From: Mikulas Patocka Date: Thu, 10 Dec 2009 23:51:53 +0000 (+0000) Subject: dm snapshot: only take lock for statustype info not table X-Git-Tag: v2.6.32.2~51 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=5f5d50a0f5530e5a6df52755c74ec5a47829f8cc;p=karo-tx-linux.git dm snapshot: only take lock for statustype info not table commit 94e76572b5dd37b1f0f4b3742ee8a565daead932 upstream. Take snapshot lock only for STATUSTYPE_INFO, not STATUSTYPE_TABLE. Commit 4c6fff445d7aa753957856278d4d93bcad6e2c14 (dm-snapshot-lock-snapshot-while-supplying-status.patch) introduced this use of the lock, but userspace applications using libdevmapper have been found to request STATUSTYPE_TABLE while the device is suspended and the lock is already held, leading to deadlock. Since the lock is not necessary in this case, don't try to take it. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 3a3ba46e6d4b..d135212958f1 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1152,10 +1152,11 @@ static int snapshot_status(struct dm_target *ti, status_type_t type, unsigned sz = 0; struct dm_snapshot *snap = ti->private; - down_write(&snap->lock); - switch (type) { case STATUSTYPE_INFO: + + down_write(&snap->lock); + if (!snap->valid) DMEMIT("Invalid"); else { @@ -1171,6 +1172,9 @@ static int snapshot_status(struct dm_target *ti, status_type_t type, else DMEMIT("Unknown"); } + + up_write(&snap->lock); + break; case STATUSTYPE_TABLE: @@ -1185,8 +1189,6 @@ static int snapshot_status(struct dm_target *ti, status_type_t type, break; } - up_write(&snap->lock); - return 0; }