Re: [PATCH v3 1/2] common/dmlogwrites: add _require_log_writes_sized helper

[Zorro Lang <zlang@kernel.org>]

On Fri, May 08, 2026 at 08:17:00PM +0530, Disha Goel wrote:
> Add a new helper function _require_log_writes_sized() to check if the
> LOGWRITES_DEV meets a minimum size requirement.
> 
> This is useful for tests that use dm-log-writes with additional space
> requirements, such as creating LVM snapshots during log replay or tests
> that generate large amounts of logged I/O operations.
> 
> The function takes a size parameter in KB, calls _require_log_writes()
> internally, and skips the test if LOGWRITES_DEV is smaller than the
> required size.
> 
> Suggested-by: Darrick J. Wong <djwong@kernel.org>
> Suggested-by: Anand Jain <anajain.sg@gmail.com>
> Signed-off-by: Disha Goel <disgoel@linux.ibm.com>
> ---
> v2 -> v3:
> - Fixed variable declaration order - declare all local variables at the
>   beginning of the function
> - Use $size instead of $1 for clarity in the comparison
> 
>  common/dmlogwrites | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/common/dmlogwrites b/common/dmlogwrites
> index a27e1966..b457ef7f 100644
> --- a/common/dmlogwrites
> +++ b/common/dmlogwrites
> @@ -14,6 +14,22 @@ _require_log_writes()
>  	_require_test_program "log-writes/replay-log"
>  }
>  
> +# Require a log writes device of a minimum size
> +# $1: minimum size in KB
> +_require_log_writes_sized()

Makes sense to me. Although I think we can support 'size checking' in original
_require_log_writes helper too, but I don't have objection on this change. Thanks

Reviewed-by: Zorro Lang <zlang@kernel.org>

> +{
> +	local size=$1
> +	local devsize
> +
> +	[ $# -eq 1 ] || _fail "_require_log_writes_sized: expected size param"
> +
> +	_require_log_writes
> +
> +	devsize=$(_get_device_size $LOGWRITES_DEV)
> +	[ $devsize -lt $size ] && \
> +		_notrun "LOGWRITES_DEV too small, ${devsize}KB < ${size}KB"
> +}
> +
>  # Starting from v4.15-rc1, DAX support was added to dm-log-writes, but note
>  # that it doesn't track the data that we write via the mmap(), so we can't do
>  # any data integrity checking. We can only verify that the metadata writes for
> -- 
> 2.45.1
>