Re: [PATCH 1/2] xfstests: support dm-delay to introduce I/O delays

[Eryu Guan <eguan@redhat.com>]

On Thu, Jun 30, 2016 at 08:49:33AM -0400, Brian Foster wrote:
> Add some infrastructure in common/dmdelay to support use of the dm-delay
> device-mapper module within tests. This is effectively copied from the
> existing infrastructure in common/dmflakey. This provides the ability to
> delay I/O. It only supports delaying read I/O as that is all that is
> required at this point in time.
> 
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> ---
>  common/dmdelay | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 89 insertions(+)
>  create mode 100644 common/dmdelay
> 
> diff --git a/common/dmdelay b/common/dmdelay
> new file mode 100644
> index 0000000..c53e2dd
> --- /dev/null
> +++ b/common/dmdelay
> @@ -0,0 +1,89 @@
> +##/bin/bash
> +#
> +# Copyright (c) 2016 Red Hat, Inc.  All Rights Reserved.
> +#
> +# This program is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU General Public License as
> +# published by the Free Software Foundation.
> +#
> +# This program is distributed in the hope that it would be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write the Free Software Foundation,
> +# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> +#
> +#
> +# common functions for setting up and tearing down a dmdelay device
> +
> +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`
> +	DELAY_DEV=/dev/mapper/delay-test
> +	DELAY_TABLE="0 $BLK_DEV_SIZE delay $SCRATCH_DEV 0 0"
> +	DELAY_TABLE_RDELAY="0 $BLK_DEV_SIZE delay $SCRATCH_DEV 0 10000 $SCRATCH_DEV 0 0"
> +	$DMSETUP_PROG create delay-test --table "$DELAY_TABLE" || \
> +		_fatal "failed to create delay device"
> +	$DMSETUP_PROG mknodes > /dev/null 2>&1
> +}
> +
> +_mount_delay()
> +{
> +	_scratch_options mount
> +	mount -t $FSTYP $SCRATCH_OPTIONS $MOUNT_OPTIONS $DELAY_DEV $SCRATCH_MNT

I replaced mount with $MOUNT_PROG :)

> +}
> +
> +_unmount_delay()
> +{
> +	$UMOUNT_PROG $SCRATCH_MNT
> +}
> +
> +_cleanup_delay()
> +{
> +	# If dmsetup load fails then we need to make sure to do resume here
> +	# otherwise the umount will hang
> +	$DMSETUP_PROG resume delay-test > /dev/null 2>&1
> +	$UMOUNT_PROG $SCRATCH_MNT > /dev/null 2>&1
> +	# wait for device to be fully settled so that 'dmsetup remove' doesn't
> +	# fail due to EBUSY
> +	$UDEV_SETTLE_PROG >/dev/null 2>&1
> +	$DMSETUP_PROG remove delay-test > /dev/null 2>&1
> +	$DMSETUP_PROG mknodes > /dev/null 2>&1
> +}
> +
> +# _load_delay_table <table> [lockfs]
> +#
> +# This defaults to --nolockfs, which doesn't freeze_fs() before loading the new
> +# table, so it simulates power failure.

Seems this comment is for dmflakey and needs update. Can you please
confirm? I can fix it at commit time if needs update, no v2 is needed.

Thanks,
Eryu

> +_load_delay_table()
> +{
> +	table="$DELAY_TABLE"
> +	[ $1 -eq $DELAY_READ ] && table="$DELAY_TABLE_RDELAY"
> +
> +	suspend_opt="--nolockfs"
> +	[ $# -gt 1 ] && [ $2 -eq 1 ] && suspend_opt=""
> +
> +	# run a suspend/resume cycle to avoid excessive resume delays once a
> +	# delay is introduced below
> +	$DMSETUP_PROG suspend $suspend_opt delay-test
> +	$DMSETUP_PROG resume $suspend_opt delay-test
> +
> +	$DMSETUP_PROG suspend $suspend_opt delay-test
> +	[ $? -ne 0 ] && _fatal "failed to suspend delay-test"
> +
> +	$DMSETUP_PROG load delay-test --table "$table"
> +	[ $? -ne 0 ] && _fatal "failed to load table into delay-test"
> +
> +	$DMSETUP_PROG resume delay-test
> +	[ $? -ne 0 ] && _fatal  "failed to resume delay-test"
> +}
> -- 
> 2.5.5
> 
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