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authorMikulas Patocka <mpatocka@redhat.com>2009-12-10 23:51:53 +0000
committerAlasdair G Kergon <agk@redhat.com>2009-12-10 23:51:53 +0000
commit94e76572b5dd37b1f0f4b3742ee8a565daead932 (patch)
tree2e7737f21d99a881b7a2d0977adad1d2bd9bfb87
parentd2bb7df8cac647b92f51fb84ae735771e7adbfa7 (diff)
downloadlinux-94e76572b5dd37b1f0f4b3742ee8a565daead932.tar.bz2
dm snapshot: only take lock for statustype info not table
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. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-snap.c10
1 files changed, 6 insertions, 4 deletions
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;
}