From a6e50c245240e37701c6c6674058c16e89785927 Mon Sep 17 00:00:00 2001
From: Yehuda Sadeh <yehuda@hq.newdream.net>
Date: Wed, 26 May 2010 13:57:38 -0700
Subject: [PATCH] rbd: implement snap revert header manipulation via class

---
 src/cls_rbd.cc            | 75 +++++++++++++++++++++++++++++++++++++++
 src/objclass/class_api.cc | 10 ++++++
 src/objclass/objclass.h   |  1 +
 3 files changed, 86 insertions(+)

diff --git a/src/cls_rbd.cc b/src/cls_rbd.cc
index da070fb4ef91b..b667dabb2908f 100644
--- a/src/cls_rbd.cc
+++ b/src/cls_rbd.cc
@@ -20,6 +20,7 @@ CLS_NAME(rbd)
 cls_handle_t h_class;
 cls_method_handle_t h_snapshots_list;
 cls_method_handle_t h_snapshot_add;
+cls_method_handle_t h_snapshot_revert;
 
 static int snap_read_header(cls_method_context_t hctx, bufferlist& bl)
 {
@@ -164,6 +165,79 @@ int snapshot_add(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
   return 0;
 }
 
+int snapshot_revert(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
+{
+  bufferlist bl;
+  struct rbd_obj_header_ondisk *header;
+  bufferlist newbl;
+  bufferptr header_bp(sizeof(*header));
+  struct rbd_obj_snap_ondisk *new_snaps;
+
+  int rc = snap_read_header(hctx, bl);
+  if (rc < 0)
+    return rc;
+
+  header = (struct rbd_obj_header_ondisk *)bl.c_str();
+
+  int snaps_id_ofs = sizeof(*header);
+  int len = snaps_id_ofs;
+  int names_ofs = snaps_id_ofs + sizeof(*new_snaps) * header->snap_count;
+  const char *snap_name;
+  const char *snap_names = ((char *)header) + names_ofs;
+  const char *end = snap_names + header->snap_names_len;
+  bufferlist::iterator iter = in->begin();
+  string s;
+  uint64_t snap_id;
+  int i;
+  bool found = false;
+  struct rbd_obj_snap_ondisk snap;
+
+  try {
+    ::decode(s, iter);
+  } catch (buffer::error *err) {
+    return -EINVAL;
+  }
+  snap_name = s.c_str();
+
+  for (i = 0; snap_names < end; i++) {
+    if (strcmp(snap_names, snap_name) == 0) {
+      snap = header->snaps[i];
+      found = true;
+      break;
+    }
+    snap_names += strlen(snap_names);
+  }
+  if (!found)
+    return -ENOENT;
+
+  header->image_size = snap.image_size;
+  header->snap_seq = header->snap_seq + 1;
+
+  snap_names += strlen(snap_names);
+  i++;
+
+  header->snap_count = header->snap_count - i;
+  bufferptr new_names_bp(end - snap_names);
+  bufferptr new_snaps_bp(sizeof(header->snaps[0]) * header->snap_count);
+
+  memcpy(header_bp.c_str(), header, sizeof(*header));
+  if (header->snap_count) {
+    char *new_snap_names;
+    memcpy(new_snaps_bp.c_str(), header->snaps + i, sizeof(header->snaps[0]) * header->snap_count);
+    memcpy(new_names_bp.c_str(), snap_names, end - snap_names);
+    newbl.push_back(new_snaps_bp);
+    newbl.push_back(new_names_bp);
+  }
+
+  rc = cls_cxx_write(hctx, 0, len, &newbl);
+  if (rc < 0)
+    return rc;
+
+  ::encode(snap.id, *out);
+
+  return 0;
+}
+
 void class_init()
 {
   CLS_LOG("Loaded rbd class!");
@@ -171,6 +245,7 @@ void class_init()
   cls_register("rbd", &h_class);
   cls_register_cxx_method(h_class, "snap_list", CLS_METHOD_RD, snapshots_list, &h_snapshots_list);
   cls_register_cxx_method(h_class, "snap_add", CLS_METHOD_RD | CLS_METHOD_WR, snapshot_add, &h_snapshot_add);
+  cls_register_cxx_method(h_class, "snap_revert", CLS_METHOD_RD | CLS_METHOD_WR, snapshot_revert, &h_snapshot_revert);
 
   return;
 }
diff --git a/src/objclass/class_api.cc b/src/objclass/class_api.cc
index b2ee1889db93c..bb0d6de725e2d 100644
--- a/src/objclass/class_api.cc
+++ b/src/objclass/class_api.cc
@@ -210,3 +210,13 @@ int cls_cxx_replace(cls_method_context_t hctx, int ofs, int len, bufferlist *inb
   return (*pctx)->pg->do_osd_ops(*pctx, ops, outbl);
 }
 
+int cls_cxx_snap_revert(cls_method_context_t hctx, snapid_t snapid)
+{
+  ReplicatedPG::OpContext **pctx = (ReplicatedPG::OpContext **)hctx;
+  vector<OSDOp> ops(1);
+  ops[0].op.op = CEPH_OSD_OP_ROLLBACK;
+  ops[0].op.snap.snapid = snapid;
+  bufferlist outbl;
+  return (*pctx)->pg->do_osd_ops(*pctx, ops, outbl);
+}
+
diff --git a/src/objclass/objclass.h b/src/objclass/objclass.h
index 74ad231c9f015..a07f259d1f699 100644
--- a/src/objclass/objclass.h
+++ b/src/objclass/objclass.h
@@ -84,6 +84,7 @@ extern int cls_register_cxx_method(cls_handle_t hclass, const char *method, int
 extern int cls_cxx_read(cls_method_context_t hctx, int ofs, int len, bufferlist *bl);
 extern int cls_cxx_write(cls_method_context_t hctx, int ofs, int len, bufferlist *bl);
 extern int cls_cxx_replace(cls_method_context_t hctx, int ofs, int len, bufferlist *bl);
+extern int cls_cxx_snap_revert(cls_method_context_t hctx, snapid_t snapid);
 
 
 #endif
-- 
2.39.5