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

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

On Wed, Apr 09, 2025 at 12:05:11AM +0800, Anand Jain wrote:
> 
> 
> On 8/4/25 01:22, Darrick J. Wong wrote:
> > 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?
> > 
> 
> Do you mean, instead of using _fail, just echo "Usage" and return 1?

Doh, I missed that it was _fail and not echo.  Please ignore my
comment.

> > > +
> > > +	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?
> > 
> 
> 
> Ah, I missed the `if`—updated it locally now.
> 
> @@ -25,7 +25,9 @@ _has_fs_sysfs_attr_policy()
>         fi
> 
>         local dname=$(_fs_sysfs_dname $dev)
> -       test -e /sys/fs/${FSTYP}/${dname}/${attr}
> +       if test -e /sys/fs/${FSTYP}/${dname}/${attr}; then
> +               return 1
> +       fi

<nod>

>         cat /sys/fs/${FSTYP}/${dname}/${attr} | grep -q ${policy}
>  }
> 
> 
> > > +
> > > +	cat /sys/fs/${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 ... ?
> 
> Yeah, I commented it out since it's just an example.
> I think I need to rephrase the comment.

Ok.

--D

> Thanks, Anand
> 
> > 
> > --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
> > > 
> > > 
> 
>