[Devel] [PATCH RH9 v3 4/8] dm/dm-qcow2: add calc_front_qio_bytes() helper

[Alexander Atanasov]

On 5.09.23 11:59, Andrey Zhadchenko wrote:
> Move code that calculates qio front bytes type and amount into a new
> helper. Increase code clarity.
> This will be used later for llseek_hole()
> 
> Feature: dm: implement SEEK_HOLE for dm-qcow2 and dm-ploop
> https://jira.vzint.dev/browse/PSBM-145746
> Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
> 
> ---
> v3: reworked the code to make it more clear
> 
>   drivers/md/dm-qcow2-map.c | 50 +++++++++++++++++++++++++++++----------
>   1 file changed, 37 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c
> index a779889c6970..7d5e33724ccb 100644
> --- a/drivers/md/dm-qcow2-map.c
> +++ b/drivers/md/dm-qcow2-map.c
> @@ -3341,27 +3341,51 @@ static int handle_metadata(struct qcow2 *qcow2, struct qio **qio,
>   	return ret;
>   }
>   
> +struct calc_front_bytes_ret {
> +	bool unmapped;
> +	bool zeroes;
> +	bool try_lower;
> +};
> +
> +static inline u32 calc_front_qio_bytes(struct qcow2 *qcow2, struct qio *qio,
> +				       struct qcow2_map *map,
> +				       struct calc_front_bytes_ret *arg)
> +{
> +	u32 size;
> +
> +	arg->unmapped = false;
> +	arg->zeroes = false;
> +	arg->try_lower = false;
> +
> +	size = qio_all_zeroes_size(qcow2, qio, map);
> +	if (size) {
> +		arg->zeroes = true;
> +		return size;
> +	}
> +
> +	size = qio_unmapped_size(qcow2, qio, map);
> +	if (size) {
> +		arg->unmapped = true;
> +		arg->try_lower = maybe_mapped_in_lower_delta(qcow2, qio);
> +		return size;
> +	}
> +
> +	size = qio_mapped_not_zeroes_size(qcow2, qio, map);
> +	return size;
> +}
> +
>   static void process_read_qio(struct qcow2 *qcow2, struct qio *qio,
>   			     struct qcow2_map *map)
>   {
> -	bool unmapped, zeroes, try_lower;
> +	struct calc_front_bytes_ret arg;
>   	struct qio *split;
>   	u32 size;
>   
>   	do {
> -		unmapped = try_lower = false;
>   		split = NULL;
> +		size = calc_front_qio_bytes(qcow2, qio, map, &arg);
>   
> -		zeroes = (size = qio_all_zeroes_size(qcow2, qio, map));
> -		if (!size)
> -			unmapped = (size = qio_unmapped_size(qcow2, qio, map));
> -		if (!size)
> -			size = qio_mapped_not_zeroes_size(qcow2, qio, map);
> -
> -		if (unmapped)
> -			try_lower = maybe_mapped_in_lower_delta(qcow2, qio);
> -
> -		if (zeroes || (unmapped && !try_lower)) {
> +		if (arg.zeroes || (arg.unmapped && !arg.try_lower)) {
>   			/* All zeroes or clu is not allocated */
>   			perform_zero_read(qio, size);
>   			if (size == qio->bi_iter.bi_size) {
> @@ -3379,7 +3403,7 @@ static void process_read_qio(struct qcow2 *qcow2, struct qio *qio,
>   			swap(qio, split);
>   		}
>   
> -		if (unmapped && try_lower) {
> +		if (arg.unmapped && arg.try_lower) {
>   			/* Try to read from lower delta */
>   			shorten_and_zero_qio_tail(qcow2->lower, qio);
>   			qio->qcow2 = qcow2->lower;


LGTM

-- 
Regards,
Alexander Atanasov