From a0c55b917bb4ecabd75cbdb3224187a09c427500 Mon Sep 17 00:00:00 2001
From: Arne Wiebalck <Arne.Wiebalck@cern.ch>
Date: Mon, 4 Oct 2021 16:57:56 +0200
Subject: [PATCH] Software RAID: Call udev_settle before creation

This patch fixes a race during software RAID creation:
we create the partition with parted, the kernel then
notifies udev, but we need to wait for udevd to create
the device files before calling mdadm to create the
md device.

Credits to jcosmao for finding this.

Change-Id: I642f28acc351cf50263e37dfbc8468bf59de2cc5
(cherry picked from commit 9d707e9f4bab40109b7e29df2136e86d65325ea3)
---
 ironic_python_agent/hardware.py                            | 7 +++++++
 .../fix-nvme-software-raid-race-2e0e104de9611228.yaml      | 7 +++++++
 2 files changed, 14 insertions(+)
 create mode 100644 releasenotes/notes/fix-nvme-software-raid-race-2e0e104de9611228.yaml

diff --git a/ironic_python_agent/hardware.py b/ironic_python_agent/hardware.py
index fb7437442..3f3e4e0c8 100644
--- a/ironic_python_agent/hardware.py
+++ b/ironic_python_agent/hardware.py
@@ -2152,6 +2152,13 @@ class GenericHardwareManager(HardwareManager):
                     utils.execute('parted', device, '-s', '-a',
                                   'optimal', '--', 'mkpart', 'primary',
                                   start_str, end_str)
+
+                    # Parted/udev partition creation is asynchronous.
+                    # Wait for udev events to be processed before going to
+                    # next step. This avoids getting errors at mdadm
+                    # create because a device is not ready yet.
+                    _udev_settle()
+
                     # Necessary, if we want to avoid hitting
                     # an error when creating the mdadm array below
                     # 'mdadm: cannot open /dev/nvme1n1p1: No such file
diff --git a/releasenotes/notes/fix-nvme-software-raid-race-2e0e104de9611228.yaml b/releasenotes/notes/fix-nvme-software-raid-race-2e0e104de9611228.yaml
new file mode 100644
index 000000000..1a6bfa57a
--- /dev/null
+++ b/releasenotes/notes/fix-nvme-software-raid-race-2e0e104de9611228.yaml
@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixes a race on software RAID creation: since the creation of
+    partitions is asynchronous, we need to wait for all udev events
+    to be processed before we can use the partitions to create an
+    md device.