1 files changed, 384 insertions, 289 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 724efc63904d..d21e1284604f 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;
@@ -614,8 +635,10 @@ static void dec_pending(struct dm_io *io, int error)
                         if (!md->barrier_error && io_error != -EOPNOTSUPP)
                                 md->barrier_error = io_error;
                         end_io_acct(io);
+                        free_io(md, io);
                 } else {
                         end_io_acct(io);
+                        free_io(md, io);
 
                         if (io_error != DM_ENDIO_REQUEUE) {
                                 trace_block_bio_complete(md->queue, bio);
@@ -623,8 +646,6 @@ static void dec_pending(struct dm_io *io, int error)
                                 bio_endio(bio, io_error);
                         }
                 }
-
-                free_io(md, io);
         }
 }
 
@@ -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;
 }
 
 /*
@@ -1447,51 +1575,35 @@ 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 */
+        clone = clone_rq(rq, md, GFP_ATOMIC);
+        if (!clone)
                 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);
-                return BLKPREP_DEFER;
-        }
-
         rq->special = clone;
         rq->cmd_flags |= REQ_DONTPREP;
 
         return BLKPREP_OK;
 }
 
-static void map_request(struct dm_target *ti, struct request *rq,
-                        struct mapped_device *md)
+/*
+ * Returns:
+ * 0  : the request has been processed (not requeued)
+ * !0 : the request has been requeued
+ */
+static int map_request(struct dm_target *ti, struct request *clone,
+                       struct mapped_device *md)
 {
-        int r;
-        struct request *clone = rq->special;
+        int r, requeued = 0;
         struct dm_rq_target_io *tio = clone->end_io_data;
 
         /*
@@ -1511,11 +1623,14 @@ 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:
                 /* The target wants to requeue the I/O */
                 dm_requeue_unmapped_request(clone);
+                requeued = 1;
                 break;
         default:
                 if (r > 0) {
@@ -1527,6 +1642,8 @@ static void map_request(struct dm_target *ti, struct request *rq,
                 dm_kill_unmapped_request(clone, r);
                 break;
         }
+
+        return requeued;
 }
 
 /*
@@ -1536,29 +1653,26 @@ 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;
                 }
 
@@ -1567,13 +1681,21 @@ 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);
+                if (map_request(ti, clone, md))
+                        goto requeued;
+
                 spin_lock_irq(q->queue_lock);
         }
 
         goto out;
 
+requeued:
+        spin_lock_irq(q->queue_lock);
+
 plug_and_out:
         if (!elv_queue_empty(q))
                 /* Some requests still remain, retry later */
@@ -1595,7 +1717,7 @@ 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 +1732,7 @@ 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 +1750,7 @@ 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 +1847,7 @@ 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 +1877,7 @@ 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 +1912,8 @@ 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 +1923,7 @@ 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 +2048,13 @@ 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 +2069,6 @@ 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 +2084,31 @@ 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 +2190,18 @@ 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 +2211,6 @@ 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 +2220,7 @@ 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 +2315,106 @@ 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 +2459,11 @@ 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 +2474,12 @@ 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 +2492,10 @@ 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 +2524,15 @@ 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 +2551,7 @@ 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 +2563,10 @@ 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 +2581,10 @@ 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;
 
@@ -2525,18 +2618,19 @@ out:
 /*-----------------------------------------------------------------
  * Event notification.
  *---------------------------------------------------------------*/
-void dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
+int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
                        unsigned cookie)
 {
         char udev_cookie[DM_COOKIE_LENGTH];
         char *envp[] = { udev_cookie, NULL };
 
         if (!cookie)
-                kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
+                return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
         else {
                 snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
                          DM_COOKIE_ENV_VAR_NAME, cookie);
-                kobject_uevent_env(&disk_to_dev(md->disk)->kobj, action, envp);
+                return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
+                                          action, envp);
         }
 }
 
@@ -2592,26 +2686,27 @@ 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_noflush_suspending(struct dm_target *ti)
+int dm_suspended(struct dm_target *ti)
 {
-        struct mapped_device *md = dm_table_get_md(ti->table);
-        int r = __noflush_suspending(md);
-
-        dm_put(md);
+        return dm_suspended_md(dm_table_get_md(ti->table));
+}
+EXPORT_SYMBOL_GPL(dm_suspended);
 
-        return r;
+int dm_noflush_suspending(struct dm_target *ti)
+{
+        return __noflush_suspending(dm_table_get_md(ti->table));
 }
 EXPORT_SYMBOL_GPL(dm_noflush_suspending);