From: Ilya Dryomov <idryomov@gmail.com>
Date: Tue, 24 Feb 2026 11:46:35 +0000 (+0100)
Subject: librbd/mirror: detect trashed snapshots in UnlinkPeerRequest
X-Git-Tag: v21.0.0~197^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=refs%2Fpull%2F67482%2Fhead;p=ceph.git

librbd/mirror: detect trashed snapshots in UnlinkPeerRequest

If two instances of UnlinkPeerRequest race with each other (e.g. due
to rbd-mirror daemon unlinking from a previous mirror snapshot and the
user taking another mirror snapshot at same time), the snapshot that
UnlinkPeerRequest was created for may be in the process of being removed
(which may mean trashed by SnapshotRemoveRequest::trash_snap()) or fully
removed by the time unlink_peer() grabs the image lock.  Because trashed
snapshots weren't handled explicitly, UnlinkPeerRequest could spuriously
fail with EINVAL ("not mirror snapshot" case) instead of the expected
ENOENT ("missing snapshot" case).  This in turn could lead to spurious
ImageReplayer failures with it stopping prematurely.

Fixes: https://tracker.ceph.com/issues/68279
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---

diff --git a/src/librbd/mirror/snapshot/UnlinkPeerRequest.cc b/src/librbd/mirror/snapshot/UnlinkPeerRequest.cc
index e89a43875417..2063cd0ba319 100644
--- a/src/librbd/mirror/snapshot/UnlinkPeerRequest.cc
+++ b/src/librbd/mirror/snapshot/UnlinkPeerRequest.cc
@@ -79,10 +79,13 @@ void UnlinkPeerRequest<I>::unlink_peer() {
     }
   }
 
-  if (r == -ENOENT) {
-    ldout(cct, 15) << "missing snapshot: snap_id=" << m_snap_id << dendl;
+  if (r == -ENOENT ||
+      std::holds_alternative<cls::rbd::TrashSnapshotNamespace>(
+        snap_namespace)) {
+    ldout(cct, 15) << "missing or trashed snapshot: snap_id=" << m_snap_id
+                   << dendl;
     m_image_ctx->image_lock.unlock_shared();
-    finish(r);
+    finish(-ENOENT);
     return;
   }
 
diff --git a/src/test/librbd/mirror/snapshot/test_mock_UnlinkPeerRequest.cc b/src/test/librbd/mirror/snapshot/test_mock_UnlinkPeerRequest.cc
index 96e1cb9ee8db..4626580c4635 100644
--- a/src/test/librbd/mirror/snapshot/test_mock_UnlinkPeerRequest.cc
+++ b/src/test/librbd/mirror/snapshot/test_mock_UnlinkPeerRequest.cc
@@ -291,6 +291,31 @@ TEST_F(TestMockMirrorSnapshotUnlinkPeerRequest, SnapshotDNE) {
   ASSERT_EQ(-ENOENT, ctx.wait());
 }
 
+TEST_F(TestMockMirrorSnapshotUnlinkPeerRequest, TrashedSnapshot) {
+  REQUIRE_FORMAT_V2();
+
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  cls::rbd::TrashSnapshotNamespace ns{
+    cls::rbd::SNAPSHOT_NAMESPACE_TYPE_MIRROR, "mirror_snap"};
+  auto snap_id = snap_create(mock_image_ctx, ns, "trash_snap");
+
+  expect_get_snap_info(mock_image_ctx, snap_id);
+
+  InSequence seq;
+
+  expect_is_refresh_required(mock_image_ctx, true);
+  expect_refresh_image(mock_image_ctx, 0);
+
+  C_SaferCond ctx;
+  auto req = new MockUnlinkPeerRequest(&mock_image_ctx, snap_id, "peer_uuid",
+                                       true, &ctx);
+  req->send();
+  ASSERT_EQ(-ENOENT, ctx.wait());
+}
+
 TEST_F(TestMockMirrorSnapshotUnlinkPeerRequest, PeerDNE) {
   REQUIRE_FORMAT_V2();