sgdisk: Run partx after partition changes

The sgdisk tool does not update the kernel partition table with BLKPG in
contrast to other similar tools but only uses BLKRRPART which fails as
soon as one partition of the disk is mounted.
Update the kernel partition table with partx when we know that a
partition of the disk is in use.

docs/release-notes.md

@@ -19,11 +19,13 @@ nav_order: 9
 ### Changes
 
 - Require Go 1.19+
+- The Dracut module now installs partx
 
 ### Bug fixes
 
 - Prevent races with udev after disk editing
 - Don't fail to wipe partition table if it's corrupted
+- Force partition table update after repartitioning, even if one partition is already mounted
 
 
 ## Ignition 2.16.2 (2023-07-12)

dracut/30ignition/module-setup.sh

@@ -33,6 +33,7 @@ install() {
         mkfs.xfs \
         mkswap \
         sgdisk \
+        partx \
         useradd \
         userdel \
         usermod \

internal/distro/distro.go

@@ -37,6 +37,7 @@ var (
 	mdadmCmd     = "mdadm"
 	mountCmd     = "mount"
 	sgdiskCmd    = "sgdisk"
+	partxCmd     = "partx"
 	modprobeCmd  = "modprobe"
 	udevadmCmd   = "udevadm"
 	usermodCmd   = "usermod"
@@ -90,6 +91,7 @@ func GroupdelCmd() string  { return groupdelCmd }
 func MdadmCmd() string     { return mdadmCmd }
 func MountCmd() string     { return mountCmd }
 func SgdiskCmd() string    { return sgdiskCmd }
+func PartxCmd() string     { return partxCmd }
 func ModprobeCmd() string  { return modprobeCmd }
 func UdevadmCmd() string   { return udevadmCmd }
 func UsermodCmd() string   { return usermodCmd }

internal/exec/stages/disks/partitions.go

@@ -24,6 +24,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"regexp"
 	"sort"
@@ -32,6 +33,7 @@ import (
 
 	cutil "github.com/coreos/ignition/v2/config/util"
 	"github.com/coreos/ignition/v2/config/v3_5_experimental/types"
+	"github.com/coreos/ignition/v2/internal/distro"
 	"github.com/coreos/ignition/v2/internal/exec/util"
 	"github.com/coreos/ignition/v2/internal/sgdisk"
 )
@@ -536,6 +538,16 @@ func (s stage) partitionDisk(dev types.Disk, devAlias string) error {
 		return fmt.Errorf("commit failure: %v", err)
 	}
 
+	if len(activeParts) > 0 {
+		// In contrast to similar tools, sgdisk does not trigger the update of the
+		// kernel partition table with BLKPG but only uses BLKRRPART which fails
+		// as soon as one partition of the disk is mounted
+		cmd := exec.Command(distro.PartxCmd(), "-u", "-", blockDevResolved)
+		if _, err := s.Logger.LogCmd(cmd, "triggering partition table reread on %q", devAlias); err != nil {
+			return fmt.Errorf("re-reading partitions failed: %v", err)
+		}
+	}
+
 	// It's best to wait here for the /dev/ABC entries to be
 	// (re)created, not only for other parts of the initramfs but
 	// also because s.waitOnDevices() can still race with udev's