Re: [PATCH 5/8] fs: add project support to statx

[Dave Chinner <david@fromorbit.com>]

On Fri, Mar 01, 2019 at 11:05:38PM +0900, Wang Shilong wrote:
> From: Wang Shilong <wshilong@ddn.com>
> 
> From: Wang Shilong <wshilong@ddn.com>
> 
> Extend statx to support project ID and inherit attribute.
> 
> Signed-off-by: Wang Shilong <wshilong@ddn.com>
> ---
>  fs/stat.c                       | 1 +
>  include/linux/stat.h            | 2 ++
>  include/uapi/linux/stat.h       | 8 ++++++--
>  tools/include/uapi/linux/stat.h | 8 ++++++--
>  4 files changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/stat.c b/fs/stat.c
> index adbfcd86c81b..82d855c4647c 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -551,6 +551,7 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
>  	tmp.stx_rdev_minor = MINOR(stat->rdev);
>  	tmp.stx_dev_major = MAJOR(stat->dev);
>  	tmp.stx_dev_minor = MINOR(stat->dev);
> +	tmp.stx_projid = (u32)from_kprojid(&init_user_ns, stat->projid);

If we are not in the init_user_ns, the project ID should be zero -
it should not be changeable or visible at all. I'm guessing the next
patches enforce this?

Regardless, the cast to (u32) should not be necessary.

Hmmmm.

/me looks at from_kprojid_munged() and thinks it needs to be nuked
from orbit. There is no such thing as an "overflow" project ID, and
65534 is a valid XFS project ID.


> diff --git a/tools/include/uapi/linux/stat.h b/tools/include/uapi/linux/stat.h
> index 7b35e98d3c58..21b542b3b061 100644
> --- a/tools/include/uapi/linux/stat.h
> +++ b/tools/include/uapi/linux/stat.h
> @@ -123,7 +123,9 @@ struct statx {
>  	__u32	stx_dev_major;	/* ID of device containing file [uncond] */
>  	__u32	stx_dev_minor;
>  	/* 0x90 */
> -	__u64	__spare2[14];	/* Spare space for future expansion */
> +	__u32   stx_projid;     /* Project ID of file */
> +	__u32   __spare1[1];
> +	__u64   __spare2[13];   /* Spare space for future expansion */
>  	/* 0x100 */
>  };
>  
> @@ -148,7 +150,8 @@ struct statx {
>  #define STATX_BLOCKS		0x00000400U	/* Want/got stx_blocks */
>  #define STATX_BASIC_STATS	0x000007ffU	/* The stuff in the normal stat struct */
>  #define STATX_BTIME		0x00000800U	/* Want/got stx_btime */
> -#define STATX_ALL		0x00000fffU	/* All currently supported flags */
> +#define STATX_PROJID		0x00001000U	/* Want/Got stx_projid */
> +#define STATX_ALL		0x00001fffU	/* All currently supported flags */
>  #define STATX__RESERVED		0x80000000U	/* Reserved for future struct statx expansion */
>  
>  /*
> @@ -170,5 +173,6 @@ struct statx {
>  
>  #define STATX_ATTR_AUTOMOUNT		0x00001000 /* Dir: Automount trigger */
>  
> +#define STATX_ATTR_PROJINHERIT		0x00002000 /* [I] File project inherit is set */
							          ^^^^

The project ID inherit attribute is only valid for directories, not
files. Also, should probably be named STATX_ATTR_PROJID_INHERIT.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com