releases/4.14.69/bcache-release-dc-writeback_lock-properly-in-bch_writeback_thread.patch

   1 From 3943b040f11ed0cc6d4585fd286a623ca8634547 Mon Sep 17 00:00:00 2001
   2 From: Shan Hai <shan.hai@oracle.com>
   3 Date: Thu, 23 Aug 2018 02:02:56 +0800
   4 Subject: bcache: release dc->writeback_lock properly in bch_writeback_thread()
   5
   6 From: Shan Hai <shan.hai@oracle.com>
   7
   8 commit 3943b040f11ed0cc6d4585fd286a623ca8634547 upstream.
   9
  10 The writeback thread would exit with a lock held when the cache device
  11 is detached via sysfs interface, fix it by releasing the held lock
  12 before exiting the while-loop.
  13
  14 Fixes: fadd94e05c02 (bcache: quit dc->writeback_thread when BCACHE_DEV_DETACHING is set)
  15 Signed-off-by: Shan Hai <shan.hai@oracle.com>
  16 Signed-off-by: Coly Li <colyli@suse.de>
  17 Tested-by: Shenghui Wang <shhuiw@foxmail.com>
  18 Cc: stable@vger.kernel.org #4.17+
  19 Signed-off-by: Jens Axboe <axboe@kernel.dk>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  drivers/md/bcache/writeback.c |    4 +++-
  24  1 file changed, 3 insertions(+), 1 deletion(-)
  25
  26 --- a/drivers/md/bcache/writeback.c
  27 +++ b/drivers/md/bcache/writeback.c
  28 @@ -456,8 +456,10 @@ static int bch_writeback_thread(void *ar
  29                          * data on cache. BCACHE_DEV_DETACHING flag is set in
  30                          * bch_cached_dev_detach().
  31                          */
  32 -                       if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
  33 +                       if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)) {
  34 +                               up_write(&dc->writeback_lock);
  35                                 break;
  36 +                       }
  37                 }
  38
  39                 up_write(&dc->writeback_lock);