MDS stuck in stopping with other rank's strays
Seen on a max_mds=2 MDS cluster with a fuse client doing an rsync -av --delete on a dir that included hard links.
Running a backup job overnight with two active MDS daemons, then I set max_mds=1 and deactivated rank 1 (client still mounted).
Log and cache dump attached from mds.gravel1 which held rank 1. It got most of the way through stopping and then got stuck with 6 items in cache, all things in ~mds0.
The log indicates that we're somehow not making it as far as trim_dentry on those items, but I can't see why.
Tried flushing journals, killing and evicting client, but no progress. Interestingly, when I tried setting mds_cache_size to 100 on rank 0, it also wouldn't trim past 500-something entries, so there was something going wrong with the trimming there too.