ext4: write superblock only once on unmount

In some rather rare cases it is possible that ext4 may the superblock
to the media twice. This patch makes sure this does not happen. This
should speed up unmounting in those cases.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 1e26f4a0b555574e3eb680e2c9222106b4042810..626c1f840118cc8853d50ec200385f6147f7f32d 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -836,9 +836,6 @@ static void ext4_put_super(struct super_block *sb)
        destroy_workqueue(sbi->dio_unwritten_wq);
 
        lock_super(sb);
-       if (sb->s_dirt)
-               ext4_commit_super(sb, 1);
-
        if (sbi->s_journal) {
                err = jbd2_journal_destroy(sbi->s_journal);
                sbi->s_journal = NULL;
@@ -855,8 +852,10 @@ static void ext4_put_super(struct super_block *sb)
        if (!(sb->s_flags & MS_RDONLY)) {
                EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
                es->s_state = cpu_to_le16(sbi->s_mount_state);
-               ext4_commit_super(sb, 1);
        }
+       if (sb->s_dirt || !(sb->s_flags & MS_RDONLY))
+               ext4_commit_super(sb, 1);
+
        if (sbi->s_proc) {
                remove_proc_entry("options", sbi->s_proc);
                remove_proc_entry(sb->s_id, ext4_proc_root);