Move nslocking from s3 layer to object layer (#5382)

Fixes #5350

cmd/admin-handlers.go

@@ -412,11 +412,7 @@ func (adminAPI adminAPIHandlers) ClearLocksHandler(w http.ResponseWriter, r *htt
 		errorIf(err, "Failed to marshal lock information into json.")
 		return
 	}
-
+	newObjectLayerFn().ClearLocks(volLocks)
-	// Remove lock matching bucket/prefix held longer than duration.
-	for _, volLock := range volLocks {
-		globalNSMutex.ForceUnlock(volLock.Bucket, volLock.Object)
-	}
 
 	// Reply with list of locks cleared, as json.
 	writeSuccessResponseJSON(w, jsonBytes)

cmd/benchmark-utils_test.go

@@ -239,7 +239,7 @@ func runGetObjectBenchmark(b *testing.B, obj ObjectLayer, objSize int) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		var buffer = new(bytes.Buffer)
-		err = obj.GetObject(bucket, "object"+strconv.Itoa(i%10), 0, int64(objSize), buffer)
+		err = obj.GetObject(bucket, "object"+strconv.Itoa(i%10), 0, int64(objSize), buffer, "")
 		if err != nil {
 			b.Error(err)
 		}
@@ -402,7 +402,7 @@ func runGetObjectBenchmarkParallel(b *testing.B, obj ObjectLayer, objSize int) {
 	b.RunParallel(func(pb *testing.PB) {
 		i := 0
 		for pb.Next() {
-			err = obj.GetObject(bucket, "object"+strconv.Itoa(i), 0, int64(objSize), ioutil.Discard)
+			err = obj.GetObject(bucket, "object"+strconv.Itoa(i), 0, int64(objSize), ioutil.Discard, "")
 			if err != nil {
 				b.Error(err)
 			}

cmd/bucket-handlers.go

@@ -301,16 +301,9 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 				}
 				return
 			}
-			objectLock := globalNSMutex.NewNSLock(bucket, obj.ObjectName)
+			dErr := objectAPI.DeleteObject(bucket, obj.ObjectName)
-			if timedOutErr := objectLock.GetLock(globalObjectTimeout); timedOutErr != nil {
+			if dErr != nil {
-				dErrs[i] = timedOutErr
+				dErrs[i] = dErr
-			} else {
-				defer objectLock.Unlock()
-
-				dErr := objectAPI.DeleteObject(bucket, obj.ObjectName)
-				if dErr != nil {
-					dErrs[i] = dErr
-				}
 			}
 		}(index, object)
 	}
@@ -404,13 +397,6 @@ func (api objectAPIHandlers) PutBucketHandler(w http.ResponseWriter, r *http.Req
 		return
 	}
 
-	bucketLock := globalNSMutex.NewNSLock(bucket, "")
-	if bucketLock.GetLock(globalObjectTimeout) != nil {
-		writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-		return
-	}
-	defer bucketLock.Unlock()
-
 	// Proceed to creating a bucket.
 	err := objectAPI.MakeBucketWithLocation(bucket, "")
 	if err != nil {
@@ -559,13 +545,6 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 		return
 	}
 
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
-	if objectLock.GetLock(globalObjectTimeout) != nil {
-		writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-		return
-	}
-	defer objectLock.Unlock()
-
 	hashReader, err := hash.NewReader(fileBody, fileSize, "", "")
 	if err != nil {
 		errorIf(err, "Unable to initialize hashReader.")

cmd/bucket-policy.go

@@ -148,15 +148,8 @@ func initBucketPolicies(objAPI ObjectLayer) error {
 func readBucketPolicyJSON(bucket string, objAPI ObjectLayer) (bucketPolicyReader io.Reader, err error) {
 	policyPath := pathJoin(bucketConfigPrefix, bucket, bucketPolicyConfig)
 
-	// Acquire a read lock on policy config before reading.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, policyPath)
-	if err = objLock.GetRLock(globalOperationTimeout); err != nil {
-		return nil, err
-	}
-	defer objLock.RUnlock()
-
 	var buffer bytes.Buffer
-	err = objAPI.GetObject(minioMetaBucket, policyPath, 0, -1, &buffer)
+	err = objAPI.GetObject(minioMetaBucket, policyPath, 0, -1, &buffer, "")
 	if err != nil {
 		if isErrObjectNotFound(err) || isErrIncompleteBody(err) {
 			return nil, BucketPolicyNotFound{Bucket: bucket}
@@ -190,12 +183,6 @@ func readBucketPolicy(bucket string, objAPI ObjectLayer) (policy.BucketAccessPol
 // if no policies are found.
 func removeBucketPolicy(bucket string, objAPI ObjectLayer) error {
 	policyPath := pathJoin(bucketConfigPrefix, bucket, bucketPolicyConfig)
-	// Acquire a write lock on policy config before modifying.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, policyPath)
-	if err := objLock.GetLock(globalOperationTimeout); err != nil {
-		return err
-	}
-	defer objLock.Unlock()
 	err := objAPI.DeleteObject(minioMetaBucket, policyPath)
 	if err != nil {
 		err = errors.Cause(err)
@@ -215,13 +202,6 @@ func writeBucketPolicy(bucket string, objAPI ObjectLayer, bpy policy.BucketAcces
 		return err
 	}
 	policyPath := pathJoin(bucketConfigPrefix, bucket, bucketPolicyConfig)
-	// Acquire a write lock on policy config before modifying.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, policyPath)
-	if err = objLock.GetLock(globalOperationTimeout); err != nil {
-		return err
-	}
-	defer objLock.Unlock()
-
 	hashReader, err := hash.NewReader(bytes.NewReader(buf), int64(len(buf)), "", getSHA256Hash(buf))
 	if err != nil {
 		errorIf(err, "Unable to set policy for the bucket %s", bucket)

cmd/event-notifier.go

@@ -365,15 +365,8 @@ func loadNotificationConfig(bucket string, objAPI ObjectLayer) (*notificationCon
 	// Construct the notification config path.
 	ncPath := path.Join(bucketConfigPrefix, bucket, bucketNotificationConfig)
 
-	// Acquire a write lock on notification config before modifying.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, ncPath)
-	if err := objLock.GetRLock(globalOperationTimeout); err != nil {
-		return nil, err
-	}
-	defer objLock.RUnlock()
-
 	var buffer bytes.Buffer
-	err := objAPI.GetObject(minioMetaBucket, ncPath, 0, -1, &buffer) // Read everything.
+	err := objAPI.GetObject(minioMetaBucket, ncPath, 0, -1, &buffer, "") // Read everything.
 	if err != nil {
 		// 'notification.xml' not found return
 		// 'errNoSuchNotifications'.  This is default when no
@@ -416,15 +409,8 @@ func loadListenerConfig(bucket string, objAPI ObjectLayer) ([]listenerConfig, er
 	// Construct the notification config path.
 	lcPath := path.Join(bucketConfigPrefix, bucket, bucketListenerConfig)
 
-	// Acquire a write lock on notification config before modifying.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, lcPath)
-	if err := objLock.GetRLock(globalOperationTimeout); err != nil {
-		return nil, err
-	}
-	defer objLock.RUnlock()
-
 	var buffer bytes.Buffer
-	err := objAPI.GetObject(minioMetaBucket, lcPath, 0, -1, &buffer)
+	err := objAPI.GetObject(minioMetaBucket, lcPath, 0, -1, &buffer, "")
 	if err != nil {
 		// 'listener.json' not found return
 		// 'errNoSuchNotifications'.  This is default when no
@@ -463,12 +449,6 @@ func persistNotificationConfig(bucket string, ncfg *notificationConfig, obj Obje
 
 	// build path
 	ncPath := path.Join(bucketConfigPrefix, bucket, bucketNotificationConfig)
-	// Acquire a write lock on notification config before modifying.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, ncPath)
-	if err = objLock.GetLock(globalOperationTimeout); err != nil {
-		return err
-	}
-	defer objLock.Unlock()
 
 	// write object to path
 	hashReader, err := hash.NewReader(bytes.NewReader(buf), int64(len(buf)), "", getSHA256Hash(buf))
@@ -494,12 +474,6 @@ func persistListenerConfig(bucket string, lcfg []listenerConfig, obj ObjectLayer
 
 	// build path
 	lcPath := path.Join(bucketConfigPrefix, bucket, bucketListenerConfig)
-	// Acquire a write lock on notification config before modifying.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, lcPath)
-	if err = objLock.GetLock(globalOperationTimeout); err != nil {
-		return err
-	}
-	defer objLock.Unlock()
 
 	// write object to path
 	hashReader, err := hash.NewReader(bytes.NewReader(buf), int64(len(buf)), "", getSHA256Hash(buf))
@@ -526,12 +500,6 @@ func removeNotificationConfig(bucket string, objAPI ObjectLayer) error {
 
 	ncPath := path.Join(bucketConfigPrefix, bucket, bucketNotificationConfig)
 
-	// Acquire a write lock on notification config before modifying.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, ncPath)
-	if err := objLock.GetLock(globalOperationTimeout); err != nil {
-		return err
-	}
-	defer objLock.Unlock()
 	return objAPI.DeleteObject(minioMetaBucket, ncPath)
 }
 
@@ -540,12 +508,6 @@ func removeListenerConfig(bucket string, objAPI ObjectLayer) error {
 	// make the path
 	lcPath := path.Join(bucketConfigPrefix, bucket, bucketListenerConfig)
 
-	// Acquire a write lock on notification config before modifying.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, lcPath)
-	if err := objLock.GetLock(globalOperationTimeout); err != nil {
-		return err
-	}
-	defer objLock.Unlock()
 	return objAPI.DeleteObject(minioMetaBucket, lcPath)
 }
 

cmd/fs-v1-multipart.go

@@ -109,7 +109,7 @@ func (fs fsObjects) listMultipartUploadIDs(bucketName, objectName, uploadIDMarke
 
 	// Hold the lock so that two parallel complete-multipart-uploads
 	// do not leave a stale uploads.json behind.
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucketName, objectName))
+	objectMPartPathLock := fs.nsMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucketName, objectName))
 	if err := objectMPartPathLock.GetRLock(globalListingTimeout); err != nil {
 		return nil, false, errors.Trace(err)
 	}
@@ -408,7 +408,7 @@ func (fs fsObjects) NewMultipartUpload(bucket, object string, meta map[string]st
 
 	// Hold the lock so that two parallel complete-multipart-uploads
 	// do not leave a stale uploads.json behind.
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
+	objectMPartPathLock := fs.nsMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
 	if err := objectMPartPathLock.GetLock(globalOperationTimeout); err != nil {
 		return "", err
 	}
@@ -437,17 +437,34 @@ func partToAppend(fsMeta fsMetaV1, fsAppendMeta fsMetaV1) (part objectPartInfo,
 // object. Internally incoming data is written to '.minio.sys/tmp' location
 // and safely renamed to '.minio.sys/multipart' for reach parts.
 func (fs fsObjects) CopyObjectPart(srcBucket, srcObject, dstBucket, dstObject, uploadID string, partID int,
-	startOffset int64, length int64, metadata map[string]string) (pi PartInfo, e error) {
+	startOffset int64, length int64, metadata map[string]string, srcEtag string) (pi PartInfo, e error) {
+
+	// Hold read locks on source object only if we are
+	// going to read data from source object.
+	objectSRLock := fs.nsMutex.NewNSLock(srcBucket, srcObject)
+	if err := objectSRLock.GetRLock(globalObjectTimeout); err != nil {
+		return pi, err
+	}
+	defer objectSRLock.RUnlock()
 
 	if err := checkNewMultipartArgs(srcBucket, srcObject, fs); err != nil {
 		return pi, err
 	}
 
+	if srcEtag != "" {
+		etag, err := fs.getObjectETag(srcBucket, srcObject)
+		if err != nil {
+			return pi, toObjectErr(err, srcBucket, srcObject)
+		}
+		if etag != srcEtag {
+			return pi, toObjectErr(errors.Trace(InvalidETag{}), srcBucket, srcObject)
+		}
+	}
 	// Initialize pipe.
 	pipeReader, pipeWriter := io.Pipe()
 
 	go func() {
-		if gerr := fs.GetObject(srcBucket, srcObject, startOffset, length, pipeWriter); gerr != nil {
+		if gerr := fs.getObject(srcBucket, srcObject, startOffset, length, pipeWriter, srcEtag); gerr != nil {
 			errorIf(gerr, "Unable to read %s/%s.", srcBucket, srcObject)
 			pipeWriter.CloseWithError(gerr)
 			return
@@ -491,7 +508,7 @@ func (fs fsObjects) PutObjectPart(bucket, object, uploadID string, partID int, d
 
 	// Hold the lock so that two parallel complete-multipart-uploads
 	// do not leave a stale uploads.json behind.
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
+	objectMPartPathLock := fs.nsMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
 	if err := objectMPartPathLock.GetLock(globalOperationTimeout); err != nil {
 		return pi, err
 	}
@@ -557,7 +574,7 @@ func (fs fsObjects) PutObjectPart(bucket, object, uploadID string, partID int, d
 	partPath := pathJoin(bucket, object, uploadID, partSuffix)
 	// Lock the part so that another part upload with same part-number gets blocked
 	// while the part is getting appended in the background.
-	partLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, partPath)
+	partLock := fs.nsMutex.NewNSLock(minioMetaMultipartBucket, partPath)
 	if err = partLock.GetLock(globalOperationTimeout); err != nil {
 		return pi, err
 	}
@@ -689,7 +706,7 @@ func (fs fsObjects) ListObjectParts(bucket, object, uploadID string, partNumberM
 
 	// Hold the lock so that two parallel complete-multipart-uploads
 	// do not leave a stale uploads.json behind.
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
+	objectMPartPathLock := fs.nsMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
 	if err := objectMPartPathLock.GetRLock(globalListingTimeout); err != nil {
 		return lpi, errors.Trace(err)
 	}
@@ -714,6 +731,12 @@ func (fs fsObjects) CompleteMultipartUpload(bucket string, object string, upload
 		return oi, err
 	}
 
+	// Hold write lock on the object.
+	destLock := fs.nsMutex.NewNSLock(bucket, object)
+	if err := destLock.GetLock(globalObjectTimeout); err != nil {
+		return oi, err
+	}
+	defer destLock.Unlock()
 	// Check if an object is present as one of the parent dir.
 	if fs.parentDirIsObject(bucket, pathutil.Dir(object)) {
 		return oi, toObjectErr(errors.Trace(errFileAccessDenied), bucket, object)
@@ -734,7 +757,7 @@ func (fs fsObjects) CompleteMultipartUpload(bucket string, object string, upload
 
 	// Hold the lock so that two parallel complete-multipart-uploads
 	// do not leave a stale uploads.json behind.
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
+	objectMPartPathLock := fs.nsMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
 	if err = objectMPartPathLock.GetLock(globalOperationTimeout); err != nil {
 		return oi, err
 	}
@@ -974,7 +997,7 @@ func (fs fsObjects) AbortMultipartUpload(bucket, object, uploadID string) error
 
 	// Hold the lock so that two parallel complete-multipart-uploads
 	// do not leave a stale uploads.json behind.
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+	objectMPartPathLock := fs.nsMutex.NewNSLock(minioMetaMultipartBucket,
 		pathJoin(bucket, object))
 	if err := objectMPartPathLock.GetLock(globalOperationTimeout); err != nil {
 		return err

cmd/fs-v1.go

@@ -26,6 +26,7 @@ import (
 	"path/filepath"
 	"sort"
 	"syscall"
+	"time"
 
 	"github.com/minio/minio/pkg/errors"
 	"github.com/minio/minio/pkg/hash"
@@ -52,6 +53,9 @@ type fsObjects struct {
 
 	// To manage the appendRoutine go0routines
 	bgAppend *backgroundAppend
+
+	// name space mutex for object layer
+	nsMutex *nsLockMap
 }
 
 // Initializes meta volume on all the fs path.
@@ -138,6 +142,7 @@ func newFSObjectLayer(fsPath string) (ObjectLayer, error) {
 		bgAppend: &backgroundAppend{
 			infoMap: make(map[string]bgAppendPartsInfo),
 		},
+		nsMutex: newNSLock(false),
 	}
 
 	// Once the filesystem has initialized hold the read lock for
@@ -183,6 +188,18 @@ func (fs fsObjects) StorageInfo() StorageInfo {
 	return storageInfo
 }
 
+// Locking operations
+
+// List namespace locks held in object layer
+func (fs fsObjects) ListLocks(bucket, prefix string, duration time.Duration) ([]VolumeLockInfo, error) {
+	return []VolumeLockInfo{}, NotImplemented{}
+}
+
+// Clear namespace locks held in object layer
+func (fs fsObjects) ClearLocks([]VolumeLockInfo) error {
+	return NotImplemented{}
+}
+
 /// Bucket operations
 
 // getBucketDir - will convert incoming bucket names to
@@ -213,6 +230,11 @@ func (fs fsObjects) statBucketDir(bucket string) (os.FileInfo, error) {
 // MakeBucket - create a new bucket, returns if it
 // already exists.
 func (fs fsObjects) MakeBucketWithLocation(bucket, location string) error {
+	bucketLock := fs.nsMutex.NewNSLock(bucket, "")
+	if err := bucketLock.GetLock(globalObjectTimeout); err != nil {
+		return err
+	}
+	defer bucketLock.Unlock()
 	bucketDir, err := fs.getBucketDir(bucket)
 	if err != nil {
 		return toObjectErr(err, bucket)
@@ -313,7 +335,29 @@ func (fs fsObjects) DeleteBucket(bucket string) error {
 // CopyObject - copy object source object to destination object.
 // if source object and destination object are same we only
 // update metadata.
-func (fs fsObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string, metadata map[string]string) (oi ObjectInfo, e error) {
+func (fs fsObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string, metadata map[string]string, srcEtag string) (oi ObjectInfo, e error) {
+	cpSrcDstSame := srcBucket == dstBucket && srcObject == dstObject
+	// Hold write lock on destination since in both cases
+	// - if source and destination are same
+	// - if source and destination are different
+	// it is the sole mutating state.
+	objectDWLock := fs.nsMutex.NewNSLock(dstBucket, dstObject)
+	if err := objectDWLock.GetLock(globalObjectTimeout); err != nil {
+		return oi, err
+	}
+	defer objectDWLock.Unlock()
+	// if source and destination are different, we have to hold
+	// additional read lock as well to protect against writes on
+	// source.
+	if !cpSrcDstSame {
+		// Hold read locks on source object only if we are
+		// going to read data from source object.
+		objectSRLock := fs.nsMutex.NewNSLock(srcBucket, srcObject)
+		if err := objectSRLock.GetRLock(globalObjectTimeout); err != nil {
+			return oi, err
+		}
+		defer objectSRLock.RUnlock()
+	}
 	if _, err := fs.statBucketDir(srcBucket); err != nil {
 		return oi, toObjectErr(err, srcBucket)
 	}
@@ -323,6 +367,15 @@ func (fs fsObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string
 	if err != nil {
 		return oi, toObjectErr(err, srcBucket, srcObject)
 	}
+	if srcEtag != "" {
+		etag, perr := fs.getObjectETag(srcBucket, srcObject)
+		if perr != nil {
+			return oi, toObjectErr(perr, srcBucket, srcObject)
+		}
+		if etag != srcEtag {
+			return oi, toObjectErr(errors.Trace(InvalidETag{}), srcBucket, srcObject)
+		}
+	}
 
 	// Check if this request is only metadata update.
 	cpMetadataOnly := isStringEqual(pathJoin(srcBucket, srcObject), pathJoin(dstBucket, dstObject))
@@ -355,7 +408,7 @@ func (fs fsObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string
 
 	go func() {
 		var startOffset int64 // Read the whole file.
-		if gerr := fs.GetObject(srcBucket, srcObject, startOffset, length, pipeWriter); gerr != nil {
+		if gerr := fs.getObject(srcBucket, srcObject, startOffset, length, pipeWriter, ""); gerr != nil {
 			errorIf(gerr, "Unable to read %s/%s.", srcBucket, srcObject)
 			pipeWriter.CloseWithError(gerr)
 			return
@@ -368,7 +421,7 @@ func (fs fsObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string
 		return oi, toObjectErr(err, dstBucket, dstObject)
 	}
 
-	objInfo, err := fs.PutObject(dstBucket, dstObject, hashReader, metadata)
+	objInfo, err := fs.putObject(dstBucket, dstObject, hashReader, metadata)
 	if err != nil {
 		return oi, toObjectErr(err, dstBucket, dstObject)
 	}
@@ -385,11 +438,22 @@ func (fs fsObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string
 //
 // startOffset indicates the starting read location of the object.
 // length indicates the total length of the object.
-func (fs fsObjects) GetObject(bucket, object string, offset int64, length int64, writer io.Writer) (err error) {
+func (fs fsObjects) GetObject(bucket, object string, offset int64, length int64, writer io.Writer, etag string) (err error) {
 	if err = checkBucketAndObjectNamesFS(bucket, object); err != nil {
 		return err
 	}
 
+	// Lock the object before reading.
+	objectLock := fs.nsMutex.NewNSLock(bucket, object)
+	if err := objectLock.GetRLock(globalObjectTimeout); err != nil {
+		return err
+	}
+	defer objectLock.RUnlock()
+	return fs.getObject(bucket, object, offset, length, writer, etag)
+}
+
+// getObject - wrapper for GetObject
+func (fs fsObjects) getObject(bucket, object string, offset int64, length int64, writer io.Writer, etag string) (err error) {
 	if _, err = fs.statBucketDir(bucket); err != nil {
 		return toObjectErr(err, bucket)
 	}
@@ -419,6 +483,15 @@ func (fs fsObjects) GetObject(bucket, object string, offset int64, length int64,
 		defer fs.rwPool.Close(fsMetaPath)
 	}
 
+	if etag != "" {
+		objEtag, perr := fs.getObjectETag(bucket, object)
+		if perr != nil {
+			return toObjectErr(errors.Trace(perr), bucket, object)
+		}
+		if objEtag != etag {
+			return toObjectErr(errors.Trace(InvalidETag{}), bucket, object)
+		}
+	}
 	// Read the object, doesn't exist returns an s3 compatible error.
 	fsObjPath := pathJoin(fs.fsPath, bucket, object)
 	reader, size, err := fsOpenFile(fsObjPath, offset)
@@ -516,6 +589,13 @@ func checkBucketAndObjectNamesFS(bucket, object string) error {
 
 // GetObjectInfo - reads object metadata and replies back ObjectInfo.
 func (fs fsObjects) GetObjectInfo(bucket, object string) (oi ObjectInfo, e error) {
+	// Lock the object before reading.
+	objectLock := fs.nsMutex.NewNSLock(bucket, object)
+	if err := objectLock.GetRLock(globalObjectTimeout); err != nil {
+		return oi, err
+	}
+	defer objectLock.RUnlock()
+
 	if err := checkBucketAndObjectNamesFS(bucket, object); err != nil {
 		return oi, err
 	}
@@ -552,11 +632,21 @@ func (fs fsObjects) parentDirIsObject(bucket, parent string) bool {
 // Additionally writes `fs.json` which carries the necessary metadata
 // for future object operations.
 func (fs fsObjects) PutObject(bucket string, object string, data *hash.Reader, metadata map[string]string) (objInfo ObjectInfo, retErr error) {
+	// Lock the object.
+	objectLock := fs.nsMutex.NewNSLock(bucket, object)
+	if err := objectLock.GetLock(globalObjectTimeout); err != nil {
+		return objInfo, err
+	}
+	defer objectLock.Unlock()
+	return fs.putObject(bucket, object, data, metadata)
+}
+
+// putObject - wrapper for PutObject
+func (fs fsObjects) putObject(bucket string, object string, data *hash.Reader, metadata map[string]string) (objInfo ObjectInfo, retErr error) {
 	// No metadata is set, allocate a new one.
 	if metadata == nil {
 		metadata = make(map[string]string)
 	}
-
 	var err error
 
 	// Validate if bucket name is valid and exists.
@@ -677,6 +767,13 @@ func (fs fsObjects) PutObject(bucket string, object string, data *hash.Reader, m
 // DeleteObject - deletes an object from a bucket, this operation is destructive
 // and there are no rollbacks supported.
 func (fs fsObjects) DeleteObject(bucket, object string) error {
+	// Acquire a write lock before deleting the object.
+	objectLock := fs.nsMutex.NewNSLock(bucket, object)
+	if err := objectLock.GetLock(globalOperationTimeout); err != nil {
+		return err
+	}
+	defer objectLock.Unlock()
+
 	if err := checkBucketAndObjectNamesFS(bucket, object); err != nil {
 		return err
 	}
@@ -825,7 +922,7 @@ func (fs fsObjects) ListObjects(bucket, prefix, marker, delimiter string, maxKey
 	// Convert entry to ObjectInfo
 	entryToObjectInfo := func(entry string) (objInfo ObjectInfo, err error) {
 		// Protect the entry from concurrent deletes, or renames.
-		objectLock := globalNSMutex.NewNSLock(bucket, entry)
+		objectLock := fs.nsMutex.NewNSLock(bucket, entry)
 		if err = objectLock.GetRLock(globalListingTimeout); err != nil {
 			return ObjectInfo{}, err
 		}

cmd/gateway-handlers.go

@@ -128,7 +128,7 @@ func (api gatewayAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Re
 	setHeadGetRespHeaders(w, r.URL.Query())
 	httpWriter := ioutil.WriteOnClose(w)
 	// Reads the object at startOffset and writes to mw.
-	if err = getObject(bucket, object, startOffset, length, httpWriter); err != nil {
+	if err = getObject(bucket, object, startOffset, length, httpWriter, objInfo.ETag); err != nil {
 		errorIf(err, "Unable to write to client.")
 		if !httpWriter.HasWritten() {
 			// Error response only if no data has been written to client yet. i.e if
@@ -250,14 +250,6 @@ func (api gatewayAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Re
 		}
 	}
 
-	// Lock the object.
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
-	if objectLock.GetLock(globalOperationTimeout) != nil {
-		writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-		return
-	}
-	defer objectLock.Unlock()
-
 	var (
 		// Make sure we hex encode md5sum here.
 		md5hex    = hex.EncodeToString(md5Bytes)

cmd/gateway-router.go

@@ -45,7 +45,7 @@ type Gateway interface {
 type GatewayLayer interface {
 	ObjectLayer
 
-	AnonGetObject(bucket, object string, startOffset int64, length int64, writer io.Writer) (err error)
+	AnonGetObject(bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) (err error)
 	AnonGetObjectInfo(bucket, object string) (objInfo ObjectInfo, err error)
 
 	AnonPutObject(bucket string, object string, data *hash.Reader, metadata map[string]string) (ObjectInfo, error)

cmd/gateway-unsupported.go

@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"io"
+	"time"
 
 	"github.com/minio/minio-go/pkg/policy"
 	"github.com/minio/minio/pkg/errors"
@@ -38,7 +39,7 @@ func (a GatewayUnsupported) NewMultipartUpload(bucket string, object string, met
 }
 
 // CopyObjectPart copy part of object to other bucket and object
-func (a GatewayUnsupported) CopyObjectPart(srcBucket string, srcObject string, destBucket string, destObject string, uploadID string, partID int, startOffset int64, length int64, metadata map[string]string) (pi PartInfo, err error) {
+func (a GatewayUnsupported) CopyObjectPart(srcBucket string, srcObject string, destBucket string, destObject string, uploadID string, partID int, startOffset int64, length int64, metadata map[string]string, srcEtag string) (pi PartInfo, err error) {
 	return pi, errors.Trace(NotImplemented{})
 }
 
@@ -132,7 +133,7 @@ func (a GatewayUnsupported) AnonPutObject(bucket, object string, data *hash.Read
 }
 
 // AnonGetObject downloads object anonymously.
-func (a GatewayUnsupported) AnonGetObject(bucket, object string, startOffset int64, length int64, writer io.Writer) (err error) {
+func (a GatewayUnsupported) AnonGetObject(bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) (err error) {
 	return errors.Trace(NotImplemented{})
 }
 
@@ -143,6 +144,18 @@ func (a GatewayUnsupported) AnonGetObjectInfo(bucket, object string) (objInfo Ob
 
 // CopyObject copies a blob from source container to destination container.
 func (a GatewayUnsupported) CopyObject(srcBucket string, srcObject string, destBucket string, destObject string,
-	metadata map[string]string) (objInfo ObjectInfo, err error) {
+	metadata map[string]string, srcEtag string) (objInfo ObjectInfo, err error) {
 	return objInfo, errors.Trace(NotImplemented{})
 }
+
+// Locking operations
+
+// ListLocks lists namespace locks held in object layer
+func (a GatewayUnsupported) ListLocks(bucket, prefix string, duration time.Duration) ([]VolumeLockInfo, error) {
+	return []VolumeLockInfo{}, errors.Trace(NotImplemented{})
+}
+
+// ClearLocks clears namespace locks held in object layer
+func (a GatewayUnsupported) ClearLocks([]VolumeLockInfo) error {
+	return errors.Trace(NotImplemented{})
+}

cmd/gateway/azure/gateway-azure-anonymous.go

@@ -145,7 +145,7 @@ func (a *azureObjects) AnonGetBucketInfo(bucket string) (bucketInfo minio.Bucket
 
 // AnonGetObject - SendGET request without authentication.
 // This is needed when clients send GET requests on objects that can be downloaded without auth.
-func (a *azureObjects) AnonGetObject(bucket, object string, startOffset int64, length int64, writer io.Writer) (err error) {
+func (a *azureObjects) AnonGetObject(bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) (err error) {
 	h := make(http.Header)
 	if length > 0 && startOffset > 0 {
 		h.Add("Range", fmt.Sprintf("bytes=%d-%d", startOffset, startOffset+length-1))

cmd/gateway/azure/gateway-azure.go

@@ -554,7 +554,7 @@ func (a *azureObjects) ListObjectsV2(bucket, prefix, continuationToken, delimite
 //
 // startOffset indicates the starting read location of the object.
 // length indicates the total length of the object.
-func (a *azureObjects) GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer) error {
+func (a *azureObjects) GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	// startOffset cannot be negative.
 	if startOffset < 0 {
 		return azureToObjectError(errors.Trace(minio.InvalidRange{}), bucket, object)
@@ -621,7 +621,7 @@ func (a *azureObjects) PutObject(bucket, object string, data *hash.Reader, metad
 
 // CopyObject - Copies a blob from source container to destination container.
 // Uses Azure equivalent CopyBlob API.
-func (a *azureObjects) CopyObject(srcBucket, srcObject, destBucket, destObject string, metadata map[string]string) (objInfo minio.ObjectInfo, err error) {
+func (a *azureObjects) CopyObject(srcBucket, srcObject, destBucket, destObject string, metadata map[string]string, srcEtag string) (objInfo minio.ObjectInfo, err error) {
 	srcBlobURL := a.client.GetContainerReference(srcBucket).GetBlobReference(srcObject).GetURL()
 	destBlob := a.client.GetContainerReference(destBucket).GetBlobReference(destObject)
 	azureMeta, props, err := s3MetaToAzureProperties(metadata)

cmd/gateway/b2/gateway-b2-anonymous.go

@@ -43,7 +43,7 @@ func mkRange(offset, size int64) string {
 
 // AnonGetObject - performs a plain http GET request on a public resource,
 // fails if the resource is not public.
-func (l *b2Objects) AnonGetObject(bucket string, object string, startOffset int64, length int64, writer io.Writer) error {
+func (l *b2Objects) AnonGetObject(bucket string, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	uri := fmt.Sprintf("%s/file/%s/%s", l.b2Client.DownloadURI, bucket, object)
 	req, err := http.NewRequest("GET", uri, nil)
 	if err != nil {

cmd/gateway/b2/gateway-b2.go

@@ -379,7 +379,7 @@ func (l *b2Objects) ListObjectsV2(bucket, prefix, continuationToken, delimiter s
 //
 // startOffset indicates the starting read location of the object.
 // length indicates the total length of the object.
-func (l *b2Objects) GetObject(bucket string, object string, startOffset int64, length int64, writer io.Writer) error {
+func (l *b2Objects) GetObject(bucket string, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	bkt, err := l.Bucket(bucket)
 	if err != nil {
 		return err
@@ -523,7 +523,7 @@ func (l *b2Objects) PutObject(bucket string, object string, data *h2.Reader, met
 
 // CopyObject copies a blob from source container to destination container.
 func (l *b2Objects) CopyObject(srcBucket string, srcObject string, dstBucket string,
-	dstObject string, metadata map[string]string) (objInfo minio.ObjectInfo, err error) {
+	dstObject string, metadata map[string]string, srcEtag string) (objInfo minio.ObjectInfo, err error) {
 	return objInfo, errors.Trace(minio.NotImplemented{})
 }
 

cmd/gateway/gcs/gateway-gcs-anonymous.go

@@ -33,7 +33,7 @@ func toGCSPublicURL(bucket, object string) string {
 }
 
 // AnonGetObject - Get object anonymously
-func (l *gcsGateway) AnonGetObject(bucket string, object string, startOffset int64, length int64, writer io.Writer) error {
+func (l *gcsGateway) AnonGetObject(bucket string, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	req, err := http.NewRequest("GET", toGCSPublicURL(bucket, object), nil)
 	if err != nil {
 		return gcsToObjectError(errors.Trace(err), bucket, object)

cmd/gateway/gcs/gateway-gcs.go

@@ -725,7 +725,7 @@ func (l *gcsGateway) ListObjectsV2(bucket, prefix, continuationToken, delimiter
 //
 // startOffset indicates the starting read location of the object.
 // length indicates the total length of the object.
-func (l *gcsGateway) GetObject(bucket string, key string, startOffset int64, length int64, writer io.Writer) error {
+func (l *gcsGateway) GetObject(bucket string, key string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	// if we want to mimic S3 behavior exactly, we need to verify if bucket exists first,
 	// otherwise gcs will just return object not exist in case of non-existing bucket
 	if _, err := l.client.Bucket(bucket).Attrs(l.ctx); err != nil {
@@ -813,7 +813,7 @@ func (l *gcsGateway) PutObject(bucket string, key string, data *hash.Reader, met
 
 // CopyObject - Copies a blob from source container to destination container.
 func (l *gcsGateway) CopyObject(srcBucket string, srcObject string, destBucket string, destObject string,
-	metadata map[string]string) (minio.ObjectInfo, error) {
+	metadata map[string]string, srcEtag string) (minio.ObjectInfo, error) {
 
 	src := l.client.Bucket(srcBucket).Object(srcObject)
 	dst := l.client.Bucket(destBucket).Object(destObject)

cmd/gateway/manta/gateway-manta.go

@@ -468,7 +468,7 @@ func (t *tritonObjects) ListObjectsV2(bucket, prefix, continuationToken, delimit
 // indicates the total length of the object.
 //
 // https://apidocs.joyent.com/manta/api.html#GetObject
-func (t *tritonObjects) GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer) error {
+func (t *tritonObjects) GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	// Start offset cannot be negative.
 	if startOffset < 0 {
 		return errors.Trace(fmt.Errorf("Unexpected error"))
@@ -568,7 +568,7 @@ func (t *tritonObjects) PutObject(bucket, object string, data *hash.Reader, meta
 // Uses Manta Snaplinks API.
 //
 // https://apidocs.joyent.com/manta/api.html#PutSnapLink
-func (t *tritonObjects) CopyObject(srcBucket, srcObject, destBucket, destObject string, metadata map[string]string) (objInfo minio.ObjectInfo, err error) {
+func (t *tritonObjects) CopyObject(srcBucket, srcObject, destBucket, destObject string, metadata map[string]string, srcEtag string) (objInfo minio.ObjectInfo, err error) {
 	ctx := context.Background()
 	if err = t.client.SnapLinks().Put(ctx, &storage.PutSnapLinkInput{
 		SourcePath: path.Join(mantaRoot, srcBucket, srcObject),

cmd/gateway/oss/gateway-oss-anonymous.go

@@ -29,8 +29,8 @@ func (l *ossObjects) AnonPutObject(bucket, object string, data *hash.Reader, met
 }
 
 // AnonGetObject - Get object anonymously
-func (l *ossObjects) AnonGetObject(bucket, key string, startOffset, length int64, writer io.Writer) error {
+func (l *ossObjects) AnonGetObject(bucket, key string, startOffset, length int64, writer io.Writer, etag string) error {
-	return ossGetObject(l.anonClient, bucket, key, startOffset, length, writer)
+	return ossGetObject(l.anonClient, bucket, key, startOffset, length, writer, etag)
 }
 
 // AnonGetObjectInfo - Get object info anonymously

cmd/gateway/oss/gateway-oss.go

@@ -506,7 +506,7 @@ func (l *ossObjects) ListObjectsV2(bucket, prefix, continuationToken, delimiter
 //
 // startOffset indicates the starting read location of the object.
 // length indicates the total length of the object.
-func ossGetObject(client *oss.Client, bucket, key string, startOffset, length int64, writer io.Writer) error {
+func ossGetObject(client *oss.Client, bucket, key string, startOffset, length int64, writer io.Writer, etag string) error {
 	if length < 0 && length != -1 {
 		return ossToObjectError(errors.Trace(fmt.Errorf("Invalid argument")), bucket, key)
 	}
@@ -539,8 +539,8 @@ func ossGetObject(client *oss.Client, bucket, key string, startOffset, length in
 //
 // startOffset indicates the starting read location of the object.
 // length indicates the total length of the object.
-func (l *ossObjects) GetObject(bucket, key string, startOffset, length int64, writer io.Writer) error {
+func (l *ossObjects) GetObject(bucket, key string, startOffset, length int64, writer io.Writer, etag string) error {
-	return ossGetObject(l.Client, bucket, key, startOffset, length, writer)
+	return ossGetObject(l.Client, bucket, key, startOffset, length, writer, etag)
 }
 
 func translatePlainError(err error) error {
@@ -618,7 +618,7 @@ func (l *ossObjects) PutObject(bucket, object string, data *hash.Reader, metadat
 }
 
 // CopyObject copies an object from source bucket to a destination bucket.
-func (l *ossObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string, metadata map[string]string) (objInfo minio.ObjectInfo, err error) {
+func (l *ossObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string, metadata map[string]string, srcEtag string) (objInfo minio.ObjectInfo, err error) {
 	bkt, err := l.Client.Bucket(srcBucket)
 	if err != nil {
 		return objInfo, ossToObjectError(errors.Trace(err), srcBucket, srcObject)
@@ -804,7 +804,7 @@ func ossListObjectParts(client *oss.Client, bucket, object, uploadID string, par
 // CopyObjectPart creates a part in a multipart upload by copying
 // existing object or a part of it.
 func (l *ossObjects) CopyObjectPart(srcBucket, srcObject, destBucket, destObject, uploadID string,
-	partID int, startOffset, length int64, metadata map[string]string) (p minio.PartInfo, err error) {
+	partID int, startOffset, length int64, metadata map[string]string, srcEtag string) (p minio.PartInfo, err error) {
 
 	bkt, err := l.Client.Bucket(destBucket)
 	if err != nil {

cmd/gateway/s3/gateway-s3-anonymous.go

@@ -37,7 +37,7 @@ func (l *s3Objects) AnonPutObject(bucket string, object string, data *hash.Reade
 }
 
 // AnonGetObject - Get object anonymously
-func (l *s3Objects) AnonGetObject(bucket string, key string, startOffset int64, length int64, writer io.Writer) error {
+func (l *s3Objects) AnonGetObject(bucket string, key string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	opts := miniogo.GetObjectOptions{}
 	if err := opts.SetRange(startOffset, startOffset+length-1); err != nil {
 		return minio.ErrorRespToObjectError(errors.Trace(err), bucket, key)

cmd/gateway/s3/gateway-s3.go

@@ -254,7 +254,7 @@ func (l *s3Objects) ListObjectsV2(bucket, prefix, continuationToken, delimiter s
 //
 // startOffset indicates the starting read location of the object.
 // length indicates the total length of the object.
-func (l *s3Objects) GetObject(bucket string, key string, startOffset int64, length int64, writer io.Writer) error {
+func (l *s3Objects) GetObject(bucket string, key string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	if length < 0 && length != -1 {
 		return minio.ErrorRespToObjectError(errors.Trace(minio.InvalidRange{}), bucket, key)
 	}
@@ -298,7 +298,7 @@ func (l *s3Objects) PutObject(bucket string, object string, data *hash.Reader, m
 }
 
 // CopyObject copies an object from source bucket to a destination bucket.
-func (l *s3Objects) CopyObject(srcBucket string, srcObject string, dstBucket string, dstObject string, metadata map[string]string) (objInfo minio.ObjectInfo, err error) {
+func (l *s3Objects) CopyObject(srcBucket string, srcObject string, dstBucket string, dstObject string, metadata map[string]string, srcEtag string) (objInfo minio.ObjectInfo, err error) {
 	// Set this header such that following CopyObject() always sets the right metadata on the destination.
 	// metadata input is already a trickled down value from interpreting x-amz-metadata-directive at
 	// handler layer. So what we have right now is supposed to be applied on the destination object anyways.
@@ -354,7 +354,7 @@ func (l *s3Objects) PutObjectPart(bucket string, object string, uploadID string,
 // CopyObjectPart creates a part in a multipart upload by copying
 // existing object or a part of it.
 func (l *s3Objects) CopyObjectPart(srcBucket, srcObject, destBucket, destObject, uploadID string,
-	partID int, startOffset, length int64, metadata map[string]string) (p minio.PartInfo, err error) {
+	partID int, startOffset, length int64, metadata map[string]string, srcEtag string) (p minio.PartInfo, err error) {
 
 	completePart, err := l.Client.CopyObjectPart(srcBucket, srcObject, destBucket, destObject,
 		uploadID, partID, startOffset, length, metadata)

cmd/gateway/sia/gateway-sia.go

@@ -410,7 +410,7 @@ func (s *siaObjects) ListObjects(bucket string, prefix string, marker string, de
 	return loi, nil
 }
 
-func (s *siaObjects) GetObject(bucket string, object string, startOffset int64, length int64, writer io.Writer) error {
+func (s *siaObjects) GetObject(bucket string, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
 	dstFile := path.Join(s.TempDir, minio.MustGetUUID())
 	defer os.Remove(dstFile)
 

cmd/lockinfo-handlers.go

@@ -66,47 +66,6 @@ type OpsLockState struct {
 
 // listLocksInfo - Fetches locks held on bucket, matching prefix held for longer than duration.
 func listLocksInfo(bucket, prefix string, duration time.Duration) []VolumeLockInfo {
-	globalNSMutex.lockMapMutex.Lock()
+	locksInfo, _ := newObjectLayerFn().ListLocks(bucket, prefix, duration)
-	defer globalNSMutex.lockMapMutex.Unlock()
+	return locksInfo
-
-	// Fetch current time once instead of fetching system time for every lock.
-	timeNow := UTCNow()
-	volumeLocks := []VolumeLockInfo{}
-
-	for param, debugLock := range globalNSMutex.debugLockMap {
-		if param.volume != bucket {
-			continue
-		}
-		// N B empty prefix matches all param.path.
-		if !hasPrefix(param.path, prefix) {
-			continue
-		}
-
-		volLockInfo := VolumeLockInfo{
-			Bucket:                param.volume,
-			Object:                param.path,
-			LocksOnObject:         debugLock.counters.total,
-			TotalBlockedLocks:     debugLock.counters.blocked,
-			LocksAcquiredOnObject: debugLock.counters.granted,
-		}
-		// Filter locks that are held on bucket, prefix.
-		for opsID, lockInfo := range debugLock.lockInfo {
-			// filter locks that were held for longer than duration.
-			elapsed := timeNow.Sub(lockInfo.since)
-			if elapsed < duration {
-				continue
-			}
-			// Add locks that are held for longer than duration.
-			volLockInfo.LockDetailsOnObject = append(volLockInfo.LockDetailsOnObject,
-				OpsLockState{
-					OperationID: opsID,
-					LockSource:  lockInfo.lockSource,
-					LockType:    lockInfo.lType,
-					Status:      lockInfo.status,
-					Since:       lockInfo.since,
-				})
-			volumeLocks = append(volumeLocks, volLockInfo)
-		}
-	}
-	return volumeLocks
 }

cmd/lockinfo-handlers_test.go

@@ -28,11 +28,22 @@ func TestListLocksInfo(t *testing.T) {
 	// instrumentation information.
 	isDistXL := false
 	initNSLock(isDistXL)
+	objAPI := newObjectLayerFn()
+	if objAPI == nil {
+		t.Errorf("Failed to initialize object layer")
+	}
+	var nsMutex *nsLockMap
+	switch objAPI.(type) {
+	case *fsObjects:
+		nsMutex = objAPI.(*fsObjects).nsMutex
+	case *xlObjects:
+		nsMutex = objAPI.(*xlObjects).nsMutex
+	}
 
 	// Acquire a few locks to populate lock instrumentation.
 	// Take 10 read locks on bucket1/prefix1/obj1
 	for i := 0; i < 10; i++ {
-		readLk := globalNSMutex.NewNSLock("bucket1", "prefix1/obj1")
+		readLk := nsMutex.NewNSLock("bucket1", "prefix1/obj1")
 		if readLk.GetRLock(newDynamicTimeout(60*time.Second, time.Second)) != nil {
 			t.Errorf("Failed to get read lock on iteration %d", i)
 		}
@@ -40,7 +51,7 @@ func TestListLocksInfo(t *testing.T) {
 
 	// Take write locks on bucket1/prefix/obj{11..19}
 	for i := 0; i < 10; i++ {
-		wrLk := globalNSMutex.NewNSLock("bucket1", fmt.Sprintf("prefix1/obj%d", 10+i))
+		wrLk := nsMutex.NewNSLock("bucket1", fmt.Sprintf("prefix1/obj%d", 10+i))
 		if wrLk.GetLock(newDynamicTimeout(60*time.Second, time.Second)) != nil {
 			t.Errorf("Failed to get write lock on iteration %d", i)
 		}

cmd/namespace-lock.go

@@ -92,9 +92,9 @@ func newDsyncNodes(endpoints EndpointList) (clnts []dsync.NetLocker, myNode int)
 	return clnts, myNode
 }
 
-// initNSLock - initialize name space lock map.
+// newNSLock - return a new name space lock map.
-func initNSLock(isDistXL bool) {
+func newNSLock(isDistXL bool) *nsLockMap {
-	globalNSMutex = &nsLockMap{
+	nsMutex := nsLockMap{
 		isDistXL: isDistXL,
 		lockMap:  make(map[nsParam]*nsLock),
 		counters: &lockStat{},
@@ -102,7 +102,13 @@ func initNSLock(isDistXL bool) {
 
 	// Initialize nsLockMap with entry for instrumentation information.
 	// Entries of <volume,path> -> stateInfo of locks
-	globalNSMutex.debugLockMap = make(map[nsParam]*debugLockInfoPerVolumePath)
+	nsMutex.debugLockMap = make(map[nsParam]*debugLockInfoPerVolumePath)
+	return &nsMutex
+}
+
+// initNSLock - initialize name space lock map.
+func initNSLock(isDistXL bool) {
+	globalNSMutex = newNSLock(isDistXL)
 }
 
 // nsParam - carries name space resource.

cmd/object-api-errors.go

@@ -349,6 +349,13 @@ func (e PartTooBig) Error() string {
 	return "Part size bigger than the allowed limit"
 }
 
+// InvalidETag error returned when the etag has changed on disk
+type InvalidETag struct{}
+
+func (e InvalidETag) Error() string {
+	return "etag of the object has changed"
+}
+
 // NotImplemented If a feature is not implemented
 type NotImplemented struct{}
 

cmd/object-api-getobject_test.go

@@ -152,7 +152,7 @@ func testGetObject(obj ObjectLayer, instanceType string, t TestErrHandler) {
 	}
 
 	for i, testCase := range testCases {
-		err = obj.GetObject(testCase.bucketName, testCase.objectName, testCase.startOffset, testCase.length, testCase.writer)
+		err = obj.GetObject(testCase.bucketName, testCase.objectName, testCase.startOffset, testCase.length, testCase.writer, "")
 		if err != nil && testCase.shouldPass {
 			t.Errorf("Test %d: %s:  Expected to pass, but failed with: <ERROR> %s", i+1, instanceType, err.Error())
 		}
@@ -262,7 +262,7 @@ func testGetObjectPermissionDenied(obj ObjectLayer, instanceType string, disks [
 			}
 		}
 
-		err = obj.GetObject(testCase.bucketName, testCase.objectName, testCase.startOffset, testCase.length, testCase.writer)
+		err = obj.GetObject(testCase.bucketName, testCase.objectName, testCase.startOffset, testCase.length, testCase.writer, "")
 		if err != nil && testCase.shouldPass {
 			t.Errorf("Test %d: %s:  Expected to pass, but failed with: <ERROR> %s", i+1, instanceType, err.Error())
 		}
@@ -423,7 +423,7 @@ func testGetObjectDiskNotFound(obj ObjectLayer, instanceType string, disks []str
 	}
 
 	for i, testCase := range testCases {
-		err = obj.GetObject(testCase.bucketName, testCase.objectName, testCase.startOffset, testCase.length, testCase.writer)
+		err = obj.GetObject(testCase.bucketName, testCase.objectName, testCase.startOffset, testCase.length, testCase.writer, "")
 		if err != nil && testCase.shouldPass {
 			t.Errorf("Test %d: %s:  Expected to pass, but failed with: <ERROR> %s", i+1, instanceType, err.Error())
 		}

cmd/object-api-interface.go

@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"io"
+	"time"
 
 	"github.com/minio/minio/pkg/hash"
 )
@@ -36,16 +37,16 @@ type ObjectLayer interface {
 	ListObjects(bucket, prefix, marker, delimiter string, maxKeys int) (result ListObjectsInfo, err error)
 
 	// Object operations.
-	GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer) (err error)
+	GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) (err error)
 	GetObjectInfo(bucket, object string) (objInfo ObjectInfo, err error)
 	PutObject(bucket, object string, data *hash.Reader, metadata map[string]string) (objInfo ObjectInfo, err error)
-	CopyObject(srcBucket, srcObject, destBucket, destObject string, metadata map[string]string) (objInfo ObjectInfo, err error)
+	CopyObject(srcBucket, srcObject, destBucket, destObject string, metadata map[string]string, srcETag string) (objInfo ObjectInfo, err error)
 	DeleteObject(bucket, object string) error
 
 	// Multipart operations.
 	ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarker, delimiter string, maxUploads int) (result ListMultipartsInfo, err error)
 	NewMultipartUpload(bucket, object string, metadata map[string]string) (uploadID string, err error)
-	CopyObjectPart(srcBucket, srcObject, destBucket, destObject string, uploadID string, partID int, startOffset int64, length int64, metadata map[string]string) (info PartInfo, err error)
+	CopyObjectPart(srcBucket, srcObject, destBucket, destObject string, uploadID string, partID int, startOffset int64, length int64, metadata map[string]string, srcEtag string) (info PartInfo, err error)
 	PutObjectPart(bucket, object, uploadID string, partID int, data *hash.Reader) (info PartInfo, err error)
 	ListObjectParts(bucket, object, uploadID string, partNumberMarker int, maxParts int) (result ListPartsInfo, err error)
 	AbortMultipartUpload(bucket, object, uploadID string) error
@@ -58,4 +59,8 @@ type ObjectLayer interface {
 	ListObjectsHeal(bucket, prefix, marker, delimiter string, maxKeys int) (ListObjectsInfo, error)
 	ListUploadsHeal(bucket, prefix, marker, uploadIDMarker,
 		delimiter string, maxUploads int) (ListMultipartsInfo, error)
+
+	// Locking operations
+	ListLocks(bucket, prefix string, duration time.Duration) ([]VolumeLockInfo, error)
+	ClearLocks([]VolumeLockInfo) error
 }

cmd/object-api-multipart-common.go

@@ -169,7 +169,7 @@ func writeUploadJSON(u *uploadsV1, uploadsPath, tmpPath string, disk StorageAPI)
 }
 
 // listMultipartUploadIDs - list all the upload ids from a marker up to 'count'.
-func listMultipartUploadIDs(bucketName, objectName, uploadIDMarker string, count int, disk StorageAPI) ([]MultipartInfo, bool, error) {
+func (xl xlObjects) listMultipartUploadIDs(bucketName, objectName, uploadIDMarker string, count int, disk StorageAPI) ([]MultipartInfo, bool, error) {
 	var uploads []MultipartInfo
 	// Read `uploads.json`.
 	uploadsJSON, err := readUploadsJSON(bucketName, objectName, disk)

cmd/object-handlers-common.go

@@ -230,12 +230,6 @@ func isETagEqual(left, right string) bool {
 // is a common function to be called from object handlers and
 // web handlers.
 func deleteObject(obj ObjectLayer, bucket, object string, r *http.Request) (err error) {
-	// Acquire a write lock before deleting the object.
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
-	if err = objectLock.GetLock(globalOperationTimeout); err != nil {
-		return err
-	}
-	defer objectLock.Unlock()
 
 	// Proceed to delete the object.
 	if err = obj.DeleteObject(bucket, object); err != nil {

cmd/object-handlers.go

@@ -107,14 +107,6 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 		return
 	}
 
-	// Lock the object before reading.
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
-	if objectLock.GetRLock(globalObjectTimeout) != nil {
-		writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-		return
-	}
-	defer objectLock.RUnlock()
-
 	objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
 		apiErr := toAPIErrorCode(err)
@@ -182,7 +174,7 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 
 	httpWriter := ioutil.WriteOnClose(writer)
 	// Reads the object at startOffset and writes to mw.
-	if err = objectAPI.GetObject(bucket, object, startOffset, length, httpWriter); err != nil {
+	if err = objectAPI.GetObject(bucket, object, startOffset, length, httpWriter, objInfo.ETag); err != nil {
 		errorIf(err, "Unable to write to client.")
 		if !httpWriter.HasWritten() { // write error response only if no data has been written to client yet
 			writeErrorResponse(w, toAPIErrorCode(err), r.URL)
@@ -234,14 +226,6 @@ func (api objectAPIHandlers) HeadObjectHandler(w http.ResponseWriter, r *http.Re
 		return
 	}
 
-	// Lock the object before reading.
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
-	if objectLock.GetRLock(globalObjectTimeout) != nil {
-		writeErrorResponseHeadersOnly(w, ErrOperationTimedOut)
-		return
-	}
-	defer objectLock.RUnlock()
-
 	objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
 		apiErr := toAPIErrorCode(err)
@@ -362,32 +346,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 		writeErrorResponse(w, ErrNotImplemented, r.URL)
 		return
 	}
-
 	cpSrcDstSame := srcBucket == dstBucket && srcObject == dstObject
-	// Hold write lock on destination since in both cases
-	// - if source and destination are same
-	// - if source and destination are different
-	// it is the sole mutating state.
-	objectDWLock := globalNSMutex.NewNSLock(dstBucket, dstObject)
-	if objectDWLock.GetLock(globalObjectTimeout) != nil {
-		writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-		return
-	}
-	defer objectDWLock.Unlock()
-
-	// if source and destination are different, we have to hold
-	// additional read lock as well to protect against writes on
-	// source.
-	if !cpSrcDstSame {
-		// Hold read locks on source object only if we are
-		// going to read data from source object.
-		objectSRLock := globalNSMutex.NewNSLock(srcBucket, srcObject)
-		if objectSRLock.GetRLock(globalObjectTimeout) != nil {
-			writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-			return
-		}
-		defer objectSRLock.RUnlock()
-	}
 
 	objInfo, err := objectAPI.GetObjectInfo(srcBucket, srcObject)
 	if err != nil {
@@ -424,7 +383,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 
 	// Copy source object to destination, if source and destination
 	// object is same then only metadata is updated.
-	objInfo, err = objectAPI.CopyObject(srcBucket, srcObject, dstBucket, dstObject, newMetadata)
+	objInfo, err = objectAPI.CopyObject(srcBucket, srcObject, dstBucket, dstObject, newMetadata, objInfo.ETag)
 	if err != nil {
 		writeErrorResponse(w, toAPIErrorCode(err), r.URL)
 		return
@@ -538,14 +497,6 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 		}
 	}
 
-	// Lock the object.
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
-	if objectLock.GetLock(globalObjectTimeout) != nil {
-		writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-		return
-	}
-	defer objectLock.Unlock()
-
 	var (
 		md5hex    = hex.EncodeToString(md5Bytes)
 		sha256hex = ""
@@ -749,15 +700,6 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 		return
 	}
 
-	// Hold read locks on source object only if we are
-	// going to read data from source object.
-	objectSRLock := globalNSMutex.NewNSLock(srcBucket, srcObject)
-	if objectSRLock.GetRLock(globalObjectTimeout) != nil {
-		writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-		return
-	}
-	defer objectSRLock.RUnlock()
-
 	objInfo, err := objectAPI.GetObjectInfo(srcBucket, srcObject)
 	if err != nil {
 		writeErrorResponse(w, toAPIErrorCode(err), r.URL)
@@ -799,7 +741,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 	// Copy source object to destination, if source and destination
 	// object is same then only metadata is updated.
 	partInfo, err := objectAPI.CopyObjectPart(srcBucket, srcObject, dstBucket,
-		dstObject, uploadID, partID, startOffset, length, nil)
+		dstObject, uploadID, partID, startOffset, length, nil, objInfo.ETag)
 	if err != nil {
 		writeErrorResponse(w, toAPIErrorCode(err), r.URL)
 		return
@@ -1057,14 +999,6 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 		completeParts = append(completeParts, part)
 	}
 
-	// Hold write lock on the object.
-	destLock := globalNSMutex.NewNSLock(bucket, object)
-	if destLock.GetLock(globalObjectTimeout) != nil {
-		writeErrorResponse(w, ErrOperationTimedOut, r.URL)
-		return
-	}
-	defer destLock.Unlock()
-
 	objInfo, err := objectAPI.CompleteMultipartUpload(bucket, object, uploadID, completeParts)
 	if err != nil {
 		err = errors.Cause(err)

cmd/object-handlers_test.go

@@ -766,7 +766,7 @@ func testAPIPutObjectStreamSigV4Handler(obj ObjectLayer, instanceType, bucketNam
 				t.Fatalf("Test %d: %s: ContentEncoding is set to \"%s\" which is unexpected, expected \"%s\"", i+1, instanceType, objInfo.ContentEncoding, expectedContentEncoding)
 			}
 			buffer := new(bytes.Buffer)
-			err = obj.GetObject(testCase.bucketName, testCase.objectName, 0, int64(testCase.dataLen), buffer)
+			err = obj.GetObject(testCase.bucketName, testCase.objectName, 0, int64(testCase.dataLen), buffer, objInfo.ETag)
 			if err != nil {
 				t.Fatalf("Test %d: %s: Failed to fetch the copied object: <ERROR> %s", i+1, instanceType, err)
 			}
@@ -943,7 +943,7 @@ func testAPIPutObjectHandler(obj ObjectLayer, instanceType, bucketName string, a
 			buffer := new(bytes.Buffer)
 
 			// Fetch the object to check whether the content is same as the one uploaded via PutObject.
-			err = obj.GetObject(testCase.bucketName, testCase.objectName, 0, int64(len(bytesData)), buffer)
+			err = obj.GetObject(testCase.bucketName, testCase.objectName, 0, int64(len(bytesData)), buffer, "")
 			if err != nil {
 				t.Fatalf("Test %d: %s: Failed to fetch the copied object: <ERROR> %s", i+1, instanceType, err)
 			}
@@ -986,7 +986,7 @@ func testAPIPutObjectHandler(obj ObjectLayer, instanceType, bucketName string, a
 		if testCase.expectedRespStatus == http.StatusOK {
 			buffer := new(bytes.Buffer)
 			// Fetch the object to check whether the content is same as the one uploaded via PutObject.
-			err = obj.GetObject(testCase.bucketName, testCase.objectName, 0, int64(len(bytesData)), buffer)
+			err = obj.GetObject(testCase.bucketName, testCase.objectName, 0, int64(len(bytesData)), buffer, "")
 			if err != nil {
 				t.Fatalf("Test %d: %s: Failed to fetch the copied object: <ERROR> %s", i+1, instanceType, err)
 			}
@@ -1138,7 +1138,7 @@ func testAPICopyObjectPartHandlerSanity(obj ObjectLayer, instanceType, bucketNam
 	}
 
 	var buf bytes.Buffer
-	if err = obj.GetObject(bucketName, testObject, 0, int64(len(bytesData[0].byteData)), &buf); err != nil {
+	if err = obj.GetObject(bucketName, testObject, 0, int64(len(bytesData[0].byteData)), &buf, ""); err != nil {
 		t.Fatalf("Test: %s reading completed file failed: <ERROR> %v", instanceType, err)
 	}
 	if !bytes.Equal(buf.Bytes(), bytesData[0].byteData) {
@@ -1795,7 +1795,7 @@ func testAPICopyObjectHandler(obj ObjectLayer, instanceType, bucketName string,
 		if rec.Code == http.StatusOK {
 			// See if the new object is formed.
 			// testing whether the copy was successful.
-			err = obj.GetObject(testCase.bucketName, testCase.newObjectName, 0, int64(len(bytesData[0].byteData)), buffers[0])
+			err = obj.GetObject(testCase.bucketName, testCase.newObjectName, 0, int64(len(bytesData[0].byteData)), buffers[0], "")
 			if err != nil {
 				t.Fatalf("Test %d: %s: Failed to fetch the copied object: <ERROR> %s", i+1, instanceType, err)
 			}

cmd/object_api_suite_test.go

@@ -207,7 +207,7 @@ func testMultipleObjectCreation(obj ObjectLayer, instanceType string, t TestErrH
 
 	for key, value := range objects {
 		var byteBuffer bytes.Buffer
-		err = obj.GetObject("bucket", key, 0, int64(len(value)), &byteBuffer)
+		err = obj.GetObject("bucket", key, 0, int64(len(value)), &byteBuffer, "")
 		if err != nil {
 			t.Fatalf("%s: <ERROR> %s", instanceType, err)
 		}
@@ -456,7 +456,7 @@ func testObjectOverwriteWorks(obj ObjectLayer, instanceType string, t TestErrHan
 	}
 
 	var bytesBuffer bytes.Buffer
-	err = obj.GetObject("bucket", "object", 0, length, &bytesBuffer)
+	err = obj.GetObject("bucket", "object", 0, length, &bytesBuffer, "")
 	if err != nil {
 		t.Fatalf("%s: <ERROR> %s", instanceType, err)
 	}
@@ -523,7 +523,7 @@ func testPutObject(obj ObjectLayer, instanceType string, t TestErrHandler) {
 	if err != nil {
 		t.Fatalf("%s: <ERROR> %s", instanceType, err)
 	}
-	err = obj.GetObject("bucket", "object", 0, length, &bytesBuffer1)
+	err = obj.GetObject("bucket", "object", 0, length, &bytesBuffer1, "")
 	if err != nil {
 		t.Fatalf("%s: <ERROR> %s", instanceType, err)
 	}
@@ -536,7 +536,7 @@ func testPutObject(obj ObjectLayer, instanceType string, t TestErrHandler) {
 	if err != nil {
 		t.Fatalf("%s: <ERROR> %s", instanceType, err)
 	}
-	err = obj.GetObject("bucket", "object", 0, length, &bytesBuffer2)
+	err = obj.GetObject("bucket", "object", 0, length, &bytesBuffer2, "")
 	if err != nil {
 		t.Fatalf("%s: <ERROR> %s", instanceType, err)
 	}
@@ -566,7 +566,7 @@ func testPutObjectInSubdir(obj ObjectLayer, instanceType string, t TestErrHandle
 	}
 
 	var bytesBuffer bytes.Buffer
-	err = obj.GetObject("bucket", "dir1/dir2/object", 0, length, &bytesBuffer)
+	err = obj.GetObject("bucket", "dir1/dir2/object", 0, length, &bytesBuffer, "")
 	if err != nil {
 		t.Fatalf("%s: <ERROR> %s", instanceType, err)
 	}

cmd/web-handlers.go

@@ -131,12 +131,6 @@ func (web *webAPIHandlers) MakeBucket(r *http.Request, args *MakeBucketArgs, rep
 		return toJSONError(errInvalidBucketName)
 	}
 
-	bucketLock := globalNSMutex.NewNSLock(args.BucketName, "")
-	if err := bucketLock.GetLock(globalObjectTimeout); err != nil {
-		return toJSONError(errOperationTimedOut)
-	}
-	defer bucketLock.Unlock()
-
 	if err := objectAPI.MakeBucketWithLocation(args.BucketName, globalServerConfig.GetRegion()); err != nil {
 		return toJSONError(err, args.BucketName)
 	}
@@ -160,12 +154,6 @@ func (web *webAPIHandlers) DeleteBucket(r *http.Request, args *RemoveBucketArgs,
 		return toJSONError(errAuthentication)
 	}
 
-	bucketLock := globalNSMutex.NewNSLock(args.BucketName, "")
-	if err := bucketLock.GetLock(globalObjectTimeout); err != nil {
-		return toJSONError(errOperationTimedOut)
-	}
-	defer bucketLock.Unlock()
-
 	err := objectAPI.DeleteBucket(args.BucketName)
 	if err != nil {
 		return toJSONError(err, args.BucketName)
@@ -564,14 +552,6 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Lock the object.
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
-	if objectLock.GetLock(globalObjectTimeout) != nil {
-		writeWebErrorResponse(w, errOperationTimedOut)
-		return
-	}
-	defer objectLock.Unlock()
-
 	hashReader, err := hash.NewReader(r.Body, size, "", "")
 	if err != nil {
 		writeWebErrorResponse(w, err)
@@ -614,15 +594,7 @@ func (web *webAPIHandlers) Download(w http.ResponseWriter, r *http.Request) {
 	// Add content disposition.
 	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", path.Base(object)))
 
-	// Lock the object before reading.
+	if err := objectAPI.GetObject(bucket, object, 0, -1, w, ""); err != nil {
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
-	if objectLock.GetRLock(globalObjectTimeout) != nil {
-		writeWebErrorResponse(w, errOperationTimedOut)
-		return
-	}
-	defer objectLock.RUnlock()
-
-	if err := objectAPI.GetObject(bucket, object, 0, -1, w); err != nil {
 		/// No need to print error, response writer already written to.
 		return
 	}
@@ -686,7 +658,7 @@ func (web *webAPIHandlers) DownloadZip(w http.ResponseWriter, r *http.Request) {
 				writeWebErrorResponse(w, errUnexpected)
 				return err
 			}
-			return objectAPI.GetObject(args.BucketName, objectName, 0, info.Size, writer)
+			return objectAPI.GetObject(args.BucketName, objectName, 0, info.Size, writer, "")
 		}
 
 		if !hasSuffix(object, slashSeparator) {

cmd/web-handlers_test.go

@@ -887,7 +887,7 @@ func testUploadWebHandler(obj ObjectLayer, instanceType string, t TestErrHandler
 	}
 
 	var byteBuffer bytes.Buffer
-	err = obj.GetObject(bucketName, objectName, 0, int64(len(content)), &byteBuffer)
+	err = obj.GetObject(bucketName, objectName, 0, int64(len(content)), &byteBuffer, "")
 	if err != nil {
 		t.Fatalf("Failed, %v", err)
 	}

cmd/xl-v1-bucket.go

@@ -33,6 +33,11 @@ var bucketMetadataOpIgnoredErrs = append(bucketOpIgnoredErrs, errVolumeNotFound)
 
 // MakeBucket - make a bucket.
 func (xl xlObjects) MakeBucketWithLocation(bucket, location string) error {
+	bucketLock := xl.nsMutex.NewNSLock(bucket, "")
+	if err := bucketLock.GetLock(globalObjectTimeout); err != nil {
+		return err
+	}
+	defer bucketLock.Unlock()
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
 		return errors.Trace(BucketNameInvalid{Bucket: bucket})

cmd/xl-v1-healing.go

@@ -83,6 +83,11 @@ func (xl xlObjects) HealBucket(bucket string) error {
 
 	// get write quorum for an object
 	writeQuorum := len(xl.storageDisks)/2 + 1
+	bucketLock := xl.nsMutex.NewNSLock(bucket, "")
+	if err := bucketLock.GetLock(globalHealingTimeout); err != nil {
+		return err
+	}
+	defer bucketLock.Unlock()
 
 	// Heal bucket.
 	if err := healBucket(xl.storageDisks, bucket, writeQuorum); err != nil {
@@ -95,11 +100,6 @@ func (xl xlObjects) HealBucket(bucket string) error {
 
 // Heal bucket - create buckets on disks where it does not exist.
 func healBucket(storageDisks []StorageAPI, bucket string, writeQuorum int) error {
-	bucketLock := globalNSMutex.NewNSLock(bucket, "")
-	if err := bucketLock.GetLock(globalHealingTimeout); err != nil {
-		return err
-	}
-	defer bucketLock.Unlock()
 
 	// Initialize sync waitgroup.
 	var wg = &sync.WaitGroup{}
@@ -316,6 +316,12 @@ func quickHeal(xlObj xlObjects, writeQuorum int, readQuorum int) error {
 	for bucketName, occCount := range bucketOcc {
 		// Heal bucket only if healing is needed.
 		if occCount != len(xlObj.storageDisks) {
+			bucketLock := xlObj.nsMutex.NewNSLock(bucketName, "")
+			if perr := bucketLock.GetLock(globalHealingTimeout); perr != nil {
+				return perr
+			}
+			defer bucketLock.Unlock()
+
 			// Heal bucket and then proceed to heal bucket metadata if any.
 			if err = healBucket(xlObj.storageDisks, bucketName, writeQuorum); err == nil {
 				if err = healBucketMetadata(xlObj, bucketName); err == nil {
@@ -542,7 +548,7 @@ func (xl xlObjects) HealObject(bucket, object string) (int, int, error) {
 	}
 
 	// Lock the object before healing.
-	objectLock := globalNSMutex.NewNSLock(bucket, object)
+	objectLock := xl.nsMutex.NewNSLock(bucket, object)
 	if err := objectLock.GetRLock(globalHealingTimeout); err != nil {
 		return 0, 0, err
 	}

cmd/xl-v1-list-objects-heal.go

@@ -143,7 +143,7 @@ func (xl xlObjects) listObjectsHeal(bucket, prefix, marker, delimiter string, ma
 		}
 
 		// Check if the current object needs healing
-		objectLock := globalNSMutex.NewNSLock(bucket, objInfo.Name)
+		objectLock := xl.nsMutex.NewNSLock(bucket, objInfo.Name)
 		if err := objectLock.GetRLock(globalHealingTimeout); err != nil {
 			return loi, err
 		}
@@ -223,12 +223,12 @@ func (xl xlObjects) ListUploadsHeal(bucket, prefix, marker, uploadIDMarker,
 }
 
 // Fetches list of multipart uploadIDs given bucket, keyMarker, uploadIDMarker.
-func fetchMultipartUploadIDs(bucket, keyMarker, uploadIDMarker string,
+func (xl xlObjects) fetchMultipartUploadIDs(bucket, keyMarker, uploadIDMarker string,
 	maxUploads int, disks []StorageAPI) (uploads []MultipartInfo, end bool,
 	err error) {
 
 	// Hold a read lock on keyMarker path.
-	keyMarkerLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+	keyMarkerLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 		pathJoin(bucket, keyMarker))
 	if err = keyMarkerLock.GetRLock(globalHealingTimeout); err != nil {
 		return uploads, end, err
@@ -237,7 +237,7 @@ func fetchMultipartUploadIDs(bucket, keyMarker, uploadIDMarker string,
 		if disk == nil {
 			continue
 		}
-		uploads, end, err = listMultipartUploadIDs(bucket, keyMarker,
+		uploads, end, err = xl.listMultipartUploadIDs(bucket, keyMarker,
 			uploadIDMarker, maxUploads, disk)
 		if err == nil ||
 			!errors.IsErrIgnored(err, objMetadataOpIgnoredErrs...) {
@@ -268,7 +268,7 @@ func (xl xlObjects) listMultipartUploadsHeal(bucket, prefix, keyMarker,
 	// List all upload ids for the given keyMarker, starting from
 	// uploadIDMarker.
 	if uploadIDMarker != "" {
-		uploads, _, err = fetchMultipartUploadIDs(bucket, keyMarker,
+		uploads, _, err = xl.fetchMultipartUploadIDs(bucket, keyMarker,
 			uploadIDMarker, maxUploads, xl.getLoadBalancedDisks())
 		if err != nil {
 			return lmi, err
@@ -349,7 +349,7 @@ func (xl xlObjects) listMultipartUploadsHeal(bucket, prefix, keyMarker,
 			var newUploads []MultipartInfo
 			var end bool
 			uploadIDMarker = ""
-			newUploads, end, err = fetchMultipartUploadIDs(bucket, entry, uploadIDMarker,
+			newUploads, end, err = xl.fetchMultipartUploadIDs(bucket, entry, uploadIDMarker,
 				uploadsLeft, xl.getLoadBalancedDisks())
 			if err != nil {
 				return lmi, err

cmd/xl-v1-multipart.go

@@ -306,7 +306,7 @@ func (xl xlObjects) listMultipartUploadsCleanup(bucket, prefix, keyMarker, uploa
 	// uploadIDMarker first.
 	if uploadIDMarker != "" {
 		// hold lock on keyMarker path
-		keyMarkerLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+		keyMarkerLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 			pathJoin(bucket, keyMarker))
 		if err = keyMarkerLock.GetRLock(globalListingTimeout); err != nil {
 			return lmi, err
@@ -315,7 +315,7 @@ func (xl xlObjects) listMultipartUploadsCleanup(bucket, prefix, keyMarker, uploa
 			if disk == nil {
 				continue
 			}
-			uploads, _, err = listMultipartUploadIDs(bucket, keyMarker, uploadIDMarker, maxUploads, disk)
+			uploads, _, err = xl.listMultipartUploadIDs(bucket, keyMarker, uploadIDMarker, maxUploads, disk)
 			if err == nil {
 				break
 			}
@@ -374,7 +374,7 @@ func (xl xlObjects) listMultipartUploadsCleanup(bucket, prefix, keyMarker, uploa
 
 			// For the new object entry we get all its
 			// pending uploadIDs.
-			entryLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+			entryLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 				pathJoin(bucket, entry))
 			if err = entryLock.GetRLock(globalListingTimeout); err != nil {
 				return lmi, err
@@ -384,7 +384,7 @@ func (xl xlObjects) listMultipartUploadsCleanup(bucket, prefix, keyMarker, uploa
 				if disk == nil {
 					continue
 				}
-				newUploads, end, err = listMultipartUploadIDs(bucket, entry, uploadIDMarker, maxUploads, disk)
+				newUploads, end, err = xl.listMultipartUploadIDs(bucket, entry, uploadIDMarker, maxUploads, disk)
 				if err == nil {
 					break
 				}
@@ -465,8 +465,14 @@ func (xl xlObjects) ListMultipartUploads(bucket, object, keyMarker, uploadIDMark
 		if disk == nil {
 			continue
 		}
-
+		// Hold the lock so that two parallel complete-multipart-uploads
-		uploads, _, err := listMultipartUploadIDs(bucket, object, uploadIDMarker, maxUploads, disk)
+		// do not leave a stale uploads.json behind.
+		objectMPartPathLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
+		if err := objectMPartPathLock.GetRLock(globalListingTimeout); err != nil {
+			return lmi, err
+		}
+		defer objectMPartPathLock.RUnlock()
+		uploads, _, err := xl.listMultipartUploadIDs(bucket, object, uploadIDMarker, maxUploads, disk)
 		if err != nil {
 			return lmi, err
 		}
@@ -525,7 +531,7 @@ func (xl xlObjects) newMultipartUpload(bucket string, object string, meta map[st
 
 	// This lock needs to be held for any changes to the directory
 	// contents of ".minio.sys/multipart/object/"
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+	objectMPartPathLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 		pathJoin(bucket, object))
 	if err := objectMPartPathLock.GetLock(globalOperationTimeout); err != nil {
 		return "", err
@@ -582,17 +588,34 @@ func (xl xlObjects) NewMultipartUpload(bucket, object string, meta map[string]st
 // data is read from an existing object.
 //
 // Implements S3 compatible Upload Part Copy API.
-func (xl xlObjects) CopyObjectPart(srcBucket, srcObject, dstBucket, dstObject, uploadID string, partID int, startOffset int64, length int64, metadata map[string]string) (pi PartInfo, e error) {
+func (xl xlObjects) CopyObjectPart(srcBucket, srcObject, dstBucket, dstObject, uploadID string, partID int, startOffset int64, length int64, metadata map[string]string, srcEtag string) (pi PartInfo, e error) {
+	// Hold read locks on source object only if we are
+	// going to read data from source object.
+	objectSRLock := xl.nsMutex.NewNSLock(srcBucket, srcObject)
+	if err := objectSRLock.GetRLock(globalObjectTimeout); err != nil {
+		return pi, err
+	}
+	defer objectSRLock.RUnlock()
+
 	if err := checkNewMultipartArgs(srcBucket, srcObject, xl); err != nil {
 		return pi, err
 	}
 
+	if srcEtag != "" {
+		objInfo, err := xl.getObjectInfo(srcBucket, srcObject)
+		if err != nil {
+			return pi, toObjectErr(err, srcBucket, srcObject)
+		}
+		if objInfo.ETag != srcEtag {
+			return pi, toObjectErr(errors.Trace(InvalidETag{}), srcBucket, srcObject)
+		}
+	}
 	// Initialize pipe.
 	pipeReader, pipeWriter := io.Pipe()
 
 	go func() {
-		if gerr := xl.GetObject(srcBucket, srcObject, startOffset, length, pipeWriter); gerr != nil {
+		if gerr := xl.getObject(srcBucket, srcObject, startOffset, length, pipeWriter, ""); gerr != nil {
-			errorIf(gerr, "Unable to read object `%s/%s`.", srcBucket, srcObject)
+			errorIf(gerr, "Unable to read %s of the object `%s/%s`.", srcBucket, srcObject)
 			pipeWriter.CloseWithError(toObjectErr(gerr, srcBucket, srcObject))
 			return
 		}
@@ -631,12 +654,20 @@ func (xl xlObjects) PutObjectPart(bucket, object, uploadID string, partID int, d
 		return pi, toObjectErr(errors.Trace(errInvalidArgument))
 	}
 
+	// Hold the lock so that two parallel complete-multipart-uploads
+	// do not leave a stale uploads.json behind.
+	objectMPartPathLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
+	if err := objectMPartPathLock.GetLock(globalOperationTimeout); err != nil {
+		return pi, err
+	}
+	defer objectMPartPathLock.Unlock()
+
 	var partsMetadata []xlMetaV1
 	var errs []error
 	uploadIDPath := pathJoin(bucket, object, uploadID)
 
 	// pre-check upload id lock.
-	preUploadIDLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, uploadIDPath)
+	preUploadIDLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket, uploadIDPath)
 	if err := preUploadIDLock.GetRLock(globalOperationTimeout); err != nil {
 		return pi, err
 	}
@@ -708,7 +739,7 @@ func (xl xlObjects) PutObjectPart(bucket, object, uploadID string, partID int, d
 	}
 
 	// post-upload check (write) lock
-	postUploadIDLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, uploadIDPath)
+	postUploadIDLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket, uploadIDPath)
 	if err = postUploadIDLock.GetLock(globalOperationTimeout); err != nil {
 		return pi, err
 	}
@@ -859,10 +890,16 @@ func (xl xlObjects) ListObjectParts(bucket, object, uploadID string, partNumberM
 	if err := checkListPartsArgs(bucket, object, xl); err != nil {
 		return lpi, err
 	}
-
+	// Hold the lock so that two parallel complete-multipart-uploads
+	// do not leave a stale uploads.json behind.
+	objectMPartPathLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
+	if err := objectMPartPathLock.GetRLock(globalListingTimeout); err != nil {
+		return lpi, errors.Trace(err)
+	}
+	defer objectMPartPathLock.RUnlock()
 	// Hold lock so that there is no competing
 	// abort-multipart-upload or complete-multipart-upload.
-	uploadIDLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+	uploadIDLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 		pathJoin(bucket, object, uploadID))
 	if err := uploadIDLock.GetLock(globalListingTimeout); err != nil {
 		return lpi, err
@@ -886,14 +923,19 @@ func (xl xlObjects) CompleteMultipartUpload(bucket string, object string, upload
 	if err := checkCompleteMultipartArgs(bucket, object, xl); err != nil {
 		return oi, err
 	}
-
+	// Hold write lock on the object.
+	destLock := xl.nsMutex.NewNSLock(bucket, object)
+	if err := destLock.GetLock(globalObjectTimeout); err != nil {
+		return oi, err
+	}
+	defer destLock.Unlock()
 	// Hold lock so that
 	//
 	// 1) no one aborts this multipart upload
 	//
 	// 2) no one does a parallel complete-multipart-upload on this
 	// multipart upload
-	uploadIDLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+	uploadIDLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 		pathJoin(bucket, object, uploadID))
 	if err := uploadIDLock.GetLock(globalOperationTimeout); err != nil {
 		return oi, err
@@ -1034,7 +1076,7 @@ func (xl xlObjects) CompleteMultipartUpload(bucket string, object string, upload
 			// Prefetch the object from disk by triggering a fake GetObject call
 			// Unlike a regular single PutObject,  multipart PutObject is comes in
 			// stages and it is harder to cache.
-			go xl.GetObject(bucket, object, 0, objectSize, ioutil.Discard)
+			go xl.GetObject(bucket, object, 0, objectSize, ioutil.Discard, s3MD5)
 		}
 	}()
 
@@ -1075,7 +1117,7 @@ func (xl xlObjects) CompleteMultipartUpload(bucket string, object string, upload
 	// Hold the lock so that two parallel
 	// complete-multipart-uploads do not leave a stale
 	// uploads.json behind.
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+	objectMPartPathLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 		pathJoin(bucket, object))
 	if err = objectMPartPathLock.GetLock(globalOperationTimeout); err != nil {
 		return oi, toObjectErr(err, bucket, object)
@@ -1155,7 +1197,7 @@ func (xl xlObjects) abortMultipartUpload(bucket, object, uploadID string) (err e
 
 	// hold lock so we don't compete with a complete, or abort
 	// multipart request.
-	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+	objectMPartPathLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 		pathJoin(bucket, object))
 	if err = objectMPartPathLock.GetLock(globalOperationTimeout); err != nil {
 		return toObjectErr(err, bucket, object)
@@ -1186,10 +1228,9 @@ func (xl xlObjects) AbortMultipartUpload(bucket, object, uploadID string) error
 	if err := checkAbortMultipartArgs(bucket, object, xl); err != nil {
 		return err
 	}
-
 	// Hold lock so that there is no competing
 	// complete-multipart-upload or put-object-part.
-	uploadIDLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket,
+	uploadIDLock := xl.nsMutex.NewNSLock(minioMetaMultipartBucket,
 		pathJoin(bucket, object, uploadID))
 	if err := uploadIDLock.GetLock(globalOperationTimeout); err != nil {
 		return err

cmd/xl-v1-object.go

@@ -57,7 +57,40 @@ func (xl xlObjects) prepareFile(bucket, object string, size int64, onlineDisks [
 // CopyObject - copy object source object to destination object.
 // if source object and destination object are same we only
 // update metadata.
-func (xl xlObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string, metadata map[string]string) (oi ObjectInfo, e error) {
+func (xl xlObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string, metadata map[string]string, srcEtag string) (oi ObjectInfo, e error) {
+	cpSrcDstSame := srcBucket == dstBucket && srcObject == dstObject
+	// Hold write lock on destination since in both cases
+	// - if source and destination are same
+	// - if source and destination are different
+	// it is the sole mutating state.
+	objectDWLock := xl.nsMutex.NewNSLock(dstBucket, dstObject)
+	if err := objectDWLock.GetLock(globalObjectTimeout); err != nil {
+		return oi, err
+	}
+	defer objectDWLock.Unlock()
+	// if source and destination are different, we have to hold
+	// additional read lock as well to protect against writes on
+	// source.
+	if !cpSrcDstSame {
+		// Hold read locks on source object only if we are
+		// going to read data from source object.
+		objectSRLock := xl.nsMutex.NewNSLock(srcBucket, srcObject)
+		if err := objectSRLock.GetRLock(globalObjectTimeout); err != nil {
+			return oi, err
+		}
+		defer objectSRLock.RUnlock()
+	}
+
+	if srcEtag != "" {
+		objInfo, perr := xl.getObjectInfo(srcBucket, srcObject)
+		if perr != nil {
+			return oi, toObjectErr(perr, srcBucket, srcObject)
+		}
+		if objInfo.ETag != srcEtag {
+			return oi, toObjectErr(errors.Trace(InvalidETag{}), srcBucket, srcObject)
+		}
+	}
+
 	// Read metadata associated with the object from all disks.
 	metaArr, errs := readAllXLMetadata(xl.storageDisks, srcBucket, srcObject)
 
@@ -114,8 +147,8 @@ func (xl xlObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string
 
 	go func() {
 		var startOffset int64 // Read the whole file.
-		if gerr := xl.GetObject(srcBucket, srcObject, startOffset, length, pipeWriter); gerr != nil {
+		if gerr := xl.getObject(srcBucket, srcObject, startOffset, length, pipeWriter, ""); gerr != nil {
-			errorIf(gerr, "Unable to read object `%s/%s`.", srcBucket, srcObject)
+			errorIf(gerr, "Unable to read %s of the object `%s/%s`.", srcBucket, srcObject)
 			pipeWriter.CloseWithError(toObjectErr(gerr, srcBucket, srcObject))
 			return
 		}
@@ -127,7 +160,7 @@ func (xl xlObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string
 		return oi, toObjectErr(errors.Trace(err), dstBucket, dstObject)
 	}
 
-	objInfo, err := xl.PutObject(dstBucket, dstObject, hashReader, metadata)
+	objInfo, err := xl.putObject(dstBucket, dstObject, hashReader, metadata)
 	if err != nil {
 		return oi, toObjectErr(err, dstBucket, dstObject)
 	}
@@ -144,7 +177,19 @@ func (xl xlObjects) CopyObject(srcBucket, srcObject, dstBucket, dstObject string
 //
 // startOffset indicates the starting read location of the object.
 // length indicates the total length of the object.
-func (xl xlObjects) GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer) error {
+func (xl xlObjects) GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
+	// Lock the object before reading.
+	objectLock := xl.nsMutex.NewNSLock(bucket, object)
+	if err := objectLock.GetRLock(globalObjectTimeout); err != nil {
+		return err
+	}
+	defer objectLock.RUnlock()
+	return xl.getObject(bucket, object, startOffset, length, writer, etag)
+}
+
+// getObject wrapper for xl GetObject
+func (xl xlObjects) getObject(bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
+
 	if err := checkGetObjArgs(bucket, object); err != nil {
 		return err
 	}
@@ -311,6 +356,13 @@ func (xl xlObjects) GetObject(bucket, object string, startOffset int64, length i
 
 // GetObjectInfo - reads object metadata and replies back ObjectInfo.
 func (xl xlObjects) GetObjectInfo(bucket, object string) (oi ObjectInfo, e error) {
+	// Lock the object before reading.
+	objectLock := xl.nsMutex.NewNSLock(bucket, object)
+	if err := objectLock.GetRLock(globalObjectTimeout); err != nil {
+		return oi, err
+	}
+	defer objectLock.RUnlock()
+
 	if err := checkGetObjArgs(bucket, object); err != nil {
 		return oi, err
 	}
@@ -445,6 +497,17 @@ func renameObject(disks []StorageAPI, srcBucket, srcObject, dstBucket, dstObject
 // writes `xl.json` which carries the necessary metadata for future
 // object operations.
 func (xl xlObjects) PutObject(bucket string, object string, data *hash.Reader, metadata map[string]string) (objInfo ObjectInfo, err error) {
+	// Lock the object.
+	objectLock := xl.nsMutex.NewNSLock(bucket, object)
+	if err := objectLock.GetLock(globalObjectTimeout); err != nil {
+		return objInfo, err
+	}
+	defer objectLock.Unlock()
+	return xl.putObject(bucket, object, data, metadata)
+}
+
+// putObject wrapper for xl PutObject
+func (xl xlObjects) putObject(bucket string, object string, data *hash.Reader, metadata map[string]string) (objInfo ObjectInfo, err error) {
 	// This is a special case with size as '0' and object ends with
 	// a slash separator, we treat it like a valid operation and
 	// return success.
@@ -715,6 +778,13 @@ func (xl xlObjects) deleteObject(bucket, object string) error {
 // any error as it is not necessary for the handler to reply back a
 // response to the client request.
 func (xl xlObjects) DeleteObject(bucket, object string) (err error) {
+	// Acquire a write lock before deleting the object.
+	objectLock := xl.nsMutex.NewNSLock(bucket, object)
+	if perr := objectLock.GetLock(globalOperationTimeout); perr != nil {
+		return perr
+	}
+	defer objectLock.Unlock()
+
 	if err = checkDelObjArgs(bucket, object); err != nil {
 		return err
 	}

cmd/xl-v1-object_test.go

@@ -206,7 +206,7 @@ func TestGetObjectNoQuorum(t *testing.T) {
 			}
 		}
 		// Fetch object from store.
-		err = xl.GetObject(bucket, object, 0, int64(len("abcd")), ioutil.Discard)
+		err = xl.GetObject(bucket, object, 0, int64(len("abcd")), ioutil.Discard, "")
 		err = errors.Cause(err)
 		if err != toObjectErr(errXLReadQuorum, bucket, object) {
 			t.Errorf("Expected putObject to fail with %v, but failed with %v", toObjectErr(errXLWriteQuorum, bucket, object), err)

cmd/xl-v1.go

@@ -21,6 +21,7 @@ import (
 	"runtime/debug"
 	"sort"
 	"sync"
+	"time"
 
 	humanize "github.com/dustin/go-humanize"
 	"github.com/minio/minio/pkg/disk"
@@ -59,6 +60,9 @@ type xlObjects struct {
 
 	// Object cache enabled.
 	objCacheEnabled bool
+
+	// name space mutex for object layer
+	nsMutex *nsLockMap
 }
 
 // list of all errors that can be ignored in tree walk operation in XL
@@ -106,8 +110,8 @@ func newXLObjects(storageDisks []StorageAPI) (ObjectLayer, error) {
 		mutex:        &sync.Mutex{},
 		storageDisks: newStorageDisks,
 		listPool:     listPool,
+		nsMutex:      newNSLock(globalIsDistXL),
 	}
-
 	// Get cache size if _MINIO_CACHE environment variable is set.
 	var maxCacheSize uint64
 	if !globalXLObjCacheDisabled {
@@ -171,6 +175,63 @@ func (xl xlObjects) Shutdown() error {
 	return nil
 }
 
+// Locking operations
+
+// List namespace locks held in object layer
+func (xl xlObjects) ListLocks(bucket, prefix string, duration time.Duration) ([]VolumeLockInfo, error) {
+	xl.nsMutex.lockMapMutex.Lock()
+	defer xl.nsMutex.lockMapMutex.Unlock()
+	// Fetch current time once instead of fetching system time for every lock.
+	timeNow := UTCNow()
+	volumeLocks := []VolumeLockInfo{}
+
+	for param, debugLock := range xl.nsMutex.debugLockMap {
+		if param.volume != bucket {
+			continue
+		}
+		// N B empty prefix matches all param.path.
+		if !hasPrefix(param.path, prefix) {
+			continue
+		}
+
+		volLockInfo := VolumeLockInfo{
+			Bucket:                param.volume,
+			Object:                param.path,
+			LocksOnObject:         debugLock.counters.total,
+			TotalBlockedLocks:     debugLock.counters.blocked,
+			LocksAcquiredOnObject: debugLock.counters.granted,
+		}
+		// Filter locks that are held on bucket, prefix.
+		for opsID, lockInfo := range debugLock.lockInfo {
+			// filter locks that were held for longer than duration.
+			elapsed := timeNow.Sub(lockInfo.since)
+			if elapsed < duration {
+				continue
+			}
+			// Add locks that are held for longer than duration.
+			volLockInfo.LockDetailsOnObject = append(volLockInfo.LockDetailsOnObject,
+				OpsLockState{
+					OperationID: opsID,
+					LockSource:  lockInfo.lockSource,
+					LockType:    lockInfo.lType,
+					Status:      lockInfo.status,
+					Since:       lockInfo.since,
+				})
+			volumeLocks = append(volumeLocks, volLockInfo)
+		}
+	}
+	return volumeLocks, nil
+}
+
+// Clear namespace locks held in object layer
+func (xl xlObjects) ClearLocks(volLocks []VolumeLockInfo) error {
+	// Remove lock matching bucket/prefix held longer than duration.
+	for _, volLock := range volLocks {
+		xl.nsMutex.ForceUnlock(volLock.Bucket, volLock.Object)
+	}
+	return nil
+}
+
 // byDiskTotal is a collection satisfying sort.Interface.
 type byDiskTotal []disk.Info