Re: [PATCH v3] generic/798: chain xfs_io commands into a single invocation

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2026/8/27 01:24, Avinesh Kumar 写道:
> From: Avinesh Kumar <avinesh.kumar@suse.com>
> 
> The write, cachestat, fsync, and cachestat calls were each run as
> separate xfs_io invocations, closing and reopening the file in
> between. Some filesystems flush dirty data back on close(), clearing
> the dirty bit before the first cachestat ever ran, causing test failure
> 
> - output mismatch (see /opt/xfstests/results//generic/798.out.bad)
>      --- tests/generic/798.out	2026-08-20 05:25:39.000000000 -0400
>      +++ /opt/xfstests/results//generic/798.out.bad	2026-08-21 12:30:39.831381108 -0400
>      @@ -1,16 +1,16 @@
>       QA output created by 798
>       === Test with 1 pages ===
>      -Cached: 1, Dirty: 1, Writeback: 0, Evicted: 0, Recently Evicted: 0
>      +Cached: 1, Dirty: 0, Writeback: 0, Evicted: 0, Recently Evicted: 0
>       Cached: 1, Dirty: 0, Writeback: 0, Evicted: 0, Recently Evicted: 0
>       === Test with 2 pages ===
>      -Cached: 2, Dirty: 2, Writeback: 0, Evicted: 0, Recently Evicted: 0
>      ...
> 
> Run the whole sequence on one open file descriptor instead by chaining
> all xfs_io commands in single invocation.
> 
> Suggested-by: "Darrick J. Wong" <djwong@kernel.org>
> Signed-off-by: Avinesh Kumar <avinesh.kumar@suse.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu

> ---
>   tests/generic/798 | 19 ++++++++++++++-----
>   1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/tests/generic/798 b/tests/generic/798
> index 0fe37646..5c81b429 100755
> --- a/tests/generic/798
> +++ b/tests/generic/798
> @@ -27,12 +27,21 @@ for num_page in 1 2 4 8 16; do
>   	echo "=== Test with $num_page pages ==="
>   
>   	rm -f $SCRATCH_MNT/foobar
> -	$XFS_IO_PROG -f -c "pwrite -b $pagesize 0 $size" $SCRATCH_MNT/foobar > /dev/null
> -	# Basic cached number reporting
> -	$XFS_IO_PROG -c "cachestat 0 $size" $SCRATCH_MNT/foobar
>   
> -	# Test dirty page number reporting after a fsync.
> -	$XFS_IO_PROG -c "fsync" -c "cachestat 0 $size" $SCRATCH_MNT/foobar
> +	# Basic cached number reporting and test dirty page number
> +	# reporting after a fsync.
> +	#
> +	# Do the whole write+cachestat+fsync+cachestat sequence in a
> +	# single xfs_io invocation. Some filesystems (e.g. NFS) flush
> +	# dirty data back to the server as part of their own close()-time
> +	# cache consistency, which would clear the dirty bits before the
> +	# second xfs_io process ever got to run cachestat.
> +	$XFS_IO_PROG -f \
> +		-c "pwrite -q -b $pagesize 0 $size" \
> +		-c "cachestat 0 $size" \
> +		-c "fsync" \
> +		-c "cachestat 0 $size" \
> +		$SCRATCH_MNT/foobar
>   done
>   
>   _scratch_unmount