drbd: reduce code duplication when receiving data requests

also canonicalize the return values of read_for_csum
and drbd_rs_begin_io to return -ESOMETHING, or 0 for success.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_actlog.c

@@ -1119,7 +1119,7 @@ static int _is_in_al(struct drbd_conf *mdev, unsigned int enr)
  * @mdev:	DRBD device.
  * @sector:	The sector number.
  *
- * This functions sleeps on al_wait. Returns 1 on success, 0 if interrupted.
+ * This functions sleeps on al_wait. Returns 0 on success, -EINTR if interrupted.
  */
 int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector)
 {
@@ -1130,10 +1130,10 @@ int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector)
 	sig = wait_event_interruptible(mdev->al_wait,
 			(bm_ext = _bme_get(mdev, enr)));
 	if (sig)
-		return 0;
+		return -EINTR;
 
 	if (test_bit(BME_LOCKED, &bm_ext->flags))
-		return 1;
+		return 0;
 
 	for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
 		sig = wait_event_interruptible(mdev->al_wait,
@@ -1146,13 +1146,11 @@ int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector)
 				wake_up(&mdev->al_wait);
 			}
 			spin_unlock_irq(&mdev->al_lock);
-			return 0;
+			return -EINTR;
 		}
 	}
-
 	set_bit(BME_LOCKED, &bm_ext->flags);
-
-	return 1;
+	return 0;
 }
 
 /**

drivers/block/drbd/drbd_receiver.c

@@ -2068,21 +2068,12 @@ static int receive_DataRequest(struct drbd_conf *mdev, struct p_header *h)
 	case P_DATA_REQUEST:
 		e->w.cb = w_e_end_data_req;
 		fault_type = DRBD_FAULT_DT_RD;
-		break;
+		/* application IO, don't drbd_rs_begin_io */
+		goto submit;
+
 	case P_RS_DATA_REQUEST:
 		e->w.cb = w_e_end_rsdata_req;
 		fault_type = DRBD_FAULT_RS_RD;
-		/* Eventually this should become asynchronously. Currently it
-		 * blocks the whole receiver just to delay the reading of a
-		 * resync data block.
-		 * the drbd_work_queue mechanism is made for this...
-		 */
-		if (!drbd_rs_begin_io(mdev, sector)) {
-			/* we have been interrupted,
-			 * probably connection lost! */
-			D_ASSERT(signal_pending(current));
-			goto out_free_e;
-		}
 		break;
 
 	case P_OV_REPLY:
@@ -2108,13 +2099,8 @@ static int receive_DataRequest(struct drbd_conf *mdev, struct p_header *h)
 		} else if (h->command == P_OV_REPLY) {
 			e->w.cb = w_e_end_ov_reply;
 			dec_rs_pending(mdev);
-			break;
-		}
-
-		if (!drbd_rs_begin_io(mdev, sector)) {
-			/* we have been interrupted, probably connection lost! */
-			D_ASSERT(signal_pending(current));
-			goto out_free_e;
+			/* drbd_rs_begin_io done when we sent this request */
+			goto submit;
 		}
 		break;
 
@@ -2133,31 +2119,23 @@ static int receive_DataRequest(struct drbd_conf *mdev, struct p_header *h)
 		}
 		e->w.cb = w_e_end_ov_req;
 		fault_type = DRBD_FAULT_RS_RD;
-		/* Eventually this should become asynchronous. Currently it
-		 * blocks the whole receiver just to delay the reading of a
-		 * resync data block.
-		 * the drbd_work_queue mechanism is made for this...
-		 */
-		if (!drbd_rs_begin_io(mdev, sector)) {
-			/* we have been interrupted,
-			 * probably connection lost! */
-			D_ASSERT(signal_pending(current));
-			goto out_free_e;
-		}
 		break;
 
-
 	default:
 		dev_err(DEV, "unexpected command (%s) in receive_DataRequest\n",
 		    cmdname(h->command));
 		fault_type = DRBD_FAULT_MAX;
+		goto out_free_e;
 	}
 
-	spin_lock_irq(&mdev->req_lock);
-	list_add(&e->w.list, &mdev->read_ee);
-	spin_unlock_irq(&mdev->req_lock);
+	if (drbd_rs_begin_io(mdev, e->sector))
+		goto out_free_e;
 
+submit:
 	inc_unacked(mdev);
+	spin_lock_irq(&mdev->req_lock);
+	list_add_tail(&e->w.list, &mdev->read_ee);
+	spin_unlock_irq(&mdev->req_lock);
 
 	if (drbd_submit_ee(mdev, e, READ, fault_type) == 0)
 		return TRUE;

drivers/block/drbd/drbd_worker.c

@@ -374,26 +374,26 @@ static int read_for_csum(struct drbd_conf *mdev, sector_t sector, int size)
 	struct drbd_epoch_entry *e;
 
 	if (!get_ldev(mdev))
-		return 0;
+		return -EIO;
 
 	/* GFP_TRY, because if there is no memory available right now, this may
 	 * be rescheduled for later. It is "only" background resync, after all. */
 	e = drbd_alloc_ee(mdev, DRBD_MAGIC+0xbeef, sector, size, GFP_TRY);
 	if (!e)
-		goto fail;
+		goto defer;
 
+	e->w.cb = w_e_send_csum;
 	spin_lock_irq(&mdev->req_lock);
 	list_add(&e->w.list, &mdev->read_ee);
 	spin_unlock_irq(&mdev->req_lock);
 
-	e->w.cb = w_e_send_csum;
 	if (drbd_submit_ee(mdev, e, READ, DRBD_FAULT_RS_RD) == 0)
-		return 1;
+		return 0;
 
 	drbd_free_ee(mdev, e);
-fail:
+defer:
 	put_ldev(mdev);
-	return 2;
+	return -EAGAIN;
 }
 
 void resync_timer_fn(unsigned long data)
@@ -649,15 +649,19 @@ int w_make_resync_request(struct drbd_conf *mdev,
 			size = (capacity-sector)<<9;
 		if (mdev->agreed_pro_version >= 89 && mdev->csums_tfm) {
 			switch (read_for_csum(mdev, sector, size)) {
-			case 0: /* Disk failure*/
+			case -EIO: /* Disk failure */
 				put_ldev(mdev);
 				return 0;
-			case 2: /* Allocation failed */
+			case -EAGAIN: /* allocation failed, or ldev busy */
 				drbd_rs_complete_io(mdev, sector);
 				mdev->bm_resync_fo = BM_SECT_TO_BIT(sector);
 				i = rollback_i;
 				goto requeue;
-			/* case 1: everything ok */
+			case 0:
+				/* everything ok */
+				break;
+			default:
+				BUG();
 			}
 		} else {
 			inc_rs_pending(mdev);