librbd: migration abort should revert data back to the original image

If the migration destination image was modified and then the migration
was aborted, we need to copy the data back to the source image to avoid
losing data. For simplicity we will only revert the HEAD revision state
and will not attempt to copy new snapshots on the destination image
back to the source.

Fixes: https://tracker.ceph.com/issues/41394
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
(cherry picked from commit 5bd15da8be09a4e7644d411a0b0c132e5b795393)

Conflicts:
	src/librbd/api/Migration.cc: trivial resolution
(cherry picked from commit f94c276accb8c9f4096b3bffc95362a921f2a2a5)

Conflicts:
        src/librbd/api/Migration.cc: snapshot-based mirroring changes

diff --git a/src/librbd/api/Migration.cc b/src/librbd/api/Migration.cc
index 813eeeeca249f24e29fe57845b80b987cde6cf9e..7fbc878f4ad5dbbf911fcbf139838ce89928ebd7 100644 (file)
--- a/src/librbd/api/Migration.cc
+++ b/src/librbd/api/Migration.cc
@@ -17,6 +17,7 @@
 #include "librbd/api/Image.h"
 #include "librbd/api/Snapshot.h"
 #include "librbd/api/Trash.h"
+#include "librbd/deep_copy/ImageCopyRequest.h"
 #include "librbd/deep_copy/MetadataCopyRequest.h"
 #include "librbd/deep_copy/SnapshotCopyRequest.h"
 #include "librbd/exclusive_lock/Policy.h"
@@ -335,6 +336,30 @@ int open_source_image(librados::IoCtx& io_ctx, const std::string &image_name,
   return 0;
 }
 
+class SteppedProgressContext : public ProgressContext {
+public:
+  SteppedProgressContext(ProgressContext* progress_ctx, size_t total_steps)
+    : m_progress_ctx(progress_ctx), m_total_steps(total_steps) {
+  }
+
+  void next_step() {
+    ceph_assert(m_current_step < m_total_steps);
+    ++m_current_step;
+  }
+
+  int update_progress(uint64_t object_number,
+                      uint64_t object_count) override {
+    return m_progress_ctx->update_progress(
+      object_number + (object_count * (m_current_step - 1)),
+      object_count * m_total_steps);
+  }
+
+private:
+  ProgressContext* m_progress_ctx;
+  size_t m_total_steps;
+  size_t m_current_step = 1;
+};
+
 } // anonymous namespace
 
 template <typename I>
@@ -806,6 +831,11 @@ int Migration<I>::abort() {
       return r;
     }
 
+    // copy dst HEAD -> src HEAD
+    SteppedProgressContext progress_ctx(m_prog_ctx, 2);
+    revert_data(dst_image_ctx, m_src_image_ctx, &progress_ctx);
+    progress_ctx.next_step();
+
     ldout(m_cct, 10) << "relinking children" << dendl;
     r = relink_children(dst_image_ctx, m_src_image_ctx);
     if (r < 0) {
@@ -849,7 +879,7 @@ int Migration<I>::abort() {
     ImageCtx::get_thread_pool_instance(m_cct, &thread_pool, &op_work_queue);
     C_SaferCond on_remove;
     auto req = librbd::image::RemoveRequest<>::create(
-      m_dst_io_ctx, dst_image_ctx, false, false, *m_prog_ctx, op_work_queue,
+      m_dst_io_ctx, dst_image_ctx, false, false, progress_ctx, op_work_queue,
       &on_remove);
     req->send();
     r = on_remove.wait();
@@ -1799,6 +1829,60 @@ int Migration<I>::remove_src_image() {
   return 0;
 }
 
+template <typename I>
+int Migration<I>::revert_data(I* src_image_ctx, I* dst_image_ctx,
+                              ProgressContext* prog_ctx) {
+  ldout(m_cct, 10) << dendl;
+
+  cls::rbd::MigrationSpec migration_spec;
+  int r = cls_client::migration_get(&src_image_ctx->md_ctx,
+                                    src_image_ctx->header_oid,
+                                    &migration_spec);
+
+  if (r < 0) {
+    lderr(m_cct) << "failed retrieving migration header: " << cpp_strerror(r)
+                 << dendl;
+    return r;
+  }
+
+  if (migration_spec.header_type != cls::rbd::MIGRATION_HEADER_TYPE_DST) {
+    lderr(m_cct) << "unexpected migration header type: "
+                 << migration_spec.header_type << dendl;
+    return -EINVAL;
+  }
+
+  uint64_t src_snap_id_start = 0;
+  uint64_t src_snap_id_end = CEPH_NOSNAP;
+  uint64_t dst_snap_id_start = 0;
+  if (!migration_spec.snap_seqs.empty()) {
+    src_snap_id_start = migration_spec.snap_seqs.rbegin()->second;
+  }
+
+  // we only care about the HEAD revision so only add a single mapping to
+  // represent the most recent state
+  SnapSeqs snap_seqs;
+  snap_seqs[CEPH_NOSNAP] = CEPH_NOSNAP;
+
+  ldout(m_cct, 20) << "src_snap_id_start=" << src_snap_id_start << ", "
+                   << "src_snap_id_end=" << src_snap_id_end << ", "
+                   << "snap_seqs=" << snap_seqs << dendl;
+
+  C_SaferCond ctx;
+  auto request = deep_copy::ImageCopyRequest<I>::create(
+    src_image_ctx, dst_image_ctx, src_snap_id_start, src_snap_id_end,
+    dst_snap_id_start, false, {}, snap_seqs, prog_ctx, &ctx);
+  request->send();
+
+  r = ctx.wait();
+  if (r < 0) {
+    lderr(m_cct) << "error reverting destination image data blocks back to "
+                 << "source image: " << cpp_strerror(r) << dendl;
+    return r;
+  }
+
+  return 0;
+}
+
 } // namespace api
 } // namespace librbd
 

diff --git a/src/librbd/api/Migration.h b/src/librbd/api/Migration.h
index 4261eea5815ddb86711c172cb0fc0c9341f6a8c0..52a4517bb14a0a41b6b63b017d95211114699181 100644 (file)
--- a/src/librbd/api/Migration.h
+++ b/src/librbd/api/Migration.h
@@ -92,6 +92,9 @@ private:
                    const librbd::snap_info_t &src_snap,
                    const librbd::linked_image_spec_t &child_image,
                    bool migration_abort, bool reattach_child);
+
+  int revert_data(ImageCtxT* src_image_ctx, ImageCtxT* dst_image_ctx,
+                  ProgressContext *prog_ctx);
 };
 
 } // namespace api

diff --git a/src/test/librbd/test_Migration.cc b/src/test/librbd/test_Migration.cc
index 164a5ba9cfb58339572ab60358240c4c2463d524..29bbdfbd5db22a053c75274cde6d57926319b060 100644 (file)
--- a/src/test/librbd/test_Migration.cc
+++ b/src/test/librbd/test_Migration.cc
@@ -1111,6 +1111,28 @@ TEST_F(TestMigration, AbortInUseImage) {
                                                     no_op));
 }
 
+TEST_F(TestMigration, AbortWithoutSnapshots) {
+  test_no_snaps();
+  migration_prepare(m_ioctx, m_image_name);
+  migration_status(RBD_IMAGE_MIGRATION_STATE_PREPARED);
+  test_no_snaps();
+  migration_abort(m_ioctx, m_image_name);
+}
+
+TEST_F(TestMigration, AbortWithSnapshots) {
+  test_snaps();
+  migration_prepare(m_ioctx, m_image_name);
+  migration_status(RBD_IMAGE_MIGRATION_STATE_PREPARED);
+
+  test_no_snaps();
+  flush();
+  ASSERT_EQ(0, TestFixture::snap_create(*m_ictx, "dst-only-snap"));
+
+  test_no_snaps();
+
+  migration_abort(m_ioctx, m_image_name);
+}
+
 TEST_F(TestMigration, CloneV1Parent)
 {
   const uint32_t CLONE_FORMAT = 1;