linux-kernel - Re: [PATCH 03/21] fs/bdev: Add atomic write support info to statx

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Message-ID: <20230929224922.GB11839@google.com>
Date:   Fri, 29 Sep 2023 22:49:22 +0000
From:   Eric Biggers <ebiggers@...nel.org>
To:     John Garry <john.g.garry@...cle.com>
Cc:     axboe@...nel.dk, kbusch@...nel.org, hch@....de, sagi@...mberg.me,
        jejb@...ux.ibm.com, martin.petersen@...cle.com, djwong@...nel.org,
        viro@...iv.linux.org.uk, brauner@...nel.org,
        chandan.babu@...cle.com, dchinner@...hat.com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, tytso@....edu, jbongio@...gle.com,
        linux-api@...r.kernel.org,
        Prasad Singamsetty <prasad.singamsetty@...cle.com>
Subject: Re: [PATCH 03/21] fs/bdev: Add atomic write support info to statx

On Fri, Sep 29, 2023 at 10:27:08AM +0000, John Garry wrote:
> diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
> index 7cab2c65d3d7..c99d7cac2aa6 100644
> --- a/include/uapi/linux/stat.h
> +++ b/include/uapi/linux/stat.h
> @@ -127,7 +127,10 @@ struct statx {
>  	__u32	stx_dio_mem_align;	/* Memory buffer alignment for direct I/O */
>  	__u32	stx_dio_offset_align;	/* File offset alignment for direct I/O */
>  	/* 0xa0 */
> -	__u64	__spare3[12];	/* Spare space for future expansion */
> +	__u32	stx_atomic_write_unit_max;
> +	__u32	stx_atomic_write_unit_min;

Maybe min first and then max?  That seems a bit more natural, and a lot of the
code you've written handle them in that order.

> +#define STATX_ATTR_WRITE_ATOMIC		0x00400000 /* File supports atomic write operations */

How would this differ from stx_atomic_write_unit_min != 0?

- Eric