Btrfs: Only open block devices once during mount -o subvol=

btrfs_open_devices needed a check to see if the device was already
open.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 55da5f0c56e3..aa001b08ced0 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -196,6 +196,9 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
         mutex_lock(&uuid_mutex);
         list_for_each(cur, head) {
                 device = list_entry(cur, struct btrfs_device, dev_list);
+                if (device->bdev)
+                        continue;
+
                 bdev = open_bdev_excl(device->name, flags, holder);
 
                 if (IS_ERR(bdev)) {