br: revert "Add retry limit of connection err in fine grained backup" (#58496)

Author: RidRisR

br/pkg/backup/client.go

@@ -118,7 +118,6 @@ const (
 	// We need to be more patient.
 	backupFineGrainedMaxBackoff = 3600000
 	backupRetryTimes            = 5
-	disconnectRetryTimeout      = 20000
 	// RangeUnit represents the progress updated counter when a range finished.
 	RangeUnit ProgressUnit = "range"
 	// RegionUnit represents the progress updated counter when a region finished.
@@ -1159,7 +1158,6 @@ func (bc *Client) fineGrainedBackup(
 	})
 
 	bo := utils.AdaptTiKVBackoffer(ctx, backupFineGrainedMaxBackoff, berrors.ErrUnknown)
-	maxDisconnect := make(map[uint64]uint)
 	for {
 		// Step1, check whether there is any incomplete range
 		incomplete := pr.Res.GetIncompleteRange(req.StartKey, req.EndKey)
@@ -1207,19 +1205,8 @@ func (bc *Client) fineGrainedBackup(
 		for {
 			select {
 			case err := <-errCh:
-				if !berrors.Is(err, berrors.ErrFailedToConnect) {
-					return errors.Trace(err)
-				}
-				storeErr, ok := err.(*StoreBasedErr)
-				if !ok {
-					return errors.Trace(err)
-				}
-
-				storeID := storeErr.storeID
-				maxDisconnect[storeID]++
-				if maxDisconnect[storeID] > backupRetryTimes {
-					return errors.Annotatef(err, "Failed to connect to store %d more than %d times", storeID, backupRetryTimes)
-				}
+				// TODO: should we handle err here?
+				return errors.Trace(err)
 			case resp, ok := <-respCh:
 				if !ok {
 					// Finished.
@@ -1332,10 +1319,7 @@ func (bc *Client) handleFineGrained(
 			// When the leader store is died,
 			// 20s for the default max duration before the raft election timer fires.
 			logutil.CL(ctx).Warn("failed to connect to store, skipping", logutil.ShortError(err), zap.Uint64("storeID", storeID))
-			return disconnectRetryTimeout, &StoreBasedErr{
-				storeID: storeID,
-				err:     err,
-			}
+			return 20000, nil
 		}
 
 		logutil.CL(ctx).Error("fail to connect store", zap.Uint64("StoreID", storeID))
@@ -1374,10 +1358,7 @@ func (bc *Client) handleFineGrained(
 			// When the leader store is died,
 			// 20s for the default max duration before the raft election timer fires.
 			logutil.CL(ctx).Warn("failed to connect to store, skipping", logutil.ShortError(err), zap.Uint64("storeID", storeID))
-			return disconnectRetryTimeout, &StoreBasedErr{
-				storeID: storeID,
-				err:     err,
-			}
+			return 20000, nil
 		}
 		logutil.CL(ctx).Error("failed to send fine-grained backup", zap.Uint64("storeID", storeID), logutil.ShortError(err))
 		return 0, errors.Annotatef(err, "failed to send fine-grained backup [%s, %s)",