mount: cache on reading remote storage

weed/filesys/file.go

@@ -360,3 +360,30 @@ func (file *File) saveEntry(entry *filer_pb.Entry) error {
 func (file *File) getEntry() *filer_pb.Entry {
 	return file.entry
 }
+
+func (file *File) downloadRemoteEntry(entry *filer_pb.Entry) (*filer_pb.Entry, error) {
+	err := file.wfs.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
+
+		request := &filer_pb.DownloadToLocalRequest{
+			Directory: file.dir.FullPath(),
+			Name:      entry.Name,
+		}
+
+		glog.V(4).Infof("download entry: %v", request)
+		resp, err := client.DownloadToLocal(context.Background(), request)
+		if err != nil {
+			glog.Errorf("DownloadToLocal file %s/%s: %v", file.dir.FullPath(), file.Name, err)
+			return fuse.EIO
+		}
+
+		entry = resp.Entry
+
+		file.wfs.metaCache.InsertEntry(context.Background(), filer.FromPbEntry(request.Directory, resp.Entry))
+
+		file.dirtyMetadata = false
+
+		return nil
+	})
+
+	return entry, err
+}

weed/filesys/filehandle.go

@@ -114,6 +114,16 @@ func (fh *FileHandle) readFromChunks(buff []byte, offset int64) (int64, error) {
 		return 0, io.EOF
 	}
 
+	if entry.IsInRemoteOnly() {
+		glog.V(4).Infof("download remote entry %s", fh.f.fullpath())
+		newEntry, err := fh.f.downloadRemoteEntry(entry)
+		if err != nil {
+			glog.V(1).Infof("download remote entry %s: %v", fh.f.fullpath(), err)
+			return 0, err
+		}
+		entry = newEntry
+	}
+
 	fileSize := int64(filer.FileSize(entry))
 	fileFullPath := fh.f.fullpath()