Commit 4c7472c0 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

page cache: Convert find_get_entry to XArray 



Slightly shorter and simpler code.

Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
parent 5c024e6a

mm/filemap.c

+28 −35
Original line number Original line Diff line number Diff line
@@ -1382,27 +1382,21 @@ EXPORT_SYMBOL(page_cache_prev_miss); 
 */

 */

struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)

struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)

{

{

	void **pagep;

	XA_STATE(xas, &mapping->i_pages, offset);

	struct page *head, *page;

	struct page *head, *page;





	rcu_read_lock();

	rcu_read_lock();

repeat:

repeat:

	page = NULL;

	xas_reset(&xas);

	pagep = radix_tree_lookup_slot(&mapping->i_pages, offset);

	page = xas_load(&xas);

	if (pagep) {

	if (xas_retry(&xas, page))

		page = radix_tree_deref_slot(pagep);

		if (unlikely(!page))

			goto out;

		if (radix_tree_exception(page)) {

			if (radix_tree_deref_retry(page))

		goto repeat;

		goto repeat;

	/*

	/*

			 * A shadow entry of a recently evicted page,

	 * A shadow entry of a recently evicted page, or a swap entry from

			 * or a swap entry from shmem/tmpfs.  Return

	 * shmem/tmpfs.  Return it without attempting to raise page count.

			 * it without attempting to raise page count.

	 */

	 */

	if (!page || xa_is_value(page))

		goto out;

		goto out;

		}





	head = compound_head(page);

	head = compound_head(page);

	if (!page_cache_get_speculative(head))

	if (!page_cache_get_speculative(head))
@@ -1419,11 +1413,10 @@ struct page *find_get_entry(struct address_space *mapping, pgoff_t offset) 
	 * This is part of the lockless pagecache protocol. See

	 * This is part of the lockless pagecache protocol. See

	 * include/linux/pagemap.h for details.

	 * include/linux/pagemap.h for details.

	 */

	 */

		if (unlikely(page != *pagep)) {

	if (unlikely(page != xas_reload(&xas))) {

		put_page(head);

		put_page(head);

		goto repeat;

		goto repeat;

	}

	}

	}

out:

out:

	rcu_read_unlock();

	rcu_read_unlock();
@@ -1453,7 +1446,7 @@ struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset) 




repeat:

repeat:

	page = find_get_entry(mapping, offset);

	page = find_get_entry(mapping, offset);

	if (page && !radix_tree_exception(page)) {

	if (page && !xa_is_value(page)) {

		lock_page(page);

		lock_page(page);

		/* Has the page been truncated? */

		/* Has the page been truncated? */

		if (unlikely(page_mapping(page) != mapping)) {

		if (unlikely(page_mapping(page) != mapping)) {