1 files changed, 61 insertions, 0 deletions
diff --git a/src/librbd/deep_copy/Utils.cc b/src/librbd/deep_copy/Utils.cc
new file mode 100644
index 000000000..c2dd25020
--- /dev/null
+++ b/src/librbd/deep_copy/Utils.cc
@@ -0,0 +1,61 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "common/debug.h"
+#include "Utils.h"
+#include <set>
+
+namespace librbd {
+namespace deep_copy {
+namespace util {
+
+#define dout_subsys ceph_subsys_rbd
+#undef dout_prefix
+#define dout_prefix *_dout << "librbd::deep_copy::util::" << __func__ << ": "
+
+void compute_snap_map(CephContext* cct,
+                      librados::snap_t src_snap_id_start,
+                      librados::snap_t src_snap_id_end,
+                      const SnapIds& dst_snap_ids,
+                      const SnapSeqs &snap_seqs,
+                      SnapMap *snap_map) {
+  std::set<librados::snap_t> ordered_dst_snap_ids{
+    dst_snap_ids.begin(), dst_snap_ids.end()};
+  auto dst_snap_id_it = ordered_dst_snap_ids.begin();
+
+  SnapIds snap_ids;
+  for (auto &it : snap_seqs) {
+    // ensure all dst snap ids are included in the mapping table since
+    // deep copy will skip non-user snapshots
+    while (dst_snap_id_it != ordered_dst_snap_ids.end()) {
+      if (*dst_snap_id_it < it.second) {
+        snap_ids.insert(snap_ids.begin(), *dst_snap_id_it);
+      } else if (*dst_snap_id_it > it.second) {
+        break;
+      }
+      ++dst_snap_id_it;
+    }
+
+    // we should only have the HEAD revision in the the last snap seq
+    ceph_assert(snap_ids.empty() || snap_ids[0] != CEPH_NOSNAP);
+    snap_ids.insert(snap_ids.begin(), it.second);
+
+    if (it.first < src_snap_id_start) {
+      continue;
+    } else if (it.first > src_snap_id_end) {
+      break;
+    }
+
+    (*snap_map)[it.first] = snap_ids;
+  }
+
+  ldout(cct, 10) << "src_snap_id_start=" << src_snap_id_start << ", "
+                 << "src_snap_id_end=" << src_snap_id_end << ", "
+                 << "dst_snap_ids=" << dst_snap_ids << ", "
+                 << "snap_seqs=" << snap_seqs << ", "
+                 << "snap_map=" << *snap_map << dendl;
+}
+
+} // namespace util
+} // namespace deep_copy
+} // namespace librbd