rgw: Add documentation for RGW default quota

Fixes http://tracker.ceph.com/issues/16447
Cherry picked from e3ab347

This was modified to use size in kB, rather than size in bytes, since
Jewel has not yet been converted to use size in bytes.

Signed-off-by: Pavan Rallabhandi <PRallabhandi@walmartlabs.com>
Signed-off-by: Daniel Gryniewicz <dang@redhat.com>

doc/radosgw/admin.rst

@@ -400,6 +400,15 @@ To see how much of the quota a user has consumed, execute the following::
 .. note:: You should execute ``radosgw-admin user stats`` with the 
    ``--sync-stats`` option to receive the latest data.
 
+Default Quotas
+--------------
+
+You can set default quotas in the config.  These defaults are used when
+creating a new user and have no effect on existing users. If the
+relevant default quota is set in config, then that quota is set on the
+new user, and that quota is enabled.  See ``rgw bucket default quota max objects``,
+``rgw bucket default quota max size``, ``rgw user default quota max objects``, and
+``rgw user default quota max size`` in `Ceph Object Gateway Config Reference`_
 
 Reading / Writing Global Quotas
 -------------------------------
@@ -468,3 +477,4 @@ ranges for trim operations. ::
 
 .. _radosgw-admin: ../../man/8/radosgw-admin/
 .. _Pool Configuration: ../../rados/configuration/pool-pg-config-ref/
+.. _Ceph Object Gateway Config Reference: ../config-ref/

doc/radosgw/config-ref.rst

@@ -346,6 +346,40 @@ Ceph configuration file, the default value will be set automatically.
 :Type: Boolean
 :Default: ``false``
 
+
+``rgw bucket default quota max objects``
+
+:Description: Default max number of objects per bucket. Set on new users,
+              if no other quota is specified. Has no effect on existing users.
+:Type: Integer
+:Default: ``-1``
+
+
+``rgw bucket default quota max size``
+
+:Description: Default max capacity per bucket, in kB. Set on new users,
+              if no other quota is specified. Has no effect on existing users.
+:Type: Integer
+:Default: ``-1``
+
+
+``rgw user default quota max objects``
+
+:Description: Default max number of objects for a user. This includes all
+              objects in all buckets owned by the user. Set on new users,
+              if no other quota is specified. Has no effect on existing users.
+:Type: Integer
+:Default: ``-1``
+
+
+``rgw user default quota max size``
+
+:Description: The value for user max size quota in kB set on new users,
+              if no other quota is specified.  Has no effect on existing users.
+:Type: Integer
+:Default: ``-1``
+
+
 Regions
 =======