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

[Andreas Dilger <adilger@dilger.ca>]

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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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