Re: [PATCH v3 02/13] common/rc: Fix fsx for ext4 with bigalloc

[Darrick J. Wong]

On Sat, Jul 12, 2025 at 07:42:44PM +0530, Ojaswin Mujoo wrote:
> Insert range and collapse range only works with bigalloc in case
> the range is cluster size aligned, which fsx doesnt take care. To
> work past this, disable insert range and collapse range on ext4, if
> bigalloc is enabled.
> 
> This is achieved by defining a new function _set_default_fsx_avoid
> called via run_fsx helper. This can be used to selectively disable
> fsx options based on the configuration.
> 
> Co-developed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
> Signed-off-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx>
> ---
>  common/rc | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/common/rc b/common/rc
> index 9a9d3cc8..218cf253 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -5113,10 +5113,37 @@ _require_hugepage_fsx()
>  		_notrun "fsx binary does not support MADV_COLLAPSE"
>  }
>  
> +_set_default_fsx_avoid() {
> +	local file=$1
> +
> +	case "$FSTYP" in
> +	"ext4")
> +		local dev=$(findmnt -n -o SOURCE --target $file)
> +
> +		# open code instead of _require_dumpe2fs cause we don't
> +		# want to _notrun if dumpe2fs is not available
> +		if [ -z "$DUMPE2FS_PROG" ]; then
> +			echo "_set_default_fsx_avoid: dumpe2fs not found, skipping bigalloc check." >> $seqres.full
> +			return
> +		fi

I hate to be the guy who says one thing and then another, but ...

If we extended _get_file_block_size to report the ext4 bigalloc cluster
size, would that be sufficient to keep testing collapse/insert range?

I guess the tricky part here is that bigalloc allows sub-cluster
mappings and we might not want to do all file IO testing in such big
units.

> +
> +		$DUMPE2FS_PROG -h $dev 2>&1 | grep -q bigalloc && {
> +			export FSX_AVOID+=" -I -C"

No need to export FSX_AVOID to subprocesses.

--D

> +		}
> +		;;
> +	# Add other filesystem types here as needed
> +	*)
> +		;;
> +	esac
> +}
> +
>  _run_fsx()
>  {
>  	echo "fsx $*"
>  	local args=`echo $@ | sed -e "s/ BSIZE / $bsize /g" -e "s/ PSIZE / $psize /g"`
> +
> +	_set_default_fsx_avoid $testfile
> +
>  	set -- $FSX_PROG $args $FSX_AVOID $TEST_DIR/junk
>  	echo "$@" >>$seqres.full
>  	rm -f $TEST_DIR/junk
> -- 
> 2.49.0
> 
>