Ceph » CephFS

We use two active MDS in our online environment, recently mds.1 restarted and during its rejoin phase, mds.0 met assert failure when processing the weak rejoin request from mds.1, below is the log snip:

2> 2018-01-04 20:50:50.638943 7f9fb9cfb700 5 mds.mmcommcephsz11 handle_mds_map epoch 694747 from mds.1
-1> 2018-01-04 20:50:50.638952 7f9fb9cfb700 5 mds.mmcommcephsz11 old map epoch 694747 <= 694747, discarding
0> 2018-01-04 20:50:50.652715 7f9fb9cfb700 -1 mds/MDCache.cc: In function 'void MDCache::handle_cache_rejoin_weak(MMDSCacheRejoin*)' thread 7f9fb9cfb700 time 2018-01-04 20:50:50.650286
mds/MDCache.cc: 4325: FAILED assert(in && in>is_auth())

ceph version 10.2.9-102-g820619c (820619cc59a3790ab36be1945a135eb826c558f1)
 1: (ceph::__ceph_assert_fail(char const*, char const*, int, char const*)+0x85) [0x7f9fc0981205]
 2: (MDCache::handle_cache_rejoin_weak(MMDSCacheRejoin*)+0x63e) [0x7f9fc068759e]
 3: (MDCache::handle_cache_rejoin(MMDSCacheRejoin*)+0x25b) [0x7f9fc068d04b]
 4: (MDCache::dispatch(Message*)+0xa5) [0x7f9fc069d975]
 5: (MDSRank::handle_deferrable_message(Message*)+0x5ef) [0x7f9fc058792f]
 6: (MDSRank::_dispatch(Message*, bool)+0x1e0) [0x7f9fc0592250]
 7: (MDSRankDispatcher::ms_dispatch(Message*)+0x15) [0x7f9fc05933e5]
 8: (MDSDaemon::ms_dispatch(Message*)+0xf3) [0x7f9fc0578a03]
 9: (Messenger::ms_deliver_dispatch(Message*)+0x77) [0x7f9fc0af2017]
 10: (C_handle_dispatch::do_request(int)+0x11) [0x7f9fc0af2761]
 11: (EventCenter::process_events(int)+0x90a) [0x7f9fc0a92aba]
 12: (Worker::entry()+0x1f0) [0x7f9fc0a68170]
 13: (()+0x7dc5) [0x7f9fbf755dc5]
 14: (clone()+0x6d) [0x7f9fbe22129d]

After checking the related code, it seems that the assert(in && in->is_auth()) is too strict, because the inode for this cap_export maybe expired from Cache, and change the assert into assert(!in || in->is_auth) is more reasonable.