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.

Author: pothos

docs/release-notes.md

@@ -15,10 +15,12 @@ nav_order: 9
 
 ### Changes
 
+- The Dracut module now installs partx
 
 ### Bug fixes
 
 - Prevent races with udev after disk editing
+- 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/sgdisk/sgdisk.go

@@ -121,6 +121,13 @@ func (op *Operation) Commit() error {
 	if _, err := op.logger.LogCmd(cmd, "deleting %d partitions and creating %d partitions on %q", len(op.deletions), len(op.parts), op.dev); err != nil {
 		return fmt.Errorf("create partitions failed: %v", err)
 	}
+	// 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", "-", op.dev)
+	if _, err := op.logger.LogCmd(cmd, "triggering partition table reread on %q", op.dev); err != nil {
+		return fmt.Errorf("re-reading partitions failed: %v", err)
+	}
 
 	return nil
 }