-Command 101: LDLM ENQUEUE - Enqueue a lock request
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+RPC 101: LDLM ENQUEUE - Enqueue a lock request
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[[ldlm-enqueue-rpc]]
An RPC that implements distributed locking across the servers and
'ldlm_reply' descriptors of the desired and granted locks.
.LDLM_ENQUEUE Generic Packet Structure
-image::ldlm-enqueue-generic.png["LDLM_ENQUEUE Generic Packet Structure",height=150]
+image::ldlm-enqueue-generic.png["LDLM_ENQUEUE Generic Packet Structure",height=100]
//////////////////////////////////////////////////////////////////////
The ldlm-enqueue-generic.png diagram resembles this text
--reply---------------------
| ptlrpc_body | ldlm_reply |
----------------------------
- --extent lvb reply--------------------
- | ptlrpc_body | ldlm_reply | ost_lvb |
- --------------------------------------
//////////////////////////////////////////////////////////////////////
However, there are many variants to this RPCs. A lock request may signal
-----------------------------------------
//////////////////////////////////////////////////////////////////////
+And in this example the intent is to get attribute information.
+
+.LDLM_ENQUEUE Intent:Getattr Generic Packet Structure
+image::ldlm-enqueue-intent-getattr-generic.png["LDLM_ENQUEUE Intent:Getattr Generic Packet Structure",height=150]
+
+//////////////////////////////////////////////////////////////////////
+The ldlm-enqueue-intent-getattr-generic.png diagram resembles this text
+art:
+
+ LDLM_ENQUEUE:
+ --intent:getattr request-------------------------------
+ | ptlrpc_body | ldlm_request | ldlm_intent | mdt_body |
+ lustre_capa |name |
+ -------------------------------------------------------
+ --intent:getattr reply--------------------------
+ | ptlrpc_body | ldlm_reply | mdt_body | mdt_md |
+ ------------------------------------------------
+ --intent:lvb reply--------------------
+ | ptlrpc_body | ldlm_reply | ost_lvb |
+ --------------------------------------
+//////////////////////////////////////////////////////////////////////
+
+Here is another example of an intent, in this case the 'getxattr' intent.
+
+.LDLM_ENQUEUE Intent:Getxattr Generic Packet Structure
+image::ldlm-enqueue-intent-getxattr-generic.png["LDLM_ENQUEUE Intent:Getxattr Generic Packet Structure",height=125]
+
+//////////////////////////////////////////////////////////////////////
+The ldlm-enqueue-intent-getxattr-generic.png diagram resembles this text
+art:
+
+ LDLM_ENQUEUE:
+ --intent:getxattr request------------------------------------
+ | ptlrpc_body | ldlm_request |ldlm_intent | mdt_body | capa |
+ -------------------------------------------------------------
+ --intent:getxattr reply----------------------------------------
+ | ptlrpc_body | ldlm_reply | mdt_body | lov_mds_md | ACL data |
+ | EA data | EA vals | EA lens |
+ ---------------------------------------------------------------
+//////////////////////////////////////////////////////////////////////
+
'ptlrpc_body'::
-RPC descriptor.
+RPC descriptor <<struct-ptlrpc-body>>.
+
+include::struct_ldlm_request.txt[]
+
+include::struct_ldlm_intent.txt[]
-'ldlm_request'::
-Description of the lock being requested. Which resource is the target,
-what lock is current, and what lock desired.
+include::struct_layout_intent.txt[]
-'ldlm_intent'::
-Description of the intent being included with the lock request.
+'mdt_body'::
+In a request, an indication (in the 'mbo_valid' field) of what
+attributes the requester would like. In a reply, (again based on
+'mbo_valid') the values being returned. <<struct-mdt-body>>
-'layout_intent'::
-Description of the layout information that is the subject of a layout
-intent.
+'lustre_capa'::
+So called "capabilities" structure. This is deprecated in recent
+versions of Lustre, and commonly appears in the packet header as a zero
+length buffer.
-'ldlm_reply'::
-Resembling the 'ldlm_request', but in this case indicating what the
-LDLM actually granted as well as relevant policy data.
+'name'::
+A text field supplying the name of the desired resource.
+
+include::struct_ldlm_reply.txt[]
+
+'ACL data'::
+Access Control List data associated with a resource.
+
+'EA data'::
+The names of any extended attributes associated with the resource. The
+names are null-terminated strings concatenated into a single sequnce.
+
+'EA vals'::
+A block of data concatenating the values for the extended attributes
+listed in "EA vals".
+
+'EA lens'::
+The sizes of the extended attirbute values. This is a sequence of
+32-bit unsigned integers, one for each extended
+attribute. The sizes give the length of the corresponding extended
+attribute in the "EA vals" block of data. Thus the sum of those sizes
+equals the length of the "EA vals".
Lock Value Block::
A Lock Value Block (LVB) is included in the LDLM_ENQUEUE reply message
when one of three things needs to be communicated back to the
requester. The three alternatives are captured by the
-'ost_lvb'structure, the 'lov_mds_md' structure, and one other related
+'ost_lvb' structure, the 'lov_mds_md' structure, and one other related
to quotas (and not yet incorporated into this document). LDLM_ENQUEUE
reply RPCs may include a zero length instance of an LVB.
-'ost_lvb'::
-An LVB to communicate attribute data for an extent associated with a
-resource on a lock. It is returned from an OST to a client requesting
-an extent lock.
-
-'lov_mds_md'::
-An LVB to communicate layout data associated with a resource. It is
-returned from an MDT to a client requesting a lock a lock with a
-layout intent. In an intent request (as opposed to a reply and as yet
-unimplemanted) it will modify the layout. It will not be included
-(zero length) in requests in current releases.
+include::struct_ost_lvb.txt[]
+
+include::struct_lov_mds_md.txt[]
+
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