This sequence:
# truncate --size=65536 fsfile
# losetup --offset 65536 /dev/loop0 fsfile
# mkfs.ext4 /dev/loop0
# losetup -d /dev/loop0
# mount -o loop,ro,offset=65536 fsfile mnt/
# umount mnt
# dmesg | tail
results in an IO error when unmounting the RO filesystem:
[ 312.386074] SELinux: initialized (dev loop1, type ext4), uses xattr
[ 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 behavior changed with:
commit 24bcc89c7e7c64982e6192b4952a0a92379fc341
Author: Jan Kara <jack@xxxxxxx>
Date: Tue Mar 13 15:41:04 2012 -0400
jbd2: split updating of journal superblock and marking journal empty
which lost some of the magic in jbd2_journal_update_superblock() which
used to test for a journal with no outstanding transactions.
I'm not sure if the following is quite the right approach, but it fixes
it for me.
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
p.s. no idea why this only happens if I use a loop device with an offset!
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index e9a3c4c..987ec76 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1354,6 +1354,11 @@ static void jbd2_mark_journal_empty(journal_t *journal)
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);
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
