On Tue 28-05-13 13:18:59, Dmitry Monakhov wrote:
> Inode's data or non journaled quota may be written w/o jounral so we must
> send a barrier at the end of ext3_sync_fs. But it can be skipped if journal
> commit will do it for us.
>
> changes from v1:
> skip barrier for async mode
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
> ---
> fs/ext3/super.c | 12 ++++++++----
> 1 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> index fb5120a..c8a4e17 100644
> --- a/fs/ext3/super.c
> +++ b/fs/ext3/super.c
> @@ -2521,6 +2521,7 @@ int ext3_force_commit(struct super_block *sb)
> static int ext3_sync_fs(struct super_block *sb, int wait)
> {
> tid_t target;
> + int ret = 0;
>
> trace_ext3_sync_fs(sb, wait);
> /*
> @@ -2528,11 +2529,14 @@ static int ext3_sync_fs(struct super_block *sb, int wait)
> * no dirty dquots
> */
> dquot_writeback_dquots(sb, -1);
> - if (journal_start_commit(EXT3_SB(sb)->s_journal, &target)) {
> - if (wait)
> - log_wait_commit(EXT3_SB(sb)->s_journal, target);
> + if (wait) {
> + if (journal_start_commit(EXT3_SB(sb)->s_journal, &target))
> + ret = log_wait_commit(EXT3_SB(sb)->s_journal, target);
> + else
> + ret = blkdev_issue_flush(sb->s_bdev, GFP_KERNEL, NULL);
> }
> - return 0;
> +
> + return ret;
> }
This will issue a flush even if the filesystem is mounted with barrier=0.
That's not good. Also journal_start_commit() was deliberately called even
if wait == 0. This is so that journal commit is started and in a not so
rare case where second sync pass doesn't find anything to write, we can
just wait for an already running commit...
Finally I think it may be actually worth it and do a similar thing as you
did for ext4/jbd2 with the latest transaction in the journal. It's not very
intrusive change.
Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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