On Wed 18-08-10 05:29:17, Christoph Hellwig wrote:
> Switch to the WRITE_FLUSH_FUA flag for journal commits and remove the
> EOPNOTSUPP detection for barriers.
  Well, in the context of just this patch series, the patch is OK so you
can add
  Acked-by: Jan Kara <jack@suse.cz>
But as soon as blkdev_issue_flush() stops draining the queue, commit when
JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT is set breaks. Do you plan to fix
that separately? Actually, attached is a patch which should fix
ASYNC_COMMIT code... The patch is totally untested, I just wrote it
because it's simpler than explaining what needs to be done ;).

								Honza
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Index: linux-2.6/fs/jbd2/commit.c
> ===================================================================
> --- linux-2.6.orig/fs/jbd2/commit.c	2010-08-17 16:52:37.111011684 +0200
> +++ linux-2.6/fs/jbd2/commit.c	2010-08-17 16:53:50.531029420 +0200
> @@ -134,25 +134,10 @@ static int journal_submit_commit_record(
>  
>  	if (journal->j_flags & JBD2_BARRIER &&
>  	    !JBD2_HAS_INCOMPAT_FEATURE(journal,
> -				       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
> -		ret = submit_bh(WRITE_SYNC_PLUG | WRITE_BARRIER, bh);
> -		if (ret == -EOPNOTSUPP) {
> -			printk(KERN_WARNING
> -			       "JBD: barrier-based sync failed on %s - "
> -			       "disabling barriers\n", journal->j_devname);
> -			spin_lock(&journal->j_state_lock);
> -			journal->j_flags &= ~JBD2_BARRIER;
> -			spin_unlock(&journal->j_state_lock);
> -
> -			/* And try again, without the barrier */
> -			lock_buffer(bh);
> -			set_buffer_uptodate(bh);
> -			clear_buffer_dirty(bh);
> -			ret = submit_bh(WRITE_SYNC_PLUG, bh);
> -		}
> -	} else {
> +				       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT))
> +		ret = submit_bh(WRITE_SYNC_PLUG | WRITE_FLUSH_FUA, bh);
> +	else
>  		ret = submit_bh(WRITE_SYNC_PLUG, bh);
> -	}
>  
>  	*cbh = bh;
>  	return ret;
> @@ -167,29 +152,8 @@ static int journal_wait_on_commit_record
>  {
>  	int ret = 0;
>  
> -retry:
>  	clear_buffer_dirty(bh);
>  	wait_on_buffer(bh);
> -	if (buffer_eopnotsupp(bh) && (journal->j_flags & JBD2_BARRIER)) {
> -		printk(KERN_WARNING
> -		       "JBD2: wait_on_commit_record: sync failed on %s - "
> -		       "disabling barriers\n", journal->j_devname);
> -		spin_lock(&journal->j_state_lock);
> -		journal->j_flags &= ~JBD2_BARRIER;
> -		spin_unlock(&journal->j_state_lock);
> -
> -		lock_buffer(bh);
> -		clear_buffer_dirty(bh);
> -		set_buffer_uptodate(bh);
> -		bh->b_end_io = journal_end_buffer_io_sync;
> -
> -		ret = submit_bh(WRITE_SYNC_PLUG, bh);
> -		if (ret) {
> -			unlock_buffer(bh);
> -			return ret;
> -		}
> -		goto retry;
> -	}
>  
>  	if (unlikely(!buffer_uptodate(bh)))
>  		ret = -EIO;
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR