Re: [PATCH 13/14] block: Allow REQ_FUA|REQ_READ

Kent Overstreet
2025-03-18T18:00:24Z

On Tue, Mar 18, 2025 at 10:49:25AM -0700, Bart Van Assche wrote:
> On 3/17/25 6:06 PM, Kent Overstreet wrote:
> > What bcachefs is doing is entirely in line with the behaviour the
> > standard states.
>
> I do not agree with the above.
>
> Kent, do you plan to attend the LSF/MM/BPF summit next week? I'm
> wondering whether allowing REQ_FUA|REQ_READ would be a good topic
> for that summit.

No, I won't be there this year. And I don't think it'd be the right
forum for arguing over the meaning of an obscure line in the NVME spec,
anyways :)

It's certainly not in dispute that read fua is a documented, legitimate
command, so there's no reason for the block layer to be rejecting it.

Whether it has exactly the behaviour we want isn't a critical issue that
has to be determined right now. The starting point for that will be to
test device behaviour (with some simple performance tests, like I
mentioned), and anyways it's outside the scope of the block layer.