Re: [PATCHv12 01/12] fs: add write stream information to statx

[Christian Brauner <brauner@kernel.org>]

On Fri, Dec 06, 2024 at 02:17:50PM -0800, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Add new statx field to report the maximum number of write streams
> supported and the granularity for them.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> [hch: rename hint to stream, add granularity]
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/stat.c                 | 2 ++
>  include/linux/stat.h      | 2 ++
>  include/uapi/linux/stat.h | 7 +++++--
>  3 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/stat.c b/fs/stat.c
> index 0870e969a8a0b..00e4598b1ff25 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -729,6 +729,8 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
>  	tmp.stx_atomic_write_unit_min = stat->atomic_write_unit_min;
>  	tmp.stx_atomic_write_unit_max = stat->atomic_write_unit_max;
>  	tmp.stx_atomic_write_segments_max = stat->atomic_write_segments_max;
> +	tmp.stx_write_stream_granularity = stat->write_stream_granularity;
> +	tmp.stx_write_stream_max = stat->write_stream_max;
>  
>  	return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
>  }
> diff --git a/include/linux/stat.h b/include/linux/stat.h
> index 3d900c86981c5..36d4dfb291abd 100644
> --- a/include/linux/stat.h
> +++ b/include/linux/stat.h
> @@ -57,6 +57,8 @@ struct kstat {
>  	u32		atomic_write_unit_min;
>  	u32		atomic_write_unit_max;
>  	u32		atomic_write_segments_max;
> +	u32		write_stream_granularity;
> +	u16		write_stream_max;
>  };
>  
>  /* These definitions are internal to the kernel for now. Mainly used by nfsd. */
> diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
> index 887a252864416..547c62a1a3a7c 100644
> --- a/include/uapi/linux/stat.h
> +++ b/include/uapi/linux/stat.h
> @@ -132,9 +132,11 @@ struct statx {
>  	__u32	stx_atomic_write_unit_max;	/* Max atomic write unit in bytes */
>  	/* 0xb0 */
>  	__u32   stx_atomic_write_segments_max;	/* Max atomic write segment count */
> -	__u32   __spare1[1];
> +	__u32   stx_write_stream_granularity;
>  	/* 0xb8 */
> -	__u64	__spare3[9];	/* Spare space for future expansion */
> +	__u16   stx_write_stream_max;
> +	__u16	__sparse2[3];
> +	__u64	__spare3[8];	/* Spare space for future expansion */
>  	/* 0x100 */
>  };

Once you're ready to merge, let me know so I can give you a stable
branch with the fs changes.

>  
> @@ -164,6 +166,7 @@ struct statx {
>  #define STATX_MNT_ID_UNIQUE	0x00004000U	/* Want/got extended stx_mount_id */
>  #define STATX_SUBVOL		0x00008000U	/* Want/got stx_subvol */
>  #define STATX_WRITE_ATOMIC	0x00010000U	/* Want/got atomic_write_* fields */
> +#define STATX_WRITE_STREAM	0x00020000U	/* Want/got write_stream_* */
>  
>  #define STATX__RESERVED		0x80000000U	/* Reserved for future struct statx expansion */
>  
> -- 
> 2.43.5
> 

On Fri, Dec 06, 2024 at 02:17:51PM -0800, Keith Busch wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> Prepare for io_uring passthrough of write streams. The write stream
> field in the kiocb structure fits into an existing 2-byte hole, so its
> size is not changed.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  include/linux/fs.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 2cc3d45da7b01..26940c451f319 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -373,6 +373,7 @@ struct kiocb {
>  	void			*private;
>  	int			ki_flags;
>  	u16			ki_ioprio; /* See linux/ioprio.h */
> +	u8			ki_write_stream;
>  	union {
>  		/*
>  		 * Only used for async buffered reads, where it denotes the
> -- 
> 2.43.5
>