[james-page, r=gnuoy] Add configuration option for toggling use of direct io for OSD journals

config.yaml

@@ -152,3 +152,8 @@ options:
     description: |
       A comma-separated list of nagios servicegroups.
       If left empty, the nagios_context will be used as the servicegroup
+  use-direct-io:
+    default: True
+    type: boolean
+    description: Configure use of direct IO for OSD journals.
+

hooks/ceph_hooks.py

@@ -86,6 +86,7 @@ def emit_cephconf():
         'ceph_public_network': config('ceph-public-network'),
         'ceph_cluster_network': config('ceph-cluster-network'),
         'loglevel': config('loglevel'),
+        'dio': str(config('use-direct-io')).lower(),
     }
 
     if config('prefer-ipv6'):

templates/ceph.conf

@@ -40,4 +40,5 @@ keyring = /var/lib/ceph/mds/$cluster-$id/keyring
 keyring = /var/lib/ceph/osd/$cluster-$id/keyring
 osd journal size = {{ osd_journal_size }}
 filestore xattr use omap = true
+journal dio = {{ dio }}