From: Jeff Mahoney <jeffm@suse.com>
Subject: [PATCH] ext3: always mark super uptodate before dirty
References: bnc#457043
Patch-mainline: not yet

 The superblock's bh is something of an exception. It is only read
 during mount and is only released during unmount. The in-memory
 copy is invariably the most recent one.

 If a write error occurs while syncing the superblock, it will be marked
 !uptodate. When another error occurs, ext3_error will invoke
 ext3_commit_super, which will mark the superblock dirty and try to
 sync it out again. If the buffer is !uptodate, then mark_buffer_dirty
 will issue a warning, but continue anyway.

 This patch marks it uptodate before writing it out. This doesn't really
 change anything other than silencing the warning in mark_buffer_dirty.
 If the write succeeds, good. Otherwise, it will just have uptodate
 cleared again.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
---
 fs/ext3/super.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2382,6 +2382,13 @@ static int ext3_commit_super(struct supe
 	es->s_free_blocks_count = cpu_to_le32(ext3_count_free_blocks(sb));
 	es->s_free_inodes_count = cpu_to_le32(ext3_count_free_inodes(sb));
 	BUFFER_TRACE(sbh, "marking dirty");
+
+	/* We only read the superblock once. The in-memory version is
+	 * always the most recent. If ext3_error is called after a
+	 * superblock write failure, it will be !uptodate. This write
+	 * will likely fail also, but it avoids the WARN_ON in
+	 * mark_buffer_dirty. */
+	set_buffer_uptodate(sbh);
 	mark_buffer_dirty(sbh);
 	if (sync)
 		error = sync_dirty_buffer(sbh);
