fix: try to find cdrom disks

It fix helps to find non-partition file systems.

Signed-off-by: Serge Logvinov <serge.logvinov@sinextra.dev>
Signed-off-by: Artem Chernyshev <artem.chernyshev@talos-systems.com>

blockdevice/loopback/loopback.go

@@ -55,6 +55,21 @@ func Loop(loopbackDevice, image *os.File) error {
 		unix.LOOP_SET_FD,
 		image.Fd(),
 	)
+	if e := errnoIsErr(err); e != nil {
+		return e
+	}
+
+	// Force kernel to scan partition table on loop device
+	status := &unix.LoopInfo64{
+		Flags: unix.LO_FLAGS_PARTSCAN,
+	}
+
+	_, _, err = syscall.Syscall(
+		syscall.SYS_IOCTL,
+		loopbackDevice.Fd(),
+		unix.LOOP_SET_STATUS64,
+		uintptr(unsafe.Pointer(status)),
+	)
 
 	return errnoIsErr(err)
 }

blockdevice/probe/probe.go

@@ -103,15 +103,15 @@ func All(options ...SelectOption) (all []*ProbedBlockDevice, err error) {
 		probed := probePartitions(devpath)
 
 		for _, dev := range probed {
-			add := true
+			add := false
 			for _, matches := range options {
 				add, err = matches(dev)
 				if err != nil {
 					if e := dev.Close(); e != nil {
 						return nil, e
 					}
 
-					return nil, err
+					break
 				}
 
 				if !add {
@@ -151,6 +151,9 @@ func probe(devpath string) (devpaths []string) {
 	// file system exists without a partition table.
 	bd, err := blockdevice.Open(devpath, blockdevice.WithMode(blockdevice.ReadonlyMode))
 	if err != nil {
+		// Now blockdevice.Open returns error if it cannot read devpath
+		// I believe filesystem.Probe always return sb = nil
+		// but i keep it here. May be it will fix in future.
 		//nolint: errcheck
 		if sb, _ := filesystem.Probe(devpath); sb != nil {
 			devpaths = append(devpaths, devpath)
@@ -166,6 +169,13 @@ func probe(devpath string) (devpaths []string) {
 	// has partitions.
 	pt, err := bd.PartitionTable()
 	if err != nil {
+		// If a partition table was not found, it is still possible that a
+		// file system exists without a partition table.
+		//nolint: errcheck
+		if sb, _ := filesystem.Probe(devpath); sb != nil {
+			devpaths = append(devpaths, devpath)
+		}
+
 		return devpaths
 	}
 
@@ -231,6 +241,7 @@ func GetPartitionWithName(name string) (part *gpt.Partition, err error) {
 	return device.GetPartition(name)
 }
 
+// Returns array with partitions or root readable device.
 func probePartitions(devpath string) (probed []*ProbedBlockDevice) {
 	for _, path := range probe(devpath) {
 		var (

blockdevice/probe/probe_test.go

@@ -46,14 +46,39 @@ func (suite *ProbeSuite) addPartition(name string, size uint64) *gpt.Partition {
 	return partition
 }
 
-func (suite *ProbeSuite) TestGetPartitionWithName() {
+func (suite *ProbeSuite) setSystemLabel(name string) {
+	cmd := exec.Command("mkfs.vfat", "-F", "32", "-n", name, suite.LoopbackDevice.Name())
+	suite.Require().NoError(cmd.Run())
+}
+
+func (suite *ProbeSuite) TestDevForPartitionLabel() {
+	size := uint64(1024 * 1024 * 256)
+	part := suite.addPartition("devpart1", size)
+
+	dev, err := probe.DevForPartitionLabel(suite.LoopbackDevice.Name(), "devpart1")
+	suite.Require().NoError(err)
+	path, err := part.Path()
+	suite.Require().NoError(err)
+	suite.Require().Equal(path, dev.Device().Name())
+}
+
+func (suite *ProbeSuite) TestGetDevWithPartitionName() {
 	size := uint64(1024 * 1024 * 512)
-	part := suite.addPartition("label2", size)
+	part := suite.addPartition("devlabel", size)
 
-	_, err := probe.GetPartitionWithName("label2")
+	dev, err := probe.GetDevWithPartitionName("devlabel")
 	suite.Require().NoError(err)
-	_, err = part.Path()
+	devpath, err := part.Path()
 	suite.Require().NoError(err)
+	suite.Require().Equal(devpath, dev.Path)
+}
+
+func (suite *ProbeSuite) TestGetDevWithFileSystemLabel() {
+	suite.setSystemLabel("GETLABELSYS")
+
+	dev, err := probe.GetDevWithFileSystemLabel("GETLABELSYS")
+	suite.Require().NoError(err)
+	suite.Require().Equal(suite.LoopbackDevice.Name(), dev.Path)
 }
 
 func (suite *ProbeSuite) TestProbeByPartitionLabel() {
@@ -68,17 +93,6 @@ func (suite *ProbeSuite) TestProbeByPartitionLabel() {
 	suite.Require().Equal(suite.LoopbackDevice.Name(), probed[0].Device().Name())
 }
 
-func (suite *ProbeSuite) TestDevForPartitionLabel() {
-	size := uint64(1024 * 1024 * 256)
-	part := suite.addPartition("label1", size)
-
-	dev, err := probe.DevForPartitionLabel(suite.LoopbackDevice.Name(), "label1")
-	suite.Require().NoError(err)
-	path, err := part.Path()
-	suite.Require().NoError(err)
-	suite.Require().Equal(path, dev.Device().Name())
-}
-
 func TestProbe(t *testing.T) {
 	if os.Getuid() != 0 {
 		t.Skip("can't run the test as non-root")