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

Darrick J. Wong
2021-04-28T04:09:43Z

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>
---
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