XL: Fix GetObject erasure decode issues. (#1793)

erasure-readfile.go

@@ -16,114 +16,83 @@
 
 package main
 
-import (
-	"bytes"
-	"errors"
-	"io"
-)
+import "errors"
 
 // ReadFile - decoded erasure coded file.
-func (e erasure) ReadFile(volume, path string, startOffset int64, totalSize int64) (io.Reader, error) {
-	var totalLeft = totalSize
-	var bufWriter = new(bytes.Buffer)
-	for totalLeft > 0 {
-		// Figure out the right blockSize as it was encoded before.
-		var curBlockSize int64
-		if erasureBlockSize < totalLeft {
-			curBlockSize = erasureBlockSize
-		} else {
-			curBlockSize = totalLeft
-		}
-
-		// Calculate the current encoded block size.
-		curEncBlockSize := getEncodedBlockLen(curBlockSize, e.DataBlocks)
+func (e erasure) ReadFile(volume, path string, bufferOffset int64, startOffset int64, buffer []byte) (int64, error) {
+	// Calculate the current encoded block size.
+	curEncBlockSize := getEncodedBlockLen(int64(len(buffer)), e.DataBlocks)
+	offsetEncOffset := getEncodedBlockLen(startOffset, e.DataBlocks)
 
-		// Allocate encoded blocks up to storage disks.
-		enBlocks := make([][]byte, len(e.storageDisks))
+	// Allocate encoded blocks up to storage disks.
+	enBlocks := make([][]byte, len(e.storageDisks))
 
-		// Counter to keep success data blocks.
-		var successDataBlocksCount = 0
-		var noReconstruct bool // Set for no reconstruction.
+	// Counter to keep success data blocks.
+	var successDataBlocksCount = 0
+	var noReconstruct bool // Set for no reconstruction.
 
-		// Read from all the disks.
-		for index, disk := range e.storageDisks {
-			blockIndex := e.distribution[index] - 1
-			// Initialize shard slice and fill the data from each parts.
-			enBlocks[blockIndex] = make([]byte, curEncBlockSize)
-			if disk == nil {
-				enBlocks[blockIndex] = nil
-			} else {
-				var offset = int64(0)
-				// Read the necessary blocks.
-				_, err := disk.ReadFile(volume, path, offset, enBlocks[blockIndex])
-				if err != nil {
-					enBlocks[blockIndex] = nil
-				}
-			}
-			// Verify if we have successfully read all the data blocks.
-			if blockIndex < e.DataBlocks && enBlocks[blockIndex] != nil {
-				successDataBlocksCount++
-				// Set when we have all the data blocks and no
-				// reconstruction is needed, so that we can avoid
-				// erasure reconstruction.
-				noReconstruct = successDataBlocksCount == e.DataBlocks
-				if noReconstruct {
-					// Break out we have read all the data blocks.
-					break
-				}
-			}
+	// Read from all the disks.
+	for index, disk := range e.storageDisks {
+		blockIndex := e.distribution[index] - 1
+		// Initialize shard slice and fill the data from each parts.
+		enBlocks[blockIndex] = make([]byte, curEncBlockSize)
+		if disk == nil {
+			enBlocks[blockIndex] = nil
+			continue
 		}
-
-		// Check blocks if they are all zero in length, we have corruption return error.
-		if checkBlockSize(enBlocks) == 0 {
-			return nil, errDataCorrupt
+		// Read the necessary blocks.
+		_, err := disk.ReadFile(volume, path, offsetEncOffset, enBlocks[blockIndex])
+		if err != nil {
+			enBlocks[blockIndex] = nil
 		}
-
-		// Verify if reconstruction is needed, proceed with reconstruction.
-		if !noReconstruct {
-			err := e.ReedSolomon.Reconstruct(enBlocks)
-			if err != nil {
-				return nil, err
-			}
-			// Verify reconstructed blocks (parity).
-			ok, err := e.ReedSolomon.Verify(enBlocks)
-			if err != nil {
-				return nil, err
-			}
-			if !ok {
-				// Blocks cannot be reconstructed, corrupted data.
-				err = errors.New("Verification failed after reconstruction, data likely corrupted.")
-				return nil, err
+		// Verify if we have successfully read all the data blocks.
+		if blockIndex < e.DataBlocks && enBlocks[blockIndex] != nil {
+			successDataBlocksCount++
+			// Set when we have all the data blocks and no
+			// reconstruction is needed, so that we can avoid
+			// erasure reconstruction.
+			noReconstruct = successDataBlocksCount == e.DataBlocks
+			if noReconstruct {
+				// Break out we have read all the data blocks.
+				break
 			}
 		}
+	}
 
-		// Get data blocks from encoded blocks.
-		dataBlocks := getDataBlocks(enBlocks, e.DataBlocks, int(curBlockSize))
+	// Check blocks if they are all zero in length, we have corruption return error.
+	if checkBlockSize(enBlocks) == 0 {
+		return 0, errDataCorrupt
+	}
 
-		// Verify if the offset is right for the block, if not move to
-		// the next block.
-		if startOffset > 0 {
-			startOffset = startOffset - int64(len(dataBlocks))
-			// Start offset is greater than or equal to zero, skip the dataBlocks.
-			if startOffset >= 0 {
-				totalLeft = totalLeft - erasureBlockSize
-				continue
-			}
-			// Now get back the remaining offset if startOffset is negative.
-			startOffset = startOffset + int64(len(dataBlocks))
+	// Verify if reconstruction is needed, proceed with reconstruction.
+	if !noReconstruct {
+		err := e.ReedSolomon.Reconstruct(enBlocks)
+		if err != nil {
+			return 0, err
 		}
-
-		// Copy data blocks.
-		_, err := bufWriter.Write(dataBlocks[startOffset:])
+		// Verify reconstructed blocks (parity).
+		ok, err := e.ReedSolomon.Verify(enBlocks)
 		if err != nil {
-			return nil, err
+			return 0, err
 		}
+		if !ok {
+			// Blocks cannot be reconstructed, corrupted data.
+			err = errors.New("Verification failed after reconstruction, data likely corrupted.")
+			return 0, err
+		}
+	}
 
-		// Reset dataBlocks to relenquish memory.
-		dataBlocks = nil
-
-		// Save what's left after reading erasureBlockSize.
-		totalLeft = totalLeft - erasureBlockSize
+	// Get data blocks from encoded blocks.
+	dataBlocks, err := getDataBlocks(enBlocks, e.DataBlocks, len(buffer))
+	if err != nil {
+		return 0, err
 	}
-	return bufWriter, nil
+
+	// Copy data blocks.
+	copy(buffer, dataBlocks[bufferOffset:])
+
+	// Relenquish memory.
+	dataBlocks = nil
+
+	return int64(len(buffer)), nil
 }

erasure-utils.go

@@ -16,13 +16,31 @@
 
 package main
 
+import "github.com/klauspost/reedsolomon"
+
 // getDataBlocks - fetches the data block only part of the input encoded blocks.
-func getDataBlocks(enBlocks [][]byte, dataBlocks int, curBlockSize int) (data []byte) {
-	for _, block := range enBlocks[:dataBlocks] {
+func getDataBlocks(enBlocks [][]byte, dataBlocks int, curBlockSize int) (data []byte, err error) {
+	if len(enBlocks) < dataBlocks {
+		return nil, reedsolomon.ErrTooFewShards
+	}
+	size := 0
+	blocks := enBlocks[:dataBlocks]
+	for _, block := range blocks {
+		size += len(block)
+	}
+	if size < curBlockSize {
+		return nil, reedsolomon.ErrShortData
+	}
+	write := curBlockSize
+	for _, block := range blocks {
+		if write < len(block) {
+			data = append(data, block[:write]...)
+			return data, nil
+		}
 		data = append(data, block...)
+		write -= len(block)
 	}
-	data = data[:curBlockSize]
-	return data
+	return data, nil
 }
 
 // checkBlockSize return the size of a single block.

format-config-v1.go

@@ -115,7 +115,7 @@ func reorderDisks(bootstrapDisks []StorageAPI, formatConfigs []*formatConfigV1)
 
 // loadFormat - load format from disk.
 func loadFormat(disk StorageAPI) (format *formatConfigV1, err error) {
-	buffer := make([]byte, blockSize)
+	buffer := make([]byte, blockSizeV1)
 	offset := int64(0)
 	var n int64
 	n, err = disk.ReadFile(minioMetaBucket, formatConfigFile, offset, buffer)

fs-v1-metadata.go

@@ -57,7 +57,7 @@ func (m *fsMetaV1) AddObjectPart(partNumber int, partName string, partETag strin
 
 // readFSMetadata - returns the object metadata `fs.json` content.
 func (fs fsObjects) readFSMetadata(bucket, object string) (fsMeta fsMetaV1, err error) {
-	buffer := make([]byte, blockSize)
+	buffer := make([]byte, blockSizeV1)
 	n, err := fs.storage.ReadFile(bucket, path.Join(object, fsMetaJSONFile), int64(0), buffer)
 	if err != nil {
 		return fsMetaV1{}, err

fs-v1-multipart.go

@@ -305,7 +305,7 @@ func (fs fsObjects) putObjectPartCommon(bucket string, object string, uploadID s
 	// Initialize md5 writer.
 	md5Writer := md5.New()
 
-	var buf = make([]byte, blockSize)
+	var buf = make([]byte, blockSizeV1)
 	for {
 		n, err := io.ReadFull(data, buf)
 		if err == io.EOF {
@@ -476,7 +476,7 @@ func (fs fsObjects) CompleteMultipartUpload(bucket string, object string, upload
 	}
 
 	tempObj := path.Join(tmpMetaPrefix, uploadID, "object1")
-	var buffer = make([]byte, blockSize)
+	var buffer = make([]byte, blockSizeV1)
 
 	// Loop through all parts, validate them and then commit to disk.
 	for i, part := range parts {

fs-v1.go

@@ -160,8 +160,8 @@ func (fs fsObjects) GetObject(bucket, object string, startOffset int64, length i
 	for totalLeft > 0 {
 		// Figure out the right blockSize as it was encoded before.
 		var curBlockSize int64
-		if blockSize < totalLeft {
-			curBlockSize = blockSize
+		if blockSizeV1 < totalLeft {
+			curBlockSize = blockSizeV1
 		} else {
 			curBlockSize = totalLeft
 		}
@@ -212,10 +212,6 @@ func (fs fsObjects) GetObjectInfo(bucket, object string) (ObjectInfo, error) {
 	}, nil
 }
 
-const (
-	blockSize = 4 * 1024 * 1024 // 4MiB.
-)
-
 // PutObject - create an object.
 func (fs fsObjects) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string) (string, error) {
 	// Verify if bucket is valid.
@@ -245,7 +241,7 @@ func (fs fsObjects) PutObject(bucket string, object string, size int64, data io.
 		}
 	} else {
 		// Allocate buffer.
-		buf := make([]byte, blockSize)
+		buf := make([]byte, blockSizeV1)
 		for {
 			n, rErr := data.Read(buf)
 			if rErr == io.EOF {

object-common.go

@@ -21,6 +21,11 @@ import (
 	"sync"
 )
 
+const (
+	// Block size used for all internal operations version 1.
+	blockSizeV1 = 10 * 1024 * 1024 // 10MiB.
+)
+
 // Common initialization needed for both object layers.
 func initObjectLayer(storageDisks ...StorageAPI) error {
 	// This happens for the first time, but keep this here since this

xl-v1-healing.go

@@ -42,7 +42,7 @@ func (xl xlObjects) readAllXLMetadata(bucket, object string) ([]xlMetaV1, []erro
 		go func(index int, disk StorageAPI) {
 			defer wg.Done()
 			offset := int64(0)
-			var buffer = make([]byte, blockSize)
+			var buffer = make([]byte, blockSizeV1)
 			n, err := disk.ReadFile(bucket, xlMetaPath, offset, buffer)
 			if err != nil {
 				errs[index] = err

xl-v1-metadata.go

@@ -25,9 +25,8 @@ import (
 	"time"
 )
 
-// Erasure block size.
 const (
-	erasureBlockSize          = 4 * 1024 * 1024 // 4MiB.
+	// Erasure related constants.
 	erasureAlgorithmKlauspost = "klauspost/reedsolomon/vandermonde"
 	erasureAlgorithmISAL      = "isa-l/reedsolomon/cauchy"
 )
@@ -140,8 +139,8 @@ func (xl xlObjects) readXLMetadata(bucket, object string) (xlMeta xlMetaV1, err
 	// Count for errors encountered.
 	var xlJSONErrCount = 0
 
-	// Allocate 4MiB buffer.
-	buffer := make([]byte, blockSize)
+	// Allocate 10MiB buffer.
+	buffer := make([]byte, blockSizeV1)
 
 	// Return the first successful lookup from a random list of disks.
 	for xlJSONErrCount < len(xl.storageDisks) {
@@ -168,7 +167,7 @@ func newXLMetaV1(dataBlocks, parityBlocks int) (xlMeta xlMetaV1) {
 	xlMeta.Erasure.Algorithm = erasureAlgorithmKlauspost
 	xlMeta.Erasure.DataBlocks = dataBlocks
 	xlMeta.Erasure.ParityBlocks = parityBlocks
-	xlMeta.Erasure.BlockSize = erasureBlockSize
+	xlMeta.Erasure.BlockSize = blockSizeV1
 	xlMeta.Erasure.Distribution = randErasureDistribution(dataBlocks + parityBlocks)
 	return xlMeta
 }

xl-v1-multipart-common.go

@@ -81,7 +81,7 @@ func readUploadsJSON(bucket, object string, storageDisks ...StorageAPI) (uploadI
 		// Read `uploads.json` in a routine.
 		go func(index int, disk StorageAPI) {
 			defer wg.Done()
-			var buffer = make([]byte, blockSize)
+			var buffer = make([]byte, blockSizeV1) // Allocate blockSized buffer.
 			n, rErr := disk.ReadFile(minioMetaBucket, uploadJSONPath, int64(0), buffer)
 			if rErr != nil {
 				errs[index] = rErr

xl-v1-multipart.go

@@ -146,7 +146,10 @@ func (xl xlObjects) putObjectPartCommon(bucket string, object string, uploadID s
 	// Initialize md5 writer.
 	md5Writer := md5.New()
 
-	buf := make([]byte, blockSize)
+	// Allocate blocksized buffer for reading.
+	buf := make([]byte, blockSizeV1)
+
+	// Read until io.EOF, fill the allocated buf.
 	for {
 		var n int
 		n, err = io.ReadFull(data, buf)
@@ -167,6 +170,8 @@ func (xl xlObjects) putObjectPartCommon(bucket string, object string, uploadID s
 			return "", toObjectErr(errUnexpected, bucket, object)
 		}
 	}
+
+	// Calculate new md5sum.
 	newMD5Hex := hex.EncodeToString(md5Writer.Sum(nil))
 	if md5Hex != "" {
 		if newMD5Hex != md5Hex {
@@ -174,6 +179,7 @@ func (xl xlObjects) putObjectPartCommon(bucket string, object string, uploadID s
 		}
 	}
 
+	// Rename temporary part file to its final location.
 	partPath := path.Join(mpartMetaPrefix, bucket, object, uploadID, partSuffix)
 	err = xl.renameObject(minioMetaBucket, tmpPartPath, minioMetaBucket, partPath)
 	if err != nil {

xl-v1-object.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"bytes"
 	"crypto/md5"
 	"encoding/hex"
 	"io"
@@ -51,27 +50,42 @@ func (xl xlObjects) GetObject(bucket, object string, startOffset int64, length i
 	if err != nil {
 		return toObjectErr(err, bucket, object)
 	}
-	totalLeft := length
 	for ; partIndex < len(xlMeta.Parts); partIndex++ {
 		part := xlMeta.Parts[partIndex]
-		var buffer io.Reader
-		buffer, err = erasure.ReadFile(bucket, pathJoin(object, part.Name), partOffset, part.Size)
-		if err != nil {
-			return err
-		}
-		if int64(buffer.(*bytes.Buffer).Len()) > totalLeft {
-			if _, err := io.CopyN(writer, buffer, totalLeft); err != nil {
+		totalLeft := part.Size
+		beginOffset := int64(0)
+		for totalLeft > 0 {
+			var curBlockSize int64
+			if xlMeta.Erasure.BlockSize < totalLeft {
+				curBlockSize = xlMeta.Erasure.BlockSize
+			} else {
+				curBlockSize = totalLeft
+			}
+			var buffer = make([]byte, curBlockSize)
+			var n int64
+			n, err = erasure.ReadFile(bucket, pathJoin(object, part.Name), partOffset, beginOffset, buffer)
+			if err != nil {
 				return err
 			}
-			return nil
-		}
-		n, err := io.Copy(writer, buffer)
-		if err != nil {
-			return err
+			if length > int64(len(buffer)) {
+				var m int
+				m, err = writer.Write(buffer)
+				if err != nil {
+					return err
+				}
+				length -= int64(m)
+			} else {
+				_, err = writer.Write(buffer[:length])
+				if err != nil {
+					return err
+				}
+				return nil
+			}
+			totalLeft -= partOffset + n
+			beginOffset += n
+			// Reset part offset to 0 to read rest of the parts from the beginning.
+			partOffset = 0
 		}
-		totalLeft -= n
-		// Reset part offset to 0 to read rest of the parts from the beginning.
-		partOffset = 0
 	}
 	return nil
 }
@@ -222,7 +236,8 @@ func (xl xlObjects) PutObject(bucket string, object string, size int64, data io.
 	// Initialize md5 writer.
 	md5Writer := md5.New()
 
-	buf := make([]byte, blockSize)
+	// Allocated blockSized buffer for reading.
+	buf := make([]byte, blockSizeV1)
 	for {
 		var n int
 		n, err = io.ReadFull(data, buf)