Merge tag 'dm-4.6-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - Most attention this cycle went to optimizing blk-mq request-based DM
   (dm-mq) that is used exclussively by DM multipath:

     - A stable fix for dm-mq that eliminates excessive context
       switching offers the biggest performance improvement (for both
       IOPs and throughput).

     - But more work is needed, during the next cycle, to reduce
       spinlock contention in DM multipath on large NUMA systems.

 - A stable fix for a NULL pointer seen when DM stats is enabled on a DM
   multipath device that must requeue an IO due to path failure.

 - A stable fix for DM snapshot to disallow the COW and origin devices
   from being identical.  This amounts to graceful failure in the face
   of userspace error because these devices shouldn't ever be identical.

 - Stable fixes for DM cache and DM thin provisioning to address crashes
   seen if/when their respective metadata device experiences failures
   that cause the transition to 'fail_io' mode.

 - The DM cache 'mq' policy is now an alias for the 'smq' policy.  The
   'smq' policy proved to be consistently better than 'mq'.  As such
   'mq', with all its complex user-facing tunables, has been eliminated.

 - Improve DM thin provisioning to consistently return -ENOSPC once the
   thin-pool's data volume is out of space.

 - Improve DM core to properly handle error propagation if
   bio_integrity_clone() fails in clone_bio().

 - Other small cleanups and improvements to DM core.

* tag 'dm-4.6-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (41 commits)
  dm: fix rq_end_stats() NULL pointer in dm_requeue_original_request()
  dm thin: consistently return -ENOSPC if pool has run out of data space
  dm cache: bump the target version
  dm cache: make sure every metadata function checks fail_io
  dm: add missing newline between DM_DEBUG_BLOCK_STACK_TRACING and DM_BUFIO
  dm cache policy smq: clarify that mq registration failure was for 'mq'
  dm: return error if bio_integrity_clone() fails in clone_bio()
  dm thin metadata: don't issue prefetches if a transaction abort has failed
  dm snapshot: disallow the COW and origin devices from being identical
  dm cache: make the 'mq' policy an alias for 'smq'
  dm: drop unnecessary assignment of md->queue
  dm: reorder 'struct mapped_device' members to fix alignment and holes
  dm: remove dummy definition of 'struct dm_table'
  dm: add 'dm_numa_node' module parameter
  dm thin metadata: remove needless newline from subtree_dec() DMERR message
  dm mpath: cleanup reinstate_path() et al based on code review
  dm mpath: remove __pgpath_busy forward declaration, rename to pgpath_busy
  dm mpath: switch from 'unsigned' to 'bool' for flags where appropriate
  dm round robin: use percpu 'repeat_count' and 'current_path'
  dm path selector: remove 'repeat_count' return from .select_path hook
  ...

1 files changed, 121 insertions, 95 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index cfa29f574c2a..677ba223e2ae 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -23,6 +23,7 @@
 #include <linux/delay.h>
 #include <scsi/scsi_dh.h>
 #include <linux/atomic.h>
+#include <linux/blk-mq.h>
 
 #define DM_MSG_PREFIX "multipath"
 #define DM_PG_INIT_DELAY_MSECS 2000
@@ -33,11 +34,12 @@ struct pgpath {
 	struct list_head list;
 
 	struct priority_group *pg;	/* Owning PG */
-	unsigned is_active;		/* Path status */
 	unsigned fail_count;		/* Cumulative failure count */
 
 	struct dm_path path;
 	struct delayed_work activate_path;
+
+	bool is_active:1;		/* Path status */
 };
 
 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
@@ -53,10 +55,10 @@ struct priority_group {
 	struct path_selector ps;
 
 	unsigned pg_num;		/* Reference number */
-	unsigned bypassed;		/* Temporarily bypass this PG? */
-
 	unsigned nr_pgpaths;		/* Number of paths in PG */
 	struct list_head pgpaths;
+
+	bool bypassed:1;		/* Temporarily bypass this PG? */
 };
 
 /* Multipath context */
@@ -74,21 +76,20 @@ struct multipath {
 
 	wait_queue_head_t pg_init_wait;	/* Wait for pg_init completion */
 
-	unsigned pg_init_required;	/* pg_init needs calling? */
 	unsigned pg_init_in_progress;	/* Only one pg_init allowed at once */
-	unsigned pg_init_delay_retry;	/* Delay pg_init retry? */
 
 	unsigned nr_valid_paths;	/* Total number of usable paths */
 	struct pgpath *current_pgpath;
 	struct priority_group *current_pg;
 	struct priority_group *next_pg;	/* Switch to this PG if set */
-	unsigned repeat_count;		/* I/Os left before calling PS again */
 
-	unsigned queue_io:1;		/* Must we queue all I/O? */
-	unsigned queue_if_no_path:1;	/* Queue I/O if last path fails? */
-	unsigned saved_queue_if_no_path:1; /* Saved state during suspension */
-	unsigned retain_attached_hw_handler:1; /* If there's already a hw_handler present, don't change it. */
-	unsigned pg_init_disabled:1;	/* pg_init is not currently allowed */
+	bool queue_io:1;		/* Must we queue all I/O? */
+	bool queue_if_no_path:1;	/* Queue I/O if last path fails? */
+	bool saved_queue_if_no_path:1;	/* Saved state during suspension */
+	bool retain_attached_hw_handler:1; /* If there's already a hw_handler present, don't change it. */
+	bool pg_init_disabled:1;	/* pg_init is not currently allowed */
+	bool pg_init_required:1;	/* pg_init needs calling? */
+	bool pg_init_delay_retry:1;	/* Delay pg_init retry? */
 
 	unsigned pg_init_retries;	/* Number of times to retry pg_init */
 	unsigned pg_init_count;		/* Number of times pg_init called */
@@ -120,7 +121,6 @@ static struct kmem_cache *_mpio_cache;
 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
 static void trigger_event(struct work_struct *work);
 static void activate_path(struct work_struct *work);
-static int __pgpath_busy(struct pgpath *pgpath);
 
 
 /*-----------------------------------------------
@@ -132,7 +132,7 @@ static struct pgpath *alloc_pgpath(void)
 	struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
 
 	if (pgpath) {
-		pgpath->is_active = 1;
+		pgpath->is_active = true;
 		INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
 	}
 
@@ -181,25 +181,31 @@ static void free_priority_group(struct priority_group *pg,
 	kfree(pg);
 }
 
-static struct multipath *alloc_multipath(struct dm_target *ti)
+static struct multipath *alloc_multipath(struct dm_target *ti, bool use_blk_mq)
 {
 	struct multipath *m;
-	unsigned min_ios = dm_get_reserved_rq_based_ios();
 
 	m = kzalloc(sizeof(*m), GFP_KERNEL);
 	if (m) {
 		INIT_LIST_HEAD(&m->priority_groups);
 		spin_lock_init(&m->lock);
-		m->queue_io = 1;
+		m->queue_io = true;
 		m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
 		INIT_WORK(&m->trigger_event, trigger_event);
 		init_waitqueue_head(&m->pg_init_wait);
 		mutex_init(&m->work_mutex);
-		m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
-		if (!m->mpio_pool) {
-			kfree(m);
-			return NULL;
+
+		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->ti = ti;
 		ti->private = m;
 	}
@@ -222,26 +228,41 @@ static void free_multipath(struct multipath *m)
 	kfree(m);
 }
 
-static int set_mapinfo(struct multipath *m, union map_info *info)
+static struct dm_mpath_io *get_mpio(union map_info *info)
+{
+	return info->ptr;
+}
+
+static struct dm_mpath_io *set_mpio(struct multipath *m, union map_info *info)
 {
 	struct dm_mpath_io *mpio;
 
+	if (!m->mpio_pool) {
+		/* Use blk-mq pdu memory requested via per_io_data_size */
+		mpio = get_mpio(info);
+		memset(mpio, 0, sizeof(*mpio));
+		return mpio;
+	}
+
 	mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
 	if (!mpio)
-		return -ENOMEM;
+		return NULL;
 
 	memset(mpio, 0, sizeof(*mpio));
 	info->ptr = mpio;
 
-	return 0;
+	return mpio;
 }
 
-static void clear_mapinfo(struct multipath *m, union map_info *info)
+static void clear_request_fn_mpio(struct multipath *m, union map_info *info)
 {
-	struct dm_mpath_io *mpio = info->ptr;
+	/* Only needed for non blk-mq (.request_fn) multipath */
+	if (m->mpio_pool) {
+		struct dm_mpath_io *mpio = info->ptr;
 
-	info->ptr = NULL;
-	mempool_free(mpio, m->mpio_pool);
+		info->ptr = NULL;
+		mempool_free(mpio, m->mpio_pool);
+	}
 }
 
 /*-----------------------------------------------
@@ -257,7 +278,7 @@ static int __pg_init_all_paths(struct multipath *m)
 		return 0;
 
 	m->pg_init_count++;
-	m->pg_init_required = 0;
+	m->pg_init_required = false;
 
 	/* Check here to reset pg_init_required */
 	if (!m->current_pg)
@@ -283,11 +304,11 @@ static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
 
 	/* Must we initialise the PG first, and queue I/O till it's ready? */
 	if (m->hw_handler_name) {
-		m->pg_init_required = 1;
-		m->queue_io = 1;
+		m->pg_init_required = true;
+		m->queue_io = true;
 	} else {
-		m->pg_init_required = 0;
-		m->queue_io = 0;
+		m->pg_init_required = false;
+		m->queue_io = false;
 	}
 
 	m->pg_init_count = 0;
@@ -298,7 +319,7 @@ static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
 {
 	struct dm_path *path;
 
-	path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
+	path = pg->ps.type->select_path(&pg->ps, nr_bytes);
 	if (!path)
 		return -ENXIO;
 
@@ -313,10 +334,10 @@ static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
 static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
 {
 	struct priority_group *pg;
-	unsigned bypassed = 1;
+	bool bypassed = true;
 
 	if (!m->nr_valid_paths) {
-		m->queue_io = 0;
+		m->queue_io = false;
 		goto failed;
 	}
 
@@ -344,7 +365,7 @@ static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
 				continue;
 			if (!__choose_path_in_pg(m, pg, nr_bytes)) {
 				if (!bypassed)
-					m->pg_init_delay_retry = 1;
+					m->pg_init_delay_retry = true;
 				return;
 			}
 		}
@@ -380,7 +401,7 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
 			   union map_info *map_context,
 			   struct request *rq, struct request **__clone)
 {
-	struct multipath *m = (struct multipath *) ti->private;
+	struct multipath *m = ti->private;
 	int r = DM_MAPIO_REQUEUE;
 	size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
 	struct pgpath *pgpath;
@@ -390,8 +411,7 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
 	spin_lock_irq(&m->lock);
 
 	/* Do we need to select a new pgpath? */
-	if (!m->current_pgpath ||
-	    (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
+	if (!m->current_pgpath || !m->queue_io)
 		__choose_pgpath(m, nr_bytes);
 
 	pgpath = m->current_pgpath;
@@ -405,11 +425,11 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
 		goto out_unlock;
 	}
 
-	if (set_mapinfo(m, map_context) < 0)
+	mpio = set_mpio(m, map_context);
+	if (!mpio)
 		/* ENOMEM, requeue */
 		goto out_unlock;
 
-	mpio = map_context->ptr;
 	mpio->pgpath = pgpath;
 	mpio->nr_bytes = nr_bytes;
 
@@ -418,17 +438,24 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
 	spin_unlock_irq(&m->lock);
 
 	if (clone) {
-		/* Old request-based interface: allocated clone is passed in */
+		/*
+		 * Old request-based interface: allocated clone is passed in.
+		 * Used by: .request_fn stacked on .request_fn path(s).
+		 */
 		clone->q = bdev_get_queue(bdev);
 		clone->rq_disk = bdev->bd_disk;
 		clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
 	} else {
-		/* blk-mq request-based interface */
-		*__clone = blk_get_request(bdev_get_queue(bdev),
-					   rq_data_dir(rq), GFP_ATOMIC);
+		/*
+		 * blk-mq request-based interface; used by both:
+		 * .request_fn stacked on blk-mq path(s) and
+		 * blk-mq stacked on blk-mq path(s).
+		 */
+		*__clone = blk_mq_alloc_request(bdev_get_queue(bdev),
+						rq_data_dir(rq), BLK_MQ_REQ_NOWAIT);
 		if (IS_ERR(*__clone)) {
 			/* ENOMEM, requeue */
-			clear_mapinfo(m, map_context);
+			clear_request_fn_mpio(m, map_context);
 			return r;
 		}
 		(*__clone)->bio = (*__clone)->biotail = NULL;
@@ -463,14 +490,14 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
 
 static void multipath_release_clone(struct request *clone)
 {
-	blk_put_request(clone);
+	blk_mq_free_request(clone);
 }
 
 /*
  * If we run out of usable paths, should we queue I/O or error it?
  */
-static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
-			    unsigned save_old_value)
+static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
+			    bool save_old_value)
 {
 	unsigned long flags;
 
@@ -776,12 +803,12 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m)
 		argc--;
 
 		if (!strcasecmp(arg_name, "queue_if_no_path")) {
-			r = queue_if_no_path(m, 1, 0);
+			r = queue_if_no_path(m, true, false);
 			continue;
 		}
 
 		if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
-			m->retain_attached_hw_handler = 1;
+			m->retain_attached_hw_handler = true;
 			continue;
 		}
 
@@ -820,11 +847,12 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 	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);
+	m = alloc_multipath(ti, use_blk_mq);
 	if (!m) {
 		ti->error = "can't allocate multipath";
 		return -EINVAL;
@@ -880,6 +908,8 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->num_write_same_bios = 1;
+	if (use_blk_mq)
+		ti->per_io_data_size = sizeof(struct dm_mpath_io);
 
 	return 0;
 
@@ -917,7 +947,7 @@ static void flush_multipath_work(struct multipath *m)
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-	m->pg_init_disabled = 1;
+	m->pg_init_disabled = true;
 	spin_unlock_irqrestore(&m->lock, flags);
 
 	flush_workqueue(kmpath_handlerd);
@@ -926,7 +956,7 @@ static void flush_multipath_work(struct multipath *m)
 	flush_work(&m->trigger_event);
 
 	spin_lock_irqsave(&m->lock, flags);
-	m->pg_init_disabled = 0;
+	m->pg_init_disabled = false;
 	spin_unlock_irqrestore(&m->lock, flags);
 }
 
@@ -954,7 +984,7 @@ static int fail_path(struct pgpath *pgpath)
 	DMWARN("Failing path %s.", pgpath->path.dev->name);
 
 	pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
-	pgpath->is_active = 0;
+	pgpath->is_active = false;
 	pgpath->fail_count++;
 
 	m->nr_valid_paths--;
@@ -987,18 +1017,13 @@ static int reinstate_path(struct pgpath *pgpath)
 	if (pgpath->is_active)
 		goto out;
 
-	if (!pgpath->pg->ps.type->reinstate_path) {
-		DMWARN("Reinstate path not supported by path selector %s",
-		       pgpath->pg->ps.type->name);
-		r = -EINVAL;
-		goto out;
-	}
+	DMWARN("Reinstating path %s.", pgpath->path.dev->name);
 
 	r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
 	if (r)
 		goto out;
 
-	pgpath->is_active = 1;
+	pgpath->is_active = true;
 
 	if (!m->nr_valid_paths++) {
 		m->current_pgpath = NULL;
@@ -1045,7 +1070,7 @@ static int action_dev(struct multipath *m, struct dm_dev *dev,
  * Temporarily try to avoid having to use the specified PG
  */
 static void bypass_pg(struct multipath *m, struct priority_group *pg,
-		      int bypassed)
+		      bool bypassed)
 {
 	unsigned long flags;
 
@@ -1078,7 +1103,7 @@ static int switch_pg_num(struct multipath *m, const char *pgstr)
 
 	spin_lock_irqsave(&m->lock, flags);
 	list_for_each_entry(pg, &m->priority_groups, list) {
-		pg->bypassed = 0;
+		pg->bypassed = false;
 		if (--pgnum)
 			continue;
 
@@ -1096,7 +1121,7 @@ static int switch_pg_num(struct multipath *m, const char *pgstr)
  * Set/clear bypassed status of a PG.
  * PGs are numbered upwards from 1 in the order they were declared.
  */
-static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
+static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
 {
 	struct priority_group *pg;
 	unsigned pgnum;
@@ -1120,17 +1145,17 @@ static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
 /*
  * Should we retry pg_init immediately?
  */
-static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
+static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
 {
 	unsigned long flags;
-	int limit_reached = 0;
+	bool limit_reached = false;
 
 	spin_lock_irqsave(&m->lock, flags);
 
 	if (m->pg_init_count <= m->pg_init_retries && !m->pg_init_disabled)
-		m->pg_init_required = 1;
+		m->pg_init_required = true;
 	else
-		limit_reached = 1;
+		limit_reached = true;
 
 	spin_unlock_irqrestore(&m->lock, flags);
 
@@ -1143,7 +1168,7 @@ static void pg_init_done(void *data, int errors)
 	struct priority_group *pg = pgpath->pg;
 	struct multipath *m = pg->m;
 	unsigned long flags;
-	unsigned delay_retry = 0;
+	bool delay_retry = false;
 
 	/* device or driver problems */
 	switch (errors) {
@@ -1166,7 +1191,7 @@ static void pg_init_done(void *data, int errors)
 		 * Probably doing something like FW upgrade on the
 		 * controller so try the other pg.
 		 */
-		bypass_pg(m, pg, 1);
+		bypass_pg(m, pg, true);
 		break;
 	case SCSI_DH_RETRY:
 		/* Wait before retrying. */
@@ -1177,6 +1202,7 @@ static void pg_init_done(void *data, int errors)
 			fail_path(pgpath);
 		errors = 0;
 		break;
+	case SCSI_DH_DEV_OFFLINED:
 	default:
 		/*
 		 * We probably do not want to fail the path for a device
@@ -1194,7 +1220,7 @@ static void pg_init_done(void *data, int errors)
 			m->current_pg = NULL;
 		}
 	} else if (!m->pg_init_required)
-		pg->bypassed = 0;
+		pg->bypassed = false;
 
 	if (--m->pg_init_in_progress)
 		/* Activations of other paths are still on going */
@@ -1205,7 +1231,7 @@ static void pg_init_done(void *data, int errors)
 		if (__pg_init_all_paths(m))
 			goto out;
 	}
-	m->queue_io = 0;
+	m->queue_io = false;
 
 	/*
 	 * Wake up any thread waiting to suspend.
@@ -1291,21 +1317,21 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
 			    int error, union map_info *map_context)
 {
 	struct multipath *m = ti->private;
-	struct dm_mpath_io *mpio = map_context->ptr;
+	struct dm_mpath_io *mpio = get_mpio(map_context);
 	struct pgpath *pgpath;
 	struct path_selector *ps;
 	int r;
 
 	BUG_ON(!mpio);
 
-	r  = do_end_io(m, clone, error, mpio);
+	r = do_end_io(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);
 	}
-	clear_mapinfo(m, map_context);
+	clear_request_fn_mpio(m, map_context);
 
 	return r;
 }
@@ -1318,9 +1344,9 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
  */
 static void multipath_presuspend(struct dm_target *ti)
 {
-	struct multipath *m = (struct multipath *) ti->private;
+	struct multipath *m = ti->private;
 
-	queue_if_no_path(m, 0, 1);
+	queue_if_no_path(m, false, true);
 }
 
 static void multipath_postsuspend(struct dm_target *ti)
@@ -1337,7 +1363,7 @@ static void multipath_postsuspend(struct dm_target *ti)
  */
 static void multipath_resume(struct dm_target *ti)
 {
-	struct multipath *m = (struct multipath *) ti->private;
+	struct multipath *m = ti->private;
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
@@ -1366,7 +1392,7 @@ static void multipath_status(struct dm_target *ti, status_type_t type,
 {
 	int sz = 0;
 	unsigned long flags;
-	struct multipath *m = (struct multipath *) ti->private;
+	struct multipath *m = ti->private;
 	struct priority_group *pg;
 	struct pgpath *p;
 	unsigned pg_num;
@@ -1474,7 +1500,7 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 {
 	int r = -EINVAL;
 	struct dm_dev *dev;
-	struct multipath *m = (struct multipath *) ti->private;
+	struct multipath *m = ti->private;
 	action_fn action;
 
 	mutex_lock(&m->work_mutex);
@@ -1486,10 +1512,10 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 
 	if (argc == 1) {
 		if (!strcasecmp(argv[0], "queue_if_no_path")) {
-			r = queue_if_no_path(m, 1, 0);
+			r = queue_if_no_path(m, true, false);
 			goto out;
 		} else if (!strcasecmp(argv[0], "fail_if_no_path")) {
-			r = queue_if_no_path(m, 0, 0);
+			r = queue_if_no_path(m, false, false);
 			goto out;
 		}
 	}
@@ -1500,10 +1526,10 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 	}
 
 	if (!strcasecmp(argv[0], "disable_group")) {
-		r = bypass_pg_num(m, argv[1], 1);
+		r = bypass_pg_num(m, argv[1], true);
 		goto out;
 	} else if (!strcasecmp(argv[0], "enable_group")) {
-		r = bypass_pg_num(m, argv[1], 0);
+		r = bypass_pg_num(m, argv[1], false);
 		goto out;
 	} else if (!strcasecmp(argv[0], "switch_group")) {
 		r = switch_pg_num(m, argv[1]);
@@ -1604,7 +1630,7 @@ out:
 	return ret;
 }
 
-static int __pgpath_busy(struct pgpath *pgpath)
+static int pgpath_busy(struct pgpath *pgpath)
 {
 	struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
 
@@ -1621,7 +1647,7 @@ static int __pgpath_busy(struct pgpath *pgpath)
  */
 static int multipath_busy(struct dm_target *ti)
 {
-	int busy = 0, has_active = 0;
+	bool busy = false, has_active = false;
 	struct multipath *m = ti->private;
 	struct priority_group *pg;
 	struct pgpath *pgpath;
@@ -1632,7 +1658,7 @@ static int multipath_busy(struct dm_target *ti)
 	/* pg_init in progress or no paths available */
 	if (m->pg_init_in_progress ||
 	    (!m->nr_valid_paths && m->queue_if_no_path)) {
-		busy = 1;
+		busy = true;
 		goto out;
 	}
 	/* Guess which priority_group will be used at next mapping time */
@@ -1654,13 +1680,12 @@ static int multipath_busy(struct dm_target *ti)
 	 * If there is one non-busy active path at least, the path selector
 	 * will be able to select it. So we consider such a pg as not busy.
 	 */
-	busy = 1;
+	busy = true;
 	list_for_each_entry(pgpath, &pg->pgpaths, list)
 		if (pgpath->is_active) {
-			has_active = 1;
-
-			if (!__pgpath_busy(pgpath)) {
-				busy = 0;
+			has_active = true;
+			if (!pgpath_busy(pgpath)) {
+				busy = false;
 				break;
 			}
 		}
@@ -1671,7 +1696,7 @@ static int multipath_busy(struct dm_target *ti)
 		 * the current_pg will be changed at next mapping time.
 		 * We need to try mapping to determine it.
 		 */
-		busy = 0;
+		busy = false;
 
 out:
 	spin_unlock_irqrestore(&m->lock, flags);
@@ -1684,7 +1709,8 @@ out:
  *---------------------------------------------------------------*/
 static struct target_type multipath_target = {
 	.name = "multipath",
-	.version = {1, 10, 0},
+	.version = {1, 11, 0},
+	.features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
 	.module = THIS_MODULE,
 	.ctr = multipath_ctr,
 	.dtr = multipath_dtr,