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| author | Mikulas Patocka <mpatocka@redhat.com> | 2024-09-13 15:05:18 +0200 |
|---|---|---|
| committer | Mikulas Patocka <mpatocka@redhat.com> | 2024-09-15 21:02:54 +0200 |
| commit | c8691cd0fc11197515ed148de0780d927bfca38b (patch) | |
| tree | 5ac0b3519f9bf7d5b6e69a1f74d6c645ec479eef /drivers/md | |
| parent | dm-integrity: check mac_size against HASH_MAX_DIGESTSIZE in sb_mac() (diff) | |
| download | linux-c8691cd0fc11197515ed148de0780d927bfca38b.tar.xz linux-c8691cd0fc11197515ed148de0780d927bfca38b.zip | |
Revert "dm: requeue IO if mapping table not yet available"
This reverts commit fa247089de9936a46e290d4724cb5f0b845600f5.
The following sequence of commands causes a livelock - there will be
workqueue process looping and consuming 100% CPU:
dmsetup create --notable test
truncate -s 1MiB testdata
losetup /dev/loop0 testdata
dmsetup load test --table '0 2048 linear /dev/loop0 0'
dd if=/dev/zero of=/dev/dm-0 bs=16k count=1 conv=fdatasync
The livelock is caused by the commit fa247089de99. The commit claims that
it fixes a race condition, however, it is unknown what the actual race
condition is and what program is involved in the race condition.
When the inactive table is loaded, the nodes /dev/dm-0 and
/sys/block/dm-0 are created. /dev/dm-0 has zero size at this point. When
the device is suspended and resumed, the nodes /dev/mapper/test and
/dev/disk/* are created.
If some program opens a block device before it is created by dmsetup or
lvm, the program is buggy, so dm could just report an error as it used to
do before.
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: fa247089de99 ("dm: requeue IO if mapping table not yet available")
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-rq.c | 4 | ||||
| -rw-r--r-- | drivers/md/dm.c | 11 |
2 files changed, 11 insertions, 4 deletions
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index f7e9a3632eb3..499f8cc8a39f 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -496,8 +496,10 @@ static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, map = dm_get_live_table(md, &srcu_idx); if (unlikely(!map)) { + DMERR_LIMIT("%s: mapping table unavailable, erroring io", + dm_device_name(md)); dm_put_live_table(md, srcu_idx); - return BLK_STS_RESOURCE; + return BLK_STS_IOERR; } ti = dm_table_find_target(map, 0); dm_put_live_table(md, srcu_idx); diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 87bb90303435..ff4a6b570b76 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2030,10 +2030,15 @@ static void dm_submit_bio(struct bio *bio) struct dm_table *map; map = dm_get_live_table(md, &srcu_idx); + if (unlikely(!map)) { + DMERR_LIMIT("%s: mapping table unavailable, erroring io", + dm_device_name(md)); + bio_io_error(bio); + goto out; + } - /* If suspended, or map not yet available, queue this IO for later */ - if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) || - unlikely(!map)) { + /* If suspended, queue this IO for later */ + if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) { if (bio->bi_opf & REQ_NOWAIT) bio_wouldblock_error(bio); else if (bio->bi_opf & REQ_RAHEAD) |