ceph-disk: partprobe after creating journal partition

At least one user reports that a partprobe is needed after creating the
journal partition.  It is not clear why sgdisk is not doing it, but this
fixes ceph-disk for them, and should be harmless for other users.

Fixes: #5599
Tested-by: lurbs in #ceph
Signed-off-by: Sage Weil <sage@inktank.com>

src/ceph-disk

@@ -850,9 +850,21 @@ def prepare_journal_dev(
                 journal,
                 ],
             )
+
+        # try to make sure the kernel refreshes the table.  note
+        # that if this gets ebusy, we are probably racing with
+        # udev because it already updated it.. ignore failure here.
+        LOG.debug('Calling partprobe on prepared device %s', journal)
+        subprocess.call(
+            args=[
+                'partprobe',
+                journal,
+                ],
+            )
+
+        # wait for udev event queue to clear
         subprocess.call(
             args=[
-                # wait for udev event queue to clear
                 'udevadm',
                 'settle',
                 ],