Commit bca65eea authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/filemap: Convert mapping_get_entry to return a folio 



The pagecache only contains folios, so indicate that this is definitely
not a tail page.  Shrinks mapping_get_entry() by 56 bytes, but grows
pagecache_get_page() by 21 bytes as gcc makes slightly different hot/cold
code decisions.  A net reduction of 35 bytes of text.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent 9dd3d069

mm/filemap.c

+14 −21
Original line number Diff line number Diff line
@@ -1810,49 +1810,42 @@ EXPORT_SYMBOL(page_cache_prev_miss); 
 * @mapping: the address_space to search

 * @index: The page cache index.

 *

 * Looks up the page cache slot at @mapping & @index.  If there is a

 * page cache page, the head page is returned with an increased refcount.

 * Looks up the page cache entry at @mapping & @index.  If it is a folio,

 * it is returned with an increased refcount.  If it is a shadow entry

 * of a previously evicted folio, or a swap entry from shmem/tmpfs,

 * it is returned without further action.

 *

 * 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, swap or shadow entry, %NULL if nothing is found.

 */

static struct page *mapping_get_entry(struct address_space *mapping,

		pgoff_t index)

static void *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 (!folio_try_get_rcu(folio))

		goto repeat;



	/*

	 * Has the page moved or been split?

	 * 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))) {

		folio_put(folio);

		goto repeat;

	}

out:

	rcu_read_unlock();



	return page;

	return folio;

}



/**