re-enable IOCB_NOWAIT writes to files v2

[Christoph Hellwig]

On Tue, Nov 25, 2025 at 10:18:32AM +0100, Christian Brauner wrote:
> It's a bit too close to the merge window for my taste and we have about
> 17 pull request topics for this cycle already.
> 
> So I'll take this for vfs-6.20.iomap. As usual I'll create that branch
> now so that the patches don't get lost and will rebase once v6.19-rc1 is
> out.

I can understand that.  Although it would be nice to get the nfsd
and btrfs fixes in, i.e. patch 1-4 (and 5/6 are trivial and would be
neat as well).  I'll need to resend the others anyway based on the
(minor) review feedback, which I'll do right after -rc1.