Properly detect dm devices

Fixes: #298
Signed-off-by: Avishay Traeger <avishay@redhat.com>

pkg/block/block.go

@@ -30,6 +30,7 @@ const (
 	DRIVE_TYPE_ODD               // Optical disk drive
 	DRIVE_TYPE_SSD               // Solid-state drive
 	DRIVE_TYPE_ISCSI             // iSCSI drive
+	DRIVE_TYPE_MAPPER            // Mapper device
 )
 
 var (
@@ -40,6 +41,7 @@ var (
 		DRIVE_TYPE_ODD:     "ODD",
 		DRIVE_TYPE_SSD:     "SSD",
 		DRIVE_TYPE_ISCSI:   "ISCSI",
+		DRIVE_TYPE_MAPPER:  "Mapper",
 	}
 
 	// NOTE(fromani): the keys are all lowercase and do not match
@@ -54,6 +56,7 @@ var (
 		"odd":     DRIVE_TYPE_ODD,
 		"ssd":     DRIVE_TYPE_SSD,
 		"iscsi":   DRIVE_TYPE_ISCSI,
+		"mapper":  DRIVE_TYPE_MAPPER,
 	}
 )
 
@@ -166,6 +169,7 @@ type Disk struct {
 	SerialNumber string       `json:"serial_number"`
 	WWN          string       `json:"wwn"`
 	Partitions   []*Partition `json:"partitions"`
+	Members      []string     `json:"members"`
 	// TODO(jaypipes): Add PCI field for accessing PCI device information
 	// PCI *PCIDevice `json:"pci"`
 }

pkg/block/block_linux.go

@@ -252,6 +252,19 @@ func diskIsRemovable(paths *linuxpath.Paths, disk string) bool {
 	return removable == "1"
 }
 
+func diskMembers(ctx *context.Context, paths *linuxpath.Paths, disk string) []string {
+	out := make([]string, 0)
+	path := filepath.Join(paths.SysBlock, disk, "slaves")
+	files, err := ioutil.ReadDir(path)
+	if err != nil {
+		return out
+	}
+	for _, file := range files {
+		out = append(out, file.Name())
+	}
+	return out
+}
+
 func disks(ctx *context.Context, paths *linuxpath.Paths) []*Disk {
 	// In Linux, we could use the fdisk, lshw or blockdev commands to list disk
 	// information, however all of these utilities require root privileges to
@@ -271,7 +284,7 @@ func disks(ctx *context.Context, paths *linuxpath.Paths) []*Disk {
 		driveType, storageController := diskTypes(dname)
 		// TODO(jaypipes): Move this into diskTypes() once abstracting
 		// diskIsRotational for ease of unit testing
-		if !diskIsRotational(ctx, paths, dname) {
+		if driveType != DRIVE_TYPE_MAPPER && !diskIsRotational(ctx, paths, dname) {
 			driveType = DRIVE_TYPE_SSD
 		}
 		size := diskSizeBytes(paths, dname)
@@ -286,6 +299,7 @@ func disks(ctx *context.Context, paths *linuxpath.Paths) []*Disk {
 		serialNo := diskSerialNumber(paths, dname)
 		wwn := diskWWN(paths, dname)
 		removable := diskIsRemovable(paths, dname)
+		members := diskMembers(ctx, paths, dname)
 
 		d := &Disk{
 			Name:                   dname,
@@ -300,6 +314,7 @@ func disks(ctx *context.Context, paths *linuxpath.Paths) []*Disk {
 			Model:                  model,
 			SerialNumber:           serialNo,
 			WWN:                    wwn,
+			Members:                members,
 		}
 
 		parts := diskPartitions(ctx, paths, dname)
@@ -348,6 +363,8 @@ func diskTypes(dname string) (
 	} else if strings.HasPrefix(dname, "mmc") {
 		driveType = DRIVE_TYPE_SSD
 		storageController = STORAGE_CONTROLLER_MMC
+	} else if strings.HasPrefix(dname, "dm-") {
+		driveType = DRIVE_TYPE_MAPPER
 	}
 
 	return driveType, storageController

pkg/block/block_linux_test.go

@@ -218,3 +218,45 @@ func TestISCSI(t *testing.T) {
 		t.Fatalf("Got drive type %s, but expected ISCSI", diskInventory[0].DriveType)
 	}
 }
+
+func TestMapper(t *testing.T) {
+	if _, ok := os.LookupEnv("GHW_TESTING_SKIP_BLOCK"); ok {
+		t.Skip("Skipping block tests.")
+	}
+
+	baseDir, _ := ioutil.TempDir("", "test")
+	defer os.RemoveAll(baseDir)
+	ctx := context.New()
+	ctx.Chroot = baseDir
+	paths := linuxpath.New(ctx)
+
+	_ = os.MkdirAll(paths.SysBlock, 0755)
+	_ = os.MkdirAll(paths.RunUdevData, 0755)
+	// Emulate a mapper device with no members
+	_ = os.Mkdir(filepath.Join(paths.SysBlock, "dm-0"), 0755)
+	_ = ioutil.WriteFile(filepath.Join(paths.SysBlock, "dm-0", "size"), []byte("419430400\n"), 0644)
+	_ = os.Mkdir(filepath.Join(paths.SysBlock, "dm-0", "queue"), 0755)
+	_ = ioutil.WriteFile(filepath.Join(paths.SysBlock, "dm-0", "queue", "rotational"), []byte("0\n"), 0644)
+	_ = ioutil.WriteFile(filepath.Join(paths.SysBlock, "dm-0", "queue", "physical_block_size"), []byte("512\n"), 0644)
+
+	diskInventory := disks(ctx, paths)
+	if diskInventory[0].DriveType != DRIVE_TYPE_MAPPER {
+		t.Fatalf("Got drive type %s, but expected Mapper", diskInventory[0].DriveType)
+	}
+	if len(diskInventory[0].Members) > 0 {
+		t.Fatalf("Got %d members but didn't expect any", len(diskInventory[0].Members))
+	}
+
+	// Add members (we create regular files here for brevity even though in reality they are symlinks)
+	_ = os.Mkdir(filepath.Join(paths.SysBlock, "dm-0", "slaves"), 0755)
+	_ = ioutil.WriteFile(filepath.Join(paths.SysBlock, "dm-0", "slaves", "sda"), []byte(""), 0644)
+	_ = ioutil.WriteFile(filepath.Join(paths.SysBlock, "dm-0", "slaves", "sdb"), []byte(""), 0644)
+
+	diskInventory = disks(ctx, paths)
+	if diskInventory[0].DriveType != DRIVE_TYPE_MAPPER {
+		t.Fatalf("Got drive type %s, but expected Mapper", diskInventory[0].DriveType)
+	}
+	if len(diskInventory[0].Members) != 2 {
+		t.Fatalf("Got %d members but expected 2", len(diskInventory[0].Members))
+	}
+}