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authorMikulas Patocka <mpatocka@redhat.com>2009-10-16 23:18:16 +0100
committerAlasdair G Kergon <agk@redhat.com>2009-10-16 23:18:16 +0100
commit4c6fff445d7aa753957856278d4d93bcad6e2c14 (patch)
tree56ac3d262699fe5a42f76fe9f992277a6a7a2934 /drivers/md/dm-snap.c
parent0e8c4e4e3ebb15756ddc4170a88149a2cd323cfe (diff)
dm snapshot: lock snapshot while supplying status
This patch locks the snapshot when returning status. It fixes a race when it could return an invalid number of free chunks if someone was simultaneously modifying it. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-snap.c')
-rw-r--r--drivers/md/dm-snap.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 9cb392b3e92..9bc814aa2bb 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1152,6 +1152,8 @@ 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:
if (!snap->valid)
@@ -1183,6 +1185,8 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
break;
}
+ up_write(&snap->lock);
+
return 0;
}