diff --git a/vendor/github.com/prometheus/procfs/mdstat.go b/vendor/github.com/prometheus/procfs/mdstat.go
new file mode 100644
index 0000000..71c1067
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/mdstat.go
@@ -0,0 +1,151 @@
+// Copyright 2018 The Prometheus Authors
+// 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 procfs
+
+import (
+	"fmt"
+	"io/ioutil"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	statuslineRE = regexp.MustCompile(`(\d+) blocks .*\[(\d+)/(\d+)\] \[[U_]+\]`)
+	buildlineRE  = regexp.MustCompile(`\((\d+)/\d+\)`)
+)
+
+// MDStat holds info parsed from /proc/mdstat.
+type MDStat struct {
+	// Name of the device.
+	Name string
+	// activity-state of the device.
+	ActivityState string
+	// Number of active disks.
+	DisksActive int64
+	// Total number of disks the device consists of.
+	DisksTotal int64
+	// Number of blocks the device holds.
+	BlocksTotal int64
+	// Number of blocks on the device that are in sync.
+	BlocksSynced int64
+}
+
+// MDStat parses an mdstat-file (/proc/mdstat) and returns a slice of
+// structs containing the relevant info.  More information available here:
+// https://raid.wiki.kernel.org/index.php/Mdstat
+func (fs FS) MDStat() ([]MDStat, error) {
+	data, err := ioutil.ReadFile(fs.proc.Path("mdstat"))
+	if err != nil {
+		return nil, fmt.Errorf("error parsing mdstat %s: %s", fs.proc.Path("mdstat"), err)
+	}
+	mdstat, err := parseMDStat(data)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing mdstat %s: %s", fs.proc.Path("mdstat"), err)
+	}
+	return mdstat, nil
+}
+
+// parseMDStat parses data from mdstat file (/proc/mdstat) and returns a slice of
+// structs containing the relevant info.
+func parseMDStat(mdstatData []byte) ([]MDStat, error) {
+	mdStats := []MDStat{}
+	lines := strings.Split(string(mdstatData), "\n")
+	for i, l := range lines {
+		if strings.TrimSpace(l) == "" || l[0] == ' ' ||
+			strings.HasPrefix(l, "Personalities") || strings.HasPrefix(l, "unused") {
+			continue
+		}
+
+		deviceFields := strings.Fields(l)
+		if len(deviceFields) < 3 {
+			return nil, fmt.Errorf("not enough fields in mdline (expected at least 3): %s", l)
+		}
+		mdName := deviceFields[0]
+		activityState := deviceFields[2]
+
+		if len(lines) <= i+3 {
+			return mdStats, fmt.Errorf("missing lines for md device %s", mdName)
+		}
+
+		active, total, size, err := evalStatusLine(lines[i+1])
+		if err != nil {
+			return nil, err
+		}
+
+		syncLineIdx := i + 2
+		if strings.Contains(lines[i+2], "bitmap") { // skip bitmap line
+			syncLineIdx++
+		}
+
+		// If device is recovering/syncing at the moment, get the number of currently
+		// synced bytes, otherwise that number equals the size of the device.
+		syncedBlocks := size
+		if strings.Contains(lines[syncLineIdx], "recovery") || strings.Contains(lines[syncLineIdx], "resync") {
+			syncedBlocks, err = evalRecoveryLine(lines[syncLineIdx])
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		mdStats = append(mdStats, MDStat{
+			Name:          mdName,
+			ActivityState: activityState,
+			DisksActive:   active,
+			DisksTotal:    total,
+			BlocksTotal:   size,
+			BlocksSynced:  syncedBlocks,
+		})
+	}
+
+	return mdStats, nil
+}
+
+func evalStatusLine(statusline string) (active, total, size int64, err error) {
+	matches := statuslineRE.FindStringSubmatch(statusline)
+	if len(matches) != 4 {
+		return 0, 0, 0, fmt.Errorf("unexpected statusline: %s", statusline)
+	}
+
+	size, err = strconv.ParseInt(matches[1], 10, 64)
+	if err != nil {
+		return 0, 0, 0, fmt.Errorf("unexpected statusline %s: %s", statusline, err)
+	}
+
+	total, err = strconv.ParseInt(matches[2], 10, 64)
+	if err != nil {
+		return 0, 0, 0, fmt.Errorf("unexpected statusline %s: %s", statusline, err)
+	}
+
+	active, err = strconv.ParseInt(matches[3], 10, 64)
+	if err != nil {
+		return 0, 0, 0, fmt.Errorf("unexpected statusline %s: %s", statusline, err)
+	}
+
+	return active, total, size, nil
+}
+
+func evalRecoveryLine(buildline string) (syncedBlocks int64, err error) {
+	matches := buildlineRE.FindStringSubmatch(buildline)
+	if len(matches) != 2 {
+		return 0, fmt.Errorf("unexpected buildline: %s", buildline)
+	}
+
+	syncedBlocks, err = strconv.ParseInt(matches[1], 10, 64)
+	if err != nil {
+		return 0, fmt.Errorf("%s in buildline: %s", err, buildline)
+	}
+
+	return syncedBlocks, nil
+}