1 files changed, 97 insertions, 0 deletions
diff --git a/src/mds/inode_backtrace.h b/src/mds/inode_backtrace.h
new file mode 100644
index 00000000..7c60865c
--- /dev/null
+++ b/src/mds/inode_backtrace.h
@@ -0,0 +1,97 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- 
+// vim: ts=8 sw=2 smarttab
+#ifndef CEPH_INODE_BACKTRACE_H
+#define CEPH_INODE_BACKTRACE_H
+
+#include <string_view>
+
+#include "mdstypes.h"
+
+namespace ceph {
+  class Formatter;
+}
+
+/** metadata backpointers **/
+
+/*
+ * - inode_backpointer_t is just the _pointer_ portion; it doesn't
+ *   tell us who we point _from_.
+ *
+ * - it _does_ include a version of the source object, so we can look
+ *   at two different pointers (from the same inode) and tell which is
+ *   newer.
+ */
+struct inode_backpointer_t {
+  inodeno_t dirino;    // containing directory ino
+  string dname;        // linking dentry name
+  version_t version;   // child's version at time of backpointer creation
+
+  inode_backpointer_t() : version(0) {}
+  inode_backpointer_t(inodeno_t i, std::string_view d, version_t v) : dirino(i), dname(d), version(v) {}
+
+  void encode(bufferlist& bl) const;
+  void decode(bufferlist::const_iterator &bl);
+  void decode_old(bufferlist::const_iterator &bl);
+  void dump(Formatter *f) const;
+  static void generate_test_instances(list<inode_backpointer_t*>& ls);
+};
+WRITE_CLASS_ENCODER(inode_backpointer_t)
+
+inline bool operator==(const inode_backpointer_t& l, const inode_backpointer_t& r) {
+	return l.dirino == r.dirino && l.version == r.version && l.dname == r.dname;
+}
+
+inline ostream& operator<<(ostream& out, const inode_backpointer_t& ib) {
+  return out << "<" << ib.dirino << "/" << ib.dname << " v" << ib.version << ">";
+}
+
+/*
+ * inode_backtrace_t is a complete ancestor backtraces for a given inode.
+ * we include who _we_ are, so that the backtrace can stand alone (as, say,
+ * an xattr on an object).
+ */
+struct inode_backtrace_t {
+  inodeno_t ino;       // my ino
+  vector<inode_backpointer_t> ancestors;
+  int64_t pool;
+  // we use a set for old_pools to avoid duplicate entries, e.g. setlayout 0, 1, 0
+  set<int64_t> old_pools;
+
+  inode_backtrace_t() : pool(-1) {}
+
+  void encode(bufferlist& bl) const;
+  void decode(bufferlist::const_iterator &bl);
+  void dump(Formatter *f) const;
+  static void generate_test_instances(list<inode_backtrace_t*>& ls);
+
+  /**
+   * Compare two backtraces *for the same inode*.
+   * @pre The backtraces are for the same inode
+   *
+   * @param other The backtrace to compare ourselves with
+   * @param equivalent A bool pointer which will be set to true if
+   * the other backtrace is equivalent to our own (has the same dentries)
+   * @param divergent A bool pointer which will be set to true if
+   * the backtraces have differing entries without versions supporting them
+   *
+   * @returns 1 if we are newer than the other, 0 if equal, -1 if older
+   */
+  int compare(const inode_backtrace_t& other,
+               bool *equivalent, bool *divergent) const;
+};
+WRITE_CLASS_ENCODER(inode_backtrace_t)
+
+inline ostream& operator<<(ostream& out, const inode_backtrace_t& it) {
+  return out << "(" << it.pool << ")" << it.ino << ":" << it.ancestors << "//" << it.old_pools;
+}
+
+inline bool operator==(const inode_backtrace_t& l,
+                       const inode_backtrace_t& r) {
+  return l.ino == r.ino &&
+      l.pool == r.pool &&
+      l.old_pools == r.old_pools &&
+      l.ancestors == r.ancestors;
+}
+
+#endif
+