From 880735906665f501187ab7066502ca38b23df961 Mon Sep 17 00:00:00 2001
From: Ian Kelling <iank@fsf.org>
Date: Wed, 14 May 2025 23:23:32 -0400
Subject: [PATCH] add option for empty disk name to replace original root
 filesystem

---
 .../files/simple/usr/local/bin/create-vm      | 21 ++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/roles/kvmhost/files/simple/usr/local/bin/create-vm b/roles/kvmhost/files/simple/usr/local/bin/create-vm
index 25a7612..6511a55 100755
--- a/roles/kvmhost/files/simple/usr/local/bin/create-vm
+++ b/roles/kvmhost/files/simple/usr/local/bin/create-vm
@@ -82,7 +82,7 @@ usage() {
   cat <<EOF
 Usage: $0 [OPTONS] DISK_SIZE(MB) RAM_SIZE(MB) CPU_COUNT DISTRO_RELEASE_CODENAME FQDN
 or
-$0 [OPTONS] -d DISK_SIZE(MB) DISK_NAME/MOUNT_POINT FQDN
+$0 [OPTONS] -d DISK_SIZE(MB) [DISK_NAME]/MOUNT_POINT FQDN
 or
 $0 -l
 
@@ -108,11 +108,16 @@ WARNING: If this script fails or is inturupted, it will output instructions
 to undo what it has done. Be sure to read the output!
 
 
--d --disk    : Create and add an extra disk to an
-                                 existing VM.  DISK_NAME could be
-                                 something like "data". If MOUNT_POINT is
-                                 "none", we will add it as a swap partition.
-                          This is not yet supported outside ceph.
+-d --disk : Create and add an extra disk to an existing VM.  DISK_NAME
+                       is a suffix for /dev/mapper device names. It
+                       could be something like "data". It must be
+                       something unused, you can search for the vm name
+                       in lsblk to find names already in use. An empty
+                       DISK_NAME is used for the root filesystem when a
+                       new vm is created and can only be specified if
+                       that filesystem no longer exists. If MOUNT_POINT
+                       is "none", we will add it as a swap partition.
+                       This is not yet supported outside ceph.
 
 -i --import : For importing/migrating existing vm: creates the vm with a
                            mostly empty disk. Then you can mount the
@@ -1392,7 +1397,9 @@ while true; do
 done
 if $add_disk; then
   read -r new_disk_mb disk_arg host <<<"$@"
-  disk_name_suf=-${disk_arg%%/*}
+  if [[ $disk_arg != /* ]]; then
+    disk_name_suf=-${disk_arg%%/*}
+  fi
   disk_mountpoint=/${disk_arg#*/}
 else
   read -r new_disk_mb ram cpus release host <<<"$@"
-- 
2.25.1