Re: [PATCH v5 4/6] fstests: common/sysfs: add new file sysfs and helpers

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Apr 07, 2025 at 11:48:18AM +0800, Anand Jain wrote:
> Introduce `verify_sysfs_syntax()` and `_require_fs_sysfs_attr_policy()`
> to verify whether a sysfs attribute rejects invalid input arguments
> during writes.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  common/sysfs | 141 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 141 insertions(+)
>  create mode 100644 common/sysfs
> 
> diff --git a/common/sysfs b/common/sysfs
> new file mode 100644
> index 000000000000..9f2d77c6b1f5
> --- /dev/null
> +++ b/common/sysfs
> @@ -0,0 +1,141 @@
> +##/bin/bash
> +# SPDX-License-Identifier: GPL-2.0+
> +# Copyright (c) 2025 Oracle.  All Rights Reserved.
> +#
> +# Common/sysfs file for the sysfs related helper functions.
> +
> +# Test for the existence of a policy at /sys/fs/$FSTYP/$DEV/$ATTR
> +#
> +# All arguments are necessary, and in this order:
> +#  - dev: device name, e.g. $SCRATCH_DEV
> +#  - attr: path name under /sys/fs/$FSTYP/$dev
> +#  - policy: policy within /sys/fs/$FSTYP/$dev
> +#
> +# Usage example:
> +#   _has_fs_sysfs_attr_policy /dev/mapper/scratch-dev read_policy round-robin
> +_has_fs_sysfs_attr_policy()
> +{
> +	local dev=$1
> +	local attr=$2
> +	local policy=$3
> +
> +	if [ ! -b "$dev" -o -z "$attr" -o -z "$policy" ]; then
> +		_fail \
> +	     "Usage: _has_fs_sysfs_attr_policy <mounted_device> <attr> <policy>"
> +	fi

Shouldn't this return 1 if the parameters are not fully specified?

> +
> +	local dname=$(_fs_sysfs_dname $dev)
> +	test -e /sys/fs/${FSTYP}/${dname}/${attr}

What is the point of testing path existence here if the function doesn't
actually change its behavior?

> +
> +	cat /sys/fs/${FSTYP}/${dname}/${attr} | grep -q ${policy}
> +}
> +
> +# Require the existence of a sysfs entry at /sys/fs/$FSTYP/$DEV/$ATTR
> +# and value in it contains $policy
> +# All arguments are necessary, and in this order:
> +#  - dev: device name, e.g. $SCRATCH_DEV
> +#  - attr: path name under /sys/fs/$FSTYP/$dev
> +#  - policy: mentioned in /sys/fs/$FSTYP/$dev/$attr
> +#
> +# Usage example:
> +#   _require_fs_sysfs_attr_policy /dev/mapper/scratch-dev read_policy round-robin
> +_require_fs_sysfs_attr_policy()
> +{
> +	_has_fs_sysfs_attr_policy "$@" && return
> +
> +	local dev=$1
> +	local attr=$2
> +	local policy=$3
> +	local dname=$(_fs_sysfs_dname $dev)
> +
> +	_notrun "This test requires /sys/fs/${FSTYP}/${dname}/${attr} ${policy}"
> +}
> +
> +_set_sysfs_policy()
> +{
> +	local dev=$1
> +	local attr=$2
> +	shift
> +	shift
> +	local policy=$@
> +
> +	_set_fs_sysfs_attr $dev $attr ${policy}
> +
> +	case "$FSTYP" in
> +	btrfs)
> +		_get_fs_sysfs_attr $dev $attr | grep -q "[${policy}]"
> +		if [[ $? != 0 ]]; then
> +			echo "Setting sysfs $attr $policy failed"
> +		fi
> +		;;
> +	*)
> +		_fail \
> +"sysfs syntax verification for '${attr}' '${policy}' for '${FSTYP}' is not implemented"
> +		;;
> +	esac
> +}
> +
> +_set_sysfs_policy_must_fail()
> +{
> +	local dev=$1
> +	local attr=$2
> +	shift
> +	shift
> +	local policy=$@
> +
> +	_set_fs_sysfs_attr $dev $attr ${policy} | _filter_sysfs_error \
> +							   | tee -a $seqres.full
> +}
> +
> +# Verify sysfs attribute rejects invalid input.
> +# Usage syntax:
> +#   _verify_sysfs_syntax <$dev> <$attr> <$policy> [$value]
> +# Examples:
> +#   _verify_sysfs_syntax $TEST_DEV read_policy pid
> +#   _verify_sysfs_syntax $TEST_DEV read_policy round-robin 4k
> +# Note:
> +#  Process must call . ./common/filter
> +_verify_sysfs_syntax()
> +{
> +	local dev=$1
> +	local attr=$2
> +	local policy=$3
> +	local value=$4
> +
> +	# Do this in the test case so that we know its prerequisites.
> +	# '_require_fs_sysfs_attr_policy $TEST_DEV $attr $policy'

But it's commented out ... ?

--D

> +
> +	# Test policy specified wrongly. Must fail.
> +	_set_sysfs_policy_must_fail $dev $attr "'$policy $policy'"
> +	_set_sysfs_policy_must_fail $dev $attr "'$policy t'"
> +	_set_sysfs_policy_must_fail $dev $attr "' '"
> +	_set_sysfs_policy_must_fail $dev $attr "'${policy} n'"
> +	_set_sysfs_policy_must_fail $dev $attr "'n ${policy}'"
> +	_set_sysfs_policy_must_fail $dev $attr "' ${policy}'"
> +	_set_sysfs_policy_must_fail $dev $attr "' ${policy} '"
> +	_set_sysfs_policy_must_fail $dev $attr "'${policy} '"
> +	_set_sysfs_policy_must_fail $dev $attr _${policy}
> +	_set_sysfs_policy_must_fail $dev $attr ${policy}_
> +	_set_sysfs_policy_must_fail $dev $attr _${policy}_
> +	_set_sysfs_policy_must_fail $dev $attr ${policy}:
> +	# Test policy longer than 32 chars fails stable.
> +	_set_sysfs_policy_must_fail $dev $attr 'jfdkkkkjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjffjfjfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff'
> +
> +	# Test policy specified correctly. Must pass.
> +	_set_sysfs_policy $dev $attr $policy
> +
> +	# If the policy has no value return
> +	if [[ -z $value ]]; then
> +		return
> +	fi
> +
> +	# Test value specified wrongly. Must fail.
> +	_set_sysfs_policy_must_fail $dev $attr "'$policy: $value'"
> +	_set_sysfs_policy_must_fail $dev $attr "'$policy:$value '"
> +	_set_sysfs_policy_must_fail $dev $attr "'$policy:$value typo'"
> +	_set_sysfs_policy_must_fail $dev $attr "'$policy:${value}typo'"
> +	_set_sysfs_policy_must_fail $dev $attr "'$policy :$value'"
> +
> +	# Test policy and value all specified correctly. Must pass.
> +	_set_sysfs_policy $dev $attr $policy:$value
> +}
> -- 
> 2.47.0
> 
>