support resizing partition and rootfs on system booted without initramfs.

When booted without an initramfs, the root device will be /dev/root, not a
named device. There is partial support for this when resizing filesystems,
but not for growing partitions, without which it doesn't do much good. Move
the /dev/root resolution code to util.py and use it from cc_growpart.py.

Also, booting without an initramfs only works with a root= argument that's
either a kernel device name (which is unstable) or a partition UUID. Handle
the case of root=PARTUUID=value, not just LABEL and UUID.

LP: #1677376

3 files changed, 40 insertions, 21 deletions

diff --git a/cloudinit/config/cc_growpart.py b/cloudinit/config/cc_growpart.py
index 832bb3fd..089693e8 100644
--- a/cloudinit/config/cc_growpart.py
+++ b/cloudinit/config/cc_growpart.py
@@ -247,7 +247,16 @@ def devent2dev(devent):
         result = util.get_mount_info(devent)
         if not result:
             raise ValueError("Could not determine device of '%s' % dev_ent")
-        return result[0]
+        dev = result[0]
+
+    container = util.is_container()
+
+    # Ensure the path is a block device.
+    if (dev == "/dev/root" and not os.path.exists(dev) and not container):
+        dev = util.rootdev_from_cmdline(util.get_cmdline())
+        if dev is None:
+            raise ValueError("Unable to find device '/dev/root'")
+    return dev
 
 
 def resize_devices(resizer, devices):
diff --git a/cloudinit/config/cc_resizefs.py b/cloudinit/config/cc_resizefs.py
index e028abf4..60e3ab53 100644
--- a/cloudinit/config/cc_resizefs.py
+++ b/cloudinit/config/cc_resizefs.py
@@ -71,25 +71,6 @@ RESIZE_FS_PREFIXES_CMDS = [
 NOBLOCK = "noblock"
 
 
-def rootdev_from_cmdline(cmdline):
-    found = None
-    for tok in cmdline.split():
-        if tok.startswith("root="):
-            found = tok[5:]
-            break
-    if found is None:
-        return None
-
-    if found.startswith("/dev/"):
-        return found
-    if found.startswith("LABEL="):
-        return "/dev/disk/by-label/" + found[len("LABEL="):]
-    if found.startswith("UUID="):
-        return "/dev/disk/by-uuid/" + found[len("UUID="):]
-
-    return "/dev/" + found
-
-
 def handle(name, cfg, _cloud, log, args):
     if len(args) != 0:
         resize_root = args[0]
@@ -121,7 +102,7 @@ def handle(name, cfg, _cloud, log, args):
     # Ensure the path is a block device.
     if (devpth == "/dev/root" and not os.path.exists(devpth) and
             not container):
-        devpth = rootdev_from_cmdline(util.get_cmdline())
+        devpth = util.rootdev_from_cmdline(util.get_cmdline())
         if devpth is None:
             log.warn("Unable to find device '/dev/root'")
             return
diff --git a/cloudinit/util.py b/cloudinit/util.py
index 33019579..17abdf81 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -2382,4 +2382,33 @@ def indent(text, prefix):
     return ''.join(lines)
 
 
+def rootdev_from_cmdline(cmdline):
+    found = None
+    for tok in cmdline.split():
+        if tok.startswith("root="):
+            found = tok[5:]
+            break
+    if found is None:
+        return None
+
+    if found.startswith("/dev/"):
+        return found
+    if found.startswith("LABEL="):
+        return "/dev/disk/by-label/" + found[len("LABEL="):]
+    if found.startswith("UUID="):
+        return "/dev/disk/by-uuid/" + found[len("UUID="):]
+    if found.startswith("PARTUUID="):
+        disks_path = "/dev/disk/by-partuuid/" + found[len("PARTUUID="):]
+        if os.path.exists(disks_path):
+            return disks_path
+        results = find_devs_with(found)
+        if results:
+            return results[0]
+        # we know this doesn't exist, but for consistency return the path as
+        # it /would/ exist
+        return disks_path
+
+    return "/dev/" + found
+
+
 # vi: ts=4 expandtab