From 397285a41360be43baac27f8f145d190a13f2aee Mon Sep 17 00:00:00 2001
From: Dan Mick <dan.mick@inktank.com>
Date: Mon, 13 Aug 2012 15:03:07 -0700
Subject: [PATCH] librbd: make get_parent_info look at snapshot-specific info
 when needed

---
 src/librbd/ImageCtx.cc | 14 ++++++++++++++
 src/librbd/ImageCtx.h  |  1 +
 src/librbd/internal.cc | 38 ++++++++++++++++++++++++++++++--------
 3 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/src/librbd/ImageCtx.cc b/src/librbd/ImageCtx.cc
index 5ac44a41747bd..bde095e9922b2 100644
--- a/src/librbd/ImageCtx.cc
+++ b/src/librbd/ImageCtx.cc
@@ -211,6 +211,20 @@ namespace librbd {
     return -ENOENT;
   }
 
+  int ImageCtx::get_snapinfo(snapid_t in_snap_id, SnapInfo **out_snapinfo)
+  {
+    assert(snap_lock.is_locked());
+    map<string, SnapInfo>::iterator it;
+
+    for (it = snaps_by_name.begin(); it != snaps_by_name.end(); it++) {
+      if (it->second.id == in_snap_id) {
+	*out_snapinfo = &(it->second);
+	return 0;
+      }
+    }
+    return -ENOENT;
+  }
+
   int ImageCtx::get_snap_size(string in_snap_name, uint64_t *out_size) const
   {
     assert(snap_lock.is_locked());
diff --git a/src/librbd/ImageCtx.h b/src/librbd/ImageCtx.h
index 986ce1966a5bc..12edf18dacae0 100644
--- a/src/librbd/ImageCtx.h
+++ b/src/librbd/ImageCtx.h
@@ -89,6 +89,7 @@ namespace librbd {
     void snap_unset();
     librados::snap_t get_snap_id(std::string in_snap_name) const;
     int get_snap_name(snapid_t snap_id, std::string *out_snap_name) const;
+    int get_snapinfo(snapid_t snap_id, SnapInfo **out_snapinfo);
     int get_snap_size(std::string in_snap_name, uint64_t *out_size) const;
     void add_snap(std::string in_snap_name, librados::snap_t id,
 		  uint64_t in_size, uint64_t features,
diff --git a/src/librbd/internal.cc b/src/librbd/internal.cc
index daa97eb0b5452..61ce087045771 100644
--- a/src/librbd/internal.cc
+++ b/src/librbd/internal.cc
@@ -874,24 +874,46 @@ namespace librbd {
 
     Mutex::Locker l(ictx->snap_lock);
     Mutex::Locker l2(ictx->parent_lock);
-    if (!ictx->parent)
-      return -ENOENT;
 
+    cls_client::parent_info *parent_info;
+
+    if (ictx->snap_id == CEPH_NOSNAP) {
+      if (!ictx->parent)
+	return 0;
+      parent_info = &(ictx->parent_md);
+    } else {
+      SnapInfo *snapinfo;
+      r = ictx->get_snapinfo(ictx->snap_id, &snapinfo);
+      if (r < 0) {
+	lderr(ictx->cct) << "Can't find snapshot id" << ictx->snap_id << dendl;
+	return r;
+      }
+      parent_info = &(snapinfo->parent);
+      if (parent_info->pool_id == -1)
+	return 0;
+    }
     if (parent_pool_name) {
       Rados rados(ictx->md_ctx);
-      r = rados.pool_reverse_lookup(ictx->parent->md_ctx.get_id(),
-				    parent_pool_name);
+      r = rados.pool_reverse_lookup(parent_info->pool_id, parent_pool_name);
       if (r < 0) {
-	lderr(ictx->cct) << "error looking up pool name" << dendl;
+	lderr(ictx->cct) << "error looking up pool name" << cpp_strerror(r)
+			 << dendl;
       }
     }
 
-    if (parent_snap_name)
-      *parent_snap_name = ictx->parent->snap_name;
+    if (parent_snap_name) {
+      Mutex::Locker l(ictx->parent->snap_lock);
+      r = ictx->parent->get_snap_name(parent_info->snap_id, parent_snap_name);
+      if (r < 0) {
+	lderr(ictx->cct) << "error finding parent snap name: "
+			 << cpp_strerror(r) << dendl;
+	return r;
+      }
+    }
 
     if (parent_name) {
       r = cls_client::dir_get_name(&ictx->parent->md_ctx, RBD_DIRECTORY,
-				   ictx->parent->id, parent_name);
+				   parent_info->image_id, parent_name);
       if (r < 0) {
 	lderr(ictx->cct) << "error getting parent image name: "
 			 << cpp_strerror(r) << dendl;
-- 
2.39.5