linux-kernel - [PATCH 2/6] writeback: wb_start_writeback() should use WB_SYNC_ALL for WB_REASON

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Date:	Tue, 22 Mar 2016 11:55:16 -0600
From:	Jens Axboe <axboe@...com>
To:	<linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
	<linux-block@...r.kernel.org>
CC:	Jens Axboe <axboe@...com>
Subject: [PATCH 2/6] writeback: wb_start_writeback() should use WB_SYNC_ALL for WB_REASON_SYNC

If you call sync, the initial call to wakeup_flusher_threads() ends up
calling wb_start_writeback() with reason=WB_REASON_SYNC, but
wb_start_writeback() always uses WB_SYNC_NONE as the writeback mode.
Ensure that we use WB_SYNC_ALL for a sync operation.

Signed-off-by: Jens Axboe <axboe@...com>
---
 fs/fs-writeback.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 5c46ed9f3e14..97a9e9987134 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -936,7 +936,10 @@ void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
 		return;
 	}
 
-	work->sync_mode	= WB_SYNC_NONE;
+	if (reason == WB_REASON_SYNC)
+		work->sync_mode	= WB_SYNC_ALL;
+	else
+		work->sync_mode	= WB_SYNC_NONE;
 	work->nr_pages	= nr_pages;
 	work->range_cyclic = range_cyclic;
 	work->reason	= reason;
-- 
2.4.1.168.g1ea28e1