Subject: Re: linux-next: manual merge of the akpm-current tree with the btrfs tree

From: David Sterba <[email-masked]>
Date: Mon, 1 Mar 2021 12:04:27 +0100

On Fri, Feb 26, 2021 at 06:16:26AM +0100, Christoph Hellwig wrote:
> On Fri, Feb 26, 2021 at 10:32:50AM +1100, Stephen Rothwell wrote:
> > > >  -	return filemap_read(iocb, to, ret);
> > > >  +	if (iocb->ki_flags & IOCB_NOWAIT)
> > > >  +		iocb->ki_flags |= IOCB_NOIO;
> > > >  +
> > > > - 	ret = generic_file_buffered_read(iocb, to, ret);
> > > > ++	ret = filemap_read(iocb, to, ret);
> > > >  +
> > > >  +	if (iocb->ki_flags & IOCB_NOWAIT) {
> > > >  +		iocb->ki_flags &= ~IOCB_NOIO;
> > > >  +		if (ret == 0)
> > > >  +			ret = -EAGAIN;
> > > >  +	}
> > > >  +
> > > >  +	return ret;
> > > >   }
> 
> I think the above code looks completely bogus.  Instead whatever code
> in btrfs hecks for IOCB_NOIO to avoid blocking readahead should also
> check IOCB_NOWAIT.

Thanks for the comment, I've removed the patch from for-next and
notified the authors.