Re: [PATCH] iomap: Make sure iomap_end is called after iomap_begin

From: Andreas Gruenbacher <agruenba@redhat.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
	Christoph Hellwig <hch@infradead.org>,
	linux-xfs@vger.kernel.org,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Bob Peterson <rpeterso@redhat.com>
Subject: Re: [PATCH] iomap: Make sure iomap_end is called after iomap_begin
Date: Thu, 18 Jun 2020 14:37:37 +0200	[thread overview]
Message-ID: <CAHc6FU5x8+54zX5NWEDdsf5HV5qXLnjS1SM+oYmX1yMrh_mDfA@mail.gmail.com> (raw)
In-Reply-To: <20200618123227.GO8681@bombadil.infradead.org>

On Thu, Jun 18, 2020 at 2:32 PM Matthew Wilcox <willy@infradead.org> wrote:
> On Wed, Jun 17, 2020 at 06:39:01PM -0700, Darrick J. Wong wrote:
> > > -   if (WARN_ON(iomap.offset > pos))
> > > -           return -EIO;
> > > -   if (WARN_ON(iomap.length == 0))
> > > -           return -EIO;
> > > +   if (WARN_ON(iomap.offset > pos) || WARN_ON(iomap.length == 0)) {
> >
> > Why combine these WARN_ON?  Before, you could distinguish between your
> > iomap_begin method returning zero length vs. bad offset.
>
> Does it matter?  They're both the same problem -- the filesystem has
> returned an invalid iomap.  I'd go further and combine the two:
>
>         if (WARN_ON(iomap.offset > pos || iomap.length == 0)) {
>
> that'll save a few bytes of .text

That would be fine by me as well. Christoph may have wanted separate
warnings for a particular reason though.

Andreas