Convert mapping_get_entry() to return a folio and convert pagecache_get_page() to use the folio where possible. The seemingly dangerous cast of a page pointer to a folio pointer is safe because __page_cache_alloc() allocates an order-0 page, which is a folio by definition.
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]> --- mm/filemap.c | 45 ++++++++++++++++++++++++--------------------- 1 file changed, 24 insertions(+), 21 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index f1b65f777539..56ff6aa24265 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1673,33 +1673,33 @@ EXPORT_SYMBOL(page_cache_prev_miss); * @index: The page cache index. * * Looks up the page cache slot at @mapping & @offset. If there is a - * page cache page, the head page is returned with an increased refcount. + * page cache page, the folio 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 head page or shadow entry, %NULL if nothing is found. + * Return: The folio or shadow entry, %NULL if nothing is found. */ -static struct page *mapping_get_entry(struct address_space *mapping, +static struct folio *mapping_get_entry(struct address_space *mapping, pgoff_t index) { XA_STATE(xas, &mapping->i_pages, index); - struct page *page; + struct folio *folio; rcu_read_lock(); repeat: xas_reset(&xas); - page = xas_load(&xas); - if (xas_retry(&xas, page)) + folio = xas_load(&xas); + if (xas_retry(&xas, folio)) goto repeat; /* * A shadow entry of a recently evicted page, or a swap entry from * shmem/tmpfs. Return it without attempting to raise page count. */ - if (!page || xa_is_value(page)) + if (!folio || xa_is_value(folio)) goto out; - if (!page_cache_get_speculative(page)) + if (!page_cache_get_speculative(&folio->page)) goto repeat; /* @@ -1707,14 +1707,14 @@ static struct page *mapping_get_entry(struct address_space *mapping, * This is part of the lockless pagecache protocol. See * include/linux/pagemap.h for details. */ - if (unlikely(page != xas_reload(&xas))) { - put_page(page); + if (unlikely(folio != xas_reload(&xas))) { + put_folio(folio); goto repeat; } out: rcu_read_unlock(); - return page; + return folio; } /** @@ -1754,11 +1754,13 @@ static struct page *mapping_get_entry(struct address_space *mapping, struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, int fgp_flags, gfp_t gfp_mask) { + struct folio *folio; struct page *page; repeat: - page = mapping_get_entry(mapping, index); - if (xa_is_value(page)) { + folio = mapping_get_entry(mapping, index); + page = &folio->page; + if (xa_is_value(folio)) { if (fgp_flags & FGP_ENTRY) return page; page = NULL; @@ -1768,18 +1770,18 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, if (fgp_flags & FGP_LOCK) { if (fgp_flags & FGP_NOWAIT) { - if (!trylock_page(page)) { - put_page(page); + if (!trylock_folio(folio)) { + put_folio(folio); return NULL; } } else { - lock_page(page); + lock_folio(folio); } /* Has the page been truncated? */ if (unlikely(page->mapping != mapping)) { - unlock_page(page); - put_page(page); + unlock_folio(folio); + put_folio(folio); goto repeat; } VM_BUG_ON_PAGE(!thp_contains(page, index), page); @@ -1806,17 +1808,18 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, page = __page_cache_alloc(gfp_mask); if (!page) return NULL; + folio = (struct folio *)page; if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP)))) fgp_flags |= FGP_LOCK; /* Init accessed so avoid atomic mark_page_accessed later */ if (fgp_flags & FGP_ACCESSED) - __SetPageReferenced(page); + __SetFolioReferenced(folio); err = add_to_page_cache_lru(page, mapping, index, gfp_mask); if (unlikely(err)) { - put_page(page); + put_folio(folio); page = NULL; if (err == -EEXIST) goto repeat; @@ -1827,7 +1830,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, * an unlocked page. */ if (page && (fgp_flags & FGP_FOR_MMAP)) - unlock_page(page); + unlock_folio(folio); } return page; -- 2.29.2
