Re: [PATCH v3 2/5] block: Introduce bio_needs_zone_write_plugging()

[Johannes Thumshirn <Johannes.Thumshirn@wdc.com>]

On 25.06.25 11:44, Damien Le Moal wrote:
> static inline bool bio_needs_zone_write_plugging(struct bio *bio)
> +{
> +	enum req_op op = bio_op(bio);
> +
> +	/*
> +	 * Only zoned block devices have a zone write plug hash table. But not
> +	 * all of them have one (e.g. DM devices may not need one).
> +	 */
> +	if (!bio->bi_bdev->bd_disk->zone_wplugs_hash)
> +		return false;
> +
> +	/* Only write operations need zone write plugging. */
> +	if (!op_is_write(op))
> +		return false;
> +
> +	/* Ignore empty flush */
> +	if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
> +		return false;
> +
> +	/* Ignore BIOs that already have been handled by zone write plugging. */
> +	if (bio_flagged(bio, BIO_ZONE_WRITE_PLUGGING))
> +		return false;
> +
> +	/*
> +	 * All zone write operations must be handled through zone write plugging
> +	 * using blk_zone_plug_bio().
> +	 */
> +	switch (op) {
> +	case REQ_OP_ZONE_APPEND:
> +	case REQ_OP_WRITE:
> +	case REQ_OP_WRITE_ZEROES:
> +	case REQ_OP_ZONE_FINISH:
> +	case REQ_OP_ZONE_RESET:
> +	case REQ_OP_ZONE_RESET_ALL:
> +		return true;
> +	default:
> +		return false;
> +	}

Maybe this is bikeshedding territory here but I'd move the long pointer 
chase 'bio->bi_bdev->bd_disk->zone_wplugs_hash' later into the function.
At least after the op_is_write() check, so that reads don't get the 
pointer chase.