doc: add config help/get/set section for runtime client configuration

Fixes: http://tracker.ceph.com/issues/41688
Signed-off-by: Venky Shankar <vshankar@redhat.com>

diff --git a/doc/cephfs/client-config-ref.rst b/doc/cephfs/client-config-ref.rst
index 55820a4591e49c6bf589de7b8729c5defdf00311..e794a4a9c113672df334bed9e08ab8f697368ed8 100644 (file)
--- a/doc/cephfs/client-config-ref.rst
+++ b/doc/cephfs/client-config-ref.rst
@@ -1,6 +1,36 @@
-========================
- Client Config Reference
-========================
+Client Configuration
+====================
+
+Updating Client Configuration
+-----------------------------
+
+Certain client configurations can be applied at runtime. To check if a configuration option can be applied (taken into affect by a client) at runtime, use the `config help` command::
+
+   ceph config help debug_client
+    debug_client - Debug level for client
+    (str, advanced)                                                                                                                      Default: 0/5
+    Can update at runtime: true
+
+    The value takes the form 'N' or 'N/M' where N and M are values between 0 and 99.  N is the debug level to log (all values below this are included), and M is the level to gather and buffer in memory.  In the event of a crash, the most recent items <= M are dumped to the log file.
+
+`config help` tells if a given configuration can be applied at runtime along with the defaults and a description of the configuration option.
+
+To update a configuration option at runtime, use the `config set` command::
+
+   ceph config set client debug_client 20/20
+
+Note that this changes a given configuration for all clients.
+
+To check configured options use the `config get` command::
+
+   ceph config get client
+    WHO    MASK LEVEL    OPTION                    VALUE     RO 
+    client      advanced debug_client              20/20          
+    global      advanced osd_pool_default_min_size 1            
+    global      advanced osd_pool_default_size     3            
+
+Client Config Reference
+------------------------
 
 ``client acl type``