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Documentation / filesystems / nfs / nfs41-server.txt




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Based on kernel version 3.16. Page generated on 2014-08-06 21:39 EST.

1	NFSv4.1 Server Implementation
2	
3	Server support for minorversion 1 can be controlled using the
4	/proc/fs/nfsd/versions control file.  The string output returned
5	by reading this file will contain either "+4.1" or "-4.1"
6	correspondingly.
7	
8	Currently, server support for minorversion 1 is enabled by default.
9	It can be disabled at run time by writing the string "-4.1" to
10	the /proc/fs/nfsd/versions control file.  Note that to write this
11	control file, the nfsd service must be taken down.  You can use rpc.nfsd
12	for this; see rpc.nfsd(8).
13	
14	(Warning: older servers will interpret "+4.1" and "-4.1" as "+4" and
15	"-4", respectively.  Therefore, code meant to work on both new and old
16	kernels must turn 4.1 on or off *before* turning support for version 4
17	on or off; rpc.nfsd does this correctly.)
18	
19	The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
20	on RFC 5661.
21	
22	From the many new features in NFSv4.1 the current implementation
23	focuses on the mandatory-to-implement NFSv4.1 Sessions, providing
24	"exactly once" semantics and better control and throttling of the
25	resources allocated for each client.
26	
27	Other NFSv4.1 features, Parallel NFS operations in particular,
28	are still under development out of tree.
29	See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design
30	for more information.
31	
32	The table below, taken from the NFSv4.1 document, lists
33	the operations that are mandatory to implement (REQ), optional
34	(OPT), and NFSv4.0 operations that are required not to implement (MNI)
35	in minor version 1.  The first column indicates the operations that
36	are not supported yet by the linux server implementation.
37	
38	The OPTIONAL features identified and their abbreviations are as follows:
39		pNFS	Parallel NFS
40		FDELG	File Delegations
41		DDELG	Directory Delegations
42	
43	The following abbreviations indicate the linux server implementation status.
44		I	Implemented NFSv4.1 operations.
45		NS	Not Supported.
46		NS*	unimplemented optional feature.
47		P	pNFS features implemented out of tree.
48		PNS	pNFS features that are not supported yet (out of tree).
49	
50	Operations
51	
52	   +----------------------+------------+--------------+----------------+
53	   | Operation            | REQ, REC,  | Feature      | Definition     |
54	   |                      | OPT, or    | (REQ, REC,   |                |
55	   |                      | MNI        | or OPT)      |                |
56	   +----------------------+------------+--------------+----------------+
57	   | ACCESS               | REQ        |              | Section 18.1   |
58	I  | BACKCHANNEL_CTL      | REQ        |              | Section 18.33  |
59	I  | BIND_CONN_TO_SESSION | REQ        |              | Section 18.34  |
60	   | CLOSE                | REQ        |              | Section 18.2   |
61	   | COMMIT               | REQ        |              | Section 18.3   |
62	   | CREATE               | REQ        |              | Section 18.4   |
63	I  | CREATE_SESSION       | REQ        |              | Section 18.36  |
64	NS*| DELEGPURGE           | OPT        | FDELG (REQ)  | Section 18.5   |
65	   | DELEGRETURN          | OPT        | FDELG,       | Section 18.6   |
66	   |                      |            | DDELG, pNFS  |                |
67	   |                      |            | (REQ)        |                |
68	I  | DESTROY_CLIENTID     | REQ        |              | Section 18.50  |
69	I  | DESTROY_SESSION      | REQ        |              | Section 18.37  |
70	I  | EXCHANGE_ID          | REQ        |              | Section 18.35  |
71	I  | FREE_STATEID         | REQ        |              | Section 18.38  |
72	   | GETATTR              | REQ        |              | Section 18.7   |
73	P  | GETDEVICEINFO        | OPT        | pNFS (REQ)   | Section 18.40  |
74	P  | GETDEVICELIST        | OPT        | pNFS (OPT)   | Section 18.41  |
75	   | GETFH                | REQ        |              | Section 18.8   |
76	NS*| GET_DIR_DELEGATION   | OPT        | DDELG (REQ)  | Section 18.39  |
77	P  | LAYOUTCOMMIT         | OPT        | pNFS (REQ)   | Section 18.42  |
78	P  | LAYOUTGET            | OPT        | pNFS (REQ)   | Section 18.43  |
79	P  | LAYOUTRETURN         | OPT        | pNFS (REQ)   | Section 18.44  |
80	   | LINK                 | OPT        |              | Section 18.9   |
81	   | LOCK                 | REQ        |              | Section 18.10  |
82	   | LOCKT                | REQ        |              | Section 18.11  |
83	   | LOCKU                | REQ        |              | Section 18.12  |
84	   | LOOKUP               | REQ        |              | Section 18.13  |
85	   | LOOKUPP              | REQ        |              | Section 18.14  |
86	   | NVERIFY              | REQ        |              | Section 18.15  |
87	   | OPEN                 | REQ        |              | Section 18.16  |
88	NS*| OPENATTR             | OPT        |              | Section 18.17  |
89	   | OPEN_CONFIRM         | MNI        |              | N/A            |
90	   | OPEN_DOWNGRADE       | REQ        |              | Section 18.18  |
91	   | PUTFH                | REQ        |              | Section 18.19  |
92	   | PUTPUBFH             | REQ        |              | Section 18.20  |
93	   | PUTROOTFH            | REQ        |              | Section 18.21  |
94	   | READ                 | REQ        |              | Section 18.22  |
95	   | READDIR              | REQ        |              | Section 18.23  |
96	   | READLINK             | OPT        |              | Section 18.24  |
97	   | RECLAIM_COMPLETE     | REQ        |              | Section 18.51  |
98	   | RELEASE_LOCKOWNER    | MNI        |              | N/A            |
99	   | REMOVE               | REQ        |              | Section 18.25  |
100	   | RENAME               | REQ        |              | Section 18.26  |
101	   | RENEW                | MNI        |              | N/A            |
102	   | RESTOREFH            | REQ        |              | Section 18.27  |
103	   | SAVEFH               | REQ        |              | Section 18.28  |
104	   | SECINFO              | REQ        |              | Section 18.29  |
105	I  | SECINFO_NO_NAME      | REC        | pNFS files   | Section 18.45, |
106	   |                      |            | layout (REQ) | Section 13.12  |
107	I  | SEQUENCE             | REQ        |              | Section 18.46  |
108	   | SETATTR              | REQ        |              | Section 18.30  |
109	   | SETCLIENTID          | MNI        |              | N/A            |
110	   | SETCLIENTID_CONFIRM  | MNI        |              | N/A            |
111	NS | SET_SSV              | REQ        |              | Section 18.47  |
112	I  | TEST_STATEID         | REQ        |              | Section 18.48  |
113	   | VERIFY               | REQ        |              | Section 18.31  |
114	NS*| WANT_DELEGATION      | OPT        | FDELG (OPT)  | Section 18.49  |
115	   | WRITE                | REQ        |              | Section 18.32  |
116	
117	Callback Operations
118	
119	   +-------------------------+-----------+-------------+---------------+
120	   | Operation               | REQ, REC, | Feature     | Definition    |
121	   |                         | OPT, or   | (REQ, REC,  |               |
122	   |                         | MNI       | or OPT)     |               |
123	   +-------------------------+-----------+-------------+---------------+
124	   | CB_GETATTR              | OPT       | FDELG (REQ) | Section 20.1  |
125	P  | CB_LAYOUTRECALL         | OPT       | pNFS (REQ)  | Section 20.3  |
126	NS*| CB_NOTIFY               | OPT       | DDELG (REQ) | Section 20.4  |
127	P  | CB_NOTIFY_DEVICEID      | OPT       | pNFS (OPT)  | Section 20.12 |
128	NS*| CB_NOTIFY_LOCK          | OPT       |             | Section 20.11 |
129	NS*| CB_PUSH_DELEG           | OPT       | FDELG (OPT) | Section 20.5  |
130	   | CB_RECALL               | OPT       | FDELG,      | Section 20.2  |
131	   |                         |           | DDELG, pNFS |               |
132	   |                         |           | (REQ)       |               |
133	NS*| CB_RECALL_ANY           | OPT       | FDELG,      | Section 20.6  |
134	   |                         |           | DDELG, pNFS |               |
135	   |                         |           | (REQ)       |               |
136	NS | CB_RECALL_SLOT          | REQ       |             | Section 20.8  |
137	NS*| CB_RECALLABLE_OBJ_AVAIL | OPT       | DDELG, pNFS | Section 20.7  |
138	   |                         |           | (REQ)       |               |
139	I  | CB_SEQUENCE             | OPT       | FDELG,      | Section 20.9  |
140	   |                         |           | DDELG, pNFS |               |
141	   |                         |           | (REQ)       |               |
142	NS*| CB_WANTS_CANCELLED      | OPT       | FDELG,      | Section 20.10 |
143	   |                         |           | DDELG, pNFS |               |
144	   |                         |           | (REQ)       |               |
145	   +-------------------------+-----------+-------------+---------------+
146	
147	Implementation notes:
148	
149	SSV:
150	* The spec claims this is mandatory, but we don't actually know of any
151	  implementations, so we're ignoring it for now.  The server returns
152	  NFS4ERR_ENCR_ALG_UNSUPP on EXCHANGE_ID, which should be future-proof.
153	
154	GSS on the backchannel:
155	* Again, theoretically required but not widely implemented (in
156	  particular, the current Linux client doesn't request it).  We return
157	  NFS4ERR_ENCR_ALG_UNSUPP on CREATE_SESSION.
158	
159	DELEGPURGE:
160	* mandatory only for servers that support CLAIM_DELEGATE_PREV and/or
161	  CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that
162	  persist across client reboots).  Thus we need not implement this for
163	  now.
164	
165	EXCHANGE_ID:
166	* implementation ids are ignored
167	
168	CREATE_SESSION:
169	* backchannel attributes are ignored
170	
171	SEQUENCE:
172	* no support for dynamic slot table renegotiation (optional)
173	
174	Nonstandard compound limitations:
175	* No support for a sessions fore channel RPC compound that requires both a
176	  ca_maxrequestsize request and a ca_maxresponsesize reply, so we may
177	  fail to live up to the promise we made in CREATE_SESSION fore channel
178	  negotiation.
179	
180	See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues.
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