Re: [PATCH] xfs/141: use new errortag knob for crc error injection

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Jun 28, 2017 at 07:44:50AM -0400, Brian Foster wrote:
> Update the test to use the newly available sysfs errortag injection
> knobs. The errortag knob has replaced the previous custom knob in
> the kernel. Create a local helper to support the old knob for
> backwards compatibility.
> 
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> ---
> 
> This updates xfs/141 to use the new error injection tag sysfs knob that
> has replaced log_badcrc_factor in the latest XFS for-next tree.

Hmmm... for xfstests, I was thinking of rewriting the common/inject helpers:

# Requires that xfs_io inject command knows about this error type
_require_xfs_io_error_injection()
{
	type="$1"

	shortdev=$(_short_dev $TEST_DEV)
	tagfile=/sys/fs/xfs/$shortdev/errortag/$type
	test -w $tagfile && return

	_require_error_injection

	if [ "$type" = "log_bad_crc" ]; then
		tagfile=/sys/fs/xfs/$shortdev/log/log_badcrc_factor
		test -w $tagfile && return
		_notrun "Cannot find log_badcrc_factor"
	fi

	# NOTE: We can't actually test error injection here because xfs
	# hasn't always range checked the argument to xfs_errortag_add.
	# We also don't want to trip an error before we're ready to deal
	# with it.

	$XFS_IO_PROG -x -c 'inject' $TEST_DIR | grep -q "$type" || \
		_notrun "XFS error injection $type unknown."
}

# Inject an error into the scratch fs
_scratch_inject_error()
{
	type="$1"
	value="$2"

	shortdev=$(_short_dev $SCRATCH_DEV)
	tagfile=/sys/fs/xfs/$shortdev/errortag/$type
	if [ -w $tagfile ]; then
		echo "$value" > $tagfile
		return
	fi

	if [ "$type" = "log_bad_crc" ]; then
		tagfile=/sys/fs/xfs/$shortdev/log/log_badcrc_factor
		if [ -w $tagfile ]; then
			echo "$value" > $tagfile
			return
		fi
		_notrun "cannot inject error $type value $value"
	elif [ -z "$value" ] || [ "$value" = "default" ]; then
		$XFS_IO_PROG -x -c "inject $type" $SCRATCH_MNT
	else
		_notrun "cannot inject error $type value $value"
	fi
}

...that way we can just change xfs/141 to do:

_require_xfs_io_error_injection "log_bad_crc"
...
for i in $(seq 1 5); do
 	# Enable error injection. Use a random bad crc factor up to 100
 	# (increase this value to run fsstress longer).
 	factor=$((RANDOM % 100 + 1))
	...
	_scratch_inject_error "log_bad_crc" "$factor"
	...
done

Therefore we can move all the other error injection knob tests (looking
at you, drop_writes) to a standard helper function that will cover all
the errortag knobs we're moving to sysfs.  Unfortunately we pay for that
uniformity by uglifying the helper functions to handle the old knobs,
but oh well.

I do wonder about the old xfs_io command, though -- while it's tempting
to rewrite it to do all the parsing required to get to sysfs, I'm not so
enthused about doing in C what can be done much more easily in bash.

--D

> 
> Brian
> 
>  tests/xfs/141 | 22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/tests/xfs/141 b/tests/xfs/141
> index 56ff14e..ea4f558 100755
> --- a/tests/xfs/141
> +++ b/tests/xfs/141
> @@ -43,6 +43,21 @@ _cleanup()
>  	wait > /dev/null 2>&1
>  }
>  
> +# require either the current error tag or the old custom log record crc error
> +# injection knob
> +_setup_bad_crc()
> +{
> +	if [ -e /sys/fs/xfs/$1/errortag/log_bad_crc ]; then
> +		badcrc_attr=/sys/fs/xfs/$1/errortag/log_bad_crc
> +		return
> +	fi
> +	if [ -e /sys/fs/xfs/$1/log/log_badcrc_factor ]; then
> +		badcrc_attr=/sys/fs/xfs/$1/log/log_badcrc_factor
> +		return
> +	fi
> +	_notrun "bad crc sysfs attribute not supported"
> +}
> +
>  rm -f $seqres.full
>  
>  # get standard environment, filters and checks
> @@ -53,7 +68,6 @@ rm -f $seqres.full
>  # Modify as appropriate.
>  _supported_fs xfs
>  _supported_os Linux
> -_require_xfs_sysfs $(_short_dev $TEST_DEV)/log/log_badcrc_factor
>  _require_scratch
>  _require_command "$KILLALL_PROG" killall
>  
> @@ -62,14 +76,14 @@ echo "Silence is golden."
>  _scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed"
>  _scratch_mount
>  
> -sdev=$(_short_dev $SCRATCH_DEV)
> +_setup_bad_crc $(_short_dev $SCRATCH_DEV)
>  
>  for i in $(seq 1 5); do
>  	# Enable error injection. Use a random bad crc factor up to 100
>  	# (increase this value to run fsstress longer).
>  	factor=$((RANDOM % 100 + 1))
> -	echo iteration $i log_badcrc_factor: $factor >> $seqres.full 2>&1
> -	echo $factor > /sys/fs/xfs/$sdev/log/log_badcrc_factor
> +	echo iteration $i bad crc factor: $factor >> $seqres.full 2>&1
> +	echo $factor > $badcrc_attr
>  
>  	# Run fsstress until the filesystem shuts down. It will shut down
>  	# automatically when error injection triggers.
> -- 
> 2.9.4
> 
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