btrfs: simplify how changed fsid and metadata_uuid is checked

We often check if the metadata_uuid is not the same as fsid, and then we
check if the given fsid matches the metadata_uuid. This patch refactors
this logic into function match_fsid_changed and utilize it.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -457,6 +457,19 @@ static noinline struct btrfs_fs_devices *find_fsid(
 	return NULL;
 }
 
+/*
+ * First check if the metadata_uuid is different from the fsid in the given
+ * fs_devices. Then check if the given fsid is the same as the metadata_uuid
+ * in the fs_devices. If it is, return true; otherwise, return false.
+ */
+static inline bool check_fsid_changed(const struct btrfs_fs_devices *fs_devices,
+				      const u8 *fsid)
+{
+	return memcmp(fs_devices->fsid, fs_devices->metadata_uuid,
+		      BTRFS_FSID_SIZE) != 0 &&
+	       memcmp(fs_devices->metadata_uuid, fsid, BTRFS_FSID_SIZE) == 0;
+}
+
 static struct btrfs_fs_devices *find_fsid_with_metadata_uuid(
 				struct btrfs_super_block *disk_super)
 {
@@ -485,14 +498,12 @@ static struct btrfs_fs_devices *find_fsid_with_metadata_uuid(
 	 * CHANGING_FSID_V2 flag set.
 	 */
 	list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
-		if (fs_devices->fsid_change &&
-		    memcmp(fs_devices->metadata_uuid,
-			   fs_devices->fsid, BTRFS_FSID_SIZE) != 0 &&
-		    memcmp(disk_super->metadata_uuid, fs_devices->metadata_uuid,
-			   BTRFS_FSID_SIZE) == 0) {
+		if (!fs_devices->fsid_change)
+			continue;
+
+		if (check_fsid_changed(fs_devices, disk_super->metadata_uuid))
 			return fs_devices;
 	}
-	}
 
 	return find_fsid(disk_super->fsid, disk_super->metadata_uuid);
 }
@@ -682,18 +693,16 @@ static struct btrfs_fs_devices *find_fsid_inprogress(
 	struct btrfs_fs_devices *fs_devices;
 
 	list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
-		if (memcmp(fs_devices->metadata_uuid, fs_devices->fsid,
-			   BTRFS_FSID_SIZE) != 0 &&
-		    memcmp(fs_devices->metadata_uuid, disk_super->fsid,
-			   BTRFS_FSID_SIZE) == 0 && !fs_devices->fsid_change) {
+		if (fs_devices->fsid_change)
+			continue;
+
+		if (check_fsid_changed(fs_devices,  disk_super->fsid))
 			return fs_devices;
 	}
-	}
 
 	return find_fsid(disk_super->fsid, NULL);
 }
 
-
 static struct btrfs_fs_devices *find_fsid_changed(
 					struct btrfs_super_block *disk_super)
 {
@@ -710,10 +719,7 @@ static struct btrfs_fs_devices *find_fsid_changed(
 	 */
 	list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
 		/* Changed UUIDs */
-		if (memcmp(fs_devices->metadata_uuid, fs_devices->fsid,
-			   BTRFS_FSID_SIZE) != 0 &&
-		    memcmp(fs_devices->metadata_uuid, disk_super->metadata_uuid,
-			   BTRFS_FSID_SIZE) == 0 &&
+		if (check_fsid_changed(fs_devices, disk_super->metadata_uuid) &&
 		    memcmp(fs_devices->fsid, disk_super->fsid,
 			   BTRFS_FSID_SIZE) != 0)
 			return fs_devices;
@@ -744,11 +750,10 @@ static struct btrfs_fs_devices *find_fsid_reverted_metadata(
 	 * fs_devices equal to the FSID of the disk.
 	 */
 	list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
-		if (memcmp(fs_devices->fsid, fs_devices->metadata_uuid,
-			   BTRFS_FSID_SIZE) != 0 &&
-		    memcmp(fs_devices->metadata_uuid, disk_super->fsid,
-			   BTRFS_FSID_SIZE) == 0 &&
-		    fs_devices->fsid_change)
+		if (!fs_devices->fsid_change)
+			continue;
+
+		if (check_fsid_changed(fs_devices, disk_super->fsid))
 			return fs_devices;
 	}