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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: akpm@linux-foundation.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Jeff Layton <jlayton@kernel.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	William Kucharski <william.kucharski@oracle.com>,
	David Howells <dhowells@redhat.com>
Subject: [PATCH v13 18/32] mm/filemap: Add folio_lock()
Date: Mon, 12 Jul 2021 20:01:50 +0100	[thread overview]
Message-ID: <20210712190204.80979-19-willy@infradead.org> (raw)
In-Reply-To: <20210712190204.80979-1-willy@infradead.org>

This is like lock_page() but for use by callers who know they have a folio.
Convert __lock_page() to be __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: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
---
 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 096c8154dffb..5c82933af2fe 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -653,7 +653,7 @@ 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,
@@ -661,13 +661,24 @@ 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);
 }
 
 /*
@@ -675,9 +686,12 @@ 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);
 }
 
 /*
diff --git a/mm/filemap.c b/mm/filemap.c
index 1f41d0911d8f..cc2682b72584 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.
+			 * __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.
@@ -1578,17 +1578,16 @@ 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)
 {
@@ -1663,10 +1662,10 @@ 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;
 }
 
 /**
@@ -2837,7 +2836,9 @@ 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;
 
 	/*
@@ -2850,7 +2851,7 @@ 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
@@ -2862,11 +2863,11 @@ 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
-- 
2.30.2


  parent reply	other threads:[~2021-07-12 19:12 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-12 19:01 [PATCH v13a 00/32] Memory folios Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 01/32] mm: Convert get_page_unless_zero() to return bool Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 02/32] mm: Introduce struct folio Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 03/32] mm: Add folio_pgdat(), folio_zone() and folio_zonenum() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 04/32] mm/vmstat: Add functions to account folio statistics Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 05/32] mm/debug: Add VM_BUG_ON_FOLIO() and VM_WARN_ON_ONCE_FOLIO() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 06/32] mm: Add folio reference count functions Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 07/32] mm: Add folio_put() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 08/32] mm: Add folio_get() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 09/32] mm: Add folio_try_get_rcu() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 10/32] mm: Add folio flag manipulation functions Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 11/32] mm/lru: Add folio LRU functions Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 12/32] mm: Handle per-folio private data Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 13/32] mm/filemap: Add folio_index(), folio_file_page() and folio_contains() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 14/32] mm/filemap: Add folio_next_index() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 15/32] mm/filemap: Add folio_pos() and folio_file_pos() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 16/32] mm/util: Add folio_mapping() and folio_file_mapping() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 17/32] mm/filemap: Add folio_unlock() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` Matthew Wilcox (Oracle) [this message]
2021-07-12 19:01 ` [PATCH v13 19/32] mm/filemap: Add folio_lock_killable() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 20/32] mm/filemap: Add __folio_lock_async() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 21/32] mm/filemap: Add folio_wait_locked() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 22/32] mm/filemap: Add __folio_lock_or_retry() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 23/32] mm/swap: Add folio_rotate_reclaimable() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 24/32] mm/filemap: Add folio_end_writeback() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 25/32] mm/writeback: Add folio_wait_writeback() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 26/32] mm/writeback: Add folio_wait_stable() Matthew Wilcox (Oracle)
2021-07-12 19:01 ` [PATCH v13 27/32] mm/filemap: Add folio_wait_bit() Matthew Wilcox (Oracle)
2021-07-12 19:02 ` [PATCH v13 28/32] mm/filemap: Add folio_wake_bit() Matthew Wilcox (Oracle)
2021-07-12 19:02 ` [PATCH v13 29/32] mm/filemap: Convert page wait queues to be folios Matthew Wilcox (Oracle)
2021-07-12 19:02 ` [PATCH v13 30/32] mm/filemap: Add folio private_2 functions Matthew Wilcox (Oracle)
2021-07-12 19:02 ` [PATCH v13 31/32] fs/netfs: Add folio fscache functions Matthew Wilcox (Oracle)
2021-07-12 19:02 ` [PATCH v13 32/32] mm: Add folio_mapped() Matthew Wilcox (Oracle)

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