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authorHannes Reinecke <hare@suse.de>2013-07-10 23:41:15 +0100
committerAlasdair G Kergon <agk@redhat.com>2013-07-10 23:41:15 +0100
commit6c182cd88d179cbbd06f4f8a8a19b6977940753f (patch)
tree27971aeafbdd2410699e77477565157c67d8ffea
parent8bb495e3f02401ee6f76d1b1d77f3ac9f079e376 (diff)
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.c8
-rw-r--r--drivers/md/dm.c9
2 files changed, 10 insertions, 7 deletions
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index bdf26f5bd326..5adede17ddf6 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 d5370a94b2c1..33f20103d8d5 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;
}