mon: fix divide by zero when pg_num adjusted and no osds

Fixes: #9101
Backport: firefly, dumpling
Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/mon/OSDMonitor.cc b/src/mon/OSDMonitor.cc
index e5e46e937a1bc31dbdedb4b48eb46f35cbda9634..ade6081f68d110b82a85666ec56ca5791ae45f7b 100644 (file)
--- a/src/mon/OSDMonitor.cc
+++ b/src/mon/OSDMonitor.cc
@@ -3598,7 +3598,7 @@ int OSDMonitor::prepare_command_pool_set(map<string,cmd_vartype> &cmdmap,
       ss << "splits in cache pools must be followed by scrubs and leave sufficient free space to avoid overfilling.  use --yes-i-really-mean-it to force.";
       return -EPERM;
     }
-    int expected_osds = MIN(p.get_pg_num(), osdmap.get_num_osds());
+    int expected_osds = MAX(1, MIN(p.get_pg_num(), osdmap.get_num_osds()));
     int64_t new_pgs = n - p.get_pg_num();
     int64_t pgs_per_osd = new_pgs / expected_osds;
     if (pgs_per_osd > g_conf->mon_osd_max_split_count) {