flatcar · chewi · Jun 8, 2026
@@ -0,0 +1 @@
+- Fixed using Ignition to create new partitions with number 0 to get the next available slot. ([ignition#2234](https://github.com/coreos/ignition/pull/2234))
@@ -0,0 +1,128 @@
+From 22c97cdf614e3db9b2d059dd7758ddf7dd5a282e Mon Sep 17 00:00:00 2001
+From: James Le Cuirot <jlecuirot@microsoft.com>
+Date: Tue, 2 Jun 2026 15:12:37 +0100
+Subject: [PATCH 19/20] stages/disks: Fix giving partition number 0 to get the
+ next available
+
+This was broken since partx was used in commit c2cc56cd. Passing 0 to
+partx causes it to try and add all the partitions, which will almost
+always fail because the kernel will usually already know about at least
+some of them.
+
+This changes getRealStartAndSize() to also determine and return the
+resulting partition numbers so that subsequent operations use these
+instead of 0.
+
+sgdisk does support --new=0, but it has no way to report which partition
+number it actually used.
+
+Signed-off-by: James Le Cuirot <jlecuirot@microsoft.com>
+--- a/internal/exec/stages/disks/partitions.go
++++ b/internal/exec/stages/disks/partitions.go
+@@ -112,15 +112,6 @@ func partitionMatchesCommon(existing util.PartitionInfo, spec sgdisk.Partition)
+ 	return nil
+ }
+
+-// partitionShouldBeInspected returns if the partition has zeroes that need to be resolved to sectors.
+-func partitionShouldBeInspected(part sgdisk.Partition) bool {
+-	if part.Number == 0 {
+-		return false
+-	}
+-	return (part.StartSector != nil && *part.StartSector == 0) ||
+-		(part.SizeInSectors != nil && *part.SizeInSectors == 0)
+-}
+-
+ func convertMiBToSectors(mib *int, sectorSize int) *int64 {
+ 	if mib != nil {
+ 		v := int64(*mib) * (1024 * 1024 / int64(sectorSize))
+@@ -130,10 +121,17 @@ func convertMiBToSectors(mib *int, sectorSize int) *int64 {
+ 	}
+ }
+
+-// getRealStartAndSize returns a map of partition numbers to a struct that contains what their real start
+-// and end sector should be. It runs sgdisk --pretend to determine what the partitions would look like if
+-// everything specified were to be (re)created.
++// getRealStartAndSize returns a copy of the given partition configuration with the real partition
++// numbers, start sectors, and end sectors filled in. It runs sgdisk --pretend to determine what the
++// partitions would look like if everything specified were to be (re)created.
+ func (s stage) getRealStartAndSize(dev types.Disk, devAlias string, diskInfo util.DiskInfo) ([]sgdisk.Partition, error) {
++	used := map[int]bool{}
++
++	// Determine which partition numbers are already used.
++	for _, part := range diskInfo.Partitions {
++		used[part.Number] = true
++	}
++
+ 	partitions := []sgdisk.Partition{}
+ 	for _, cpart := range dev.Partitions {
+ 		partitions = append(partitions, sgdisk.Partition{
+@@ -156,6 +154,10 @@ func (s stage) getRealStartAndSize(dev types.Disk, devAlias string, diskInfo uti
+ 				part.SizeInSectors = &info.SizeInSectors
+ 			}
+ 		}
++		if part.Number > 0 {
++			// Mark the partition number as used or not.
++			used[part.Number] = partitionShouldExist(part)
++		}
+ 		if partitionShouldExist(part) {
+ 			// Clear the label. sgdisk doesn't escape control characters. This makes parsing easier
+ 			part.Label = nil
+@@ -163,12 +165,25 @@ func (s stage) getRealStartAndSize(dev types.Disk, devAlias string, diskInfo uti
+ 		}
+ 	}
+
+-	// We only care to examine partitions that have start or size 0.
++	free := 1
+ 	partitionsToInspect := []int{}
+-	for _, part := range partitions {
+-		if partitionShouldBeInspected(part) {
+-			op.Info(part.Number)
+-			partitionsToInspect = append(partitionsToInspect, part.Number)
++	for i := range partitions {
++		part := &partitions[i]
++		if partitionShouldExist(*part) {
++			// Find the next free partition number and use it.
++			if part.Number == 0 {
++				for used[free] {
++					free++
++				}
++				part.Number = free
++				free++
++			}
++			// We only care to examine partitions that have start or size 0.
++			if part.StartSector == nil || *part.StartSector == 0 ||
++				part.SizeInSectors == nil || *part.SizeInSectors == 0 {
++				op.Info(part.Number)
++				partitionsToInspect = append(partitionsToInspect, part.Number)
++			}
+ 		}
+ 	}
+
+@@ -182,19 +197,14 @@ func (s stage) getRealStartAndSize(dev types.Disk, devAlias string, diskInfo uti
+ 		return nil, err
+ 	}
+
+-	result := []sgdisk.Partition{}
+-	for _, part := range partitions {
++	for i := range partitions {
++		part := &partitions[i]
+ 		if dims, ok := realDimensions[part.Number]; ok {
+-			if part.StartSector != nil {
+-				part.StartSector = &dims.start
+-			}
+-			if part.SizeInSectors != nil {
+-				part.SizeInSectors = &dims.size
+-			}
++			part.StartSector = &dims.start
++			part.SizeInSectors = &dims.size
+ 		}
+-		result = append(result, part)
+ 	}
+-	return result, nil
++	return partitions, nil
+ }
+
+ type sgdiskOutput struct {
+-- 
+2.54.0
+
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		- Fixed using Ignition to create new partitions with number 0 to get the next available slot. ([ignition#2234](https://github.com/coreos/ignition/pull/2234))