Re: [PATCH 2/3] rc: check dax mode in _require_scratch_swapfile

Brian Foster
2021-04-28T18:04:19Z

On Tue, Apr 27, 2021 at 09:09:41PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
>
> It turns out that the mm refuses to swapon() files that don't have a
> a_ops->readpage function, because it wants to be able to read the swap
> header. S_DAX files don't have a readpage function (though oddly both
> ext4 and xfs link to a swapfile activation function in their aops) so
> they fail. The recent commit 725feeff changed this from a _notrun to
> _fail on xfs and ext4, so amend this not to fail on pmem test setups.
>
> Fixes: 725feeff ("common/rc: swapon should not fail for given FS in _require_scratch_swapfile()")
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

> common/rc | 4 ++++
> 1 file changed, 4 insertions(+)
>
>
> diff --git a/common/rc b/common/rc
> index 6752c92d..429cc24d 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -2490,6 +2490,10 @@ _require_scratch_swapfile()
> # Minimum size for mkswap is 10 pages
> _format_swapfile "$SCRATCH_MNT/swap" $(($(get_page_size) * 10))
>
> + # swapfiles cannot use cpu direct access mode (STATX_ATTR_DAX) for now
> + statx_attr="$($XFS_IO_PROG -c 'statx -r' $SCRATCH_MNT/swap 2>/dev/null | grep 'stat.attributes = ' | awk '{print $3}')"
> + test "$((statx_attr & 0x200000))" -gt 0 && _notrun "swapfiles not supported on DAX"
> +
> # ext* and xfs have supported all variants of swap files since their
> # introduction, so swapon should not fail.
> case "$FSTYP" in
>