[FTS] Indexing stuck when disk is full, cpu usage is ~100%

Build
4.5.0-1720

Perf sanity test:
./testrunner -i INI_FILE.ini -t fts.stable_topology_fts.StableTopFTS.test_query_type,items=1000000,num_queries=100,query_types=match,match_phrase,dataset=wiki,cluster=D+F,F,index_retry=20,get-cbcollect-info=True,query_max_matches=10000

The test tries indexing 1M wiki docs and querying it. Cluster: D+F:F (2 node cluster, 2 nodes with fts)

Indexing is stuck at 80.56% for more than 5 mins. Test enters query phase where all queries time out.

Test log : https://gist.github.com/arunapiravi/8e0ae6edd63de5356dfc
Live cluster : http://172.23.123.38:8091/ui/index.html

This could be related to moss but I need the cluster back to verify the no-moss case.

Attaching logs from both nodes.