Add mkdonut command

cmd/mkdonut/disks.go

@@ -0,0 +1,56 @@
+/*
+ * Minimalist Object Storage, (C) 2015 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 (
+	"errors"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"syscall"
+
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// IsUsable provides a comprehensive way of knowing if the provided mountPath is mounted and writable
+func IsUsable(mountPath string) (bool, error) {
+	mntpoint, err := os.Stat(mountPath)
+	if err != nil {
+		return false, iodine.New(err, nil)
+	}
+	parent, err := os.Stat(filepath.Join(mountPath, ".."))
+	if err != nil {
+		return false, iodine.New(err, nil)
+	}
+	mntpointSt := mntpoint.Sys().(*syscall.Stat_t)
+	parentSt := parent.Sys().(*syscall.Stat_t)
+
+	if mntpointSt.Dev == parentSt.Dev {
+		return false, iodine.New(errors.New("not mounted"), nil)
+	}
+	testFile, err := ioutil.TempFile(mountPath, "writetest-")
+	if err != nil {
+		return false, iodine.New(err, nil)
+	}
+	testFileName := testFile.Name()
+	// close the file, to avoid leaky fd's
+	testFile.Close()
+	if err := os.Remove(testFileName); err != nil {
+		return false, iodine.New(err, nil)
+	}
+	return true, nil
+}