Re: [PATCH 3/4] common/rc: fix detection of device-mapper/persistent memory incompatibility

[Chandan Babu R <chandanrlinux@gmail.com>]

On 03 Mar 2021 at 04:52, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
>
> In commit fc7b3903, we tried to make _require_dm_target smart enough to
> _notrun tests that require a device mapper target that isn't compatible
> with "DAX".  However, as of this writing, the incompatibility stems from
> device mapper's unwillingness to switch access modes when running atop
> DAX (persistent memory) devices, and has nothing to do with the
> filesystem mount options.
>
> Since filesystems supporting DAX don't universally require "dax" in the
> mount options to enable that functionality, switch the test to query
> sysfs to see if the scratch device supports DAX.

Looks good to me.

Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

>
> Fixes: fc7b3903 ("dax/dm: disable testing on devices that don't support dax")
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  common/rc |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
>
> diff --git a/common/rc b/common/rc
> index 7254130f..10e5f40b 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -1889,7 +1889,8 @@ _require_dm_target()
>  	_require_sane_bdev_flush $SCRATCH_DEV
>  	_require_command "$DMSETUP_PROG" dmsetup
>  
> -	_normalize_mount_options | egrep -q "dax(=always| |$)"
> +	_normalize_mount_options | egrep -q "dax(=always| |$)" || \
> +			test -e "/sys/block/$(_short_dev $SCRATCH_DEV)/dax"
>  	if [ $? -eq 0 ]; then
>  		case $target in
>  		stripe|linear|log-writes)


-- 
chandan