list/xl: Fix the way marker is handled in leafDirectory verification.

xl-v1-healfile.go

@@ -0,0 +1,256 @@
+/*
+ * Minio Cloud Storage, (C) 2016 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 main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	slashpath "path"
+	"strconv"
+)
+
+func (xl XL) selfHeal(volume string, path string) error {
+	totalShards := xl.DataBlocks + xl.ParityBlocks
+	needsSelfHeal := make([]bool, totalShards)
+	var metadata = make(map[string]string)
+	var readers = make([]io.Reader, totalShards)
+	var writers = make([]io.WriteCloser, totalShards)
+	for index, disk := range xl.storageDisks {
+		metadataFile := slashpath.Join(path, metadataFile)
+
+		// Start from the beginning, we are not reading partial metadata files.
+		offset := int64(0)
+
+		metadataReader, err := disk.ReadFile(volume, metadataFile, offset)
+		if err != nil {
+			if err != errFileNotFound {
+				continue
+			}
+			// Needs healing if part.json is not found
+			needsSelfHeal[index] = true
+			continue
+		}
+		defer metadataReader.Close()
+
+		decoder := json.NewDecoder(metadataReader)
+		if err = decoder.Decode(&metadata); err != nil {
+			// needs healing if parts.json is not parsable
+			needsSelfHeal[index] = true
+		}
+
+		erasurePart := slashpath.Join(path, fmt.Sprintf("part.%d", index))
+		erasuredPartReader, err := disk.ReadFile(volume, erasurePart, offset)
+		if err != nil {
+			if err == errFileNotFound {
+				// Needs healing if part file not found
+				needsSelfHeal[index] = true
+			}
+			return err
+		}
+		readers[index] = erasuredPartReader
+		defer erasuredPartReader.Close()
+	}
+
+	// Check if there is atleast one part that needs to be healed.
+	atleastOneSelfHeal := false
+	for _, shNeeded := range needsSelfHeal {
+		if shNeeded {
+			atleastOneSelfHeal = true
+			break
+		}
+	}
+	if !atleastOneSelfHeal {
+		// Return if healing not needed anywhere.
+		return nil
+	}
+
+	// create writers for parts where healing is needed.
+	for index, shNeeded := range needsSelfHeal {
+		if !shNeeded {
+			continue
+		}
+		var err error
+		erasurePart := slashpath.Join(path, fmt.Sprintf("part.%d", index))
+		writers[index], err = xl.storageDisks[index].CreateFile(volume, erasurePart)
+		if err != nil {
+			// Unexpected error
+			closeAndRemoveWriters(writers...)
+			return err
+		}
+	}
+	size, err := strconv.ParseInt(metadata["file.size"], 10, 64)
+	if err != nil {
+		closeAndRemoveWriters(writers...)
+		return err
+	}
+	var totalLeft = size
+	for totalLeft > 0 {
+		// Figure out the right blockSize.
+		var curBlockSize int
+		if erasureBlockSize < totalLeft {
+			curBlockSize = erasureBlockSize
+		} else {
+			curBlockSize = int(totalLeft)
+		}
+		// Calculate the current shard size.
+		curShardSize := getEncodedBlockLen(curBlockSize, xl.DataBlocks)
+		enShards := make([][]byte, totalShards)
+		// Loop through all readers and read.
+		for index, reader := range readers {
+			// Initialize shard slice and fill the data from each parts.
+			// ReedSolomon.Verify() expects that slice is not nil even if the particular
+			// part needs healing.
+			enShards[index] = make([]byte, curShardSize)
+			if needsSelfHeal[index] {
+				// Skip reading if the part needs healing.
+				continue
+			}
+			_, e := io.ReadFull(reader, enShards[index])
+			if e != nil && e != io.ErrUnexpectedEOF {
+				enShards[index] = nil
+			}
+		}
+
+		// Check blocks if they are all zero in length.
+		if checkBlockSize(enShards) == 0 {
+			err = errors.New("Data likely corrupted, all blocks are zero in length.")
+			return err
+		}
+
+		// Verify the shards.
+		ok, e := xl.ReedSolomon.Verify(enShards)
+		if e != nil {
+			closeAndRemoveWriters(writers...)
+			return e
+		}
+
+		// Verification failed, shards require reconstruction.
+		if !ok {
+			for index, shNeeded := range needsSelfHeal {
+				if shNeeded {
+					// Reconstructs() reconstructs the parts if the array is nil.
+					enShards[index] = nil
+				}
+			}
+			e = xl.ReedSolomon.Reconstruct(enShards)
+			if e != nil {
+				closeAndRemoveWriters(writers...)
+				return e
+			}
+			// Verify reconstructed shards again.
+			ok, e = xl.ReedSolomon.Verify(enShards)
+			if e != nil {
+				closeAndRemoveWriters(writers...)
+				return e
+			}
+			if !ok {
+				// Shards cannot be reconstructed, corrupted data.
+				e = errors.New("Verification failed after reconstruction, data likely corrupted.")
+				closeAndRemoveWriters(writers...)
+				return e
+			}
+		}
+		for index, shNeeded := range needsSelfHeal {
+			if !shNeeded {
+				continue
+			}
+			_, e := writers[index].Write(enShards[index])
+			if e != nil {
+				closeAndRemoveWriters(writers...)
+				return e
+			}
+		}
+		totalLeft = totalLeft - erasureBlockSize
+	}
+
+	// After successful healing Close() the writer so that the temp
+	// files are committed to their location.
+	for index, shNeeded := range needsSelfHeal {
+		if !shNeeded {
+			continue
+		}
+		writers[index].Close()
+	}
+
+	// Write part.json where ever healing was done.
+	var metadataWriters = make([]io.WriteCloser, len(xl.storageDisks))
+	for index, shNeeded := range needsSelfHeal {
+		if !shNeeded {
+			continue
+		}
+		metadataFile := slashpath.Join(path, metadataFile)
+		metadataWriters[index], err = xl.storageDisks[index].CreateFile(volume, metadataFile)
+		if err != nil {
+			closeAndRemoveWriters(writers...)
+			return err
+		}
+	}
+	metadataBytes, err := json.Marshal(metadata)
+	if err != nil {
+		closeAndRemoveWriters(metadataWriters...)
+		return err
+	}
+	for index, shNeeded := range needsSelfHeal {
+		if !shNeeded {
+			continue
+		}
+		_, err = metadataWriters[index].Write(metadataBytes)
+		if err != nil {
+			closeAndRemoveWriters(metadataWriters...)
+			return err
+		}
+	}
+
+	// Metadata written for all the healed parts hence Close() so that
+	// temp files can be committed.
+	for index := range xl.storageDisks {
+		if !needsSelfHeal[index] {
+			continue
+		}
+		metadataWriters[index].Close()
+	}
+	return nil
+}
+
+// self heal.
+type selfHeal struct {
+	volume string
+	path   string
+	errCh  chan<- error
+}
+
+// selfHealRoutine - starts a go routine and listens on a channel for healing requests.
+func (xl *XL) selfHealRoutine() {
+	xl.selfHealCh = make(chan selfHeal)
+
+	// Healing request can be made like this:
+	// errCh := make(chan error)
+	// xl.selfHealCh <- selfHeal{"testbucket", "testobject", errCh}
+	// fmt.Println(<-errCh)
+	go func() {
+		for sh := range xl.selfHealCh {
+			if sh.volume == "" || sh.path == "" {
+				sh.errCh <- errors.New("volume or path can not be empty")
+				continue
+			}
+			xl.selfHeal(sh.volume, sh.path)
+			sh.errCh <- nil
+		}
+	}()
+}