incusd/storage/drivers: Handle 4k sector sizes

internal/server/storage/drivers/driver_common.go

@@ -277,6 +277,26 @@ func (d *common) moveGPTAltHeader(devPath string) error {
 		return nil
 	}
 
+	// Our images and VM drives use a 512 bytes sector size.
+	// If the underlying block device uses a different sector size, we
+	// need to fake the correct size through a loop device so sgdisk can
+	// correctly re-locate the partition tables.
+	if linux.IsBlockdevPath(devPath) {
+		blockSize, err := GetPhysicalBlockSize(devPath)
+		if err != nil {
+			return err
+		}
+
+		if blockSize != 512 {
+			devPath, err = loopDeviceSetupAlign(devPath)
+			if err != nil {
+				return err
+			}
+
+			defer func() { _ = loopDeviceAutoDetach(devPath) }()
+		}
+	}
+
 	_, err = subprocess.RunCommand(path, "--move-second-header", devPath)
 	if err == nil {
 		d.logger.Debug("Moved GPT alternative header to end of disk", logger.Ctx{"dev": devPath})

internal/server/storage/drivers/driver_lvm_utils.go

@@ -9,9 +9,6 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
-	"unsafe"
-
-	"golang.org/x/sys/unix"
 
 	internalInstance "github.com/lxc/incus/v6/internal/instance"
 	"github.com/lxc/incus/v6/internal/linux"
@@ -888,22 +885,3 @@ func (d *lvm) deactivateVolume(vol Volume) (bool, error) {
 
 	return false, nil
 }
-
-func (d *lvm) getBlockSize(path string) (int, error) {
-	// Open the block device.
-	f, err := os.Open(path)
-	if err != nil {
-		return -1, err
-	}
-
-	defer func() { _ = f.Close() }()
-
-	// Query the physical block size.
-	var res int32
-	_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(f.Fd()), unix.BLKPBSZGET, uintptr(unsafe.Pointer(&res)))
-	if errno != 0 {
-		return -1, fmt.Errorf("Failed to BLKPBSZGET: %w", unix.Errno(errno))
-	}
-
-	return int(res), nil
-}

internal/server/storage/drivers/driver_lvm_volumes.go

@@ -70,18 +70,6 @@ func (d *lvm) CreateVolume(vol Volume, filler *VolumeFiller, op *operations.Oper
 				if err != nil {
 					return err
 				}
-
-				// Check the block size for image volumes.
-				if vol.volType == VolumeTypeImage {
-					blockSize, err := d.getBlockSize(devPath)
-					if err != nil {
-						return err
-					}
-
-					if blockSize != 512 {
-						return fmt.Errorf("Underlying storage uses %d bytes sector size when virtual machine images require 512 bytes", blockSize)
-					}
-				}
 			}
 
 			allowUnsafeResize := false

internal/server/storage/drivers/utils.go

@@ -12,6 +12,7 @@ import (
 	"sort"
 	"strings"
 	"time"
+	"unsafe"
 
 	"golang.org/x/sys/unix"
 
@@ -797,6 +798,26 @@ func BlockDiskSizeBytes(blockDiskPath string) (int64, error) {
 	return fi.Size(), nil
 }
 
+// GetPhysicalBlockSize returns the physical block size for the device.
+func GetPhysicalBlockSize(blockDiskPath string) (int, error) {
+	// Open the block device.
+	f, err := os.Open(blockDiskPath)
+	if err != nil {
+		return -1, err
+	}
+
+	defer func() { _ = f.Close() }()
+
+	// Query the physical block size.
+	var res int32
+	_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(f.Fd()), unix.BLKPBSZGET, uintptr(unsafe.Pointer(&res)))
+	if errno != 0 {
+		return -1, fmt.Errorf("Failed to BLKPBSZGET: %w", unix.Errno(errno))
+	}
+
+	return int(res), nil
+}
+
 // OperationLockName returns the storage specific lock name to use with locking package.
 func OperationLockName(operationName string, poolName string, volType VolumeType, contentType ContentType, volName string) string {
 	return fmt.Sprintf("%s/%s/%s/%s/%s", operationName, poolName, volType, contentType, volName)
@@ -841,6 +862,16 @@ func loopDeviceSetup(sourcePath string) (string, error) {
 	return strings.TrimSpace(out), nil
 }
 
+// loopDeviceSetupAlign creates a forced 512-byte aligned loop device.
+func loopDeviceSetupAlign(sourcePath string) (string, error) {
+	out, err := subprocess.RunCommand("losetup", "-b", "512", "--find", "--nooverlap", "--show", sourcePath)
+	if err != nil {
+		return "", err
+	}
+
+	return strings.TrimSpace(out), nil
+}
+
 // loopFileAutoDetach enables auto detach mode for a loop device.
 func loopDeviceAutoDetach(loopDevPath string) error {
 	_, err := subprocess.RunCommand("losetup", "--detach", loopDevPath)