From 1baba64e213cb808804796575d3f7969cf37a3c6 Mon Sep 17 00:00:00 2001
From: Jason Dillaman <dillaman@redhat.com>
Date: Tue, 8 Dec 2020 14:16:49 -0500
Subject: [PATCH] librbd/deep_copy: added new migrating flag to object copy

The migration operation and the copyup state machine will set
this flag when attempting to perform a deep-copy due to a
live-migration.

This flag will prevent a possible race condition between the
start of the object deep-copy when migration was enabled and
the writing portion of the deep-copy when migration might
have completed via external means.

Fixes: https://tracker.ceph.com/issues/45694
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
---
 src/librbd/deep_copy/ObjectCopyRequest.cc | 6 ++++--
 src/librbd/deep_copy/Types.h              | 3 ++-
 src/librbd/io/CopyupRequest.cc            | 2 +-
 src/librbd/operation/MigrateRequest.cc    | 2 +-
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/librbd/deep_copy/ObjectCopyRequest.cc b/src/librbd/deep_copy/ObjectCopyRequest.cc
index 21153cfed08..80b06c15cfb 100644
--- a/src/librbd/deep_copy/ObjectCopyRequest.cc
+++ b/src/librbd/deep_copy/ObjectCopyRequest.cc
@@ -339,7 +339,9 @@ void ObjectCopyRequest<I>::send_write_object() {
                    << "dst_snaps=" << dst_snap_ids << dendl;
 
   librados::ObjectWriteOperation op;
-  if (!m_dst_image_ctx->migration_info.empty()) {
+
+  bool migration = ((m_flags & OBJECT_COPY_REQUEST_FLAG_MIGRATION) != 0);
+  if (migration) {
     ldout(m_cct, 20) << "assert_snapc_seq=" << dst_snap_seq << dendl;
     cls_client::assert_snapc_seq(&op, dst_snap_seq,
                                  cls::rbd::ASSERT_SNAPC_SEQ_GT_SNAPSET_SEQ);
@@ -381,7 +383,7 @@ void ObjectCopyRequest<I>::send_write_object() {
     }
   }
 
-  if (op.size() == (m_dst_image_ctx->migration_info.empty() ? 0 : 1)) {
+  if (op.size() == (migration ? 1 : 0)) {
     handle_write_object(0);
     return;
   }
diff --git a/src/librbd/deep_copy/Types.h b/src/librbd/deep_copy/Types.h
index 0b24dae2bec..e6aa980494b 100644
--- a/src/librbd/deep_copy/Types.h
+++ b/src/librbd/deep_copy/Types.h
@@ -12,7 +12,8 @@ namespace librbd {
 namespace deep_copy {
 
 enum {
-  OBJECT_COPY_REQUEST_FLAG_FLATTEN = 1U << 0,
+  OBJECT_COPY_REQUEST_FLAG_FLATTEN   = 1U << 0,
+  OBJECT_COPY_REQUEST_FLAG_MIGRATION = 1U << 1,
 };
 
 typedef std::vector<librados::snap_t> SnapIds;
diff --git a/src/librbd/io/CopyupRequest.cc b/src/librbd/io/CopyupRequest.cc
index 43c856173ce..d70851409fd 100644
--- a/src/librbd/io/CopyupRequest.cc
+++ b/src/librbd/io/CopyupRequest.cc
@@ -258,7 +258,7 @@ void CopyupRequest<I>::deep_copy() {
 
   ldout(cct, 20) << "flatten=" << m_flatten << dendl;
 
-  uint32_t flags = 0;
+  uint32_t flags = deep_copy::OBJECT_COPY_REQUEST_FLAG_MIGRATION;
   if (m_flatten) {
     flags |= deep_copy::OBJECT_COPY_REQUEST_FLAG_FLATTEN;
   }
diff --git a/src/librbd/operation/MigrateRequest.cc b/src/librbd/operation/MigrateRequest.cc
index 487df9970a8..2b9adb77378 100644
--- a/src/librbd/operation/MigrateRequest.cc
+++ b/src/librbd/operation/MigrateRequest.cc
@@ -128,7 +128,7 @@ private:
     } else {
       ceph_assert(image_ctx.parent != nullptr);
 
-      uint32_t flags = 0;
+      uint32_t flags = deep_copy::OBJECT_COPY_REQUEST_FLAG_MIGRATION;
       if (image_ctx.migration_info.flatten) {
         flags |= deep_copy::OBJECT_COPY_REQUEST_FLAG_FLATTEN;
       }
-- 
2.39.5