1=============================
2NFSv4.1 Server Implementation
3=============================
4
5Server support for minorversion 1 can be controlled using the
6/proc/fs/nfsd/versions control file.  The string output returned
7by reading this file will contain either "+4.1" or "-4.1"
8correspondingly.
9
10Currently, server support for minorversion 1 is enabled by default.
11It can be disabled at run time by writing the string "-4.1" to
12the /proc/fs/nfsd/versions control file.  Note that to write this
13control file, the nfsd service must be taken down.  You can use rpc.nfsd
14for this; see rpc.nfsd(8).
15
16(Warning: older servers will interpret "+4.1" and "-4.1" as "+4" and
17"-4", respectively.  Therefore, code meant to work on both new and old
18kernels must turn 4.1 on or off *before* turning support for version 4
19on or off; rpc.nfsd does this correctly.)
20
21The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
22on RFC 5661.
23
24From the many new features in NFSv4.1 the current implementation
25focuses on the mandatory-to-implement NFSv4.1 Sessions, providing
26"exactly once" semantics and better control and throttling of the
27resources allocated for each client.
28
29The table below, taken from the NFSv4.1 document, lists
30the operations that are mandatory to implement (REQ), optional
31(OPT), and NFSv4.0 operations that are required not to implement (MNI)
32in minor version 1.  The first column indicates the operations that
33are not supported yet by the linux server implementation.
34
35The OPTIONAL features identified and their abbreviations are as follows:
36
37- **pNFS**	Parallel NFS
38- **FDELG**	File Delegations
39- **DDELG**	Directory Delegations
40
41The following abbreviations indicate the linux server implementation status.
42
43- **I**	Implemented NFSv4.1 operations.
44- **NS**	Not Supported.
45- **NS\***	Unimplemented optional feature.
46
47Operations
48==========
49
50+-----------------------+----------------------+---------------------+---------------------------+----------------+
51| Implementation status | Operation            | REQ,REC, OPT or NMI | Feature (REQ, REC or OPT) | Definition     |
52+=======================+======================+=====================+===========================+================+
53|                       | ACCESS               | REQ                 |                           | Section 18.1   |
54+-----------------------+----------------------+---------------------+---------------------------+----------------+
55| I                     | BACKCHANNEL_CTL      | REQ                 |                           | Section 18.33  |
56+-----------------------+----------------------+---------------------+---------------------------+----------------+
57| I                     | BIND_CONN_TO_SESSION | REQ                 |                           | Section 18.34  |
58+-----------------------+----------------------+---------------------+---------------------------+----------------+
59|                       | CLOSE                | REQ                 |                           | Section 18.2   |
60+-----------------------+----------------------+---------------------+---------------------------+----------------+
61|                       | COMMIT               | REQ                 |                           | Section 18.3   |
62+-----------------------+----------------------+---------------------+---------------------------+----------------+
63|                       | CREATE               | REQ                 |                           | Section 18.4   |
64+-----------------------+----------------------+---------------------+---------------------------+----------------+
65| I                     | CREATE_SESSION       | REQ                 |                           | Section 18.36  |
66+-----------------------+----------------------+---------------------+---------------------------+----------------+
67| NS*                   | DELEGPURGE           | OPT                 | FDELG (REQ)               | Section 18.5   |
68+-----------------------+----------------------+---------------------+---------------------------+----------------+
69|                       | DELEGRETURN          | OPT                 | FDELG,                    | Section 18.6   |
70+-----------------------+----------------------+---------------------+---------------------------+----------------+
71|                       |                      |                     | DDELG, pNFS               |                |
72+-----------------------+----------------------+---------------------+---------------------------+----------------+
73|                       |                      |                     | (REQ)                     |                |
74+-----------------------+----------------------+---------------------+---------------------------+----------------+
75| I                     | DESTROY_CLIENTID     | REQ                 |                           | Section 18.50  |
76+-----------------------+----------------------+---------------------+---------------------------+----------------+
77| I                     | DESTROY_SESSION      | REQ                 |                           | Section 18.37  |
78+-----------------------+----------------------+---------------------+---------------------------+----------------+
79| I                     | EXCHANGE_ID          | REQ                 |                           | Section 18.35  |
80+-----------------------+----------------------+---------------------+---------------------------+----------------+
81| I                     | FREE_STATEID         | REQ                 |                           | Section 18.38  |
82+-----------------------+----------------------+---------------------+---------------------------+----------------+
83|                       | GETATTR              | REQ                 |                           | Section 18.7   |
84+-----------------------+----------------------+---------------------+---------------------------+----------------+
85| I                     | GETDEVICEINFO        | OPT                 | pNFS (REQ)                | Section 18.40  |
86+-----------------------+----------------------+---------------------+---------------------------+----------------+
87| NS*                   | GETDEVICELIST        | OPT                 | pNFS (OPT)                | Section 18.41  |
88+-----------------------+----------------------+---------------------+---------------------------+----------------+
89|                       | GETFH                | REQ                 |                           | Section 18.8   |
90+-----------------------+----------------------+---------------------+---------------------------+----------------+
91| NS*                   | GET_DIR_DELEGATION   | OPT                 | DDELG (REQ)               | Section 18.39  |
92+-----------------------+----------------------+---------------------+---------------------------+----------------+
93| I                     | LAYOUTCOMMIT         | OPT                 | pNFS (REQ)                | Section 18.42  |
94+-----------------------+----------------------+---------------------+---------------------------+----------------+
95| I                     | LAYOUTGET            | OPT                 | pNFS (REQ)                | Section 18.43  |
96+-----------------------+----------------------+---------------------+---------------------------+----------------+
97| I                     | LAYOUTRETURN         | OPT                 | pNFS (REQ)                | Section 18.44  |
98+-----------------------+----------------------+---------------------+---------------------------+----------------+
99|                       | LINK                 | OPT                 |                           | Section 18.9   |
100+-----------------------+----------------------+---------------------+---------------------------+----------------+
101|                       | LOCK                 | REQ                 |                           | Section 18.10  |
102+-----------------------+----------------------+---------------------+---------------------------+----------------+
103|                       | LOCKT                | REQ                 |                           | Section 18.11  |
104+-----------------------+----------------------+---------------------+---------------------------+----------------+
105|                       | LOCKU                | REQ                 |                           | Section 18.12  |
106+-----------------------+----------------------+---------------------+---------------------------+----------------+
107|                       | LOOKUP               | REQ                 |                           | Section 18.13  |
108+-----------------------+----------------------+---------------------+---------------------------+----------------+
109|                       | LOOKUPP              | REQ                 |                           | Section 18.14  |
110+-----------------------+----------------------+---------------------+---------------------------+----------------+
111|                       | NVERIFY              | REQ                 |                           | Section 18.15  |
112+-----------------------+----------------------+---------------------+---------------------------+----------------+
113|                       | OPEN                 | REQ                 |                           | Section 18.16  |
114+-----------------------+----------------------+---------------------+---------------------------+----------------+
115| NS*                   | OPENATTR             | OPT                 |                           | Section 18.17  |
116+-----------------------+----------------------+---------------------+---------------------------+----------------+
117|                       | OPEN_CONFIRM         | MNI                 |                           | N/A            |
118+-----------------------+----------------------+---------------------+---------------------------+----------------+
119|                       | OPEN_DOWNGRADE       | REQ                 |                           | Section 18.18  |
120+-----------------------+----------------------+---------------------+---------------------------+----------------+
121|                       | PUTFH                | REQ                 |                           | Section 18.19  |
122+-----------------------+----------------------+---------------------+---------------------------+----------------+
123|                       | PUTPUBFH             | REQ                 |                           | Section 18.20  |
124+-----------------------+----------------------+---------------------+---------------------------+----------------+
125|                       | PUTROOTFH            | REQ                 |                           | Section 18.21  |
126+-----------------------+----------------------+---------------------+---------------------------+----------------+
127|                       | READ                 | REQ                 |                           | Section 18.22  |
128+-----------------------+----------------------+---------------------+---------------------------+----------------+
129|                       | READDIR              | REQ                 |                           | Section 18.23  |
130+-----------------------+----------------------+---------------------+---------------------------+----------------+
131|                       | READLINK             | OPT                 |                           | Section 18.24  |
132+-----------------------+----------------------+---------------------+---------------------------+----------------+
133|                       | RECLAIM_COMPLETE     | REQ                 |                           | Section 18.51  |
134+-----------------------+----------------------+---------------------+---------------------------+----------------+
135|                       | RELEASE_LOCKOWNER    | MNI                 |                           | N/A            |
136+-----------------------+----------------------+---------------------+---------------------------+----------------+
137|                       | REMOVE               | REQ                 |                           | Section 18.25  |
138+-----------------------+----------------------+---------------------+---------------------------+----------------+
139|                       | RENAME               | REQ                 |                           | Section 18.26  |
140+-----------------------+----------------------+---------------------+---------------------------+----------------+
141|                       | RENEW                | MNI                 |                           | N/A            |
142+-----------------------+----------------------+---------------------+---------------------------+----------------+
143|                       | RESTOREFH            | REQ                 |                           | Section 18.27  |
144+-----------------------+----------------------+---------------------+---------------------------+----------------+
145|                       | SAVEFH               | REQ                 |                           | Section 18.28  |
146+-----------------------+----------------------+---------------------+---------------------------+----------------+
147|                       | SECINFO              | REQ                 |                           | Section 18.29  |
148+-----------------------+----------------------+---------------------+---------------------------+----------------+
149| I                     | SECINFO_NO_NAME      | REC                 | pNFS files                | Section 18.45, |
150+-----------------------+----------------------+---------------------+---------------------------+----------------+
151|                       |                      |                     | layout (REQ)              | Section 13.12  |
152+-----------------------+----------------------+---------------------+---------------------------+----------------+
153| I                     | SEQUENCE             | REQ                 |                           | Section 18.46  |
154+-----------------------+----------------------+---------------------+---------------------------+----------------+
155|                       | SETATTR              | REQ                 |                           | Section 18.30  |
156+-----------------------+----------------------+---------------------+---------------------------+----------------+
157|                       | SETCLIENTID          | MNI                 |                           | N/A            |
158+-----------------------+----------------------+---------------------+---------------------------+----------------+
159|                       | SETCLIENTID_CONFIRM  | MNI                 |                           | N/A            |
160+-----------------------+----------------------+---------------------+---------------------------+----------------+
161| NS                    | SET_SSV              | REQ                 |                           | Section 18.47  |
162+-----------------------+----------------------+---------------------+---------------------------+----------------+
163| I                     | TEST_STATEID         | REQ                 |                           | Section 18.48  |
164+-----------------------+----------------------+---------------------+---------------------------+----------------+
165|                       | VERIFY               | REQ                 |                           | Section 18.31  |
166+-----------------------+----------------------+---------------------+---------------------------+----------------+
167| NS*                   | WANT_DELEGATION      | OPT                 | FDELG (OPT)               | Section 18.49  |
168+-----------------------+----------------------+---------------------+---------------------------+----------------+
169|                       | WRITE                | REQ                 |                           | Section 18.32  |
170+-----------------------+----------------------+---------------------+---------------------------+----------------+
171
172
173Callback Operations
174===================
175+-----------------------+-------------------------+---------------------+---------------------------+---------------+
176| Implementation status | Operation               | REQ,REC, OPT or NMI | Feature (REQ, REC or OPT) | Definition    |
177+=======================+=========================+=====================+===========================+===============+
178|                       | CB_GETATTR              | OPT                 | FDELG (REQ)               | Section 20.1  |
179+-----------------------+-------------------------+---------------------+---------------------------+---------------+
180| I                     | CB_LAYOUTRECALL         | OPT                 | pNFS (REQ)                | Section 20.3  |
181+-----------------------+-------------------------+---------------------+---------------------------+---------------+
182| NS*                   | CB_NOTIFY               | OPT                 | DDELG (REQ)               | Section 20.4  |
183+-----------------------+-------------------------+---------------------+---------------------------+---------------+
184| NS*                   | CB_NOTIFY_DEVICEID      | OPT                 | pNFS (OPT)                | Section 20.12 |
185+-----------------------+-------------------------+---------------------+---------------------------+---------------+
186| NS*                   | CB_NOTIFY_LOCK          | OPT                 |                           | Section 20.11 |
187+-----------------------+-------------------------+---------------------+---------------------------+---------------+
188| NS*                   | CB_PUSH_DELEG           | OPT                 | FDELG (OPT)               | Section 20.5  |
189+-----------------------+-------------------------+---------------------+---------------------------+---------------+
190|                       | CB_RECALL               | OPT                 | FDELG,                    | Section 20.2  |
191+-----------------------+-------------------------+---------------------+---------------------------+---------------+
192|                       |                         |                     | DDELG, pNFS               |               |
193+-----------------------+-------------------------+---------------------+---------------------------+---------------+
194|                       |                         |                     | (REQ)                     |               |
195+-----------------------+-------------------------+---------------------+---------------------------+---------------+
196| NS*                   | CB_RECALL_ANY           | OPT                 | FDELG,                    | Section 20.6  |
197+-----------------------+-------------------------+---------------------+---------------------------+---------------+
198|                       |                         |                     | DDELG, pNFS               |               |
199+-----------------------+-------------------------+---------------------+---------------------------+---------------+
200|                       |                         |                     | (REQ)                     |               |
201+-----------------------+-------------------------+---------------------+---------------------------+---------------+
202| NS                    | CB_RECALL_SLOT          | REQ                 |                           | Section 20.8  |
203+-----------------------+-------------------------+---------------------+---------------------------+---------------+
204| NS*                   | CB_RECALLABLE_OBJ_AVAIL | OPT                 | DDELG, pNFS               | Section 20.7  |
205+-----------------------+-------------------------+---------------------+---------------------------+---------------+
206|                       |                         |                     | (REQ)                     |               |
207+-----------------------+-------------------------+---------------------+---------------------------+---------------+
208| I                     | CB_SEQUENCE             | OPT                 | FDELG,                    | Section 20.9  |
209+-----------------------+-------------------------+---------------------+---------------------------+---------------+
210|                       |                         |                     | DDELG, pNFS               |               |
211+-----------------------+-------------------------+---------------------+---------------------------+---------------+
212|                       |                         |                     | (REQ)                     |               |
213+-----------------------+-------------------------+---------------------+---------------------------+---------------+
214| NS*                   | CB_WANTS_CANCELLED      | OPT                 | FDELG,                    | Section 20.10 |
215+-----------------------+-------------------------+---------------------+---------------------------+---------------+
216|                       |                         |                     | DDELG, pNFS               |               |
217+-----------------------+-------------------------+---------------------+---------------------------+---------------+
218|                       |                         |                     | (REQ)                     |               |
219+-----------------------+-------------------------+---------------------+---------------------------+---------------+
220
221
222Implementation notes:
223=====================
224
225SSV:
226  The spec claims this is mandatory, but we don't actually know of any
227  implementations, so we're ignoring it for now.  The server returns
228  NFS4ERR_ENCR_ALG_UNSUPP on EXCHANGE_ID, which should be future-proof.
229
230GSS on the backchannel:
231  Again, theoretically required but not widely implemented (in
232  particular, the current Linux client doesn't request it).  We return
233  NFS4ERR_ENCR_ALG_UNSUPP on CREATE_SESSION.
234
235DELEGPURGE:
236  mandatory only for servers that support CLAIM_DELEGATE_PREV and/or
237  CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that
238  persist across client reboots).  Thus we need not implement this for
239  now.
240
241EXCHANGE_ID:
242  implementation ids are ignored
243
244CREATE_SESSION:
245  backchannel attributes are ignored
246
247SEQUENCE:
248  no support for dynamic slot table renegotiation (optional)
249
250Nonstandard compound limitations:
251  No support for a sessions fore channel RPC compound that requires both a
252  ca_maxrequestsize request and a ca_maxresponsesize reply, so we may
253  fail to live up to the promise we made in CREATE_SESSION fore channel
254  negotiation.
255
256See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues.
257