drbd: flush drbd work queue before invalidate/invalidate remote

If you do back to back wait-sync/invalidate on a Primary in a tight loop,
during application IO load, you could trigger a race:
  kernel: block drbd6: FIXME going to queue 'set_n_write from StartingSync'
    but 'write from resync_finished' still pending?

Fix this by changing the order of the drbd_queue_work() and
the wake_up() in dec_ap_pending(), and adding the additional
drbd_flush_workqueue() before requesting the full sync.

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_int.h b/drivers/block/drbd/drbd_int.h
index e010aff..22adfc7 100644 (file)
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -2251,15 +2251,17 @@ static inline void dec_ap_bio(struct drbd_conf *mdev)
        int ap_bio = atomic_dec_return(&mdev->ap_bio_cnt);
 
        D_ASSERT(ap_bio >= 0);
+
+       if (ap_bio == 0 && test_bit(BITMAP_IO, &mdev->flags)) {
+               if (!test_and_set_bit(BITMAP_IO_QUEUED, &mdev->flags))
+                       drbd_queue_work(&mdev->tconn->sender_work, &mdev->bm_io_work.w);
+       }
+
        /* this currently does wake_up for every dec_ap_bio!
         * maybe rather introduce some type of hysteresis?
         * e.g. (ap_bio == mxb/2 || ap_bio == 0) ? */
        if (ap_bio < mxb)
                wake_up(&mdev->misc_wait);
-       if (ap_bio == 0 && test_bit(BITMAP_IO, &mdev->flags)) {
-               if (!test_and_set_bit(BITMAP_IO_QUEUED, &mdev->flags))
-                       drbd_queue_work(&mdev->tconn->sender_work, &mdev->bm_io_work.w);
-       }
 }
 
 static inline int drbd_set_ed_uuid(struct drbd_conf *mdev, u64 val)

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index a2925de..4afd626 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -2408,9 +2408,11 @@ int drbd_adm_invalidate(struct sk_buff *skb, struct genl_info *info)
        mdev = adm_ctx.mdev;
 
        /* If there is still bitmap IO pending, probably because of a previous
-        * resync just being finished, wait for it before requesting a new resync. */
+        * resync just being finished, wait for it before requesting a new resync.
+        * Also wait for it's after_state_ch(). */
        drbd_suspend_io(mdev);
        wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
+       drbd_flush_workqueue(mdev);
 
        retcode = _drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_T), CS_ORDERED);
 
@@ -2475,9 +2477,11 @@ int drbd_adm_invalidate_peer(struct sk_buff *skb, struct genl_info *info)
        mdev = adm_ctx.mdev;
 
        /* If there is still bitmap IO pending, probably because of a previous
-        * resync just being finished, wait for it before requesting a new resync. */
+        * resync just being finished, wait for it before requesting a new resync.
+        * Also wait for it's after_state_ch(). */
        drbd_suspend_io(mdev);
        wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
+       drbd_flush_workqueue(mdev);
 
        retcode = _drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_S), CS_ORDERED);
        if (retcode < SS_SUCCESS) {