Re: [patch 8/8] consolidate generic_writepages and mpage_writepages fix

Miklos Szeredi
2007-03-07T21:26:40Z

> > From: Miklos Szeredi <mszeredi@suse.cz>
> >
> > Fix NULL pointer dereference in __mpage_writepage. This probably
> > doesn't matter in practice, but this is the original behavior.
> >
> > Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
> > ---
> >
> > Index: linux/fs/mpage.c
> > ===================================================================
> > --- linux.orig/fs/mpage.c 2007-03-06 17:30:09.000000000 +0100
> > +++ linux/fs/mpage.c 2007-03-06 17:30:33.000000000 +0100
> > @@ -662,7 +662,7 @@ confused:
> > if (bio)
> > bio = mpage_bio_submit(WRITE, bio);
> >
> > - if (mpd->use_writepage) {
> > + if (mpd->use_writepage && mapping->a_ops->writepage) {
> > ret = mapping->a_ops->writepage(page, wbc);
> > } else {
> > ret = -EAGAIN;
> >
> > --
>
> I'm inclined to leave the code as-is, as an optimisation. If it
> blows up then it'd be cleaner to change the caller (mpage_writepages)
> to do
>
> .use_writepage = (writepage != NULL),
>
> ?

It seems all in-tree uses of mpage_writepages define ->writepage() so
it should be safe to drop this patch.

Thanks,
Miklos