On Tue, Jun 06, 2023 at 08:13:55AM +0200, Richard Weinberger wrote:
> Matthew,
>
> ----- Ursprüngliche Mail -----
> > Von: "Matthew Wilcox" <willy@xxxxxxxxxxxxx>
> > len is folio_size(), which is not 0.
> >
> > len = offset_in_folio(folio, i_size);
>
> offset_in_folio(folio, i_size) can give 0.
Oh! There is a bug, because it shouldn't get here!
/* Is the folio fully inside i_size? */
if (folio_pos(folio) + len < i_size) {
should be:
/* Is the folio fully inside i_size? */
if (folio_pos(folio) + len <= i_size) {
right? Consider a file with i_size 4096. its single-page folio will
have a pos of 0 and a length of 4096. so it should be written back by
the first call to do_writepage(), not the case where the folio straddles
i_size.
