Deprecate the Linux SMBFS driver

We're marking the Linux SMBFS driver as unsupported, completely
removing it during the next release.

We've decided to deprecate it mostly because of its limitations
and lack of demand, unlike the Windows SMB driver which is largely
adopted in Hyper-V deployments.

Our CI will continue to send reports for this driver until it's
completely removed.

DocImpact

Change-Id: I1da58e36fc29a4dfee58454cf123543adbc6cac4

cinder/volume/drivers/smbfs.py

@@ -102,6 +102,8 @@ def update_allocation_data(delete=False):
 class SmbfsDriver(remotefs_drv.RemoteFSSnapDriver):
     """SMBFS based cinder volume driver."""
 
+    SUPPORTED = False
+
     driver_volume_type = 'smbfs'
     driver_prefix = 'smbfs'
     volume_backend_name = 'Generic_SMBFS'

cinder/volume/drivers/windows/smbfs.py

@@ -45,6 +45,10 @@ CONF.set_default('smbfs_default_volume_format', 'vhd')
 
 @interface.volumedriver
 class WindowsSmbfsDriver(smbfs.SmbfsDriver):
+    # NOTE(lpetrut): This driver is currently inhering the Linux SMBFS driver,
+    # which is being deprecated. This dependency will be removed along with
+    # the Linux SMBFS driver during Pike.
+    SUPPORTED = True
     VERSION = VERSION
 
     # ThirdPartySystems wiki page

releasenotes/notes/deprecate-cinder-linux-smb-driver-4aec58f15a963c54.yaml

@@ -0,0 +1,6 @@
+---
+deprecations:
+  - |
+    The Cinder Linux SMBFS driver is now deprecated and will be removed
+    during the following release. Deployers are encouraged to use the
+    Windows SMBFS driver instead.