objectLayer: Check for format.json in a wrapped disk. (#3311)

This is needed to validate if the `format.json` indeed exists
when a fresh node is brought online.

This wrapped implementation also connects to the remote node
by attempting a re-login. Subsequently after a successful
connect `format.json` is validated as well.

Fixes #3207

cmd/retry-storage.go

@@ -0,0 +1,224 @@
+/*
+ * 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 cmd
+
+import (
+	"net/rpc"
+
+	"github.com/minio/minio/pkg/disk"
+)
+
+// Retry storage is an instance of StorageAPI which
+// additionally verifies upon network shutdown if the
+// underlying storage is available and is really
+// formatted.
+type retryStorage struct {
+	remoteStorage StorageAPI
+}
+
+// String representation of remoteStorage.
+func (f retryStorage) String() string {
+	return f.remoteStorage.String()
+}
+
+// Reconncts to underlying remote storage.
+func (f retryStorage) Init() (err error) {
+	return f.remoteStorage.Init()
+}
+
+// Closes the underlying remote storage connection.
+func (f retryStorage) Close() (err error) {
+	return f.remoteStorage.Close()
+}
+
+// DiskInfo - a retryable implementation of disk info.
+func (f retryStorage) DiskInfo() (info disk.Info, err error) {
+	info, err = f.remoteStorage.DiskInfo()
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.DiskInfo()
+		}
+	}
+	return info, err
+}
+
+// MakeVol - a retryable implementation of creating a volume.
+func (f retryStorage) MakeVol(volume string) (err error) {
+	err = f.remoteStorage.MakeVol(volume)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.MakeVol(volume)
+		}
+	}
+	return err
+}
+
+// ListVols - a retryable implementation of listing all the volumes.
+func (f retryStorage) ListVols() (vols []VolInfo, err error) {
+	vols, err = f.remoteStorage.ListVols()
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.ListVols()
+		}
+	}
+	return vols, err
+}
+
+// StatVol - a retryable implementation of stating a volume.
+func (f retryStorage) StatVol(volume string) (vol VolInfo, err error) {
+	vol, err = f.remoteStorage.StatVol(volume)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.StatVol(volume)
+		}
+	}
+	return vol, err
+}
+
+// DeleteVol - a retryable implementation of deleting a volume.
+func (f retryStorage) DeleteVol(volume string) (err error) {
+	err = f.remoteStorage.DeleteVol(volume)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.DeleteVol(volume)
+		}
+	}
+	return err
+}
+
+// PrepareFile - a retryable implementation of preparing a file.
+func (f retryStorage) PrepareFile(volume, path string, length int64) (err error) {
+	err = f.remoteStorage.PrepareFile(volume, path, length)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.PrepareFile(volume, path, length)
+		}
+	}
+	return err
+}
+
+// AppendFile - a retryable implementation of append to a file.
+func (f retryStorage) AppendFile(volume, path string, buffer []byte) (err error) {
+	err = f.remoteStorage.AppendFile(volume, path, buffer)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.AppendFile(volume, path, buffer)
+		}
+	}
+	return err
+}
+
+// StatFile - a retryable implementation of stating a file.
+func (f retryStorage) StatFile(volume, path string) (fileInfo FileInfo, err error) {
+	fileInfo, err = f.remoteStorage.StatFile(volume, path)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.StatFile(volume, path)
+		}
+	}
+	return fileInfo, err
+}
+
+// ReadAll - a retryable implementation of reading all the content from a file.
+func (f retryStorage) ReadAll(volume, path string) (buf []byte, err error) {
+	buf, err = f.remoteStorage.ReadAll(volume, path)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.ReadAll(volume, path)
+		}
+	}
+	return buf, err
+}
+
+// ReadFile - a retryable implementation of reading at offset from a file.
+func (f retryStorage) ReadFile(volume, path string, offset int64, buffer []byte) (m int64, err error) {
+	m, err = f.remoteStorage.ReadFile(volume, path, offset, buffer)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.ReadFile(volume, path, offset, buffer)
+		}
+	}
+	return m, err
+}
+
+// ListDir - a retryable implementation of listing directory entries.
+func (f retryStorage) ListDir(volume, path string) (entries []string, err error) {
+	entries, err = f.remoteStorage.ListDir(volume, path)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.ListDir(volume, path)
+		}
+	}
+	return entries, err
+}
+
+// DeleteFile - a retryable implementation of deleting a file.
+func (f retryStorage) DeleteFile(volume, path string) (err error) {
+	err = f.remoteStorage.DeleteFile(volume, path)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.DeleteFile(volume, path)
+		}
+	}
+	return err
+}
+
+// Connect and attempt to load the format from a disconnected node.
+func (f retryStorage) reInit() (err error) {
+	err = f.remoteStorage.Close()
+	if err != nil {
+		return err
+	}
+	err = f.remoteStorage.Init()
+	if err == nil {
+		_, err = loadFormat(f.remoteStorage)
+		// For load format returning network shutdown
+		// we now treat it like disk not available.
+		if err == rpc.ErrShutdown {
+			err = errDiskNotFound
+		}
+		return err
+	}
+	if err == rpc.ErrShutdown {
+		err = errDiskNotFound
+	}
+	return err
+}
+
+// RenameFile - a retryable implementation of renaming a file.
+func (f retryStorage) RenameFile(srcVolume, srcPath, dstVolume, dstPath string) (err error) {
+	err = f.remoteStorage.RenameFile(srcVolume, srcPath, dstVolume, dstPath)
+	if err == rpc.ErrShutdown {
+		err = f.reInit()
+		if err == nil {
+			return f.remoteStorage.RenameFile(srcVolume, srcPath, dstVolume, dstPath)
+		}
+	}
+	return err
+}