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

Andreas Dilger
2021-11-30T03:16:08Z

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> On Nov 29, 2021, at 6:08 PM, Clay Harris <bugs@claycon.org> wrote:
>
> 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);

This would naturally be named "...xattrat()"?

> 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.

Even better would be the ability to get/set an array of xattrs in
one call, to avoid repeated path lookups in the common case of
handling multiple xattrs on a single file.

> 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

Cheers, Andreas

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