[PATCH] reinstate ceph cluster_snap support

[Alexandre Oliva <oliva@gnu.org>]

This patch brings back and updates (for dumpling) the code originally
introduced to support “ceph osd cluster_snap <snap>”, that was disabled
and partially removed before cuttlefish.

Some minimal testing appears to indicate this even works: the modified
mon actually generated an osdmap with the cluster_snap request, and
starting a modified osd that was down and letting it catch up caused
the osd to take the requested snapshot.  I see no reason why it
wouldn't have taken it if it was up and running, so...  Why was this
feature disabled in the first place?

Signed-off-by: Alexandre Oliva <oliva@gnu.org>
---
 src/mon/MonCommands.h |    6 ++++--
 src/mon/OSDMonitor.cc |   11 +++++++----
 src/osd/OSD.cc        |   13 +++++++++++++
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/mon/MonCommands.h b/src/mon/MonCommands.h
index 8e9c2bb..225c687 100644
--- a/src/mon/MonCommands.h
+++ b/src/mon/MonCommands.h
@@ -431,8 +431,10 @@ COMMAND("osd set " \
 COMMAND("osd unset " \
 	"name=key,type=CephChoices,strings=pause|noup|nodown|noout|noin|nobackfill|norecover|noscrub|nodeep-scrub", \
 	"unset <key>", "osd", "rw", "cli,rest")
-COMMAND("osd cluster_snap", "take cluster snapshot (disabled)", \
-	"osd", "r", "")
+COMMAND("osd cluster_snap " \
+	"name=snap,type=CephString", \
+	"take cluster snapshot",	\
+	"osd", "r", "cli")
 COMMAND("osd down " \
 	"type=CephString,name=ids,n=N", \
 	"set osd(s) <id> [<id>...] down", "osd", "rw", "cli,rest")
diff --git a/src/mon/OSDMonitor.cc b/src/mon/OSDMonitor.cc
index 07022ae..9bf9511 100644
--- a/src/mon/OSDMonitor.cc
+++ b/src/mon/OSDMonitor.cc
@@ -3099,10 +3099,13 @@ bool OSDMonitor::prepare_command(MMonCommand *m)
       return prepare_unset_flag(m, CEPH_OSDMAP_NODEEP_SCRUB);
 
   } else if (prefix == "osd cluster_snap") {
-    // ** DISABLE THIS FOR NOW **
-    ss << "cluster snapshot currently disabled (broken implementation)";
-    // ** DISABLE THIS FOR NOW **
-
+    string snap;
+    cmd_getval(g_ceph_context, cmdmap, "snap", snap);
+    pending_inc.cluster_snapshot = snap;
+    ss << "creating cluster snap " << snap;
+    getline(ss, rs);
+    wait_for_finished_proposal(new Monitor::C_Command(mon, m, 0, rs, get_last_committed()));
+    return true;
   } else if (prefix == "osd down" ||
 	     prefix == "osd out" ||
 	     prefix == "osd in" ||
diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
index 1a77dae..e41a6b3 100644
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -5022,6 +5022,19 @@ void OSD::handle_osd_map(MOSDMap *m)
     assert(0 == "MOSDMap lied about what maps it had?");
   }
 
+  // check for cluster snapshots
+  for (epoch_t cur = superblock.current_epoch + 1; cur <= m->get_last(); cur++) {
+    OSDMapRef newmap = get_map(cur);
+    string cluster_snap = newmap->get_cluster_snapshot();
+    if (cluster_snap.length() == 0)
+      continue;
+
+    dout(0) << "creating cluster snapshot '" << cluster_snap << "'" << dendl;
+    int r = store->snapshot(cluster_snap);
+    if (r)
+      dout(0) << "failed to create cluster snapshot: " << cpp_strerror(r) << dendl;
+  }
+
   if (superblock.oldest_map) {
     int num = 0;
     epoch_t min(

-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer
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