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>

1 files changed, 3 insertions, 4 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 1e26f4a0b555..626c1f840118 100644
--- 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);