diff options
author | Hannes Reinecke <hare@suse.de> | 2013-07-10 22:41:15 (GMT) |
---|---|---|
committer | Alasdair G Kergon <agk@redhat.com> | 2013-07-10 22:41:15 (GMT) |
commit | 6c182cd88d179cbbd06f4f8a8a19b6977940753f (patch) | |
tree | 27971aeafbdd2410699e77477565157c67d8ffea | |
parent | 8bb495e3f02401ee6f76d1b1d77f3ac9f079e376 (diff) | |
download | linux-6c182cd88d179cbbd06f4f8a8a19b6977940753f.tar.xz |
dm mpath: fix ioctl deadlock when no paths
When multipath needs to retry an ioctl the reference to the
current live table needs to be dropped. Otherwise a deadlock
occurs when all paths are down:
- dm_blk_ioctl takes a reference to the current table
and spins in multipath_ioctl().
- A new table is being loaded, but upon resume the process
hangs in dm_table_destroy() waiting for references to
drop to zero.
With this patch the reference to the old table is dropped
prior to retry, thereby avoiding the deadlock.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r-- | drivers/md/dm-mpath.c | 8 | ||||
-rw-r--r-- | drivers/md/dm.c | 9 |
2 files changed, 10 insertions, 7 deletions
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index bdf26f5..5adede1 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -1561,7 +1561,6 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long flags; int r; -again: bdev = NULL; mode = 0; r = 0; @@ -1579,7 +1578,7 @@ again: } if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path)) - r = -EAGAIN; + r = -ENOTCONN; else if (!bdev) r = -EIO; @@ -1591,11 +1590,8 @@ again: if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT) r = scsi_verify_blk_ioctl(NULL, cmd); - if (r == -EAGAIN && !fatal_signal_pending(current)) { + if (r == -ENOTCONN && !fatal_signal_pending(current)) queue_work(kmultipathd, &m->process_queued_ios); - msleep(10); - goto again; - } return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg); } diff --git a/drivers/md/dm.c b/drivers/md/dm.c index d5370a9..33f2010 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -386,10 +386,12 @@ static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg) { struct mapped_device *md = bdev->bd_disk->private_data; - struct dm_table *map = dm_get_live_table(md); + struct dm_table *map; struct dm_target *tgt; int r = -ENOTTY; +retry: + map = dm_get_live_table(md); if (!map || !dm_table_get_size(map)) goto out; @@ -410,6 +412,11 @@ static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode, out: dm_table_put(map); + if (r == -ENOTCONN) { + msleep(10); + goto retry; + } + return r; } |