1 files changed, 142 insertions, 57 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 788ba96a6256..8a994be035ba 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -89,12 +89,13 @@ union map_info *dm_get_mapinfo(struct bio *bio)
 /*
  * Bits for the md->flags field.
  */
-#define DMF_BLOCK_IO 0
+#define DMF_BLOCK_IO_FOR_SUSPEND 0
 #define DMF_SUSPENDED 1
 #define DMF_FROZEN 2
 #define DMF_FREEING 3
 #define DMF_DELETING 4
 #define DMF_NOFLUSH_SUSPENDING 5
+#define DMF_QUEUE_IO_TO_THREAD 6
 
 /*
  * Work processed by per-device workqueue.
@@ -124,6 +125,11 @@ struct mapped_device {
         spinlock_t deferred_lock;
 
         /*
+         * An error from the barrier request currently being processed.
+         */
+        int barrier_error;
+
+        /*
          * Processing queue (flush/barriers)
          */
         struct workqueue_struct *wq;
@@ -424,6 +430,10 @@ static void end_io_acct(struct dm_io *io)
         part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
         part_stat_unlock();
 
+        /*
+         * After this is decremented the bio must not be touched if it is
+         * a barrier.
+         */
         dm_disk(md)->part0.in_flight = pending =
                 atomic_dec_return(&md->pending);
 
@@ -435,21 +445,18 @@ static void end_io_acct(struct dm_io *io)
 /*
  * Add the bio to the list of deferred io.
  */
-static int queue_io(struct mapped_device *md, struct bio *bio)
+static void queue_io(struct mapped_device *md, struct bio *bio)
 {
         down_write(&md->io_lock);
 
-        if (!test_bit(DMF_BLOCK_IO, &md->flags)) {
-                up_write(&md->io_lock);
-                return 1;
-        }
-
         spin_lock_irq(&md->deferred_lock);
         bio_list_add(&md->deferred, bio);
         spin_unlock_irq(&md->deferred_lock);
 
+        if (!test_and_set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags))
+                queue_work(md->wq, &md->work);
+
         up_write(&md->io_lock);
-        return 0;               /* deferred successfully */
 }
 
 /*
@@ -533,25 +540,35 @@ static void dec_pending(struct dm_io *io, int error)
                          */
                         spin_lock_irqsave(&md->deferred_lock, flags);
                         if (__noflush_suspending(md))
-                                bio_list_add(&md->deferred, io->bio);
+                                bio_list_add_head(&md->deferred, io->bio);
                         else
                                 /* noflush suspend was interrupted. */
                                 io->error = -EIO;
                         spin_unlock_irqrestore(&md->deferred_lock, flags);
                 }
 
-                end_io_acct(io);
-
                 io_error = io->error;
                 bio = io->bio;
 
-                free_io(md, io);
+                if (bio_barrier(bio)) {
+                        /*
+                         * There can be just one barrier request so we use
+                         * a per-device variable for error reporting.
+                         * Note that you can't touch the bio after end_io_acct
+                         */
+                        md->barrier_error = io_error;
+                        end_io_acct(io);
+                } else {
+                        end_io_acct(io);
 
-                if (io_error != DM_ENDIO_REQUEUE) {
-                        trace_block_bio_complete(md->queue, bio);
+                        if (io_error != DM_ENDIO_REQUEUE) {
+                                trace_block_bio_complete(md->queue, bio);
 
-                        bio_endio(bio, io_error);
+                                bio_endio(bio, io_error);
+                        }
                 }
+
+                free_io(md, io);
         }
 }
 
@@ -693,13 +710,19 @@ static struct bio *split_bvec(struct bio *bio, sector_t sector,
 
         clone->bi_sector = sector;
         clone->bi_bdev = bio->bi_bdev;
-        clone->bi_rw = bio->bi_rw;
+        clone->bi_rw = bio->bi_rw & ~(1 << BIO_RW_BARRIER);
         clone->bi_vcnt = 1;
         clone->bi_size = to_bytes(len);
         clone->bi_io_vec->bv_offset = offset;
         clone->bi_io_vec->bv_len = clone->bi_size;
         clone->bi_flags |= 1 << BIO_CLONED;
 
+        if (bio_integrity(bio)) {
+                bio_integrity_clone(clone, bio, GFP_NOIO);
+                bio_integrity_trim(clone,
+                                   bio_sector_offset(bio, idx, offset), len);
+        }
+
         return clone;
 }
 
@@ -714,6 +737,7 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector,
 
         clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
         __bio_clone(clone, bio);
+        clone->bi_rw &= ~(1 << BIO_RW_BARRIER);
         clone->bi_destructor = dm_bio_destructor;
         clone->bi_sector = sector;
         clone->bi_idx = idx;
@@ -721,6 +745,14 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector,
         clone->bi_size = to_bytes(len);
         clone->bi_flags &= ~(1 << BIO_SEG_VALID);
 
+        if (bio_integrity(bio)) {
+                bio_integrity_clone(clone, bio, GFP_NOIO);
+
+                if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
+                        bio_integrity_trim(clone,
+                                           bio_sector_offset(bio, idx, 0), len);
+        }
+
         return clone;
 }
 
@@ -834,14 +866,13 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
 
         ci.map = dm_get_table(md);
         if (unlikely(!ci.map)) {
-                bio_io_error(bio);
-                return;
-        }
-        if (unlikely(bio_barrier(bio) && !dm_table_barrier_ok(ci.map))) {
-                dm_table_put(ci.map);
-                bio_endio(bio, -EOPNOTSUPP);
+                if (!bio_barrier(bio))
+                        bio_io_error(bio);
+                else
+                        md->barrier_error = -EIO;
                 return;
         }
+
         ci.md = md;
         ci.bio = bio;
         ci.io = alloc_io(md);
@@ -918,7 +949,6 @@ out:
  */
 static int dm_request(struct request_queue *q, struct bio *bio)
 {
-        int r = -EIO;
         int rw = bio_data_dir(bio);
         struct mapped_device *md = q->queuedata;
         int cpu;
@@ -931,34 +961,27 @@ static int dm_request(struct request_queue *q, struct bio *bio)
         part_stat_unlock();
 
         /*
-         * If we're suspended we have to queue
-         * this io for later.
+         * If we're suspended or the thread is processing barriers
+         * we have to queue this io for later.
          */
-        while (test_bit(DMF_BLOCK_IO, &md->flags)) {
+        if (unlikely(test_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags)) ||
+            unlikely(bio_barrier(bio))) {
                 up_read(&md->io_lock);
 
-                if (bio_rw(bio) != READA)
-                        r = queue_io(md, bio);
+                if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) &&
+                    bio_rw(bio) == READA) {
+                        bio_io_error(bio);
+                        return 0;
+                }
 
-                if (r <= 0)
-                        goto out_req;
+                queue_io(md, bio);
 
-                /*
-                 * We're in a while loop, because someone could suspend
-                 * before we get to the following read lock.
-                 */
-                down_read(&md->io_lock);
+                return 0;
         }
 
         __split_and_process_bio(md, bio);
         up_read(&md->io_lock);
         return 0;
-
-out_req:
-        if (r < 0)
-                bio_io_error(bio);
-
-        return 0;
 }
 
 static void dm_unplug_all(struct request_queue *q)
@@ -978,7 +1001,7 @@ static int dm_any_congested(void *congested_data, int bdi_bits)
         struct mapped_device *md = congested_data;
         struct dm_table *map;
 
-        if (!test_bit(DMF_BLOCK_IO, &md->flags)) {
+        if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
                 map = dm_get_table(md);
                 if (map) {
                         r = dm_table_any_congested(map, bdi_bits);
@@ -1193,6 +1216,7 @@ static void free_dev(struct mapped_device *md)
         mempool_destroy(md->tio_pool);
         mempool_destroy(md->io_pool);
         bioset_free(md->bs);
+        blk_integrity_unregister(md->disk);
         del_gendisk(md->disk);
         free_minor(minor);
 
@@ -1406,6 +1430,36 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
         return r;
 }
 
+static int dm_flush(struct mapped_device *md)
+{
+        dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
+        return 0;
+}
+
+static void process_barrier(struct mapped_device *md, struct bio *bio)
+{
+        int error = dm_flush(md);
+
+        if (unlikely(error)) {
+                bio_endio(bio, error);
+                return;
+        }
+        if (bio_empty_barrier(bio)) {
+                bio_endio(bio, 0);
+                return;
+        }
+
+        __split_and_process_bio(md, bio);
+
+        error = dm_flush(md);
+
+        if (!error && md->barrier_error)
+                error = md->barrier_error;
+
+        if (md->barrier_error != DM_ENDIO_REQUEUE)
+                bio_endio(bio, error);
+}
+
 /*
  * Process the deferred bios
  */
@@ -1417,25 +1471,34 @@ static void dm_wq_work(struct work_struct *work)
 
         down_write(&md->io_lock);
 
-next_bio:
-        spin_lock_irq(&md->deferred_lock);
-        c = bio_list_pop(&md->deferred);
-        spin_unlock_irq(&md->deferred_lock);
+        while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
+                spin_lock_irq(&md->deferred_lock);
+                c = bio_list_pop(&md->deferred);
+                spin_unlock_irq(&md->deferred_lock);
 
-        if (c) {
-                __split_and_process_bio(md, c);
-                goto next_bio;
-        }
+                if (!c) {
+                        clear_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
+                        break;
+                }
 
-        clear_bit(DMF_BLOCK_IO, &md->flags);
+                up_write(&md->io_lock);
+
+                if (bio_barrier(c))
+                        process_barrier(md, c);
+                else
+                        __split_and_process_bio(md, c);
+
+                down_write(&md->io_lock);
+        }
 
         up_write(&md->io_lock);
 }
 
 static void dm_queue_flush(struct mapped_device *md)
 {
+        clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+        smp_mb__after_clear_bit();
         queue_work(md->wq, &md->work);
-        flush_workqueue(md->wq);
 }
 
 /*
@@ -1553,20 +1616,36 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
         }
 
         /*
-         * First we set the BLOCK_IO flag so no more ios will be mapped.
+         * Here we must make sure that no processes are submitting requests
+         * to target drivers i.e. no one may be executing
+         * __split_and_process_bio. This is called from dm_request and
+         * dm_wq_work.
+         *
+         * To get all processes out of __split_and_process_bio in dm_request,
+         * we take the write lock. To prevent any process from reentering
+         * __split_and_process_bio from dm_request, we set
+         * DMF_QUEUE_IO_TO_THREAD.
+         *
+         * To quiesce the thread (dm_wq_work), we set DMF_BLOCK_IO_FOR_SUSPEND
+         * and call flush_workqueue(md->wq). flush_workqueue will wait until
+         * dm_wq_work exits and DMF_BLOCK_IO_FOR_SUSPEND will prevent any
+         * further calls to __split_and_process_bio from dm_wq_work.
          */
         down_write(&md->io_lock);
-        set_bit(DMF_BLOCK_IO, &md->flags);
-
+        set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+        set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
         up_write(&md->io_lock);
 
+        flush_workqueue(md->wq);
+
         /*
-         * Wait for the already-mapped ios to complete.
+         * At this point no more requests are entering target request routines.
+         * We call dm_wait_for_completion to wait for all existing requests
+         * to finish.
          */
         r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
 
         down_write(&md->io_lock);
-
         if (noflush)
                 clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
         up_write(&md->io_lock);
@@ -1579,6 +1658,12 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
                 goto out; /* pushback list is already flushed, so skip flush */
         }
 
+        /*
+         * If dm_wait_for_completion returned 0, the device is completely
+         * quiescent now. There is no request-processing activity. All new
+         * requests are being added to md->deferred list.
+         */
+
         dm_table_postsuspend_targets(map);
 
         set_bit(DMF_SUSPENDED, &md->flags);