mon/OSDMonitor: make pgp_num track pg_num more consistently

Previously we were automatically adjusting pgp_num_target on a
pg_num_target change *only* when decreasing pg_num.  Instead, make
pgp_num (continue to) track pg_num if it currently matches.  If it ever
is set differently than pg_num, leave it different (unless/until it
matches again).

This is still slightly weird, but I think in practice it is good enough.
In the rare case that the admin manually sets pgp_num to something
different than pg_num, they probably won't also be using automagic
pg_num adjustment that might make them match and start tracking again.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/mon/OSDMonitor.cc b/src/mon/OSDMonitor.cc
index 471855cf68eb3c3afabb6c9b5019ee95b89a71bb..9bb6f7e2bf4328286c63f6df6a43f17b89158f6f 100644 (file)
--- a/src/mon/OSDMonitor.cc
+++ b/src/mon/OSDMonitor.cc
@@ -6987,12 +6987,14 @@ int OSDMonitor::prepare_command_pool_set(const cmdmap_t& cmdmap,
        return -EPERM;
       }
     }
-    // set target; mgr will adjust pg_num_actual later
-    p.set_pg_num_target(n);
-    // adjust pgp_num_target down too (as needed)
-    if (p.get_pgp_num_target() > n) {
+    // set targets; mgr will adjust pg_num_actual and pgp_num later.
+    // make pgp_num track pg_num if it already matches.  if it is set
+    // differently, leave it different and let the user control it
+    // manually.
+    if (p.get_pg_num_target() == p.get_pgp_num_target()) {
       p.set_pgp_num_target(n);
     }
+    p.set_pg_num_target(n);
   } else if (var == "pgp_num_actual") {
     if (p.has_flag(pg_pool_t::FLAG_NOPGCHANGE)) {
       ss << "pool pgp_num change is disabled; you must unset nopgchange flag for the pool first";