Commit 07a83c47 authored by Stefan Bader's avatar Stefan Bader Committed by Linus Torvalds
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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

Signed-off-by: default avatarStefan Bader <>
Signed-off-by: default avatarAlasdair G Kergon <>
Signed-off-by: default avatarLinus Torvalds <>
parent 943317ef
......@@ -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))
io = mempool_alloc(cc->io_pool, GFP_NOIO);
io->target = ti;
io->base_bio = bio;
......@@ -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))
mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
dm_bio_record(&mpio->details, bio);
......@@ -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)))
/* FIXME: should only take write lock if we need
* to copy an exception */
......@@ -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)))
/* Only tell snapshots if this is a write */
return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED;
......@@ -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;
disk_stat_inc(dm_disk(md), ios[rw]);
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