btrfs: simplify fsid and metadata_uuid comparisons

Refactor the functions find_fsid() and find_fsid_with_metadata_uuid(),
as they currently share a common set of code to compare the fsid and
metadata_uuid. Create a common helper function, match_fsid_fs_devices().

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 de60a55..1affe63 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -427,6 +427,21 @@ void __exit btrfs_cleanup_fs_uuids(void)
        }
 }
 
+static bool match_fsid_fs_devices(const struct btrfs_fs_devices *fs_devices,
+                                 const u8 *fsid, const u8 *metadata_fsid)
+{
+       if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) != 0)
+               return false;
+
+       if (!metadata_fsid)
+               return true;
+
+       if (memcmp(metadata_fsid, fs_devices->metadata_uuid, BTRFS_FSID_SIZE) != 0)
+               return false;
+
+       return true;
+}
+
 static noinline struct btrfs_fs_devices *find_fsid(
                const u8 *fsid, const u8 *metadata_fsid)
 {
@@ -436,15 +451,8 @@ static noinline struct btrfs_fs_devices *find_fsid(
 
        /* Handle non-split brain cases */
        list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
-               if (metadata_fsid) {
-                       if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0
-                           && memcmp(metadata_fsid, fs_devices->metadata_uuid,
-                                     BTRFS_FSID_SIZE) == 0)
-                               return fs_devices;
-               } else {
-                       if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0)
-                               return fs_devices;
-               }
+               if (match_fsid_fs_devices(fs_devices, fsid, metadata_fsid))
+                       return fs_devices;
        }
        return NULL;
 }
@@ -462,14 +470,14 @@ static struct btrfs_fs_devices *find_fsid_with_metadata_uuid(
         * at all and the CHANGING_FSID_V2 flag set.
         */
        list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
-               if (fs_devices->fsid_change &&
-                   memcmp(disk_super->metadata_uuid, fs_devices->fsid,
-                          BTRFS_FSID_SIZE) == 0 &&
-                   memcmp(fs_devices->fsid, fs_devices->metadata_uuid,
-                          BTRFS_FSID_SIZE) == 0) {
+               if (!fs_devices->fsid_change)
+                       continue;
+
+               if (match_fsid_fs_devices(fs_devices, disk_super->metadata_uuid,
+                                         fs_devices->fsid))
                        return fs_devices;
-               }
        }
+
        /*
         * Handle scanned device having completed its fsid change but
         * belonging to a fs_devices that was created by a device that