From: Dave Chinner <david@fromorbit.com>
To: Brian Foster <bfoster@redhat.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 1/4] xfs: track collapse via file offset rather than extent index
Date: Tue, 9 Sep 2014 14:03:52 +1000 [thread overview]
Message-ID: <20140909040352.GC20518@dastard> (raw)
In-Reply-To: <1410092760-3451-2-git-send-email-bfoster@redhat.com>
On Sun, Sep 07, 2014 at 08:25:57AM -0400, Brian Foster wrote:
> The collapse range implementation uses a transaction per extent shift.
> The progress of the overall operation is tracked via the current extent
> index of the in-core extent list. This is racy because the ilock must be
> dropped and reacquired for each transaction according to locking and log
> reservation rules. Therefore, writeback to prior regions of the file is
> possible and can change the extent count. This changes the extent to
> which the current index refers and causes the collapse to fail mid
> operation. To avoid this problem, the entire file is currently written
> back before the collapse operation starts.
>
> To eliminate the need to flush the entire file, use the file offset
> (fsb) to track the progress of the overall extent shift operation rather
> than the extent index. Modify xfs_bmap_shift_extents() to
> unconditionally convert the start_fsb parameter to an extent index and
> return the file offset of the extent where the shift left off, if
> further extents exist. The bulk of ths function can remain based on
> extent index as ilock is held by the caller. xfs_collapse_file_space()
> now uses the fsb output as the starting point for the subsequent shift.
>
> Signed-off-by: Brian Foster <bfoster@redhat.com>
Looks good. There's a couple of small things I noticed, but
they aren't worth redoing the patches again to fix.
Reviewed-by: Dave Chinner <dchinner@redhat.com>
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2014-09-09 4:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-07 12:25 [PATCH 0/4] clean up collapse range and handle post-eof delalloc Brian Foster
2014-09-07 12:25 ` [PATCH 1/4] xfs: track collapse via file offset rather than extent index Brian Foster
2014-09-09 4:03 ` Dave Chinner [this message]
2014-09-07 12:25 ` [PATCH 2/4] xfs: refactor xfs_bmap_shift_extents() into multiple functions Brian Foster
2014-09-09 5:08 ` Dave Chinner
2014-09-09 15:04 ` Brian Foster
2014-09-07 12:25 ` [PATCH 3/4] xfs: writeback and inval. file range to be shifted by collapse Brian Foster
2014-09-09 5:13 ` Dave Chinner
2014-09-09 15:16 ` Brian Foster
2014-09-07 12:26 ` [PATCH 4/4] xfs: only writeback and truncate pages for the freed range Brian Foster
2014-09-09 5:14 ` Dave Chinner
-- strict thread matches above, loose matches on Subject: below --
2014-08-29 20:29 [RFC PATCH 0/4] clean up collapse range and handle post-eof delalloc Brian Foster
2014-08-29 20:29 ` [PATCH 1/4] xfs: track collapse via file offset rather than extent index Brian Foster
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