drbd: Cleaned up the resync timer logic

Besides removed a few lines of code, this moves the inspection
of the state from before the queuing process to after the queuing.
I.e. more closely to the actual invocation of the work.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_int.h

@@ -1540,7 +1540,7 @@ extern int w_e_end_csum_rs_req(struct drbd_conf *, struct drbd_work *, int);
 extern int w_e_end_ov_reply(struct drbd_conf *, struct drbd_work *, int);
 extern int w_e_end_ov_req(struct drbd_conf *, struct drbd_work *, int);
 extern int w_ov_finished(struct drbd_conf *, struct drbd_work *, int);
-extern int w_resync_inactive(struct drbd_conf *, struct drbd_work *, int);
+extern int w_resync_timer(struct drbd_conf *, struct drbd_work *, int);
 extern int w_resume_next_sg(struct drbd_conf *, struct drbd_work *, int);
 extern int w_send_write_hint(struct drbd_conf *, struct drbd_work *, int);
 extern int w_send_dblock(struct drbd_conf *, struct drbd_work *, int);

drivers/block/drbd/drbd_main.c

@@ -2978,7 +2978,7 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
 	INIT_LIST_HEAD(&mdev->start_resync_work.list);
 	INIT_LIST_HEAD(&mdev->bm_io_work.w.list);
 
-	mdev->resync_work.cb  = w_resync_inactive;
+	mdev->resync_work.cb  = w_resync_timer;
 	mdev->unplug_work.cb  = w_send_write_hint;
 	mdev->go_diskless.cb  = w_go_diskless;
 	mdev->md_sync_work.cb = w_md_sync;

drivers/block/drbd/drbd_worker.c

@@ -253,13 +253,6 @@ int w_read_retry_remote(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 	return w_send_read_req(mdev, w, 0);
 }
 
-int w_resync_inactive(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
-{
-	ERR_IF(cancel) return 1;
-	dev_err(DEV, "resync inactive, but callback triggered??\n");
-	return 1; /* Simply ignore this! */
-}
-
 void drbd_csum_ee(struct drbd_conf *mdev, struct crypto_hash *tfm, struct drbd_epoch_entry *e, void *digest)
 {
 	struct hash_desc desc;
@@ -389,26 +382,25 @@ static int read_for_csum(struct drbd_conf *mdev, sector_t sector, int size)
 	return -EAGAIN;
 }
 
-void resync_timer_fn(unsigned long data)
+int w_resync_timer(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 {
-	struct drbd_conf *mdev = (struct drbd_conf *) data;
-	int queue;
-
-	queue = 1;
 	switch (mdev->state.conn) {
 	case C_VERIFY_S:
-		mdev->resync_work.cb = w_make_ov_request;
+		w_make_ov_request(mdev, w, cancel);
 		break;
 	case C_SYNC_TARGET:
-		mdev->resync_work.cb = w_make_resync_request;
+		w_make_resync_request(mdev, w, cancel);
 		break;
-	default:
-		queue = 0;
-		mdev->resync_work.cb = w_resync_inactive;
 	}
 
-	/* harmless race: list_empty outside data.work.q_lock */
-	if (list_empty(&mdev->resync_work.list) && queue)
+	return 1;
+}
+
+void resync_timer_fn(unsigned long data)
+{
+	struct drbd_conf *mdev = (struct drbd_conf *) data;
+
+	if (list_empty(&mdev->resync_work.list))
 		drbd_queue_work(&mdev->data.work, &mdev->resync_work);
 }
 
@@ -525,15 +517,6 @@ static int w_make_resync_request(struct drbd_conf *mdev,
 	if (unlikely(cancel))
 		return 1;
 
-	if (unlikely(mdev->state.conn < C_CONNECTED)) {
-		dev_err(DEV, "Confused in w_make_resync_request()! cstate < Connected");
-		return 0;
-	}
-
-	if (mdev->state.conn != C_SYNC_TARGET)
-		dev_err(DEV, "%s in w_make_resync_request\n",
-			drbd_conn_str(mdev->state.conn));
-
 	if (mdev->rs_total == 0) {
 		/* empty resync? */
 		drbd_resync_finished(mdev);
@@ -546,7 +529,6 @@ static int w_make_resync_request(struct drbd_conf *mdev,
 		   to continue resync with a broken disk makes no sense at
 		   all */
 		dev_err(DEV, "Disk broke down during resync!\n");
-		mdev->resync_work.cb = w_resync_inactive;
 		return 1;
 	}
 
@@ -580,7 +562,6 @@ static int w_make_resync_request(struct drbd_conf *mdev,
 
 		if (bit == DRBD_END_OF_BITMAP) {
 			mdev->bm_resync_fo = drbd_bm_bits(mdev);
-			mdev->resync_work.cb = w_resync_inactive;
 			put_ldev(mdev);
 			return 1;
 		}
@@ -676,7 +657,6 @@ static int w_make_resync_request(struct drbd_conf *mdev,
 		 * resync data block, and the last bit is cleared.
 		 * until then resync "work" is "inactive" ...
 		 */
-		mdev->resync_work.cb = w_resync_inactive;
 		put_ldev(mdev);
 		return 1;
 	}
@@ -697,17 +677,11 @@ static int w_make_ov_request(struct drbd_conf *mdev, struct drbd_work *w, int ca
 	if (unlikely(cancel))
 		return 1;
 
-	if (unlikely(mdev->state.conn < C_CONNECTED)) {
-		dev_err(DEV, "Confused in w_make_ov_request()! cstate < Connected");
-		return 0;
-	}
-
 	number = drbd_rs_number_requests(mdev);
 
 	sector = mdev->ov_position;
 	for (i = 0; i < number; i++) {
 		if (sector >= capacity) {
-			mdev->resync_work.cb = w_resync_inactive;
 			return 1;
 		}