zfs-ng: implement volume-create 2/2: Volume.create

Note that if Volume.set were not implemented yet (or indeed cannot
complete and returns an error), we face xapi-project/xen-api#5530: if
the Volume.set call fails (to add the vdi-type=user custom-key
record), then the VDI object is not created (though, as this happens
after Volume.create, the zvol and DB entries were indeed created and
there suppression was not requested by SMAPI after the error).  But
since all the VDI information that count are here, "xe sr-scan" will
bring those VDI to life (after implementation of SR.ls).

Originally-by: Matias Ezequiel Vara Larsen <[email protected]>
Signed-off-by: Yann Dirson <[email protected]>

plugins/volume/org.xen.xapi.storage.zfs-ng/plugin.py

@@ -20,6 +20,7 @@ def query(self, dbg):
             "version": "3.0",
             "required_api_version": "5.0",
             "features": [
+                "VDI_CREATE",
             ],
             "configuration": {},
             "required_cluster_stack": []}

plugins/volume/org.xen.xapi.storage.zfs-ng/volume.py

@@ -16,18 +16,55 @@
 from xapi.storage.libs.libcow.volume_implementation import Implementation as \
     DefaultImplementation
 
+import zfsutils
+
 @util.decorate_all_routines(util.log_exceptions_in_function)
 class Implementation(DefaultImplementation):
     "Volume driver to provide volumes from zvol's"
 
+    def create(self, dbg, sr, name, description, size, sharable):
+        meta = util.get_sr_metadata(dbg, 'file://' + sr)
+        pool_name = meta["zpool"]
+
+        with VolumeContext(self.callbacks, sr, 'w') as opq:
+            # FIXME how should we choose image format?
+            image_type = ImageFormat.IMAGE_RAW
+            image_format = ImageFormat.get_format(image_type)
+            vdi_uuid = str(uuid.uuid4())
+
+            with PollLock(opq, 'gl', self.callbacks, 0.5):
+                with self.callbacks.db_context(opq) as db:
+                    volume = db.insert_new_volume(size, image_type)
+                    db.insert_vdi(
+                        name, description, vdi_uuid, volume.id, sharable)
+                    path = zfsutils.zvol_path(pool_name, volume.id)
+                    zfsutils.vol_create(dbg, path, size)
+
+            vdi_uri = self.callbacks.getVolumeUriPrefix(opq) + vdi_uuid
+
+        return {
+            'key': vdi_uuid,    # FIXME check this
+            'uuid': vdi_uuid,
+            'name': name,
+            'description': description,
+            'read_write': True,
+            'virtual_size': size,
+            'physical_utilisation': size, # FIXME - incidently psize gets null in the db
+            'uri': [image_format.uri_prefix + vdi_uri],
+            'sharable': False,
+            'keys': {}
+        }
+
 def call_volume_command():
     """Parse the arguments and call the required command"""
     log.log_call_argv()
     fsp = importlib.import_module("zfs-ng")
     cmd = xapi.storage.api.v5.volume.Volume_commandline(
         Implementation(fsp.Callbacks()))
     base = os.path.basename(sys.argv[0])
-    if base == "Volume.set":
+    if base == "Volume.create":
+        cmd.create()
+    elif base == "Volume.set":
         cmd.set()
     elif base == "Volume.unset":
         cmd.unset()

plugins/volume/org.xen.xapi.storage.zfs-ng/zfs-ng.py

@@ -3,3 +3,6 @@
 
 class Callbacks(xapi.storage.libs.libcow.callbacks.Callbacks):
     "ZFS-ng callbacks"
+
+    def getVolumeUriPrefix(self, opq):
+        return "zfs-ng/" + opq + "|"

plugins/volume/org.xen.xapi.storage.zfs-ng/zfsutils.py

@@ -4,6 +4,11 @@
 
 MOUNT_ROOT = '/var/run/sr-mount'
 
+def zvol_path(pool_name, vol_id):
+    return "{}/{}".format(pool_name, vol_id)
+
+###
+
 def pool_mountpoint(dbg, pool_name):
     cmd = "zfs get mountpoint -H -o value".split() + [ pool_name ]
     return call(dbg, cmd).strip()
@@ -27,3 +32,9 @@ def pool_get_free_space(dbg, sr_path):
     # size is returned in bytes
     cmd = "zpool get -Hp -o value free".split() + [ sr_path ]
     return int(call(dbg, cmd))
+
+def vol_create(dbg, zvol_path, size_mib):
+    cmd = ("zfs create".split() + [zvol_path]
+           + ['-V', str(size_mib)]
+           )
+    call(dbg, cmd)