Re: [PATCH v1 0/5] io_uring: add xattr support

[Clay Harris <bugs@claycon.org>]

On Mon, Nov 29 2021 at 14:12:52 -0800, Stefan Roesch quoth thus:

> This adds the xattr support to io_uring. The intent is to have a more
> complete support for file operations in io_uring.
> 
> This change adds support for the following functions to io_uring:
> - fgetxattr
> - fsetxattr
> - getxattr
> - setxattr

You may wish to consider the following.

Patching for these functions makes for an excellent opportunity
to provide a better interface.  Rather than implement fXetattr
at all, you could enable io_uring to use functions like:

int Xetxattr(int dfd, const char *path, const char *name,
	[const] void *value, size_t size, int flags);

Not only does this simplify the io_uring interface down to two
functions, but modernizes and fixes a deficit in usability.
In terms of io_uring, this is just changing internal interfaces.

Although unnecessary for io_uring, it would be nice to at least
consider what parts of this code could be leveraged for future
Xetxattr2 syscalls.

> Patch 1: fs: make user_path_at_empty() take a struct filename
>   The user_path_at_empty filename parameter has been changed
>   from a const char user pointer to a filename struct. io_uring
>   operates on filenames.
>   In addition also the functions that call user_path_at_empty
>   in namei.c and stat.c have been modified for this change.
> 
> Patch 2: fs: split off setxattr_setup function from setxattr
>   Split off the setup part of the setxattr function
> 
> Patch 3: fs: split off the vfs_getxattr from getxattr
>   Split of the vfs_getxattr part from getxattr. This will
>   allow to invoke it from io_uring.
> 
> Patch 4: io_uring: add fsetxattr and setxattr support
>   This adds new functions to support the fsetxattr and setxattr
>   functions.
> 
> Patch 5: io_uring: add fgetxattr and getxattr support
>   This adds new functions to support the fgetxattr and getxattr
>   functions.
> 
> 
> There are two additional patches:
>   liburing: Add support for xattr api's.
>             This also includes the tests for the new code.
>   xfstests: Add support for io_uring xattr support.
> 
> 
> Stefan Roesch (5):
>   fs: make user_path_at_empty() take a struct filename
>   fs: split off setxattr_setup function from setxattr
>   fs: split off the vfs_getxattr from getxattr
>   io_uring: add fsetxattr and setxattr support
>   io_uring: add fgetxattr and getxattr support
> 
>  fs/internal.h                 |  23 +++
>  fs/io_uring.c                 | 325 ++++++++++++++++++++++++++++++++++
>  fs/namei.c                    |   5 +-
>  fs/stat.c                     |   7 +-
>  fs/xattr.c                    | 114 +++++++-----
>  include/linux/namei.h         |   4 +-
>  include/uapi/linux/io_uring.h |   8 +-
>  7 files changed, 439 insertions(+), 47 deletions(-)
> 
> 
> Signed-off-by: Stefan Roesch <shr@fb.com>
> base-commit: c2626d30f312afc341158e07bf088f5a23b4eeeb
> -- 
> 2.30.2