volume: Don't unmount before deleting volume in copy

If we unmount first and then delete, the delete fails because the volume
was unmounted. Delete ends up doing the same thing as the unmount anyways.

weed/server/volume_grpc_copy.go

@@ -27,17 +27,12 @@ func (vs *VolumeServer) VolumeCopy(ctx context.Context, req *volume_server_pb.Vo
 
 		glog.V(0).Infof("volume %d already exists. deleted before copying...", req.VolumeId)
 
-		err := vs.store.UnmountVolume(needle.VolumeId(req.VolumeId))
-		if err != nil {
-			return nil, fmt.Errorf("failed to mount existing volume %d: %v", req.VolumeId, err)
-		}
-
-		err = vs.store.DeleteVolume(needle.VolumeId(req.VolumeId))
+		err := vs.store.DeleteVolume(needle.VolumeId(req.VolumeId))
 		if err != nil {
 			return nil, fmt.Errorf("failed to delete existing volume %d: %v", req.VolumeId, err)
 		}
 
-		glog.V(0).Infof("deleted exisitng volume %d before copying.", req.VolumeId)
+		glog.V(0).Infof("deleted existing volume %d before copying.", req.VolumeId)
 	}
 
 	location := vs.store.FindFreeLocation()

weed/storage/disk_location.go

@@ -174,6 +174,9 @@ func (l *DiskLocation) DeleteCollectionFromDiskLocation(collection string) (e er
 }
 
 func (l *DiskLocation) deleteVolumeById(vid needle.VolumeId) (found bool, e error) {
+	l.volumesLock.Lock()
+	defer l.volumesLock.Unlock()
+
 	v, ok := l.volumes[vid]
 	if !ok {
 		return

weed/storage/store.go

@@ -380,7 +380,7 @@ func (s *Store) DeleteVolume(i needle.VolumeId) error {
 		Ttl:              v.Ttl.ToUint32(),
 	}
 	for _, location := range s.Locations {
-		if found, error := location.deleteVolumeById(i); found && error == nil {
+		if found, err := location.deleteVolumeById(i); found && err == nil {
 			glog.V(0).Infof("DeleteVolume %d", i)
 			s.DeletedVolumesChan <- message
 			return nil