distribute: Make server work with multiple remote disks

This change initializes rpc servers associated with disks that are
local. It makes object layer initialization on demand, namely on the
first request to the object layer.

Also adds lock RPC service vendorized minio/dsync

cmd/api-router.go

@@ -20,7 +20,7 @@ import router "github.com/gorilla/mux"
 
 // objectAPIHandler implements and provides http handlers for S3 API.
 type objectAPIHandlers struct {
-	ObjectAPI ObjectLayer
+	ObjectAPI func() ObjectLayer
 }
 
 // registerAPIRouter - registers S3 compatible APIs.

cmd/bucket-handlers-listobjects.go

@@ -97,10 +97,15 @@ func (api objectAPIHandlers) ListObjectsV2Handler(w http.ResponseWriter, r *http
 		writeErrorResponse(w, r, s3Error, r.URL.Path)
 		return
 	}
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	// Inititate a list objects operation based on the input params.
 	// On success would return back ListObjectsInfo object to be
 	// marshalled into S3 compatible XML header.
-	listObjectsInfo, err := api.ObjectAPI.ListObjects(bucket, prefix, marker, delimiter, maxKeys)
+	listObjectsInfo, err := objectAPI.ListObjects(bucket, prefix, marker, delimiter, maxKeys)
 	if err != nil {
 		errorIf(err, "Unable to list objects.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -151,10 +156,15 @@ func (api objectAPIHandlers) ListObjectsV1Handler(w http.ResponseWriter, r *http
 		return
 	}
 
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	// Inititate a list objects operation based on the input params.
 	// On success would return back ListObjectsInfo object to be
 	// marshalled into S3 compatible XML header.
-	listObjectsInfo, err := api.ObjectAPI.ListObjects(bucket, prefix, marker, delimiter, maxKeys)
+	listObjectsInfo, err := objectAPI.ListObjects(bucket, prefix, marker, delimiter, maxKeys)
 	if err != nil {
 		errorIf(err, "Unable to list objects.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)

cmd/bucket-handlers.go

@@ -82,7 +82,12 @@ func (api objectAPIHandlers) GetBucketLocationHandler(w http.ResponseWriter, r *
 		}
 	}
 
-	if _, err := api.ObjectAPI.GetBucketInfo(bucket); err != nil {
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	if _, err := objectAPI.GetBucketInfo(bucket); err != nil {
 		errorIf(err, "Unable to fetch bucket info.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
 		return
@@ -144,7 +149,12 @@ func (api objectAPIHandlers) ListMultipartUploadsHandler(w http.ResponseWriter,
 		}
 	}
 
-	listMultipartsInfo, err := api.ObjectAPI.ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads)
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	listMultipartsInfo, err := objectAPI.ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads)
 	if err != nil {
 		errorIf(err, "Unable to list multipart uploads.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -170,7 +180,12 @@ func (api objectAPIHandlers) ListBucketsHandler(w http.ResponseWriter, r *http.R
 		return
 	}
 
-	bucketsInfo, err := api.ObjectAPI.ListBuckets()
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	bucketsInfo, err := objectAPI.ListBuckets()
 	if err != nil {
 		errorIf(err, "Unable to list buckets.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -241,6 +256,12 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 		return
 	}
 
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+
 	var wg = &sync.WaitGroup{} // Allocate a new wait group.
 	var dErrs = make([]error, len(deleteObjects.Objects))
 
@@ -327,8 +348,13 @@ func (api objectAPIHandlers) PutBucketHandler(w http.ResponseWriter, r *http.Req
 		return
 	}
 
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	// Proceed to creating a bucket.
-	err := api.ObjectAPI.MakeBucket(bucket)
+	err := objectAPI.MakeBucket(bucket)
 	if err != nil {
 		errorIf(err, "Unable to create a bucket.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -384,7 +410,12 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 	metadata := make(map[string]string)
 	// Nothing to store right now.
 
-	md5Sum, err := api.ObjectAPI.PutObject(bucket, object, -1, fileBody, metadata)
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	md5Sum, err := objectAPI.PutObject(bucket, object, -1, fileBody, metadata)
 	if err != nil {
 		errorIf(err, "Unable to create object.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -405,7 +436,7 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 
 	if globalEventNotifier.IsBucketNotificationSet(bucket) {
 		// Fetch object info for notifications.
-		objInfo, err := api.ObjectAPI.GetObjectInfo(bucket, object)
+		objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 		if err != nil {
 			errorIf(err, "Unable to fetch object info for \"%s\"", path.Join(bucket, object))
 			return
@@ -451,7 +482,12 @@ func (api objectAPIHandlers) HeadBucketHandler(w http.ResponseWriter, r *http.Re
 		}
 	}
 
-	if _, err := api.ObjectAPI.GetBucketInfo(bucket); err != nil {
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	if _, err := objectAPI.GetBucketInfo(bucket); err != nil {
 		errorIf(err, "Unable to fetch bucket info.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
 		return
@@ -470,8 +506,13 @@ func (api objectAPIHandlers) DeleteBucketHandler(w http.ResponseWriter, r *http.
 	vars := mux.Vars(r)
 	bucket := vars["bucket"]
 
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	// Attempt to delete bucket.
-	if err := api.ObjectAPI.DeleteBucket(bucket); err != nil {
+	if err := objectAPI.DeleteBucket(bucket); err != nil {
 		errorIf(err, "Unable to delete a bucket.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
 		return

cmd/bucket-notification-handlers.go

@@ -47,7 +47,12 @@ func (api objectAPIHandlers) GetBucketNotificationHandler(w http.ResponseWriter,
 	vars := mux.Vars(r)
 	bucket := vars["bucket"]
 	// Attempt to successfully load notification config.
-	nConfig, err := loadNotificationConfig(bucket, api.ObjectAPI)
+	objAPI := api.ObjectAPI()
+	if objAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	nConfig, err := loadNotificationConfig(bucket, objAPI)
 	if err != nil && err != errNoSuchNotifications {
 		errorIf(err, "Unable to read notification configuration.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -86,7 +91,12 @@ func (api objectAPIHandlers) PutBucketNotificationHandler(w http.ResponseWriter,
 	vars := mux.Vars(r)
 	bucket := vars["bucket"]
 
-	_, err := api.ObjectAPI.GetBucketInfo(bucket)
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	_, err := objectAPI.GetBucketInfo(bucket)
 	if err != nil {
 		errorIf(err, "Unable to find bucket info.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -133,7 +143,7 @@ func (api objectAPIHandlers) PutBucketNotificationHandler(w http.ResponseWriter,
 
 	// Proceed to save notification configuration.
 	notificationConfigPath := path.Join(bucketConfigPrefix, bucket, bucketNotificationConfig)
-	_, err = api.ObjectAPI.PutObject(minioMetaBucket, notificationConfigPath, bufferSize, bytes.NewReader(buffer.Bytes()), nil)
+	_, err = objectAPI.PutObject(minioMetaBucket, notificationConfigPath, bufferSize, bytes.NewReader(buffer.Bytes()), nil)
 	if err != nil {
 		errorIf(err, "Unable to write bucket notification configuration.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -220,7 +230,13 @@ func (api objectAPIHandlers) ListenBucketNotificationHandler(w http.ResponseWrit
 	}
 
 	// Validate if bucket exists.
-	_, err := api.ObjectAPI.GetBucketInfo(bucket)
+	objAPI := api.ObjectAPI()
+	if objAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+
+	_, err := objAPI.GetBucketInfo(bucket)
 	if err != nil {
 		errorIf(err, "Unable to bucket info.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)

cmd/bucket-policy-handlers_test.go

@@ -294,13 +294,13 @@ func testPutBucketPolicyHandler(obj ObjectLayer, instanceType string, t TestErrH
 		req, err := newTestSignedRequest("PUT", getPutPolicyURL("", testCase.bucketName),
 			int64(len(bucketPolicyStr)), bytes.NewReader([]byte(bucketPolicyStr)), testCase.accessKey, testCase.secretKey)
 		if err != nil {
-			t.Fatalf("Test %d: Failed to create HTTP request for PutBucketPolicyHandler: <ERROR> %v", i+1, err)
+			t.Fatalf("Test %d: %s: Failed to create HTTP request for PutBucketPolicyHandler: <ERROR> %v", i+1, instanceType, err)
 		}
 		// Since `apiRouter` satisfies `http.Handler` it has a ServeHTTP to execute the logic ofthe handler.
 		// Call the ServeHTTP to execute the handler.
 		apiRouter.ServeHTTP(rec, req)
 		if rec.Code != testCase.expectedRespStatus {
-			t.Errorf("Test %d: Expected the response status to be `%d`, but instead found `%d`", i+1, testCase.expectedRespStatus, rec.Code)
+			t.Errorf("Test %d: %s: Expected the response status to be `%d`, but instead found `%d`", i+1, instanceType, testCase.expectedRespStatus, rec.Code)
 		}
 	}
 }

cmd/bucket-policy.go

@@ -169,7 +169,6 @@ func removeBucketPolicy(bucket string, objAPI ObjectLayer) error {
 	if !IsValidBucketName(bucket) {
 		return BucketNameInvalid{Bucket: bucket}
 	}
-
 	policyPath := pathJoin(bucketConfigPrefix, bucket, policyJSON)
 	if err := objAPI.DeleteObject(minioMetaBucket, policyPath); err != nil {
 		if _, ok := err.(ObjectNotFound); ok {

cmd/object-common.go

@@ -17,7 +17,7 @@
 package cmd
 
 import (
-	"path/filepath"
+	"net"
 	"strings"
 	"sync"
 )
@@ -53,13 +53,57 @@ func fsHouseKeeping(storageDisk StorageAPI) error {
 	return nil
 }
 
+// Check if a network path is local to this node.
+func isLocalStorage(networkPath string) bool {
+	if idx := strings.LastIndex(networkPath, ":"); idx != -1 {
+		// e.g 10.0.0.1:9000:/mnt/networkPath
+		netAddr, _ := splitNetPath(networkPath)
+		var netHost string
+		var err error
+		netHost, _, err = net.SplitHostPort(netAddr)
+		if err != nil {
+			netHost = netAddr
+		}
+		// Resolve host to address to check if the IP is loopback.
+		// If address resolution fails, assume it's a non-local host.
+		addrs, err := net.LookupHost(netHost)
+		if err != nil {
+			return false
+		}
+		for _, addr := range addrs {
+			if ip := net.ParseIP(addr); ip.IsLoopback() {
+				return true
+			}
+		}
+		iaddrs, err := net.InterfaceAddrs()
+		if err != nil {
+			return false
+		}
+		for _, addr := range addrs {
+			for _, iaddr := range iaddrs {
+				ip, _, err := net.ParseCIDR(iaddr.String())
+				if err != nil {
+					return false
+				}
+				if ip.String() == addr {
+					return true
+				}
+
+			}
+		}
+		return false
+	}
+	return true
+}
+
 // Depending on the disk type network or local, initialize storage API.
 func newStorageAPI(disk string) (storage StorageAPI, err error) {
-	if !strings.ContainsRune(disk, ':') || filepath.VolumeName(disk) != "" {
+	if isLocalStorage(disk) {
-		// Initialize filesystem storage API.
+		if idx := strings.LastIndex(disk, ":"); idx != -1 {
+			return newPosix(disk[idx+1:])
+		}
 		return newPosix(disk)
 	}
-	// Initialize rpc client storage API.
 	return newRPCClient(disk)
 }
 

cmd/object-handlers.go

@@ -102,7 +102,12 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 		}
 	}
 	// Fetch object stat info.
-	objInfo, err := api.ObjectAPI.GetObjectInfo(bucket, object)
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
 		errorIf(err, "Unable to fetch object info.")
 		apiErr := toAPIErrorCode(err)
@@ -161,7 +166,7 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 	})
 
 	// Reads the object at startOffset and writes to mw.
-	if err := api.ObjectAPI.GetObject(bucket, object, startOffset, length, writer); err != nil {
+	if err := objectAPI.GetObject(bucket, object, startOffset, length, writer); err != nil {
 		errorIf(err, "Unable to write to client.")
 		if !dataWritten {
 			// Error response only if no data has been written to client yet. i.e if
@@ -208,7 +213,12 @@ func (api objectAPIHandlers) HeadObjectHandler(w http.ResponseWriter, r *http.Re
 		}
 	}
 
-	objInfo, err := api.ObjectAPI.GetObjectInfo(bucket, object)
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
 		errorIf(err, "Unable to fetch object info.")
 		apiErr := toAPIErrorCode(err)
@@ -289,7 +299,12 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 		return
 	}
 
-	objInfo, err := api.ObjectAPI.GetObjectInfo(sourceBucket, sourceObject)
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	objInfo, err := objectAPI.GetObjectInfo(sourceBucket, sourceObject)
 	if err != nil {
 		errorIf(err, "Unable to fetch object info.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), objectSource)
@@ -311,7 +326,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 	go func() {
 		startOffset := int64(0) // Read the whole file.
 		// Get the object.
-		gErr := api.ObjectAPI.GetObject(sourceBucket, sourceObject, startOffset, objInfo.Size, pipeWriter)
+		gErr := objectAPI.GetObject(sourceBucket, sourceObject, startOffset, objInfo.Size, pipeWriter)
 		if gErr != nil {
 			errorIf(gErr, "Unable to read an object.")
 			pipeWriter.CloseWithError(gErr)
@@ -332,7 +347,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 	// same md5sum as the source.
 
 	// Create the object.
-	md5Sum, err := api.ObjectAPI.PutObject(bucket, object, size, pipeReader, metadata)
+	md5Sum, err := objectAPI.PutObject(bucket, object, size, pipeReader, metadata)
 	if err != nil {
 		// Close the this end of the pipe upon error in PutObject.
 		pipeReader.CloseWithError(err)
@@ -343,7 +358,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 	// Explicitly close the reader, before fetching object info.
 	pipeReader.Close()
 
-	objInfo, err = api.ObjectAPI.GetObjectInfo(bucket, object)
+	objInfo, err = objectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
 		errorIf(err, "Unable to fetch object info.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -418,6 +433,11 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 	// Make sure we hex encode md5sum here.
 	metadata["md5Sum"] = hex.EncodeToString(md5Bytes)
 
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	var md5Sum string
 	switch rAuthType {
 	default:
@@ -431,7 +451,7 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 			return
 		}
 		// Create anonymous object.
-		md5Sum, err = api.ObjectAPI.PutObject(bucket, object, size, r.Body, metadata)
+		md5Sum, err = objectAPI.PutObject(bucket, object, size, r.Body, metadata)
 	case authTypeStreamingSigned:
 		// Initialize stream signature verifier.
 		reader, s3Error := newSignV4ChunkedReader(r)
@@ -439,12 +459,12 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 			writeErrorResponse(w, r, s3Error, r.URL.Path)
 			return
 		}
-		md5Sum, err = api.ObjectAPI.PutObject(bucket, object, size, reader, metadata)
+		md5Sum, err = objectAPI.PutObject(bucket, object, size, reader, metadata)
 	case authTypePresigned, authTypeSigned:
 		// Initialize signature verifier.
 		reader := newSignVerify(r)
 		// Create object.
-		md5Sum, err = api.ObjectAPI.PutObject(bucket, object, size, reader, metadata)
+		md5Sum, err = objectAPI.PutObject(bucket, object, size, reader, metadata)
 	}
 	if err != nil {
 		errorIf(err, "Unable to create an object.")
@@ -458,7 +478,7 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 
 	if globalEventNotifier.IsBucketNotificationSet(bucket) {
 		// Fetch object info for notifications.
-		objInfo, err := api.ObjectAPI.GetObjectInfo(bucket, object)
+		objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 		if err != nil {
 			errorIf(err, "Unable to fetch object info for \"%s\"", path.Join(bucket, object))
 			return
@@ -506,7 +526,12 @@ func (api objectAPIHandlers) NewMultipartUploadHandler(w http.ResponseWriter, r
 	// Extract metadata that needs to be saved.
 	metadata := extractMetadataFromHeader(r.Header)
 
-	uploadID, err := api.ObjectAPI.NewMultipartUpload(bucket, object, metadata)
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	uploadID, err := objectAPI.NewMultipartUpload(bucket, object, metadata)
 	if err != nil {
 		errorIf(err, "Unable to initiate new multipart upload id.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -574,6 +599,11 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 		return
 	}
 
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	var partMD5 string
 	incomingMD5 := hex.EncodeToString(md5Bytes)
 	switch rAuthType {
@@ -588,7 +618,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 			return
 		}
 		// No need to verify signature, anonymous request access is already allowed.
-		partMD5, err = api.ObjectAPI.PutObjectPart(bucket, object, uploadID, partID, size, r.Body, incomingMD5)
+		partMD5, err = objectAPI.PutObjectPart(bucket, object, uploadID, partID, size, r.Body, incomingMD5)
 	case authTypeStreamingSigned:
 		// Initialize stream signature verifier.
 		reader, s3Error := newSignV4ChunkedReader(r)
@@ -596,11 +626,11 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 			writeErrorResponse(w, r, s3Error, r.URL.Path)
 			return
 		}
-		partMD5, err = api.ObjectAPI.PutObjectPart(bucket, object, uploadID, partID, size, reader, incomingMD5)
+		partMD5, err = objectAPI.PutObjectPart(bucket, object, uploadID, partID, size, reader, incomingMD5)
 	case authTypePresigned, authTypeSigned:
 		// Initialize signature verifier.
 		reader := newSignVerify(r)
-		partMD5, err = api.ObjectAPI.PutObjectPart(bucket, object, uploadID, partID, size, reader, incomingMD5)
+		partMD5, err = objectAPI.PutObjectPart(bucket, object, uploadID, partID, size, reader, incomingMD5)
 	}
 	if err != nil {
 		errorIf(err, "Unable to create object part.")
@@ -638,8 +668,13 @@ func (api objectAPIHandlers) AbortMultipartUploadHandler(w http.ResponseWriter,
 		}
 	}
 
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	uploadID, _, _, _ := getObjectResources(r.URL.Query())
-	if err := api.ObjectAPI.AbortMultipartUpload(bucket, object, uploadID); err != nil {
+	if err := objectAPI.AbortMultipartUpload(bucket, object, uploadID); err != nil {
 		errorIf(err, "Unable to abort multipart upload.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
 		return
@@ -680,7 +715,12 @@ func (api objectAPIHandlers) ListObjectPartsHandler(w http.ResponseWriter, r *ht
 		writeErrorResponse(w, r, ErrInvalidMaxParts, r.URL.Path)
 		return
 	}
-	listPartsInfo, err := api.ObjectAPI.ListObjectParts(bucket, object, uploadID, partNumberMarker, maxParts)
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
+	listPartsInfo, err := objectAPI.ListObjectParts(bucket, object, uploadID, partNumberMarker, maxParts)
 	if err != nil {
 		errorIf(err, "Unable to list uploaded parts.")
 		writeErrorResponse(w, r, toAPIErrorCode(err), r.URL.Path)
@@ -761,10 +801,15 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 		return
 	}
 
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	doneCh := make(chan struct{})
 	// Signal that completeMultipartUpload is over via doneCh
 	go func(doneCh chan<- struct{}) {
-		md5Sum, err = api.ObjectAPI.CompleteMultipartUpload(bucket, object, uploadID, completeParts)
+		md5Sum, err = objectAPI.CompleteMultipartUpload(bucket, object, uploadID, completeParts)
 		doneCh <- struct{}{}
 	}(doneCh)
 
@@ -799,7 +844,7 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 
 	if globalEventNotifier.IsBucketNotificationSet(bucket) {
 		// Fetch object info for notifications.
-		objInfo, err := api.ObjectAPI.GetObjectInfo(bucket, object)
+		objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 		if err != nil {
 			errorIf(err, "Unable to fetch object info for \"%s\"", path.Join(bucket, object))
 			return
@@ -842,10 +887,15 @@ func (api objectAPIHandlers) DeleteObjectHandler(w http.ResponseWriter, r *http.
 			return
 		}
 	}
+	objectAPI := api.ObjectAPI()
+	if objectAPI == nil {
+		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
+		return
+	}
 	/// http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectDELETE.html
 	/// Ignore delete object errors, since we are suppposed to reply
 	/// only 204.
-	if err := api.ObjectAPI.DeleteObject(bucket, object); err != nil {
+	if err := objectAPI.DeleteObject(bucket, object); err != nil {
 		writeSuccessNoContent(w)
 		return
 	}

cmd/routers.go

@@ -32,6 +32,7 @@ func newObjectLayer(disks, ignoredDisks []string) (ObjectLayer, error) {
 		// Initialize FS object layer.
 		return newFSObjects(exportPath)
 	}
+	// TODO: use dsync to block other concurrently booting up nodes.
 	// Initialize XL object layer.
 	objAPI, err := newXLObjects(disks, ignoredDisks)
 	if err == errXLWriteQuorum {
@@ -40,65 +41,75 @@ func newObjectLayer(disks, ignoredDisks []string) (ObjectLayer, error) {
 	return objAPI, err
 }
 
+func newObjectLayerFactory(disks, ignoredDisks []string) func() ObjectLayer {
+	var objAPI ObjectLayer
+	// FIXME: This needs to be go-routine safe.
+	return func() ObjectLayer {
+		var err error
+		if objAPI != nil {
+			return objAPI
+		}
+		objAPI, err = newObjectLayer(disks, ignoredDisks)
+		if err != nil {
+			return nil
+		}
+		// Migrate bucket policy from configDir to .minio.sys/buckets/
+		err = migrateBucketPolicyConfig(objAPI)
+		fatalIf(err, "Unable to migrate bucket policy from config directory")
+
+		err = cleanupOldBucketPolicyConfigs()
+		fatalIf(err, "Unable to clean up bucket policy from config directory.")
+
+		// Initialize and monitor shutdown signals.
+		err = initGracefulShutdown(os.Exit)
+		fatalIf(err, "Unable to initialize graceful shutdown operation")
+
+		// Register the callback that should be called when the process shuts down.
+		globalShutdownCBs.AddObjectLayerCB(func() errCode {
+			if sErr := objAPI.Shutdown(); sErr != nil {
+				return exitFailure
+			}
+			return exitSuccess
+		})
+
+		// Initialize a new event notifier.
+		err = initEventNotifier(objAPI)
+		fatalIf(err, "Unable to initialize event notification queue")
+
+		// Initialize and load bucket policies.
+		err = initBucketPolicies(objAPI)
+		fatalIf(err, "Unable to load all bucket policies")
+
+		return objAPI
+	}
+}
+
 // configureServer handler returns final handler for the http server.
 func configureServerHandler(srvCmdConfig serverCmdConfig) http.Handler {
-	// Initialize name space lock.
+	// Initialize Namespace locking.
 	initNSLock()
 
-	objAPI, err := newObjectLayer(srvCmdConfig.disks, srvCmdConfig.ignoredDisks)
+	// Initialize storage rpc servers for every disk that is hosted on this node.
-	fatalIf(err, "Unable to intialize object layer.")
+	storageRPCs, err := newRPCServer(srvCmdConfig)
-
-	// Migrate bucket policy from configDir to .minio.sys/buckets/
-	err = migrateBucketPolicyConfig(objAPI)
-	fatalIf(err, "Unable to migrate bucket policy from config directory")
-
-	err = cleanupOldBucketPolicyConfigs()
-	fatalIf(err, "Unable to clean up bucket policy from config directory.")
-
-	// Initialize storage rpc server.
-	storageRPC, err := newRPCServer(srvCmdConfig.disks[0]) // FIXME: should only have one path.
 	fatalIf(err, "Unable to initialize storage RPC server.")
 
+	newObjectLayerFn := newObjectLayerFactory(srvCmdConfig.disks, srvCmdConfig.ignoredDisks)
 	// Initialize API.
 	apiHandlers := objectAPIHandlers{
-		ObjectAPI: objAPI,
+		ObjectAPI: newObjectLayerFn,
 	}
 
 	// Initialize Web.
 	webHandlers := &webAPIHandlers{
-		ObjectAPI: objAPI,
+		ObjectAPI: newObjectLayerFn,
 	}
 
-	// Initialize Controller.
-	ctrlHandlers := &controllerAPIHandlers{
-		ObjectAPI: objAPI,
-	}
-
-	// Initialize and monitor shutdown signals.
-	err = initGracefulShutdown(os.Exit)
-	fatalIf(err, "Unable to initialize graceful shutdown operation")
-
-	// Register the callback that should be called when the process shuts down.
-	globalShutdownCBs.AddObjectLayerCB(func() errCode {
-		if sErr := objAPI.Shutdown(); sErr != nil {
-			return exitFailure
-		}
-		return exitSuccess
-	})
-
-	// Initialize a new event notifier.
-	err = initEventNotifier(objAPI)
-	fatalIf(err, "Unable to initialize event notification queue")
-
-	// Initialize a new bucket policies.
-	err = initBucketPolicies(objAPI)
-	fatalIf(err, "Unable to load all bucket policies")
-
 	// Initialize router.
 	mux := router.NewRouter()
 
 	// Register all routers.
-	registerStorageRPCRouter(mux, storageRPC)
+	registerStorageRPCRouters(mux, storageRPCs)
+	initDistributedNSLock(mux, srvCmdConfig)
 
 	// FIXME: till net/rpc auth is brought in "minio control" can be enabled only though
 	// this env variable.

cmd/rpc-client.go

@@ -19,6 +19,8 @@ package cmd
 import (
 	"net/http"
 	"net/rpc"
+	"path"
+	"strconv"
 	"strings"
 	"time"
 )
@@ -78,12 +80,6 @@ func newRPCClient(networkPath string) (StorageAPI, error) {
 	// TODO validate netAddr and netPath.
 	netAddr, netPath := splitNetPath(networkPath)
 
-	// Dial minio rpc storage http path.
-	rpcClient, err := rpc.DialHTTPPath("tcp", netAddr, storageRPCPath)
-	if err != nil {
-		return nil, err
-	}
-
 	// Initialize http client.
 	httpClient := &http.Client{
 		// Setting a sensible time out of 6minutes to wait for
@@ -93,6 +89,15 @@ func newRPCClient(networkPath string) (StorageAPI, error) {
 		Transport: http.DefaultTransport,
 	}
 
+	// Dial minio rpc storage http path.
+	rpcPath := path.Join(storageRPCPath, netPath)
+	port := getPort(srvConfig.serverAddr)
+	rpcAddr := netAddr + ":" + strconv.Itoa(port)
+	rpcClient, err := rpc.DialHTTPPath("tcp", rpcAddr, rpcPath)
+	if err != nil {
+		return nil, err
+	}
+
 	// Initialize network storage.
 	ndisk := &networkStorage{
 		netScheme:  "http", // TODO: fix for ssl rpc support.
@@ -108,6 +113,9 @@ func newRPCClient(networkPath string) (StorageAPI, error) {
 
 // MakeVol - make a volume.
 func (n networkStorage) MakeVol(volume string) error {
+	if n.rpcClient == nil {
+		return errVolumeBusy
+	}
 	reply := GenericReply{}
 	if err := n.rpcClient.Call("Storage.MakeVolHandler", volume, &reply); err != nil {
 		return toStorageErr(err)
@@ -117,6 +125,9 @@ func (n networkStorage) MakeVol(volume string) error {
 
 // ListVols - List all volumes.
 func (n networkStorage) ListVols() (vols []VolInfo, err error) {
+	if n.rpcClient == nil {
+		return nil, errVolumeBusy
+	}
 	ListVols := ListVolsReply{}
 	err = n.rpcClient.Call("Storage.ListVolsHandler", "", &ListVols)
 	if err != nil {
@@ -127,6 +138,9 @@ func (n networkStorage) ListVols() (vols []VolInfo, err error) {
 
 // StatVol - get current Stat volume info.
 func (n networkStorage) StatVol(volume string) (volInfo VolInfo, err error) {
+	if n.rpcClient == nil {
+		return VolInfo{}, errVolumeBusy
+	}
 	if err = n.rpcClient.Call("Storage.StatVolHandler", volume, &volInfo); err != nil {
 		return VolInfo{}, toStorageErr(err)
 	}
@@ -135,6 +149,9 @@ func (n networkStorage) StatVol(volume string) (volInfo VolInfo, err error) {
 
 // DeleteVol - Delete a volume.
 func (n networkStorage) DeleteVol(volume string) error {
+	if n.rpcClient == nil {
+		return errVolumeBusy
+	}
 	reply := GenericReply{}
 	if err := n.rpcClient.Call("Storage.DeleteVolHandler", volume, &reply); err != nil {
 		return toStorageErr(err)
@@ -146,6 +163,9 @@ func (n networkStorage) DeleteVol(volume string) error {
 
 // CreateFile - create file.
 func (n networkStorage) AppendFile(volume, path string, buffer []byte) (err error) {
+	if n.rpcClient == nil {
+		return errVolumeBusy
+	}
 	reply := GenericReply{}
 	if err = n.rpcClient.Call("Storage.AppendFileHandler", AppendFileArgs{
 		Vol:    volume,
@@ -184,6 +204,9 @@ func (n networkStorage) ReadAll(volume, path string) (buf []byte, err error) {
 
 // ReadFile - reads a file.
 func (n networkStorage) ReadFile(volume string, path string, offset int64, buffer []byte) (m int64, err error) {
+	if n.rpcClient == nil {
+		return 0, errVolumeBusy
+	}
 	if err = n.rpcClient.Call("Storage.ReadFileHandler", ReadFileArgs{
 		Vol:    volume,
 		Path:   path,
@@ -197,6 +220,9 @@ func (n networkStorage) ReadFile(volume string, path string, offset int64, buffe
 
 // ListDir - list all entries at prefix.
 func (n networkStorage) ListDir(volume, path string) (entries []string, err error) {
+	if n.rpcClient == nil {
+		return nil, errVolumeBusy
+	}
 	if err = n.rpcClient.Call("Storage.ListDirHandler", ListDirArgs{
 		Vol:  volume,
 		Path: path,
@@ -209,6 +235,9 @@ func (n networkStorage) ListDir(volume, path string) (entries []string, err erro
 
 // DeleteFile - Delete a file at path.
 func (n networkStorage) DeleteFile(volume, path string) (err error) {
+	if n.rpcClient == nil {
+		return errVolumeBusy
+	}
 	reply := GenericReply{}
 	if err = n.rpcClient.Call("Storage.DeleteFileHandler", DeleteFileArgs{
 		Vol:  volume,
@@ -221,6 +250,9 @@ func (n networkStorage) DeleteFile(volume, path string) (err error) {
 
 // RenameFile - Rename file.
 func (n networkStorage) RenameFile(srcVolume, srcPath, dstVolume, dstPath string) (err error) {
+	if n.rpcClient == nil {
+		return errVolumeBusy
+	}
 	reply := GenericReply{}
 	if err = n.rpcClient.Call("Storage.RenameFileHandler", RenameFileArgs{
 		SrcVol:  srcVolume,

cmd/rpc-server.go

@@ -1,7 +1,25 @@
-package cmd
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
 
 import (
 	"net/rpc"
+	"path"
+	"strings"
 
 	router "github.com/gorilla/mux"
 )
@@ -10,6 +28,7 @@ import (
 // disk over a network.
 type storageServer struct {
 	storage StorageAPI
+	path    string
 }
 
 /// Volume operations handlers
@@ -103,22 +122,50 @@ func (s *storageServer) RenameFileHandler(arg *RenameFileArgs, reply *GenericRep
 }
 
 // Initialize new storage rpc.
-func newRPCServer(exportPath string) (*storageServer, error) {
+func newRPCServer(serverConfig serverCmdConfig) (servers []*storageServer, err error) {
 	// Initialize posix storage API.
-	storage, err := newPosix(exportPath)
+	exports := serverConfig.disks
-	if err != nil && err != errDiskNotFound {
+	ignoredExports := serverConfig.ignoredDisks
-		return nil, err
+
+	// Save ignored disks in a map
+	skipDisks := make(map[string]bool)
+	for _, ignoredExport := range ignoredExports {
+		skipDisks[ignoredExport] = true
 	}
-	return &storageServer{
+	for _, export := range exports {
-		storage: storage,
+		if skipDisks[export] {
-	}, nil
+			continue
+		}
+		// e.g server:/mnt/disk1
+		if isLocalStorage(export) {
+			if idx := strings.LastIndex(export, ":"); idx != -1 {
+				export = export[idx+1:]
+			}
+			var storage StorageAPI
+			storage, err = newPosix(export)
+			if err != nil && err != errDiskNotFound {
+				return nil, err
+			}
+			if idx := strings.LastIndex(export, ":"); idx != -1 {
+				export = export[idx+1:]
+			}
+			servers = append(servers, &storageServer{
+				storage: storage,
+				path:    export,
+			})
+		}
+	}
+	return servers, err
 }
 
 // registerStorageRPCRouter - register storage rpc router.
-func registerStorageRPCRouter(mux *router.Router, stServer *storageServer) {
+func registerStorageRPCRouters(mux *router.Router, stServers []*storageServer) {
 	storageRPCServer := rpc.NewServer()
-	storageRPCServer.RegisterName("Storage", stServer)
+	// Create a unique route for each disk exported from this node.
-	storageRouter := mux.NewRoute().PathPrefix(reservedBucket).Subrouter()
+	for _, stServer := range stServers {
-	// Add minio storage routes.
+		storageRPCServer.RegisterName("Storage", stServer)
-	storageRouter.Path("/storage").Handler(storageRPCServer)
+		// Add minio storage routes.
+		storageRouter := mux.PathPrefix(reservedBucket).Subrouter()
+		storageRouter.Path(path.Join("/storage", stServer.path)).Handler(storageRPCServer)
+	}
 }

cmd/server-main.go

@@ -28,6 +28,7 @@ import (
 	"github.com/minio/cli"
 )
 
+var srvConfig serverCmdConfig
 var serverCmd = cli.Command{
 	Name:  "server",
 	Usage: "Start object storage server.",
@@ -245,11 +246,13 @@ func serverMain(c *cli.Context) {
 	disks := c.Args()
 
 	// Configure server.
-	handler := configureServerHandler(serverCmdConfig{
+	srvConfig = serverCmdConfig{
 		serverAddr:   serverAddress,
 		disks:        disks,
 		ignoredDisks: ignoredDisks,
-	})
+	}
+	// Configure server.
+	handler := configureServerHandler(srvConfig)
 
 	apiServer := NewServerMux(serverAddress, handler)
 

cmd/storage-errors.go

@@ -59,3 +59,6 @@ var errVolumeAccessDenied = errors.New("volume access denied")
 
 // errVolumeAccessDenied - cannot access file, insufficient permissions.
 var errFileAccessDenied = errors.New("file access denied")
+
+// errVolumeBusy - remote disk is not connected to yet.
+var errVolumeBusy = errors.New("volume is busy")

cmd/test-utils_test.go

@@ -888,7 +888,7 @@ func initTestAPIEndPoints(objLayer ObjectLayer, apiFunctions []string) http.Hand
 	// All object storage operations are registered as HTTP handlers on `objectAPIHandlers`.
 	// When the handlers get a HTTP request they use the underlyting ObjectLayer to perform operations.
 	api := objectAPIHandlers{
-		ObjectAPI: objLayer,
+		ObjectAPI: func() ObjectLayer { return objLayer },
 	}
 	// API Router.
 	apiRouter := muxRouter.NewRoute().PathPrefix("/").Subrouter()

cmd/web-handlers.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -124,7 +125,11 @@ func (web *webAPIHandlers) StorageInfo(r *http.Request, args *GenericArgs, reply
 		return &json2.Error{Message: "Unauthorized request"}
 	}
 	reply.UIVersion = miniobrowser.UIVersion
-	reply.StorageInfo = web.ObjectAPI.StorageInfo()
+	objectAPI := web.ObjectAPI()
+	if objectAPI == nil {
+		return &json2.Error{Message: "Volume not found"}
+	}
+	reply.StorageInfo = objectAPI.StorageInfo()
 	return nil
 }
 
@@ -139,7 +144,11 @@ func (web *webAPIHandlers) MakeBucket(r *http.Request, args *MakeBucketArgs, rep
 		return &json2.Error{Message: "Unauthorized request"}
 	}
 	reply.UIVersion = miniobrowser.UIVersion
-	if err := web.ObjectAPI.MakeBucket(args.BucketName); err != nil {
+	objectAPI := web.ObjectAPI()
+	if objectAPI == nil {
+		return &json2.Error{Message: "Volume not found"}
+	}
+	if err := objectAPI.MakeBucket(args.BucketName); err != nil {
 		return &json2.Error{Message: err.Error()}
 	}
 	return nil
@@ -164,7 +173,11 @@ func (web *webAPIHandlers) ListBuckets(r *http.Request, args *WebGenericArgs, re
 	if !isJWTReqAuthenticated(r) {
 		return &json2.Error{Message: "Unauthorized request"}
 	}
-	buckets, err := web.ObjectAPI.ListBuckets()
+	objectAPI := web.ObjectAPI()
+	if objectAPI == nil {
+		return &json2.Error{Message: "Volume not found"}
+	}
+	buckets, err := objectAPI.ListBuckets()
 	if err != nil {
 		return &json2.Error{Message: err.Error()}
 	}
@@ -212,7 +225,11 @@ func (web *webAPIHandlers) ListObjects(r *http.Request, args *ListObjectsArgs, r
 		return &json2.Error{Message: "Unauthorized request"}
 	}
 	for {
-		lo, err := web.ObjectAPI.ListObjects(args.BucketName, args.Prefix, marker, "/", 1000)
+		objectAPI := web.ObjectAPI()
+		if objectAPI == nil {
+			return &json2.Error{Message: "Volume not found"}
+		}
+		lo, err := objectAPI.ListObjects(args.BucketName, args.Prefix, marker, "/", 1000)
 		if err != nil {
 			return &json2.Error{Message: err.Error()}
 		}
@@ -250,7 +267,11 @@ func (web *webAPIHandlers) RemoveObject(r *http.Request, args *RemoveObjectArgs,
 		return &json2.Error{Message: "Unauthorized request"}
 	}
 	reply.UIVersion = miniobrowser.UIVersion
-	if err := web.ObjectAPI.DeleteObject(args.BucketName, args.ObjectName); err != nil {
+	objectAPI := web.ObjectAPI()
+	if objectAPI == nil {
+		return &json2.Error{Message: "Volume not found"}
+	}
+	if err := objectAPI.DeleteObject(args.BucketName, args.ObjectName); err != nil {
 		return &json2.Error{Message: err.Error()}
 	}
 	return nil
@@ -384,13 +405,18 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
 	// Extract incoming metadata if any.
 	metadata := extractMetadataFromHeader(r.Header)
 
-	if _, err := web.ObjectAPI.PutObject(bucket, object, -1, r.Body, metadata); err != nil {
+	objectAPI := web.ObjectAPI()
+	if objectAPI == nil {
+		writeWebErrorResponse(w, errors.New("Volume not found"))
+		return
+	}
+	if _, err := objectAPI.PutObject(bucket, object, -1, r.Body, metadata); err != nil {
 		writeWebErrorResponse(w, err)
 		return
 	}
 
 	// Fetch object info for notifications.
-	objInfo, err := web.ObjectAPI.GetObjectInfo(bucket, object)
+	objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
 		errorIf(err, "Unable to fetch object info for \"%s\"", path.Join(bucket, object))
 		return
@@ -435,13 +461,18 @@ 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)))
 
-	objInfo, err := web.ObjectAPI.GetObjectInfo(bucket, object)
+	objectAPI := web.ObjectAPI()
+	if objectAPI == nil {
+		writeWebErrorResponse(w, errors.New("Volume not found"))
+		return
+	}
+	objInfo, err := objectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
 		writeWebErrorResponse(w, err)
 		return
 	}
 	offset := int64(0)
-	err = web.ObjectAPI.GetObject(bucket, object, offset, objInfo.Size, w)
+	err = objectAPI.GetObject(bucket, object, offset, objInfo.Size, w)
 	if err != nil {
 		/// No need to print error, response writer already written to.
 		return

cmd/web-router.go

@@ -30,7 +30,7 @@ import (
 
 // webAPI container for Web API.
 type webAPIHandlers struct {
-	ObjectAPI ObjectLayer
+	ObjectAPI func() ObjectLayer
 }
 
 // indexHandler - Handler to serve index.html

cmd/xl-v1.go

@@ -118,6 +118,10 @@ func newXLObjects(disks, ignoredDisks []string) (ObjectLayer, error) {
 		// to handle these errors internally.
 		storageDisks[index], err = newStorageAPI(disk)
 		if err != nil && err != errDiskNotFound {
+			switch diskType := storageDisks[index].(type) {
+			case networkStorage:
+				diskType.rpcClient.Close()
+			}
 			return nil, err
 		}
 	}

lock-rpc-server.go

@@ -0,0 +1,107 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
+
+import (
+	"fmt"
+	"net/rpc"
+	"path"
+	"strings"
+	"sync"
+
+	router "github.com/gorilla/mux"
+)
+
+const lockRPCPath = "/lock"
+
+type lockServer struct {
+	rpcPath string
+	mutex   sync.Mutex
+	lockMap map[string]struct{}
+}
+
+///  Distributed lock handlers
+
+// LockHandler - rpc handler for lock operation.
+func (l *lockServer) LockHandler(name *string, reply *bool) error {
+	l.mutex.Lock()
+	defer l.mutex.Unlock()
+	_, ok := l.lockMap[*name]
+	if !ok {
+		*reply = true
+		l.lockMap[*name] = struct{}{}
+		return nil
+	}
+	*reply = false
+	return nil
+}
+
+// UnlockHandler - rpc handler for unlock operation.
+func (l *lockServer) UnlockHandler(name *string, reply *bool) error {
+	l.mutex.Lock()
+	defer l.mutex.Unlock()
+	_, ok := l.lockMap[*name]
+	if !ok {
+		return fmt.Errorf("Unlock attempted on an un-locked entity: %s", *name)
+	}
+	*reply = true
+	delete(l.lockMap, *name)
+	return nil
+}
+
+// Initialize distributed lock.
+func initDistributedNSLock(mux *router.Router, serverConfig serverCmdConfig) {
+	lockServers := newLockServers(serverConfig)
+	registerStorageLockers(mux, lockServers)
+}
+
+// Create one lock server for every local storage rpc server.
+func newLockServers(serverConfig serverCmdConfig) (lockServers []*lockServer) {
+	// Initialize posix storage API.
+	exports := serverConfig.disks
+	ignoredExports := serverConfig.ignoredDisks
+
+	// Save ignored disks in a map
+	skipDisks := make(map[string]bool)
+	for _, ignoredExport := range ignoredExports {
+		skipDisks[ignoredExport] = true
+	}
+	for _, export := range exports {
+		if skipDisks[export] {
+			continue
+		}
+		if idx := strings.LastIndex(export, ":"); idx != -1 {
+			export = export[idx+1:]
+		}
+		lockServers = append(lockServers, &lockServer{
+			rpcPath: export,
+			mutex:   sync.Mutex{},
+			lockMap: make(map[string]struct{}),
+		})
+	}
+	return lockServers
+}
+
+// registerStorageLockers - register locker rpc handlers for valyala/gorpc library clients
+func registerStorageLockers(mux *router.Router, lockServers []*lockServer) {
+	lockRPCServer := rpc.NewServer()
+	for _, lockServer := range lockServers {
+		lockRPCServer.RegisterName("Dsync", lockServer)
+		lockRouter := mux.PathPrefix(reservedBucket).Subrouter()
+		lockRouter.Path(path.Join("/lock", lockServer.rpcPath)).Handler(lockRPCServer)
+	}
+}

vendor/github.com/minio/dsync/LICENSE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
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vendor/github.com/minio/dsync/README.md

@@ -0,0 +1,81 @@
+dsync
+=====
+
+A distributed sync package.
+
+Introduction
+------------
+ 
+`dsync` is a package for doing distributed locks over a network of `n` nodes. It is designed with simplicity in mind and hence offers limited scalability (`n <= 16`). Each node will be connected to all other nodes and lock requests from any node will be broadcast to all connected nodes. A node will succeed in getting the lock if `n/2 + 1` nodes (including itself) respond positively. If the lock is acquired it can be held for some time and needs to be released afterwards. This will cause the release to be broadcast to all nodes after which the lock becomes available again.
+
+Design goals
+------------
+
+* Simple design: by keeping the design simple, many tricky edge cases can be avoided.
+* No master node: there is no concept of a master node which, if this would be used and the master would be down, causes locking to come to a complete stop. (Unless you have a design with a slave node but this adds yet more complexity.)
+* Resilient: if one or more nodes go down, the other nodes should not be affected and can continue to acquire locks (provided not more than `n/2 - 1` nodes are down).
+* Automatically reconnect to (restarted) nodes.
+* Compatible with `sync/mutex` API.
+
+
+Restrictions
+------------
+
+* Limited scalability: up to 16 nodes.
+* Fixed configuration: changes in the number and/or network names/IP addresses need a restart of all nodes in order to take effect.
+* If a down node comes up, it will not in any way (re)acquire any locks that it may have held.
+* Not designed for high performance applications such as key/value stores 
+
+Performance
+-----------
+
+* Lock requests (successful) should not take longer than 1ms (provided decent network connection of 1 Gbit or more between the nodes)
+* Support up to 4000 locks per node per second. 
+* Scale linearly with the number of locks. For the maximum size case of 16 nodes this means a maximum of 64K locks/sec (and 2048K lock request & release messages/sec)
+* Do not take more than (overall) 10% CPU usage
+
+Issues
+------
+
+* In case the node that has the lock goes down, the lock release will not be broadcast: what do we do? (periodically ping 'back' to requesting node from all nodes that have the lock?) Or detect that the network connection has gone down. 
+* If one of the nodes that participated in the lock goes down, this is not a problem since (when it comes back online) the node that originally acquired the lock will still have it, and a request for a new lock will fail due to only `n/2` being available.
+* If two nodes go down and both participated in the lock then there is a chance that a new lock will acquire locks from `n/2 + 1` nodes and will success, so we would have two concurrent locks. One way to counter this would be to monitor the network connections from the nodes that originated the lock, and, upon losing a connection to a node that granted a lock, get a new lock from a free node.  
+* When two nodes want to acquire the same lock, it is possible for both to just acquire `n` locks and there is no majority winner so both would fail (and presumably fail back to their clients?). This then requires a retry in order to acquire the lock at a later time.
+* What if late acquire response still comes in after lock has been obtained (quorum is in) and has already been released again. 
+
+Comparison to other techniques
+------------------------------
+
+We are well aware that there are more sophisticated systems such as zookeeper, raft, etc but we found that for our limited use case this was adding too much complexity. So if `dsync` does not meet your requirements than you are probably better off using one of those systems.
+
+Performance
+-----------
+
+```
+benchmark                       old ns/op     new ns/op     delta
+BenchmarkMutexUncontended-8     4.22          1164018       +27583264.93%
+BenchmarkMutex-8                96.5          1223266       +1267533.16%
+BenchmarkMutexSlack-8           120           1192900       +993983.33%
+BenchmarkMutexWork-8            108           1239893       +1147949.07%
+BenchmarkMutexWorkSlack-8       142           1210129       +852103.52%
+BenchmarkMutexNoSpin-8          292           319479        +109310.62%
+BenchmarkMutexSpin-8            1163          1270066       +109106.02%
+```
+
+Usage
+-----
+
+Explain usage
+```
+```
+
+
+License
+-------
+
+Released under the Apache License v2.0. You can find the complete text in the file LICENSE.
+
+Contributing
+------------
+
+Contributions are welcome, please send PRs for any enhancements.

vendor/github.com/minio/dsync/dmutex.go

@@ -0,0 +1,311 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dsync
+
+import (
+	"log"
+	"math"
+	"math/rand"
+	"net/rpc"
+	"strings"
+	"sync"
+	"time"
+)
+
+const DMutexAcquireTimeout = 25 * time.Millisecond
+
+// A DMutex is a distributed mutual exclusion lock.
+type DMutex struct {
+	Name  string
+	locks []bool     // Array of nodes that granted a lock
+	uids  []string   // Array of uids for verification of sending correct release messages
+	m     sync.Mutex // Mutex to prevent multiple simultaneous locks from this node
+
+	// TODO: Decide: create per object or create once for whole class
+	clnts []*rpc.Client
+}
+
+type Granted struct {
+	index  int
+	locked bool
+	uid    string
+}
+
+func connectLazy(dm *DMutex) {
+	if dm.clnts == nil {
+		dm.clnts = make([]*rpc.Client, n)
+	}
+	for i := range dm.clnts {
+		if dm.clnts[i] == nil {
+			// pass in unique path (as required by server.HandleHTTP()
+			dm.clnts[i], _ = rpc.DialHTTPPath("tcp", nodes[i], rpcPath+"-"+strings.Split(nodes[i], ":")[1])
+		}
+	}
+}
+
+// Lock locks dm.
+//
+// If the lock is already in use, the calling goroutine
+// blocks until the mutex is available.
+func (dm *DMutex) Lock() {
+
+	// Shield Lock() with local mutex in order to prevent more than
+	// one broadcast going out at the same time from this node
+	dm.m.Lock()
+	defer dm.m.Unlock()
+
+	runs, backOff := 1, 1
+
+	for {
+		// TODO: Implement reconnect
+		connectLazy(dm)
+
+		// create temp arrays on stack
+		locks := make([]bool, n)
+		ids := make([]string, n)
+
+		// try to acquire the lock
+		success := lock(dm.clnts, &locks, &ids, dm.Name)
+		if success {
+			// if success, copy array to object
+			dm.locks = make([]bool, n)
+			copy(dm.locks, locks[:])
+			dm.uids = make([]string, n)
+			copy(dm.uids, ids[:])
+			return
+		}
+
+		// We timed out on the previous lock, incrementally wait for a longer back-off time,
+		// and try again afterwards
+		time.Sleep(time.Duration(backOff) * time.Millisecond)
+
+		backOff += int(rand.Float64() * math.Pow(2, float64(runs)))
+		if backOff > 1024 {
+			backOff = backOff % 64
+
+			runs = 1 // reset runs
+		} else if runs < 10 {
+			runs++
+		}
+	}
+}
+
+func (dm *DMutex) tryLockTimeout() bool {
+
+	// Shield Lock() with local mutex in order to prevent more than
+	// one broadcast going out at the same time from this node
+	dm.m.Lock()
+	defer dm.m.Unlock()
+
+	// TODO: Implement reconnect
+	connectLazy(dm)
+
+	// create temp arrays on stack
+	locks := make([]bool, n)
+	ids := make([]string, n)
+
+	// try to acquire the lock
+	success := lock(dm.clnts, &locks, &ids, dm.Name)
+	if success {
+		// if success, copy array to object
+		dm.locks = make([]bool, n)
+		copy(dm.locks, locks[:])
+		dm.uids = make([]string, n)
+		copy(dm.uids, ids[:])
+	}
+	return success
+}
+
+// lock tries to acquire the distributed lock, returning true or false
+//
+func lock(clnts []*rpc.Client, locks *[]bool, uids *[]string, lockName string) bool {
+
+	// Create buffered channel of quorum size
+	ch := make(chan Granted, n/2+1)
+
+	for index, c := range clnts {
+
+		if c == nil {
+			continue
+		}
+		// broadcast lock request to all nodes
+		go func(index int, c *rpc.Client) {
+			// All client methods issuing RPCs are thread-safe and goroutine-safe,
+			// i.e. it is safe to call them from multiple concurrently running go routines.
+			var status bool
+			err := c.Call("Dsync.Lock", lockName, &status)
+
+			locked, uid := false, ""
+			if err == nil {
+				locked = status
+				// TODO: Get UIOD again
+				uid = ""
+			} else {
+				// silently ignore error, retry later
+			}
+
+			ch <- Granted{index: index, locked: locked, uid: uid}
+
+		}(index, c)
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	quorum := false
+
+	go func() {
+
+		// Wait until we have received (minimally) quorum number of responses or timeout
+		i := 0
+		done := false
+		timeout := time.After(DMutexAcquireTimeout)
+
+		for ; i < n; i++ {
+
+			select {
+			case grant := <-ch:
+				if grant.locked {
+					// Mark that this node has acquired the lock
+					(*locks)[grant.index] = true
+					(*uids)[grant.index] = grant.uid
+				} else {
+					done = true
+					//fmt.Println("one lock failed before quorum -- release locks acquired")
+					releaseAll(clnts, locks, uids, lockName)
+				}
+
+			case <-timeout:
+				done = true
+				// timeout happened, maybe one of the nodes is slow, count
+				// number of locks to check whether we have quorum or not
+				if !quorumMet(locks) {
+					//fmt.Println("timed out -- release locks acquired")
+					releaseAll(clnts, locks, uids, lockName)
+				}
+			}
+
+			if done {
+				break
+			}
+		}
+
+		// Count locks in order to determine whterh we have quorum or not
+		quorum = quorumMet(locks)
+
+		// Signal that we have the quorum
+		wg.Done()
+
+		// Wait for the other responses and immediately release the locks
+		// (do not add them to the locks array because the DMutex could
+		//  already has been unlocked again by the original calling thread)
+		for ; i < n; i++ {
+			grantToBeReleased := <-ch
+			if grantToBeReleased.locked {
+				// release lock
+				go sendRelease(clnts[grantToBeReleased.index], lockName, grantToBeReleased.uid)
+			}
+		}
+	}()
+
+	wg.Wait()
+
+	return quorum
+}
+
+// quorumMet determines whether we have acquired n/2+1 underlying locks or not
+func quorumMet(locks *[]bool) bool {
+
+	count := 0
+	for _, locked := range *locks {
+		if locked {
+			count++
+		}
+	}
+
+	return count >= n/2+1
+}
+
+// releaseAll releases all locks that are marked as locked
+func releaseAll(clnts []*rpc.Client, locks *[]bool, ids *[]string, lockName string) {
+
+	for lock := 0; lock < n; lock++ {
+		if (*locks)[lock] {
+			go sendRelease(clnts[lock], lockName, (*ids)[lock])
+			(*locks)[lock] = false
+			(*ids)[lock] = ""
+		}
+	}
+
+}
+
+// hasLock returns whether or not a node participated in granting the lock
+func (dm *DMutex) hasLock(node string) bool {
+
+	for index, n := range nodes {
+		if n == node {
+			return dm.locks[index]
+		}
+	}
+
+	return false
+}
+
+// locked returns whether or not we have met the quorum
+func (dm *DMutex) locked() bool {
+
+	locks := make([]bool, n)
+	copy(locks[:], dm.locks[:])
+
+	return quorumMet(&locks)
+}
+
+// Unlock unlocks dm.
+//
+// It is a run-time error if dm is not locked on entry to Unlock.
+func (dm *DMutex) Unlock() {
+
+	// Verify that we have the lock or panic otherwise (similar to sync.mutex)
+	if !dm.locked() {
+		panic("dsync: unlock of unlocked distributed mutex")
+	}
+
+	// We don't need to wait until we have released all the locks (or the quorum)
+	// (a subsequent lock will retry automatically in case it would fail to get
+	//  quorum)
+	for index, c := range dm.clnts {
+
+		if dm.locks[index] {
+			// broadcast lock release to all nodes the granted the lock
+			go sendRelease(c, dm.Name, dm.uids[index])
+
+			dm.locks[index] = false
+		}
+	}
+}
+
+// sendRelease sends a release message to a node that previously granted a lock
+func sendRelease(c *rpc.Client, name, uid string) {
+
+	// All client methods issuing RPCs are thread-safe and goroutine-safe,
+	// i.e. it is safe to call them from multiple concurrently running goroutines.
+	var status bool
+	// TODO: Send UID to server
+	if err := c.Call("Dsync.Unlock", name, &status); err != nil {
+		log.Fatal("Unlock on %s failed on client %v", name, c)
+	}
+}

vendor/github.com/minio/dsync/drwmutex.go

@@ -0,0 +1,143 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dsync
+
+import (
+	"fmt"
+	"sync"
+)
+
+const maxReaders = 8
+
+type DRWMutex struct {
+	rArray       []*DMutex
+	rLockedArray []bool
+	w            DMutex     // held if there are pending writers
+	m            sync.Mutex // Mutex to prevent multiple simultaneous locks from this node
+	m2           sync.Mutex // Mutex to prevent multiple simultaneous locks from this node
+}
+
+func NewDRWMutex(name string) (drw *DRWMutex) {
+
+	rArray := make([]*DMutex, maxReaders)
+	rLockedArray := make([]bool, maxReaders)
+
+	for r := 0; r < maxReaders; r++ {
+		rArray[r] = &DMutex{Name: fmt.Sprintf("%s-r%d", name, r)}
+	}
+
+	return &DRWMutex{
+		rArray:       rArray,
+		rLockedArray: rLockedArray,
+		w:            DMutex{Name: name + "-w"}}
+}
+
+// RLock locks drw for reading.
+func (drw *DRWMutex) RLock() {
+
+	drw.m.Lock()
+	defer drw.m.Unlock()
+
+	// Check if no write is active, block otherwise
+	// Can skip this?
+	drw.w.Lock()
+	drw.w.Unlock()
+
+	// Lock either one of the reader locks
+	for i := 0; ; i++ {
+		drw.rLockedArray[i%maxReaders] = drw.rArray[i%maxReaders].tryLockTimeout()
+		if drw.rLockedArray[i%maxReaders] {
+			return
+		}
+	}
+}
+
+// RUnlock undoes a single RLock call;
+// it does not affect other simultaneous readers.
+// It is a run-time error if rw is not locked for reading
+// on entry to RUnlock.
+func (drw *DRWMutex) RUnlock() {
+
+	drw.m.Lock()
+	defer drw.m.Unlock()
+
+	// Unlock whichever readlock that was acquired)
+	for r := 0; r < maxReaders; r++ {
+		if drw.rLockedArray[r] {
+			drw.rArray[r].Unlock()
+			drw.rLockedArray[r] = false
+			// we only want to release a single read lock at a time
+			break
+		}
+	}
+}
+
+// Lock locks rw for writing.
+// If the lock is already locked for reading or writing,
+// Lock blocks until the lock is available.
+// To ensure that the lock eventually becomes available,
+// a blocked Lock call excludes new readers from acquiring
+// the lock.
+func (drw *DRWMutex) Lock() {
+
+	drw.m.Lock()
+	defer drw.m.Unlock()
+
+	// First, resolve competition with other writers.
+	drw.w.Lock()
+
+	// Acquire all read locks.
+	var wg sync.WaitGroup
+	wg.Add(maxReaders)
+
+	for r := 0; r < maxReaders; r++ {
+		go func(r int) {
+			defer wg.Done()
+			drw.rArray[r].Lock()
+			drw.rLockedArray[r] = true
+		}(r)
+	}
+
+	wg.Wait()
+}
+
+// Unlock unlocks rw for writing.  It is a run-time error if rw is
+// not locked for writing on entry to Unlock.
+//
+// As with Mutexes, a locked RWMutex is not associated with a particular
+// goroutine.  One goroutine may RLock (Lock) an RWMutex and then
+// arrange for another goroutine to RUnlock (Unlock) it.
+func (drw *DRWMutex) Unlock() {
+
+	drw.m.Lock()
+	defer drw.m.Unlock()
+
+	for r := 0; r < maxReaders; r++ {
+		if !drw.rLockedArray[r] {
+			panic("dsync: unlock of unlocked distributed rwmutex")
+		}
+	}
+
+	// Unlock all read locks
+	for r := 0; r < maxReaders; r++ {
+		drw.rArray[r].Unlock()
+		drw.rLockedArray[r] = false
+	}
+
+	// Allow other writers to proceed.
+	drw.w.Unlock()
+}

vendor/github.com/minio/dsync/dsync.go

@@ -0,0 +1,56 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dsync
+
+import (
+	"errors"
+	"net/rpc"
+)
+
+const RpcPath = "/dsync"
+const DebugPath = "/debug"
+
+const DefaultPath = "/rpc/dsync"
+
+var n int
+var nodes []string
+var rpcPath string
+
+func closeClients(clients []*rpc.Client) {
+	for _, clnt := range clients {
+		clnt.Close()
+	}
+}
+
+// Same as SetNodes, but takes a path argument different from the package-level default.
+func SetNodesWithPath(nodeList []string, path string) (err error) {
+
+	// Validate if number of nodes is within allowable range.
+	if n != 0 {
+		return errors.New("Cannot reinitialize dsync package")
+	} else if len(nodeList) < 4 {
+		return errors.New("Dsync not designed for less than 4 nodes")
+	} else if len(nodeList) > 16 {
+		return errors.New("Dsync not designed for more than 16 nodes")
+	}
+
+	nodes = make([]string, len(nodeList))
+	copy(nodes, nodeList[:])
+	rpcPath = path
+	n = len(nodes)
+	return nil
+}

vendor/vendor.json

@@ -97,6 +97,12 @@
 			"revision": "c4a07c7b68db77ccd119183fb1d01dd5972434ab",
 			"revisionTime": "2015-11-18T20:00:48-08:00"
 		},
+		{
+			"checksumSHA1": "KCM0UiuvLA5fPiX5I83/HTklxlI=",
+			"path": "github.com/minio/dsync",
+			"revision": "c10eebd6b637bb834d502a6574c53e0ea6c64997",
+			"revisionTime": "2016-08-05T20:56:13Z"
+		},
 		{
 			"path": "github.com/minio/go-homedir",
 			"revision": "0b1069c753c94b3633cc06a1995252dbcc27c7a6",