ext4: use ext4_group_desc_free() in ext4_put_super() to save some duplicated code

The only difference here is that ->s_group_desc and ->s_flex_groups share
the same rcu read lock here but it is not necessary. In other places they
do not share the lock at all.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-4-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -1226,11 +1226,23 @@ static void ext4_percpu_param_destroy(struct ext4_sb_info *sbi)
 	percpu_free_rwsem(&sbi->s_writepages_rwsem);
 }
 
+static void ext4_group_desc_free(struct ext4_sb_info *sbi)
+{
+	struct buffer_head **group_desc;
+	int i;
+
+	rcu_read_lock();
+	group_desc = rcu_dereference(sbi->s_group_desc);
+	for (i = 0; i < sbi->s_gdb_count; i++)
+		brelse(group_desc[i]);
+	kvfree(group_desc);
+	rcu_read_unlock();
+}
+
 static void ext4_put_super(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct ext4_super_block *es = sbi->s_es;
-	struct buffer_head **group_desc;
 	struct flex_groups **flex_groups;
 	int aborted = 0;
 	int i, err;
@@ -1281,11 +1293,8 @@ static void ext4_put_super(struct super_block *sb)
 	if (!sb_rdonly(sb))
 		ext4_commit_super(sb);
 
+	ext4_group_desc_free(sbi);
 	rcu_read_lock();
-	group_desc = rcu_dereference(sbi->s_group_desc);
-	for (i = 0; i < sbi->s_gdb_count; i++)
-		brelse(group_desc[i]);
-	kvfree(group_desc);
 	flex_groups = rcu_dereference(sbi->s_flex_groups);
 	if (flex_groups) {
 		for (i = 0; i < sbi->s_flex_groups_allocated; i++)
@@ -4757,19 +4766,6 @@ static int ext4_geometry_check(struct super_block *sb,
 	return 0;
 }
 
-static void ext4_group_desc_free(struct ext4_sb_info *sbi)
-{
-	struct buffer_head **group_desc;
-	int i;
-
-	rcu_read_lock();
-	group_desc = rcu_dereference(sbi->s_group_desc);
-	for (i = 0; i < sbi->s_gdb_count; i++)
-		brelse(group_desc[i]);
-	kvfree(group_desc);
-	rcu_read_unlock();
-}
-
 static int ext4_group_desc_init(struct super_block *sb,
 				struct ext4_super_block *es,
 				ext4_fsblk_t logical_sb_block,