LUDOC-276 protocol: Document RPCs for setattr

[doc/protocol.git] / ldlm_cp_callback.txt

diff --git a/ldlm_cp_callback.txt b/ldlm_cp_callback.txt
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+Command 105: LDLM_CP_CALLBACK
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+[[ldlm-cp-callback-rpc]]
+
+An RPC that notifies an entity that a requested lock is now available.
+
+.LDLM_CP_CALLBACK Generic Packet Structure
+image::ldlm-cp-callback-generic.png["LDLM_CP_CALLBACK Generic Packet Structure",height=100]
+
+//////////////////////////////////////////////////////////////////////
+The ldlm-cp-callback-generic.png diagram resembles this text
+art:
+
+       LDLM_CP_CALLBACK:
+      --request-------------------------------
+      | ptlrpc_body | ldlm_request | ost_lvb |
+      ----------------------------------------
+      --reply--------
+      | ptlrpc_body |
+      ---------------
+//////////////////////////////////////////////////////////////////////
+
+The request RPC identifies the relevant resource that already had a
+request pending. It notifies the original requester that it now has
+the stated lock, along with attribute information the about the
+resource. The reply is just an acknowledgment of receipt, and doesn't
+carry any further information about the lock or the resource.
+
+'ptlrpc_body'::
+RPC descriptor.
+
+'ldlm_request'::
+Description of the lock being requested. Which resource is the target,
+what lock is current, and what lock desired.
+
+'ost_lvb'::
+Attribute data associated with a resource on an OST.
+