Re: [PATCH V2 1/3] dax/dm: disable testing on devices that don't support dax

[Zorro Lang <zlang@redhat.com>]

On Thu, Feb 20, 2020 at 03:06:30PM -0500, Jeff Moyer wrote:
> Move the check for dax from the individual target scripts into
> _require_dm_target.  This fixes up a couple of missed tests that are
> failing due to the lack of dax support (such as tests requiring
> dm-snapshot).
> 
> Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
> ---
>  common/dmdelay  |  5 -----
>  common/dmerror  |  5 -----
>  common/dmflakey |  5 -----
>  common/dmthin   |  5 -----
>  common/rc       | 11 +++++++++++
>  5 files changed, 11 insertions(+), 20 deletions(-)
> 
> diff --git a/common/dmdelay b/common/dmdelay
> index f1e725b9..66cac1a7 100644
> --- a/common/dmdelay
> +++ b/common/dmdelay
> @@ -7,11 +7,6 @@
>  DELAY_NONE=0
>  DELAY_READ=1
>  
> -echo $MOUNT_OPTIONS | grep -q dax
> -if [ $? -eq 0 ]; then
> -	_notrun "Cannot run tests with DAX on dmdelay devices"
> -fi
> -
>  _init_delay()
>  {
>  	local BLK_DEV_SIZE=`blockdev --getsz $SCRATCH_DEV`
> diff --git a/common/dmerror b/common/dmerror
> index 426f1e96..7d12e0a1 100644
> --- a/common/dmerror
> +++ b/common/dmerror
> @@ -4,11 +4,6 @@
>  #
>  # common functions for setting up and tearing down a dmerror device
>  
> -echo $MOUNT_OPTIONS | grep -q dax
> -if [ $? -eq 0 ]; then
> -	_notrun "Cannot run tests with DAX on dmerror devices"
> -fi
> -
>  _dmerror_setup()
>  {
>  	local dm_backing_dev=$SCRATCH_DEV
> diff --git a/common/dmflakey b/common/dmflakey
> index 2af3924d..b4e11ae9 100644
> --- a/common/dmflakey
> +++ b/common/dmflakey
> @@ -8,11 +8,6 @@ FLAKEY_ALLOW_WRITES=0
>  FLAKEY_DROP_WRITES=1
>  FLAKEY_ERROR_WRITES=2
>  
> -echo $MOUNT_OPTIONS | grep -q dax
> -if [ $? -eq 0 ]; then
> -	_notrun "Cannot run tests with DAX on dmflakey devices"
> -fi
> -
>  _init_flakey()
>  {
>  	local BLK_DEV_SIZE=`blockdev --getsz $SCRATCH_DEV`
> diff --git a/common/dmthin b/common/dmthin
> index 7946e9a7..61dd6f89 100644
> --- a/common/dmthin
> +++ b/common/dmthin
> @@ -21,11 +21,6 @@ DMTHIN_POOL_DEV="/dev/mapper/$DMTHIN_POOL_NAME"
>  DMTHIN_VOL_NAME="thin-vol"
>  DMTHIN_VOL_DEV="/dev/mapper/$DMTHIN_VOL_NAME"
>  
> -echo $MOUNT_OPTIONS | grep -q dax
> -if [ $? -eq 0 ]; then
> -	_notrun "Cannot run tests with DAX on dmthin devices"
> -fi
> -
>  _dmthin_cleanup()
>  {
>  	$UMOUNT_PROG $SCRATCH_MNT > /dev/null 2>&1
> diff --git a/common/rc b/common/rc
> index eeac1355..65cde32b 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -1874,6 +1874,17 @@ _require_dm_target()
>  	_require_sane_bdev_flush $SCRATCH_DEV
>  	_require_command "$DMSETUP_PROG" dmsetup
>  
> +	echo $MOUNT_OPTIONS | grep -q dax
> +	if [ $? -eq 0 ]; then
> +		case $target in
> +		stripe|linear|log-writes)

I've checked all cases which import ./common/dm.* (without dmapi), they all
has _require_dm_target. So this patch is good to me.

And by checking current linux source code:

  0 dm-linear.c      226 .direct_access = linear_dax_direct_access,
  1 dm-log-writes.c 1016 .direct_access = log_writes_dax_direct_access,
  2 dm-stripe.c      486 .direct_access = stripe_dax_direct_access,
  3 dm-target.c      159 .direct_access = io_err_dax_direct_access,

Only linear, stripe and log-writes support direct_access.

Thanks,
Zorro

> +			;;
> +		*)
> +			_notrun "Cannot run tests with DAX on $target devices."
> +			;;
> +		esac
> +	fi
> +
>  	modprobe dm-$target >/dev/null 2>&1
>  
>  	$DMSETUP_PROG targets 2>&1 | grep -q ^$target
> -- 
> 2.19.1
>