From 30e05d8bdbce06c87290be1bd0ec99525d82c34f Mon Sep 17 00:00:00 2001
From: Jason Dillaman <dillaman@redhat.com>
Date: Tue, 11 Sep 2018 21:52:05 -0400
Subject: [PATCH] luminous: librbd: fixed assert when flattening clone with
 zero overlap

Fixes: http://tracker.ceph.com/issues/35702
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
(cherry picked from commit 8e90354)

 Conflicts:
	src/librbd/Operations.cc
	src/test/librbd/test_librbd.cc
---
 src/librbd/Operations.cc               |  1 -
 src/librbd/operation/FlattenRequest.cc |  2 +-
 src/test/librbd/test_librbd.cc         | 32 ++++++++++++++++++++++++++
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/librbd/Operations.cc b/src/librbd/Operations.cc
index bc118915dc407..e9e8fa4b76fdf 100644
--- a/src/librbd/Operations.cc
+++ b/src/librbd/Operations.cc
@@ -398,7 +398,6 @@ void Operations<I>::execute_flatten(ProgressContext &prog_ctx,
   }
 
   ::SnapContext snapc = m_image_ctx.snapc;
-  assert(m_image_ctx.parent != NULL);
 
   uint64_t overlap;
   int r = m_image_ctx.get_parent_overlap(CEPH_NOSNAP, &overlap);
diff --git a/src/librbd/operation/FlattenRequest.cc b/src/librbd/operation/FlattenRequest.cc
index 78cca8d38dc55..35c947c044362 100644
--- a/src/librbd/operation/FlattenRequest.cc
+++ b/src/librbd/operation/FlattenRequest.cc
@@ -130,7 +130,7 @@ bool FlattenRequest<I>::send_update_header() {
     RWLock::RLocker parent_locker(image_ctx.parent_lock);
     // stop early if the parent went away - it just means
     // another flatten finished first, so this one is useless.
-    if (!image_ctx.parent) {
+    if (image_ctx.parent_md.spec.pool_id == -1) {
       ldout(cct, 5) << "image already flattened" << dendl;
       return true;
     }
diff --git a/src/test/librbd/test_librbd.cc b/src/test/librbd/test_librbd.cc
index 67e348a40cdc9..a4e6d1d268df1 100644
--- a/src/test/librbd/test_librbd.cc
+++ b/src/test/librbd/test_librbd.cc
@@ -6195,6 +6195,38 @@ TEST_F(TestLibRBD, TestTrashMoveAndRestore) {
   ASSERT_TRUE(found);
 }
 
+TEST_F(TestLibRBD, ZeroOverlapFlatten) {
+  REQUIRE_FEATURE(RBD_FEATURE_LAYERING);
+
+  librados::IoCtx ioctx;
+  ASSERT_EQ(0, _rados.ioctx_create(m_pool_name.c_str(), ioctx));
+
+  librbd::RBD rbd;
+  librbd::Image parent_image;
+  std::string name = get_temp_image_name();
+
+  uint64_t size = 1;
+  int order = 0;
+
+  ASSERT_EQ(0, create_image_pp(rbd, ioctx, name.c_str(), size, &order));
+  ASSERT_EQ(0, rbd.open(ioctx, parent_image, name.c_str(), NULL));
+
+  uint64_t features;
+  ASSERT_EQ(0, parent_image.features(&features));
+
+  ASSERT_EQ(0, parent_image.snap_create("snap"));
+  ASSERT_EQ(0, parent_image.snap_protect("snap"));
+
+  std::string clone_name = this->get_temp_image_name();
+  ASSERT_EQ(0, rbd.clone(ioctx, name.c_str(), "snap", ioctx, clone_name.c_str(),
+                         features, &order));
+
+  librbd::Image clone_image;
+  ASSERT_EQ(0, rbd.open(ioctx, clone_image, clone_name.c_str(), NULL));
+  ASSERT_EQ(0, clone_image.resize(0));
+  ASSERT_EQ(0, clone_image.flatten());
+}
+
 // poorman's assert()
 namespace ceph {
   void __ceph_assert_fail(const char *assertion, const char *file, int line,
-- 
2.39.5