Commit 7c23c782 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/filemap: Add folio_lock() 



This is like lock_page() but for use by callers who know they have a folio.
Convert __lock_page() to be __folio_lock().  This saves one call to
compound_head() per contended call to lock_page().

Saves 455 bytes of text; mostly from improved register allocation and
inlining decisions.  __folio_lock is 59 bytes while __lock_page was 79.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarJeff Layton <jlayton@kernel.org>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarMike Rapoport <rppt@linux.ibm.com>
parent 4e136428

include/linux/pagemap.h

+19 −5
Original line number Diff line number Diff line
@@ -652,7 +652,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page, 
	return true;

}



extern void __lock_page(struct page *page);

void __folio_lock(struct folio *folio);

extern int __lock_page_killable(struct page *page);

extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);

extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
@@ -660,13 +660,24 @@ extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, 
void unlock_page(struct page *page);

void folio_unlock(struct folio *folio);



static inline bool folio_trylock(struct folio *folio)

{

	return likely(!test_and_set_bit_lock(PG_locked, folio_flags(folio, 0)));

}



/*

 * Return true if the page was successfully locked

 */

static inline int trylock_page(struct page *page)

{

	page = compound_head(page);

	return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));

	return folio_trylock(page_folio(page));

}



static inline void folio_lock(struct folio *folio)

{

	might_sleep();

	if (!folio_trylock(folio))

		__folio_lock(folio);

}



/*
@@ -674,9 +685,12 @@ static inline int trylock_page(struct page *page) 
 */

static inline void lock_page(struct page *page)

{

	struct folio *folio;

	might_sleep();

	if (!trylock_page(page))

		__lock_page(page);



	folio = page_folio(page);

	if (!folio_trylock(folio))

		__folio_lock(folio);

}



/*

mm/filemap.c

+15 −14
Original line number Diff line number Diff line
@@ -1242,7 +1242,7 @@ static void wake_up_page(struct page *page, int bit) 
 */

enum behavior {

	EXCLUSIVE,	/* Hold ref to page and take the bit when woken, like

			 * __lock_page() waiting on then setting PG_locked.

			 * __folio_lock() waiting on then setting PG_locked.

			 */

	SHARED,		/* Hold ref to page and check the bit when woken, like

			 * wait_on_page_writeback() waiting on PG_writeback.
@@ -1633,17 +1633,16 @@ void page_endio(struct page *page, bool is_write, int err) 
EXPORT_SYMBOL_GPL(page_endio);



/**

 * __lock_page - get a lock on the page, assuming we need to sleep to get it

 * @__page: the page to lock

 * __folio_lock - Get a lock on the folio, assuming we need to sleep to get it.

 * @folio: The folio to lock

 */

void __lock_page(struct page *__page)

void __folio_lock(struct folio *folio)

{

	struct page *page = compound_head(__page);

	wait_queue_head_t *q = page_waitqueue(page);

	wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE,

	wait_queue_head_t *q = page_waitqueue(&folio->page);

	wait_on_page_bit_common(q, &folio->page, PG_locked, TASK_UNINTERRUPTIBLE,

				EXCLUSIVE);

}

EXPORT_SYMBOL(__lock_page);

EXPORT_SYMBOL(__folio_lock);



int __lock_page_killable(struct page *__page)

{
@@ -1718,10 +1717,10 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm, 
			return 0;

		}

	} else {

		__lock_page(page);

		__folio_lock(page_folio(page));

	}

	return 1;



	return 1;

}



/**
@@ -2915,7 +2914,9 @@ loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start, 
static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,

				     struct file **fpin)

{

	if (trylock_page(page))

	struct folio *folio = page_folio(page);



	if (folio_trylock(folio))

		return 1;



	/*
@@ -2928,7 +2929,7 @@ static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page, 


	*fpin = maybe_unlock_mmap_for_io(vmf, *fpin);

	if (vmf->flags & FAULT_FLAG_KILLABLE) {

		if (__lock_page_killable(page)) {

		if (__lock_page_killable(&folio->page)) {

			/*

			 * We didn't have the right flags to drop the mmap_lock,

			 * but all fault_handlers only check for fatal signals
@@ -2940,11 +2941,11 @@ static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page, 
			return 0;

		}

	} else

		__lock_page(page);

		__folio_lock(folio);



	return 1;

}





/*

 * Synchronous readahead happens when we don't even find a page in the page

 * cache at all.  We don't want to perform IO under the mmap sem, so if we have