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Re: [PATCH 4/6] xfs: zeroing space needs to punch delalloc blocks

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH 4/6] xfs: zeroing space needs to punch delalloc blocks
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Thu, 10 Apr 2014 22:22:59 +1000
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20140410104001.GG17641@xxxxxxxxxxxxx>
References: <1397106053-7489-1-git-send-email-david@xxxxxxxxxxxxx> <1397106053-7489-5-git-send-email-david@xxxxxxxxxxxxx> <20140410104001.GG17641@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Thu, Apr 10, 2014 at 03:40:01AM -0700, Christoph Hellwig wrote:
> On Thu, Apr 10, 2014 at 03:00:51PM +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@xxxxxxxxxx>
> > 
> > When we are zeroing space andit is covered by a delalloc range, we
> > need to punch the delalloc range out before we truncate the page
> > cache. Failing to do so leaves and inconsistency between the page
> > cache and the extent tree, which we later trip over when doing
> > direct IO over the same range.
> 
> Looks good.
> 
> Which test found this?

The fsstress tests - any of them will do. It showed after I merged
Lukas' FALLOC_FL_ZERO_RANGE support patches for fsstress and fsx
into xfstests, but it wasn't reliably triggering until I fixed the
__xfs_get_blocks DIO bug that Al found...

> > @@ -1432,9 +1434,18 @@ xfs_zero_file_space(
> >     ASSERT(end_boundary <= offset + len);
> >  
> >     if (start_boundary < end_boundary - 1) {
> > -           /* punch out the page cache over the conversion range */
> > +           /*
> > +            * punch out delayed allocation blocks and the page cache over
> > +            * the conversion range
> > +            */
> > +           xfs_ilock(ip, XFS_ILOCK_EXCL);
> > +           error = xfs_bmap_punch_delalloc_range(ip,
> > +                           XFS_B_TO_FSB(mp, start_boundary),
> 
> Shouldn't this be XFS_B_TO_FSBT?

XFS_B_TO_FSB gives the same result given that we've already rounded
start_boundary to block granularity....

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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