machine: Refactor disk resize code

Add `getrootPartition` and `runGrowpart` helper which is used in
follow-up commit.

Author: praveenkumar

pkg/crc/machine/start.go

@@ -15,7 +15,7 @@ import (
 	"github.com/crc-org/crc/pkg/crc/cluster"
 	"github.com/crc-org/crc/pkg/crc/constants"
 	crcerrors "github.com/crc-org/crc/pkg/crc/errors"
-	"github.com/crc-org/crc/pkg/crc/logging"
+	logging "github.com/crc-org/crc/pkg/crc/logging"
 	"github.com/crc-org/crc/pkg/crc/machine/bundle"
 	"github.com/crc-org/crc/pkg/crc/machine/config"
 	"github.com/crc-org/crc/pkg/crc/machine/state"
@@ -118,14 +118,39 @@ func growRootFileSystem(sshRunner *crcssh.Runner, preset crcPreset.Preset) error
 	}
 	// With 4.7, this is quite a manual process until https://github.com/openshift/installer/pull/4746 gets fixed
 	// See https://github.com/crc-org/crc/issues/2104 for details
-	rootPart, _, err := sshRunner.Run("realpath", "/dev/disk/by-label/root")
+	rootPart, err := getrootPartition(sshRunner, "/dev/disk/by-label/root")
 	if err != nil {
 		return err
 	}
+
+	if err := runGrowpart(sshRunner, rootPart); err != nil {
+		return err
+	}
+
+	logging.Infof("Resizing %s filesystem", rootPart)
+	if _, _, err := sshRunner.RunPrivileged("Remounting /sysroot read/write", "mount -o remount,rw /sysroot"); err != nil {
+		return err
+	}
+	if _, _, err = sshRunner.RunPrivileged(fmt.Sprintf("Growing %s filesystem", rootPart), "xfs_growfs", rootPart); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func getrootPartition(sshRunner *crcssh.Runner, label string) (string, error) {
+	rootPart, _, err := sshRunner.Run("realpath", label)
+	if err != nil {
+		return "", err
+	}
 	rootPart = strings.TrimSpace(rootPart)
 	if !strings.HasPrefix(rootPart, "/dev/vda") && !strings.HasPrefix(rootPart, "/dev/sda") {
-		return fmt.Errorf("Unexpected root device: %s", rootPart)
+		return "", fmt.Errorf("Unexpected root device: %s", rootPart)
 	}
+	return rootPart, nil
+}
+
+func runGrowpart(sshRunner *crcssh.Runner, rootPart string) error {
 	// with '/dev/[sv]da4' as input, run 'growpart /dev/[sv]da 4'
 	if _, _, err := sshRunner.RunPrivileged(fmt.Sprintf("Growing %s partition", rootPart), "/usr/bin/growpart", rootPart[:len("/dev/.da")], rootPart[len(rootPart)-1:]); err != nil {
 		var exitErr *ssh.ExitError
@@ -135,19 +160,8 @@ func growRootFileSystem(sshRunner *crcssh.Runner, preset crcPreset.Preset) error
 		if exitErr.ExitStatus() != 1 {
 			return err
 		}
-
 		logging.Debugf("No free space after %s, nothing to do", rootPart)
-		return nil
 	}
-
-	logging.Infof("Resizing %s filesystem", rootPart)
-	if _, _, err := sshRunner.RunPrivileged("Remounting /sysroot read/write", "mount -o remount,rw /sysroot"); err != nil {
-		return err
-	}
-	if _, _, err = sshRunner.RunPrivileged(fmt.Sprintf("Growing %s filesystem", rootPart), "xfs_growfs", rootPart); err != nil {
-		return err
-	}
-
 	return nil
 }