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>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index be3ad7ce86d2d3fea6f19ab6fb0c856a174cebc9..45e1c314369e263626636ed6238b4e9af85ada2b 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -943,9 +943,6 @@ 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 de54b39e6ffe9fb78cbad18c2a5d5b559d54d870..bfb2ea3037b6689055e04cd14476d848ae56d413 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 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 2717a355dc5bf6847243de88f78fd540da5e941b..75bd2fd8575e12418db71bf2f15a49c6e1b3a096 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]);