xl/fs: Make i/o operations atomic. (#1496)

fs-objects-multipart.go

@@ -72,6 +72,9 @@ func (fs fsObjects) CompleteMultipartUpload(bucket string, object string, upload
 		var fileReader io.ReadCloser
 		fileReader, err = fs.storage.ReadFile(minioMetaBucket, multipartPartFile, 0)
 		if err != nil {
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", clErr
+			}
 			if err == errFileNotFound {
 				return "", InvalidPart{}
 			}
@@ -79,10 +82,16 @@ func (fs fsObjects) CompleteMultipartUpload(bucket string, object string, upload
 		}
 		_, err = io.Copy(fileWriter, fileReader)
 		if err != nil {
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", clErr
+			}
 			return "", err
 		}
 		err = fileReader.Close()
 		if err != nil {
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", clErr
+			}
 			return "", err
 		}
 		md5Sums = append(md5Sums, part.ETag)
@@ -90,25 +99,33 @@ func (fs fsObjects) CompleteMultipartUpload(bucket string, object string, upload
 
 	err = fileWriter.Close()
 	if err != nil {
+		if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+			return "", clErr
+		}
 		return "", err
 	}
 
+	// Rename the file back to original location, if not delete the
+	// temporary object.
+	err = fs.storage.RenameFile(minioMetaBucket, tempObj, bucket, object)
+	if err != nil {
+		if derr := fs.storage.DeleteFile(minioMetaBucket, tempObj); derr != nil {
+			return "", toObjectErr(derr, minioMetaBucket, tempObj)
+		}
+		return "", toObjectErr(err, bucket, object)
+	}
+
 	// Save the s3 md5.
 	s3MD5, err := makeS3MD5(md5Sums...)
 	if err != nil {
 		return "", err
 	}
 
-	// Cleanup all the parts.
+	// Cleanup all the parts if everything else has been safely committed.
 	if err = cleanupUploadedParts(fs.storage, mpartMetaPrefix, bucket, object, uploadID); err != nil {
 		return "", err
 	}
 
-	err = fs.storage.RenameFile(minioMetaBucket, tempObj, bucket, object)
-	if err != nil {
-		return "", toObjectErr(err, bucket, object)
-	}
-
 	// Return md5sum.
 	return s3MD5, nil
 }

object-common-multipart.go

@@ -72,10 +72,16 @@ func newMultipartUploadCommon(storage StorageAPI, bucket string, object string)
 			}
 			// Close the writer.
 			if err = w.Close(); err != nil {
+				if clErr := safeCloseAndRemove(w); clErr != nil {
+					return "", toObjectErr(clErr, minioMetaBucket, tempUploadIDPath)
+				}
 				return "", toObjectErr(err, minioMetaBucket, tempUploadIDPath)
 			}
 			err = storage.RenameFile(minioMetaBucket, tempUploadIDPath, minioMetaBucket, uploadIDPath)
 			if err != nil {
+				if derr := storage.DeleteFile(minioMetaBucket, tempUploadIDPath); derr != nil {
+					return "", toObjectErr(derr, minioMetaBucket, tempUploadIDPath)
+				}
 				return "", toObjectErr(err, minioMetaBucket, uploadIDPath)
 			}
 			return uploadID, nil
@@ -124,19 +130,25 @@ func putObjectPartCommon(storage StorageAPI, bucket string, object string, uploa
 	// Instantiate checksum hashers and create a multiwriter.
 	if size > 0 {
 		if _, err = io.CopyN(multiWriter, data, size); err != nil {
-			safeCloseAndRemove(fileWriter)
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", toObjectErr(clErr, bucket, object)
+			}
 			return "", toObjectErr(err, bucket, object)
 		}
 		// Reader shouldn't have more data what mentioned in size argument.
 		// reading one more byte from the reader to validate it.
 		// expected to fail, success validates existence of more data in the reader.
 		if _, err = io.CopyN(ioutil.Discard, data, 1); err == nil {
-			safeCloseAndRemove(fileWriter)
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", toObjectErr(clErr, bucket, object)
+			}
 			return "", UnExpectedDataSize{Size: int(size)}
 		}
 	} else {
 		if _, err = io.Copy(multiWriter, data); err != nil {
-			safeCloseAndRemove(fileWriter)
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", toObjectErr(clErr, bucket, object)
+			}
 			return "", toObjectErr(err, bucket, object)
 		}
 	}
@@ -144,12 +156,17 @@ func putObjectPartCommon(storage StorageAPI, bucket string, object string, uploa
 	newMD5Hex := hex.EncodeToString(md5Writer.Sum(nil))
 	if md5Hex != "" {
 		if newMD5Hex != md5Hex {
-			safeCloseAndRemove(fileWriter)
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", toObjectErr(clErr, bucket, object)
+			}
 			return "", BadDigest{md5Hex, newMD5Hex}
 		}
 	}
 	err = fileWriter.Close()
 	if err != nil {
+		if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+			return "", toObjectErr(clErr, bucket, object)
+		}
 		return "", err
 	}
 
@@ -157,7 +174,10 @@ func putObjectPartCommon(storage StorageAPI, bucket string, object string, uploa
 	partSuffixMD5Path := path.Join(mpartMetaPrefix, bucket, object, partSuffixMD5)
 	err = storage.RenameFile(minioMetaBucket, partSuffixPath, minioMetaBucket, partSuffixMD5Path)
 	if err != nil {
-		return "", err
+		if derr := storage.DeleteFile(minioMetaBucket, partSuffixPath); derr != nil {
+			return "", toObjectErr(derr, minioMetaBucket, partSuffixPath)
+		}
+		return "", toObjectErr(err, minioMetaBucket, partSuffixMD5Path)
 	}
 	return newMD5Hex, nil
 }

object-common.go

@@ -174,6 +174,9 @@ func putObjectCommon(storage StorageAPI, bucket string, object string, size int6
 	}
 	err = fileWriter.Close()
 	if err != nil {
+		if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+			return "", clErr
+		}
 		return "", err
 	}
 	err = storage.RenameFile(minioMetaBucket, tempObj, bucket, object)

pkg/safe/safe.go

@@ -70,9 +70,8 @@ func (f *File) Close() error {
 // error if any.
 func (f *File) CloseAndRemove() error {
 	// close the embedded fd
-	if err := f.File.Close(); err != nil {
+	f.File.Close()
-		return err
+
-	}
 	// Remove the temp file.
 	if err := os.Remove(f.Name()); err != nil {
 		return err

xl-erasure-v1-metadata.go

@@ -29,7 +29,6 @@ type xlMetaV1 struct {
 		Size    int64     `json:"size"`
 		ModTime time.Time `json:"modTime"`
 		Version int64     `json:"version"`
-		Deleted bool      `json:"deleted"`
 	} `json:"stat"`
 	Erasure struct {
 		DataBlocks   int   `json:"data"`

xl-erasure-v1.go

@@ -18,7 +18,6 @@ package main
 
 import (
 	"fmt"
-	"io"
 	"os"
 	slashpath "path"
 	"strings"
@@ -464,74 +463,23 @@ func (xl XL) DeleteFile(volume, path string) error {
 		return errInvalidArgument
 	}
 
-	// Lock right before reading from disk.
-	nsMutex.RLock(volume, path)
-	partsMetadata, errs := xl.getPartsMetadata(volume, path)
-	nsMutex.RUnlock(volume, path)
-
-	var err error
-
-	// List all the file versions on existing files.
-	versions := listFileVersions(partsMetadata, errs)
-	// Get highest file version.
-	higherVersion := highestInt(versions)
-
-	// find online disks and meta data of higherVersion
-	var mdata *xlMetaV1
-	onlineDiskCount := 0
-	errFileNotFoundErr := 0
-	for index, metadata := range partsMetadata {
-		if errs[index] == nil {
-			onlineDiskCount++
-			if metadata.Stat.Version == higherVersion && mdata == nil {
-				mdata = &metadata
-			}
-		} else if errs[index] == errFileNotFound {
-			errFileNotFoundErr++
-		}
-	}
-
-	if errFileNotFoundErr == len(xl.storageDisks) {
-		return errFileNotFound
-	} else if mdata == nil || onlineDiskCount < xl.writeQuorum {
-		// return error if mdata is empty or onlineDiskCount doesn't meet write quorum
-		return errWriteQuorum
-	}
-
-	// Increment to have next higher version.
-	higherVersion++
-
-	xlMetaV1FilePath := slashpath.Join(path, xlMetaV1File)
-	deleteMetaData := (onlineDiskCount == len(xl.storageDisks))
-
-	// Set higher version to indicate file operation
-	mdata.Stat.Version = higherVersion
-	mdata.Stat.Deleted = true
-
 	nsMutex.Lock(volume, path)
 	defer nsMutex.Unlock(volume, path)
 
 	errCount := 0
 	// Update meta data file and remove part file
 	for index, disk := range xl.storageDisks {
-		// no need to operate on failed disks
+		erasureFilePart := slashpath.Join(path, fmt.Sprintf("file.%d", index))
-		if errs[index] != nil {
+		err := disk.DeleteFile(volume, erasureFilePart)
-			errCount++
-			continue
-		}
-
-		// update meta data about delete operation
-		var metadataWriter io.WriteCloser
-		metadataWriter, err = disk.CreateFile(volume, xlMetaV1FilePath)
 		if err != nil {
 			log.WithFields(logrus.Fields{
 				"volume": volume,
 				"path":   path,
-			}).Errorf("CreateFile failed with %s", err)
+			}).Errorf("DeleteFile failed with %s", err)
 
 			errCount++
 
-			// We can safely allow CreateFile errors up to len(xl.storageDisks) - xl.writeQuorum
+			// We can safely allow DeleteFile errors up to len(xl.storageDisks) - xl.writeQuorum
 			// otherwise return failure.
 			if errCount <= len(xl.storageDisks)-xl.writeQuorum {
 				continue
@@ -540,42 +488,8 @@ func (xl XL) DeleteFile(volume, path string) error {
 			return err
 		}
 
-		err = mdata.Write(metadataWriter)
+		xlMetaV1FilePath := slashpath.Join(path, "file.json")
-		if err != nil {
+		err = disk.DeleteFile(volume, xlMetaV1FilePath)
-			log.WithFields(logrus.Fields{
-				"volume":    volume,
-				"path":      path,
-				"diskIndex": index,
-			}).Errorf("Writing metadata failed with %s", err)
-
-			errCount++
-
-			// We can safely allow CreateFile errors up to len(xl.storageDisks) - xl.writeQuorum
-			// otherwise return failure.
-			if errCount <= len(xl.storageDisks)-xl.writeQuorum {
-				continue
-			}
-			// Safely close and remove.
-			if err = safeCloseAndRemove(metadataWriter); err != nil {
-				return err
-			}
-			return err
-		}
-		// Safely wrote, now rename to its actual location.
-		if err = metadataWriter.Close(); err != nil {
-			log.WithFields(logrus.Fields{
-				"volume":    volume,
-				"path":      path,
-				"diskIndex": index,
-			}).Errorf("Metadata commit failed with %s", err)
-			if err = safeCloseAndRemove(metadataWriter); err != nil {
-				return err
-			}
-			return err
-		}
-
-		erasureFilePart := slashpath.Join(path, fmt.Sprintf("file.%d", index))
-		err = disk.DeleteFile(volume, erasureFilePart)
 		if err != nil {
 			log.WithFields(logrus.Fields{
 				"volume": volume,
@@ -584,7 +498,7 @@ func (xl XL) DeleteFile(volume, path string) error {
 
 			errCount++
 
-			// We can safely allow CreateFile errors up to len(xl.storageDisks) - xl.writeQuorum
+			// We can safely allow DeleteFile errors up to len(xl.storageDisks) - xl.writeQuorum
 			// otherwise return failure.
 			if errCount <= len(xl.storageDisks)-xl.writeQuorum {
 				continue
@@ -594,24 +508,6 @@ func (xl XL) DeleteFile(volume, path string) error {
 		}
 	}
 
-	// Remove meta data file only if deleteMetaData is true.
-	if deleteMetaData {
-		for index, disk := range xl.storageDisks {
-			// no need to operate on failed disks
-			if errs[index] != nil {
-				continue
-			}
-
-			err = disk.DeleteFile(volume, xlMetaV1FilePath)
-			if err != nil {
-				// No need to return the error as we updated the meta data file previously
-				log.WithFields(logrus.Fields{
-					"volume": volume,
-					"path":   path,
-				}).Errorf("DeleteFile failed with %s", err)
-			}
-		}
-	}
 	// Return success.
 	return nil
 }

xl-objects-multipart.go

@@ -119,7 +119,6 @@ func (xl xlObjects) CompleteMultipartUpload(bucket string, object string, upload
 
 		multipartObjSuffix := path.Join(object, partNumToPartFileName(part.PartNumber))
 		err = xl.storage.RenameFile(minioMetaBucket, multipartPartFile, bucket, multipartObjSuffix)
-		// TODO: We need a way to roll back if of the renames failed.
 		if err != nil {
 			return "", err
 		}
@@ -153,14 +152,35 @@ func (xl xlObjects) CompleteMultipartUpload(bucket string, object string, upload
 	}
 	// Close the writer.
 	if err = w.Close(); err != nil {
+		if err = safeCloseAndRemove(w); err != nil {
+			return "", err
+		}
 		return "", err
 	}
 	multipartObjFile := path.Join(object, multipartMetaFile)
 	err = xl.storage.RenameFile(minioMetaBucket, tempMultipartMetaFile, bucket, multipartObjFile)
 	if err != nil {
+		if derr := xl.storage.DeleteFile(minioMetaBucket, tempMultipartMetaFile); derr != nil {
+			return "", toObjectErr(err, minioMetaBucket, tempMultipartMetaFile)
+		}
 		return "", toObjectErr(err, bucket, multipartObjFile)
 	}
 
+	// Attempt a rename of the upload id to temporary location, if
+	// successful then delete it.
+	uploadIDPath := path.Join(mpartMetaPrefix, bucket, object, uploadID)
+	tempUploadIDPath := path.Join(tmpMetaPrefix, bucket, object, uploadID)
+	if err = xl.storage.RenameFile(minioMetaBucket, uploadIDPath, minioMetaBucket, tempUploadIDPath); err == nil {
+		if err = xl.storage.DeleteFile(minioMetaBucket, tempUploadIDPath); err != nil {
+			return "", toObjectErr(err, minioMetaBucket, tempUploadIDPath)
+		}
+		return s3MD5, nil
+	}
+	// Rename if failed attempt to delete the original file.
+	err = xl.storage.DeleteFile(minioMetaBucket, uploadIDPath)
+	if err != nil {
+		return "", toObjectErr(err, minioMetaBucket, uploadIDPath)
+	}
 	// Return md5sum.
 	return s3MD5, nil
 }