| From eeecef0af5ea4efd763c9554cf2bd80fc4a0efd3 Mon Sep 17 00:00:00 2001 |
| From: Eric Sandeen <sandeen@redhat.com> |
| Date: Sat, 18 Aug 2012 22:29:40 -0400 |
| Subject: jbd2: don't write superblock when if its empty |
| |
| From: Eric Sandeen <sandeen@redhat.com> |
| |
| commit eeecef0af5ea4efd763c9554cf2bd80fc4a0efd3 upstream. |
| |
| This sequence: |
| |
| # truncate --size=1g fsfile |
| # mkfs.ext4 -F fsfile |
| # mount -o loop,ro fsfile /mnt |
| # umount /mnt |
| # dmesg | tail |
| |
| results in an IO error when unmounting the RO filesystem: |
| |
| [ 318.020828] Buffer I/O error on device loop1, logical block 196608 |
| [ 318.027024] lost page write due to I/O error on loop1 |
| [ 318.032088] JBD2: Error -5 detected when updating journal superblock for loop1-8. |
| |
| This was a regression introduced by commit 24bcc89c7e7c: "jbd2: split |
| updating of journal superblock and marking journal empty". |
| |
| Signed-off-by: Eric Sandeen <sandeen@redhat.com> |
| Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/jbd2/journal.c | 5 +++++ |
| 1 file changed, 5 insertions(+) |
| |
| --- a/fs/jbd2/journal.c |
| +++ b/fs/jbd2/journal.c |
| @@ -1317,6 +1317,11 @@ static void jbd2_mark_journal_empty(jour |
| |
| BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex)); |
| read_lock(&journal->j_state_lock); |
| + /* Is it already empty? */ |
| + if (sb->s_start == 0) { |
| + read_unlock(&journal->j_state_lock); |
| + return; |
| + } |
| jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n", |
| journal->j_tail_sequence); |
| |
