Re: [PATCH] io_uring/cmd: let cmds to know about dying task

[David Sterba <dsterba@suse.cz>]

On Mon, Nov 04, 2024 at 10:31:19AM -0700, Jens Axboe wrote:
> On 11/4/24 9:47 AM, Pavel Begunkov wrote:
> > On 11/4/24 16:15, Jens Axboe wrote:
> >> On 11/4/24 9:12 AM, Pavel Begunkov wrote:
> >>> When the taks that submitted a request is dying, a task work for that
> >>> request might get run by a kernel thread or even worse by a half
> >>> dismantled task. We can't just cancel the task work without running the
> >>> callback as the cmd might need to do some clean up, so pass a flag
> >>> instead. If set, it's not safe to access any task resources and the
> >>> callback is expected to cancel the cmd ASAP.
> >>>
> >>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> >>> ---
> >>>
> >>> Made a bit fancier to avoid conflicts. Mark, as before I'd suggest you
> >>> to take it and send together with the fix.
> >>
> >> That's fine, or we can just take it through the io_uring tree, it's not
> >> like this matters as both will land before -rc1.
> > 
> > There should be a btrfs patch that depends on it and I would hope
> > it gets squashed into the main patchset or at least goes into the
> > same pull and not delayed to rc2.
> 
> Right, all I'm saying is that both will land in -rc1 and it doesn't
> really matter. Even if it's -rc2 it's not like a potential breakage with
> this for certain exiting conditions is an issue. All that really matters
> is that the final release is fine.
> 
> But like I said, I don't really care - it can go through the btrfs tree
> as-is, or I can take it and it'll land in -rc1. If the latter, then I'd
> just modify it to use io_should_terminate_tw() fro the get-go, if it
> goes via the btrfs tree, then we can do a separate patch for that after
> the fact.
> 
> I just need to know what the btrfs people intend to do here, so I can
> plan accordingly.

I'll add it to btrfs tree, branch for-next and it will be in the main
merge window pull request.