Btrfs: fix race in worker_loop

Need to check kthread_should_stop after schedule_timeout() before calling
schedule(). This causes threads to sleep with potentially no one to wake them
up causing mount(2) to hang in btrfs_stop_workers waiting for threads to stop.

Signed-off-by: Amit Gud <gud@ksu.edu>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index c84ca1f5259a..cba701dba350 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -195,6 +195,9 @@ again_locked:
                                 if (!list_empty(&worker->pending))
                                         continue;
 
+                                if (kthread_should_stop())
+                                        break;
+
                                 /* still no more work?, sleep for real */
                                 spin_lock_irq(&worker->lock);
                                 set_current_state(TASK_INTERRUPTIBLE);
@@ -208,7 +211,8 @@ again_locked:
                                 worker->working = 0;
                                 spin_unlock_irq(&worker->lock);
 
-                                schedule();
+                                if (!kthread_should_stop())
+                                        schedule();
                         }
                         __set_current_state(TASK_RUNNING);
                 }