Commit c7510ab2 authored by Jens Axboe's avatar Jens Axboe
Browse files

mm: abstract out wake_page_match() from wake_page_function() 



No functional changes in this patch, just in preparation for allowing
more callers.

Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2e85abf0

include/linux/pagemap.h

+37 −0
Original line number Diff line number Diff line
@@ -496,6 +496,43 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma, 
	return pgoff;

}



/* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */

struct wait_page_key {

	struct page *page;

	int bit_nr;

	int page_match;

};



struct wait_page_queue {

	struct page *page;

	int bit_nr;

	wait_queue_entry_t wait;

};



static inline int wake_page_match(struct wait_page_queue *wait_page,

				  struct wait_page_key *key)

{

	if (wait_page->page != key->page)

	       return 0;

	key->page_match = 1;



	if (wait_page->bit_nr != key->bit_nr)

		return 0;



	/*

	 * Stop walking if it's locked.

	 * Is this safe if put_and_wait_on_page_locked() is in use?

	 * Yes: the waker must hold a reference to this page, and if PG_locked

	 * has now already been set by another task, that task must also hold

	 * a reference to the *same usage* of this page; so there is no need

	 * to walk on to wake even the put_and_wait_on_page_locked() callers.

	 */

	if (test_bit(key->bit_nr, &key->page->flags))

		return -1;



	return 1;

}



extern void __lock_page(struct page *page);

extern int __lock_page_killable(struct page *page);

extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,

mm/filemap.c

+4 −31
Original line number Diff line number Diff line
@@ -987,43 +987,16 @@ void __init pagecache_init(void) 
	page_writeback_init();

}



/* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */

struct wait_page_key {

	struct page *page;

	int bit_nr;

	int page_match;

};



struct wait_page_queue {

	struct page *page;

	int bit_nr;

	wait_queue_entry_t wait;

};



static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)

{

	struct wait_page_key *key = arg;

	struct wait_page_queue *wait_page

		= container_of(wait, struct wait_page_queue, wait);

	int ret;



	if (wait_page->page != key->page)

	       return 0;

	key->page_match = 1;



	if (wait_page->bit_nr != key->bit_nr)

		return 0;



	/*

	 * Stop walking if it's locked.

	 * Is this safe if put_and_wait_on_page_locked() is in use?

	 * Yes: the waker must hold a reference to this page, and if PG_locked

	 * has now already been set by another task, that task must also hold

	 * a reference to the *same usage* of this page; so there is no need

	 * to walk on to wake even the put_and_wait_on_page_locked() callers.

	 */

	if (test_bit(key->bit_nr, &key->page->flags))

		return -1;



	ret = wake_page_match(wait_page, key);

	if (ret != 1)

		return ret;

	return autoremove_wake_function(wait, mode, sync, key);

}