Fix device mapper partitioning

When run ignition on a device mapper, ie, multipath, it fails because
the function blockDevHeld returns true as the block device
contains holders. A block device with holders do not necessary means
the block device is in use (like mounted).
The function blockDevInUse should look for mounted devices only.

Signed-off-by: Tiago Bueno <[email protected]>

Author: tlbueno

docs/release-notes.md

@@ -28,6 +28,7 @@ nav_order: 9
 ### Bug fixes
 
 - Fix fetch-offline for Oracle Cloud Infrastructure
+- Fix device mapper partitioning ([#2128](https://github.com/coreos/ignition/issues/2128))
 
 ## Ignition 2.22.0 (2025-07-08)
 Starting with this release, ignition-validate binaries are signed with the

internal/exec/stages/disks/partitions.go

@@ -323,18 +323,6 @@ func (p PartitionList) Swap(i, j int) {
 	p[i], p[j] = p[j], p[i]
 }
 
-// Expects a /dev/xyz path
-func blockDevHeld(blockDevResolved string) (bool, error) {
-	_, blockDevNode := filepath.Split(blockDevResolved)
-
-	holdersDir := fmt.Sprintf("/sys/class/block/%s/holders/", blockDevNode)
-	entries, err := os.ReadDir(holdersDir)
-	if err != nil {
-		return false, fmt.Errorf("failed to retrieve holders of %q: %v", blockDevResolved, err)
-	}
-	return len(entries) > 0, nil
-}
-
 // Expects a /dev/xyz path
 func blockDevMounted(blockDevResolved string) (bool, error) {
 	mounts, err := os.Open("/proc/mounts")
@@ -383,16 +371,10 @@ func blockDevPartitions(blockDevResolved string) ([]string, error) {
 // Expects a /dev/xyz path
 func blockDevInUse(blockDevResolved string, skipPartitionCheck bool) (bool, []string, error) {
 	// Note: This ignores swap and LVM usage
-	inUse := false
-	held, err := blockDevHeld(blockDevResolved)
-	if err != nil {
-		return false, nil, fmt.Errorf("failed to check if %q is held: %v", blockDevResolved, err)
-	}
-	mounted, err := blockDevMounted(blockDevResolved)
+	inUse, err := blockDevMounted(blockDevResolved)
 	if err != nil {
 		return false, nil, fmt.Errorf("failed to check if %q is mounted: %v", blockDevResolved, err)
 	}
-	inUse = held || mounted
 	if skipPartitionCheck {
 		return inUse, nil, nil
 	}