Re: [PATCH 19/26] block: move the nowait flag to queue_limits

[Damien Le Moal <dlemoal@xxxxxxxxxx>]

On 6/11/24 2:19 PM, Christoph Hellwig wrote:
> Move the nowait flag into the queue_limits feature field so that it
> can be set atomically and all I/O is frozen when changing the flag.
> 
> Stacking drivers are simplified in that they now can simply set the
> flag, and blk_stack_limits will clear it when the features is not
> supported by any of the underlying devices.
> 
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>


> @@ -1825,9 +1815,7 @@ int dm_table_set_restrictions(struct dm_table *t, 
> struct request_queue *q,
>       int r;
>  
>       if (dm_table_supports_nowait(t))
> -             blk_queue_flag_set(QUEUE_FLAG_NOWAIT, q);
> -     else
> -             blk_queue_flag_clear(QUEUE_FLAG_NOWAIT, q);
> +             limits->features &= ~BLK_FEAT_NOWAIT;

Shouldn't you set the flag here instead of clearing it ?

-- 
Damien Le Moal
Western Digital Research