Re: [PATCH 2/8] block: correctly report cache type

[John Garry <john.g.garry@oracle.com>]

On 25/06/2024 15:59, Christoph Hellwig wrote:
> Check the features flag and the override flag, otherwise we're going to
> always report "write through".
> 
> Fixes: 1122c0c1cc71 ("block: move cache control settings out of queue->flags")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   block/blk-sysfs.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 1a984179f3acc5..6db65886e7ed5a 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -453,7 +453,8 @@ static ssize_t queue_io_timeout_store(struct request_queue *q, const char *page,
>   
>   static ssize_t queue_wc_show(struct request_queue *q, char *page)
>   {
> -	if (q->limits.features & BLK_FLAG_WRITE_CACHE_DISABLED)
> +	if (!(q->limits.features & BLK_FEAT_WRITE_CACHE) ||
> +	    (q->limits.flags & BLK_FLAG_WRITE_CACHE_DISABLED))

Could you use blk_queue_write_cache() helper here to reduce duplication?

>   		return sprintf(page, "write through\n");
>   	return sprintf(page, "write back\n");
>   }