[PATCH] 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.

Signed-off-by: Stefan Bader <shbader@de.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 6b50991623efba106b9004ff5f521f8b17927a93..7989dac5de2115208bb1fc47ea4f0cbe25d582aa 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -940,9 +940,6 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
        struct crypt_config *cc = ti->private;
        struct 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 3aa0135069672d8fe7f3ed4c6e743d969478c95f..af27464b7edbf718a47d06f2808604ce3f60679a 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -795,9 +795,6 @@ static int multipath_map(struct dm_target *ti, struct bio *bio,
        struct 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 9227ba4f19db16ad8d36eb0da3096d9144480f0e..39556210db55bf5df014db8635412a6cc8501fa1 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -887,9 +887,6 @@ 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);
@@ -1160,9 +1157,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
        struct dm_dev *dev = (struct dm_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 3668b170ea68f7c11cb8fc850ddf1babeb7eaa5a..d531f0cb81a4bd32ee406590239cdabaa2143391 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -802,6 +802,15 @@ 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]);