mgr/balancer: tolerate pgs outside of target weight map

We build a target weight map based on the primary crush weights, and
ignore weights that are 0.  However, it's possible that existing PGs are
on other OSDs that have weight 0 because the weight-set weight is >0.
That leads to a KeyError exception when we

                     pgs_by_osd[osd] += 1

and the key isn't present.  Fix by simply populating those keys as we
encounter OSDs.  Drop the old initialization loop.  The net of this is
we may have OSDs outside of target_by_root (won't matter, as far as I can
tell) and we won't have keys for osds with weight 0 (also won't matter,
as far as I can tell).

Fixes: https://tracker.ceph.com/issues/42721
Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/pybind/mgr/balancer/module.py b/src/pybind/mgr/balancer/module.py
index e70a7baee0f310763a664b6e14225af8d85a8b3e..36e0213f92e8c10f3f45f2225f2dcbf471d5370b 100644 (file)
--- a/src/pybind/mgr/balancer/module.py
+++ b/src/pybind/mgr/balancer/module.py
@@ -796,15 +796,14 @@ class Module(MgrModule):
             pgs_by_osd = {}
             objects_by_osd = {}
             bytes_by_osd = {}
-            for root in pe.pool_roots[pool]:
-                for osd in pe.target_by_root[root]:
-                    pgs_by_osd[osd] = 0
-                    objects_by_osd[osd] = 0
-                    bytes_by_osd[osd] = 0
             for pgid, up in six.iteritems(pm):
                 for osd in [int(osd) for osd in up]:
                     if osd == CRUSHMap.ITEM_NONE:
                         continue
+                    if osd not in pgs_by_osd:
+                        pgs_by_osd[osd] = 0
+                        objects_by_osd[osd] = 0
+                        bytes_by_osd[osd] = 0
                     pgs_by_osd[osd] += 1
                     objects_by_osd[osd] += ms.pg_stat[pgid]['num_objects']
                     bytes_by_osd[osd] += ms.pg_stat[pgid]['num_bytes']