Re: [PATCH 1/2] block: fix error code for zone-append

[Kanchan Joshi]

On Fri, Jul 03, 2020 at 05:29:50AM +0000, Damien Le Moal wrote:
> On 2020/07/03 0:42, Kanchan Joshi wrote:
> > avoid returning success when it should report failure, preventing
> > odd behavior in caller.
>
> You can be more precise here: the odd behavior is an infinite loop in
> bio_iov_iter_get_pages() whcih is is the only user of __bio_iov_append_get_pages().
Sure. Kept that in cover letter, but missed here.
> > Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
> > Signed-off-by: Selvakumar S <selvakuma.s1@xxxxxxxxxxx>
> > Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
> > Signed-off-by: Javier Gonzalez <javier.gonz@xxxxxxxxxxx>
> > ---
> >  block/bio.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/block/bio.c b/block/bio.c
> > index a7366c0..0cecdbc 100644
> > --- a/block/bio.c
> > +++ b/block/bio.c
> > @@ -1044,7 +1044,7 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
> >  	size_t offset;
> >
> >  	if (WARN_ON_ONCE(!max_append_sectors))
> > -		return 0;
> > +		return -EINVAL;
> >
> >  	/*
> >  	 * Move page array up in the allocated memory for the bio vecs as far as
>
> Note: the odd behavior mentioned in the commit message cannot currently be
> triggered since only zonefs issues REQ_OP_ZONE_APPEND BIOs so we are guaranteed
> that max_append_sectors is not 0 in that case. But this fix certainly makes
> things more solid. So:
Yes, zonefs will not run into this. Future users of zone-append may. I
encountered this endless loop while testing user zone-append path.
> Reviewed-by: Damien Le Moal <damien.lemoal@xxxxxxx>
>
> --
> Damien Le Moal
> Western Digital Research