Streaming bitrot verification support (#7004)

cmd/bitrot-streaming.go

@@ -0,0 +1,172 @@
+/*
+ * Minio Cloud Storage, (C) 2019 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"bytes"
+	"context"
+	"encoding/hex"
+	"hash"
+	"io"
+
+	"github.com/minio/minio/cmd/logger"
+)
+
+// Calculates bitrot in chunks and writes the hash into the stream.
+type streamingBitrotWriter struct {
+	iow       *io.PipeWriter
+	h         hash.Hash
+	shardSize int64
+	canClose  chan struct{} // Needed to avoid race explained in Close() call.
+
+	// Following two fields are used only to make sure that Write(p) is called such that
+	// len(p) is always the block size except the last block, i.e prevent programmer errors.
+	currentBlockIdx int
+	verifyTillIdx   int
+}
+
+func (b *streamingBitrotWriter) Write(p []byte) (int, error) {
+	if b.currentBlockIdx < b.verifyTillIdx && int64(len(p)) != b.shardSize {
+		// All blocks except last should be of the length b.shardSize
+		logger.LogIf(context.Background(), errUnexpected)
+		return 0, errUnexpected
+	}
+	if len(p) == 0 {
+		return 0, nil
+	}
+	b.h.Reset()
+	b.h.Write(p)
+	hashBytes := b.h.Sum(nil)
+	n, err := b.iow.Write(hashBytes)
+	if n != len(hashBytes) {
+		logger.LogIf(context.Background(), err)
+		return 0, err
+	}
+	n, err = b.iow.Write(p)
+	b.currentBlockIdx++
+	return n, err
+}
+
+func (b *streamingBitrotWriter) Close() error {
+	err := b.iow.Close()
+	// Wait for all data to be written before returning else it causes race conditions.
+	// Race condition is because of io.PipeWriter implementation. i.e consider the following
+	// sequent of operations:
+	// 1) pipe.Write()
+	// 2) pipe.Close()
+	// Now pipe.Close() can return before the data is read on the other end of the pipe and written to the disk
+	// Hence an immediate Read() on the file can return incorrect data.
+	<-b.canClose
+	return err
+}
+
+// Returns streaming bitrot writer implementation.
+func newStreamingBitrotWriter(disk StorageAPI, volume, filePath string, length int64, algo BitrotAlgorithm, shardSize int64) io.WriteCloser {
+	r, w := io.Pipe()
+	h := algo.New()
+	bw := &streamingBitrotWriter{w, h, shardSize, make(chan struct{}), 0, int(length / shardSize)}
+	go func() {
+		bitrotSumsTotalSize := ceilFrac(length, shardSize) * int64(h.Size()) // Size used for storing bitrot checksums.
+		totalFileSize := bitrotSumsTotalSize + length
+		err := disk.CreateFile(volume, filePath, totalFileSize, r)
+		if err != nil {
+			logger.LogIf(context.Background(), err)
+			r.CloseWithError(err)
+		}
+		close(bw.canClose)
+	}()
+	return bw
+}
+
+// ReadAt() implementation which verifies the bitrot hash available as part of the stream.
+type streamingBitrotReader struct {
+	disk       StorageAPI
+	rc         io.ReadCloser
+	volume     string
+	filePath   string
+	tillOffset int64
+	currOffset int64
+	h          hash.Hash
+	shardSize  int64
+	hashBytes  []byte
+}
+
+func (b *streamingBitrotReader) Close() error {
+	if b.rc == nil {
+		return nil
+	}
+	return b.rc.Close()
+}
+
+func (b *streamingBitrotReader) ReadAt(buf []byte, offset int64) (int, error) {
+	var err error
+	if offset%b.shardSize != 0 {
+		// Offset should always be aligned to b.shardSize
+		logger.LogIf(context.Background(), errUnexpected)
+		return 0, errUnexpected
+	}
+	if b.rc == nil {
+		// For the first ReadAt() call we need to open the stream for reading.
+		b.currOffset = offset
+		streamOffset := (offset/b.shardSize)*int64(b.h.Size()) + offset
+		b.rc, err = b.disk.ReadFileStream(b.volume, b.filePath, streamOffset, b.tillOffset-streamOffset)
+		if err != nil {
+			logger.LogIf(context.Background(), err)
+			return 0, err
+		}
+	}
+	if offset != b.currOffset {
+		logger.LogIf(context.Background(), errUnexpected)
+		return 0, errUnexpected
+	}
+	b.h.Reset()
+	_, err = io.ReadFull(b.rc, b.hashBytes)
+	if err != nil {
+		logger.LogIf(context.Background(), err)
+		return 0, err
+	}
+	_, err = io.ReadFull(b.rc, buf)
+	if err != nil {
+		logger.LogIf(context.Background(), err)
+		return 0, err
+	}
+	b.h.Write(buf)
+
+	if bytes.Compare(b.h.Sum(nil), b.hashBytes) != 0 {
+		err = hashMismatchError{hex.EncodeToString(b.hashBytes), hex.EncodeToString(b.h.Sum(nil))}
+		logger.LogIf(context.Background(), err)
+		return 0, err
+	}
+	b.currOffset += int64(len(buf))
+	return len(buf), nil
+}
+
+// Returns streaming bitrot reader implementation.
+func newStreamingBitrotReader(disk StorageAPI, volume, filePath string, tillOffset int64, algo BitrotAlgorithm, shardSize int64) *streamingBitrotReader {
+	h := algo.New()
+	return &streamingBitrotReader{
+		disk,
+		nil,
+		volume,
+		filePath,
+		ceilFrac(tillOffset, shardSize)*int64(h.Size()) + tillOffset,
+		0,
+		h,
+		shardSize,
+		make([]byte, h.Size()),
+	}
+}

cmd/bitrot-whole.go

@@ -0,0 +1,109 @@
+/*
+ * Minio Cloud Storage, (C) 2019 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"context"
+	"hash"
+	"io"
+
+	"github.com/minio/minio/cmd/logger"
+)
+
+// Implementation to calculate bitrot for the whole file.
+type wholeBitrotWriter struct {
+	disk      StorageAPI
+	volume    string
+	filePath  string
+	shardSize int64 // This is the shard size of the erasure logic
+	hash.Hash       // For bitrot hash
+
+	// Following two fields are used only to make sure that Write(p) is called such that
+	// len(p) is always the block size except the last block and prevent programmer errors.
+	currentBlockIdx int
+	lastBlockIdx    int
+}
+
+func (b *wholeBitrotWriter) Write(p []byte) (int, error) {
+	if b.currentBlockIdx < b.lastBlockIdx && int64(len(p)) != b.shardSize {
+		// All blocks except last should be of the length b.shardSize
+		logger.LogIf(context.Background(), errUnexpected)
+		return 0, errUnexpected
+	}
+	err := b.disk.AppendFile(b.volume, b.filePath, p)
+	if err != nil {
+		logger.LogIf(context.Background(), err)
+		return 0, err
+	}
+	_, err = b.Hash.Write(p)
+	if err != nil {
+		logger.LogIf(context.Background(), err)
+		return 0, err
+	}
+	b.currentBlockIdx++
+	return len(p), nil
+}
+
+func (b *wholeBitrotWriter) Close() error {
+	return nil
+}
+
+// Returns whole-file bitrot writer.
+func newWholeBitrotWriter(disk StorageAPI, volume, filePath string, length int64, algo BitrotAlgorithm, shardSize int64) io.WriteCloser {
+	return &wholeBitrotWriter{disk, volume, filePath, shardSize, algo.New(), 0, int(length / shardSize)}
+}
+
+// Implementation to verify bitrot for the whole file.
+type wholeBitrotReader struct {
+	disk       StorageAPI
+	volume     string
+	filePath   string
+	verifier   *BitrotVerifier // Holds the bit-rot info
+	tillOffset int64           // Affects the length of data requested in disk.ReadFile depending on Read()'s offset
+	buf        []byte          // Holds bit-rot verified data
+}
+
+func (b *wholeBitrotReader) ReadAt(buf []byte, offset int64) (n int, err error) {
+	if b.buf == nil {
+		b.buf = make([]byte, b.tillOffset-offset)
+		if _, err := b.disk.ReadFile(b.volume, b.filePath, offset, b.buf, b.verifier); err != nil {
+			ctx := context.Background()
+			logger.GetReqInfo(ctx).AppendTags("disk", b.disk.String())
+			logger.LogIf(ctx, err)
+			return 0, err
+		}
+	}
+	if len(b.buf) < len(buf) {
+		logger.LogIf(context.Background(), errLessData)
+		return 0, errLessData
+	}
+	n = copy(buf, b.buf)
+	b.buf = b.buf[n:]
+	return n, nil
+}
+
+// Returns whole-file bitrot reader.
+func newWholeBitrotReader(disk StorageAPI, volume, filePath string, algo BitrotAlgorithm, tillOffset int64, sum []byte) *wholeBitrotReader {
+	return &wholeBitrotReader{
+		disk:       disk,
+		volume:     volume,
+		filePath:   filePath,
+		verifier:   &BitrotVerifier{algo, sum},
+		tillOffset: tillOffset,
+		buf:        nil,
+	}
+}

cmd/bitrot.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"errors"
 	"hash"
+	"io"
 
 	"github.com/minio/highwayhash"
 	"github.com/minio/minio/cmd/logger"
@@ -38,19 +39,22 @@ const (
 	SHA256 BitrotAlgorithm = 1 + iota
 	// HighwayHash256 represents the HighwayHash-256 hash function
 	HighwayHash256
+	// HighwayHash256 represents the Streaming HighwayHash-256 hash function
+	HighwayHash256S
 	// BLAKE2b512 represents the BLAKE2b-512 hash function
 	BLAKE2b512
 )
 
 // DefaultBitrotAlgorithm is the default algorithm used for bitrot protection.
 const (
-	DefaultBitrotAlgorithm = HighwayHash256
+	DefaultBitrotAlgorithm = HighwayHash256S
 )
 
 var bitrotAlgorithms = map[BitrotAlgorithm]string{
-	SHA256:         "sha256",
+	SHA256:          "sha256",
-	BLAKE2b512:     "blake2b",
+	BLAKE2b512:      "blake2b",
-	HighwayHash256: "highwayhash256",
+	HighwayHash256:  "highwayhash256",
+	HighwayHash256S: "highwayhash256S",
 }
 
 // New returns a new hash.Hash calculating the given bitrot algorithm.
@@ -64,6 +68,9 @@ func (a BitrotAlgorithm) New() hash.Hash {
 	case HighwayHash256:
 		hh, _ := highwayhash.New(magicHighwayHash256Key) // New will never return error since key is 256 bit
 		return hh
+	case HighwayHash256S:
+		hh, _ := highwayhash.New(magicHighwayHash256Key) // New will never return error since key is 256 bit
+		return hh
 	default:
 		logger.CriticalIf(context.Background(), errors.New("Unsupported bitrot algorithm"))
 		return nil
@@ -109,86 +116,71 @@ func BitrotAlgorithmFromString(s string) (a BitrotAlgorithm) {
 	return
 }
 
-// To read bit-rot verified data.
+func newBitrotWriter(disk StorageAPI, volume, filePath string, length int64, algo BitrotAlgorithm, shardSize int64) io.Writer {
-type bitrotReader struct {
+	if algo == HighwayHash256S {
-	disk      StorageAPI
+		return newStreamingBitrotWriter(disk, volume, filePath, length, algo, shardSize)
-	volume    string
+	}
-	filePath  string
+	return newWholeBitrotWriter(disk, volume, filePath, length, algo, shardSize)
-	verifier  *BitrotVerifier // Holds the bit-rot info
-	endOffset int64           // Affects the length of data requested in disk.ReadFile depending on Read()'s offset
-	buf       []byte          // Holds bit-rot verified data
 }
 
-// newBitrotReader returns bitrotReader.
+func newBitrotReader(disk StorageAPI, bucket string, filePath string, tillOffset int64, algo BitrotAlgorithm, sum []byte, shardSize int64) io.ReaderAt {
-// Note that the buffer is allocated later in Read(). This is because we will know the buffer length only
+	if algo == HighwayHash256S {
-// during the bitrotReader.Read(). Depending on when parallelReader fails-over, the buffer length can be different.
+		return newStreamingBitrotReader(disk, bucket, filePath, tillOffset, algo, shardSize)
-func newBitrotReader(disk StorageAPI, volume, filePath string, algo BitrotAlgorithm, endOffset int64, sum []byte) *bitrotReader {
-	return &bitrotReader{
-		disk:      disk,
-		volume:    volume,
-		filePath:  filePath,
-		verifier:  &BitrotVerifier{algo, sum},
-		endOffset: endOffset,
-		buf:       nil,
 	}
+	return newWholeBitrotReader(disk, bucket, filePath, algo, tillOffset, sum)
 }
 
-// ReadChunk returns requested data.
+// Close all the readers.
-func (b *bitrotReader) ReadChunk(offset int64, length int64) ([]byte, error) {
+func closeBitrotReaders(rs []io.ReaderAt) {
-	if b.buf == nil {
+	for _, r := range rs {
-		b.buf = make([]byte, b.endOffset-offset)
+		if br, ok := r.(*streamingBitrotReader); ok {
-		if _, err := b.disk.ReadFile(b.volume, b.filePath, offset, b.buf, b.verifier); err != nil {
+			br.Close()
-			ctx := context.Background()
-			logger.GetReqInfo(ctx).AppendTags("disk", b.disk.String())
-			logger.LogIf(ctx, err)
-			return nil, err
 		}
 	}
-	if int64(len(b.buf)) < length {
-		logger.LogIf(context.Background(), errLessData)
-		return nil, errLessData
-	}
-	retBuf := b.buf[:length]
-	b.buf = b.buf[length:]
-	return retBuf, nil
 }
 
-// To calculate the bit-rot of the written data.
+// Close all the writers.
-type bitrotWriter struct {
+func closeBitrotWriters(ws []io.Writer) {
-	disk     StorageAPI
+	for _, w := range ws {
-	volume   string
+		if bw, ok := w.(*streamingBitrotWriter); ok {
-	filePath string
+			bw.Close()
-	h        hash.Hash
+		}
+	}
 }
 
-// newBitrotWriter returns bitrotWriter.
+// Returns hash sum for whole-bitrot, nil for streaming-bitrot.
-func newBitrotWriter(disk StorageAPI, volume, filePath string, algo BitrotAlgorithm) *bitrotWriter {
+func bitrotWriterSum(w io.Writer) []byte {
-	return &bitrotWriter{
+	if bw, ok := w.(*wholeBitrotWriter); ok {
-		disk:     disk,
+		return bw.Sum(nil)
-		volume:   volume,
-		filePath: filePath,
-		h:        algo.New(),
 	}
+	return nil
 }
 
-// Append appends the data and while calculating the hash.
+// Verify if a file has bitrot error.
-func (b *bitrotWriter) Append(buf []byte) error {
+func bitrotCheckFile(disk StorageAPI, volume string, filePath string, tillOffset int64, algo BitrotAlgorithm, sum []byte, shardSize int64) (err error) {
-	n, err := b.h.Write(buf)
+	buf := make([]byte, shardSize)
-	if err != nil {
+	if algo != HighwayHash256S {
+		// For whole-file bitrot we don't need to read the entire file as the bitrot verify happens on the server side even if we read small buffer
+		_, err = disk.ReadFile(volume, filePath, 0, buf, NewBitrotVerifier(algo, sum))
 		return err
 	}
-	if n != len(buf) {
+	r := newStreamingBitrotReader(disk, volume, filePath, tillOffset, algo, shardSize)
-		logger.LogIf(context.Background(), errUnexpected)
+	defer closeBitrotReaders([]io.ReaderAt{r})
-		return errUnexpected
+	var offset int64
-	}
+	for {
-	if err = b.disk.AppendFile(b.volume, b.filePath, buf); err != nil {
+		if offset == tillOffset {
-		logger.LogIf(context.Background(), err)
+			break
-		return err
+		}
+		var n int
+		tmpBuf := buf
+		if int64(len(tmpBuf)) > (tillOffset - offset) {
+			tmpBuf = tmpBuf[:(tillOffset - offset)]
+		}
+		n, err = r.ReadAt(tmpBuf, offset)
+		if err != nil {
+			return err
+		}
+		offset += int64(n)
 	}
 	return nil
 }
-
-// Sum returns bit-rot sum.
-func (b *bitrotWriter) Sum() []byte {
-	return b.h.Sum(nil)
-}

cmd/bitrot_test.go

@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
@@ -40,32 +41,38 @@ func TestBitrotReaderWriter(t *testing.T) {
 
 	disk.MakeVol(volume)
 
-	writer := newBitrotWriter(disk, volume, filePath, HighwayHash256)
+	writer := newBitrotWriter(disk, volume, filePath, 35, HighwayHash256S, 10)
 
-	err = writer.Append([]byte("aaaaaaaaa"))
+	_, err = writer.Write([]byte("aaaaaaaaaa"))
 	if err != nil {
 		log.Fatal(err)
 	}
-	err = writer.Append([]byte("a"))
+	_, err = writer.Write([]byte("aaaaaaaaaa"))
 	if err != nil {
 		log.Fatal(err)
 	}
-	err = writer.Append([]byte("aaaaaaaaaa"))
+	_, err = writer.Write([]byte("aaaaaaaaaa"))
 	if err != nil {
 		log.Fatal(err)
 	}
-	err = writer.Append([]byte("aaaaa"))
+	_, err = writer.Write([]byte("aaaaa"))
 	if err != nil {
 		log.Fatal(err)
 	}
-	err = writer.Append([]byte("aaaaaaaaaa"))
+	writer.(io.Closer).Close()
-	if err != nil {
+
+	reader := newStreamingBitrotReader(disk, volume, filePath, 35, HighwayHash256S, 10)
+	b := make([]byte, 10)
+	if _, err = reader.ReadAt(b, 0); err != nil {
 		log.Fatal(err)
 	}
-
+	if _, err = reader.ReadAt(b, 10); err != nil {
-	reader := newBitrotReader(disk, volume, filePath, HighwayHash256, 35, writer.Sum())
+		log.Fatal(err)
-
+	}
-	if _, err = reader.ReadChunk(0, 35); err != nil {
+	if _, err = reader.ReadAt(b, 20); err != nil {
+		log.Fatal(err)
+	}
+	if _, err = reader.ReadAt(b[:5], 30); err != nil {
 		log.Fatal(err)
 	}
 }

cmd/erasure-decode.go

@@ -23,25 +23,25 @@ import (
 	"github.com/minio/minio/cmd/logger"
 )
 
-// Reads in parallel from bitrotReaders.
+// Reads in parallel from readers.
 type parallelReader struct {
-	readers       []*bitrotReader
+	readers       []io.ReaderAt
 	dataBlocks    int
 	offset        int64
 	shardSize     int64
 	shardFileSize int64
+	buf           [][]byte
 }
 
 // newParallelReader returns parallelReader.
-func newParallelReader(readers []*bitrotReader, dataBlocks int, offset int64, fileSize int64, blocksize int64) *parallelReader {
+func newParallelReader(readers []io.ReaderAt, e Erasure, offset, totalLength int64) *parallelReader {
-	shardSize := ceilFrac(blocksize, int64(dataBlocks))
-	shardFileSize := getErasureShardFileSize(blocksize, fileSize, dataBlocks)
 	return &parallelReader{
 		readers,
-		dataBlocks,
+		e.dataBlocks,
-		(offset / blocksize) * shardSize,
+		(offset / e.blockSize) * e.ShardSize(),
-		shardSize,
+		e.ShardSize(),
-		shardFileSize,
+		e.ShardFileSize(totalLength),
+		make([][]byte, len(readers)),
 	}
 }
 
@@ -56,7 +56,7 @@ func (p *parallelReader) canDecode(buf [][]byte) bool {
 	return bufCount >= p.dataBlocks
 }
 
-// Read reads from bitrotReaders in parallel. Returns p.dataBlocks number of bufs.
+// Read reads from readers in parallel. Returns p.dataBlocks number of bufs.
 func (p *parallelReader) Read() ([][]byte, error) {
 	type errIdx struct {
 		idx int
@@ -73,8 +73,12 @@ func (p *parallelReader) Read() ([][]byte, error) {
 	}
 
 	read := func(currReaderIndex int) {
-		b, err := p.readers[currReaderIndex].ReadChunk(p.offset, p.shardSize)
+		if p.buf[currReaderIndex] == nil {
-		errCh <- errIdx{currReaderIndex, b, err}
+			p.buf[currReaderIndex] = make([]byte, p.shardSize)
+		}
+		p.buf[currReaderIndex] = p.buf[currReaderIndex][:p.shardSize]
+		_, err := p.readers[currReaderIndex].ReadAt(p.buf[currReaderIndex], p.offset)
+		errCh <- errIdx{currReaderIndex, p.buf[currReaderIndex], err}
 	}
 
 	readerCount := 0
@@ -128,7 +132,7 @@ func (p *parallelReader) Read() ([][]byte, error) {
 }
 
 // Decode reads from readers, reconstructs data if needed and writes the data to the writer.
-func (e Erasure) Decode(ctx context.Context, writer io.Writer, readers []*bitrotReader, offset, length, totalLength int64) error {
+func (e Erasure) Decode(ctx context.Context, writer io.Writer, readers []io.ReaderAt, offset, length, totalLength int64) error {
 	if offset < 0 || length < 0 {
 		logger.LogIf(ctx, errInvalidArgument)
 		return errInvalidArgument
@@ -141,7 +145,7 @@ func (e Erasure) Decode(ctx context.Context, writer io.Writer, readers []*bitrot
 		return nil
 	}
 
-	reader := newParallelReader(readers, e.dataBlocks, offset, totalLength, e.blockSize)
+	reader := newParallelReader(readers, e, offset, totalLength)
 
 	startBlock := offset / e.blockSize
 	endBlock := (offset + length) / e.blockSize

cmd/erasure-decode_test.go

@@ -41,26 +41,28 @@ var erasureDecodeTests = []struct {
 	algorithm                    BitrotAlgorithm
 	shouldFail, shouldFailQuorum bool
 }{
-	{dataBlocks: 2, onDisks: 4, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},                                                         // 0
+	{dataBlocks: 2, onDisks: 4, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},             // 0
-	{dataBlocks: 3, onDisks: 6, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false},                                                             // 1
+	{dataBlocks: 3, onDisks: 6, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false},                 // 1
-	{dataBlocks: 4, onDisks: 8, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                             // 2
+	{dataBlocks: 4, onDisks: 8, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 2
-	{dataBlocks: 5, onDisks: 10, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 1, length: oneMiByte - 1, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},                                                    // 3
+	{dataBlocks: 5, onDisks: 10, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 1, length: oneMiByte - 1, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},        // 3
-	{dataBlocks: 6, onDisks: 12, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: oneMiByte, length: 0, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},                                                          // 4
+	{dataBlocks: 6, onDisks: 12, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: oneMiByte, length: 0, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},
-	{dataBlocks: 7, onDisks: 14, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: 3, length: 1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                                   // 5
+	// 4
-	{dataBlocks: 8, onDisks: 16, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: 4, length: 8 * 1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                               // 6
+	{dataBlocks: 7, onDisks: 14, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: 3, length: 1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                    // 5
-	{dataBlocks: 7, onDisks: 14, offDisks: 7, blocksize: int64(blockSizeV1), data: oneMiByte, offset: oneMiByte, length: 1, algorithm: DefaultBitrotAlgorithm, shouldFail: true, shouldFailQuorum: false},                                             // 7
+	{dataBlocks: 8, onDisks: 16, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: 4, length: 8 * 1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                // 6
-	{dataBlocks: 6, onDisks: 12, offDisks: 6, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                            // 8
+	{dataBlocks: 7, onDisks: 14, offDisks: 7, blocksize: int64(blockSizeV1), data: oneMiByte, offset: oneMiByte, length: 1, algorithm: DefaultBitrotAlgorithm, shouldFail: true, shouldFailQuorum: false},              // 7
-	{dataBlocks: 5, onDisks: 10, offDisks: 5, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},                                                          // 9
+	{dataBlocks: 6, onDisks: 12, offDisks: 6, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},             // 8
-	{dataBlocks: 4, onDisks: 8, offDisks: 4, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false},                                                             // 10
+	{dataBlocks: 5, onDisks: 10, offDisks: 5, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},                           // 9
-	{dataBlocks: 3, onDisks: 6, offDisks: 3, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                               // 11
+	{dataBlocks: 4, onDisks: 8, offDisks: 4, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false},                              // 10
-	{dataBlocks: 2, onDisks: 4, offDisks: 2, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                             // 12
+	{dataBlocks: 3, onDisks: 6, offDisks: 3, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                // 11
-	{dataBlocks: 2, onDisks: 4, offDisks: 1, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                               // 13
+	{dataBlocks: 2, onDisks: 4, offDisks: 2, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},              // 12
-	{dataBlocks: 3, onDisks: 6, offDisks: 2, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                               // 14
+	{dataBlocks: 2, onDisks: 4, offDisks: 1, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                // 13
-	{dataBlocks: 4, onDisks: 8, offDisks: 3, blocksize: int64(2 * oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                           // 15
+	{dataBlocks: 3, onDisks: 6, offDisks: 2, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                // 14
-	{dataBlocks: 5, onDisks: 10, offDisks: 6, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: true},                                               // 16
+	{dataBlocks: 4, onDisks: 8, offDisks: 3, blocksize: int64(2 * oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},            // 15
-	{dataBlocks: 5, onDisks: 10, offDisks: 2, blocksize: int64(blockSizeV1), data: 2 * oneMiByte, offset: oneMiByte, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                // 17
+	{dataBlocks: 5, onDisks: 10, offDisks: 6, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: true},                // 16
-	{dataBlocks: 5, onDisks: 10, offDisks: 1, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},                                                        // 18
+	{dataBlocks: 5, onDisks: 10, offDisks: 2, blocksize: int64(blockSizeV1), data: 2 * oneMiByte, offset: oneMiByte, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 17
-	{dataBlocks: 6, onDisks: 12, offDisks: 3, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false},                                                            // 19
+	{dataBlocks: 5, onDisks: 10, offDisks: 1, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},                         // 18
+	{dataBlocks: 6, onDisks: 12, offDisks: 3, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false},
+	// 19
 	{dataBlocks: 6, onDisks: 12, offDisks: 7, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: true},                                             // 20
 	{dataBlocks: 8, onDisks: 16, offDisks: 8, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                                            // 21
 	{dataBlocks: 8, onDisks: 16, offDisks: 9, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: true},                                               // 22
@@ -104,11 +106,12 @@ func TestErasureDecode(t *testing.T) {
 			writeAlgorithm = DefaultBitrotAlgorithm
 		}
 		buffer := make([]byte, test.blocksize, 2*test.blocksize)
-		writers := make([]*bitrotWriter, len(disks))
+		writers := make([]io.Writer, len(disks))
 		for i, disk := range disks {
-			writers[i] = newBitrotWriter(disk, "testbucket", "object", writeAlgorithm)
+			writers[i] = newBitrotWriter(disk, "testbucket", "object", erasure.ShardFileSize(test.data), writeAlgorithm, erasure.ShardSize())
 		}
 		n, err := erasure.Encode(context.Background(), bytes.NewReader(data[:]), writers, buffer, erasure.dataBlocks+1)
+		closeBitrotWriters(writers)
 		if err != nil {
 			setup.Remove()
 			t.Fatalf("Test %d: failed to create erasure test file: %v", i, err)
@@ -124,17 +127,19 @@ func TestErasureDecode(t *testing.T) {
 		}
 
 		// Get the checksums of the current part.
-		bitrotReaders := make([]*bitrotReader, len(disks))
+		bitrotReaders := make([]io.ReaderAt, len(disks))
 		for index, disk := range disks {
 			if disk == OfflineDisk {
 				continue
 			}
-			endOffset := getErasureShardFileEndOffset(test.offset, test.length, test.data, test.blocksize, erasure.dataBlocks)
+			tillOffset := erasure.ShardFileTillOffset(test.offset, test.length, test.data)
-			bitrotReaders[index] = newBitrotReader(disk, "testbucket", "object", writeAlgorithm, endOffset, writers[index].Sum())
+
+			bitrotReaders[index] = newBitrotReader(disk, "testbucket", "object", tillOffset, writeAlgorithm, bitrotWriterSum(writers[index]), erasure.ShardSize())
 		}
 
 		writer := bytes.NewBuffer(nil)
 		err = erasure.Decode(context.Background(), writer, bitrotReaders, test.offset, test.length, test.data)
+		closeBitrotReaders(bitrotReaders)
 		if err != nil && !test.shouldFail {
 			t.Errorf("Test %d: should pass but failed with: %v", i, err)
 		}
@@ -143,31 +148,41 @@ func TestErasureDecode(t *testing.T) {
 		}
 		if err == nil {
 			if content := writer.Bytes(); !bytes.Equal(content, data[test.offset:test.offset+test.length]) {
-				t.Errorf("Test %d: read retruns wrong file content", i)
+				t.Errorf("Test %d: read retruns wrong file content.", i)
 			}
 		}
+
 		for i, r := range bitrotReaders {
 			if r == nil {
 				disks[i] = OfflineDisk
 			}
 		}
 		if err == nil && !test.shouldFail {
-			bitrotReaders = make([]*bitrotReader, len(disks))
+			bitrotReaders = make([]io.ReaderAt, len(disks))
 			for index, disk := range disks {
 				if disk == OfflineDisk {
 					continue
 				}
-				endOffset := getErasureShardFileEndOffset(test.offset, test.length, test.data, test.blocksize, erasure.dataBlocks)
+				tillOffset := erasure.ShardFileTillOffset(test.offset, test.length, test.data)
-				bitrotReaders[index] = newBitrotReader(disk, "testbucket", "object", writeAlgorithm, endOffset, writers[index].Sum())
+				bitrotReaders[index] = newBitrotReader(disk, "testbucket", "object", tillOffset, writeAlgorithm, bitrotWriterSum(writers[index]), erasure.ShardSize())
 			}
 			for j := range disks[:test.offDisks] {
-				bitrotReaders[j].disk = badDisk{nil}
+				if bitrotReaders[j] == nil {
+					continue
+				}
+				switch r := bitrotReaders[j].(type) {
+				case *wholeBitrotReader:
+					r.disk = badDisk{nil}
+				case *streamingBitrotReader:
+					r.disk = badDisk{nil}
+				}
 			}
 			if test.offDisks > 0 {
 				bitrotReaders[0] = nil
 			}
 			writer.Reset()
 			err = erasure.Decode(context.Background(), writer, bitrotReaders, test.offset, test.length, test.data)
+			closeBitrotReaders(bitrotReaders)
 			if err != nil && !test.shouldFailQuorum {
 				t.Errorf("Test %d: should pass but failed with: %v", i, err)
 			}
@@ -213,12 +228,12 @@ func TestErasureDecodeRandomOffsetLength(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	writers := make([]*bitrotWriter, len(disks))
+	writers := make([]io.Writer, len(disks))
 	for i, disk := range disks {
 		if disk == nil {
 			continue
 		}
-		writers[i] = newBitrotWriter(disk, "testbucket", "object", DefaultBitrotAlgorithm)
+		writers[i] = newBitrotWriter(disk, "testbucket", "object", erasure.ShardFileSize(length), DefaultBitrotAlgorithm, erasure.ShardSize())
 	}
 
 	// 10000 iterations with random offsets and lengths.
@@ -227,6 +242,7 @@ func TestErasureDecodeRandomOffsetLength(t *testing.T) {
 	// Create a test file to read from.
 	buffer := make([]byte, blockSize, 2*blockSize)
 	n, err := erasure.Encode(context.Background(), bytes.NewReader(data), writers, buffer, erasure.dataBlocks+1)
+	closeBitrotWriters(writers)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -247,15 +263,16 @@ func TestErasureDecodeRandomOffsetLength(t *testing.T) {
 		expected := data[offset : offset+readLen]
 
 		// Get the checksums of the current part.
-		bitrotReaders := make([]*bitrotReader, len(disks))
+		bitrotReaders := make([]io.ReaderAt, len(disks))
 		for index, disk := range disks {
 			if disk == OfflineDisk {
 				continue
 			}
-			endOffset := getErasureShardFileEndOffset(offset, readLen, length, blockSize, erasure.dataBlocks)
+			tillOffset := erasure.ShardFileTillOffset(offset, readLen, length)
-			bitrotReaders[index] = newBitrotReader(disk, "testbucket", "object", DefaultBitrotAlgorithm, endOffset, writers[index].Sum())
+			bitrotReaders[index] = newStreamingBitrotReader(disk, "testbucket", "object", tillOffset, DefaultBitrotAlgorithm, erasure.ShardSize())
 		}
 		err = erasure.Decode(context.Background(), buf, bitrotReaders, offset, readLen, length)
+		closeBitrotReaders(bitrotReaders)
 		if err != nil {
 			t.Fatal(err, offset, readLen)
 		}
@@ -281,17 +298,18 @@ func benchmarkErasureDecode(data, parity, dataDown, parityDown int, size int64,
 		b.Fatalf("failed to create ErasureStorage: %v", err)
 	}
 
-	writers := make([]*bitrotWriter, len(disks))
+	writers := make([]io.Writer, len(disks))
 	for i, disk := range disks {
 		if disk == nil {
 			continue
 		}
-		writers[i] = newBitrotWriter(disk, "testbucket", "object", DefaultBitrotAlgorithm)
+		writers[i] = newBitrotWriter(disk, "testbucket", "object", erasure.ShardFileSize(size), DefaultBitrotAlgorithm, erasure.ShardSize())
 	}
 
 	content := make([]byte, size)
 	buffer := make([]byte, blockSizeV1, 2*blockSizeV1)
 	_, err = erasure.Encode(context.Background(), bytes.NewReader(content), writers, buffer, erasure.dataBlocks+1)
+	closeBitrotWriters(writers)
 	if err != nil {
 		b.Fatalf("failed to create erasure test file: %v", err)
 	}
@@ -307,17 +325,18 @@ func benchmarkErasureDecode(data, parity, dataDown, parityDown int, size int64,
 	b.SetBytes(size)
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
-		bitrotReaders := make([]*bitrotReader, len(disks))
+		bitrotReaders := make([]io.ReaderAt, len(disks))
 		for index, disk := range disks {
 			if writers[index] == nil {
 				continue
 			}
-			endOffset := getErasureShardFileEndOffset(0, size, size, erasure.blockSize, erasure.dataBlocks)
+			tillOffset := erasure.ShardFileTillOffset(0, size, size)
-			bitrotReaders[index] = newBitrotReader(disk, "testbucket", "object", DefaultBitrotAlgorithm, endOffset, writers[index].Sum())
+			bitrotReaders[index] = newStreamingBitrotReader(disk, "testbucket", "object", tillOffset, DefaultBitrotAlgorithm, erasure.ShardSize())
 		}
 		if err = erasure.Decode(context.Background(), bytes.NewBuffer(content[:0]), bitrotReaders, 0, size, size); err != nil {
 			panic(err)
 		}
+		closeBitrotReaders(bitrotReaders)
 	}
 }
 

cmd/erasure-encode.go

@@ -25,15 +25,15 @@ import (
 	"github.com/minio/minio/cmd/logger"
 )
 
-// Writes in parallel to bitrotWriters
+// Writes in parallel to writers
 type parallelWriter struct {
-	writers     []*bitrotWriter
+	writers     []io.Writer
 	writeQuorum int
 	errs        []error
 }
 
-// Append appends data to bitrotWriters in parallel.
+// Write writes data to writers in parallel.
-func (p *parallelWriter) Append(ctx context.Context, blocks [][]byte) error {
+func (p *parallelWriter) Write(ctx context.Context, blocks [][]byte) error {
 	var wg sync.WaitGroup
 
 	for i := range p.writers {
@@ -45,7 +45,7 @@ func (p *parallelWriter) Append(ctx context.Context, blocks [][]byte) error {
 		wg.Add(1)
 		go func(i int) {
 			defer wg.Done()
-			p.errs[i] = p.writers[i].Append(blocks[i])
+			_, p.errs[i] = p.writers[i].Write(blocks[i])
 			if p.errs[i] != nil {
 				p.writers[i] = nil
 			}
@@ -70,7 +70,7 @@ func (p *parallelWriter) Append(ctx context.Context, blocks [][]byte) error {
 }
 
 // Encode reads from the reader, erasure-encodes the data and writes to the writers.
-func (e *Erasure) Encode(ctx context.Context, src io.Reader, writers []*bitrotWriter, buf []byte, quorum int) (total int64, err error) {
+func (e *Erasure) Encode(ctx context.Context, src io.Reader, writers []io.Writer, buf []byte, quorum int) (total int64, err error) {
 	writer := &parallelWriter{
 		writers:     writers,
 		writeQuorum: quorum,
@@ -96,7 +96,7 @@ func (e *Erasure) Encode(ctx context.Context, src io.Reader, writers []*bitrotWr
 			return 0, err
 		}
 
-		if err = writer.Append(ctx, blocks); err != nil {
+		if err = writer.Write(ctx, blocks); err != nil {
 			logger.LogIf(ctx, err)
 			return 0, err
 		}

cmd/erasure-encode_test.go

@@ -36,6 +36,14 @@ func (a badDisk) AppendFile(volume string, path string, buf []byte) error {
 	return errFaultyDisk
 }
 
+func (a badDisk) ReadFileStream(volume, path string, offset, length int64) (io.ReadCloser, error) {
+	return nil, errFaultyDisk
+}
+
+func (a badDisk) CreateFile(volume, path string, size int64, reader io.Reader) error {
+	return errFaultyDisk
+}
+
 const oneMiByte = 1 * humanize.MiByte
 
 var erasureEncodeTests = []struct {
@@ -87,14 +95,15 @@ func TestErasureEncode(t *testing.T) {
 			setup.Remove()
 			t.Fatalf("Test %d: failed to generate random test data: %v", i, err)
 		}
-		writers := make([]*bitrotWriter, len(disks))
+		writers := make([]io.Writer, len(disks))
 		for i, disk := range disks {
 			if disk == OfflineDisk {
 				continue
 			}
-			writers[i] = newBitrotWriter(disk, "testbucket", "object", test.algorithm)
+			writers[i] = newBitrotWriter(disk, "testbucket", "object", erasure.ShardFileSize(int64(len(data[test.offset:]))), test.algorithm, erasure.ShardSize())
 		}
 		n, err := erasure.Encode(context.Background(), bytes.NewReader(data[test.offset:]), writers, buffer, erasure.dataBlocks+1)
+		closeBitrotWriters(writers)
 		if err != nil && !test.shouldFail {
 			t.Errorf("Test %d: should pass but failed with: %v", i, err)
 		}
@@ -110,20 +119,26 @@ func TestErasureEncode(t *testing.T) {
 			if length := int64(len(data[test.offset:])); n != length {
 				t.Errorf("Test %d: invalid number of bytes written: got: #%d want #%d", i, n, length)
 			}
-			writers := make([]*bitrotWriter, len(disks))
+			writers := make([]io.Writer, len(disks))
 			for i, disk := range disks {
 				if disk == nil {
 					continue
 				}
-				writers[i] = newBitrotWriter(disk, "testbucket", "object2", test.algorithm)
+				writers[i] = newBitrotWriter(disk, "testbucket", "object2", erasure.ShardFileSize(int64(len(data[test.offset:]))), test.algorithm, erasure.ShardSize())
 			}
 			for j := range disks[:test.offDisks] {
-				writers[j].disk = badDisk{nil}
+				switch w := writers[j].(type) {
+				case *wholeBitrotWriter:
+					w.disk = badDisk{nil}
+				case *streamingBitrotWriter:
+					w.iow.CloseWithError(errFaultyDisk)
+				}
 			}
 			if test.offDisks > 0 {
 				writers[0] = nil
 			}
 			n, err = erasure.Encode(context.Background(), bytes.NewReader(data[test.offset:]), writers, buffer, erasure.dataBlocks+1)
+			closeBitrotWriters(writers)
 			if err != nil && !test.shouldFailQuorum {
 				t.Errorf("Test %d: should pass but failed with: %v", i, err)
 			}
@@ -167,14 +182,16 @@ func benchmarkErasureEncode(data, parity, dataDown, parityDown int, size int64,
 	b.SetBytes(size)
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
-		writers := make([]*bitrotWriter, len(disks))
+		writers := make([]io.Writer, len(disks))
 		for i, disk := range disks {
 			if disk == OfflineDisk {
 				continue
 			}
-			writers[i] = newBitrotWriter(disk, "testbucket", "object", DefaultBitrotAlgorithm)
+			disk.DeleteFile("testbucket", "object")
+			writers[i] = newBitrotWriter(disk, "testbucket", "object", erasure.ShardFileSize(size), DefaultBitrotAlgorithm, erasure.ShardSize())
 		}
 		_, err := erasure.Encode(context.Background(), bytes.NewReader(content), writers, buffer, erasure.dataBlocks+1)
+		closeBitrotWriters(writers)
 		if err != nil {
 			panic(err)
 		}

cmd/erasure-heal.go

@@ -25,7 +25,7 @@ import (
 
 // Heal heals the shard files on non-nil writers. Note that the quorum passed is 1
 // as healing should continue even if it has been successful healing only one shard file.
-func (e Erasure) Heal(ctx context.Context, readers []*bitrotReader, writers []*bitrotWriter, size int64) error {
+func (e Erasure) Heal(ctx context.Context, readers []io.ReaderAt, writers []io.Writer, size int64) error {
 	r, w := io.Pipe()
 	go func() {
 		if err := e.Decode(ctx, w, readers, 0, size, size); err != nil {

cmd/erasure-heal_test.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"crypto/rand"
 	"io"
+	"os"
 	"testing"
 )
 
@@ -84,20 +85,21 @@ func TestErasureHeal(t *testing.T) {
 			t.Fatalf("Test %d: failed to create random test data: %v", i, err)
 		}
 		buffer := make([]byte, test.blocksize, 2*test.blocksize)
-		writers := make([]*bitrotWriter, len(disks))
+		writers := make([]io.Writer, len(disks))
 		for i, disk := range disks {
-			writers[i] = newBitrotWriter(disk, "testbucket", "testobject", test.algorithm)
+			writers[i] = newBitrotWriter(disk, "testbucket", "testobject", erasure.ShardFileSize(test.size), test.algorithm, erasure.ShardSize())
 		}
 		_, err = erasure.Encode(context.Background(), bytes.NewReader(data), writers, buffer, erasure.dataBlocks+1)
+		closeBitrotWriters(writers)
 		if err != nil {
 			setup.Remove()
 			t.Fatalf("Test %d: failed to create random test data: %v", i, err)
 		}
 
-		readers := make([]*bitrotReader, len(disks))
+		readers := make([]io.ReaderAt, len(disks))
 		for i, disk := range disks {
-			shardFilesize := getErasureShardFileSize(test.blocksize, test.size, erasure.dataBlocks)
+			shardFilesize := erasure.ShardFileSize(test.size)
-			readers[i] = newBitrotReader(disk, "testbucket", "testobject", test.algorithm, shardFilesize, writers[i].Sum())
+			readers[i] = newBitrotReader(disk, "testbucket", "testobject", shardFilesize, test.algorithm, bitrotWriterSum(writers[i]), erasure.ShardSize())
 		}
 
 		// setup stale disks for the test case
@@ -111,22 +113,30 @@ func TestErasureHeal(t *testing.T) {
 			}
 		}
 		for j := 0; j < test.badDisks; j++ {
-			readers[test.offDisks+j].disk = badDisk{nil}
+			switch r := readers[test.offDisks+j].(type) {
+			case *streamingBitrotReader:
+				r.disk = badDisk{nil}
+			case *wholeBitrotReader:
+				r.disk = badDisk{nil}
+			}
 		}
 		for j := 0; j < test.badStaleDisks; j++ {
 			staleDisks[j] = badDisk{nil}
 		}
 
-		staleWriters := make([]*bitrotWriter, len(staleDisks))
+		staleWriters := make([]io.Writer, len(staleDisks))
 		for i, disk := range staleDisks {
 			if disk == nil {
 				continue
 			}
-			staleWriters[i] = newBitrotWriter(disk, "testbucket", "testobject", test.algorithm)
+			os.Remove(pathJoin(disk.String(), "testbucket", "testobject"))
+			staleWriters[i] = newBitrotWriter(disk, "testbucket", "testobject", erasure.ShardFileSize(test.size), test.algorithm, erasure.ShardSize())
 		}
 
-		// test case setup is complete - now call Healfile()
+		// test case setup is complete - now call Heal()
 		err = erasure.Heal(context.Background(), readers, staleWriters, test.size)
+		closeBitrotReaders(readers)
+		closeBitrotWriters(staleWriters)
 		if err != nil && !test.shouldFail {
 			t.Errorf("Test %d: should pass but it failed with: %v", i, err)
 		}
@@ -140,7 +150,7 @@ func TestErasureHeal(t *testing.T) {
 				if staleWriters[i] == nil {
 					continue
 				}
-				if !bytes.Equal(staleWriters[i].Sum(), writers[i].Sum()) {
+				if !bytes.Equal(bitrotWriterSum(staleWriters[i]), bitrotWriterSum(writers[i])) {
 					t.Errorf("Test %d: heal returned different bitrot checksums", i)
 				}
 			}

cmd/erasure-utils.go

@@ -109,25 +109,3 @@ func writeDataBlocks(ctx context.Context, dst io.Writer, enBlocks [][]byte, data
 	// Success.
 	return totalWritten, nil
 }
-
-// Returns shard-file size.
-func getErasureShardFileSize(blockSize int64, totalLength int64, dataBlocks int) int64 {
-	shardSize := ceilFrac(int64(blockSize), int64(dataBlocks))
-	numShards := totalLength / int64(blockSize)
-	lastBlockSize := totalLength % int64(blockSize)
-	lastShardSize := ceilFrac(lastBlockSize, int64(dataBlocks))
-	return shardSize*numShards + lastShardSize
-}
-
-// Returns the endOffset till which bitrotReader should read data using disk.ReadFile()
-// partOffset, partLength and partSize are values of the object's part file.
-func getErasureShardFileEndOffset(partOffset int64, partLength int64, partSize int64, erasureBlockSize int64, dataBlocks int) int64 {
-	shardSize := ceilFrac(erasureBlockSize, int64(dataBlocks))
-	shardFileSize := getErasureShardFileSize(erasureBlockSize, partSize, dataBlocks)
-	endShard := (partOffset + int64(partLength)) / erasureBlockSize
-	endOffset := endShard*shardSize + shardSize
-	if endOffset > shardFileSize {
-		endOffset = shardFileSize
-	}
-	return endOffset
-}

cmd/erasure.go

@@ -32,18 +32,16 @@ type Erasure struct {
 
 // NewErasure creates a new ErasureStorage.
 func NewErasure(ctx context.Context, dataBlocks, parityBlocks int, blockSize int64) (e Erasure, err error) {
-	shardsize := int(ceilFrac(blockSize, int64(dataBlocks)))
-	erasure, err := reedsolomon.New(dataBlocks, parityBlocks, reedsolomon.WithAutoGoroutines(shardsize))
-	if err != nil {
-		logger.LogIf(ctx, err)
-		return e, err
-	}
 	e = Erasure{
-		encoder:      erasure,
 		dataBlocks:   dataBlocks,
 		parityBlocks: parityBlocks,
 		blockSize:    blockSize,
 	}
+	e.encoder, err = reedsolomon.New(dataBlocks, parityBlocks, reedsolomon.WithAutoGoroutines(int(e.ShardSize())))
+	if err != nil {
+		logger.LogIf(ctx, err)
+		return e, err
+	}
 	return
 }
 
@@ -94,3 +92,28 @@ func (e *Erasure) DecodeDataAndParityBlocks(ctx context.Context, data [][]byte)
 	}
 	return nil
 }
+
+func (e *Erasure) ShardSize() int64 {
+	return ceilFrac(e.blockSize, int64(e.dataBlocks))
+}
+
+func (e *Erasure) ShardFileSize(totalLength int64) int64 {
+	if totalLength == 0 {
+		return 0
+	}
+	numShards := totalLength / e.blockSize
+	lastBlockSize := totalLength % int64(e.blockSize)
+	lastShardSize := ceilFrac(lastBlockSize, int64(e.dataBlocks))
+	return numShards*e.ShardSize() + lastShardSize
+}
+
+func (e *Erasure) ShardFileTillOffset(startOffset, length, totalLength int64) int64 {
+	shardSize := e.ShardSize()
+	shardFileSize := e.ShardFileSize(totalLength)
+	endShard := (startOffset + int64(length)) / e.blockSize
+	tillOffset := endShard*shardSize + shardSize
+	if tillOffset > shardFileSize {
+		tillOffset = shardFileSize
+	}
+	return tillOffset
+}

cmd/naughty-disk_test.go

@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"io"
 	"sync"
 )
 
@@ -124,11 +125,18 @@ func (d *naughtyDisk) ReadFile(volume string, path string, offset int64, buf []b
 	return d.disk.ReadFile(volume, path, offset, buf, verifier)
 }
 
-func (d *naughtyDisk) PrepareFile(volume, path string, length int64) error {
+func (d *naughtyDisk) ReadFileStream(volume, path string, offset, length int64) (io.ReadCloser, error) {
+	if err := d.calcError(); err != nil {
+		return nil, err
+	}
+	return d.disk.ReadFileStream(volume, path, offset, length)
+}
+
+func (d *naughtyDisk) CreateFile(volume, path string, size int64, reader io.Reader) error {
 	if err := d.calcError(); err != nil {
 		return err
 	}
-	return d.disk.PrepareFile(volume, path, length)
+	return d.disk.CreateFile(volume, path, size, reader)
 }
 
 func (d *naughtyDisk) AppendFile(volume, path string, buf []byte) error {

cmd/posix.go

@@ -928,11 +928,99 @@ func (s *posix) openFile(volume, path string, mode int) (f *os.File, err error)
 	return w, nil
 }
 
-// PrepareFile - run prior actions before creating a new file for optimization purposes
+// Just like io.LimitedReader but supports Close() to be compatible with io.ReadCloser that is
-// Currently we use fallocate when available to avoid disk fragmentation as much as possible
+// returned by posix.ReadFileStream()
-func (s *posix) PrepareFile(volume, path string, fileSize int64) (err error) {
+type posixLimitedReader struct {
-	// It doesn't make sense to create a negative-sized file
+	io.LimitedReader
-	if fileSize < -1 {
+}
+
+func (l *posixLimitedReader) Close() error {
+	c, ok := l.R.(io.Closer)
+	if !ok {
+		return errUnexpected
+	}
+	return c.Close()
+}
+
+// ReadFileStream - Returns the read stream of the file.
+func (s *posix) ReadFileStream(volume, path string, offset, length int64) (io.ReadCloser, error) {
+	var err error
+	defer func() {
+		if err == errFaultyDisk {
+			atomic.AddInt32(&s.ioErrCount, 1)
+		}
+	}()
+
+	if offset < 0 {
+		return nil, errInvalidArgument
+	}
+
+	if atomic.LoadInt32(&s.ioErrCount) > maxAllowedIOError {
+		return nil, errFaultyDisk
+	}
+
+	if err = s.checkDiskFound(); err != nil {
+		return nil, err
+	}
+
+	volumeDir, err := s.getVolDir(volume)
+	if err != nil {
+		return nil, err
+	}
+	// Stat a volume entry.
+	_, err = os.Stat((volumeDir))
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, errVolumeNotFound
+		} else if isSysErrIO(err) {
+			return nil, errFaultyDisk
+		}
+		return nil, err
+	}
+
+	// Validate effective path length before reading.
+	filePath := pathJoin(volumeDir, path)
+	if err = checkPathLength((filePath)); err != nil {
+		return nil, err
+	}
+
+	// Open the file for reading.
+	file, err := os.Open((filePath))
+	if err != nil {
+		switch {
+		case os.IsNotExist(err):
+			return nil, errFileNotFound
+		case os.IsPermission(err):
+			return nil, errFileAccessDenied
+		case isSysErrNotDir(err):
+			return nil, errFileAccessDenied
+		case isSysErrIO(err):
+			return nil, errFaultyDisk
+		default:
+			return nil, err
+		}
+	}
+
+	st, err := file.Stat()
+	if err != nil {
+		return nil, err
+	}
+
+	// Verify it is a regular file, otherwise subsequent Seek is
+	// undefined.
+	if !st.Mode().IsRegular() {
+		return nil, errIsNotRegular
+	}
+
+	if _, err = file.Seek(offset, io.SeekStart); err != nil {
+		return nil, err
+	}
+	return &posixLimitedReader{io.LimitedReader{file, length}}, nil
+}
+
+// CreateFile - creates the file.
+func (s *posix) CreateFile(volume, path string, fileSize int64, r io.Reader) (err error) {
+	if fileSize < 0 {
 		return errInvalidArgument
 	}
 
@@ -954,13 +1042,13 @@ func (s *posix) PrepareFile(volume, path string, fileSize int64) (err error) {
 		return err
 	}
 
-	// Create file if not found
+	// Create file if not found. Note that it is created with os.O_EXCL flag as the file
-	w, err := s.openFile(volume, path, os.O_CREATE|os.O_APPEND|os.O_WRONLY)
+	// always is supposed to be created in the tmp directory with a unique file name.
+	w, err := s.openFile(volume, path, os.O_CREATE|os.O_APPEND|os.O_WRONLY|os.O_EXCL)
 	if err != nil {
 		return err
 	}
 
-	// Close upon return.
 	defer w.Close()
 
 	var e error
@@ -983,6 +1071,20 @@ func (s *posix) PrepareFile(volume, path string, fileSize int64) (err error) {
 		}
 		return err
 	}
+
+	bufp := s.pool.Get().(*[]byte)
+	defer s.pool.Put(bufp)
+
+	n, err := io.CopyBuffer(w, r, *bufp)
+	if err != nil {
+		return err
+	}
+	if n < fileSize {
+		return errLessData
+	}
+	if n > fileSize {
+		return errMoreData
+	}
 	return nil
 }
 

cmd/posix_test.go

@@ -1438,113 +1438,6 @@ func TestPosixAppendFile(t *testing.T) {
 	}
 }
 
-// TestPosix posix.PrepareFile()
-func TestPosixPrepareFile(t *testing.T) {
-	// create posix test setup
-	posixStorage, path, err := newPosixTestSetup()
-	if err != nil {
-		t.Fatalf("Unable to create posix test setup, %s", err)
-	}
-	defer os.RemoveAll(path)
-
-	// Setup test environment.
-	if err = posixStorage.MakeVol("success-vol"); err != nil {
-		t.Fatalf("Unable to create volume, %s", err)
-	}
-
-	if err = os.Mkdir(slashpath.Join(path, "success-vol", "object-as-dir"), 0777); err != nil {
-		t.Fatalf("Unable to create directory, %s", err)
-	}
-
-	testCases := []struct {
-		fileName    string
-		expectedErr error
-	}{
-		{"myobject", nil},
-		{"path/to/my/object", nil},
-		// TestPosix to append to previously created file.
-		{"myobject", nil},
-		// TestPosix to use same path of previously created file.
-		{"path/to/my/testobject", nil},
-		{"object-as-dir", errIsNotRegular},
-		// path segment uses previously uploaded object.
-		{"myobject/testobject", errFileAccessDenied},
-		// One path segment length is > 255 chars long.
-		{"path/to/my/object0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", errFileNameTooLong},
-	}
-
-	// Add path length > 1024 test specially as OS X system does not support 1024 long path.
-	err = errFileNameTooLong
-	if runtime.GOOS != "darwin" {
-		err = nil
-	}
-	// path length is 1024 chars long.
-	testCases = append(testCases, struct {
-		fileName    string
-		expectedErr error
-	}{"level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", err})
-
-	for i, testCase := range testCases {
-		if err = posixStorage.PrepareFile("success-vol", testCase.fileName, 16); err != testCase.expectedErr {
-			t.Errorf("Case: %d, expected: %s, got: %s", i, testCase.expectedErr, err)
-		}
-	}
-
-	// TestPosix for permission denied.
-	if runtime.GOOS != globalWindowsOSName {
-		permDeniedDir := createPermDeniedFile(t)
-		defer removePermDeniedFile(permDeniedDir)
-
-		var posixPermStorage StorageAPI
-		// Initialize posix storage layer for permission denied error.
-		_, err = newPosix(permDeniedDir)
-		if err != nil && !os.IsPermission(err) {
-			t.Fatalf("Unable to initialize posix, %s", err)
-		}
-
-		if err = os.Chmod(permDeniedDir, 0755); err != nil {
-			t.Fatalf("Unable to change permission to temporary directory %v. %v", permDeniedDir, err)
-		}
-
-		posixPermStorage, err = newPosix(permDeniedDir)
-		if err != nil {
-			t.Fatalf("Unable to initialize posix, %s", err)
-		}
-
-		if err = posixPermStorage.PrepareFile("mybucket", "myobject", 16); err != errFileAccessDenied {
-			t.Fatalf("expected: Permission error, got: %s", err)
-		}
-	}
-
-	// TestPosix case with invalid volume name.
-	// A valid volume name should be atleast of size 3.
-	err = posixStorage.PrepareFile("bn", "yes", 16)
-	if err != errVolumeNotFound {
-		t.Fatalf("expected: \"Invalid argument error\", got: \"%s\"", err)
-	}
-
-	// TestPosix case with invalid file size which should be strictly positive
-	err = posixStorage.PrepareFile("success-vol", "yes", -3)
-	if err != errInvalidArgument {
-		t.Fatalf("should fail: %v", err)
-	}
-
-	// TestPosix case with IO error count > max limit.
-
-	// setting ioErrCnt to 6.
-	// should fail with errFaultyDisk.
-	if posixType, ok := posixStorage.(*posix); ok {
-		// setting the io error count from as specified in the test case.
-		posixType.ioErrCount = int32(6)
-		err = posixType.PrepareFile("abc", "yes", 16)
-		if err != errFaultyDisk {
-			t.Fatalf("Expected \"Faulty Disk\", got: \"%s\"", err)
-		}
-	} else {
-		t.Fatalf("Expected the StorageAPI to be of type *posix")
-	}
-}
-
 // TestPosix posix.RenameFile()
 func TestPosixRenameFile(t *testing.T) {
 	// create posix test setup

cmd/rest/client.go

@@ -42,7 +42,7 @@ type Client struct {
 }
 
 // Call - make a REST call.
-func (c *Client) Call(method string, values url.Values, body io.Reader) (reply io.ReadCloser, err error) {
+func (c *Client) Call(method string, values url.Values, body io.Reader, length int64) (reply io.ReadCloser, err error) {
 	req, err := http.NewRequest(http.MethodPost, c.url.String()+"/"+method+"?"+values.Encode(), body)
 	if err != nil {
 		return nil, err
@@ -50,7 +50,9 @@ func (c *Client) Call(method string, values url.Values, body io.Reader) (reply i
 
 	req.Header.Set("Authorization", "Bearer "+c.newAuthToken())
 	req.Header.Set("X-Minio-Time", time.Now().UTC().Format(time.RFC3339))
-
+	if length > 0 {
+		req.ContentLength = length
+	}
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
 		return nil, err

cmd/storage-errors.go

@@ -82,6 +82,9 @@ var errMinDiskSize = errors.New("The disk size is less than the minimum threshol
 // errLessData - returned when less data available than what was requested.
 var errLessData = errors.New("less data available than what was requested")
 
+// errMoreData = returned when more data was sent by the caller than what it was supposed to.
+var errMoreData = errors.New("more data was sent than what was advertised")
+
 // hashMisMatchError - represents a bit-rot hash verification failure
 // error.
 type hashMismatchError struct {

cmd/storage-interface.go

@@ -41,8 +41,9 @@ type StorageAPI interface {
 	// File operations.
 	ListDir(volume, dirPath string, count int) ([]string, error)
 	ReadFile(volume string, path string, offset int64, buf []byte, verifier *BitrotVerifier) (n int64, err error)
-	PrepareFile(volume string, path string, len int64) (err error)
 	AppendFile(volume string, path string, buf []byte) (err error)
+	CreateFile(volume, path string, size int64, reader io.Reader) error
+	ReadFileStream(volume, path string, offset, length int64) (io.ReadCloser, error)
 	RenameFile(srcVolume, srcPath, dstVolume, dstPath string) error
 	StatFile(volume string, path string) (file FileInfo, err error)
 	DeleteFile(volume string, path string) (err error)

cmd/storage-rest-client.go

@@ -115,11 +115,11 @@ type storageRESTClient struct {
 // Wrapper to restClient.Call to handle network errors, in case of network error the connection is makred disconnected
 // permanently. The only way to restore the storage connection is at the xl-sets layer by xlsets.monitorAndConnectEndpoints()
 // after verifying format.json
-func (client *storageRESTClient) call(method string, values url.Values, body io.Reader) (respBody io.ReadCloser, err error) {
+func (client *storageRESTClient) call(method string, values url.Values, body io.Reader, length int64) (respBody io.ReadCloser, err error) {
 	if !client.connected {
 		return nil, errDiskNotFound
 	}
-	respBody, err = client.restClient.Call(method, values, body)
+	respBody, err = client.restClient.Call(method, values, body, length)
 	if err == nil {
 		return respBody, nil
 	}
@@ -148,7 +148,7 @@ func (client *storageRESTClient) LastError() error {
 
 // DiskInfo - fetch disk information for a remote disk.
 func (client *storageRESTClient) DiskInfo() (info DiskInfo, err error) {
-	respBody, err := client.call(storageRESTMethodDiskInfo, nil, nil)
+	respBody, err := client.call(storageRESTMethodDiskInfo, nil, nil, -1)
 	if err != nil {
 		return
 	}
@@ -161,14 +161,14 @@ func (client *storageRESTClient) DiskInfo() (info DiskInfo, err error) {
 func (client *storageRESTClient) MakeVol(volume string) (err error) {
 	values := make(url.Values)
 	values.Set(storageRESTVolume, volume)
-	respBody, err := client.call(storageRESTMethodMakeVol, values, nil)
+	respBody, err := client.call(storageRESTMethodMakeVol, values, nil, -1)
 	defer CloseResponse(respBody)
 	return err
 }
 
 // ListVols - List all volumes on a remote disk.
 func (client *storageRESTClient) ListVols() (volinfo []VolInfo, err error) {
-	respBody, err := client.call(storageRESTMethodListVols, nil, nil)
+	respBody, err := client.call(storageRESTMethodListVols, nil, nil, -1)
 	if err != nil {
 		return
 	}
@@ -181,7 +181,7 @@ func (client *storageRESTClient) ListVols() (volinfo []VolInfo, err error) {
 func (client *storageRESTClient) StatVol(volume string) (volInfo VolInfo, err error) {
 	values := make(url.Values)
 	values.Set(storageRESTVolume, volume)
-	respBody, err := client.call(storageRESTMethodStatVol, values, nil)
+	respBody, err := client.call(storageRESTMethodStatVol, values, nil, -1)
 	if err != nil {
 		return
 	}
@@ -194,29 +194,28 @@ func (client *storageRESTClient) StatVol(volume string) (volInfo VolInfo, err er
 func (client *storageRESTClient) DeleteVol(volume string) (err error) {
 	values := make(url.Values)
 	values.Set(storageRESTVolume, volume)
-	respBody, err := client.call(storageRESTMethodDeleteVol, values, nil)
+	respBody, err := client.call(storageRESTMethodDeleteVol, values, nil, -1)
 	defer CloseResponse(respBody)
 	return err
 }
 
-// PrepareFile - to fallocate() disk space for a file.
+// AppendFile - append to a file.
-func (client *storageRESTClient) PrepareFile(volume, path string, length int64) error {
+func (client *storageRESTClient) AppendFile(volume, path string, buffer []byte) error {
 	values := make(url.Values)
 	values.Set(storageRESTVolume, volume)
 	values.Set(storageRESTFilePath, path)
-	values.Set(storageRESTLength, strconv.Itoa(int(length)))
+	reader := bytes.NewBuffer(buffer)
-	respBody, err := client.call(storageRESTMethodPrepareFile, values, nil)
+	respBody, err := client.call(storageRESTMethodAppendFile, values, reader, -1)
 	defer CloseResponse(respBody)
 	return err
 }
 
-// AppendFile - append to a file.
+func (client *storageRESTClient) CreateFile(volume, path string, length int64, r io.Reader) error {
-func (client *storageRESTClient) AppendFile(volume, path string, buffer []byte) error {
 	values := make(url.Values)
 	values.Set(storageRESTVolume, volume)
 	values.Set(storageRESTFilePath, path)
-	reader := bytes.NewBuffer(buffer)
+	values.Set(storageRESTLength, strconv.Itoa(int(length)))
-	respBody, err := client.call(storageRESTMethodAppendFile, values, reader)
+	respBody, err := client.call(storageRESTMethodCreateFile, values, r, length)
 	defer CloseResponse(respBody)
 	return err
 }
@@ -227,7 +226,7 @@ func (client *storageRESTClient) WriteAll(volume, path string, buffer []byte) er
 	values.Set(storageRESTVolume, volume)
 	values.Set(storageRESTFilePath, path)
 	reader := bytes.NewBuffer(buffer)
-	respBody, err := client.call(storageRESTMethodWriteAll, values, reader)
+	respBody, err := client.call(storageRESTMethodWriteAll, values, reader, -1)
 	defer CloseResponse(respBody)
 	return err
 }
@@ -237,7 +236,7 @@ func (client *storageRESTClient) StatFile(volume, path string) (info FileInfo, e
 	values := make(url.Values)
 	values.Set(storageRESTVolume, volume)
 	values.Set(storageRESTFilePath, path)
-	respBody, err := client.call(storageRESTMethodStatFile, values, nil)
+	respBody, err := client.call(storageRESTMethodStatFile, values, nil, -1)
 	if err != nil {
 		return info, err
 	}
@@ -251,7 +250,7 @@ func (client *storageRESTClient) ReadAll(volume, path string) ([]byte, error) {
 	values := make(url.Values)
 	values.Set(storageRESTVolume, volume)
 	values.Set(storageRESTFilePath, path)
-	respBody, err := client.call(storageRESTMethodReadAll, values, nil)
+	respBody, err := client.call(storageRESTMethodReadAll, values, nil, -1)
 	if err != nil {
 		return nil, err
 	}
@@ -259,6 +258,20 @@ func (client *storageRESTClient) ReadAll(volume, path string) ([]byte, error) {
 	return ioutil.ReadAll(respBody)
 }
 
+// ReadFileStream - returns a reader for the requested file.
+func (client *storageRESTClient) ReadFileStream(volume, path string, offset, length int64) (io.ReadCloser, error) {
+	values := make(url.Values)
+	values.Set(storageRESTVolume, volume)
+	values.Set(storageRESTFilePath, path)
+	values.Set(storageRESTOffset, strconv.Itoa(int(offset)))
+	values.Set(storageRESTLength, strconv.Itoa(int(length)))
+	respBody, err := client.call(storageRESTMethodReadFileStream, values, nil, -1)
+	if err != nil {
+		return nil, err
+	}
+	return respBody, nil
+}
+
 // ReadFile - reads section of a file.
 func (client *storageRESTClient) ReadFile(volume, path string, offset int64, buffer []byte, verifier *BitrotVerifier) (int64, error) {
 	values := make(url.Values)
@@ -273,7 +286,7 @@ func (client *storageRESTClient) ReadFile(volume, path string, offset int64, buf
 		values.Set(storageRESTBitrotAlgo, "")
 		values.Set(storageRESTBitrotHash, "")
 	}
-	respBody, err := client.call(storageRESTMethodReadFile, values, nil)
+	respBody, err := client.call(storageRESTMethodReadFile, values, nil, -1)
 	if err != nil {
 		return 0, err
 	}
@@ -288,7 +301,7 @@ func (client *storageRESTClient) ListDir(volume, dirPath string, count int) (ent
 	values.Set(storageRESTVolume, volume)
 	values.Set(storageRESTDirPath, dirPath)
 	values.Set(storageRESTCount, strconv.Itoa(count))
-	respBody, err := client.call(storageRESTMethodListDir, values, nil)
+	respBody, err := client.call(storageRESTMethodListDir, values, nil, -1)
 	if err != nil {
 		return nil, err
 	}
@@ -302,7 +315,7 @@ func (client *storageRESTClient) DeleteFile(volume, path string) error {
 	values := make(url.Values)
 	values.Set(storageRESTVolume, volume)
 	values.Set(storageRESTFilePath, path)
-	respBody, err := client.call(storageRESTMethodDeleteFile, values, nil)
+	respBody, err := client.call(storageRESTMethodDeleteFile, values, nil, -1)
 	defer CloseResponse(respBody)
 	return err
 }
@@ -314,7 +327,7 @@ func (client *storageRESTClient) RenameFile(srcVolume, srcPath, dstVolume, dstPa
 	values.Set(storageRESTSrcPath, srcPath)
 	values.Set(storageRESTDstVolume, dstVolume)
 	values.Set(storageRESTDstPath, dstPath)
-	respBody, err := client.call(storageRESTMethodRenameFile, values, nil)
+	respBody, err := client.call(storageRESTMethodRenameFile, values, nil, -1)
 	defer CloseResponse(respBody)
 	return err
 }

cmd/storage-rest-common.go

@@ -16,7 +16,7 @@
 
 package cmd
 
-const storageRESTVersion = "v2"
+const storageRESTVersion = "v3"
 const storageRESTPath = minioReservedBucketPath + "/storage/" + storageRESTVersion + "/"
 
 const (
@@ -26,15 +26,16 @@ const (
 	storageRESTMethodDeleteVol = "deletevol"
 	storageRESTMethodListVols  = "listvols"
 
-	storageRESTMethodPrepareFile = "preparefile"
+	storageRESTMethodAppendFile     = "appendfile"
-	storageRESTMethodAppendFile  = "appendfile"
+	storageRESTMethodCreateFile     = "createfile"
-	storageRESTMethodWriteAll    = "writeall"
+	storageRESTMethodWriteAll       = "writeall"
-	storageRESTMethodStatFile    = "statfile"
+	storageRESTMethodStatFile       = "statfile"
-	storageRESTMethodReadAll     = "readall"
+	storageRESTMethodReadAll        = "readall"
-	storageRESTMethodReadFile    = "readfile"
+	storageRESTMethodReadFile       = "readfile"
-	storageRESTMethodListDir     = "listdir"
+	storageRESTMethodReadFileStream = "readfilestream"
-	storageRESTMethodDeleteFile  = "deletefile"
+	storageRESTMethodListDir        = "listdir"
-	storageRESTMethodRenameFile  = "renamefile"
+	storageRESTMethodDeleteFile     = "deletefile"
+	storageRESTMethodRenameFile     = "renamefile"
 )
 
 const (

cmd/storage-rest-server.go

@@ -133,28 +133,29 @@ func (s *storageRESTServer) DeleteVolHandler(w http.ResponseWriter, r *http.Requ
 	}
 }
 
-// PrepareFileHandler - fallocate() space for a file.
+// AppendFileHandler - append data from the request to the file specified.
-func (s *storageRESTServer) PrepareFileHandler(w http.ResponseWriter, r *http.Request) {
+func (s *storageRESTServer) AppendFileHandler(w http.ResponseWriter, r *http.Request) {
 	if !s.IsValid(w, r) {
 		return
 	}
 	vars := mux.Vars(r)
 	volume := vars[storageRESTVolume]
 	filePath := vars[storageRESTFilePath]
-	fileSizeStr := vars[storageRESTLength]
+
-	fileSize, err := strconv.Atoi(fileSizeStr)
+	buf := make([]byte, r.ContentLength)
+	_, err := io.ReadFull(r.Body, buf)
 	if err != nil {
 		s.writeErrorResponse(w, err)
 		return
 	}
-	err = s.storage.PrepareFile(volume, filePath, int64(fileSize))
+	err = s.storage.AppendFile(volume, filePath, buf)
 	if err != nil {
 		s.writeErrorResponse(w, err)
 	}
 }
 
-// AppendFileHandler - append to a file.
+// CreateFileHandler - fallocate() space for a file and copy the contents from the request.
-func (s *storageRESTServer) AppendFileHandler(w http.ResponseWriter, r *http.Request) {
+func (s *storageRESTServer) CreateFileHandler(w http.ResponseWriter, r *http.Request) {
 	if !s.IsValid(w, r) {
 		return
 	}
@@ -162,18 +163,13 @@ func (s *storageRESTServer) AppendFileHandler(w http.ResponseWriter, r *http.Req
 	volume := vars[storageRESTVolume]
 	filePath := vars[storageRESTFilePath]
 
-	if r.ContentLength < 0 {
+	fileSizeStr := vars[storageRESTLength]
-		s.writeErrorResponse(w, errInvalidArgument)
+	fileSize, err := strconv.Atoi(fileSizeStr)
-		return
-	}
-
-	buf := make([]byte, r.ContentLength)
-	_, err := io.ReadFull(r.Body, buf)
 	if err != nil {
 		s.writeErrorResponse(w, err)
 		return
 	}
-	err = s.storage.AppendFile(volume, filePath, buf)
+	err = s.storage.CreateFile(volume, filePath, int64(fileSize), r.Body)
 	if err != nil {
 		s.writeErrorResponse(w, err)
 	}
@@ -285,6 +281,34 @@ func (s *storageRESTServer) ReadFileHandler(w http.ResponseWriter, r *http.Reque
 	w.Write(buf)
 }
 
+// ReadFileHandler - read section of a file.
+func (s *storageRESTServer) ReadFileStreamHandler(w http.ResponseWriter, r *http.Request) {
+	if !s.IsValid(w, r) {
+		return
+	}
+	vars := mux.Vars(r)
+	volume := vars[storageRESTVolume]
+	filePath := vars[storageRESTFilePath]
+	offset, err := strconv.Atoi(vars[storageRESTOffset])
+	if err != nil {
+		s.writeErrorResponse(w, err)
+		return
+	}
+	length, err := strconv.Atoi(vars[storageRESTLength])
+	if err != nil {
+		s.writeErrorResponse(w, err)
+		return
+	}
+	rc, err := s.storage.ReadFileStream(volume, filePath, int64(offset), int64(length))
+	if err != nil {
+		s.writeErrorResponse(w, err)
+		return
+	}
+	defer rc.Close()
+	w.Header().Set("Content-Length", strconv.Itoa(length))
+	io.Copy(w, rc)
+}
+
 // ListDirHandler - list a directory.
 func (s *storageRESTServer) ListDirHandler(w http.ResponseWriter, r *http.Request) {
 	if !s.IsValid(w, r) {
@@ -359,18 +383,21 @@ func registerStorageRESTHandlers(router *mux.Router, endpoints EndpointList) {
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodDeleteVol).HandlerFunc(httpTraceHdrs(server.DeleteVolHandler)).Queries(restQueries(storageRESTVolume)...)
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodListVols).HandlerFunc(httpTraceHdrs(server.ListVolsHandler))
 
-		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodPrepareFile).HandlerFunc(httpTraceHdrs(server.PrepareFileHandler)).
-			Queries(restQueries(storageRESTVolume, storageRESTFilePath, storageRESTLength)...)
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodAppendFile).HandlerFunc(httpTraceHdrs(server.AppendFileHandler)).
 			Queries(restQueries(storageRESTVolume, storageRESTFilePath)...)
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodWriteAll).HandlerFunc(httpTraceHdrs(server.WriteAllHandler)).
 			Queries(restQueries(storageRESTVolume, storageRESTFilePath)...)
+		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodCreateFile).HandlerFunc(httpTraceHdrs(server.CreateFileHandler)).
+			Queries(restQueries(storageRESTVolume, storageRESTFilePath, storageRESTLength)...)
+
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodStatFile).HandlerFunc(httpTraceHdrs(server.StatFileHandler)).
 			Queries(restQueries(storageRESTVolume, storageRESTFilePath)...)
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodReadAll).HandlerFunc(httpTraceHdrs(server.ReadAllHandler)).
 			Queries(restQueries(storageRESTVolume, storageRESTFilePath)...)
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodReadFile).HandlerFunc(httpTraceHdrs(server.ReadFileHandler)).
 			Queries(restQueries(storageRESTVolume, storageRESTFilePath, storageRESTOffset, storageRESTLength, storageRESTBitrotAlgo, storageRESTBitrotHash)...)
+		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodReadFileStream).HandlerFunc(httpTraceHdrs(server.ReadFileStreamHandler)).
+			Queries(restQueries(storageRESTVolume, storageRESTFilePath, storageRESTOffset, storageRESTLength)...)
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodListDir).HandlerFunc(httpTraceHdrs(server.ListDirHandler)).
 			Queries(restQueries(storageRESTVolume, storageRESTDirPath, storageRESTCount)...)
 		subrouter.Methods(http.MethodPost).Path("/" + storageRESTMethodDeleteFile).HandlerFunc(httpTraceHdrs(server.DeleteFileHandler)).

cmd/storage-rest_test.go

@@ -365,38 +365,6 @@ func testStorageAPIReadFile(t *testing.T, storage StorageAPI) {
 	}
 }
 
-func testStorageAPIPrepareFile(t *testing.T, storage StorageAPI) {
-	tmpGlobalServerConfig := globalServerConfig
-	defer func() {
-		globalServerConfig = tmpGlobalServerConfig
-	}()
-	globalServerConfig = newServerConfig()
-
-	err := storage.MakeVol("foo")
-	if err != nil {
-		t.Fatalf("unexpected error %v", err)
-	}
-
-	testCases := []struct {
-		volumeName string
-		objectName string
-		expectErr  bool
-	}{
-		{"foo", "myobject", false},
-		// volume not found error.
-		{"bar", "myobject", true},
-	}
-
-	for i, testCase := range testCases {
-		err := storage.PrepareFile(testCase.volumeName, testCase.objectName, 1)
-		expectErr := (err != nil)
-
-		if expectErr != testCase.expectErr {
-			t.Fatalf("case %v: error: expected: %v, got: %v", i+1, testCase.expectErr, expectErr)
-		}
-	}
-}
-
 func testStorageAPIAppendFile(t *testing.T, storage StorageAPI) {
 	tmpGlobalServerConfig := globalServerConfig
 	defer func() {
@@ -648,17 +616,6 @@ func TestStorageRESTClientReadFile(t *testing.T) {
 	testStorageAPIReadFile(t, restClient)
 }
 
-func TestStorageRESTClientPrepareFile(t *testing.T) {
-	httpServer, restClient, prevGlobalServerConfig, endpointPath := newStorageRESTHTTPServerClient(t)
-	defer httpServer.Close()
-	defer func() {
-		globalServerConfig = prevGlobalServerConfig
-	}()
-	defer os.RemoveAll(endpointPath)
-
-	testStorageAPIPrepareFile(t, restClient)
-}
-
 func TestStorageRESTClientAppendFile(t *testing.T) {
 	httpServer, restClient, prevGlobalServerConfig, endpointPath := newStorageRESTHTTPServerClient(t)
 	defer httpServer.Close()

cmd/test-utils_test.go

@@ -77,7 +77,8 @@ func init() {
 	// Set system resources to maximum.
 	setMaxResources()
 
-	logger.Disable = true
+	// Uncomment the following line to see trace logs during unit tests.
+	// logger.AddTarget(console.New())
 }
 
 // concurreny level for certain parallel tests.

cmd/xl-v1-healing-common.go

@@ -18,7 +18,6 @@ package cmd
 
 import (
 	"context"
-	"path/filepath"
 	"strings"
 	"time"
 
@@ -161,7 +160,6 @@ func getLatestXLMeta(ctx context.Context, partsMetadata []xlMetaV1, errs []error
 func disksWithAllParts(ctx context.Context, onlineDisks []StorageAPI, partsMetadata []xlMetaV1, errs []error, bucket,
 	object string) ([]StorageAPI, []error) {
 	availableDisks := make([]StorageAPI, len(onlineDisks))
-	buffer := []byte{}
 	dataErrs := make([]error, len(onlineDisks))
 
 	for i, onlineDisk := range onlineDisks {
@@ -170,31 +168,26 @@ func disksWithAllParts(ctx context.Context, onlineDisks []StorageAPI, partsMetad
 			continue
 		}
 
+		erasureInfo := partsMetadata[i].Erasure
+		erasure, err := NewErasure(ctx, erasureInfo.DataBlocks, erasureInfo.ParityBlocks, erasureInfo.BlockSize)
+		if err != nil {
+			dataErrs[i] = err
+			continue
+		}
+
 		// disk has a valid xl.json but may not have all the
 		// parts. This is considered an outdated disk, since
 		// it needs healing too.
 		for _, part := range partsMetadata[i].Parts {
-			partPath := filepath.Join(object, part.Name)
+			checksumInfo := erasureInfo.GetChecksumInfo(part.Name)
-			checksumInfo := partsMetadata[i].Erasure.GetChecksumInfo(part.Name)
+			tillOffset := erasure.ShardFileTillOffset(0, part.Size, part.Size)
-			verifier := NewBitrotVerifier(checksumInfo.Algorithm, checksumInfo.Hash)
+			err = bitrotCheckFile(onlineDisk, bucket, pathJoin(object, part.Name), tillOffset, checksumInfo.Algorithm, checksumInfo.Hash, erasure.ShardSize())
-
+			if err != nil {
-			// verification happens even if a 0-length
+				isCorrupt := strings.HasPrefix(err.Error(), "Bitrot verification mismatch - expected ")
-			// buffer is passed
+				if !isCorrupt && err != errFileNotFound && err != errVolumeNotFound {
-			_, hErr := onlineDisk.ReadFile(bucket, partPath, 0, buffer, verifier)
+					logger.LogIf(ctx, err)
-
+				}
-			isCorrupt := false
+				dataErrs[i] = err
-			if hErr != nil {
-				isCorrupt = strings.HasPrefix(hErr.Error(), "Bitrot verification mismatch - expected ")
-			}
-			switch {
-			case isCorrupt:
-				fallthrough
-			case hErr == errFileNotFound, hErr == errVolumeNotFound:
-				dataErrs[i] = hErr
-				break
-			case hErr != nil:
-				logger.LogIf(ctx, hErr)
-				dataErrs[i] = hErr
 				break
 			}
 		}

cmd/xl-v1-healing-common_test.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"bytes"
 	"context"
+	"os"
 	"path/filepath"
 	"testing"
 	"time"
@@ -85,28 +86,6 @@ func TestCommonTime(t *testing.T) {
 	}
 }
 
-// partsMetaFromModTimes - returns slice of modTimes given metadata of
-// an object part.
-func partsMetaFromModTimes(modTimes []time.Time, algorithm BitrotAlgorithm, checksums []ChecksumInfo) []xlMetaV1 {
-	var partsMetadata []xlMetaV1
-	for _, modTime := range modTimes {
-		partsMetadata = append(partsMetadata, xlMetaV1{
-			Erasure: ErasureInfo{
-				Checksums: checksums,
-			},
-			Stat: statInfo{
-				ModTime: modTime,
-			},
-			Parts: []ObjectPartInfo{
-				{
-					Name: "part.1",
-				},
-			},
-		})
-	}
-	return partsMetadata
-}
-
 // TestListOnlineDisks - checks if listOnlineDisks and outDatedDisks
 // are consistent with each other.
 func TestListOnlineDisks(t *testing.T) {
@@ -205,12 +184,6 @@ func TestListOnlineDisks(t *testing.T) {
 			t.Fatalf("Failed to putObject %v", err)
 		}
 
-		// Fetch xl.json from first disk to construct partsMetadata for the tests.
-		xlMeta, err := readXLMeta(context.Background(), xlDisks[0], bucket, object)
-		if err != nil {
-			t.Fatalf("Test %d: Failed to read xl.json %v", i+1, err)
-		}
-
 		tamperedIndex := -1
 		switch test._tamperBackend {
 		case deletePart:
@@ -240,17 +213,25 @@ func TestListOnlineDisks(t *testing.T) {
 				// and check if that disk
 				// appears in outDatedDisks.
 				tamperedIndex = index
-				dErr := xlDisks[index].AppendFile(bucket, filepath.Join(object, "part.1"), []byte("corruption"))
+				filePath := pathJoin(xlDisks[index].String(), bucket, object, "part.1")
-				if dErr != nil {
+				f, err := os.OpenFile(filePath, os.O_WRONLY, 0)
-					t.Fatalf("Test %d: Failed to append corrupting data at the end of file %s - %v",
+				if err != nil {
-						i+1, filepath.Join(object, "part.1"), dErr)
+					t.Fatalf("Failed to open %s: %s\n", filePath, err)
 				}
+				f.Write([]byte("oops")) // Will cause bitrot error
+				f.Close()
 				break
 			}
 
 		}
 
-		partsMetadata := partsMetaFromModTimes(test.modTimes, DefaultBitrotAlgorithm, xlMeta.Erasure.Checksums)
+		partsMetadata, errs := readAllXLMetadata(context.Background(), xlDisks, bucket, object)
+		for i := range partsMetadata {
+			if errs[i] != nil {
+				t.Fatalf("Test %d: expected error to be nil: %s", i+1, errs[i].Error())
+			}
+			partsMetadata[i].Stat.ModTime = test.modTimes[i]
+		}
 
 		onlineDisks, modTime := listOnlineDisks(xlDisks, partsMetadata, test.errs)
 		if !modTime.Equal(test.expectedTime) {
@@ -303,6 +284,29 @@ func TestDisksWithAllParts(t *testing.T) {
 		t.Fatalf("Failed to read xl meta data %v", reducedErr)
 	}
 
+	// Test that all disks are returned without any failures with
+	// unmodified meta data
+	partsMetadata, errs = readAllXLMetadata(ctx, xlDisks, bucket, object)
+	if err != nil {
+		t.Fatalf("Failed to read xl meta data %v", err)
+	}
+
+	filteredDisks, errs := disksWithAllParts(ctx, xlDisks, partsMetadata, errs, bucket, object)
+
+	if len(filteredDisks) != len(xlDisks) {
+		t.Errorf("Unexpected number of disks: %d", len(filteredDisks))
+	}
+
+	for diskIndex, disk := range filteredDisks {
+		if errs[diskIndex] != nil {
+			t.Errorf("Unexpected error %s", errs[diskIndex])
+		}
+
+		if disk == nil {
+			t.Errorf("Disk erroneously filtered, diskIndex: %d", diskIndex)
+		}
+	}
+
 	diskFailures := make(map[int]string)
 	// key = disk index, value = part name with hash mismatch
 	diskFailures[0] = "part.3"
@@ -310,15 +314,21 @@ func TestDisksWithAllParts(t *testing.T) {
 	diskFailures[15] = "part.2"
 
 	for diskIndex, partName := range diskFailures {
-		for index, info := range partsMetadata[diskIndex].Erasure.Checksums {
+		for _, info := range partsMetadata[diskIndex].Erasure.Checksums {
 			if info.Name == partName {
-				partsMetadata[diskIndex].Erasure.Checksums[index].Hash[0]++
+				filePath := pathJoin(xlDisks[diskIndex].String(), bucket, object, partName)
+				f, err := os.OpenFile(filePath, os.O_WRONLY, 0)
+				if err != nil {
+					t.Fatalf("Failed to open %s: %s\n", filePath, err)
+				}
+				f.Write([]byte("oops")) // Will cause bitrot error
+				f.Close()
 			}
 		}
 	}
 
 	errs = make([]error, len(xlDisks))
-	filteredDisks, errs := disksWithAllParts(ctx, xlDisks, partsMetadata, errs, bucket, object)
+	filteredDisks, errs = disksWithAllParts(ctx, xlDisks, partsMetadata, errs, bucket, object)
 
 	if len(filteredDisks) != len(xlDisks) {
 		t.Errorf("Unexpected number of disks: %d", len(filteredDisks))
@@ -343,27 +353,4 @@ func TestDisksWithAllParts(t *testing.T) {
 		}
 	}
 
-	// Test that all disks are returned without any failures with
-	// unmodified meta data
-	partsMetadata, errs = readAllXLMetadata(ctx, xlDisks, bucket, object)
-	if err != nil {
-		t.Fatalf("Failed to read xl meta data %v", err)
-	}
-
-	filteredDisks, errs = disksWithAllParts(ctx, xlDisks, partsMetadata, errs, bucket, object)
-
-	if len(filteredDisks) != len(xlDisks) {
-		t.Errorf("Unexpected number of disks: %d", len(filteredDisks))
-	}
-
-	for diskIndex, disk := range filteredDisks {
-		if errs[diskIndex] != nil {
-			t.Errorf("Unexpected error %s", errs[diskIndex])
-		}
-
-		if disk == nil {
-			t.Errorf("Disk erroneously filtered, diskIndex: %d", diskIndex)
-		}
-	}
-
 }

cmd/xl-v1-healing.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"context"
 	"fmt"
+	"io"
 	"path"
 	"sync"
 
@@ -405,15 +406,16 @@ func healObject(ctx context.Context, storageDisks []StorageAPI, bucket string, o
 	latestDisks = shuffleDisks(latestDisks, latestMeta.Erasure.Distribution)
 	outDatedDisks = shuffleDisks(outDatedDisks, latestMeta.Erasure.Distribution)
 	partsMetadata = shufflePartsMetadata(partsMetadata, latestMeta.Erasure.Distribution)
+	for i := range outDatedDisks {
+		if outDatedDisks[i] == nil {
+			continue
+		}
+		partsMetadata[i] = newXLMetaFromXLMeta(latestMeta)
+	}
 
 	// We write at temporary location and then rename to final location.
 	tmpID := mustGetUUID()
 
-	// Checksum of the part files. checkSumInfos[index] will
-	// contain checksums of all the part files in the
-	// outDatedDisks[index]
-	checksumInfos := make([][]ChecksumInfo, len(outDatedDisks))
-
 	// Heal each part. erasureHealFile() will write the healed
 	// part to .minio/tmp/uuid/ which needs to be renamed later to
 	// the final location.
@@ -423,29 +425,31 @@ func healObject(ctx context.Context, storageDisks []StorageAPI, bucket string, o
 		return result, toObjectErr(err, bucket, object)
 	}
 
+	erasureInfo := latestMeta.Erasure
 	for partIndex := 0; partIndex < len(latestMeta.Parts); partIndex++ {
 		partName := latestMeta.Parts[partIndex].Name
 		partSize := latestMeta.Parts[partIndex].Size
-		erasureInfo := latestMeta.Erasure
+		partActualSize := latestMeta.Parts[partIndex].ActualSize
-		var algorithm BitrotAlgorithm
+		partNumber := latestMeta.Parts[partIndex].Number
-		bitrotReaders := make([]*bitrotReader, len(latestDisks))
+		tillOffset := erasure.ShardFileTillOffset(0, partSize, partSize)
+		checksumInfo := erasureInfo.GetChecksumInfo(partName)
+		readers := make([]io.ReaderAt, len(latestDisks))
 		for i, disk := range latestDisks {
 			if disk == OfflineDisk {
 				continue
 			}
-			info := partsMetadata[i].Erasure.GetChecksumInfo(partName)
+			readers[i] = newBitrotReader(disk, bucket, pathJoin(object, partName), tillOffset, checksumInfo.Algorithm, checksumInfo.Hash, erasure.ShardSize())
-			algorithm = info.Algorithm
-			endOffset := getErasureShardFileEndOffset(0, partSize, partSize, erasureInfo.BlockSize, erasure.dataBlocks)
-			bitrotReaders[i] = newBitrotReader(disk, bucket, pathJoin(object, partName), algorithm, endOffset, info.Hash)
 		}
-		bitrotWriters := make([]*bitrotWriter, len(outDatedDisks))
+		writers := make([]io.Writer, len(outDatedDisks))
 		for i, disk := range outDatedDisks {
 			if disk == OfflineDisk {
 				continue
 			}
-			bitrotWriters[i] = newBitrotWriter(disk, minioMetaTmpBucket, pathJoin(tmpID, partName), algorithm)
+			writers[i] = newBitrotWriter(disk, minioMetaTmpBucket, pathJoin(tmpID, partName), tillOffset, checksumInfo.Algorithm, erasure.ShardSize())
 		}
-		hErr := erasure.Heal(ctx, bitrotReaders, bitrotWriters, partSize)
+		hErr := erasure.Heal(ctx, readers, writers, partSize)
+		closeBitrotReaders(readers)
+		closeBitrotWriters(writers)
 		if hErr != nil {
 			return result, toObjectErr(hErr, bucket, object)
 		}
@@ -457,14 +461,13 @@ func healObject(ctx context.Context, storageDisks []StorageAPI, bucket string, o
 			}
 			// A non-nil stale disk which did not receive
 			// a healed part checksum had a write error.
-			if bitrotWriters[i] == nil {
+			if writers[i] == nil {
 				outDatedDisks[i] = nil
 				disksToHealCount--
 				continue
 			}
-			// append part checksums
+			partsMetadata[i].AddObjectPart(partNumber, partName, "", partSize, partActualSize)
-			checksumInfos[i] = append(checksumInfos[i],
+			partsMetadata[i].Erasure.AddChecksumInfo(ChecksumInfo{partName, checksumInfo.Algorithm, bitrotWriterSum(writers[i])})
-				ChecksumInfo{partName, algorithm, bitrotWriters[i].Sum()})
 		}
 
 		// If all disks are having errors, we give up.
@@ -479,7 +482,6 @@ func healObject(ctx context.Context, storageDisks []StorageAPI, bucket string, o
 			continue
 		}
 		partsMetadata[index] = latestMeta
-		partsMetadata[index].Erasure.Checksums = checksumInfos[index]
 	}
 
 	// Generate and write `xl.json` generated from other disks.

cmd/xl-v1-metadata.go

@@ -58,7 +58,7 @@ type ChecksumInfo struct {
 type checksumInfoJSON struct {
 	Name      string `json:"name"`
 	Algorithm string `json:"algorithm"`
-	Hash      string `json:"hash"`
+	Hash      string `json:"hash,omitempty"`
 }
 
 // MarshalJSON marshals the ChecksumInfo struct
@@ -186,6 +186,23 @@ func newXLMetaV1(object string, dataBlocks, parityBlocks int) (xlMeta xlMetaV1)
 	return xlMeta
 }
 
+// Return a new xlMetaV1 initialized using the given xlMetaV1. Used in healing to make sure that we do not copy
+// over any part's checksum info which will differ for different disks.
+func newXLMetaFromXLMeta(meta xlMetaV1) xlMetaV1 {
+	xlMeta := xlMetaV1{}
+	xlMeta.Version = xlMetaVersion
+	xlMeta.Format = xlMetaFormat
+	xlMeta.Minio.Release = ReleaseTag
+	xlMeta.Erasure = ErasureInfo{
+		Algorithm:    meta.Erasure.Algorithm,
+		DataBlocks:   meta.Erasure.DataBlocks,
+		ParityBlocks: meta.Erasure.DataBlocks,
+		BlockSize:    meta.Erasure.BlockSize,
+		Distribution: meta.Erasure.Distribution,
+	}
+	return xlMeta
+}
+
 // IsValid - tells if the format is sane by validating the version
 // string, format and erasure info fields.
 func (m xlMetaV1) IsValid() bool {

cmd/xl-v1-multipart.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"context"
 	"fmt"
+	"io"
 	"path"
 	"sort"
 	"strconv"
@@ -351,14 +352,6 @@ func (xl xlObjects) PutObjectPart(ctx context.Context, bucket, object, uploadID
 	// Delete the temporary object part. If PutObjectPart succeeds there would be nothing to delete.
 	defer xl.deleteObject(ctx, minioMetaTmpBucket, tmpPart, writeQuorum, false)
 
-	if data.Size() >= 0 {
-		if pErr := xl.prepareFile(ctx, minioMetaTmpBucket, tmpPartPath, data.Size(),
-			onlineDisks, xlMeta.Erasure.BlockSize, xlMeta.Erasure.DataBlocks, writeQuorum); pErr != nil {
-			return pi, toObjectErr(pErr, bucket, object)
-
-		}
-	}
-
 	erasure, err := NewErasure(ctx, xlMeta.Erasure.DataBlocks, xlMeta.Erasure.ParityBlocks, xlMeta.Erasure.BlockSize)
 	if err != nil {
 		return pi, toObjectErr(err, bucket, object)
@@ -380,16 +373,16 @@ func (xl xlObjects) PutObjectPart(ctx context.Context, bucket, object, uploadID
 	if len(buffer) > int(xlMeta.Erasure.BlockSize) {
 		buffer = buffer[:xlMeta.Erasure.BlockSize]
 	}
-
+	writers := make([]io.Writer, len(onlineDisks))
-	writers := make([]*bitrotWriter, len(onlineDisks))
 	for i, disk := range onlineDisks {
 		if disk == nil {
 			continue
 		}
-		writers[i] = newBitrotWriter(disk, minioMetaTmpBucket, tmpPartPath, DefaultBitrotAlgorithm)
+		writers[i] = newBitrotWriter(disk, minioMetaTmpBucket, tmpPartPath, erasure.ShardFileSize(data.Size()), DefaultBitrotAlgorithm, erasure.ShardSize())
 	}
 
 	n, err := erasure.Encode(ctx, data, writers, buffer, erasure.dataBlocks+1)
+	closeBitrotWriters(writers)
 	if err != nil {
 		return pi, toObjectErr(err, bucket, object)
 	}
@@ -455,7 +448,7 @@ func (xl xlObjects) PutObjectPart(ctx context.Context, bucket, object, uploadID
 		}
 		partsMetadata[i].Stat = xlMeta.Stat
 		partsMetadata[i].Parts = xlMeta.Parts
-		partsMetadata[i].Erasure.AddChecksumInfo(ChecksumInfo{partSuffix, DefaultBitrotAlgorithm, writers[i].Sum()})
+		partsMetadata[i].Erasure.AddChecksumInfo(ChecksumInfo{partSuffix, DefaultBitrotAlgorithm, bitrotWriterSum(writers[i])})
 	}
 
 	// Write all the checksum metadata.

cmd/xl-v1-object.go

@@ -57,25 +57,6 @@ func (xl xlObjects) putObjectDir(ctx context.Context, bucket, object string, wri
 	return reduceWriteQuorumErrs(ctx, errs, objectOpIgnoredErrs, writeQuorum)
 }
 
-// prepareFile hints the bottom layer to optimize the creation of a new object
-func (xl xlObjects) prepareFile(ctx context.Context, bucket, object string, size int64, onlineDisks []StorageAPI, blockSize int64, dataBlocks, writeQuorum int) error {
-	pErrs := make([]error, len(onlineDisks))
-	// Calculate the real size of the part in one disk.
-	actualSize := getErasureShardFileSize(blockSize, size, dataBlocks)
-	// Prepare object creation in a all disks
-	for index, disk := range onlineDisks {
-		if disk != nil {
-			if err := disk.PrepareFile(bucket, object, actualSize); err != nil {
-				// Save error to reduce it later
-				pErrs[index] = err
-				// Ignore later access to disk which generated the error
-				onlineDisks[index] = nil
-			}
-		}
-	}
-	return reduceWriteQuorumErrs(ctx, pErrs, objectOpIgnoredErrs, writeQuorum)
-}
-
 /// Object Operations
 
 // CopyObject - copy object source object to destination object.
@@ -348,22 +329,24 @@ func (xl xlObjects) getObject(ctx context.Context, bucket, object string, startO
 			partLength = length - totalBytesRead
 		}
 
+		tillOffset := erasure.ShardFileTillOffset(partOffset, partLength, partSize)
 		// Get the checksums of the current part.
-		bitrotReaders := make([]*bitrotReader, len(onlineDisks))
+		readers := make([]io.ReaderAt, len(onlineDisks))
 		for index, disk := range onlineDisks {
 			if disk == OfflineDisk {
 				continue
 			}
 			checksumInfo := metaArr[index].Erasure.GetChecksumInfo(partName)
-			endOffset := getErasureShardFileEndOffset(partOffset, partLength, partSize, xlMeta.Erasure.BlockSize, xlMeta.Erasure.DataBlocks)
+			readers[index] = newBitrotReader(disk, bucket, pathJoin(object, partName), tillOffset, checksumInfo.Algorithm, checksumInfo.Hash, erasure.ShardSize())
-			bitrotReaders[index] = newBitrotReader(disk, bucket, pathJoin(object, partName), checksumInfo.Algorithm, endOffset, checksumInfo.Hash)
 		}
-
+		err := erasure.Decode(ctx, writer, readers, partOffset, partLength, partSize)
-		err := erasure.Decode(ctx, writer, bitrotReaders, partOffset, partLength, partSize)
+		// Note: we should not be defer'ing the following closeBitrotReaders() call as we are inside a for loop i.e if we use defer, we would accumulate a lot of open files by the time
+		// we return from this function.
+		closeBitrotReaders(readers)
 		if err != nil {
 			return toObjectErr(err, bucket, object)
 		}
-		for i, r := range bitrotReaders {
+		for i, r := range readers {
 			if r == nil {
 				onlineDisks[i] = OfflineDisk
 			}
@@ -681,7 +664,6 @@ func (xl xlObjects) putObject(ctx context.Context, bucket string, object string,
 
 	uniqueID := mustGetUUID()
 	tempObj := uniqueID
-
 	// No metadata is set, allocate a new one.
 	if metadata == nil {
 		metadata = make(map[string]string)
@@ -793,6 +775,7 @@ func (xl xlObjects) putObject(ctx context.Context, bucket string, object string,
 		var curPartSize int64
 		curPartSize, err = calculatePartSizeFromIdx(ctx, data.Size(), globalPutPartSize, partIdx)
 		if err != nil {
+			logger.LogIf(ctx, err)
 			return ObjectInfo{}, toObjectErr(err, bucket, object)
 		}
 
@@ -800,27 +783,24 @@ func (xl xlObjects) putObject(ctx context.Context, bucket string, object string,
 		// This is only an optimization.
 		var curPartReader io.Reader
 
-		if curPartSize >= 0 {
-			pErr := xl.prepareFile(ctx, minioMetaTmpBucket, tempErasureObj, curPartSize, onlineDisks, xlMeta.Erasure.BlockSize, xlMeta.Erasure.DataBlocks, writeQuorum)
-			if pErr != nil {
-				return ObjectInfo{}, toObjectErr(pErr, bucket, object)
-			}
-		}
-
 		if curPartSize < data.Size() {
 			curPartReader = io.LimitReader(reader, curPartSize)
 		} else {
 			curPartReader = reader
 		}
 
-		writers := make([]*bitrotWriter, len(onlineDisks))
+		writers := make([]io.Writer, len(onlineDisks))
 		for i, disk := range onlineDisks {
 			if disk == nil {
 				continue
 			}
-			writers[i] = newBitrotWriter(disk, minioMetaTmpBucket, tempErasureObj, DefaultBitrotAlgorithm)
+			writers[i] = newBitrotWriter(disk, minioMetaTmpBucket, tempErasureObj, erasure.ShardFileSize(curPartSize), DefaultBitrotAlgorithm, erasure.ShardSize())
 		}
+
 		n, erasureErr := erasure.Encode(ctx, curPartReader, writers, buffer, erasure.dataBlocks+1)
+		// Note: we should not be defer'ing the following closeBitrotWriters() call as we are inside a for loop i.e if we use defer, we would accumulate a lot of open files by the time
+		// we return from this function.
+		closeBitrotWriters(writers)
 		if erasureErr != nil {
 			return ObjectInfo{}, toObjectErr(erasureErr, minioMetaTmpBucket, tempErasureObj)
 		}
@@ -853,7 +833,7 @@ func (xl xlObjects) putObject(ctx context.Context, bucket string, object string,
 				continue
 			}
 			partsMetadata[i].AddObjectPart(partIdx, partName, "", n, data.ActualSize())
-			partsMetadata[i].Erasure.AddChecksumInfo(ChecksumInfo{partName, DefaultBitrotAlgorithm, w.Sum()})
+			partsMetadata[i].Erasure.AddChecksumInfo(ChecksumInfo{partName, DefaultBitrotAlgorithm, bitrotWriterSum(w)})
 		}
 
 		// We wrote everything, break out.