Add support to resize rootfs if using LVM (#721)

This patch adds support to resize a single partition of a VM if it's using an
LVM underneath. The patch detects if it's LVM if the given block device
is a device mapper by its name (e.g. `/dev/dm-1`) and if it has slave
devices under it on sysfs. After that syspath is updated to the real
block device and growpart will be called to resize it (and automatically
its Physical Volume).

The Volume Group will be updated automatically and a final call to
extend the rootfs to the remaining space available will be made.

Using the same growpart configuration, the user can specify only one
device to be resized when using LVM and growpart, otherwise cloud-init
won't know which one should be resized and will fail.

rhbz: #1810878
LP: #1799953

Signed-off-by: Eduardo Otubo <otubo@redhat.com>
Signed-off-by: Scott Moser <smoser@brickies.net>

1 files changed, 55 insertions, 1 deletions

diff --git a/tests/unittests/test_handler/test_handler_growpart.py b/tests/unittests/test_handler/test_handler_growpart.py
index 7f039b79..cc0a9248 100644
--- a/tests/unittests/test_handler/test_handler_growpart.py
+++ b/tests/unittests/test_handler/test_handler_growpart.py
@@ -172,6 +172,53 @@ class TestResize(unittest.TestCase):
         self.name = "growpart"
         self.log = logging.getLogger("TestResize")
 
+    def test_lvm_resize(self):
+        # LVM resize should work only if a single device is configured. More
+        # than one device should fail.
+        lvm_pass = ["/dev/XXdm-0"]
+        lvm_fail = ["/dev/XXdm-1", "/dev/YYdm-1"]
+        devstat_ret = Bunch(st_mode=25008, st_ino=6078, st_dev=5,
+                            st_nlink=1, st_uid=0, st_gid=6, st_size=0,
+                            st_atime=0, st_mtime=0, st_ctime=0)
+        real_stat = os.stat
+        resize_calls = []
+
+        class myresizer(object):
+            def resize(self, diskdev, partnum, partdev):
+                resize_calls.append((diskdev, partnum, partdev))
+                if partdev == "/dev/XXdm-0":
+                    return (1024, 2048)
+                return (1024, 1024)  # old size, new size
+
+        def mystat(path):
+            if path in lvm_pass or path in lvm_fail:
+                return devstat_ret
+            return real_stat(path)
+
+        try:
+            opinfo = cc_growpart.device_part_info
+            cc_growpart.device_part_info = simple_device_part_info_lvm
+            os.stat = mystat
+
+            resized = cc_growpart.resize_devices(myresizer(), lvm_pass)
+            not_resized = cc_growpart.resize_devices(myresizer(), lvm_fail)
+
+            def find(name, res):
+                for f in res:
+                    if f[0] == name:
+                        return f
+                return None
+
+            self.assertEqual(cc_growpart.RESIZE.CHANGED,
+                             find("/dev/XXdm-0", resized)[1])
+            self.assertEqual(cc_growpart.RESIZE.NOCHANGE,
+                             find("/dev/XXdm-1", not_resized)[1])
+            self.assertEqual(cc_growpart.RESIZE.NOCHANGE,
+                             find("/dev/YYdm-1", not_resized)[1])
+        finally:
+            cc_growpart.device_part_info = opinfo
+            os.stat = real_stat
+
     def test_simple_devices(self):
         # test simple device list
         # this patches out devent2dev, os.stat, and device_part_info
@@ -227,7 +274,14 @@ class TestResize(unittest.TestCase):
             os.stat = real_stat
 
 
-def simple_device_part_info(devpath):
+def simple_device_part_info_lvm(devpath, is_lvm):
+    # simple stupid return (/dev/vda, 1) for /dev/vda
+    ret = re.search("([^0-9]*)([0-9]*)$", devpath)
+    x = (ret.group(1), ret.group(2))
+    return x
+
+
+def simple_device_part_info(devpath, is_lvm):
     # simple stupid return (/dev/vda, 1) for /dev/vda
     ret = re.search("([^0-9]*)([0-9]*)$", devpath)
     x = (ret.group(1), ret.group(2))