ops = {
-	.queue_rq = dm_mq_queue_rq,
-	.map_queue = blk_mq_map_queue,
-	.complete = dm_softirq_done,
-	.init_request = dm_mq_init_request,
-};
-
-static int dm_mq_init_request_queue(struct mapped_device *md,
-				    struct dm_target *immutable_tgt)
-{
-	struct request_queue *q;
-	int err;
-
-	if (dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) {
-		DMERR("request-based dm-mq may only be stacked on blk-mq device(s)");
-		return -EINVAL;
-	}
-
-	md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
-	if (!md->tag_set)
-		return -ENOMEM;
-
-	md->tag_set->ops = &dm_mq_ops;
-	md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
-	md->tag_set->numa_node = md->numa_node_id;
-	md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
-	md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
-	md->tag_set->driver_data = md;
-
-	md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
-	if (immutable_tgt && immutable_tgt->per_io_data_size) {
-		/* any target-specific per-io data is immediately after the tio */
-		md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
-		md->init_tio_pdu = true;
-	}
-
-	err = blk_mq_alloc_tag_set(md->tag_set);
-	if (err)
-		goto out_kfree_tag_set;
-
-	q = blk_mq_init_allocated_queue(md->tag_set, md->queue);
-	if (IS_ERR(q)) {
-		err = PTR_ERR(q);
-		goto out_tag_set;
-	}
-	dm_init_md_queue(md);
-
-	/* backfill 'mq' sysfs registration normally done in blk_register_queue */
-	blk_mq_register_disk(md->disk);
-
-	return 0;
-
-out_tag_set:
-	blk_mq_free_tag_set(md->tag_set);
-out_kfree_tag_set:
-	kfree(md->tag_set);
-
-	return err;
-}
-
-static unsigned filter_md_type(unsigned type, struct mapped_device *md)
-{
-	if (type == DM_TYPE_BIO_BASED)
-		return type;
-
-	return !md->use_blk_mq ? DM_TYPE_REQUEST_BASED : DM_TYPE_MQ_REQUEST_BASED;
-}
-
 /*
  * Setup the DM device's queue based on md's type
  */
 int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
 {
 	int r;
-	unsigned md_type = filter_md_type(dm_get_md_type(md), md);
+	unsigned type = dm_get_md_type(md);
 
-	switch (md_type) {
+	switch (type) {
 	case DM_TYPE_REQUEST_BASED:
 		r = dm_old_init_request_queue(md);
 		if (r) {
···
 		}
 		break;
 	case DM_TYPE_MQ_REQUEST_BASED:
-		r = dm_mq_init_request_queue(md, dm_table_get_immutable_target(t));
+		r = dm_mq_init_request_queue(md, t);
 		if (r) {
 			DMERR("Cannot initialize queue for request-based dm-mq mapped device");
 			return r;
 		}
 		break;
 	case DM_TYPE_BIO_BASED:
+	case DM_TYPE_DAX_BIO_BASED:
 		dm_init_normal_md_queue(md);
 		blk_queue_make_request(md->queue, dm_make_request);
 		/*
···
 		 */
 		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;
 	}
 
···
 	if (!pools)
 		return NULL;
 
-	type = filter_md_type(type, md);
-
 	switch (type) {
 	case DM_TYPE_BIO_BASED:
+	case DM_TYPE_DAX_BIO_BASED:
 		cachep = _io_cache;
 		pool_size = dm_get_reserved_bio_based_ios();
 		front_pad = roundup(per_io_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
···
 	kfree(pools);
 }
 
+struct dm_pr {
+	u64	old_key;
+	u64	new_key;
+	u32	flags;
+	bool	fail_early;
+};
+
+static int dm_call_pr(struct block_device *bdev, iterate_devices_callout_fn fn,
+		      void *data)
+{
+	struct mapped_device *md = bdev->bd_disk->private_data;
+	struct dm_table *table;
+	struct dm_target *ti;
+	int ret = -ENOTTY, srcu_idx;
+
+	table = dm_get_live_table(md, &srcu_idx);
+	if (!table || !dm_table_get_size(table))
+		goto out;
+
+	/* We only support devices that have a single target */
+	if (dm_table_get_num_targets(table) != 1)
+		goto out;
+	ti = dm_table_get_target(table, 0);
+
+	ret = -EINVAL;
+	if (!ti->type->iterate_devices)
+		goto out;
+
+	ret = ti->type->iterate_devices(ti, fn, data);
+out:
+	dm_put_live_table(md, srcu_idx);
+	return ret;
+}
+
+/*
+ * For register / unregister we need to manually call out to every path.
+ */
+static int __dm_pr_register(struct dm_target *ti, struct dm_dev *dev,
+			    sector_t start, sector_t len, void *data)
+{
+	struct dm_pr *pr = data;
+	const struct pr_ops *ops = dev->bdev->bd_disk->fops->pr_ops;
+
+	if (!ops || !ops->pr_register)
+		return -EOPNOTSUPP;
+	return ops->pr_register(dev->bdev, pr->old_key, pr->new_key, pr->flags);
+}
+
 static int dm_pr_register(struct block_device *bdev, u64 old_key, u64 new_key,
 			  u32 flags)
 {
-	struct mapped_device *md = bdev->bd_disk->private_data;
-	const struct pr_ops *ops;
-	fmode_t mode;
-	int r;
+	struct dm_pr pr = {
+		.old_key	= old_key,
+		.new_key	= new_key,
+		.flags		= flags,
+		.fail_early	= true,
+	};
+	int ret;
 
-	r = dm_grab_bdev_for_ioctl(md, &bdev, &mode);
-	if (r < 0)
-		return r;
+	ret = dm_call_pr(bdev, __dm_pr_register, &pr);
+	if (ret && new_key) {
+		/* unregister all paths if we failed to register any path */
+		pr.old_key = new_key;
+		pr.new_key = 0;
+		pr.flags = 0;
+		pr.fail_early = false;
+		dm_call_pr(bdev, __dm_pr_register, &pr);
+	}
 
-	ops = bdev->bd_disk->fops->pr_ops;
-	if (ops && ops->pr_register)
-		r = ops->pr_register(bdev, old_key, new_key, flags);
-	else
-		r = -EOPNOTSUPP;
-
-	bdput(bdev);
-	return r;
+	return ret;
 }
 
 static int dm_pr_reserve(struct block_device *bdev, u64 key, enum pr_type type,
···
 	.open = dm_blk_open,
 	.release = dm_blk_close,
 	.ioctl = dm_blk_ioctl,
+	.direct_access = dm_blk_direct_access,
 	.getgeo = dm_blk_getgeo,
 	.pr_ops = &dm_pr_ops,
 	.owner = THIS_MODULE
···
 
 module_param(reserved_bio_based_ios, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools");
-
-module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
-
-module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
-
-module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
-
-module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");
 
 module_param(dm_numa_node, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(dm_numa_node, "NUMA node for DM device memory allocations");

drivers/md/dm.h

···
 #include <linux/fs.h>
 #include <linux/device-mapper.h>
 #include <linux/list.h>
+#include <linux/moduleparam.h>
 #include <linux/blkdev.h>
 #include <linux/backing-dev.h>
 #include <linux/hdreg.h>
···
  * Status feature flags
  */
 #define DM_STATUS_NOFLUSH_FLAG		(1 << 0)
-
-/*
- * Type of table and mapped_device's mempool
- */
-#define DM_TYPE_NONE			0
-#define DM_TYPE_BIO_BASED		1
-#define DM_TYPE_REQUEST_BASED		2
-#define DM_TYPE_MQ_REQUEST_BASED	3
 
 /*
  * List of devices that a metadevice uses and should open/close.
···
 struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
 struct dm_target *dm_table_get_immutable_target(struct dm_table *t);
 struct dm_target *dm_table_get_wildcard_target(struct dm_table *t);
+bool dm_table_bio_based(struct dm_table *t);
 bool dm_table_request_based(struct dm_table *t);
-bool dm_table_mq_request_based(struct dm_table *t);
+bool dm_table_all_blk_mq_devices(struct dm_table *t);
 void dm_table_free_md_mempools(struct dm_table *t);
 struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
 
···
 /*
  * sysfs interface
  */
-struct dm_kobject_holder {
-	struct kobject kobj;
-	struct completion completion;
-};
-
-static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
-{
-	return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;
-}
-
 int dm_sysfs_init(struct mapped_device *md);
 void dm_sysfs_exit(struct mapped_device *md);
 struct kobject *dm_kobject(struct mapped_device *md);
···
 void dm_internal_suspend(struct mapped_device *md);
 void dm_internal_resume(struct mapped_device *md);
 
-bool dm_use_blk_mq(struct mapped_device *md);
-
 int dm_io_init(void);
 void dm_io_exit(void);
 
···
 void dm_free_md_mempools(struct dm_md_mempools *pools);
 
 /*
- * Helpers that are used by DM core
+ * Various helpers
  */
 unsigned dm_get_reserved_bio_based_ios(void);
-unsigned dm_get_reserved_rq_based_ios(void);
-
-static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen)
-{
-	return !maxlen || strlen(result) + 1 >= maxlen;
-}
-
-ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf);
-ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
-						     const char *buf, size_t count);
 
 #endif

drivers/md/persistent-data/dm-btree.c

···
 
 	if (flags & INTERNAL_NODE) {
 		i = lower_bound(n, key);
-		if (i < 0 || i >= nr_entries) {
+		if (i < 0) {
+			/*
+			 * avoid early -ENODATA return when all entries are
+			 * higher than the search @key.
+			 */
+			i = 0;
+		}
+		if (i >= nr_entries) {
 			r = -ENODATA;
 			goto out;
 		}

drivers/scsi/sd.c

···
 		return -EOPNOTSUPP;
 	return sd_pr_command(bdev, (flags & PR_FL_IGNORE_KEY) ? 0x06 : 0x00,
 			old_key, new_key, 0,
-			(1 << 0) /* APTPL */ |
-			(1 << 2) /* ALL_TG_PT */);
+			(1 << 0) /* APTPL */);
 }
 
 static int sd_pr_reserve(struct block_device *bdev, u64 key, enum pr_type type,

include/linux/device-mapper.h

···
 struct mapped_device;
 struct bio_vec;
 
+/*
+ * Type of table, mapped_device's mempool and request_queue
+ */
+#define DM_TYPE_NONE			0
+#define DM_TYPE_BIO_BASED		1
+#define DM_TYPE_REQUEST_BASED		2
+#define DM_TYPE_MQ_REQUEST_BASED	3
+#define DM_TYPE_DAX_BIO_BASED		4
+
 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
 
 union map_info {
···
  */
 typedef int (*dm_busy_fn) (struct dm_target *ti);
 
+/*
+ * Returns:
+ *  < 0 : error
+ * >= 0 : the number of bytes accessible at the address
+ */
+typedef long (*dm_direct_access_fn) (struct dm_target *ti, sector_t sector,
+				     void __pmem **kaddr, pfn_t *pfn, long size);
+
 void dm_error(const char *message);
 
 struct dm_dev {
···
 	dm_busy_fn busy;
 	dm_iterate_devices_fn iterate_devices;
 	dm_io_hints_fn io_hints;
+	dm_direct_access_fn direct_access;
 
 	/* For internal device-mapper use. */
 	struct list_head list;
···
  * Target_ctr should call this if it needs to add any callbacks.
  */
 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
+
+/*
+ * Target can use this to set the table's type.
+ * Can only ever be called from a target's ctr.
+ * Useful for "hybrid" target (supports both bio-based
+ * and request-based).
+ */
+void dm_table_set_type(struct dm_table *t, unsigned type);
 
 /*
  * Finally call this to make the table ready for use.

include/uapi/linux/dm-ioctl.h

···
 #define DM_DEV_SET_GEOMETRY	_IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR	4
-#define DM_VERSION_MINOR	34
+#define DM_VERSION_MINOR	35
 #define DM_VERSION_PATCHLEVEL	0
-#define DM_VERSION_EXTRA	"-ioctl (2015-10-28)"
+#define DM_VERSION_EXTRA	"-ioctl (2016-06-23)"
 
 /* Status bits */
 #define DM_READONLY_FLAG	(1 << 0) /* In/Out */