1 files changed, 367 insertions, 276 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 724efc63904d..3167480b532c 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -143,9 +143,19 @@ struct mapped_device {
 	int barrier_error;
 
 	/*
+	 * Protect barrier_error from concurrent endio processing
+	 * in request-based dm.
+	 */
+	spinlock_t barrier_error_lock;
+
+	/*
 	 * Processing queue (flush/barriers)
 	 */
 	struct workqueue_struct *wq;
+	struct work_struct barrier_work;
+
+	/* A pointer to the currently processing pre/post flush request */
+	struct request *flush_request;
 
 	/*
 	 * The current mapping.
@@ -178,9 +188,6 @@ struct mapped_device {
 	/* forced geometry settings */
 	struct hd_geometry geometry;
 
-	/* marker of flush suspend for request-based dm */
-	struct request suspend_rq;
-
 	/* For saving the address of __make_request for request based dm */
 	make_request_fn *saved_make_request_fn;
 
@@ -275,6 +282,7 @@ static int (*_inits[])(void) __initdata = {
 	dm_target_init,
 	dm_linear_init,
 	dm_stripe_init,
+	dm_io_init,
 	dm_kcopyd_init,
 	dm_interface_init,
 };
@@ -284,6 +292,7 @@ static void (*_exits[])(void) = {
 	dm_target_exit,
 	dm_linear_exit,
 	dm_stripe_exit,
+	dm_io_exit,
 	dm_kcopyd_exit,
 	dm_interface_exit,
 };
@@ -320,6 +329,11 @@ static void __exit dm_exit(void)
 /*
  * Block device functions
  */
+int dm_deleting_md(struct mapped_device *md)
+{
+	return test_bit(DMF_DELETING, &md->flags);
+}
+
 static int dm_blk_open(struct block_device *bdev, fmode_t mode)
 {
 	struct mapped_device *md;
@@ -331,7 +345,7 @@ static int dm_blk_open(struct block_device *bdev, fmode_t mode)
 		goto out;
 
 	if (test_bit(DMF_FREEING, &md->flags) ||
-	    test_bit(DMF_DELETING, &md->flags)) {
+	    dm_deleting_md(md)) {
 		md = NULL;
 		goto out;
 	}
@@ -388,7 +402,7 @@ static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
 			unsigned int cmd, unsigned long arg)
 {
 	struct mapped_device *md = bdev->bd_disk->private_data;
-	struct dm_table *map = dm_get_table(md);
+	struct dm_table *map = dm_get_live_table(md);
 	struct dm_target *tgt;
 	int r = -ENOTTY;
 
@@ -401,7 +415,7 @@ static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
 
 	tgt = dm_table_get_target(map, 0);
 
-	if (dm_suspended(md)) {
+	if (dm_suspended_md(md)) {
 		r = -EAGAIN;
 		goto out;
 	}
@@ -430,9 +444,10 @@ static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
 	mempool_free(tio, md->tio_pool);
 }
 
-static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md)
+static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
+					    gfp_t gfp_mask)
 {
-	return mempool_alloc(md->tio_pool, GFP_ATOMIC);
+	return mempool_alloc(md->tio_pool, gfp_mask);
 }
 
 static void free_rq_tio(struct dm_rq_target_io *tio)
@@ -450,6 +465,12 @@ static void free_bio_info(struct dm_rq_clone_bio_info *info)
 	mempool_free(info, info->tio->md->io_pool);
 }
 
+static int md_in_flight(struct mapped_device *md)
+{
+	return atomic_read(&md->pending[READ]) +
+	       atomic_read(&md->pending[WRITE]);
+}
+
 static void start_io_acct(struct dm_io *io)
 {
 	struct mapped_device *md = io->md;
@@ -512,7 +533,7 @@ static void queue_io(struct mapped_device *md, struct bio *bio)
  * function to access the md->map field, and make sure they call
  * dm_table_put() when finished.
  */
-struct dm_table *dm_get_table(struct mapped_device *md)
+struct dm_table *dm_get_live_table(struct mapped_device *md)
 {
 	struct dm_table *t;
 	unsigned long flags;
@@ -716,28 +737,38 @@ static void end_clone_bio(struct bio *clone, int error)
 	blk_update_request(tio->orig, 0, nr_bytes);
 }
 
+static void store_barrier_error(struct mapped_device *md, int error)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&md->barrier_error_lock, flags);
+	/*
+	 * Basically, the first error is taken, but:
+	 *   -EOPNOTSUPP supersedes any I/O error.
+	 *   Requeue request supersedes any I/O error but -EOPNOTSUPP.
+	 */
+	if (!md->barrier_error || error == -EOPNOTSUPP ||
+	    (md->barrier_error != -EOPNOTSUPP &&
+	     error == DM_ENDIO_REQUEUE))
+		md->barrier_error = error;
+	spin_unlock_irqrestore(&md->barrier_error_lock, flags);
+}
+
 /*
  * 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 run_queue)
+static void rq_completed(struct mapped_device *md, int rw, int run_queue)
 {
-	int wakeup_waiters = 0;
-	struct request_queue *q = md->queue;
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	if (!queue_in_flight(q))
-		wakeup_waiters = 1;
-	spin_unlock_irqrestore(q->queue_lock, flags);
+	atomic_dec(&md->pending[rw]);
 
 	/* nudge anyone waiting on suspend queue */
-	if (wakeup_waiters)
+	if (!md_in_flight(md))
 		wake_up(&md->wait);
 
 	if (run_queue)
-		blk_run_queue(q);
+		blk_run_queue(md->queue);
 
 	/*
 	 * dm_put() must be at the end of this function. See the comment above
@@ -753,6 +784,44 @@ static void free_rq_clone(struct request *clone)
 	free_rq_tio(tio);
 }
 
+/*
+ * Complete the clone and the original request.
+ * Must be called without queue lock.
+ */
+static void dm_end_request(struct request *clone, int error)
+{
+	int rw = rq_data_dir(clone);
+	int run_queue = 1;
+	bool is_barrier = blk_barrier_rq(clone);
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	struct mapped_device *md = tio->md;
+	struct request *rq = tio->orig;
+
+	if (blk_pc_request(rq) && !is_barrier) {
+		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);
+
+	if (unlikely(is_barrier)) {
+		if (unlikely(error))
+			store_barrier_error(md, error);
+		run_queue = 0;
+	} else
+		blk_end_request_all(rq, error);
+
+	rq_completed(md, rw, run_queue);
+}
+
 static void dm_unprep_request(struct request *rq)
 {
 	struct request *clone = rq->special;
@@ -768,12 +837,23 @@ static void dm_unprep_request(struct request *rq)
  */
 void dm_requeue_unmapped_request(struct request *clone)
 {
+	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;
 	struct request_queue *q = rq->q;
 	unsigned long flags;
 
+	if (unlikely(blk_barrier_rq(clone))) {
+		/*
+		 * Barrier clones share an original request.
+		 * Leave it to dm_end_request(), which handles this special
+		 * case.
+		 */
+		dm_end_request(clone, DM_ENDIO_REQUEUE);
+		return;
+	}
+
 	dm_unprep_request(rq);
 
 	spin_lock_irqsave(q->queue_lock, flags);
@@ -782,7 +862,7 @@ void dm_requeue_unmapped_request(struct request *clone)
 	blk_requeue_request(q, rq);
 	spin_unlock_irqrestore(q->queue_lock, flags);
 
-	rq_completed(md, 0);
+	rq_completed(md, rw, 0);
 }
 EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);
 
@@ -815,34 +895,28 @@ static void start_queue(struct request_queue *q)
 	spin_unlock_irqrestore(q->queue_lock, flags);
 }
 
-/*
- * Complete the clone and the original request.
- * Must be called without queue lock.
- */
-static void dm_end_request(struct request *clone, int error)
+static void dm_done(struct request *clone, int error, bool mapped)
 {
+	int r = error;
 	struct dm_rq_target_io *tio = clone->end_io_data;
-	struct mapped_device *md = tio->md;
-	struct request *rq = tio->orig;
+	dm_request_endio_fn rq_end_io = tio->ti->type->rq_end_io;
 
-	if (blk_pc_request(rq)) {
-		rq->errors = clone->errors;
-		rq->resid_len = clone->resid_len;
+	if (mapped && rq_end_io)
+		r = rq_end_io(tio->ti, clone, error, &tio->info);
 
-		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;
+	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_unmapped_request(clone);
+	else {
+		DMWARN("unimplemented target endio return value: %d", r);
+		BUG();
 	}
-
-	free_rq_clone(clone);
-
-	blk_end_request_all(rq, error);
-
-	rq_completed(md, 1);
 }
 
 /*
@@ -850,27 +924,14 @@ static void dm_end_request(struct request *clone, int error)
  */
 static void dm_softirq_done(struct request *rq)
 {
+	bool mapped = true;
 	struct request *clone = rq->completion_data;
 	struct dm_rq_target_io *tio = clone->end_io_data;
-	dm_request_endio_fn rq_end_io = tio->ti->type->rq_end_io;
-	int error = tio->error;
 
-	if (!(rq->cmd_flags & REQ_FAILED) && rq_end_io)
-		error = rq_end_io(tio->ti, clone, error, &tio->info);
+	if (rq->cmd_flags & REQ_FAILED)
+		mapped = false;
 
-	if (error <= 0)
-		/* The target wants to complete the I/O */
-		dm_end_request(clone, error);
-	else if (error == DM_ENDIO_INCOMPLETE)
-		/* The target will handle the I/O */
-		return;
-	else if (error == DM_ENDIO_REQUEUE)
-		/* The target wants to requeue the I/O */
-		dm_requeue_unmapped_request(clone);
-	else {
-		DMWARN("unimplemented target endio return value: %d", error);
-		BUG();
-	}
+	dm_done(clone, tio->error, mapped);
 }
 
 /*
@@ -882,6 +943,19 @@ static void dm_complete_request(struct request *clone, int error)
 	struct dm_rq_target_io *tio = clone->end_io_data;
 	struct request *rq = tio->orig;
 
+	if (unlikely(blk_barrier_rq(clone))) {
+		/*
+		 * Barrier clones share an original request.  So can't use
+		 * softirq_done with the original.
+		 * Pass the clone to dm_done() directly in this special case.
+		 * It is safe (even if clone->q->queue_lock is held here)
+		 * because there is no I/O dispatching during the completion
+		 * of barrier clone.
+		 */
+		dm_done(clone, error, true);
+		return;
+	}
+
 	tio->error = error;
 	rq->completion_data = clone;
 	blk_complete_request(rq);
@@ -898,6 +972,17 @@ void dm_kill_unmapped_request(struct request *clone, int error)
 	struct dm_rq_target_io *tio = clone->end_io_data;
 	struct request *rq = tio->orig;
 
+	if (unlikely(blk_barrier_rq(clone))) {
+		/*
+		 * Barrier clones share an original request.
+		 * Leave it to dm_end_request(), which handles this special
+		 * case.
+		 */
+		BUG_ON(error > 0);
+		dm_end_request(clone, error);
+		return;
+	}
+
 	rq->cmd_flags |= REQ_FAILED;
 	dm_complete_request(clone, error);
 }
@@ -1214,7 +1299,7 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
 	struct clone_info ci;
 	int error = 0;
 
-	ci.map = dm_get_table(md);
+	ci.map = dm_get_live_table(md);
 	if (unlikely(!ci.map)) {
 		if (!bio_rw_flagged(bio, BIO_RW_BARRIER))
 			bio_io_error(bio);
@@ -1255,7 +1340,7 @@ static int dm_merge_bvec(struct request_queue *q,
 			 struct bio_vec *biovec)
 {
 	struct mapped_device *md = q->queuedata;
-	struct dm_table *map = dm_get_table(md);
+	struct dm_table *map = dm_get_live_table(md);
 	struct dm_target *ti;
 	sector_t max_sectors;
 	int max_size = 0;
@@ -1352,11 +1437,6 @@ static int dm_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct mapped_device *md = q->queuedata;
 
-	if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
-		bio_endio(bio, -EOPNOTSUPP);
-		return 0;
-	}
-
 	return md->saved_make_request_fn(q, bio); /* call __make_request() */
 }
 
@@ -1375,6 +1455,25 @@ static int dm_request(struct request_queue *q, struct bio *bio)
 	return _dm_request(q, bio);
 }
 
+/*
+ * Mark this request as flush request, so that dm_request_fn() can
+ * recognize.
+ */
+static void dm_rq_prepare_flush(struct request_queue *q, struct request *rq)
+{
+	rq->cmd_type = REQ_TYPE_LINUX_BLOCK;
+	rq->cmd[0] = REQ_LB_OP_FLUSH;
+}
+
+static bool dm_rq_is_flush_request(struct request *rq)
+{
+	if (rq->cmd_type == REQ_TYPE_LINUX_BLOCK &&
+	    rq->cmd[0] == REQ_LB_OP_FLUSH)
+		return true;
+	else
+		return false;
+}
+
 void dm_dispatch_request(struct request *rq)
 {
 	int r;
@@ -1420,25 +1519,54 @@ static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
 static int setup_clone(struct request *clone, struct request *rq,
 		       struct dm_rq_target_io *tio)
 {
-	int r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
-				  dm_rq_bio_constructor, tio);
+	int r;
 
-	if (r)
-		return r;
+	if (dm_rq_is_flush_request(rq)) {
+		blk_rq_init(NULL, clone);
+		clone->cmd_type = REQ_TYPE_FS;
+		clone->cmd_flags |= (REQ_HARDBARRIER | WRITE);
+	} else {
+		r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
+				      dm_rq_bio_constructor, tio);
+		if (r)
+			return r;
+
+		clone->cmd = rq->cmd;
+		clone->cmd_len = rq->cmd_len;
+		clone->sense = rq->sense;
+		clone->buffer = rq->buffer;
+	}
 
-	clone->cmd = rq->cmd;
-	clone->cmd_len = rq->cmd_len;
-	clone->sense = rq->sense;
-	clone->buffer = rq->buffer;
 	clone->end_io = end_clone_request;
 	clone->end_io_data = tio;
 
 	return 0;
 }
 
-static int dm_rq_flush_suspending(struct mapped_device *md)
+static struct request *clone_rq(struct request *rq, struct mapped_device *md,
+				gfp_t gfp_mask)
 {
-	return !md->suspend_rq.special;
+	struct request *clone;
+	struct dm_rq_target_io *tio;
+
+	tio = alloc_rq_tio(md, gfp_mask);
+	if (!tio)
+		return NULL;
+
+	tio->md = md;
+	tio->ti = NULL;
+	tio->orig = rq;
+	tio->error = 0;
+	memset(&tio->info, 0, sizeof(tio->info));
+
+	clone = &tio->clone;
+	if (setup_clone(clone, rq, tio)) {
+		/* -ENOMEM */
+		free_rq_tio(tio);
+		return NULL;
+	}
+
+	return clone;
 }
 
 /*
@@ -1447,39 +1575,19 @@ static int dm_rq_flush_suspending(struct mapped_device *md)
 static int dm_prep_fn(struct request_queue *q, struct request *rq)
 {
 	struct mapped_device *md = q->queuedata;
-	struct dm_rq_target_io *tio;
 	struct request *clone;
 
-	if (unlikely(rq == &md->suspend_rq)) {
-		if (dm_rq_flush_suspending(md))
-			return BLKPREP_OK;
-		else
-			/* The flush suspend was interrupted */
-			return BLKPREP_KILL;
-	}
+	if (unlikely(dm_rq_is_flush_request(rq)))
+		return BLKPREP_OK;
 
 	if (unlikely(rq->special)) {
 		DMWARN("Already has something in rq->special.");
 		return BLKPREP_KILL;
 	}
 
-	tio = alloc_rq_tio(md); /* Only one for each original request */
-	if (!tio)
-		/* -ENOMEM */
-		return BLKPREP_DEFER;
-
-	tio->md = md;
-	tio->ti = NULL;
-	tio->orig = rq;
-	tio->error = 0;
-	memset(&tio->info, 0, sizeof(tio->info));
-
-	clone = &tio->clone;
-	if (setup_clone(clone, rq, tio)) {
-		/* -ENOMEM */
-		free_rq_tio(tio);
+	clone = clone_rq(rq, md, GFP_ATOMIC);
+	if (!clone)
 		return BLKPREP_DEFER;
-	}
 
 	rq->special = clone;
 	rq->cmd_flags |= REQ_DONTPREP;
@@ -1487,11 +1595,10 @@ static int dm_prep_fn(struct request_queue *q, struct request *rq)
 	return BLKPREP_OK;
 }
 
-static void map_request(struct dm_target *ti, struct request *rq,
+static void map_request(struct dm_target *ti, struct request *clone,
 			struct mapped_device *md)
 {
 	int r;
-	struct request *clone = rq->special;
 	struct dm_rq_target_io *tio = clone->end_io_data;
 
 	/*
@@ -1511,6 +1618,8 @@ static void map_request(struct dm_target *ti, struct request *rq,
 		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(tio->orig));
 		dm_dispatch_request(clone);
 		break;
 	case DM_MAPIO_REQUEUE:
@@ -1536,29 +1645,26 @@ static void map_request(struct dm_target *ti, struct request *rq,
 static void dm_request_fn(struct request_queue *q)
 {
 	struct mapped_device *md = q->queuedata;
-	struct dm_table *map = dm_get_table(md);
+	struct dm_table *map = dm_get_live_table(md);
 	struct dm_target *ti;
-	struct request *rq;
+	struct request *rq, *clone;
 
 	/*
-	 * For noflush suspend, check blk_queue_stopped() to immediately
-	 * quit I/O dispatching.
+	 * 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_plugged(q) && !blk_queue_stopped(q)) {
 		rq = blk_peek_request(q);
 		if (!rq)
 			goto plug_and_out;
 
-		if (unlikely(rq == &md->suspend_rq)) { /* Flush suspend maker */
-			if (queue_in_flight(q))
-				/* Not quiet yet.  Wait more */
-				goto plug_and_out;
-
-			/* This device should be quiet now */
-			__stop_queue(q);
+		if (unlikely(dm_rq_is_flush_request(rq))) {
+			BUG_ON(md->flush_request);
+			md->flush_request = rq;
 			blk_start_request(rq);
-			__blk_end_request_all(rq, 0);
-			wake_up(&md->wait);
+			queue_work(md->wq, &md->barrier_work);
 			goto out;
 		}
 
@@ -1567,8 +1673,11 @@ static void dm_request_fn(struct request_queue *q)
 			goto plug_and_out;
 
 		blk_start_request(rq);
+		clone = rq->special;
+		atomic_inc(&md->pending[rq_data_dir(clone)]);
+
 		spin_unlock(q->queue_lock);
-		map_request(ti, rq, md);
+		map_request(ti, clone, md);
 		spin_lock_irq(q->queue_lock);
 	}
 
@@ -1595,7 +1704,7 @@ static int dm_lld_busy(struct request_queue *q)
 {
 	int r;
 	struct mapped_device *md = q->queuedata;
-	struct dm_table *map = dm_get_table(md);
+	struct dm_table *map = dm_get_live_table(md);
 
 	if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
 		r = 1;
@@ -1610,7 +1719,7 @@ static int dm_lld_busy(struct request_queue *q)
 static void dm_unplug_all(struct request_queue *q)
 {
 	struct mapped_device *md = q->queuedata;
-	struct dm_table *map = dm_get_table(md);
+	struct dm_table *map = dm_get_live_table(md);
 
 	if (map) {
 		if (dm_request_based(md))
@@ -1628,7 +1737,7 @@ static int dm_any_congested(void *congested_data, int bdi_bits)
 	struct dm_table *map;
 
 	if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
-		map = dm_get_table(md);
+		map = dm_get_live_table(md);
 		if (map) {
 			/*
 			 * Request-based dm cares about only own queue for
@@ -1725,6 +1834,7 @@ out:
 static const struct block_device_operations dm_blk_dops;
 
 static void dm_wq_work(struct work_struct *work);
+static void dm_rq_barrier_work(struct work_struct *work);
 
 /*
  * Allocate and initialise a blank device with a given minor.
@@ -1754,6 +1864,7 @@ static struct mapped_device *alloc_dev(int minor)
 	init_rwsem(&md->io_lock);
 	mutex_init(&md->suspend_lock);
 	spin_lock_init(&md->deferred_lock);
+	spin_lock_init(&md->barrier_error_lock);
 	rwlock_init(&md->map_lock);
 	atomic_set(&md->holders, 1);
 	atomic_set(&md->open_count, 0);
@@ -1788,6 +1899,8 @@ static struct mapped_device *alloc_dev(int minor)
 	blk_queue_softirq_done(md->queue, dm_softirq_done);
 	blk_queue_prep_rq(md->queue, dm_prep_fn);
 	blk_queue_lld_busy(md->queue, dm_lld_busy);
+	blk_queue_ordered(md->queue, QUEUE_ORDERED_DRAIN_FLUSH,
+			  dm_rq_prepare_flush);
 
 	md->disk = alloc_disk(1);
 	if (!md->disk)
@@ -1797,6 +1910,7 @@ static struct mapped_device *alloc_dev(int minor)
 	atomic_set(&md->pending[1], 0);
 	init_waitqueue_head(&md->wait);
 	INIT_WORK(&md->work, dm_wq_work);
+	INIT_WORK(&md->barrier_work, dm_rq_barrier_work);
 	init_waitqueue_head(&md->eventq);
 
 	md->disk->major = _major;
@@ -1921,9 +2035,13 @@ static void __set_size(struct mapped_device *md, sector_t size)
 	mutex_unlock(&md->bdev->bd_inode->i_mutex);
 }
 
-static int __bind(struct mapped_device *md, struct dm_table *t,
-		  struct queue_limits *limits)
+/*
+ * Returns old map, which caller must destroy.
+ */
+static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
+			       struct queue_limits *limits)
 {
+	struct dm_table *old_map;
 	struct request_queue *q = md->queue;
 	sector_t size;
 	unsigned long flags;
@@ -1938,11 +2056,6 @@ static int __bind(struct mapped_device *md, struct dm_table *t,
 
 	__set_size(md, size);
 
-	if (!size) {
-		dm_table_destroy(t);
-		return 0;
-	}
-
 	dm_table_event_callback(t, event_callback, md);
 
 	/*
@@ -1958,26 +2071,31 @@ static int __bind(struct mapped_device *md, struct dm_table *t,
 	__bind_mempools(md, t);
 
 	write_lock_irqsave(&md->map_lock, flags);
+	old_map = md->map;
 	md->map = t;
 	dm_table_set_restrictions(t, q, limits);
 	write_unlock_irqrestore(&md->map_lock, flags);
 
-	return 0;
+	return old_map;
 }
 
-static void __unbind(struct mapped_device *md)
+/*
+ * Returns unbound table for the caller to free.
+ */
+static struct dm_table *__unbind(struct mapped_device *md)
 {
 	struct dm_table *map = md->map;
 	unsigned long flags;
 
 	if (!map)
-		return;
+		return NULL;
 
 	dm_table_event_callback(map, NULL, NULL);
 	write_lock_irqsave(&md->map_lock, flags);
 	md->map = NULL;
 	write_unlock_irqrestore(&md->map_lock, flags);
-	dm_table_destroy(map);
+
+	return map;
 }
 
 /*
@@ -2059,18 +2177,18 @@ void dm_put(struct mapped_device *md)
 	BUG_ON(test_bit(DMF_FREEING, &md->flags));
 
 	if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
-		map = dm_get_table(md);
+		map = dm_get_live_table(md);
 		idr_replace(&_minor_idr, MINOR_ALLOCED,
 			    MINOR(disk_devt(dm_disk(md))));
 		set_bit(DMF_FREEING, &md->flags);
 		spin_unlock(&_minor_lock);
-		if (!dm_suspended(md)) {
+		if (!dm_suspended_md(md)) {
 			dm_table_presuspend_targets(map);
 			dm_table_postsuspend_targets(map);
 		}
 		dm_sysfs_exit(md);
 		dm_table_put(map);
-		__unbind(md);
+		dm_table_destroy(__unbind(md));
 		free_dev(md);
 	}
 }
@@ -2080,8 +2198,6 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
 {
 	int r = 0;
 	DECLARE_WAITQUEUE(wait, current);
-	struct request_queue *q = md->queue;
-	unsigned long flags;
 
 	dm_unplug_all(md->queue);
 
@@ -2091,15 +2207,7 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
 		set_current_state(interruptible);
 
 		smp_mb();
-		if (dm_request_based(md)) {
-			spin_lock_irqsave(q->queue_lock, flags);
-			if (!queue_in_flight(q) && blk_queue_stopped(q)) {
-				spin_unlock_irqrestore(q->queue_lock, flags);
-				break;
-			}
-			spin_unlock_irqrestore(q->queue_lock, flags);
-		} else if (!atomic_read(&md->pending[0]) &&
-					!atomic_read(&md->pending[1]))
+		if (!md_in_flight(md))
 			break;
 
 		if (interruptible == TASK_INTERRUPTIBLE &&
@@ -2194,98 +2302,106 @@ static void dm_queue_flush(struct mapped_device *md)
 	queue_work(md->wq, &md->work);
 }
 
-/*
- * Swap in a new table (destroying old one).
- */
-int dm_swap_table(struct mapped_device *md, struct dm_table *table)
+static void dm_rq_set_flush_nr(struct request *clone, unsigned flush_nr)
 {
-	struct queue_limits limits;
-	int r = -EINVAL;
+	struct dm_rq_target_io *tio = clone->end_io_data;
 
-	mutex_lock(&md->suspend_lock);
+	tio->info.flush_request = flush_nr;
+}
 
-	/* device must be suspended */
-	if (!dm_suspended(md))
-		goto out;
+/* Issue barrier requests to targets and wait for their completion. */
+static int dm_rq_barrier(struct mapped_device *md)
+{
+	int i, j;
+	struct dm_table *map = dm_get_live_table(md);
+	unsigned num_targets = dm_table_get_num_targets(map);
+	struct dm_target *ti;
+	struct request *clone;
 
-	r = dm_calculate_queue_limits(table, &limits);
-	if (r)
-		goto out;
+	md->barrier_error = 0;
 
-	/* cannot change the device type, once a table is bound */
-	if (md->map &&
-	    (dm_table_get_type(md->map) != dm_table_get_type(table))) {
-		DMWARN("can't change the device type after a table is bound");
-		goto out;
+	for (i = 0; i < num_targets; i++) {
+		ti = dm_table_get_target(map, i);
+		for (j = 0; j < ti->num_flush_requests; j++) {
+			clone = clone_rq(md->flush_request, md, GFP_NOIO);
+			dm_rq_set_flush_nr(clone, j);
+			atomic_inc(&md->pending[rq_data_dir(clone)]);
+			map_request(ti, clone, md);
+		}
 	}
 
-	__unbind(md);
-	r = __bind(md, table, &limits);
-
-out:
-	mutex_unlock(&md->suspend_lock);
-	return r;
-}
+	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
+	dm_table_put(map);
 
-static void dm_rq_invalidate_suspend_marker(struct mapped_device *md)
-{
-	md->suspend_rq.special = (void *)0x1;
+	return md->barrier_error;
 }
 
-static void dm_rq_abort_suspend(struct mapped_device *md, int noflush)
+static void dm_rq_barrier_work(struct work_struct *work)
 {
+	int error;
+	struct mapped_device *md = container_of(work, struct mapped_device,
+						barrier_work);
 	struct request_queue *q = md->queue;
+	struct request *rq;
 	unsigned long flags;
 
-	spin_lock_irqsave(q->queue_lock, flags);
-	if (!noflush)
-		dm_rq_invalidate_suspend_marker(md);
-	__start_queue(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
+	/*
+	 * Hold the md reference here and leave it at the last part so that
+	 * the md can't be deleted by device opener when the barrier request
+	 * completes.
+	 */
+	dm_get(md);
 
-static void dm_rq_start_suspend(struct mapped_device *md, int noflush)
-{
-	struct request *rq = &md->suspend_rq;
-	struct request_queue *q = md->queue;
+	error = dm_rq_barrier(md);
 
-	if (noflush)
-		stop_queue(q);
-	else {
-		blk_rq_init(q, rq);
-		blk_insert_request(q, rq, 0, NULL);
-	}
+	rq = md->flush_request;
+	md->flush_request = NULL;
+
+	if (error == DM_ENDIO_REQUEUE) {
+		spin_lock_irqsave(q->queue_lock, flags);
+		blk_requeue_request(q, rq);
+		spin_unlock_irqrestore(q->queue_lock, flags);
+	} else
+		blk_end_request_all(rq, error);
+
+	blk_run_queue(q);
+
+	dm_put(md);
 }
 
-static int dm_rq_suspend_available(struct mapped_device *md, int noflush)
+/*
+ * Swap in a new table, returning the old one for the caller to destroy.
+ */
+struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
 {
-	int r = 1;
-	struct request *rq = &md->suspend_rq;
-	struct request_queue *q = md->queue;
-	unsigned long flags;
+	struct dm_table *map = ERR_PTR(-EINVAL);
+	struct queue_limits limits;
+	int r;
 
-	if (noflush)
-		return r;
+	mutex_lock(&md->suspend_lock);
 
-	/* The marker must be protected by queue lock if it is in use */
-	spin_lock_irqsave(q->queue_lock, flags);
-	if (unlikely(rq->ref_count)) {
-		/*
-		 * This can happen, when the previous flush suspend was
-		 * interrupted, the marker is still in the queue and
-		 * this flush suspend has been invoked, because we don't
-		 * remove the marker at the time of suspend interruption.
-		 * We have only one marker per mapped_device, so we can't
-		 * start another flush suspend while it is in use.
-		 */
-		BUG_ON(!rq->special); /* The marker should be invalidated */
-		DMWARN("Invalidating the previous flush suspend is still in"
-		       " progress.  Please retry later.");
-		r = 0;
+	/* device must be suspended */
+	if (!dm_suspended_md(md))
+		goto out;
+
+	r = dm_calculate_queue_limits(table, &limits);
+	if (r) {
+		map = ERR_PTR(r);
+		goto out;
 	}
-	spin_unlock_irqrestore(q->queue_lock, flags);
 
-	return r;
+	/* cannot change the device type, once a table is bound */
+	if (md->map &&
+	    (dm_table_get_type(md->map) != dm_table_get_type(table))) {
+		DMWARN("can't change the device type after a table is bound");
+		goto out;
+	}
+
+	map = __bind(md, table, &limits);
+
+out:
+	mutex_unlock(&md->suspend_lock);
+	return map;
 }
 
 /*
@@ -2330,49 +2446,11 @@ static void unlock_fs(struct mapped_device *md)
 /*
  * Suspend mechanism in request-based dm.
  *
- * After the suspend starts, further incoming requests are kept in
- * the request_queue and deferred.
- * Remaining requests in the request_queue at the start of suspend are flushed
- * if it is flush suspend.
- * The suspend completes when the following conditions have been satisfied,
- * so wait for it:
- *    1. q->in_flight is 0 (which means no in_flight request)
- *    2. queue has been stopped (which means no request dispatching)
- *
+ * 1. Flush all I/Os by lock_fs() if needed.
+ * 2. Stop dispatching any I/O by stopping the request_queue.
+ * 3. Wait for all in-flight I/Os to be completed or requeued.
  *
- * Noflush suspend
- * ---------------
- * Noflush suspend doesn't need to dispatch remaining requests.
- * So stop the queue immediately.  Then, wait for all in_flight requests
- * to be completed or requeued.
- *
- * To abort noflush suspend, start the queue.
- *
- *
- * Flush suspend
- * -------------
- * Flush suspend needs to dispatch remaining requests.  So stop the queue
- * after the remaining requests are completed. (Requeued request must be also
- * re-dispatched and completed.  Until then, we can't stop the queue.)
- *
- * During flushing the remaining requests, further incoming requests are also
- * inserted to the same queue.  To distinguish which requests are to be
- * flushed, we insert a marker request to the queue at the time of starting
- * flush suspend, like a barrier.
- * The dispatching is blocked when the marker is found on the top of the queue.
- * And the queue is stopped when all in_flight requests are completed, since
- * that means the remaining requests are completely flushed.
- * Then, the marker is removed from the queue.
- *
- * To abort flush suspend, we also need to take care of the marker, not only
- * starting the queue.
- * We don't remove the marker forcibly from the queue since it's against
- * the block-layer manner.  Instead, we put a invalidated mark on the marker.
- * When the invalidated marker is found on the top of the queue, it is
- * immediately removed from the queue, so it doesn't block dispatching.
- * Because we have only one marker per mapped_device, we can't start another
- * flush suspend until the invalidated marker is removed from the queue.
- * So fail and return with -EBUSY in such a case.
+ * To abort suspend, start the request_queue.
  */
 int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 {
@@ -2383,17 +2461,12 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 
 	mutex_lock(&md->suspend_lock);
 
-	if (dm_suspended(md)) {
+	if (dm_suspended_md(md)) {
 		r = -EINVAL;
 		goto out_unlock;
 	}
 
-	if (dm_request_based(md) && !dm_rq_suspend_available(md, noflush)) {
-		r = -EBUSY;
-		goto out_unlock;
-	}
-
-	map = dm_get_table(md);
+	map = dm_get_live_table(md);
 
 	/*
 	 * DMF_NOFLUSH_SUSPENDING must be set before presuspend.
@@ -2406,8 +2479,10 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 	dm_table_presuspend_targets(map);
 
 	/*
-	 * Flush I/O to the device. noflush supersedes do_lockfs,
-	 * because lock_fs() needs to flush I/Os.
+	 * Flush I/O to the device.
+	 * Any I/O submitted after lock_fs() may not be flushed.
+	 * noflush takes precedence over do_lockfs.
+	 * (lock_fs() flushes I/Os and waits for them to complete.)
 	 */
 	if (!noflush && do_lockfs) {
 		r = lock_fs(md);
@@ -2436,10 +2511,15 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 	set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
 	up_write(&md->io_lock);
 
-	flush_workqueue(md->wq);
-
+	/*
+	 * Request-based dm uses md->wq for barrier (dm_rq_barrier_work) which
+	 * can be kicked until md->queue is stopped.  So stop md->queue before
+	 * flushing md->wq.
+	 */
 	if (dm_request_based(md))
-		dm_rq_start_suspend(md, noflush);
+		stop_queue(md->queue);
+
+	flush_workqueue(md->wq);
 
 	/*
 	 * At this point no more requests are entering target request routines.
@@ -2458,7 +2538,7 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 		dm_queue_flush(md);
 
 		if (dm_request_based(md))
-			dm_rq_abort_suspend(md, noflush);
+			start_queue(md->queue);
 
 		unlock_fs(md);
 		goto out; /* pushback list is already flushed, so skip flush */
@@ -2470,10 +2550,10 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 	 * requests are being added to md->deferred list.
 	 */
 
-	dm_table_postsuspend_targets(map);
-
 	set_bit(DMF_SUSPENDED, &md->flags);
 
+	dm_table_postsuspend_targets(map);
+
 out:
 	dm_table_put(map);
 
@@ -2488,10 +2568,10 @@ int dm_resume(struct mapped_device *md)
 	struct dm_table *map = NULL;
 
 	mutex_lock(&md->suspend_lock);
-	if (!dm_suspended(md))
+	if (!dm_suspended_md(md))
 		goto out;
 
-	map = dm_get_table(md);
+	map = dm_get_live_table(md);
 	if (!map || !dm_table_get_size(map))
 		goto out;
 
@@ -2592,18 +2672,29 @@ struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
 		return NULL;
 
 	if (test_bit(DMF_FREEING, &md->flags) ||
-	    test_bit(DMF_DELETING, &md->flags))
+	    dm_deleting_md(md))
 		return NULL;
 
 	dm_get(md);
 	return md;
 }
 
-int dm_suspended(struct mapped_device *md)
+int dm_suspended_md(struct mapped_device *md)
 {
 	return test_bit(DMF_SUSPENDED, &md->flags);
 }
 
+int dm_suspended(struct dm_target *ti)
+{
+	struct mapped_device *md = dm_table_get_md(ti->table);
+	int r = dm_suspended_md(md);
+
+	dm_put(md);
+
+	return r;
+}
+EXPORT_SYMBOL_GPL(dm_suspended);
+
 int dm_noflush_suspending(struct dm_target *ti)
 {
 	struct mapped_device *md = dm_table_get_md(ti->table);