Add mountinfo functions for detecting mount disks, and other rpc changes

pkg/utils/scsi/mountinfo.go

@@ -0,0 +1,122 @@
+// +build linux
+
+/*
+ * Mini Object Storage, (C) 2014 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 scsi
+
+import (
+	"bufio"
+	"errors"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// Mountinfo container to capture /etc/mtab mount structure
+type Mountinfo struct {
+	FSName string /* name of mounted filesystem */
+	Dir    string /* filesystem path prefix */
+	Type   string /* mount type (see mntent.h) */
+	Opts   string /* mount options (see mntent.h) */
+	Freq   int    /* dump frequency in days */
+	Passno int    /* pass number on parallel fsck */
+}
+
+var supportedFSType = map[string]bool{
+	"ext4":  true,
+	"xfs":   true,
+	"ext3":  true,
+	"btrfs": true,
+	"tmpfs": true,
+	"nfs":   true,
+}
+
+func isSupportedType(t string) bool {
+	_, ok := supportedFSType[t]
+	return ok
+}
+
+// GetMountInfo - get mount info map
+func GetMountInfo() (map[string]Mountinfo, error) {
+	f, err := os.Open("/etc/mtab")
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	mntEnt := make(map[string]Mountinfo)
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		mtabEnt := strings.Split(scanner.Text(), " ")
+		mntInfo := Mountinfo{}
+		if len(mtabEnt) == 6 {
+			var err error
+			if !isSupportedType(mtabEnt[2]) {
+				continue
+			}
+			mntInfo.FSName, err = filepath.EvalSymlinks(mtabEnt[0])
+			if err != nil {
+				continue
+			}
+			mntInfo.Dir = mtabEnt[1]
+			mntInfo.Type = mtabEnt[2]
+			mntInfo.Opts = mtabEnt[3]
+			mntInfo.Freq, err = strconv.Atoi(mtabEnt[4])
+			if err != nil {
+				continue
+			}
+			mntInfo.Passno, err = strconv.Atoi(mtabEnt[5])
+			if err != nil {
+				continue
+			}
+			mntEnt[mntInfo.FSName] = mntInfo
+		}
+	}
+	return mntEnt, nil
+}
+
+// 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
+}

pkg/utils/scsi/scsi_test.go

@@ -34,3 +34,8 @@ func (s *MySuite) TestSCSI(c *C) {
 	_, err := GetDisks()
 	c.Assert(err, IsNil)
 }
+
+func (s *MySuite) TestMountInfo(c *C) {
+	_, err := GetMountInfo()
+	c.Assert(err, IsNil)
+}