drbd: use test_and_set_bit() to decide if bm_io_work should be queued

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index f49505c..843b909 100644 (file)
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -3772,6 +3772,7 @@ static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused)
        drbd_bm_unlock(mdev);
 
        clear_bit(BITMAP_IO, &mdev->flags);
+       smp_mb__after_clear_bit();
        wake_up(&mdev->misc_wait);
 
        if (work->done)
@@ -3850,11 +3851,8 @@ void drbd_queue_bitmap_io(struct drbd_conf *mdev,
 
        set_bit(BITMAP_IO, &mdev->flags);
        if (atomic_read(&mdev->ap_bio_cnt) == 0) {
-               if (list_empty(&mdev->bm_io_work.w.list)) {
-                       set_bit(BITMAP_IO_QUEUED, &mdev->flags);
+               if (!test_and_set_bit(BITMAP_IO_QUEUED, &mdev->flags))
                        drbd_queue_work(&mdev->data.work, &mdev->bm_io_work.w);
-               } else
-                       dev_err(DEV, "FIXME avoided double queuing bm_io_work\n");
        }
 }