Am Di., 23. Juni 2020 um 12:38 Uhr schrieb Christoph Hellwig
<hch@xxxxxxxxxxxxx>:
> On Mon, Jun 22, 2020 at 11:07:59AM +0200, Andreas Gruenbacher wrote:
> > On Fri, Jun 19, 2020 at 3:25 PM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
> > > On Thu, Jun 18, 2020 at 02:24:08PM +0200, Andreas Gruenbacher wrote:
> > > > Make sure iomap_end is always called when iomap_begin succeeds.
> > > >
> > > > Without this fix, iomap_end won't be called when a filesystem's
> > > > iomap_begin operation returns an invalid mapping, bypassing any
> > > > unlocking done in iomap_end. With this fix, the unlocking would
> > > > at least still happen.
> > > >
> > > > This iomap_apply bug was found by Bob Peterson during code review.
> > > > It's unlikely that such iomap_begin bugs will survive to affect
> > > > users, so backporting this fix seems unnecessary.
> > > >
> > > > Fixes: ae259a9c8593 ("fs: introduce iomap infrastructure")
> > > > Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
> > > > ---
> > > > fs/iomap/apply.c | 10 ++++++----
> > > > 1 file changed, 6 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c
> > > > index 76925b40b5fd..32daf8cb411c 100644
> > > > --- a/fs/iomap/apply.c
> > > > +++ b/fs/iomap/apply.c
> > > > @@ -46,10 +46,11 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
> > > > ret = ops->iomap_begin(inode, pos, length, flags, &iomap, &srcmap);
> > > > if (ret)
> > > > return ret;
> > > > - 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)) {
> > > > + written = -EIO;
> > > > + goto out;
> > > > + }
> > >
> > > As said before please don't merge these for no good reason.
> >
> > I really didn't expect this tiny patch to require much discussion at
> > all, but just to be clear ... do you actually object to this very
> > patch that explicitly doesn't merge the two checks and keeps them on
> > two separate lines so that the warning messages will report different
> > line numbers, or are you fine with that?
>
> Yes, it merges the WARN_ONs, and thus reduces their usefulness. How
> about a patch that just fixes your reported issue insted of messing up
> other things for no good reason?
So you're saying you prefer this:
+ if (WARN_ON(iomap.offset > pos)) {
+ written = -EIO;
+ goto out;
+ }
+ if (WARN_ON(iomap.length == 0)) {
+ written = -EIO;
+ goto out;
+ }
to this:
+ if (WARN_ON(iomap.offset > pos) ||
+ WARN_ON(iomap.length == 0)) {
+ written = -EIO;
+ goto out;
+ }
Well fine, you don't need to accuse me of messing up things for that.
Andreas
