From b960dae6273d9c30e327901e6f4c29e7bcc80f9e Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@redhat.com>
Date: Thu, 31 May 2018 13:00:35 -0500
Subject: [PATCH] mon/OSDMonitor: mon_inject_pg_merge_bounce_probability

Optionally bounce pg_num back up right after we decrease it.  This triggers
conditions in the OSD where the merge and split logic may conflict.

Signed-off-by: Sage Weil <sage@redhat.com>
---
 src/common/options.cc |  4 ++++
 src/mon/OSDMonitor.cc | 16 +++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/common/options.cc b/src/common/options.cc
index 595497fc4269f..7973c63719ea5 100644
--- a/src/common/options.cc
+++ b/src/common/options.cc
@@ -1765,6 +1765,10 @@ std::vector<Option> get_global_options() {
     .set_default(0)
     .set_description(""),
 
+    Option("mon_inject_pg_merge_bounce_probability", Option::TYPE_FLOAT, Option::LEVEL_DEV)
+    .set_default(0)
+    .set_description(""),
+
     Option("mon_sync_provider_kill_at", Option::TYPE_INT, Option::LEVEL_DEV)
     .set_default(0)
     .set_description(""),
diff --git a/src/mon/OSDMonitor.cc b/src/mon/OSDMonitor.cc
index e9318a1bb237e..c30a18ee9e583 100644
--- a/src/mon/OSDMonitor.cc
+++ b/src/mon/OSDMonitor.cc
@@ -3288,7 +3288,21 @@ bool OSDMonitor::prepare_pg_ready_to_merge(MonOpRequestRef op)
 
   pending_inc.new_pools[m->pgid.pool()] = p;
 
-  wait_for_finished_proposal(op, new C_ReplyMap(this, op, m->version));
+  auto prob = g_conf().get_val<double>("mon_inject_pg_merge_bounce_probability");
+  if (prob > 0 && prob > (double)(rand() % 1000)/1000.0) {
+    derr << __func__ << " injecting pg merge pg_num bounce" << dendl;
+    auto n = new MMonCommand(mon->monmap->get_fsid());
+    n->set_connection(m->get_connection());
+    n->cmd = { "{\"prefix\":\"osd pool set\", \"pool\": \"" +
+	       osdmap.get_pool_name(m->pgid.pool()) +
+	       "\", \"var\": \"pg_num_actual\", \"val\": \"" +
+	       stringify(m->pgid.ps() + 1) + "\"}" };
+    MonOpRequestRef nop = mon->op_tracker.create_request<MonOpRequest>(n);
+    nop->set_type_service();
+    wait_for_finished_proposal(op, new C_RetryMessage(this, nop));
+  } else {
+    wait_for_finished_proposal(op, new C_ReplyMap(this, op, m->version));
+  }
   mon->no_reply(op);
   return true;
 }
-- 
2.39.5