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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, akpm@linux-foundation.org,
	Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 05/12] mm: support async buffered reads in generic_file_buffered_read()
Date: Tue, 26 May 2020 13:51:16 -0600
Message-ID: <20200526195123.29053-6-axboe@kernel.dk> (raw)
In-Reply-To: <20200526195123.29053-1-axboe@kernel.dk>

Use the async page locking infrastructure, if IOCB_WAITQ is set in the
passed in iocb. The caller must expect an -EIOCBQUEUED return value,
which means that IO is started but not done yet. This is similar to how
O_DIRECT signals the same operation. Once the callback is received by
the caller for IO completion, the caller must retry the operation.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 mm/filemap.c | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index c746541b1d49..18022de7dc33 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1219,6 +1219,14 @@ static int __wait_on_page_locked_async(struct page *page,
 	return ret;
 }
 
+static int wait_on_page_locked_async(struct page *page,
+				     struct wait_page_queue *wait)
+{
+	if (!PageLocked(page))
+		return 0;
+	return __wait_on_page_locked_async(compound_head(page), wait, false);
+}
+
 /**
  * put_and_wait_on_page_locked - Drop a reference and wait for it to be unlocked
  * @page: The page to wait for.
@@ -2058,17 +2066,25 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 					index, last_index - index);
 		}
 		if (!PageUptodate(page)) {
-			if (iocb->ki_flags & IOCB_NOWAIT) {
-				put_page(page);
-				goto would_block;
-			}
-
 			/*
 			 * See comment in do_read_cache_page on why
 			 * wait_on_page_locked is used to avoid unnecessarily
 			 * serialisations and why it's safe.
 			 */
-			error = wait_on_page_locked_killable(page);
+			if (iocb->ki_flags & IOCB_WAITQ) {
+				if (written) {
+					put_page(page);
+					goto out;
+				}
+				error = wait_on_page_locked_async(page,
+								iocb->ki_waitq);
+			} else {
+				if (iocb->ki_flags & IOCB_NOWAIT) {
+					put_page(page);
+					goto would_block;
+				}
+				error = wait_on_page_locked_killable(page);
+			}
 			if (unlikely(error))
 				goto readpage_error;
 			if (PageUptodate(page))
@@ -2156,7 +2172,10 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 
 page_not_up_to_date:
 		/* Get exclusive access to the page ... */
-		error = lock_page_killable(page);
+		if (iocb->ki_flags & IOCB_WAITQ)
+			error = lock_page_async(page, iocb->ki_waitq);
+		else
+			error = lock_page_killable(page);
 		if (unlikely(error))
 			goto readpage_error;
 
-- 
2.26.2


  parent reply index

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-26 19:51 [PATCHSET v5 0/12] Add support for async buffered reads Jens Axboe
2020-05-26 19:51 ` [PATCH 01/12] block: read-ahead submission should imply no-wait as well Jens Axboe
2020-05-26 19:51 ` [PATCH 02/12] mm: allow read-ahead with IOCB_NOWAIT set Jens Axboe
2020-05-26 20:45   ` Johannes Weiner
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
2020-05-26 19:51 ` [PATCH 04/12] mm: add support for async page locking Jens Axboe
2020-05-26 21:59   ` Johannes Weiner
2020-05-26 22:01     ` Jens Axboe
2020-05-27 16:02       ` Johannes Weiner
2020-06-01 14:26   ` Matthew Wilcox
2020-06-01 17:15     ` Jens Axboe
2020-05-26 19:51 ` Jens Axboe [this message]
2020-05-26 22:00   ` [PATCH 05/12] mm: support async buffered reads in generic_file_buffered_read() Johannes Weiner
2020-05-26 19:51 ` [PATCH 06/12] fs: add FMODE_BUF_RASYNC Jens Axboe
2020-05-26 19:51 ` [PATCH 07/12] ext4: flag as supporting buffered async reads Jens Axboe
2020-05-26 19:51 ` [PATCH 08/12] block: flag block devices as supporting IOCB_WAITQ Jens Axboe
2020-05-26 19:51 ` [PATCH 09/12] xfs: flag files as supporting buffered async reads Jens Axboe
2020-05-28 17:53   ` Darrick J. Wong
2020-05-28 19:23     ` Jens Axboe
2020-05-26 19:51 ` [PATCH 10/12] btrfs: " Jens Axboe
2020-05-26 19:57   ` Chris Mason
2020-05-26 19:51 ` [PATCH 11/12] mm: add kiocb_wait_page_queue_init() helper Jens Axboe
2020-05-26 22:01   ` Johannes Weiner
2020-05-26 19:51 ` [PATCH 12/12] io_uring: support true async buffered reads, if file provides it Jens Axboe
     [not found] ` <CA+icZUWfX+QmroE6j74C7o-BdfMF5=6PdYrA=5W_JCKddqkJgQ@mail.gmail.com>
2020-05-28 17:06   ` [PATCHSET v5 0/12] Add support for async buffered reads Jens Axboe
2020-05-28 17:12     ` Sedat Dilek
2020-05-28 17:14       ` Jens Axboe
2020-05-28 18:20         ` Sedat Dilek
2020-05-29 10:02     ` Sedat Dilek
2020-05-29 11:22       ` Sedat Dilek
2020-05-30 13:36         ` Sedat Dilek
2020-05-30 18:57           ` Sedat Dilek
2020-05-31  1:57             ` Jens Axboe
     [not found]               ` <CA+icZUXxmOA-5+dukCgxfSp4eVHB+QaAHO6tsgq0iioQs3Af-w@mail.gmail.com>
2020-05-31  7:12                 ` Sedat Dilek
2020-06-01 13:35                   ` Sedat Dilek
2020-06-01 14:04                     ` Jens Axboe
2020-06-01 14:13                       ` Sedat Dilek
2020-06-01 14:14                         ` Jens Axboe
2020-06-01 14:35                           ` Jens Axboe
2020-06-01 14:43                             ` Sedat Dilek
2020-06-01 14:46                               ` Jens Axboe
2020-06-01 14:51                                 ` Sedat Dilek
2020-06-01 20:18                                 ` Sedat Dilek
     [not found] ` <20200604005916.niy2mejjcsx4sv6t@alap3.anarazel.de>
2020-06-04  1:04   ` Jens Axboe
2020-06-04  1:30     ` Andres Freund
2020-06-05 19:56       ` Andres Freund
2020-06-05 14:42     ` Jens Axboe
2020-06-05 20:20       ` Andres Freund
2020-06-05 20:21         ` Jens Axboe
2020-06-05 20:36         ` Andres Freund
2020-06-05 20:53           ` Jens Axboe
2020-06-05 21:13             ` Jens Axboe
2020-06-05 21:21               ` Jens Axboe
2020-06-05 22:30                 ` Andres Freund
2020-06-05 22:36                   ` Andres Freund
2020-06-05 22:49                     ` Jens Axboe
2020-06-05 22:54                       ` Andres Freund
2020-06-05 22:56                         ` Jens Axboe
2020-06-05 23:02                           ` Andres Freund
2020-06-06  0:33                 ` Sedat Dilek
2020-06-06 16:04                   ` Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2020-05-24 19:21 [PATCHSET v4 " Jens Axboe
2020-05-24 19:21 ` [PATCH 05/12] mm: support async buffered reads in generic_file_buffered_read() Jens Axboe
2020-05-23 18:57 [PATCHSET v2 0/12] Add support for async buffered reads 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

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