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?
> --> 829 page = folio_file_page(folio, pos >> PAGE_SHIFT);
> ^^^^^
>
> 830 if (mapping_writably_mapped(mapping))
> 831 flush_dcache_page(page);
