On Fri, Jan 20, 2023 at 04:16:55PM +0000, Matthew Wilcox wrote:
> On Fri, Jan 20, 2023 at 04:47:04PM +0300, Dan Carpenter wrote:
> > Hello Dave Chinner,
> >
> > The patch d7b64041164c: "iomap: write iomap validity checks" from Nov
> > 29, 2022, leads to the following Smatch static checker warning:
> >
> > fs/iomap/buffered-io.c:829 iomap_write_iter()
> > error: uninitialized symbol 'folio'.
> >
> > fs/iomap/buffered-io.c
> > 818 if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) {
> > 819 status = -EFAULT;
> > 820 break;
> > 821 }
> > 822
> > 823 status = iomap_write_begin(iter, pos, bytes, &folio);
> > ^^^^^^^
> > The iomap_write_begin() function can succeed without initializing
> > *foliop. It's next to the big comment.
>
> Yes, but if it does, it sets IOMAP_F_STALE
>
> > 824 if (unlikely(status))
> > 825 break;
> > 826 if (iter->iomap.flags & IOMAP_F_STALE)
> > 827 break;
>
> so it breaks out here. Maybe we should return an errno from
> iomap_write_begin() to make life easier for the static checking tools?
>
Thanks for taking a look at this. I say just leave it as-is.
I know how to modify Smatch to handle this correctly, but it's quite a
lot of typing involved.
regards,
dan carpenter
