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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: linux-mm@kvack.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-cachefs@redhat.com, linux-afs@lists.infradead.org,
	Christoph Hellwig <hch@lst.de>, Jeff Layton <jlayton@kernel.org>
Subject: [PATCH v7 18/28] mm/filemap: Add lock_folio
Date: Fri,  9 Apr 2021 19:50:55 +0100	[thread overview]
Message-ID: <20210409185105.188284-19-willy@infradead.org> (raw)
In-Reply-To: <20210409185105.188284-1-willy@infradead.org>

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

Saves 362 bytes of text; mostly from improved register allocation and
inlining decisions.  __lock_folio is 59 bytes while __lock_page was 79.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
---
 include/linux/pagemap.h | 24 +++++++++++++++++++-----
 mm/filemap.c            | 29 +++++++++++++++--------------
 2 files changed, 34 insertions(+), 19 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index d94c9f8a451d..c59b19f1cb0f 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -714,7 +714,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,
 	return true;
 }
 
-extern void __lock_page(struct page *page);
+void __lock_folio(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,
@@ -722,13 +722,24 @@ extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 void unlock_page(struct page *page);
 void unlock_folio(struct folio *folio);
 
+static inline bool trylock_folio(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 trylock_folio(page_folio(page));
+}
+
+static inline void lock_folio(struct folio *folio)
+{
+	might_sleep();
+	if (!trylock_folio(folio))
+		__lock_folio(folio);
 }
 
 /*
@@ -736,9 +747,12 @@ 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 (!trylock_folio(folio))
+		__lock_folio(folio);
 }
 
 /*
diff --git a/mm/filemap.c b/mm/filemap.c
index d1cf51274921..36289a9816b5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1187,7 +1187,7 @@ 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.
+			 * __lock_folio() 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.
@@ -1574,17 +1574,16 @@ 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
+ * __lock_folio - 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 __lock_folio(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(__lock_folio);
 
 int __lock_page_killable(struct page *__page)
 {
@@ -1659,10 +1658,10 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 			return 0;
 		}
 	} else {
-		__lock_page(page);
+		__lock_folio(page_folio(page));
 	}
-	return 1;
 
+	return 1;
 }
 
 /**
@@ -2806,7 +2805,9 @@ 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 (trylock_folio(folio))
 		return 1;
 
 	/*
@@ -2819,7 +2820,7 @@ 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
@@ -2831,11 +2832,11 @@ static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
 			return 0;
 		}
 	} else
-		__lock_page(page);
+		__lock_folio(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
-- 
2.30.2


  parent reply	other threads:[~2021-04-09 19:06 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-09 18:50 [PATCH v7 00/28] Memory Folios Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 01/28] mm: Optimise nth_page for contiguous memmap Matthew Wilcox (Oracle)
2021-04-12  6:08   ` Christoph Hellwig
2021-04-09 18:50 ` [PATCH v7 02/28] mm: Introduce struct folio Matthew Wilcox (Oracle)
2021-04-09 22:45   ` kernel test robot
2021-04-10  2:43     ` Bogus struct page layout on 32-bit Matthew Wilcox
2021-04-10  6:21       ` Jesper Dangaard Brouer
2021-04-10  8:52         ` Ilias Apalodimas
2021-04-10 14:06           ` Matthew Wilcox
2021-04-10 15:54             ` Russell King - ARM Linux admin
2021-04-16  9:26           ` Grygorii Strashko
2021-04-16 14:10             ` Arnd Bergmann
2021-04-17 13:08             ` David Laight
2021-04-10 14:17       ` David Laight
2021-04-10 19:10       ` Arnd Bergmann
2021-04-11 22:35         ` Matthew Wilcox
2021-04-10  2:51   ` [PATCH v7 02/28] mm: Introduce struct folio kernel test robot
2021-04-16 15:55   ` Matthew Wilcox
2021-04-19  9:06     ` Kirill A. Shutemov
2021-04-09 18:50 ` [PATCH v7 03/28] mm: Add folio_pgdat and folio_zone Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 04/28] mm/vmstat: Add functions to account folio statistics Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 05/28] mm/debug: Add VM_BUG_ON_FOLIO and VM_WARN_ON_ONCE_FOLIO Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 06/28] mm: Add folio reference count functions Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 07/28] mm: Add put_folio Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 08/28] mm: Add get_folio Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 09/28] mm: Create FolioFlags Matthew Wilcox (Oracle)
2021-04-19 13:25   ` Peter Zijlstra
2021-04-19 13:55     ` Matthew Wilcox
2021-04-09 18:50 ` [PATCH v7 10/28] mm: Handle per-folio private data Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 11/28] mm/filemap: Add folio_index, folio_file_page and folio_contains Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 12/28] mm/filemap: Add folio_next_index Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 13/28] mm/filemap: Add folio_offset and folio_file_offset Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 14/28] mm/util: Add folio_mapping and folio_file_mapping Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 15/28] mm: Add folio_mapcount Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 16/28] mm/memcg: Add folio wrappers for various functions Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 17/28] mm/filemap: Add unlock_folio Matthew Wilcox (Oracle)
2021-04-09 18:50 ` Matthew Wilcox (Oracle) [this message]
2021-04-09 18:50 ` [PATCH v7 19/28] mm/filemap: Add lock_folio_killable Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 20/28] mm/filemap: Add __lock_folio_async Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 21/28] mm/filemap: Add __lock_folio_or_retry Matthew Wilcox (Oracle)
2021-04-09 18:50 ` [PATCH v7 22/28] mm/filemap: Add wait_on_folio_locked Matthew Wilcox (Oracle)
2021-04-09 18:51 ` [PATCH v7 23/28] mm/filemap: Add end_folio_writeback Matthew Wilcox (Oracle)
2021-04-09 18:51 ` [PATCH v7 24/28] mm/writeback: Add wait_on_folio_writeback Matthew Wilcox (Oracle)
2021-04-09 18:51 ` [PATCH v7 25/28] mm/writeback: Add wait_for_stable_folio Matthew Wilcox (Oracle)
2021-04-09 18:51 ` [PATCH v7 26/28] mm/filemap: Convert wait_on_page_bit to wait_on_folio_bit Matthew Wilcox (Oracle)
2021-04-09 18:51 ` [PATCH v7 27/28] mm/filemap: Convert wake_up_page_bit to wake_up_folio_bit Matthew Wilcox (Oracle)
2021-04-09 18:51 ` [PATCH v7 28/28] mm/filemap: Convert page wait queues to be folios Matthew Wilcox (Oracle)

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