Re: [PATCH v2 03/11] block: introduce BIO_ZONE_WRITE_LOCKED bio flag

[Hannes Reinecke <hare@suse.de>]

On 5/20/21 6:22 AM, Damien Le Moal wrote:
> Introduce the BIO flag BIO_ZONE_WRITE_LOCKED to indicate that a BIO owns
> the write lock of the zone it is targeting. This is the counterpart of
> the struct request flag RQF_ZONE_WRITE_LOCKED.
> 
> This new BIO flag is reserved for now for zone write locking control
> for device mapper targets exposing a zoned block device. Since in this
> case, the lock flag must not be propagated to the struct request that
> will be used to process the BIO, a BIO private flag is used rather than
> changing the RQF_ZONE_WRITE_LOCKED request flag into a common REQ_XXX
> flag that could be used for both BIO and request. This avoids conflicts
> down the stack with the block IO scheduler zone write locking
> (in mq-deadline).
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>   include/linux/blk_types.h | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index db026b6ec15a..e5cf12f102a2 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -304,6 +304,7 @@ enum {
>   	BIO_CGROUP_ACCT,	/* has been accounted to a cgroup */
>   	BIO_TRACKED,		/* set if bio goes through the rq_qos path */
>   	BIO_REMAPPED,
> +	BIO_ZONE_WRITE_LOCKED,	/* Owns a zoned device zone write lock */
>   	BIO_FLAG_LAST
>   };
>   
> 
I would have merged this with the patch actually using it, but this is 
probably a personal preference.

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

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