From 4ffedb343a2fcf008be99c6ae041b0bec26e6b8c Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Mon, 12 Jul 2021 10:12:03 +0800 Subject: [PATCH] mm: make pagecache tagged lookups return only head pages mainline inclusion from mainline-v5.12-rc1 commit c49f50d1983d53871ecc77b60c1fa69a2a5ca6d9 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I3ZE5V CVE: NA ------------------------------------------------- Patch series "Overhaul multi-page lookups for THP", v4. This THP prep patchset changes several page cache iteration APIs to only return head pages. - It's only possible to tag head pages in the page cache, so only return head pages, not all their subpages. - Factor a lot of common code out of the various batch lookup routines - Add mapping_seek_hole_data() - Unify find_get_entries() and pagevec_lookup_entries() - Make find_get_entries only return head pages, like find_get_entry(). These are only loosely connected, but they seem to make sense together as a series. This patch (of 14): Pagecache tags are used for dirty page writeback. Since dirtiness is tracked on a per-THP basis, we only want to return the head page rather than each subpage of a tagged page. All the filesystems which use huge pages today are in-memory, so there are no tagged huge pages today. Link: https://lkml.kernel.org/r/20201112212641.27837-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Jan Kara Reviewed-by: William Kucharski Reviewed-by: Christoph Hellwig Cc: Hugh Dickins Cc: Johannes Weiner Cc: Yang Shi Cc: Dave Chinner Cc: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Liu Shixin Reviewed-by: Tong Tiangen Signed-off-by: Zheng Zengkai --- mm/filemap.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 125b69f59caa..f9454df33dba 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2078,7 +2078,7 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, EXPORT_SYMBOL(find_get_pages_contig); /** - * find_get_pages_range_tag - find and return pages in given range matching @tag + * find_get_pages_range_tag - Find and return head pages matching @tag. * @mapping: the address_space to search * @index: the starting page index * @end: The final page index (inclusive) @@ -2086,8 +2086,9 @@ EXPORT_SYMBOL(find_get_pages_contig); * @nr_pages: the maximum number of pages * @pages: where the resulting pages are placed * - * Like find_get_pages, except we only return pages which are tagged with - * @tag. We update @index to index the next page for the traversal. + * Like find_get_pages(), except we only return head pages which are tagged + * with @tag. @index is updated to the index immediately after the last + * page we return, ready for the next iteration. * * Return: the number of pages which were found. */ @@ -2121,9 +2122,9 @@ unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index, if (unlikely(page != xas_reload(&xas))) goto put_page; - pages[ret] = find_subpage(page, xas.xa_index); + pages[ret] = page; if (++ret == nr_pages) { - *index = xas.xa_index + 1; + *index = page->index + thp_nr_pages(page); goto out; } continue; -- GitLab