Add ext4 stat package

Author: mshahzeb

blockdevice/stats.go

@@ -481,7 +481,7 @@ func (fs FS) SysBlockDeviceUnderlyingDevices(device string) (UnderlyingDeviceInf
 
 }
 
-// SysBlockDeviceIO returns stats for the block device read io counters
+// SysBlockDeviceIO returns stats for the block device io counters
 // IO done count: /sys/block/<disk>/device/iodone_cnt
 // IO error count: /sys/block/<disk>/device/ioerr_cnt
 func (fs FS) SysBlockDeviceIOStat(device string) (IODeviceStats, error) {

ext4/ext4.go

@@ -0,0 +1,103 @@
+// Copyright 2019 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 btrfs provides access to statistics exposed by ext4 filesystems.
+package ext4
+
+import (
+	"strings"
+	"path/filepath"
+
+	"github.com/prometheus/procfs/internal/fs"
+	"github.com/prometheus/procfs/internal/util"
+)
+
+const (
+	sysPath        = "sys"
+	sysFSPath        = "fs"
+)
+
+// Stats contains statistics for a single Btrfs filesystem.
+// See Linux fs/btrfs/sysfs.c for more information.
+type Stats struct {
+	Name           string
+
+	Errors         uint64
+	Warnings       uint64
+	Messages       uint64
+}
+
+// FS represents the pseudo-filesystems proc and sys, which provides an
+// interface to kernel data structures.
+type FS struct {
+	proc *fs.FS
+	sys  *fs.FS
+}
+
+// NewDefaultFS returns a new blockdevice fs using the default mountPoints for proc and sys.
+// It will error if either of these mount points can't be read.
+func NewDefaultFS() (FS, error) {
+	return NewFS(fs.DefaultProcMountPoint, fs.DefaultSysMountPoint)
+}
+
+// NewFS returns a new XFS handle using the given proc and sys mountPoints. It will error
+// if either of the mounts point can't be read.
+func NewFS(procMountPoint string, sysMountPoint string) (FS, error) {
+	if strings.TrimSpace(procMountPoint) == "" {
+		procMountPoint = fs.DefaultProcMountPoint
+	}
+	procfs, err := fs.NewFS(procMountPoint)
+	if err != nil {
+		return FS{}, err
+	}
+	if strings.TrimSpace(sysMountPoint) == "" {
+		sysMountPoint = fs.DefaultSysMountPoint
+	}
+	sysfs, err := fs.NewFS(sysMountPoint)
+	if err != nil {
+		return FS{}, err
+	}
+	return FS{&procfs, &sysfs}, nil
+}
+
+// ProcStat returns stats for the filesystem.
+func (fs FS) ProcStat() ([]*Stats, error) {
+	matches, err := filepath.Glob(fs.sys.Path("fs/ext4/*"))
+	if (err != nil) {
+			return nil, err
+	}
+
+	stats := make([]*Stats, 0, len(matches))
+	for _, m := range matches {
+			s := &Stats{}
+			for file, p := range map[string]*uint64{
+					"errors_count": &s.Errors,
+					"warning_count": &s.Warnings,
+					"msg_count": &s.Messages,
+			} {
+					var val uint64
+					val, err = util.ReadUintFromFile(fs.sys.Path(m, file))
+					if err != nil {
+							return nil, err
+					}
+					*p = val
+			}
+
+			// "*" used in glob above indicates the name of the filesystem.
+			name := filepath.Base(filepath.Dir(filepath.Dir(m)))
+			s.Name = name
+			stats = append(stats, s)
+	}
+
+	return stats, nil
+}