Re: [PATCH RFC 1/7] block: move definition of blk_qc_t to types.h

[Mike Snitzer <snitzer@redhat.com>]

On Wed, Dec 23 2020 at  6:26am -0500,
Jeffle Xu <jefflexu@linux.alibaba.com> wrote:

> So that kiocb.ki_cookie can be defined as blk_qc_t, which will enforce
> the encapsulation.
> 
> Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
> ---
>  include/linux/blk_types.h | 2 +-
>  include/linux/fs.h        | 2 +-
>  include/linux/types.h     | 3 +++
>  3 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 866f74261b3b..2e05244fc16d 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -532,7 +532,7 @@ static inline int op_stat_group(unsigned int op)
>  	return op_is_write(op);
>  }
>  
> -typedef unsigned int blk_qc_t;
> +/* Macros for blk_qc_t */
>  #define BLK_QC_T_NONE		-1U
>  #define BLK_QC_T_SHIFT		16
>  #define BLK_QC_T_INTERNAL	(1U << 31)
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index ad4cf1bae586..58db714c4834 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -330,7 +330,7 @@ struct kiocb {
>  	u16			ki_hint;
>  	u16			ki_ioprio; /* See linux/ioprio.h */
>  	union {
> -		unsigned int		ki_cookie; /* for ->iopoll */
> +		blk_qc_t		ki_cookie; /* for ->iopoll */
>  		struct wait_page_queue	*ki_waitq; /* for async buffered IO */
>  	};
>  
> diff --git a/include/linux/types.h b/include/linux/types.h
> index a147977602b5..da5ca7e1bea9 100644
> --- a/include/linux/types.h
> +++ b/include/linux/types.h
> @@ -125,6 +125,9 @@ typedef s64			int64_t;
>  typedef u64 sector_t;
>  typedef u64 blkcnt_t;
>  
> +/* cookie used for IO polling */
> +typedef unsigned int blk_qc_t;
> +
>  /*
>   * The type of an index into the pagecache.
>   */
> -- 
> 2.27.0
> 

Unfortunate that you cannot just include blk_types.h in fs.h; but
vma_is_dax() ruins that for us since commit baabda2614245 ("mm: always
enable thp for dax mappings").

Reviewed-by: Mike Snitzer <snitzer@redhat.com>