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>

1 files changed, 13 insertions, 9 deletions

diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 53b74254b1c2..f5d779b4d685 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/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 @@ next_sector:
                         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);