Re: [PATCH v2 01/17] mm: drop "wait" parameter from write_one_page

From: Jeff Layton
Date: Wed Apr 12 2017 - 10:34:56 EST


On Wed, 2017-04-12 at 07:27 -0700, Matthew Wilcox wrote:
> On Wed, Apr 12, 2017 at 08:05:58AM -0400, Jeff Layton wrote:
> > The callers all set it to 1. Also, make it clear that this function will
> > not set any sort of AS_* error, and that the caller must do so if
> > necessary. No existing caller uses this on normal files, so none of them
> > need it.
>
> So ... anyone who doesn't check the error code loses an error indication.
>
> > +++ b/fs/jfs/jfs_metapage.c
> > @@ -711,7 +711,7 @@ void force_metapage(struct metapage *mp)
> > get_page(page);
> > lock_page(page);
> > set_page_dirty(page);
> > - write_one_page(page, 1);
> > + write_one_page(page);
> > clear_bit(META_forcewrite, &mp->flag);
> > put_page(page);
> > }
> > @@ -756,7 +756,7 @@ void release_metapage(struct metapage * mp)
> > set_page_dirty(page);
> > if (test_bit(META_sync, &mp->flag)) {
> > clear_bit(META_sync, &mp->flag);
> > - write_one_page(page, 1);
> > + write_one_page(page);
> > lock_page(page); /* write_one_page unlocks the page */
> > }
> > } else if (mp->lsn) /* discard_metapage doesn't remove it */
>
> This looks quite bad. If my reading is right, these pages are part of
> the journal. I think somebody who knows JFS needs to figure out what
> should happen here ...
>
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 00a8fa7e366a..f25b76486645 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -2187,7 +2187,7 @@ extern void filemap_map_pages(struct vm_fault *vmf,
> > extern int filemap_page_mkwrite(struct vm_fault *vmf);
> >
> > /* mm/page-writeback.c */
> > -int write_one_page(struct page *page, int wait);
> > +int write_one_page(struct page *page);
> > void task_dirty_inc(struct task_struct *tsk);
> >
> > /* readahead.c */
>
> Can we mark this as __must_check so JFS picks up a couple of warnings?
>
> Reviewed-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>

Good idea -- I'll roll that in with this patch.
--
Jeff Layton <jlayton@xxxxxxxxxx>