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From: Artem Bityutskiy <dedekind1@gmail.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC][PATCH 09/16] writeback: do not lose wake-ups in bdi threads
Date: Fri, 16 Jul 2010 15:45:05 +0300	[thread overview]
Message-ID: <1279284312-2411-10-git-send-email-dedekind1@gmail.com> (raw)
In-Reply-To: <1279284312-2411-1-git-send-email-dedekind1@gmail.com>

From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

The bdi threads ('bdi_writeback_thread()') can lose wake-ups if,
for example, 'bdi_queue_work()' is executed while after the bdi
thread finished 'wb_do_writeback()' but before it has called
'schedule_timeout_interruptible()'.

To fix this issue, we have to check whether we have works to
process after we change the task state to 'TASK_INTERRUPTIBLE'.

Also, 'bdi_writeback_thread()' inconsistently handles the cases
when 'dirty_writeback_interval' is zero and non-zero. But there is
no fundamental difference between these cases, so they have to be
handled the same way, which this patch also does.

This patch also removes strange 'list_empty_careful()' call.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
---
 fs/fs-writeback.c |   17 +++++++++--------
 1 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 3fc5194..f045450 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -848,17 +848,18 @@ int bdi_writeback_thread(void *data)
 				break;
 		}
 
-		if (dirty_writeback_interval) {
-			wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
-			schedule_timeout_interruptible(wait_jiffies);
-		} else {
-			set_current_state(TASK_INTERRUPTIBLE);
-			if (list_empty_careful(&wb->bdi->work_list) &&
-			    !kthread_should_stop())
-				schedule();
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (!list_empty(&bdi->work_list)) {
 			__set_current_state(TASK_RUNNING);
+			continue;
 		}
 
+		if (dirty_writeback_interval) {
+			wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
+			schedule_timeout(wait_jiffies);
+		} else
+			schedule();
+
 		try_to_freeze();
 	}
 
-- 
1.7.1.1

  parent reply	other threads:[~2010-07-16 12:45 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-16 12:44 [RFC][PATCH 00/16] kill unnecessary bdi wakeups + cleanups Artem Bityutskiy
2010-07-16 12:44 ` [RFC][PATCH 01/16] writeback: do not self-wakeup Artem Bityutskiy
2010-07-18  6:44   ` Christoph Hellwig
2010-07-18  9:43     ` Artem Bityutskiy
2010-07-16 12:44 ` [RFC][PATCH 02/16] writeback: remove redundant list initialization Artem Bityutskiy
2010-07-18  6:44   ` Christoph Hellwig
2010-07-16 12:44 ` [RFC][PATCH 03/16] writeback: harmonize writeback threads naming Artem Bityutskiy
2010-07-18  6:45   ` Christoph Hellwig
2010-07-16 12:45 ` [RFC][PATCH 04/16] writeback: fix possible race when shutting down bdi Artem Bityutskiy
2010-07-18  6:47   ` Christoph Hellwig
2010-07-20  8:58     ` Artem Bityutskiy
2010-07-16 12:45 ` [RFC][PATCH 05/16] writeback: fix possible race when creating bdi threads Artem Bityutskiy
2010-07-16 12:45 ` [RFC][PATCH 06/16] writeback: improve bdi_has_dirty_io Artem Bityutskiy
2010-07-18  6:49   ` Christoph Hellwig
2010-07-16 12:45 ` [RFC][PATCH 07/16] writeback: do not lose wake-ups in the forker thread Artem Bityutskiy
2010-07-18  6:49   ` Christoph Hellwig
2010-07-16 12:45 ` [RFC][PATCH 08/16] writeback: do not lose default bdi wake-ups Artem Bityutskiy
2010-07-18  6:52   ` Christoph Hellwig
2010-07-16 12:45 ` Artem Bityutskiy [this message]
2010-07-18  6:52   ` [RFC][PATCH 09/16] writeback: do not lose wake-ups in bdi threads Christoph Hellwig
2010-07-16 12:45 ` [RFC][PATCH 10/16] writeback: simplify bdi code a little Artem Bityutskiy
2010-07-18  6:56   ` Christoph Hellwig
2010-07-20 10:34     ` Artem Bityutskiy
2010-07-16 12:45 ` [RFC][PATCH 11/16] writeback: move last_active to bdi Artem Bityutskiy
2010-07-18  7:03   ` Christoph Hellwig
2010-07-16 12:45 ` [RFC][PATCH 12/16] writeback: add to bdi_list in the forker thread Artem Bityutskiy
2010-07-18  6:58   ` Christoph Hellwig
2010-07-20 11:07     ` Artem Bityutskiy
2010-07-20 11:32     ` Artem Bityutskiy
2010-07-16 12:45 ` [RFC][PATCH 13/16] writeback: restructure bdi forker loop a little Artem Bityutskiy
2010-07-16 12:45 ` [RFC][PATCH 14/16] writeback: move bdi threads exiting logic to the forker thread Artem Bityutskiy
2010-07-18  7:02   ` Christoph Hellwig
2010-07-20 12:23     ` Artem Bityutskiy
2010-07-20 12:54     ` Artem Bityutskiy
2010-07-16 12:45 ` [RFC][PATCH 15/16] writeback: clean-up the warning about non-registered bdi Artem Bityutskiy
2010-07-18  7:03   ` Christoph Hellwig
2010-07-16 12:45 ` [RFC][PATCH 16/16] writeback: prevent unnecessary bdi threads wakeups Artem Bityutskiy
2010-07-18  7:45   ` Christoph Hellwig
2010-07-20 13:13     ` Artem Bityutskiy

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