btrfs: add helper function find_fsid_by_disk

In preparation for adding support to mount multiple single-disk
btrfs filesystems with the same FSID, wrap find_fsid() into
find_fsid_by_disk().

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 790368d4b866bacaccced70fcbe84cda98c3ff82..44fd866772e2afae16c769fe8ef264fab303a4e1 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -553,6 +553,20 @@ static int btrfs_free_stale_devices(dev_t devt, struct btrfs_device *skip_device
        return ret;
 }
 
+static struct btrfs_fs_devices *find_fsid_by_device(
+                                       struct btrfs_super_block *disk_super)
+{
+       struct btrfs_fs_devices *fsid_fs_devices;
+       const bool has_metadata_uuid = (btrfs_super_incompat_flags(disk_super) &
+                                       BTRFS_FEATURE_INCOMPAT_METADATA_UUID);
+
+       /* Find the fs_device by the usual method, if found use it. */
+       fsid_fs_devices = find_fsid(disk_super->fsid,
+                   has_metadata_uuid ? disk_super->metadata_uuid : NULL);
+
+       return fsid_fs_devices;
+}
+
 /*
  * This is only used on mount, and we are protected from competing things
  * messing with our fs_devices by the uuid_mutex, thus we do not need the
@@ -673,10 +687,7 @@ static noinline struct btrfs_device *device_list_add(const char *path,
                return ERR_PTR(error);
        }
 
-       if (has_metadata_uuid)
-               fs_devices = find_fsid(disk_super->fsid, disk_super->metadata_uuid);
-       else
-               fs_devices = find_fsid(disk_super->fsid, NULL);
+       fs_devices = find_fsid_by_device(disk_super);
 
        if (!fs_devices) {
                fs_devices = alloc_fs_devices(disk_super->fsid);