From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm: convert find_get_entry to return the head page There are only four callers remaining of find_get_entry(). get_shadow_from_swap_cache() only wants to see shadow entries and doesn't care about which page is returned. Push the find_subpage() call into find_lock_entry(), find_get_incore_page() and pagecache_get_page(). [willy@xxxxxxxxxxxxx: fix oops] Link: https://lkml.kernel.org/r/20200914112738.GM6583@xxxxxxxxxxxxxxxxxxxx Link: https://lkml.kernel.org/r/20200910183318.20139-7-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Huang Ying <ying.huang@xxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Matthew Auld <matthew.auld@xxxxxxxxx> Cc: William Kucharski <william.kucharski@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/filemap.c | 13 +++++++------ mm/swap_state.c | 4 +++- 2 files changed, 10 insertions(+), 7 deletions(-) --- a/mm/filemap.c~mm-convert-find_get_entry-to-return-the-head-page +++ a/mm/filemap.c @@ -1645,19 +1645,19 @@ EXPORT_SYMBOL(page_cache_prev_miss); /** * find_get_entry - find and get a page cache entry * @mapping: the address_space to search - * @offset: the page cache index + * @index: The page cache index. * * Looks up the page cache slot at @mapping & @offset. If there is a - * page cache page, it is returned with an increased refcount. + * page cache page, the head page is returned with an increased refcount. * * If the slot holds a shadow entry of a previously evicted page, or a * swap entry from shmem/tmpfs, it is returned. * - * Return: the found page or shadow entry, %NULL if nothing is found. + * Return: The head page or shadow entry, %NULL if nothing is found. */ -struct page *find_get_entry(struct address_space *mapping, pgoff_t offset) +struct page *find_get_entry(struct address_space *mapping, pgoff_t index) { - XA_STATE(xas, &mapping->i_pages, offset); + XA_STATE(xas, &mapping->i_pages, index); struct page *page; rcu_read_lock(); @@ -1685,7 +1685,6 @@ repeat: put_page(page); goto repeat; } - page = find_subpage(page, offset); out: rcu_read_unlock(); @@ -1722,6 +1721,7 @@ repeat: put_page(page); goto repeat; } + page = find_subpage(page, offset); VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page); } return page; @@ -1768,6 +1768,7 @@ repeat: page = NULL; if (!page) goto no_page; + page = find_subpage(page, index); if (fgp_flags & FGP_LOCK) { if (fgp_flags & FGP_NOWAIT) { --- a/mm/swap_state.c~mm-convert-find_get_entry-to-return-the-head-page +++ a/mm/swap_state.c @@ -431,8 +431,10 @@ struct page *find_get_incore_page(struct struct swap_info_struct *si; struct page *page = find_get_entry(mapping, index); - if (!xa_is_value(page)) + if (!page) return page; + if (!xa_is_value(page)) + return find_subpage(page, index); if (!shmem_mapping(mapping)) return NULL; _
