Add device-mapper-specific block device properties

blockdevice/stats.go

@@ -16,13 +16,13 @@ package blockdevice
 import (
 	"bufio"
 	"fmt"
-	"github.com/prometheus/procfs/internal/util"
 	"io"
 	"io/ioutil"
 	"os"
 	"strings"
 
 	"github.com/prometheus/procfs/internal/fs"
+	"github.com/prometheus/procfs/internal/util"
 )
 
 // Info contains identifying information for a block device such as a disk drive
@@ -178,12 +178,37 @@ type BlockQueueStats struct {
 	WriteZeroesMaxBytes uint64
 }
 
+// DeviceMapperInfo models the devicemapper files that are located in the sysfs tree for each block device
+// and described in the kernel documentation:
+// https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-block-dm
+type DeviceMapperInfo struct {
+	// Name is the string containing mapped device name.
+	Name string
+	// RqBasedSeqIOMergeDeadline determines how long (in microseconds) a request that is a reasonable merge
+	// candidate can be queued on the request queue.
+	RqBasedSeqIOMergeDeadline uint64
+	// Suspended indicates if the device is suspended (1 is on, 0 is off).
+	Suspended uint64
+	// UseBlkMQ indicates if the device is using the request-based blk-mq I/O path mode (1 is on, 0 is off).
+	UseBlkMQ uint64
+	// UUID is the DM-UUID string or empty string if DM-UUID is not set.
+	UUID string
+}
+
+// UnderlyingDevices models the list of devices that this device is built from.
+type UnderlyingDeviceInfo struct {
+	// DeviceNames is the list of devices names
+	DeviceNames []string
+}
+
 const (
 	procDiskstatsPath   = "diskstats"
 	procDiskstatsFormat = "%d %d %s %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d"
 	sysBlockPath        = "block"
 	sysBlockStatFormat  = "%d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d"
 	sysBlockQueue       = "queue"
+	sysBlockDM          = "dm"
+	sysUnderlyingDev    = "slaves"
 )
 
 // FS represents the pseudo-filesystems proc and sys, which provides an
@@ -398,3 +423,44 @@ func (fs FS) SysBlockDeviceQueueStats(device string) (BlockQueueStats, error) {
 	}
 	return stat, nil
 }
+
+func (fs FS) SysBlockDeviceMapperInfo(device string) (DeviceMapperInfo, error) {
+	info := DeviceMapperInfo{}
+	// files with uint64 fields
+	for file, p := range map[string]*uint64{
+		"rq_based_seq_io_merge_deadline": &info.RqBasedSeqIOMergeDeadline,
+		"suspended":                      &info.Suspended,
+		"use_blk_mq":                     &info.UseBlkMQ,
+	} {
+		val, err := util.ReadUintFromFile(fs.sys.Path(sysBlockPath, device, sysBlockDM, file))
+		if err != nil {
+			return DeviceMapperInfo{}, err
+		}
+		*p = val
+	}
+	// files with string fields
+	for file, p := range map[string]*string{
+		"name": &info.Name,
+		"uuid": &info.UUID,
+	} {
+		val, err := util.SysReadFile(fs.sys.Path(sysBlockPath, device, sysBlockDM, file))
+		if err != nil {
+			return DeviceMapperInfo{}, err
+		}
+		*p = val
+	}
+	return info, nil
+}
+
+func (fs FS) SysBlockDeviceUnderlyingDevices(device string) (UnderlyingDeviceInfo, error) {
+	underlyingDir, err := os.Open(fs.sys.Path(sysBlockPath, device, sysUnderlyingDev))
+	if err != nil {
+		return UnderlyingDeviceInfo{}, err
+	}
+	underlying, err := underlyingDir.Readdirnames(0)
+	if err != nil {
+		return UnderlyingDeviceInfo{}, err
+	}
+	return UnderlyingDeviceInfo{DeviceNames: underlying}, nil
+
+}

blockdevice/stats_test.go

@@ -14,6 +14,7 @@
 package blockdevice
 
 import (
+	"os"
 	"reflect"
 	"testing"
 )
@@ -152,3 +153,69 @@ func TestBlockDevice(t *testing.T) {
 		t.Errorf("Incorrect BlockQueueStat, expected: \n%+v, got: \n%+v", blockQueueStatExpected, blockQueueStat)
 	}
 }
+
+func TestBlockDmInfo(t *testing.T) {
+	blockdevice, err := NewFS("../fixtures/proc", "../fixtures/sys")
+	if err != nil {
+		t.Fatalf("failed to access blockdevice fs: %v", err)
+	}
+	devices, err := blockdevice.SysBlockDevices()
+	if err != nil {
+		t.Fatal(err)
+	}
+	dm0Info, err := blockdevice.SysBlockDeviceMapperInfo(devices[0])
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dm0InfoExpected := DeviceMapperInfo{
+		Name:                      "vg0--lv_root",
+		RqBasedSeqIOMergeDeadline: 0,
+		Suspended:                 0,
+		UseBlkMQ:                  0,
+		UUID:                      "LVM-3zSHSR5Nbf4j7g6auAAefWY2CMaX01theZYEvQyecVsm2WtX3iY5q51qq5dWWOq7",
+	}
+	if !reflect.DeepEqual(dm0Info, dm0InfoExpected) {
+		t.Errorf("Incorrect BlockQueueStat, expected: \n%+v, got: \n%+v", dm0InfoExpected, dm0Info)
+	}
+
+	dm1Info, err := blockdevice.SysBlockDeviceMapperInfo(devices[1])
+	if err != nil {
+		if _, ok := err.(*os.PathError); ok {
+			// Fail the test if there's an error other than PathError.
+			if !os.IsNotExist(err) {
+				t.Fatal(err)
+			}
+		} else {
+			t.Fatal(err)
+		}
+	} else {
+		t.Fatal("SysBlockDeviceMapperInfo on sda was supposed to fail.")
+	}
+	dm1InfoExpected := DeviceMapperInfo{}
+	if !reflect.DeepEqual(dm1Info, dm1InfoExpected) {
+		t.Errorf("Incorrect BlockQueueStat, expected: \n%+v, got: \n%+v", dm0InfoExpected, dm0Info)
+	}
+}
+
+func TestSysBlockDeviceUnderlyingDevices(t *testing.T) {
+	blockdevice, err := NewFS("../fixtures/proc", "../fixtures/sys")
+	if err != nil {
+		t.Fatalf("failed to access blockdevice fs: %v", err)
+	}
+	devices, err := blockdevice.SysBlockDevices()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	underlying0, err := blockdevice.SysBlockDeviceUnderlyingDevices(devices[0])
+	if err != nil {
+		t.Fatal(err)
+	}
+	underlying0Expected := UnderlyingDeviceInfo{
+		DeviceNames: []string{"sda"},
+	}
+	if !reflect.DeepEqual(underlying0, underlying0Expected) {
+		t.Errorf("Incorrect BlockQueueStat, expected: \n%+v, got: \n%+v", underlying0Expected, underlying0)
+	}
+}

fixtures.ttar

@@ -3231,6 +3231,41 @@ Mode: 775
 Directory: fixtures/sys/block/dm-0
 Mode: 775
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/block/dm-0/dm
+Mode: 755
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/block/dm-0/dm/name
+Lines: 1
+vg0--lv_rootEOF
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/block/dm-0/dm/rq_based_seq_io_merge_deadline
+Lines: 1
+0EOF
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/block/dm-0/dm/suspended
+Lines: 1
+0EOF
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/block/dm-0/dm/use_blk_mq
+Lines: 1
+0EOF
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/block/dm-0/dm/uuid
+Lines: 1
+LVM-3zSHSR5Nbf4j7g6auAAefWY2CMaX01theZYEvQyecVsm2WtX3iY5q51qq5dWWOq7EOF
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/block/dm-0/slaves
+Mode: 755
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/block/dm-0/slaves/sda
+Lines: 0
+Mode: 664
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Path: fixtures/sys/block/dm-0/stat
 Lines: 1
 6447303        0 710266738  1529043   953216        0 31201176  4557464        0   796160  6088971
@@ -3478,6 +3513,27 @@ Mode: 664
 Directory: fixtures/sys/class
 Mode: 775
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/class/block
+Mode: 775
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/class/block/dm-0
+SymlinkTo: ../../devices/virtual/block/dm-0
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/class/block/dm-1
+SymlinkTo: ../../devices/virtual/block/dm-1
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/class/block/dm-2
+SymlinkTo: ../../devices/virtual/block/dm-2
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/class/block/dm-3
+SymlinkTo: ../../devices/virtual/block/dm-3
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/class/block/dm-4
+SymlinkTo: ../../devices/virtual/block/dm-4
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/sys/class/block/dm-5
+SymlinkTo: ../../devices/virtual/block/dm-5
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Directory: fixtures/sys/class/dmi
 Mode: 775
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -6491,6 +6547,15 @@ nr_zone_active_file 11
 nr_zone_unevictable 12
 Mode: 644
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/devices/virtual
+Mode: 775
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/devices/virtual/block
+Mode: 775
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/devices/virtual/block/dm-0
+Mode: 775
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Directory: fixtures/sys/fs
 Mode: 755
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -