Better handle filesystem optional features. (#66)

Filesystems (e.g. ext4, xfs) sometimes receive new features. When these
features are enabled, anything that loads the filesystem (e.g. kernel,
grub, etc.) must support the new feature or it will refuse to load it.

When formatting a new partition, there are a few considerations for if a
filesystem feature should be enabled:

- Does the version of mkfs support that feature?
- Does the build host kernel support that feature?
- Does the target OS support that feature?

This change ensure that all these considerations are handled correctly
for the ext4 and xfs filesystem types.

toolkit/tools/imagegen/diskutils/diskutils.go

@@ -20,21 +20,11 @@ import (
 	"github.com/microsoft/azurelinux/toolkit/tools/internal/logger"
 	"github.com/microsoft/azurelinux/toolkit/tools/internal/retry"
 	"github.com/microsoft/azurelinux/toolkit/tools/internal/shell"
+	"github.com/microsoft/azurelinux/toolkit/tools/internal/targetos"
 	"github.com/sirupsen/logrus"
 )
 
 var (
-	// When calling mkfs, the default options change depending on the host OS you are running on and typically match
-	// what the distro has decided is best for their OS. For example, for ext2/3/4, the defaults are stored in
-	// /etc/mke2fs.conf.
-	// However, when building Azure Linux images, the defaults should be as consistent as possible and should only contain
-	// features that are supported on Azure Linux.
-	DefaultMkfsOptions = map[string][]string{
-		"ext2": {"-b", "4096", "-O", "none,sparse_super,large_file,filetype,resize_inode,dir_index,ext_attr"},
-		"ext3": {"-b", "4096", "-O", "none,sparse_super,large_file,filetype,resize_inode,dir_index,ext_attr,has_journal"},
-		"ext4": {"-b", "4096", "-O", "none,sparse_super,large_file,filetype,resize_inode,dir_index,ext_attr,has_journal,extent,huge_file,flex_bg,metadata_csum,64bit,dir_nlink,extra_isize"},
-	}
-
 	partedVersionRegex = regexp.MustCompile(`^parted \(GNU parted\) (\d+)\.(\d+)`)
 
 	// The default partition name used when the version of `parted` is too old (<3.5).
@@ -433,7 +423,7 @@ func WaitForDevicesToSettle() error {
 }
 
 // CreatePartitions creates partitions on the specified disk according to the disk config
-func CreatePartitions(diskDevPath string, disk configuration.Disk, rootEncryption configuration.RootEncryption,
+func CreatePartitions(targetOs targetos.TargetOs, diskDevPath string, disk configuration.Disk, rootEncryption configuration.RootEncryption,
 	diskKnownToBeEmpty bool,
 ) (partDevPathMap map[string]string, partIDToFsTypeMap map[string]string, encryptedRoot EncryptedRootDevice, err error) {
 	const timeoutInSeconds = "5"
@@ -492,7 +482,7 @@ func CreatePartitions(diskDevPath string, disk configuration.Disk, rootEncryptio
 			return partDevPathMap, partIDToFsTypeMap, encryptedRoot, err
 		}
 
-		partFsType, err := FormatSinglePartition(partDevPath, partition)
+		partFsType, err := formatSinglePartition(targetOs, partDevPath, partition)
 		if err != nil {
 			err = fmt.Errorf("failed to format partition:\n%w", err)
 			return partDevPathMap, partIDToFsTypeMap, encryptedRoot, err
@@ -789,8 +779,8 @@ func setGptPartitionType(partition configuration.Partition, timeoutInSeconds, di
 	return
 }
 
-// FormatSinglePartition formats the given partition to the type specified in the partition configuration
-func FormatSinglePartition(partDevPath string, partition configuration.Partition,
+// formatSinglePartition formats the given partition to the type specified in the partition configuration
+func formatSinglePartition(targetOs targetos.TargetOs, partDevPath string, partition configuration.Partition,
 ) (fsType string, err error) {
 	const (
 		totalAttempts = 5
@@ -804,12 +794,17 @@ func FormatSinglePartition(partDevPath string, partition configuration.Partition
 	// To handle such cases, we can retry the command.
 	switch fsType {
 	case "fat32", "fat16", "vfat", "ext2", "ext3", "ext4", "xfs":
-		mkfsOptions := DefaultMkfsOptions[fsType]
-
 		if fsType == "fat32" || fsType == "fat16" {
 			fsType = "vfat"
 		}
 
+		mkfsOptions, err := getFileSystemOptions(targetOs, fsType)
+		if err != nil {
+			err = fmt.Errorf("failed to get mkfs args for filesystem type (%s) and target os (%s):\n%w", fsType,
+				targetOs, err)
+			return fsType, err
+		}
+
 		mkfsArgs := []string{"-t", fsType}
 		mkfsArgs = append(mkfsArgs, mkfsOptions...)
 		mkfsArgs = append(mkfsArgs, partDevPath)
@@ -825,6 +820,7 @@ func FormatSinglePartition(partDevPath string, partition configuration.Partition
 		}, totalAttempts, retryDuration)
 		if err != nil {
 			err = fmt.Errorf("could not format partition with type %v after %v retries", fsType, totalAttempts)
+			return "", err
 		}
 	case "linux-swap":
 		err = retry.Run(func() error {
@@ -837,6 +833,7 @@ func FormatSinglePartition(partDevPath string, partition configuration.Partition
 		}, totalAttempts, retryDuration)
 		if err != nil {
 			err = fmt.Errorf("could not format partition with type %v after %v retries", fsType, totalAttempts)
+			return "", err
 		}
 
 		_, stderr, err := shell.Execute("swapon", partDevPath)