dm: disable barriers

This patch causes device-mapper to reject any barrier requests.  This is done
since most of the targets won't handle this correctly anyway.  So until the
situation improves it is better to reject these requests at the first place.
Since barrier requests won't get to the targets, the checks there can be
removed.

Cc: stable@kernel.org
Signed-off-by: Stefan Bader <shbader@de.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index ece7c7c4cdbb99c30aee196124a9487be8cceb80..ba952a032598c2411bb3f7ff793f6d00baec92bc 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -941,9 +941,6 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
        struct crypt_config *cc = ti->private;
        struct dm_crypt_io *io;
 
-       if (bio_barrier(bio))
-               return -EOPNOTSUPP;
-
        io = mempool_alloc(cc->io_pool, GFP_NOIO);
        io->target = ti;
        io->base_bio = bio;

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index fc6c1021178df2504293b558c2a2088acc46a65c..d6ca9d0a6fd1cbd5fd8f223e9e2b901092e631f3 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -798,9 +798,6 @@ static int multipath_map(struct dm_target *ti, struct bio *bio,
        struct dm_mpath_io *mpio;
        struct multipath *m = (struct multipath *) ti->private;
 
-       if (bio_barrier(bio))
-               return -EOPNOTSUPP;
-
        mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
        dm_bio_record(&mpio->details, bio);
 

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 854891d07b59a5e5049267988d94748f18524f35..83ddbfe6b8a415ca492c2db7b4701c1492a2a623 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -889,9 +889,6 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
        if (!s->valid)
                return -EIO;
 
-       if (unlikely(bio_barrier(bio)))
-               return -EOPNOTSUPP;
-
        /* FIXME: should only take write lock if we need
         * to copy an exception */
        down_write(&s->lock);
@@ -1162,9 +1159,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
        struct dm_dev *dev = ti->private;
        bio->bi_bdev = dev->bdev;
 
-       if (unlikely(bio_barrier(bio)))
-               return -EOPNOTSUPP;
-
        /* Only tell snapshots if this is a write */
        return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED;
 }

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b5e56af8f85ac039a296445027d404f80f3dd9ba..f4f7d35561ab83753f03fe16a186514514916bf6 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -800,6 +800,15 @@ static int dm_request(request_queue_t *q, struct bio *bio)
        int rw = bio_data_dir(bio);
        struct mapped_device *md = q->queuedata;
 
+       /*
+        * There is no use in forwarding any barrier request since we can't
+        * guarantee it is (or can be) handled by the targets correctly.
+        */
+       if (unlikely(bio_barrier(bio))) {
+               bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
+               return 0;
+       }
+
        down_read(&md->io_lock);
 
        disk_stat_inc(dm_disk(md), ios[rw]);