sgdisk: Run partprobe after partition changes

The sgdisk tool does not update the kernel partition table in contrast
to other similar tools. Often udev can detect the changes but not always
as experienced when adding a new partition on Flatcar's boot disk.
Instead of implicitly relying on some other component to re-read the
kernel partition table, trigger the re-read with partprobe.

Author: pothos

docs/release-notes.md

@@ -15,10 +15,12 @@ nav_order: 9
 
 ### Changes
 
+- The Dracut module now installs partprobe
 
 ### Bug fixes
 
 - Prevent races with udev after disk editing
+- A partition table re-read fixes corner cases where udev couldn't pick up changes
 
 
 ## Ignition 2.16.2 (2023-07-12)

dracut/30ignition/module-setup.sh

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

internal/distro/distro.go

@@ -37,6 +37,7 @@ var (
 	mdadmCmd     = "mdadm"
 	mountCmd     = "mount"
 	sgdiskCmd    = "sgdisk"
+	partprobeCmd = "partprobe"
 	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 PartprobeCmd() string { return partprobeCmd }
 func ModprobeCmd() string  { return modprobeCmd }
 func UdevadmCmd() string   { return udevadmCmd }
 func UsermodCmd() string   { return usermodCmd }

internal/sgdisk/sgdisk.go

@@ -121,6 +121,11 @@ 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
+	cmd = exec.Command(distro.PartprobeCmd(), op.dev)
+	if _, err := op.logger.LogCmd(cmd, "re-reading of %d deleted partitions and %d created partitions on %q", len(op.deletions), len(op.parts), op.dev); err != nil {
+		return fmt.Errorf("re-reading partitions failed: %v", err)
+	}
 
 	return nil
 }