From: Yunlei He <heyunlei@huawei.com>
Date: Tue, 23 Feb 2016 04:07:56 +0000 (+0800)
Subject: f2fs: avoid hungtask problem caused by losing wake_up
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=0ff21646f2a5c6ff77acc51eb3df4235af39be46;p=deliverable%2Flinux.git

f2fs: avoid hungtask problem caused by losing wake_up

The D state of wait_on_all_pages_writeback should be waken by
function f2fs_write_end_io when all writeback pages have been
succesfully written to device. It's possible that wake_up comes
between get_pages and io_schedule. Maybe in this case it will
lost wake_up and still in D state even if all pages have been
write back to device, and finally, the whole system will be into
the hungtask state.

                if (!get_pages(sbi, F2FS_WRITEBACK))
                         break;
					<---------  wake_up
                io_schedule();

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Biao He <hebiao6@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 2bac8a165488..f55355d7d6b1 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -920,7 +920,7 @@ static void wait_on_all_pages_writeback(struct f2fs_sb_info *sbi)
 		if (!get_pages(sbi, F2FS_WRITEBACK))
 			break;
 
-		io_schedule();
+		io_schedule_timeout(5*HZ);
 	}
 	finish_wait(&sbi->cp_wait, &wait);
 }