disk: ensure minimum size for filesystems

This commit fixes #2347 by ensuring that a minimum
size of 1GB is set for all file systems. The only
exception to this is the `/usr` which is set to 2GB,
since this was the only mountpoint that was previously
being checked.

internal/disk/partition_table.go

@@ -21,7 +21,7 @@ type PartitionTable struct {
 func NewPartitionTable(basePT *PartitionTable, mountpoints []blueprint.FilesystemCustomization, imageSize uint64, rng *rand.Rand) (*PartitionTable, error) {
 	newPT := basePT.Clone().(*PartitionTable)
 	for _, mnt := range mountpoints {
-		size := newPT.AlignUp(mnt.MinSize)
+		size := newPT.AlignUp(clampFSSize(mnt.Mountpoint, mnt.MinSize))
 		if path := entityPath(newPT, mnt.Mountpoint); len(path) != 0 {
 			resizeEntityBranch(path, size)
 		} else {
@@ -419,6 +419,21 @@ func (pt *PartitionTable) FindMountable(mountpoint string) Mountable {
 	return path[0].(Mountable)
 }
 
+func clampFSSize(mountpoint string, size uint64) uint64 {
+	// set a minimum size of 1GB for all mountpoints
+	var minSize uint64 = 1073741824
+	if mountpoint == "/usr" {
+		// set a minimum size of 2GB for `/usr` mountpoint
+		// since this is current behaviour and the minimum
+		// required to create a bootable image
+		minSize = 2147483648
+	}
+	if minSize > size {
+		return minSize
+	}
+	return size
+}
+
 func resizeEntityBranch(path []Entity, size uint64) {
 	if len(path) == 0 {
 		return

internal/distro/rhel85/distro.go

@@ -466,9 +466,6 @@ func (t *imageType) checkOptions(customizations *blueprint.Customizations, optio
 
 	invalidMountpoints := []string{}
 	for _, m := range mountpoints {
-		if m.Mountpoint == "/usr" && m.MinSize < 2147483648 {
-			m.MinSize = 2147483648
-		}
 		if !isMountpointAllowed(m.Mountpoint) {
 			invalidMountpoints = append(invalidMountpoints, m.Mountpoint)
 		}

internal/distro/rhel86/distro.go

@@ -549,9 +549,6 @@ func (t *imageType) checkOptions(customizations *blueprint.Customizations, optio
 
 	invalidMountpoints := []string{}
 	for _, m := range mountpoints {
-		if m.Mountpoint == "/usr" && m.MinSize < 2147483648 {
-			m.MinSize = 2147483648
-		}
 		if !isMountpointAllowed(m.Mountpoint) {
 			invalidMountpoints = append(invalidMountpoints, m.Mountpoint)
 		}

internal/distro/rhel90/distro.go

@@ -537,9 +537,6 @@ func (t *imageType) checkOptions(customizations *blueprint.Customizations, optio
 
 	invalidMountpoints := []string{}
 	for _, m := range mountpoints {
-		if m.Mountpoint == "/usr" && m.MinSize < 2147483648 {
-			m.MinSize = 2147483648
-		}
 		if !isMountpointAllowed(m.Mountpoint) {
 			invalidMountpoints = append(invalidMountpoints, m.Mountpoint)
 		}

internal/distro/rhel90beta/distro.go

@@ -492,9 +492,6 @@ func (t *imageType) checkOptions(customizations *blueprint.Customizations, optio
 
 	invalidMountpoints := []string{}
 	for _, m := range mountpoints {
-		if m.Mountpoint == "/usr" && m.MinSize < 2147483648 {
-			m.MinSize = 2147483648
-		}
 		if !isMountpointAllowed(m.Mountpoint) {
 			invalidMountpoints = append(invalidMountpoints, m.Mountpoint)
 		}