linux-kernel - Re: [PATCH v8 02/11] block: allow blk-zoned devices to have non-power-of-2 zone size

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Date:   Wed, 27 Jul 2022 16:16:30 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Pankaj Raghav <p.raghav@...sung.com>,
        damien.lemoal@...nsource.wdc.com, hch@....de, axboe@...nel.dk,
        snitzer@...nel.org, Johannes.Thumshirn@....com
Cc:     matias.bjorling@....com, gost.dev@...sung.com,
        linux-kernel@...r.kernel.org, hare@...e.de,
        linux-block@...r.kernel.org, pankydev8@...il.com,
        jaegeuk@...nel.org, dm-devel@...hat.com,
        linux-nvme@...ts.infradead.org,
        Luis Chamberlain <mcgrof@...nel.org>
Subject: Re: [PATCH v8 02/11] block: allow blk-zoned devices to have
 non-power-of-2 zone size

On 7/27/22 09:22, Pankaj Raghav wrote:
> Checking if a given sector is aligned to a zone is a common
> operation that is performed for zoned devices. Add
> bdev_is_zone_start helper to check for this instead of opencoding it
> everywhere.

I can't find the bdev_is_zone_start() function in this patch?

> To make this work bdev_get_queue(), bdev_zone_sectors() and
> bdev_is_zoned() are moved earlier without modifications.

Can that change perhaps be isolated into a separate patch?

> diff --git a/block/blk-core.c b/block/blk-core.c
> index 3d286a256d3d..1f7e9a90e198 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -570,7 +570,7 @@ 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 (bio->bi_iter.bi_sector & (bdev_zone_sectors(bio->bi_bdev) - 1) ||
> +	if (!bdev_is_zone_aligned(bio->bi_bdev, bio->bi_iter.bi_sector) ||
>   	    !bio_zone_is_seq(bio))
>   		return BLK_STS_IOERR;

The bdev_is_zone_start() name seems more clear to me than 
bdev_is_zone_aligned(). Has there already been a discussion about which 
name to use for this function?

> +		/*
> +		 * Non power-of-2 zone size support was added to remove the
> +		 * gap between zone capacity and zone size. Though it is technically
> +		 * possible to have gaps in a non power-of-2 device, Linux requires
> +		 * the zone size to be equal to zone capacity for non power-of-2
> +		 * zoned devices.
> +		 */
> +		if (!is_power_of_2(zone->len) && zone->capacity < zone->len) {
> +			pr_warn("%s: Invalid zone capacity for non power of 2 zone size",
> +				disk->disk_name);

Given the severity of this error, shouldn't the zone capacity and length 
be reported in the error message?

Thanks,

Bart.