Re: [PATCH v2 4/3] xfs: attach dquots to inode before reading data/cow fork mappings

[Dave Chinner <david@fromorbit.com>]

On Tue, Nov 29, 2022 at 01:05:24PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> I've been running near-continuous integration testing of online fsck,
> and I've noticed that once a day, one of the ARM VMs will fail the test
> with out of order records in the data fork.
> 
> xfs/804 races fsstress with online scrub (aka scan but do not change
> anything), so I think this might be a bug in the core xfs code.  This
> also only seems to trigger if one runs the test for more than ~6 minutes
> via TIME_FACTOR=13 or something.
> https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfstests-dev.git/tree/tests/xfs/804?h=djwong-wtf
> 
> I added a debugging patch to the kernel to check the data fork extents
> after taking the ILOCK, before dropping ILOCK, and before and after each
> bmapping operation.  So far I've narrowed it down to the delalloc code
> inserting a record in the wrong place in the iext tree:
.....
> 
> So.  Fix this by moving the dqattach_locked call up before we take the
> ILOCK, like all the other callers in that file.
> 
> Fixes: a526c85c2236 ("xfs: move xfs_file_iomap_begin_delay around") # goes further back than this
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> Reviewed-by: Dave Chinner <dchinner@redhat.com>
> ---
> v2: just do a regular dqattach, and tweak the commit message to make it
> clearer if it's dave or me talking

All looks good, thanks for doing the updates :)

-Dave.
-- 
Dave Chinner
david@fromorbit.com