writeback: bdi_writeback_task() must set task state before calling schedule()

Calling schedule without setting the task state to non-running will
return immediately, so ensure that we set it properly and check our
sleep conditions after doing so.

This is a fixup for commit 69b62d01.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 76f546d56a64..437a7431b4ea 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -978,8 +978,13 @@ int bdi_writeback_task(struct bdi_writeback *wb)
                 if (dirty_writeback_interval) {
                         wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
                         schedule_timeout_interruptible(wait_jiffies);
-                } else
-                        schedule();
+                } else {
+                        set_current_state(TASK_INTERRUPTIBLE);
+                        if (list_empty_careful(&wb->bdi->work_list) &&
+                            !kthread_should_stop())
+                                schedule();
+                        __set_current_state(TASK_RUNNING);
+                }
 
                 try_to_freeze();
         }