linux-kernel - Re: [PATCH 04/16] block: allow blk-zoned devices to have non-power-of-2 zone size

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Message-ID: <c76334a9-3d10-ed3c-f4d1-d856f67928e6@suse.de>
Date:   Wed, 4 May 2022 09:59:15 -0700
From:   Hannes Reinecke <hare@...e.de>
To:     undisclosed-recipients:;
Subject: Re: [PATCH 04/16] block: allow blk-zoned devices to have
 non-power-of-2 zone size

On 4/27/22 09:02, Pankaj Raghav wrote:
> Convert the calculations on zone size to be generic instead of relying on
> power_of_2 based logic in the block layer using the helpers wherever
> possible.
> 
> The only hot path affected by this change for power_of_2 zoned devices
> is in blk_check_zone_append() but the effects should be negligible as the
> helper blk_queue_zone_aligned() optimizes the calculation for those
> devices. Note that the append path cannot be accessed by direct raw access
> to the block device but only through a filesystem abstraction.
> 
> Finally, remove the check for power_of_2 zone size requirement in
> blk-zoned.c
> 
> Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> ---
>   block/blk-core.c  |  3 +--
>   block/blk-zoned.c | 12 ++++++------
>   2 files changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 937bb6b86331..850caf311064 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -634,8 +634,7 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q,
>   		return BLK_STS_NOTSUPP;
>   
>   	/* The bio sector must point to the start of a sequential zone */
> -	if (pos & (blk_queue_zone_sectors(q) - 1) ||
> -	    !blk_queue_zone_is_seq(q, pos))
> +	if (!blk_queue_zone_aligned(q, pos) || !blk_queue_zone_is_seq(q, pos))
>   		return BLK_STS_IOERR;
>   
>   	/*
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 1dff4a8bd51d..f7c7c3bd148d 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -288,10 +288,10 @@ int blkdev_zone_mgmt(struct block_device *bdev, enum req_opf op,
>   		return -EINVAL;
>   
>   	/* Check alignment (handle eventual smaller last zone) */
> -	if (sector & (zone_sectors - 1))
> +	if (!blk_queue_zone_aligned(q, sector))
>   		return -EINVAL;
>   
> -	if ((nr_sectors & (zone_sectors - 1)) && end_sector != capacity)
> +	if (!blk_queue_zone_aligned(q, nr_sectors) && end_sector != capacity)
>   		return -EINVAL;
>   
>   	/*
> @@ -489,14 +489,14 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
>   	 * smaller last zone.
>   	 */
>   	if (zone->start == 0) {
> -		if (zone->len == 0 || !is_power_of_2(zone->len)) {
> -			pr_warn("%s: Invalid zoned device with non power of two zone size (%llu)\n",
> -				disk->disk_name, zone->len);
> +		if (zone->len == 0) {
> +			pr_warn("%s: Invalid zoned device size",
> +				disk->disk_name);
>   			return -ENODEV;
>   		}
>   
>   		args->zone_sectors = zone->len;
> -		args->nr_zones = (capacity + zone->len - 1) >> ilog2(zone->len);
> +		args->nr_zones = div64_u64(capacity + zone->len - 1, zone->len);

This is a different calculation than the one you're using in the first 
patch. Can you please add a helper such that both are using the same 
calculation?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@...e.de                              +49 911 74053 688
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