From: Shan Hai <shan.hai@oracle.com>
Date: Wed, 22 Aug 2018 18:02:56 +0000 (+0800)
Subject: bcache: release dc->writeback_lock properly in bch_writeback_thread()
X-Git-Tag: v4.4.155~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=95861df6188b3960e1d80292c905e3d040fd619c;p=thirdparty%2Fkernel%2Fstable.git

bcache: release dc->writeback_lock properly in bch_writeback_thread()

commit 3943b040f11ed0cc6d4585fd286a623ca8634547 upstream.

The writeback thread would exit with a lock held when the cache device
is detached via sysfs interface, fix it by releasing the held lock
before exiting the while-loop.

Fixes: fadd94e05c02 (bcache: quit dc->writeback_thread when BCACHE_DEV_DETACHING is set)
Signed-off-by: Shan Hai <shan.hai@oracle.com>
Signed-off-by: Coly Li <colyli@suse.de>
Tested-by: Shenghui Wang <shhuiw@foxmail.com>
Cc: stable@vger.kernel.org #4.17+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index f2c0000de6137..95a6ae053714c 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -462,8 +462,10 @@ static int bch_writeback_thread(void *arg)
 			 * data on cache. BCACHE_DEV_DETACHING flag is set in
 			 * bch_cached_dev_detach().
 			 */
-			if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
+			if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)) {
+				up_write(&dc->writeback_lock);
 				break;
+			}
 		}
 
 		up_write(&dc->writeback_lock);