1 files changed, 146 insertions, 270 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 3570bcb7a4a4..0e8ab5bb3575 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -90,13 +90,7 @@ struct multipath {
 	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.
-	 */
-	mempool_t *mpio_pool;
+	enum dm_queue_mode queue_mode;
 
 	struct mutex work_mutex;
 	struct work_struct trigger_event;
@@ -115,11 +109,10 @@ struct dm_mpath_io {
 
 typedef int (*action_fn) (struct pgpath *pgpath);
 
-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 void activate_or_offline_path(struct pgpath *pgpath);
+static void activate_path_work(struct work_struct *work);
 static void process_queued_bios(struct work_struct *work);
 
 /*-----------------------------------------------
@@ -144,7 +137,7 @@ static struct pgpath *alloc_pgpath(void)
 
 	if (pgpath) {
 		pgpath->is_active = true;
-		INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
+		INIT_DELAYED_WORK(&pgpath->activate_path, activate_path_work);
 	}
 
 	return pgpath;
@@ -209,7 +202,6 @@ static struct multipath *alloc_multipath(struct dm_target *ti)
 		init_waitqueue_head(&m->pg_init_wait);
 		mutex_init(&m->work_mutex);
 
-		m->mpio_pool = NULL;
 		m->queue_mode = DM_TYPE_NONE;
 
 		m->ti = ti;
@@ -229,16 +221,7 @@ static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
 			m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
 		else
 			m->queue_mode = DM_TYPE_REQUEST_BASED;
-	}
-
-	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) {
+	} 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;
@@ -263,7 +246,6 @@ static void free_multipath(struct multipath *m)
 
 	kfree(m->hw_handler_name);
 	kfree(m->hw_handler_params);
-	mempool_destroy(m->mpio_pool);
 	kfree(m);
 }
 
@@ -272,38 +254,6 @@ 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 NULL;
-
-	memset(mpio, 0, sizeof(*mpio));
-	info->ptr = mpio;
-
-	return mpio;
-}
-
-static void clear_request_fn_mpio(struct multipath *m, union map_info *info)
-{
-	/* 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);
-	}
-}
-
 static size_t multipath_per_bio_data_size(void)
 {
 	return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
@@ -348,6 +298,8 @@ static int __pg_init_all_paths(struct multipath *m)
 	struct pgpath *pgpath;
 	unsigned long pg_init_delay = 0;
 
+	lockdep_assert_held(&m->lock);
+
 	if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
 		return 0;
 
@@ -372,13 +324,16 @@ static int __pg_init_all_paths(struct multipath *m)
 	return atomic_read(&m->pg_init_in_progress);
 }
 
-static void pg_init_all_paths(struct multipath *m)
+static int pg_init_all_paths(struct multipath *m)
 {
+	int ret;
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-	__pg_init_all_paths(m);
+	ret = __pg_init_all_paths(m);
 	spin_unlock_irqrestore(&m->lock, flags);
+
+	return ret;
 }
 
 static void __switch_pg(struct multipath *m, struct priority_group *pg)
@@ -487,59 +442,35 @@ failed:
 }
 
 /*
- * Check whether bios must be queued in the device-mapper core rather
- * than here in the target.
- *
- * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
- * same value then we are not between multipath_presuspend()
- * and multipath_resume() calls and we have no need to check
- * for the DMF_NOFLUSH_SUSPENDING flag.
+ * dm_report_EIO() is a macro instead of a function to make pr_debug()
+ * report the function name and line number of the function from which
+ * it has been invoked.
  */
-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)
-{
-	bool r;
-	unsigned long flags;
-
-	spin_lock_irqsave(&m->lock, flags);
-	r = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
-	     __must_push_back(m));
-	spin_unlock_irqrestore(&m->lock, flags);
-
-	return r;
-}
-
-static bool must_push_back_bio(struct multipath *m)
-{
-	bool r;
-	unsigned long flags;
-
-	spin_lock_irqsave(&m->lock, flags);
-	r = __must_push_back(m);
-	spin_unlock_irqrestore(&m->lock, flags);
-
-	return r;
-}
+#define dm_report_EIO(m)						\
+do {									\
+	struct mapped_device *md = dm_table_get_md((m)->ti->table);	\
+									\
+	pr_debug("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d\n", \
+		 dm_device_name(md),					\
+		 test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags),	\
+		 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags),	\
+		 dm_noflush_suspending((m)->ti));			\
+} while (0)
 
 /*
  * Map cloned requests (request-based multipath)
  */
-static int __multipath_map(struct dm_target *ti, struct request *clone,
-			   union map_info *map_context,
-			   struct request *rq, struct request **__clone)
+static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
+				   union map_info *map_context,
+				   struct request **__clone)
 {
 	struct multipath *m = ti->private;
-	int r = DM_MAPIO_REQUEUE;
-	size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
+	size_t nr_bytes = blk_rq_bytes(rq);
 	struct pgpath *pgpath;
 	struct block_device *bdev;
-	struct dm_mpath_io *mpio;
+	struct dm_mpath_io *mpio = get_mpio(map_context);
+	struct request_queue *q;
+	struct request *clone;
 
 	/* Do we need to select a new pgpath? */
 	pgpath = lockless_dereference(m->current_pgpath);
@@ -547,51 +478,40 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
 		pgpath = choose_pgpath(m, nr_bytes);
 
 	if (!pgpath) {
-		if (must_push_back_rq(m))
+		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
 			return DM_MAPIO_DELAY_REQUEUE;
-		return -EIO;	/* Failed */
+		dm_report_EIO(m);	/* Failed */
+		return DM_MAPIO_KILL;
 	} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
 		   test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
-		pg_init_all_paths(m);
-		return r;
+		if (pg_init_all_paths(m))
+			return DM_MAPIO_DELAY_REQUEUE;
+		return DM_MAPIO_REQUEUE;
 	}
 
-	mpio = set_mpio(m, map_context);
-	if (!mpio)
-		/* ENOMEM, requeue */
-		return r;
-
+	memset(mpio, 0, sizeof(*mpio));
 	mpio->pgpath = pgpath;
 	mpio->nr_bytes = nr_bytes;
 
 	bdev = pgpath->path.dev->bdev;
-
-	if (clone) {
-		/*
-		 * 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; 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)) {
-			/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
-			clear_request_fn_mpio(m, map_context);
-			return r;
+	q = bdev_get_queue(bdev);
+	clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE, GFP_ATOMIC);
+	if (IS_ERR(clone)) {
+		/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
+		bool queue_dying = blk_queue_dying(q);
+		DMERR_LIMIT("blk_get_request() returned %ld%s - requeuing",
+			    PTR_ERR(clone), queue_dying ? " (path offline)" : "");
+		if (queue_dying) {
+			atomic_inc(&m->pg_init_in_progress);
+			activate_or_offline_path(pgpath);
+			return DM_MAPIO_REQUEUE;
 		}
-		clone->bio = clone->biotail = NULL;
-		clone->rq_disk = bdev->bd_disk;
-		clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
-		*__clone = clone;
+		return DM_MAPIO_DELAY_REQUEUE;
 	}
+	clone->bio = clone->biotail = NULL;
+	clone->rq_disk = bdev->bd_disk;
+	clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+	*__clone = clone;
 
 	if (pgpath->pg->ps.type->start_io)
 		pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
@@ -600,22 +520,9 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
 	return DM_MAPIO_REMAPPED;
 }
 
-static int multipath_map(struct dm_target *ti, struct request *clone,
-			 union map_info *map_context)
-{
-	return __multipath_map(ti, clone, map_context, NULL, NULL);
-}
-
-static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
-				   union map_info *map_context,
-				   struct request **clone)
-{
-	return __multipath_map(ti, NULL, map_context, rq, clone);
-}
-
 static void multipath_release_clone(struct request *clone)
 {
-	blk_mq_free_request(clone);
+	blk_put_request(clone);
 }
 
 /*
@@ -649,15 +556,16 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
 	}
 
 	if (!pgpath) {
-		if (!must_push_back_bio(m))
-			return -EIO;
-		return DM_MAPIO_REQUEUE;
+		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
+			return DM_MAPIO_REQUEUE;
+		dm_report_EIO(m);
+		return DM_MAPIO_KILL;
 	}
 
 	mpio->pgpath = pgpath;
 	mpio->nr_bytes = nr_bytes;
 
-	bio->bi_error = 0;
+	bio->bi_status = 0;
 	bio->bi_bdev = pgpath->path.dev->bdev;
 	bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
 
@@ -713,15 +621,31 @@ static void process_queued_bios(struct work_struct *work)
 	blk_start_plug(&plug);
 	while ((bio = bio_list_pop(&bios))) {
 		r = __multipath_map_bio(m, bio, get_mpio_from_bio(bio));
-		if (r < 0 || r == DM_MAPIO_REQUEUE) {
-			bio->bi_error = r;
+		switch (r) {
+		case DM_MAPIO_KILL:
+			bio->bi_status = BLK_STS_IOERR;
+			bio_endio(bio);
+			break;
+		case DM_MAPIO_REQUEUE:
+			bio->bi_status = BLK_STS_DM_REQUEUE;
 			bio_endio(bio);
-		} else if (r == DM_MAPIO_REMAPPED)
+			break;
+		case DM_MAPIO_REMAPPED:
 			generic_make_request(bio);
+			break;
+		}
 	}
 	blk_finish_plug(&plug);
 }
 
+static void assign_bit(bool value, long nr, unsigned long *addr)
+{
+	if (value)
+		set_bit(nr, addr);
+	else
+		clear_bit(nr, addr);
+}
+
 /*
  * If we run out of usable paths, should we queue I/O or error it?
  */
@@ -731,23 +655,11 @@ static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-
-	if (save_old_value) {
-		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
-			set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
-		else
-			clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
-	} else {
-		if (queue_if_no_path)
-			set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
-		else
-			clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
-	}
-	if (queue_if_no_path)
-		set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
-	else
-		clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
-
+	assign_bit((save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
+		   (!save_old_value && queue_if_no_path),
+		   MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
+	assign_bit(queue_if_no_path || dm_noflush_suspending(m->ti),
+		   MPATHF_QUEUE_IF_NO_PATH, &m->flags);
 	spin_unlock_irqrestore(&m->lock, flags);
 
 	if (!queue_if_no_path) {
@@ -1185,9 +1097,10 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->num_write_same_bios = 1;
+	ti->num_write_zeroes_bios = 1;
 	if (m->queue_mode == DM_TYPE_BIO_BASED)
 		ti->per_io_data_size = multipath_per_bio_data_size();
-	else if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
+	else
 		ti->per_io_data_size = sizeof(struct dm_mpath_io);
 
 	return 0;
@@ -1519,10 +1432,8 @@ out:
 	spin_unlock_irqrestore(&m->lock, flags);
 }
 
-static void activate_path(struct work_struct *work)
+static void activate_or_offline_path(struct pgpath *pgpath)
 {
-	struct pgpath *pgpath =
-		container_of(work, struct pgpath, activate_path.work);
 	struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
 
 	if (pgpath->is_active && !blk_queue_dying(q))
@@ -1531,22 +1442,23 @@ static void activate_path(struct work_struct *work)
 		pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
 }
 
-static int noretry_error(int error)
+static void activate_path_work(struct work_struct *work)
+{
+	struct pgpath *pgpath =
+		container_of(work, struct pgpath, activate_path.work);
+
+	activate_or_offline_path(pgpath);
+}
+
+static int noretry_error(blk_status_t error)
 {
 	switch (error) {
-	case -EBADE:
-		/*
-		 * EBADE signals an reservation conflict.
-		 * We shouldn't fail the path here as we can communicate with
-		 * the target.  We should failover to the next path, but in
-		 * doing so we might be causing a ping-pong between paths.
-		 * So just return the reservation conflict error.
-		 */
-	case -EOPNOTSUPP:
-	case -EREMOTEIO:
-	case -EILSEQ:
-	case -ENODATA:
-	case -ENOSPC:
+	case BLK_STS_NOTSUPP:
+	case BLK_STS_NOSPC:
+	case BLK_STS_TARGET:
+	case BLK_STS_NEXUS:
+	case BLK_STS_MEDIUM:
+	case BLK_STS_RESOURCE:
 		return 1;
 	}
 
@@ -1554,12 +1466,13 @@ static int noretry_error(int error)
 	return 0;
 }
 
-/*
- * end_io handling
- */
-static int do_end_io(struct multipath *m, struct request *clone,
-		     int error, struct dm_mpath_io *mpio)
+static int multipath_end_io(struct dm_target *ti, struct request *clone,
+			    blk_status_t error, union map_info *map_context)
 {
+	struct dm_mpath_io *mpio = get_mpio(map_context);
+	struct pgpath *pgpath = mpio->pgpath;
+	int r = DM_ENDIO_DONE;
+
 	/*
 	 * We don't queue any clone request inside the multipath target
 	 * during end I/O handling, since those clone requests don't have
@@ -1571,70 +1484,53 @@ static int do_end_io(struct multipath *m, struct request *clone,
 	 * request into dm core, which will remake a clone request and
 	 * clone bios for it and resubmit it later.
 	 */
-	int r = DM_ENDIO_REQUEUE;
+	if (error && !noretry_error(error)) {
+		struct multipath *m = ti->private;
 
-	if (!error && !clone->errors)
-		return 0;	/* I/O complete */
+		r = DM_ENDIO_REQUEUE;
 
-	if (noretry_error(error))
-		return error;
-
-	if (mpio->pgpath)
-		fail_path(mpio->pgpath);
+		if (pgpath)
+			fail_path(pgpath);
 
-	if (!atomic_read(&m->nr_valid_paths)) {
-		if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
-			if (!must_push_back_rq(m))
-				r = -EIO;
+		if (atomic_read(&m->nr_valid_paths) == 0 &&
+		    !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
+			if (error == BLK_STS_IOERR)
+				dm_report_EIO(m);
+			/* complete with the original error */
+			r = DM_ENDIO_DONE;
 		}
 	}
 
-	return r;
-}
-
-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 = get_mpio(map_context);
-	struct pgpath *pgpath;
-	struct path_selector *ps;
-	int r;
-
-	BUG_ON(!mpio);
-
-	r = do_end_io(m, clone, error, mpio);
-	pgpath = mpio->pgpath;
 	if (pgpath) {
-		ps = &pgpath->pg->ps;
+		struct path_selector *ps = &pgpath->pg->ps;
+
 		if (ps->type->end_io)
 			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)
+static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
+		blk_status_t *error)
 {
+	struct multipath *m = ti->private;
+	struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
+	struct pgpath *pgpath = mpio->pgpath;
 	unsigned long flags;
+	int r = DM_ENDIO_DONE;
 
-	if (!error)
-		return 0;	/* I/O complete */
-
-	if (noretry_error(error))
-		return error;
+	if (!*error || noretry_error(*error))
+		goto done;
 
-	if (mpio->pgpath)
-		fail_path(mpio->pgpath);
+	if (pgpath)
+		fail_path(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;
-		}
+	if (atomic_read(&m->nr_valid_paths) == 0 &&
+	    !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
+		dm_report_EIO(m);
+		*error = BLK_STS_IOERR;
+		goto done;
 	}
 
 	/* Queue for the daemon to resubmit */
@@ -1646,23 +1542,11 @@ static int do_end_io_bio(struct multipath *m, struct bio *clone,
 	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;
+	r = DM_ENDIO_INCOMPLETE;
+done:
 	if (pgpath) {
-		ps = &pgpath->pg->ps;
+		struct path_selector *ps = &pgpath->pg->ps;
+
 		if (ps->type->end_io)
 			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
 	}
@@ -1701,10 +1585,8 @@ static void multipath_resume(struct dm_target *ti)
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-	if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags))
-		set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
-	else
-		clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
+	assign_bit(test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
+		   MPATHF_QUEUE_IF_NO_PATH, &m->flags);
 	spin_unlock_irqrestore(&m->lock, flags);
 }
 
@@ -1764,6 +1646,9 @@ static void multipath_status(struct dm_target *ti, status_type_t type,
 			case DM_TYPE_MQ_REQUEST_BASED:
 				DMEMIT("queue_mode mq ");
 				break;
+			default:
+				WARN_ON_ONCE(true);
+				break;
 			}
 		}
 	}
@@ -2060,7 +1945,6 @@ static struct target_type multipath_target = {
 	.module = THIS_MODULE,
 	.ctr = multipath_ctr,
 	.dtr = multipath_dtr,
-	.map_rq = multipath_map,
 	.clone_and_map_rq = multipath_clone_and_map,
 	.release_clone_rq = multipath_release_clone,
 	.rq_end_io = multipath_end_io,
@@ -2080,11 +1964,6 @@ static int __init dm_multipath_init(void)
 {
 	int r;
 
-	/* 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("request-based register failed %d", r);
@@ -2120,8 +1999,6 @@ bad_alloc_kmpath_handlerd:
 bad_alloc_kmultipathd:
 	dm_unregister_target(&multipath_target);
 bad_register_target:
-	kmem_cache_destroy(_mpio_cache);
-
 	return r;
 }
 
@@ -2131,7 +2008,6 @@ static void __exit dm_multipath_exit(void)
 	destroy_workqueue(kmultipathd);
 
 	dm_unregister_target(&multipath_target);
-	kmem_cache_destroy(_mpio_cache);
 }
 
 module_init(dm_multipath_init);