Data race(s) seen during bcache shutdown

WARNING: ThreadSanitizer: data race (pid=16606)

  Write of size 8 at 0x7d100020c0a8 by thread T2 (mutexes: write M10, write M15):

    #0 list_remove /home/abhinav/couchbaseTS/forestdb/src/list.cc:89 (fdb_functional_test+0x000000624716)

    #1 bcache_shutdown /home/abhinav/couchbaseTS/forestdb/src/blockcache.cc:1605 (fdb_functional_test+0x00000050dc8f)

    #2 filemgr_shutdown /home/abhinav/couchbaseTS/forestdb/src/filemgr.cc:1758 (fdb_functional_test+0x0000005769ff)

    #3 fdb_shutdown /home/abhinav/couchbaseTS/forestdb/src/forestdb.cc:7851 (fdb_functional_test+0x0000005c69a0)

    #4 multi_thread_client_shutdown(void*) /home/abhinav/couchbaseTS/forestdb/tests/functional/fdb_functional_test.cc:2011 (fdb_functional_test+0x0000004d81f1)

  Previous write of size 8 at 0x7d100020c0a8 by thread T1 (mutexes: write M23078079052191248, write M17):

    #0 list_push_front /home/abhinav/couchbaseTS/forestdb/src/list.cc:34 (fdb_functional_test+0x000000623dfe)

    #1 _bcache_release_freeblock(bcache_item*) /home/abhinav/couchbaseTS/forestdb/src/blockcache.cc:315 (fdb_functional_test+0x000000505972)

    #2 bcache_remove_clean_blocks /home/abhinav/couchbaseTS/forestdb/src/blockcache.cc:1324 (fdb_functional_test+0x00000050b627)

    #3 filemgr_free_func /home/abhinav/couchbaseTS/forestdb/src/filemgr.cc:1614 (fdb_functional_test+0x00000056ad37)

    #4 filemgr_close /home/abhinav/couchbaseTS/forestdb/src/filemgr.cc:1567 (fdb_functional_test+0x00000057568b)

    #5 _fdb_close /home/abhinav/couchbaseTS/forestdb/src/forestdb.cc:7299 (fdb_functional_test+0x0000005a309a)

    #6 _fdb_close_root /home/abhinav/couchbaseTS/forestdb/src/forestdb.cc:7270 (fdb_functional_test+0x0000005a197c)

    #7 fdb_close /home/abhinav/couchbaseTS/forestdb/src/forestdb.cc:7228 (fdb_functional_test+0x0000005c2d2f)

    #8 multi_thread_client_shutdown(void*) /home/abhinav/couchbaseTS/forestdb/tests/functional/fdb_functional_test.cc:2008 (fdb_functional_test+0x0000004d8132)

WARNING: ThreadSanitizer: data race (pid=3464)

  Write of size 8 at 0x7db000000000 by thread T2 (mutexes: write M10, write M15):

    #0 free <null> (fdb_functional_test+0x000000456f1b)

    #1 bcache_shutdown /home/abhinav/couchbaseTS/forestdb/src/blockcache.cc:1620 (fdb_functional_test+0x0000004de9d6)

    #2 filemgr_shutdown /home/abhinav/couchbaseTS/forestdb/src/filemgr.cc:1758 (fdb_functional_test+0x0000004f989b)

    #3 fdb_shutdown /home/abhinav/couchbaseTS/forestdb/src/forestdb.cc:7851 (fdb_functional_test+0x0000005152af)

    #4 multi_thread_client_shutdown(void*) /home/abhinav/couchbaseTS/forestdb/tests/functional/fdb_functional_test.cc:2011 (fdb_functional_test+0x0000004c87be)

  Previous write of size 8 at 0x7db000000000 by thread T1 (mutexes: write M18):

    #0 _fname_try_free(fnamedic_item*) /home/abhinav/couchbaseTS/forestdb/src/blockcache.cc:852 (fdb_functional_test+0x0000004ddccb)

    #1 filemgr_free_func /home/abhinav/couchbaseTS/forestdb/src/filemgr.cc:1615 (fdb_functional_test+0x0000004f676f)

    #2 filemgr_close /home/abhinav/couchbaseTS/forestdb/src/filemgr.cc:1567 (fdb_functional_test+0x0000004f927b)

    #3 _fdb_close /home/abhinav/couchbaseTS/forestdb/src/forestdb.cc:7299 (fdb_functional_test+0x000000506bcb)

    #4 _fdb_close_root /home/abhinav/couchbaseTS/forestdb/src/forestdb.cc:7270 (fdb_functional_test+0x000000506070)

    #5 fdb_close /home/abhinav/couchbaseTS/forestdb/src/forestdb.cc:7228 (fdb_functional_test+0x000000513a5a)

    #6 multi_thread_client_shutdown(void*) /home/abhinav/couchbaseTS/forestdb/tests/functional/fdb_functional_test.cc:2008 (fdb_functional_test+0x0000004c8767)