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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: akpm@linux-foundation.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Jeff Layton <jlayton@kernel.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	William Kucharski <william.kucharski@oracle.com>
Subject: [PATCH v11 18/33] mm/filemap: Add folio_unlock()
Date: Mon, 14 Jun 2021 21:14:20 +0100	[thread overview]
Message-ID: <20210614201435.1379188-19-willy@infradead.org> (raw)
In-Reply-To: <20210614201435.1379188-1-willy@infradead.org>

Convert unlock_page() to call folio_unlock().  By using a folio we
avoid a call to compound_head().  This shortens the function from 39
bytes to 25 and removes 4 instructions on x86-64.  Because we still
have unlock_page(), it's a net increase of 16 bytes of text for the
kernel as a whole, but any path that uses folio_unlock() will execute
4 fewer instructions.

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>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
---
 include/linux/pagemap.h |  3 ++-
 mm/filemap.c            | 29 ++++++++++++-----------------
 mm/folio-compat.c       |  6 ++++++
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 98becc81f069..9faf19f4c9f9 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -646,7 +646,8 @@ 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,
 				unsigned int flags);
-extern void unlock_page(struct page *page);
+void unlock_page(struct page *page);
+void folio_unlock(struct folio *folio);
 
 /*
  * Return true if the page was successfully locked
diff --git a/mm/filemap.c b/mm/filemap.c
index 817a47059bd0..4cbed91d456a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1435,29 +1435,24 @@ static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem
 #endif
 
 /**
- * unlock_page - unlock a locked page
- * @page: the page
+ * folio_unlock - Unlock a locked folio.
+ * @folio: The folio.
  *
- * Unlocks the page and wakes up sleepers in wait_on_page_locked().
- * Also wakes sleepers in wait_on_page_writeback() because the wakeup
- * mechanism between PageLocked pages and PageWriteback pages is shared.
- * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
+ * Unlocks the folio and wakes up any thread sleeping on the page lock.
  *
- * Note that this depends on PG_waiters being the sign bit in the byte
- * that contains PG_locked - thus the BUILD_BUG_ON(). That allows us to
- * clear the PG_locked bit and test PG_waiters at the same time fairly
- * portably (architectures that do LL/SC can test any bit, while x86 can
- * test the sign bit).
+ * Context: May be called from interrupt or process context.  May not be
+ * called from NMI context.
  */
-void unlock_page(struct page *page)
+void folio_unlock(struct folio *folio)
 {
+	/* Bit 7 allows x86 to check the byte's sign bit */
 	BUILD_BUG_ON(PG_waiters != 7);
-	page = compound_head(page);
-	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags))
-		wake_up_page_bit(page, PG_locked);
+	BUILD_BUG_ON(PG_locked > 7);
+	VM_BUG_ON_FOLIO(!folio_locked(folio), folio);
+	if (clear_bit_unlock_is_negative_byte(PG_locked, folio_flags(folio, 0)))
+		wake_up_page_bit(&folio->page, PG_locked);
 }
-EXPORT_SYMBOL(unlock_page);
+EXPORT_SYMBOL(folio_unlock);
 
 /**
  * end_page_private_2 - Clear PG_private_2 and release any waiters
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index 5e107aa30a62..91b3d00a92f7 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -11,3 +11,9 @@ struct address_space *page_mapping(struct page *page)
 	return folio_mapping(page_folio(page));
 }
 EXPORT_SYMBOL(page_mapping);
+
+void unlock_page(struct page *page)
+{
+	return folio_unlock(page_folio(page));
+}
+EXPORT_SYMBOL(unlock_page);
-- 
2.30.2


  parent reply	other threads:[~2021-06-14 20:27 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14 20:14 [PATCH v11 00/33] Memory folios Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 01/33] mm: Convert get_page_unless_zero() to return bool Matthew Wilcox (Oracle)
2021-06-15  6:24   ` Christoph Hellwig
2021-06-14 20:14 ` [PATCH v11 02/33] mm: Introduce struct folio Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 03/33] mm: Add folio_pgdat(), folio_zone() and folio_zonenum() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 04/33] mm/vmstat: Add functions to account folio statistics Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 05/33] mm/debug: Add VM_BUG_ON_FOLIO() and VM_WARN_ON_ONCE_FOLIO() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 06/33] mm: Add folio reference count functions Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 07/33] mm: Add folio_put() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 08/33] mm: Add folio_get() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 09/33] mm: Add folio_try_get_rcu() Matthew Wilcox (Oracle)
2021-06-15  6:25   ` Christoph Hellwig
2021-06-14 20:14 ` [PATCH v11 10/33] mm: Add folio flag manipulation functions Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 11/33] mm/lru: Add folio LRU functions Matthew Wilcox (Oracle)
2021-06-15  6:27   ` Christoph Hellwig
2021-06-14 20:14 ` [PATCH v11 12/33] mm: Handle per-folio private data Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 13/33] mm/filemap: Add folio_index(), folio_file_page() and folio_contains() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 14/33] mm/filemap: Add folio_next_index() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 15/33] mm/filemap: Add folio_offset() and folio_file_offset() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 16/33] mm/util: Add folio_mapping() and folio_file_mapping() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 17/33] mm/memcg: Add folio wrappers for various functions Matthew Wilcox (Oracle)
2021-06-14 20:14 ` Matthew Wilcox (Oracle) [this message]
2021-06-14 20:14 ` [PATCH v11 19/33] mm/filemap: Add folio_lock() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 20/33] mm/filemap: Add folio_lock_killable() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 21/33] mm/filemap: Add __folio_lock_async() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 22/33] mm/filemap: Add folio_wait_locked() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 23/33] mm/filemap: Add __folio_lock_or_retry() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 24/33] mm/swap: Add folio_rotate_reclaimable() Matthew Wilcox (Oracle)
2021-06-15  6:29   ` Christoph Hellwig
2021-06-14 20:14 ` [PATCH v11 25/33] mm/filemap: Add folio_end_writeback() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 26/33] mm/writeback: Add folio_wait_writeback() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 27/33] mm/writeback: Add folio_wait_stable() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 28/33] mm/filemap: Add folio_wait_bit() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 29/33] mm/filemap: Add folio_wake_bit() Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 30/33] mm/filemap: Convert page wait queues to be folios Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 31/33] mm/filemap: Add folio private_2 functions Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 32/33] fs/netfs: Add folio fscache functions Matthew Wilcox (Oracle)
2021-06-14 20:14 ` [PATCH v11 33/33] mm: Add folio_mapped() Matthew Wilcox (Oracle)
2021-06-15  6:31   ` Christoph Hellwig
2021-06-16  9:16 ` [PATCH v11 32/33] fs/netfs: Add folio fscache functions David Howells
2021-06-16  9:19 ` [PATCH v11 01/33] mm: Convert get_page_unless_zero() to return bool David Howells
2021-06-16  9:31 ` [PATCH v11 02/33] mm: Introduce struct folio David Howells
2021-06-16  9:36 ` [PATCH v11 04/33] mm/vmstat: Add functions to account folio statistics David Howells
2021-06-16  9:54 ` [PATCH v11 05/33] mm/debug: Add VM_BUG_ON_FOLIO() and VM_WARN_ON_ONCE_FOLIO() David Howells
2021-06-16  9:55 ` [PATCH v11 06/33] mm: Add folio reference count functions David Howells
2021-06-16  9:55 ` [PATCH v11 07/33] mm: Add folio_put() David Howells
2021-06-16  9:56 ` [PATCH v11 08/33] mm: Add folio_get() David Howells
2021-06-16  9:58 ` [PATCH v11 10/33] mm: Add folio flag manipulation functions David Howells
2021-06-16 10:00 ` [PATCH v11 11/33] mm/lru: Add folio LRU functions David Howells
2021-06-16 10:03 ` [PATCH v11 13/33] mm/filemap: Add folio_index(), folio_file_page() and folio_contains() David Howells
2021-06-16 11:38   ` Matthew Wilcox
2021-06-16 10:04 ` [PATCH v11 14/33] mm/filemap: Add folio_next_index() David Howells
2021-06-16 10:05 ` [PATCH v11 15/33] mm/filemap: Add folio_offset() and folio_file_offset() David Howells
2021-06-16 10:10 ` [PATCH v11 16/33] mm/util: Add folio_mapping() and folio_file_mapping() David Howells
2021-06-16 10:13 ` [PATCH v11 18/33] mm/filemap: Add folio_unlock() David Howells
2021-06-16 10:17 ` [PATCH v11 19/33] mm/filemap: Add folio_lock() David Howells
2021-06-16 10:22 ` [PATCH v11 21/33] mm/filemap: Add __folio_lock_async() David Howells
2021-06-16 10:23 ` [PATCH v11 22/33] mm/filemap: Add folio_wait_locked() David Howells
2021-06-16 10:27 ` [PATCH v11 24/33] mm/swap: Add folio_rotate_reclaimable() David Howells
2021-06-16 11:46   ` Matthew Wilcox
2021-06-16 10:30 ` [PATCH v11 26/33] mm/writeback: Add folio_wait_writeback() David Howells
2021-06-16 11:55   ` Matthew Wilcox
2021-06-16 10:32 ` [PATCH v11 27/33] mm/writeback: Add folio_wait_stable() David Howells
2021-06-16 10:33 ` [PATCH v11 28/33] mm/filemap: Add folio_wait_bit() David Howells
2021-06-16 10:35 ` [PATCH v11 30/33] mm/filemap: Convert page wait queues to be folios David Howells
2021-06-16 10:37 ` [PATCH v11 33/33] mm: Add folio_mapped() David Howells
2021-06-16 10:41 ` [PATCH v11 02/33] mm: Introduce struct folio David Howells
2021-06-16 10:54 ` [PATCH v11 00/33] Memory folios David Howells

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