[lvm-devel] [PATCH 1/2] lvmdbusd: Add support for LVM writecache

[Tony Asleson]

Reviewed, tested, and committed upstream.

Thanks Vojtech!

-Tony

On 7/1/20 6:27 AM, Vojtech Trefny wrote:
> ---
>  daemons/lvmdbusd/cmdhandler.py |  9 +++++++
>  daemons/lvmdbusd/lv.py         | 43 ++++++++++++++++++++++++++++++++++
>  test/dbus/lvmdbustest.py       | 30 ++++++++++++++++++++++++
>  3 files changed, 82 insertions(+)
> 
> diff --git a/daemons/lvmdbusd/cmdhandler.py b/daemons/lvmdbusd/cmdhandler.py
> index 7d2f4c4ba..1c15b7888 100644
> --- a/daemons/lvmdbusd/cmdhandler.py
> +++ b/daemons/lvmdbusd/cmdhandler.py
> @@ -453,6 +453,15 @@ def lv_cache_lv(cache_pool_full_name, lv_full_name, cache_options):
>  	return call(cmd)
>  
>  
> +def lv_writecache_lv(cache_lv_full_name, lv_full_name, cache_options):
> +	# lvconvert --type writecache --cachevol VG/CacheLV VG/OriginLV
> +	cmd = ['lvconvert']
> +	cmd.extend(options_to_cli_args(cache_options))
> +	cmd.extend(['-y', '--type', 'writecache', '--cachevol',
> +				cache_lv_full_name, lv_full_name])
> +	return call(cmd)
> +
> +
>  def lv_detach_cache(lv_full_name, detach_options, destroy_cache):
>  	cmd = ['lvconvert']
>  	if destroy_cache:
> diff --git a/daemons/lvmdbusd/lv.py b/daemons/lvmdbusd/lv.py
> index fd46f348b..f21a332a3 100644
> --- a/daemons/lvmdbusd/lv.py
> +++ b/daemons/lvmdbusd/lv.py
> @@ -743,6 +743,49 @@ class Lv(LvCommon):
>  			cb, cbe, return_tuple=False)
>  		cfg.worker_q.put(r)
>  
> +	@staticmethod
> +	def _writecache_lv(lv_uuid, lv_name, lv_object_path, cache_options):
> +		# Make sure we have a dbus object representing it
> +		dbo = LvCommon.validate_dbus_object(lv_uuid, lv_name)
> +
> +		# Make sure we have dbus object representing lv to cache
> +		lv_to_cache = cfg.om.get_object_by_path(lv_object_path)
> +
> +		if lv_to_cache:
> +			fcn = lv_to_cache.lv_full_name()
> +			rc, out, err = cmdhandler.lv_writecache_lv(
> +				dbo.lv_full_name(), fcn, cache_options)
> +			if rc == 0:
> +				# When we cache an LV, the cache pool and the lv that is getting
> +				# cached need to be removed from the object manager and
> +				# re-created as their interfaces have changed!
> +				mt_remove_dbus_objects((dbo, lv_to_cache))
> +				cfg.load()
> +
> +				lv_converted = cfg.om.get_object_path_by_lvm_id(fcn)
> +			else:
> +				raise dbus.exceptions.DBusException(
> +					LV_INTERFACE,
> +					'Exit code %s, stderr = %s' % (str(rc), err))
> +		else:
> +			raise dbus.exceptions.DBusException(
> +				LV_INTERFACE, 'LV to cache with object path %s not present!' %
> +				lv_object_path)
> +		return lv_converted
> +
> +	@dbus.service.method(
> +		dbus_interface=LV_INTERFACE,
> +		in_signature='oia{sv}',
> +		out_signature='(oo)',
> +		async_callbacks=('cb', 'cbe'))
> +	def WriteCacheLv(self, lv_object, tmo, cache_options, cb, cbe):
> +		r = RequestEntry(
> +			tmo, Lv._writecache_lv,
> +			(self.Uuid, self.lvm_id, lv_object,
> +			cache_options), cb, cbe)
> +		cfg.worker_q.put(r)
> +
> +
>  # noinspection PyPep8Naming
>  @utils.dbus_property(VDO_POOL_INTERFACE, 'OperatingMode', 's')
>  @utils.dbus_property(VDO_POOL_INTERFACE, 'CompressionState', 's')
> diff --git a/test/dbus/lvmdbustest.py b/test/dbus/lvmdbustest.py
> index 8753e65d0..efa1afb26 100755
> --- a/test/dbus/lvmdbustest.py
> +++ b/test/dbus/lvmdbustest.py
> @@ -1558,6 +1558,36 @@ class TestDbusService(unittest.TestCase):
>  			cached_lv.Lv.Rename(dbus.String(new_name), dbus.Int32(g_tmo), EOD))
>  		verify_cache_lv_count()
>  
> +	def test_writecache_lv(self):
> +		vg = self._vg_create().Vg
> +		data_lv = self._create_lv(size=mib(16), vg=vg)
> +		cache_lv = self._create_lv(size=mib(16), vg=vg)
> +
> +		# both LVs need to be inactive
> +		self.handle_return(data_lv.Lv.Deactivate(
> +			dbus.UInt64(0), dbus.Int32(g_tmo), EOD))
> +		data_lv.update()
> +		self.handle_return(cache_lv.Lv.Deactivate(
> +			dbus.UInt64(0), dbus.Int32(g_tmo), EOD))
> +		cache_lv.update()
> +
> +		cached_lv_path = self.handle_return(
> +			cache_lv.Lv.WriteCacheLv(
> +				dbus.ObjectPath(data_lv.object_path),
> +				dbus.Int32(g_tmo),
> +				EOD))
> +
> +		intf = (LV_COMMON_INT, LV_INT, CACHE_LV_INT)
> +		cached_lv = ClientProxy(self.bus, cached_lv_path, interfaces=intf)
> +		self.assertEqual(cached_lv.LvCommon.SegType, ["writecache"])
> +
> +		uncached_lv_path = self.handle_return(
> +				cached_lv.CachedLv.DetachCachePool(
> +					dbus.Boolean(True),
> +					dbus.Int32(g_tmo),
> +					EOD))
> +		self.assertTrue('/com/redhat/lvmdbus1/Lv' in uncached_lv_path)
> +
>  	def test_vg_change(self):
>  		vg_proxy = self._vg_create()
>  
>