ext4: add missing brelse() add_new_gdb_meta_bg()'s error path

BugLink: https://bugs.launchpad.net/bugs/1810947

commit 61a9c11e upstream.

Fixes: 01f795f9 ("ext4: add online resizing support for meta_bg ...")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org # 3.7
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

fs/ext4/resize.c

@@ -899,6 +899,7 @@ static int add_new_gdb_meta_bg(struct super_block *sb,
 				     sizeof(struct buffer_head *),
 				     GFP_NOFS);
 	if (!n_group_desc) {
+		brelse(gdb_bh);
 		err = -ENOMEM;
 		ext4_warning(sb, "not enough memory for %lu groups",
 			     gdb_num + 1);
@@ -914,8 +915,6 @@ static int add_new_gdb_meta_bg(struct super_block *sb,
 	kvfree(o_group_desc);
 	BUFFER_TRACE(gdb_bh, "get_write_access");
 	err = ext4_journal_get_write_access(handle, gdb_bh);
-	if (unlikely(err))
-		brelse(gdb_bh);
 	return err;
 }