drbd: Do no sleep long in drbd_start_resync

Work items that sleep too long can cause requests to take as
long as the longest sleeping work item.

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

1 files changed, 36 insertions, 22 deletions

diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 28925d3d1a2f..a705979c71f8 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -1487,35 +1487,49 @@ void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side)
                    Ahead/Behind and SyncSource/SyncTarget */
         }
 
-        if (side == C_SYNC_TARGET) {
-                /* Since application IO was locked out during C_WF_BITMAP_T and
-                   C_WF_SYNC_UUID we are still unmodified. Before going to C_SYNC_TARGET
-                   we check that we might make the data inconsistent. */
-                r = drbd_khelper(mdev, "before-resync-target");
-                r = (r >> 8) & 0xff;
-                if (r > 0) {
-                        dev_info(DEV, "before-resync-target handler returned %d, "
-                             "dropping connection.\n", r);
-                        drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
-                        return;
-                }
-        } else /* C_SYNC_SOURCE */ {
-                r = drbd_khelper(mdev, "before-resync-source");
-                r = (r >> 8) & 0xff;
-                if (r > 0) {
-                        if (r == 3) {
-                                dev_info(DEV, "before-resync-source handler returned %d, "
-                                         "ignoring. Old userland tools?", r);
-                        } else {
-                                dev_info(DEV, "before-resync-source handler returned %d, "
+        if (!test_bit(B_RS_H_DONE, &mdev->flags)) {
+                if (side == C_SYNC_TARGET) {
+                        /* Since application IO was locked out during C_WF_BITMAP_T and
+                           C_WF_SYNC_UUID we are still unmodified. Before going to C_SYNC_TARGET
+                           we check that we might make the data inconsistent. */
+                        r = drbd_khelper(mdev, "before-resync-target");
+                        r = (r >> 8) & 0xff;
+                        if (r > 0) {
+                                dev_info(DEV, "before-resync-target handler returned %d, "
                                          "dropping connection.\n", r);
                                 drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
                                 return;
                         }
+                } else /* C_SYNC_SOURCE */ {
+                        r = drbd_khelper(mdev, "before-resync-source");
+                        r = (r >> 8) & 0xff;
+                        if (r > 0) {
+                                if (r == 3) {
+                                        dev_info(DEV, "before-resync-source handler returned %d, "
+                                                 "ignoring. Old userland tools?", r);
+                                } else {
+                                        dev_info(DEV, "before-resync-source handler returned %d, "
+                                                 "dropping connection.\n", r);
+                                        drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
+                                        return;
+                                }
+                        }
                 }
         }
 
-        drbd_state_lock(mdev);
+        if (current == mdev->tconn->worker.task) {
+                /* The worker should not sleep waiting for drbd_state_lock(),
+                   that can take long */
+                if (test_and_set_bit(CLUSTER_ST_CHANGE, &mdev->flags)) {
+                        set_bit(B_RS_H_DONE, &mdev->flags);
+                        mdev->start_resync_timer.expires = jiffies + HZ/5;
+                        add_timer(&mdev->start_resync_timer);
+                        return;
+                }
+        } else {
+                drbd_state_lock(mdev);
+        }
+        clear_bit(B_RS_H_DONE, &mdev->flags);
 
         if (!get_ldev_if_state(mdev, D_NEGOTIATING)) {
                 drbd_state_unlock(mdev);