From f74426acb2ecdd09c6b1c4fe5e11ddb16ba3ac0e Mon Sep 17 00:00:00 2001
From: Robert Baldyga <robert.baldyga@unvertical.com>
Date: Fri, 16 Oct 2026 00:16:41 +0200
Subject: [PATCH] mngt: Report incompatible metadata as found on attach

Attaching a device that holds metadata created by a different OCF or
adapter version, or in a different block mode, failed with the specific
incompatibility error instead of OCF_ERR_METADATA_FOUND. As a result
the adapter could not tell the user that the device contains metadata
which has to be discarded with --force.

The detailed reason is still logged by the superblock validation.

Signed-off-by: Robert Baldyga <robert.baldyga@unvertical.com>
---
 src/mngt/ocf_mngt_cache.c                     | 27 ++++++++++-------
 .../tests/management/test_attach_cache.py     | 29 +++++++++++++++++++
 2 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/src/mngt/ocf_mngt_cache.c b/src/mngt/ocf_mngt_cache.c
index 00f13033..4f259075 100644
--- a/src/mngt/ocf_mngt_cache.c
+++ b/src/mngt/ocf_mngt_cache.c
@@ -1319,19 +1319,24 @@ static void _ocf_mngt_attach_read_properties_end(void *priv, int error,
 {
 	struct ocf_cache_attach_context *context = priv;
 
-	if (error != -OCF_ERR_NO_METADATA) {
-		if (!error) {
-			/*
-			 * To prevent silent metadata overriding, return error if old
-			 * metadata was detected when attempting to attach cache.
-			 */
-			OCF_PL_FINISH_RET(context->pipeline, -OCF_ERR_METADATA_FOUND);
-		}
+	switch (error) {
+	case -OCF_ERR_NO_METADATA:
+		/* No metadata exists on the device */
+		OCF_PL_NEXT_RET(context->pipeline);
+	case 0:
+	case -OCF_ERR_METADATA_VER:
+	case -OCF_ERR_ADAPTER_MISMATCH:
+	case -OCF_ERR_ADAPTER_VER:
+	case -OCF_ERR_BLOCK_MODE_MISMATCH:
+		/*
+		 * To prevent silent metadata overriding, return error if old
+		 * metadata was detected when attempting to attach cache - also
+		 * if it was created by incompatible OCF or adapter version.
+		 */
+		OCF_PL_FINISH_RET(context->pipeline, -OCF_ERR_METADATA_FOUND);
+	default:
 		OCF_PL_FINISH_RET(context->pipeline, error);
 	}
-
-	/* No metadata exists on the device */
-	OCF_PL_NEXT_RET(context->pipeline);
 }
 
 static void _ocf_mngt_load_read_properties_end(void *priv, int error,
diff --git a/tests/functional/tests/management/test_attach_cache.py b/tests/functional/tests/management/test_attach_cache.py
index 46f0d7ec..db967c8d 100644
--- a/tests/functional/tests/management/test_attach_cache.py
+++ b/tests/functional/tests/management/test_attach_cache.py
@@ -28,6 +28,7 @@
     CacheLineSize,
     SeqCutOffPolicy,
     OcfError,
+    OcfErrorCode,
 )
 from pyocf.types.volume import RamVolume
 from pyocf.types.volume_core import CoreVolume
@@ -135,6 +136,34 @@ def test_detach_cache_zero_superblock(pyocf_ctx):
     cache.stop()
 
 
+def test_attach_cache_incompatible_metadata_version(pyocf_ctx):
+    """Check if attaching a device holding metadata of a different version
+    without --force option reports that metadata was found.
+    """
+    cache_device = RamVolume(Size.from_MiB(50))
+    cache = Cache.start_on_device(cache_device)
+    cache.stop()
+
+    # metadata_version follows clean_shutdown, dirty_flushed, padding and magic
+    version_offset = 8
+    version = int.from_bytes(
+        cache_device.data[version_offset : version_offset + 4], "little"
+    )
+    cache_device.data[version_offset : version_offset + 4] = (version ^ 0x0100).to_bytes(
+        4, "little"
+    )
+
+    cache = Cache(owner=pyocf_ctx)
+    cache.start_cache()
+
+    with pytest.raises(OcfError) as ex:
+        cache.attach_device(cache_device, force=False)
+    assert ex.value.error_code == OcfErrorCode.OCF_ERR_METADATA_FOUND
+
+    cache.attach_device(cache_device, force=True)
+    cache.stop()
+
+
 def test_reattach_preserves_policy_params(pyocf_ctx):
     """Check if cleaning, promotion and prefetch policy parameters set before
     detach are preserved after the cache device is attached again.