[PATCH] bcache: Fix a sleep-in-atomic bug

[Jia-Ju Bai]

The driver may sleep under a spin lock, and the function call path is:
journal_wait_for_write (acquire the lock by spin_lock)
  closure_sync
    schedule --> may sleep

To fix it, the lock is released before "closure_sync", and the lock is 
acquired again after this function.

Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxx>
---
 drivers/md/bcache/journal.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 1198e53..ad47c36 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -724,6 +724,7 @@ static struct journal_write *journal_wait_for_write(struct cache_set *c,
 			btree_flush_write(c);
 		}
 
+		spin_unlock(&c->journal.lock);
 		closure_sync(&cl);
 		spin_lock(&c->journal.lock);
 		wait = true;
-- 
1.7.9.5