Merge pull request #1881 from wswsmao/main

fuse passthrough: prefetchEntireFile just retry once to avoid exception stuck

fs/reader/reader.go

@@ -515,30 +515,33 @@ func (sf *file) GetPassthroughFd() (uintptr, error) {
 
 	id := genID(sf.id, firstChunkOffset, totalSize)
 
-	for {
-		// cache.PassThrough() is necessary to take over files
-		r, err := sf.gr.cache.Get(id, cache.PassThrough())
-		if err != nil {
-			if err := sf.prefetchEntireFile(); err != nil {
-				return 0, err
-			}
-			continue
+	// cache.PassThrough() is necessary to take over files
+	r, err := sf.gr.cache.Get(id, cache.PassThrough())
+	if err != nil {
+		if id, err = sf.prefetchEntireFile(); err != nil {
+			return 0, err
 		}
 
-		readerAt := r.GetReaderAt()
-		file, ok := readerAt.(*os.File)
-		if !ok {
-			r.Close()
-			return 0, fmt.Errorf("The cached ReaderAt is not of type *os.File, fd obtain failed")
+		// just retry once to avoid exception stuck
+		r, err = sf.gr.cache.Get(id, cache.PassThrough())
+		if err != nil {
+			return 0, err
 		}
+	}
 
-		fd := file.Fd()
+	readerAt := r.GetReaderAt()
+	file, ok := readerAt.(*os.File)
+	if !ok {
 		r.Close()
-		return fd, nil
+		return 0, fmt.Errorf("the cached ReaderAt is not of type *os.File, fd obtain failed")
 	}
+
+	fd := file.Fd()
+	r.Close()
+	return fd, nil
 }
 
-func (sf *file) prefetchEntireFile() error {
+func (sf *file) prefetchEntireFile() (string, error) {
 	var (
 		offset           int64
 		firstChunkOffset int64 = -1
@@ -581,11 +584,11 @@ func (sf *file) prefetchEntireFile() error {
 		// cache miss, prefetch the whole chunk
 		if _, err := sf.fr.ReadAt(ip, chunkOffset); err != nil && err != io.EOF {
 			sf.gr.putBuffer(b)
-			return fmt.Errorf("failed to read data: %w", err)
+			return "", fmt.Errorf("failed to read data: %w", err)
 		}
 		if err := sf.gr.verifyOneChunk(sf.id, ip, chunkDigestStr); err != nil {
 			sf.gr.putBuffer(b)
-			return err
+			return "", err
 		}
 		combinedBuffer.Write(ip)
 		totalSize += chunkSize
@@ -595,7 +598,7 @@ func (sf *file) prefetchEntireFile() error {
 	combinedIP := combinedBuffer.Bytes()
 	combinedID := genID(sf.id, firstChunkOffset, totalSize)
 	sf.gr.cacheData(combinedIP, combinedID)
-	return nil
+	return combinedID, nil
 }
 
 func (gr *reader) verifyOneChunk(entryID uint32, ip []byte, chunkDigestStr string) error {