[ 058/108] jbd: dont write superblock when unmounting an ro filesystem

From: Greg Kroah-Hartman
Date: Wed Sep 12 2012 - 20:29:06 EST

From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>

3.5-stable review patch. If anyone has any objections, please let me know.


From: Jan Kara <jack@xxxxxxx>

commit 2e84f2641ea91a730642ead558a4ee3bd52310c9 upstream.

This sequence:

results in an IO error when unmounting the RO filesystem. The bug was
introduced by:

commit 9754e39c7bc51328f145e933bfb0df47cd67b6e9
Author: Jan Kara <jack@xxxxxxx>
Date: Sat Apr 7 12:33:03 2012 +0200

jbd: Split updating of journal superblock and marking journal empty

which lost some of the magic in journal_update_superblock() which
used to test for a journal with no outstanding transactions.

This is a port of a jbd2 fix by Eric Sandeen.

Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/jbd/journal.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -1113,6 +1113,11 @@ static void mark_journal_empty(journal_t

+ /* Is it already empty? */
+ if (sb->s_start == 0) {
+ spin_unlock(&journal->j_state_lock);
+ return;
+ }
jbd_debug(1, "JBD: Marking journal as empty (seq %d)\n",

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/