Re: [PATCH] btrfs: add io_uring interface for encoded reads

[Pavel Begunkov <asml.silence@gmail.com>]

On 8/12/24 17:58, David Sterba wrote:
> On Mon, Aug 12, 2024 at 05:10:15PM +0100, Pavel Begunkov wrote:
>> And the last point, I'm surprised there are two versions of
>> btrfs_ioctl_encoded_io_args. Maybe, it's a good moment to fix it if
>> we're creating a new interface.
>>
>> E.g. by adding a new structure defined right with u64 and such, use it
>> in io_uring, and cast to it in the ioctl code when it's x64 (with
>> a good set of BUILD_BUG_ON sprinkled) and convert structures otherwise?
> 
> If you mean the 32bit version of the ioctl struct
> (btrfs_ioctl_encoded_io_args_32), I don't think we can fix it. It's been

Right, I meant btrfs_ioctl_encoded_io_args_32. And to clarify, nothing
can be done for the ioctl(2) part, I only suggested to have a single
structure when it comes to io_uring.

> there from the beginning and it's not a mistake. I don't remember the
> details why and only vaguely remember that I'd asked why we need it.
> Similar 64/32 struct is in the send ioctl but that was a mistake due to
> a pointer being passed in the structure and that needs to be handled due
> to different type width.

Would be interesting to learn why, maybe Omar remembers? Only two
fields are not explicitly sized, both could've been just u64.
The structure iov points to (struct iovec) would've had a compat
flavour, but that doesn't require a separate
btrfs_ioctl_encoded_io_args.

-- 
Pavel Begunkov