linux-kernel - Re: [PATCH 2/7] block: add a new helper bdev_{is_zone_start, offset_from_zone

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Message-ID: <32aaa034-dc39-75dd-f4ec-e0e5ef9dd29c@opensource.wdc.com>
Date:   Fri, 6 Jan 2023 20:00:38 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Pankaj Raghav <p.raghav@...sung.com>, axboe@...nel.dk
Cc:     kernel@...kajraghav.com, linux-kernel@...r.kernel.org,
        hare@...e.de, bvanassche@....org, snitzer@...nel.org,
        dm-devel@...hat.com, linux-nvme@...ts.infradead.org, hch@....de,
        linux-block@...r.kernel.org, gost.dev@...sung.com
Subject: Re: [PATCH 2/7] block: add a new helper bdev_{is_zone_start,
 offset_from_zone_start}

On 1/6/23 17:33, Pankaj Raghav wrote:
> Instead of open coding to check for zone start, add a helper to improve
> readability and store the logic in one place.
> 
> bdev_offset_from_zone_start() will be used later in the series.
> 
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> ---
>  block/blk-core.c       |  2 +-
>  block/blk-zoned.c      |  4 ++--
>  include/linux/blkdev.h | 18 ++++++++++++++++++
>  3 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 9321767470dc..0405b3144e7a 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -573,7 +573,7 @@ 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_start(bio->bi_bdev, bio->bi_iter.bi_sector) ||
>  	    !bio_zone_is_seq(bio))
>  		return BLK_STS_IOERR;
>  
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index db829401d8d0..614b575be899 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -277,10 +277,10 @@ int blkdev_zone_mgmt(struct block_device *bdev, enum req_op op,
>  		return -EINVAL;
>  
>  	/* Check alignment (handle eventual smaller last zone) */
> -	if (sector & (zone_sectors - 1))
> +	if (!bdev_is_zone_start(bdev, sector))
>  		return -EINVAL;
>  
> -	if ((nr_sectors & (zone_sectors - 1)) && end_sector != capacity)
> +	if (!bdev_is_zone_start(bdev, nr_sectors) && end_sector != capacity)
>  		return -EINVAL;
>  
>  	/*
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 0e40b014c40b..04b7cbfd7a2a 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -715,6 +715,7 @@ static inline unsigned int disk_zone_no(struct gendisk *disk, sector_t sector)
>  {
>  	return 0;
>  }
> +

whiteline change

>  static inline unsigned int bdev_max_open_zones(struct block_device *bdev)
>  {
>  	return 0;
> @@ -1304,6 +1305,23 @@ static inline sector_t bdev_zone_sectors(struct block_device *bdev)
>  	return q->limits.chunk_sectors;
>  }
>  
> +static inline sector_t bdev_offset_from_zone_start(struct block_device *bdev,
> +						   sector_t sec)
> +{
> +	if (!bdev_is_zoned(bdev))

this helper should never be called outside of code supporting zones. So
why this check ?

> +		return 0;
> +
> +	return sec & (bdev_zone_sectors(bdev) - 1);
> +}
> +
> +static inline bool bdev_is_zone_start(struct block_device *bdev, sector_t sec)
> +{
> +	if (!bdev_is_zoned(bdev))
> +		return false;

Same here.

> +
> +	return bdev_offset_from_zone_start(bdev, sec) == 0;
> +}
> +
>  static inline int queue_dma_alignment(const struct request_queue *q)
>  {
>  	return q ? q->limits.dma_alignment : 511;

-- 
Damien Le Moal
Western Digital Research