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From: Jens Axboe <axboe@kernel.dk>
To: io-uring@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 03/12] mm: abstract out wake_page_match() from wake_page_function()
Date: Sat, 23 May 2020 12:57:46 -0600
Message-ID: <20200523185755.8494-4-axboe@kernel.dk> (raw)
In-Reply-To: <20200523185755.8494-1-axboe@kernel.dk>

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

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 include/linux/pagemap.h | 37 +++++++++++++++++++++++++++++++++++++
 mm/filemap.c            | 35 ++++-------------------------------
 2 files changed, 41 insertions(+), 31 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a8f7bd8ea1c6..53d980f2208d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -456,6 +456,43 @@ 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,
diff --git a/mm/filemap.c b/mm/filemap.c
index 80747f1377d5..e891b5bee8fd 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -990,43 +990,16 @@ 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);
 }
 
-- 
2.26.2


  parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-23 18:57 [PATCHSET v2 0/12] Add support for async buffered reads Jens Axboe
2020-05-23 18:57 ` [PATCH 01/12] block: read-ahead submission should imply no-wait as well Jens Axboe
2020-05-23 18:57 ` [PATCH 02/12] mm: allow read-ahead with IOCB_NOWAIT set Jens Axboe
2020-05-23 18:57 ` Jens Axboe [this message]
2020-05-23 18:57 ` [PATCH 04/12] mm: add support for async page locking Jens Axboe
2020-05-23 18:57 ` [PATCH 05/12] mm: support async buffered reads in generic_file_buffered_read() Jens Axboe
2020-05-24 14:05   ` Trond Myklebust
2020-05-24 16:30     ` Jens Axboe
2020-05-24 16:40       ` Jens Axboe
2020-05-24 17:11         ` Trond Myklebust
2020-05-24 17:12           ` Jens Axboe
2020-05-23 18:57 ` [PATCH 06/12] fs: add FMODE_BUF_RASYNC Jens Axboe
2020-05-23 18:57 ` [PATCH 07/12] ext4: flag as supporting buffered async reads Jens Axboe
2020-05-23 18:57 ` [PATCH 08/12] block: flag block devices as supporting IOCB_WAITQ Jens Axboe
2020-05-23 18:57 ` [PATCH 09/12] xfs: flag files as supporting buffered async reads Jens Axboe
2020-05-23 18:57 ` [PATCH 10/12] btrfs: " Jens Axboe
2020-05-23 18:57 ` [PATCH 11/12] mm: add kiocb_wait_page_queue_init() helper Jens Axboe
2020-05-23 18:57 ` [PATCH 12/12] io_uring: support true async buffered reads, if file provides it Jens Axboe
2020-05-25  7:29   ` Pavel Begunkov
2020-05-25 19:59     ` Jens Axboe
2020-05-26  7:44       ` Pavel Begunkov
2020-05-26 13:50         ` Jens Axboe
2020-05-26  7:38   ` Pavel Begunkov
2020-05-26 13:47     ` Jens Axboe
2020-05-23 19:20 ` [PATCHSET v2 0/12] Add support for async buffered reads Jens Axboe
2020-05-24  9:46   ` Chris Panayis
2020-05-24 19:24     ` Jens Axboe
2020-05-24 19:21 [PATCHSET v4 " Jens Axboe
2020-05-24 19:21 ` [PATCH 03/12] mm: abstract out wake_page_match() from wake_page_function() Jens Axboe
2020-05-26 19:51 [PATCHSET v5 0/12] Add support for async buffered reads Jens Axboe
2020-05-26 19:51 ` [PATCH 03/12] mm: abstract out wake_page_match() from wake_page_function() Jens Axboe
2020-05-26 21:02   ` Johannes Weiner
2020-06-01 14:16   ` Matthew Wilcox

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