Merge pull request #727 from arutk/pyvolume

pyocf: composite volume API and initial tests

inc/ocf_composite_volume.h

@@ -16,6 +16,8 @@
 #include "ocf_err.h"
 #include "ocf_volume.h"
 
+#define OCF_VOLUME_TYPE_COMPOSITE 10
+
 /**
  * @brief handle to object designating composite volume
  */

src/ocf_composite_volume.c

@@ -152,6 +152,11 @@ static void ocf_composite_volume_on_deinit(ocf_volume_t cvolume)
 	struct ocf_composite_volume *composite = ocf_volume_get_priv(cvolume);
 	int i;
 
+	/* priv can be NULL if this volume had been moved from. In this case
+	 * it's the owner responsibility to deinit member volumes. */
+	if (!composite)
+		return;
+
 	for (i = 0; i < composite->members_cnt; i++)
 		ocf_volume_deinit(&composite->member[i].volume);
 }
@@ -282,7 +287,7 @@ static void *ocf_composite_io_allocator_new(ocf_io_allocator_t allocator,
 		member_addr = cur_addr - (i > 0 ? composite->end_addr[i-1] : 0);
 		member_bytes =
 			OCF_MIN(cur_addr + cur_bytes, composite->end_addr[i])
-			- member_addr;
+			- cur_addr;
 
 		cio->member_io[i] = ocf_io_new(&composite->member[i].volume, queue,
 				member_addr, member_bytes, dir, 0, 0);

src/ocf_ctx_priv.h

@@ -8,6 +8,7 @@
 
 #include "ocf_env.h"
 #include "ocf/ocf_ctx.h"
+#include "ocf/ocf_composite_volume.h"
 #include "ocf_logger_priv.h"
 #include "ocf_volume_priv.h"
 
@@ -19,7 +20,11 @@
 
 #define OCF_VOLUME_TYPE_CORE (OCF_VOLUME_TYPE_MAX_USER + 0)
 #define OCF_VOLUME_TYPE_CACHE (OCF_VOLUME_TYPE_MAX_USER + 1)
-#define OCF_VOLUME_TYPE_COMPOSITE (OCF_VOLUME_TYPE_MAX_USER + 2)
+#define OCF_VOLUME_TYPE_COMPOSITE_PLACEHOLDER (OCF_VOLUME_TYPE_MAX_USER + 2)
+
+#if OCF_VOLUME_TYPE_COMPOSITE_PLACEHOLDER != OCF_VOLUME_TYPE_COMPOSITE
+#error "composite volume id mismatch"
+#endif
 
 /**
  * @brief OCF main control structure

src/ocf_volume.c

@@ -327,8 +327,10 @@ int ocf_volume_open(ocf_volume_t volume, void *volume_params)
 {
 	int ret;
 
+	if (volume->opened)
+		return -OCF_ERR_NOT_OPEN_EXC;
+
 	ENV_BUG_ON(!volume->type->properties->ops.open);
-	ENV_BUG_ON(volume->opened);
 
 	ret = volume->type->properties->ops.open(volume, volume_params);
 	if (ret)
@@ -352,7 +354,9 @@ void ocf_volume_close(ocf_volume_t volume)
 	env_completion cmpl;
 
 	ENV_BUG_ON(!volume->type->properties->ops.close);
-	ENV_BUG_ON(!volume->opened);
+
+	if (!volume->opened)
+		return;
 
 	env_completion_init(&cmpl);
 	ocf_refcnt_freeze(&volume->refcnt);

tests/functional/pyocf/c/helpers/volume_type.c

@@ -0,0 +1,13 @@
+/*
+ * Copyright(c) 2022-2022 Intel Corporation
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "ocf/ocf_composite_volume.h"
+
+int ocf_get_composite_volume_type_id_helper()
+{
+	return OCF_VOLUME_TYPE_COMPOSITE;
+}
+
+

tests/functional/pyocf/helpers.py

@@ -34,3 +34,8 @@ def get_metadata_segment_elem_size(cache, segment):
 def get_metadata_segment_is_flapped(cache, segment):
     lib = OcfLib.getInstance()
     return bool(lib.ocf_get_metadata_segment_is_flapped(cache, segment))
+
+
+def get_composite_volume_type_id():
+    lib = OcfLib.getInstance()
+    return int(lib.ocf_get_composite_volume_type_id_helper())

tests/functional/pyocf/types/cache.py

@@ -299,7 +299,7 @@ class Cache:
             raise OcfError("Failed to detach failover cache device", c.results["error"])
 
     def standby_activate(self, device, open_cores=True):
-        device_cfg = self.generate_device_config(device)
+        device_cfg = self.alloc_device_config(device)
 
         activate_cfg = CacheStandbyActivateConfig(_device=device_cfg, _open_cores=open_cores,)
 
@@ -311,6 +311,8 @@ class Cache:
         c.wait()
         self.write_unlock()
 
+        self.free_device_config(device_cfg)
+
         if c.results["error"]:
             raise OcfError("Failed to activate standby cache", c.results["error"])
 
@@ -499,7 +501,8 @@ class Cache:
         if status:
             raise OcfError("Error adding partition to cache", status)
 
-    def generate_device_config(self, device, perform_test=True):
+    def alloc_device_config(self, device, perform_test=True):
+        if not device.handle:
             uuid = Uuid(
                 _data=cast(create_string_buffer(device.uuid.encode("ascii")), c_char_p),
                 _size=len(device.uuid) + 1,
@@ -512,8 +515,11 @@ class Cache:
                 self.owner.ocf_volume_type[type(device)],
                 byref(uuid)
             )
+
             if result != 0:
                 raise OcfError("Cache volume initialization failed", result)
+        else:
+            volume = device.handle
 
         device_config = CacheDeviceConfig(
             _volume=volume,
@@ -523,13 +529,16 @@ class Cache:
 
         return device_config
 
+    def free_device_config(self, cfg):
+        lib = OcfLib.getInstance().ocf_volume_destroy(cfg._volume)
+
     def attach_device(
         self, device, force=False, perform_test=False, cache_line_size=None, open_cores=False,
     ):
         self.device = device
         self.device_name = device.uuid
 
-        device_config = self.generate_device_config(device, perform_test=perform_test)
+        device_config = self.alloc_device_config(device, perform_test=perform_test)
 
         attach_cfg = CacheAttachConfig(
             _device=device_config,
@@ -548,6 +557,8 @@ class Cache:
 
         self.write_unlock()
 
+        self.free_device_config(device_config)
+
         if c.results["error"]:
             raise OcfError(
                 f"Attaching cache device failed", c.results["error"],
@@ -557,7 +568,7 @@ class Cache:
         self.device = device
         self.device_name = device.uuid
 
-        device_config = self.generate_device_config(device, perform_test=False)
+        device_config = self.alloc_device_config(device, perform_test=False)
 
         attach_cfg = CacheAttachConfig(
             _device=device_config,
@@ -576,6 +587,8 @@ class Cache:
 
         self.write_unlock()
 
+        self.free_device_config(device_config)
+
         if c.results["error"]:
             raise OcfError(
                 f"Attaching to standby cache failed", c.results["error"],
@@ -585,7 +598,7 @@ class Cache:
         self.device = device
         self.device_name = device.uuid
 
-        device_config = self.generate_device_config(device, perform_test=perform_test)
+        device_config = self.alloc_device_config(device, perform_test=perform_test)
 
         attach_cfg = CacheAttachConfig(
             _device=device_config,
@@ -601,6 +614,8 @@ class Cache:
         c.wait()
         self.write_unlock()
 
+        self.free_device_config(device_config)
+
         if c.results["error"]:
             raise OcfError("Loading standby cache device failed", c.results["error"])
 
@@ -622,7 +637,7 @@ class Cache:
         self.device = device
         self.device_name = device.uuid
 
-        device_config = self.generate_device_config(device)
+        device_config = self.alloc_device_config(device)
 
         attach_cfg = CacheAttachConfig(
             _device=device_config,
@@ -638,6 +653,8 @@ class Cache:
         c.wait()
         self.write_unlock()
 
+        self.free_device_config(device_config)
+
         if c.results["error"]:
             raise OcfError("Loading cache device failed", c.results["error"])
 
@@ -759,10 +776,16 @@ class Cache:
         self.cores.remove(core)
 
     def get_front_volume(self):
-        return Volume.get_instance(lib.ocf_cache_get_front_volume(self.cache_handle))
+        return Volume.get_instance(self.get_c_front_volume())
+
+    def get_c_front_volume(self):
+        return lib.ocf_cache_get_front_volume(self.cache_handle)
 
     def get_volume(self):
-        return Volume.get_instance(lib.ocf_cache_get_volume(self.cache_handle))
+        return Volume.get_instance(self.get_c_volume())
+
+    def get_c_volume(self):
+        return lib.ocf_cache_get_volume(self.cache_handle)
 
     def get_conf(self):
         cache_info = CacheInfo()
@@ -971,3 +994,4 @@ lib.ocf_mngt_cache_io_classes_configure.restype = c_int
 lib.ocf_mngt_cache_io_classes_configure.argtypes = [c_void_p, c_void_p]
 lib.ocf_volume_create.restype = c_int
 lib.ocf_volume_create.argtypes = [c_void_p, c_void_p, c_void_p]
+lib.ocf_volume_destroy.argtypes = [c_void_p]

tests/functional/pyocf/types/core.py

@@ -97,10 +97,16 @@ class Core:
         return self.handle
 
     def get_front_volume(self):
-        return Volume.get_instance(lib.ocf_core_get_front_volume(self.handle))
+        return Volume.get_instance(self.get_c_front_volume())
+
+    def get_c_front_volume(self):
+        return lib.ocf_core_get_front_volume(self.handle)
 
     def get_volume(self):
-        return Volume.get_instance(lib.ocf_core_get_volume(self.handle))
+        return Volume.get_instance(self.get_c_volume())
+
+    def get_c_volume(self):
+        return lib.ocf_core_get_volume(self.handle)
 
     def get_default_queue(self):
         return self.cache.get_default_queue()

tests/functional/pyocf/types/ctx.py

@@ -66,7 +66,18 @@ class OcfCtx:
 
         return cls.default()
 
+    def register_internal_volume_type_id(self, volume_type, volume_type_id):
+        if volume_type_id in self.volume_types:
+            raise RuntimeError(f"volume type id {volume_type_id} already used")
+        self.volume_types[volume_type_id] = volume_type
+        volume_type.internal = True
+
     def register_volume_type(self, volume_type):
+        if self.volume_types_count in self.volume_types:
+            raise RuntimeError(
+                f"volume type id slot already used by internal volume "
+                f"{self.volume_types[self.volume_types_count]}"
+            )
         self.volume_types[self.volume_types_count] = volume_type
         volume_type.type_id = self.volume_types_count
 
@@ -79,10 +90,11 @@ class OcfCtx:
             raise OcfError("Volume type registration failed", result)
 
         self.ocf_volume_type[volume_type] = self.lib.ocf_ctx_get_volume_type(
-            self.ctx_handle,
+            self.ctx_handle, volume_type.type_id
-            volume_type.type_id
         )
 
+        volume_type.internal = False
+
         self.volume_types_count += 1
 
     def unregister_volume_type(self, vol_type):
@@ -96,7 +108,7 @@ class OcfCtx:
 
     def cleanup_volume_types(self):
         for k, vol_type in list(self.volume_types.items()):
-            if vol_type:
+            if vol_type and not vol_type.internal:
                 self.unregister_volume_type(vol_type)
 
     def stop_caches(self):

tests/functional/pyocf/types/cvolume.py

@@ -0,0 +1,78 @@
+#
+# Copyright(c) 2022 Intel Corporation
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+from ctypes import (
+    c_int,
+    c_uint32,
+    c_uint64,
+    c_void_p,
+    c_char_p,
+    byref,
+    cast,
+    create_string_buffer,
+)
+
+from ..ocf import OcfLib
+from .ctx import OcfCtx
+from .io import Io, IoDir
+from .queue import Queue
+from .shared import OcfError, Uuid
+from .volume_exp_obj import OcfInternalVolume
+
+
+class CVolume(OcfInternalVolume):
+    def __init__(self, ctx):
+        super().__init__(None)
+        self.ctx = ctx
+        self.lib = ctx.lib
+
+        self.cvol = c_void_p()
+        ret = lib.ocf_composite_volume_create(byref(self.cvol), self.ctx.ctx_handle)
+
+        if ret != 0:
+            raise OcfError("Composite volume creation failed", ret)
+
+        self.handle = self.cvol.value
+
+    def destroy(self):
+        self.lib.ocf_composite_volume_destroy(self.cvol)
+        self.cvol = None
+        self.handle = 0
+
+    def add(self, vol):
+        uuid = Uuid(
+            _data=cast(create_string_buffer(vol.uuid.encode("ascii")), c_char_p),
+            _size=len(vol.uuid) + 1,
+        )
+
+        volume = c_void_p()
+        ocf_vol_type = self.ctx.ocf_volume_type[type(vol)]
+
+        ret = self.lib.ocf_composite_volume_add(self.cvol, ocf_vol_type, byref(uuid), c_void_p())
+
+        if ret != 0:
+            raise OcfError("Failed to add volume to a composite volume", ret)
+
+    def get_c_handle(self):
+        return self.cvol.value
+
+    def do_open(self):
+        ret = self.lib.ocf_volume_open(self.cvol, c_void_p())
+        if ret != 0:
+            raise OcfError("openning composite volume failed", ret)
+
+    def do_close(self):
+        self.lib.ocf_volume_close(self.cvol)
+
+
+lib = OcfLib.getInstance()
+lib.ocf_composite_volume_create.restype = c_int
+lib.ocf_composite_volume_create.argtypes = [c_void_p, c_void_p]
+lib.ocf_composite_volume_destroy.argtypes = [c_void_p]
+lib.ocf_composite_volume_add.argtypes = [c_void_p, c_void_p, c_void_p, c_void_p]
+lib.ocf_composite_volume_add.restype = c_int
+lib.ocf_volume_open.restype = c_int
+lib.ocf_volume_open.argtypes = [c_void_p, c_void_p]
+lib.ocf_volume_close.argtypes = [c_void_p]

tests/functional/pyocf/types/volume.py

@@ -147,13 +147,12 @@ class Volume:
                 print("{}".format(Volume._uuid_))
                 return -1
 
-            return Volume.open(ref, volume)
+            return Volume.s_open(ref, volume)
 
         @VolumeOps.CLOSE
         def _close(ref):
             volume = Volume.get_instance(ref)
-            volume.close()
+            Volume.s_close(volume)
-            volume.opened = False
 
         @VolumeOps.GET_MAX_IO_SIZE
         def _get_max_io_size(ref):
@@ -180,14 +179,29 @@ class Volume:
         return Volume._ops_[cls]
 
     @staticmethod
-    def open(ref, volume):
+    def s_open(ref, volume):
         if volume.opened:
             return -OcfErrorCode.OCF_ERR_NOT_OPEN_EXC
 
         Volume._instances_[ref] = volume
         volume.handle = ref
 
-        return volume.do_open()
+        ret = volume.do_open()
+        if ret == 0:
+            volume.opened = True
+
+        return ret
+
+    @staticmethod
+    def s_close(volume):
+        if not volume.opened:
+            return
+
+        volume.do_close()
+        volume.opened = False
+
+        del Volume._instances_[volume.handle]
+        volume.handle = None
 
     @classmethod
     def get_io_ops(cls):
@@ -253,13 +267,13 @@ class Volume:
         self.reset_stats()
         self.is_online = True
         self.opened = False
+        self.handle = None
 
     def do_open(self):
-        self.opened = True
         return 0
 
-    def close(self):
+    def do_close(self):
-        self.opened = False
+        pass
 
     def get_length(self):
         raise NotImplementedError
@@ -324,7 +338,13 @@ class Volume:
     ):
         lib = OcfLib.getInstance()
         io = lib.ocf_volume_new_io(
-            self.handle, queue.handle, addr, length, direction, io_class, flags
+            self.handle,
+            queue.handle if queue else c_void_p(),
+            addr,
+            length,
+            direction,
+            io_class,
+            flags,
         )
         return Io.from_pointer(io)
 
@@ -518,15 +538,18 @@ class TraceDevice(Volume):
         if submit:
             self.vol.do_submit_flush(io)
 
+    def do_submit_discard(self, io):
+        submit = self._trace(io, TraceDevice.IoType.Discard)
+
+        if submit:
+            self.vol.do_submit_discard(io)
+
     def get_length(self):
         return self.vol.get_length()
 
     def get_max_io_size(self):
         return self.vol.get_max_io_size()
 
-    def do_submit_discard(self, discard):
-        return self.vol.do_submit_discard(discard)
-
     def dump(self, offset=0, size=0, ignore=VOLUME_POISON, **kwargs):
         return self.vol.dump(offset, size, ignore=ignore, **kwargs)
 

tests/functional/pyocf/types/volume_cache.py

@@ -8,11 +8,11 @@ from ctypes import cast, POINTER
 from .cache import Cache
 from .io import Io
 from .io import IoDir
-from .volume_exp_obj import ExpObjVolume
+from .volume_exp_obj import OcfInternalVolume
 from .volume import Volume
 
 
-class CacheVolume(ExpObjVolume):
+class CacheVolume(OcfInternalVolume):
     def __init__(self, cache, open=False, uuid=None):
         super().__init__(cache, uuid)
         self.cache = cache
@@ -20,8 +20,8 @@ class CacheVolume(ExpObjVolume):
         if open:
             self.open()
 
-    def open(self):
+    def get_c_handle(self):
-        return Volume.open(self.lib.ocf_cache_get_front_volume(self.cache.cache_handle), self)
+        return self.cache.get_c_front_volume()
 
     def md5(self):
         out = self.cache.get_conf()

tests/functional/pyocf/types/volume_core.py

@@ -4,12 +4,12 @@
 #
 
 from .core import Core
-from .volume_exp_obj import ExpObjVolume
+from .volume_exp_obj import OcfInternalVolume
 from .io import IoDir
 from .volume import Volume
 
 
-class CoreVolume(ExpObjVolume):
+class CoreVolume(OcfInternalVolume):
     def __init__(self, core, open=False, uuid=None):
         super().__init__(core, uuid)
         self.core = core
@@ -17,8 +17,8 @@ class CoreVolume(ExpObjVolume):
         if open:
             self.open()
 
-    def open(self):
+    def get_c_handle(self):
-        return Volume.open(self.lib.ocf_core_get_front_volume(self.core.handle), self)
+        return self.core.get_c_front_volume()
 
     def md5(self):
         return self._exp_obj_md5(4096)

tests/functional/pyocf/types/volume_exp_obj.py

@@ -14,7 +14,7 @@ from pyocf.types.io import IoDir, Io
 from pyocf.types.shared import OcfCompletion
 
 
-class ExpObjVolume(Volume):
+class OcfInternalVolume(Volume):
     def __init__(self, parent, uuid=None):
         super().__init__(uuid)
         self.parent = parent
@@ -113,6 +113,13 @@ class ExpObjVolume(Volume):
 
         return read_buffer_all.md5()
 
+    def open(self):
+        handle = self.get_c_handle()
+        return Volume.s_open(handle, self)
+
+    def close(self):
+        return Volume.s_close(self)
+
 
 lib = OcfLib.getInstance()
 lib.ocf_volume_get_max_io_size.argtypes = [c_void_p]

tests/functional/tests/conftest.py

@@ -14,7 +14,9 @@ from pyocf.types.volume import RamVolume, ErrorDevice
 from pyocf.types.volume_cache import CacheVolume
 from pyocf.types.volume_core import CoreVolume
 from pyocf.types.volume_replicated import ReplicatedVolume
+from pyocf.types.cvolume import CVolume
 from pyocf.types.ctx import OcfCtx
+from pyocf.helpers import get_composite_volume_type_id
 
 default_registered_volumes = [RamVolume, ErrorDevice, CacheVolume, CoreVolume, ReplicatedVolume]
 
@@ -28,6 +30,7 @@ def pyocf_ctx():
     c = OcfCtx.with_defaults(DefaultLogger(LogLevel.WARN))
     for vol_type in default_registered_volumes:
         c.register_volume_type(vol_type)
+    c.register_internal_volume_type_id(CVolume, get_composite_volume_type_id())
     yield c
     c.exit()
     gc.collect()
@@ -39,6 +42,7 @@ def pyocf_ctx_log_buffer():
     c = OcfCtx.with_defaults(logger)
     for vol_type in default_registered_volumes:
         c.register_volume_type(vol_type)
+    c.register_internal_volume_type_id(CVolume, get_composite_volume_type_id())
     yield logger
     c.exit()
     gc.collect()
@@ -51,6 +55,8 @@ def pyocf_2_ctx():
     for vol_type in default_registered_volumes:
         c1.register_volume_type(vol_type)
         c2.register_volume_type(vol_type)
+    c1.register_internal_volume_type_id(CVolume, get_composite_volume_type_id())
+    c2.register_internal_volume_type_id(CVolume, get_composite_volume_type_id())
     yield [c1, c2]
     c1.exit()
     c2.exit()

tests/functional/tests/failover/test_standby_io.py

@@ -34,10 +34,11 @@ def test_test_standby_io(pyocf_ctx, cacheline_size):
         cache.add_io_queue(f"io-queue-{i}")
 
     cache.standby_attach(cache_vol)
+    cache_vol = CacheVolume(cache, open=True)
 
     r = (
         Rio()
-        .target(cache)
+        .target(cache_vol)
         .njobs(num_jobs)
         .readwrite(ReadWrite.RANDWRITE)
         .size(vol_size)

tests/functional/tests/management/test_composite_volume.py

@@ -4,9 +4,16 @@
 #
 
 import pytest
+from ctypes import c_int
+
+from pyocf.types.volume import RamVolume, ErrorDevice, TraceDevice, IoFlags
+from pyocf.types.cvolume import CVolume
+from pyocf.types.data import Data
+from pyocf.types.io import IoDir
+from pyocf.types.shared import OcfError, OcfCompletion
+from pyocf.utils import Size as S
 
 
-@pytest.mark.skip(reason="not implemented")
 def test_create_composite_volume(pyocf_ctx):
     """
     title: Create composite volume.
@@ -26,10 +33,12 @@ def test_create_composite_volume(pyocf_ctx):
       - composite_volume::creation
       - composite_volume::adding_component_volume
     """
-    pass
+    cvol = CVolume(pyocf_ctx)
+    vol = RamVolume(S.from_MiB(1))
+    cvol.add(vol)
+    cvol.destroy()
 
 
-@pytest.mark.skip(reason="not implemented")
 def test_add_subvolumes_of_different_types(pyocf_ctx):
     """
     title: Add subvolumes of different types.
@@ -49,10 +58,16 @@ def test_add_subvolumes_of_different_types(pyocf_ctx):
     requirements:
       - composite_volume::component_volume_types
     """
-    pass
+    vol1 = RamVolume(S.from_MiB(1))
+    vol2_backend = RamVolume(S.from_MiB(1))
+    vol2 = ErrorDevice(vol2_backend)
+
+    cvol = CVolume(pyocf_ctx)
+    cvol.add(vol1)
+    cvol.add(vol2)
+    cvol.destroy()
 
 
-@pytest.mark.skip(reason="not implemented")
 def test_add_max_subvolumes(pyocf_ctx):
     """
     title: Add maximum number of subvolumes.
@@ -69,10 +84,36 @@ def test_add_max_subvolumes(pyocf_ctx):
     requirements:
       - composite_volume::max_composite_volumes
     """
-    pass
+
+    cvol = CVolume(pyocf_ctx)
+
+    for i in range(16):
+        vol = RamVolume(S.from_MiB(1))
+        cvol.add(vol)
+
+    vol = RamVolume(S.from_MiB(1))
+    with pytest.raises(OcfError):
+        cvol.add(vol)
+
+    cvol.destroy()
+
+
+def _cvol_io(cvol, addr, size, func, flags=0):
+    io = cvol.new_io(
+        queue=None, addr=addr, length=size, direction=IoDir.WRITE, io_class=0, flags=flags,
+    )
+    completion = OcfCompletion([("err", c_int)])
+    io.callback = completion.callback
+    data = Data(byte_count=size)
+    io.set_data(data, 0)
+
+    submit_fn = getattr(io, func)
+    submit_fn()
+    completion.wait()
+
+    return int(completion.results["err"])
 
 
-@pytest.mark.skip(reason="not implemented")
 def test_basic_volume_operations(pyocf_ctx):
     """
     title: Perform basic volume operations.
@@ -93,7 +134,56 @@ def test_basic_volume_operations(pyocf_ctx):
       - composite_volume::volume_api
       - composite_volume::io_request_passing
     """
-    pass
+    count = {"flush": 0, "discard": 0, "io": 0}
+    expected = {"flush": 0, "discard": 0, "io": 0}
+
+    pyocf_ctx.register_volume_type(TraceDevice)
+
+    addr = S.from_KiB(512).B
+    size = S.from_KiB(4).B
+
+    def trace(vol, io, io_type):
+        if io_type == TraceDevice.IoType.Flush or int(io.contents._flags) & IoFlags.FLUSH:
+            count["flush"] += 1
+        elif io_type == TraceDevice.IoType.Discard:
+            count["discard"] += 1
+        else:
+            assert io_type == TraceDevice.IoType.Data
+            count["io"] += 1
+        assert io.contents._dir == IoDir.WRITE
+        assert io.contents._addr == addr
+        assert io.contents._bytes == size
+
+        return True
+
+    backend = RamVolume(S.from_MiB(1))
+    trace_dev = TraceDevice(backend, trace_fcn=trace)
+
+    cvol = CVolume(pyocf_ctx)
+
+    cvol.add(trace_dev)
+    cvol.open()
+
+    # verify data properly propagated
+    ret = _cvol_io(cvol, addr, size, "submit")
+    assert ret == 0
+    expected["io"] += 1
+    assert expected == count
+
+    # verify flush properly propagated
+    ret = _cvol_io(cvol, addr, size, "submit_flush", IoFlags.FLUSH)
+    assert ret == 0
+    expected["flush"] += 1
+    assert expected == count
+
+    # verify discard properly propagated
+    ret = _cvol_io(cvol, addr, size, "submit_discard")
+    assert ret == 0
+    expected["discard"] += 1
+    assert expected == count
+
+    cvol.close()
+    cvol.destroy()
 
 
 @pytest.mark.skip(reason="not implemented")

tests/functional/tests/management/test_start_stop.py

@@ -4,7 +4,15 @@
 #
 
 import logging
-from ctypes import c_int, c_void_p, byref, c_uint32
+from ctypes import (
+    c_int,
+    c_void_p,
+    byref,
+    c_uint32,
+    cast,
+    create_string_buffer,
+    c_char_p,
+)
 from random import randrange
 from itertools import count
 
@@ -19,13 +27,22 @@ from pyocf.types.cache import (
     CacheConfig,
     PromotionPolicy,
     Backfill,
+    CacheDeviceConfig,
+    CacheAttachConfig,
 )
 from pyocf.types.core import Core
 from pyocf.types.ctx import OcfCtx
 from pyocf.types.data import Data
 from pyocf.types.io import IoDir
 from pyocf.types.queue import Queue
-from pyocf.types.shared import OcfError, OcfCompletion, CacheLineSize, SeqCutOffPolicy
+from pyocf.types.shared import (
+    Uuid,
+    OcfError,
+    OcfErrorCode,
+    OcfCompletion,
+    CacheLineSize,
+    SeqCutOffPolicy,
+)
 from pyocf.types.volume import Volume, RamVolume
 from pyocf.types.volume_core import CoreVolume
 from pyocf.utils import Size
@@ -234,7 +251,7 @@ def test_start_stop_multiple(pyocf_ctx):
         cache_line_size = CacheLineSize(size)
 
         cache = Cache.start_on_device(
-            cache_device, name=cache_name, cache_mode=cache_mode, cache_line_size=cache_line_size
+            cache_device, name=cache_name, cache_mode=cache_mode, cache_line_size=cache_line_size,
         )
         caches.append(cache)
         stats = cache.get_stats()
@@ -264,7 +281,7 @@ def test_100_start_stop(pyocf_ctx):
         cache_line_size = CacheLineSize(size)
 
         cache = Cache.start_on_device(
-            cache_device, name=cache_name, cache_mode=cache_mode, cache_line_size=cache_line_size
+            cache_device, name=cache_name, cache_mode=cache_mode, cache_line_size=cache_line_size,
         )
         stats = cache.get_stats()
         assert stats["conf"]["cache_mode"] == cache_mode, "Cache mode"
@@ -378,18 +395,72 @@ def test_start_cache_huge_device(pyocf_ctx_log_buffer, cls):
 @pytest.mark.parametrize("cls", CacheLineSize)
 def test_start_cache_same_device(pyocf_ctx, mode, cls):
     """Adding two caches using the same cache device
-    Check that OCF does not allow for 2 caches using the same cache device to be started
+    Check that OCF does not allow for 2 caches using the same cache device to be started.
+    Low level OCF API is used for attach instead of Cache::attach_device as the latter operates
+    on pyocf Volume objects and this test requires explicit construction of two volumes with
+    identical UUID. Pyocf does not allow for two Volume objects with the same UUID, as these
+    represent a resource that should be uniquely identified by UUID. So we need to create
+    two distinct OCF volumes with identical UUID and pass them to OCF cache attach method.
     """
+    _uuid = "cache_dev"
 
-    cache_device = RamVolume(Size.from_MiB(50))
+    cache_device = RamVolume(Size.from_MiB(50), uuid=_uuid)
-    cache = Cache.start_on_device(cache_device, cache_mode=mode, cache_line_size=cls, name="cache1")
-    cache.get_stats()
 
-    with pytest.raises(OcfError, match="OCF_ERR_NOT_OPEN_EXC"):
+    uuid = Uuid(
-        cache = Cache.start_on_device(
+        _data=cast(create_string_buffer(_uuid.encode("ascii")), c_char_p), _size=len(_uuid) + 1,
-            cache_device, cache_mode=mode, cache_line_size=cls, name="cache2"
     )
-    cache.get_stats()
+
+    lib = OcfLib.getInstance()
+
+    vol1 = c_void_p()
+    vol2 = c_void_p()
+
+    result = lib.ocf_volume_create(byref(vol1), pyocf_ctx.ocf_volume_type[RamVolume], byref(uuid))
+    assert result == 0
+    result = lib.ocf_volume_create(byref(vol2), pyocf_ctx.ocf_volume_type[RamVolume], byref(uuid))
+    assert result == 0
+
+    dev_cfg = CacheDeviceConfig(_volume=vol1, _perform_test=False, _volume_params=None)
+
+    attach_cfg = CacheAttachConfig(
+        _device=dev_cfg,
+        _cache_line_size=cls,
+        _open_cores=True,
+        _force=False,
+        _discard_on_start=False,
+    )
+
+    # start first cache instance
+    cache1 = Cache(pyocf_ctx, cache_mode=mode, cache_line_size=cls, name="cache1")
+    cache1.start_cache()
+    cache1.write_lock()
+    c = OcfCompletion([("cache", c_void_p), ("priv", c_void_p), ("error", c_int)])
+    lib.ocf_mngt_cache_attach(cache1.cache_handle, byref(attach_cfg), c, None)
+    c.wait()
+    cache1.write_unlock()
+    assert not c.results["error"]
+
+    # attempt to start second cache instance on a volume with the same UUID
+    attach_cfg._device._volume = vol2
+    cache2 = Cache(pyocf_ctx, cache_mode=mode, cache_line_size=cls, name="cache2")
+    cache2.start_cache()
+    cache2.write_lock()
+    c = OcfCompletion([("cache", c_void_p), ("priv", c_void_p), ("error", c_int)])
+    lib.ocf_mngt_cache_attach(cache2.cache_handle, byref(attach_cfg), c, None)
+    c.wait()
+    cache2.write_unlock()
+
+    assert c.results["error"]
+    error_code = OcfErrorCode(abs(c.results["error"]))
+    assert error_code == OcfErrorCode.OCF_ERR_NOT_OPEN_EXC
+
+    cache1.stop()
+    cache2.stop()
+
+    lib = OcfLib.getInstance().ocf_volume_destroy(vol1)
+    lib = OcfLib.getInstance().ocf_volume_destroy(vol2)
+
+    del cache_device
 
 
 @pytest.mark.parametrize("mode", CacheMode)