[PATCH] fstests: _require_dm_target should not always skip DAX capable devices

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

Recent changes have turned off all dm-error, dm-thin and dm-flakey
tests on pmem devices even when we are not explicitly testing DAX.
This is a regression resulting in a large number of log recovery
tests no longer running on my pmem-based test VMs. I added the "-o
dax=never" mount options to these test configs, only to find it
still would not run the dm tests even though the filesystem will
never use DAX.

Fix this so that the dm target DAX test explicitly ignores the
the block device DAX capability when the filesystem is mounted with
dax=never and hence we can use all the dm targets when the tests are
being run with FSDAX disabled.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 common/rc | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/common/rc b/common/rc
index 7f693d39..0cbe8a7d 100644
--- a/common/rc
+++ b/common/rc
@@ -1965,12 +1965,19 @@ _require_sane_bdev_flush()
 }
 
 # Decide if the scratch filesystem is likely to be mounted in fsdax mode.
-# If there's a dax clause in the mount options we assume the test runner
-# wants us to test DAX; or if the scratch device itself advertises dax mode
-# in sysfs.
-__detect_scratch_fsdax()
+# It goes 3 ways based on mount options::
+#	1. "dax" or "dax=always" means always test using DAX
+#	2. "dax=never" means we'll never use DAX
+#	3. "dax=inode" or nothing means "use scratch dev capability" to
+#	    determine whether DAX is going to be used.
+#
+# Returns 0 if DAX will be used, 1 if DAX is not going to be used.
+__scratch_uses_fsdax()
 {
-	_normalize_mount_options | egrep -q "dax(=always| |$)" && return 0
+	local ops=$(_normalize_mount_options)
+
+	echo $ops | egrep -q "dax(=always| |$)" && return 0
+	echo $ops | grep -q "dax=never" && return 1
 
 	local sysfs="/sys/block/$(_short_dev $SCRATCH_DEV)"
 	test -e "${sysfs}/dax" && return 0
@@ -1982,6 +1989,8 @@ __detect_scratch_fsdax()
 _require_dm_target()
 {
 	local target=$1
+	local fsdax
+	local bdevdax
 
 	# require SCRATCH_DEV to be a valid block device with sane BLKFLSBUF
 	# behaviour
@@ -1989,7 +1998,7 @@ _require_dm_target()
 	_require_sane_bdev_flush $SCRATCH_DEV
 	_require_command "$DMSETUP_PROG" dmsetup
 
-	if __detect_scratch_fsdax; then
+	if __scratch_uses_fsdax; then
 		case $target in
 		stripe|linear|log-writes)
 			;;
-- 
2.33.0