On Mon, Jun 13, 2022 at 07:30:22PM +0100”, Matthew Wilcox wrote:
> On Mon, Jun 13, 2022 at 11:08:58AM -0700, Mike Kravetz wrote:
> > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> > index eca1d0fabd7e..b0d0947a7e9b 100644
> > --- a/fs/hugetlbfs/inode.c
> > +++ b/fs/hugetlbfs/inode.c
> > @@ -584,41 +584,79 @@ static void hugetlb_vmtruncate(struct inode *inode, loff_t offset)
> > remove_inode_hugepages(inode, offset, LLONG_MAX);
> > }
> >
> > +static void hugetlbfs_zero_partial_page(struct hstate *h,
> > + struct address_space *mapping,
> > + unsigned long start,
>
> This should be loff_t. Otherwise we can truncate on 32-bit machines.
>
Thanks! I missed that.
> > + unsigned long end)
> > +{
> > + pgoff_t idx = start >> huge_page_shift(h);
> > + struct page *page;
> > +
> > + page = find_lock_page(mapping, idx);
> > + if (!page)
> > + return;
> > +
> > + start = start & ~huge_page_mask(h);
> > + end = end & ~huge_page_mask(h);
> > + if (!end)
> > + end = huge_page_size(h);
> > +
> > + zero_user_segment(page, (unsigned int)start, (unsigned int)end);
> > +
> > + unlock_page(page);
> > + put_page(page);
>
> We haven't started converting hugetlbfs to folios yet, but here's how
> that would look (which will save us converting it later):
>
> folio = filemap_lock_folio(mapping, idx);
> if (!folio)
> return;
> ...
> folio_zero_segment(folio, start, end);
> folio_unlock(folio);
> folio_put(folio);
>
> Pretty much a 1-for-1 replacement.
>
Great. The folio conversion is on my todo list, but I would not be
offended if someone beat me to it.
--
Mike Kravetz
