From 5fd4ca2d84b249f0858ce28cf637cf25b61a398f Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Mon, 13 May 2019 17:16:44 -0700 Subject: mm: page cache: store only head pages in i_pages Transparent Huge Pages are currently stored in i_pages as pointers to consecutive subpages. This patch changes that to storing consecutive pointers to the head page in preparation for storing huge pages more efficiently in i_pages. Large parts of this are "inspired" by Kirill's patch https://lore.kernel.org/lkml/20170126115819.58875-2-kirill.shutemov@linux.intel.com/ [willy@infradead.org: fix swapcache pages] Link: http://lkml.kernel.org/r/20190324155441.GF10344@bombadil.infradead.org [kirill@shutemov.name: hugetlb stores pages in page cache differently] Link: http://lkml.kernel.org/r/20190404134553.vuvhgmghlkiw2hgl@kshutemo-mobl1 Link: http://lkml.kernel.org/r/20190307153051.18815-1-willy@infradead.org Signed-off-by: Matthew Wilcox Acked-by: Jan Kara Reviewed-by: Kirill Shutemov Reviewed-and-tested-by: Song Liu Tested-by: William Kucharski Reviewed-by: William Kucharski Tested-by: Qian Cai Cc: Hugh Dickins Cc: Song Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pagemap.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index bcf909d0de5f..2e8438a1216a 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -333,6 +333,19 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping, mapping_gfp_mask(mapping)); } +static inline struct page *find_subpage(struct page *page, pgoff_t offset) +{ + unsigned long mask; + + if (PageHuge(page)) + return page; + + VM_BUG_ON_PAGE(PageTail(page), page); + + mask = (1UL << compound_order(page)) - 1; + return page + (offset & mask); +} + struct page *find_get_entry(struct address_space *mapping, pgoff_t offset); struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset); unsigned find_get_entries(struct address_space *mapping, pgoff_t start, -- cgit v1.2.3-59-g8ed1b