Use `partprobe` to re-read partition table if available (#856)

The blkdev command is fragile re-reading partition tables if a
partition is mounted. This change instead uses the  partprobe if
it is available.

LP: #1920939

1 files changed, 9 insertions, 4 deletions

diff --git a/cloudinit/config/cc_disk_setup.py b/cloudinit/config/cc_disk_setup.py
index d1200694..a582924b 100644
--- a/cloudinit/config/cc_disk_setup.py
+++ b/cloudinit/config/cc_disk_setup.py
@@ -113,6 +113,7 @@ SGDISK_CMD = subp.which("sgdisk")
 LSBLK_CMD = subp.which("lsblk")
 BLKID_CMD = subp.which("blkid")
 BLKDEV_CMD = subp.which("blockdev")
+PARTPROBE_CMD = subp.which("partprobe")
 WIPEFS_CMD = subp.which("wipefs")
 
 LANG_C_ENV = {'LANG': 'C'}
@@ -685,13 +686,17 @@ def get_partition_layout(table_type, size, layout):
 
 def read_parttbl(device):
     """
-    Use partprobe instead of 'udevadm'. Partprobe is the only
-    reliable way to probe the partition table.
+    Use `partprobe` or `blkdev` instead of `udevadm`. `Partprobe` is
+    preferred over `blkdev` since it is more reliably able to probe
+    the partition table.
     """
-    blkdev_cmd = [BLKDEV_CMD, '--rereadpt', device]
+    if PARTPROBE_CMD is not None:
+        probe_cmd = [PARTPROBE_CMD, device]
+    else:
+        probe_cmd = [BLKDEV_CMD, '--rereadpt', device]
     util.udevadm_settle()
     try:
-        subp.subp(blkdev_cmd)
+        subp.subp(probe_cmd)
     except Exception as e:
         util.logexc(LOG, "Failed reading the partition table %s" % e)