Re: [PATCH] common/rc: Modify _require_batched_discard to improve test coverage

[Ojaswin Mujoo]

Greetings,

Please do let me know if there are any reviews or comments on this patch.

Thank you,
Ojaswin

On Fri, Apr 01, 2022 at 11:27:13AM +0530, Ojaswin Mujoo wrote:
> A recent ext4 patch discussed [1] that some devices (eg LVMs) can
> have a discard granularity as big as 42MB which makes it larger
> than the group size of ext4 FS with 1k BS. This causes the FITRIM
> IOCTL to fail on filesystems like ext4.
> 
> This case was not correctly handle by "_require_batched_discard" as
> it incorrectly interpreted the FITRIM failure as fs not supporting
> the IOCTL. This caused the tests like generic/260 to incorectly
> report "not run" instead of "failed" in case of large discard
> granularity.
> 
> Fix "_require_batched_discard" to use a more accurate method
> to determine if discard is supported.
> 
> [1] commit 173b6e383d2
>     ext4: avoid trim error on fs with small groups
> 
> Signed-off-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx>
> ---
>  common/rc | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/common/rc b/common/rc
> index e2d3d72a..97386342 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -3858,7 +3858,13 @@ _require_batched_discard()
>  		exit 1
>  	fi
>  	_require_fstrim
> -	$FSTRIM_PROG $1 > /dev/null 2>&1 || _notrun "FITRIM not supported on $1"
> +
> +	$FSTRIM_PROG $1 2>&1 | grep -q "not supported"
> +	RET=$?
> +	if [ "$RET" = "0" ]
> +	then
> +		_notrun "FITRIM not supported on $1"
> +	fi
>  }
>  
>  _require_dumpe2fs()
> -- 
> 2.27.0
>