Re: [PATCH v3] fuse: Allow page aligned writes

[Bernd Schubert <bernd.schubert@fastmail.fm>]

On 8/29/24 15:39, Miklos Szeredi wrote:
> On Thu, 29 Aug 2024 at 15:05, Bernd Schubert <bschubert@ddn.com> wrote:
>>
>> On 8/29/24 14:46, Miklos Szeredi wrote:
>>> On Mon, 12 Aug 2024 at 18:37, Bernd Schubert <bernd.schubert@fastmail.fm> wrote:
>>>>
>>>> Sorry, I had sent out the wrong/old patch file - it doesn't have one change
>>>> (handling of already aligned buffers).
>>>> Shall I sent v4? The correct version is below
>>>>
>>>> ---
>>>>
>>>> From: Bernd Schubert <bschubert@ddn.com>
>>>> Date: Fri, 21 Jun 2024 11:51:23 +0200
>>>> Subject: [PATCH v3] fuse: Allow page aligned writes
>>>>
>>>> Write IOs should be page aligned as fuse server
>>>> might need to copy data to another buffer otherwise in
>>>> order to fulfill network or device storage requirements.
>>>
>>> Okay.
>>>
>>> So why not align the buffer in userspace so the payload of the write
>>> request lands on a page boundary?
>>>
>>> Just the case that you have noted in the fuse_copy_align() function.
>>
>> How would you do that with splice?
> 
> I would have thought that splice already honored page boundaries, but
> maybe commit 0c4bcfdecb1a ("fuse: fix pipe buffer lifetime for
> direct_io") broke something there.  Should be fixable easily without
> need to change the interface, because splice is free to start a new
> buffer at any point.

Actually my mistake, I had thought that splice has the same issue and I
really thought I had tested it, but actually splice works fine and has
aligned pages.


Thanks,
Bernd