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1 NFSv4.1 Server Implementation
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.
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).
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.)
19 The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
20 on RFC 5661.
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.
27 The table below, taken from the NFSv4.1 document, lists
28 the operations that are mandatory to implement (REQ), optional
29 (OPT), and NFSv4.0 operations that are required not to implement (MNI)
30 in minor version 1. The first column indicates the operations that
31 are not supported yet by the linux server implementation.
33 The OPTIONAL features identified and their abbreviations are as follows:
34 pNFS Parallel NFS
35 FDELG File Delegations
36 DDELG Directory Delegations
38 The following abbreviations indicate the linux server implementation status.
39 I Implemented NFSv4.1 operations.
40 NS Not Supported.
41 NS* Unimplemented optional feature.
43 Operations
45 +----------------------+------------+--------------+----------------+
46 | Operation | REQ, REC, | Feature | Definition |
47 | | OPT, or | (REQ, REC, | |
48 | | MNI | or OPT) | |
49 +----------------------+------------+--------------+----------------+
50 | ACCESS | REQ | | Section 18.1 |
51 I | BACKCHANNEL_CTL | REQ | | Section 18.33 |
52 I | BIND_CONN_TO_SESSION | REQ | | Section 18.34 |
53 | CLOSE | REQ | | Section 18.2 |
54 | COMMIT | REQ | | Section 18.3 |
55 | CREATE | REQ | | Section 18.4 |
56 I | CREATE_SESSION | REQ | | Section 18.36 |
57 NS*| DELEGPURGE | OPT | FDELG (REQ) | Section 18.5 |
58 | DELEGRETURN | OPT | FDELG, | Section 18.6 |
59 | | | DDELG, pNFS | |
60 | | | (REQ) | |
61 I | DESTROY_CLIENTID | REQ | | Section 18.50 |
62 I | DESTROY_SESSION | REQ | | Section 18.37 |
63 I | EXCHANGE_ID | REQ | | Section 18.35 |
64 I | FREE_STATEID | REQ | | Section 18.38 |
65 | GETATTR | REQ | | Section 18.7 |
66 I | GETDEVICEINFO | OPT | pNFS (REQ) | Section 18.40 |
67 NS*| GETDEVICELIST | OPT | pNFS (OPT) | Section 18.41 |
68 | GETFH | REQ | | Section 18.8 |
69 NS*| GET_DIR_DELEGATION | OPT | DDELG (REQ) | Section 18.39 |
70 I | LAYOUTCOMMIT | OPT | pNFS (REQ) | Section 18.42 |
71 I | LAYOUTGET | OPT | pNFS (REQ) | Section 18.43 |
72 I | LAYOUTRETURN | OPT | pNFS (REQ) | Section 18.44 |
73 | LINK | OPT | | Section 18.9 |
74 | LOCK | REQ | | Section 18.10 |
75 | LOCKT | REQ | | Section 18.11 |
76 | LOCKU | REQ | | Section 18.12 |
77 | LOOKUP | REQ | | Section 18.13 |
78 | LOOKUPP | REQ | | Section 18.14 |
79 | NVERIFY | REQ | | Section 18.15 |
80 | OPEN | REQ | | Section 18.16 |
81 NS*| OPENATTR | OPT | | Section 18.17 |
82 | OPEN_CONFIRM | MNI | | N/A |
83 | OPEN_DOWNGRADE | REQ | | Section 18.18 |
84 | PUTFH | REQ | | Section 18.19 |
85 | PUTPUBFH | REQ | | Section 18.20 |
86 | PUTROOTFH | REQ | | Section 18.21 |
87 | READ | REQ | | Section 18.22 |
88 | READDIR | REQ | | Section 18.23 |
89 | READLINK | OPT | | Section 18.24 |
90 | RECLAIM_COMPLETE | REQ | | Section 18.51 |
91 | RELEASE_LOCKOWNER | MNI | | N/A |
92 | REMOVE | REQ | | Section 18.25 |
93 | RENAME | REQ | | Section 18.26 |
94 | RENEW | MNI | | N/A |
95 | RESTOREFH | REQ | | Section 18.27 |
96 | SAVEFH | REQ | | Section 18.28 |
97 | SECINFO | REQ | | Section 18.29 |
98 I | SECINFO_NO_NAME | REC | pNFS files | Section 18.45, |
99 | | | layout (REQ) | Section 13.12 |
100 I | SEQUENCE | REQ | | Section 18.46 |
101 | SETATTR | REQ | | Section 18.30 |
102 | SETCLIENTID | MNI | | N/A |
103 | SETCLIENTID_CONFIRM | MNI | | N/A |
104 NS | SET_SSV | REQ | | Section 18.47 |
105 I | TEST_STATEID | REQ | | Section 18.48 |
106 | VERIFY | REQ | | Section 18.31 |
107 NS*| WANT_DELEGATION | OPT | FDELG (OPT) | Section 18.49 |
108 | WRITE | REQ | | Section 18.32 |
110 Callback Operations
112 +-------------------------+-----------+-------------+---------------+
113 | Operation | REQ, REC, | Feature | Definition |
114 | | OPT, or | (REQ, REC, | |
115 | | MNI | or OPT) | |
116 +-------------------------+-----------+-------------+---------------+
117 | CB_GETATTR | OPT | FDELG (REQ) | Section 20.1 |
118 I | CB_LAYOUTRECALL | OPT | pNFS (REQ) | Section 20.3 |
119 NS*| CB_NOTIFY | OPT | DDELG (REQ) | Section 20.4 |
120 NS*| CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | Section 20.12 |
121 NS*| CB_NOTIFY_LOCK | OPT | | Section 20.11 |
122 NS*| CB_PUSH_DELEG | OPT | FDELG (OPT) | Section 20.5 |
123 | CB_RECALL | OPT | FDELG, | Section 20.2 |
124 | | | DDELG, pNFS | |
125 | | | (REQ) | |
126 NS*| CB_RECALL_ANY | OPT | FDELG, | Section 20.6 |
127 | | | DDELG, pNFS | |
128 | | | (REQ) | |
129 NS | CB_RECALL_SLOT | REQ | | Section 20.8 |
130 NS*| CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS | Section 20.7 |
131 | | | (REQ) | |
132 I | CB_SEQUENCE | OPT | FDELG, | Section 20.9 |
133 | | | DDELG, pNFS | |
134 | | | (REQ) | |
135 NS*| CB_WANTS_CANCELLED | OPT | FDELG, | Section 20.10 |
136 | | | DDELG, pNFS | |
137 | | | (REQ) | |
138 +-------------------------+-----------+-------------+---------------+
140 Implementation notes:
142 SSV:
143 * The spec claims this is mandatory, but we don't actually know of any
144 implementations, so we're ignoring it for now. The server returns
145 NFS4ERR_ENCR_ALG_UNSUPP on EXCHANGE_ID, which should be future-proof.
147 GSS on the backchannel:
148 * Again, theoretically required but not widely implemented (in
149 particular, the current Linux client doesn't request it). We return
150 NFS4ERR_ENCR_ALG_UNSUPP on CREATE_SESSION.
152 DELEGPURGE:
153 * mandatory only for servers that support CLAIM_DELEGATE_PREV and/or
154 CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that
155 persist across client reboots). Thus we need not implement this for
156 now.
158 EXCHANGE_ID:
159 * implementation ids are ignored
161 CREATE_SESSION:
162 * backchannel attributes are ignored
164 SEQUENCE:
165 * no support for dynamic slot table renegotiation (optional)
167 Nonstandard compound limitations:
168 * No support for a sessions fore channel RPC compound that requires both a
169 ca_maxrequestsize request and a ca_maxresponsesize reply, so we may
170 fail to live up to the promise we made in CREATE_SESSION fore channel
171 negotiation.
173 See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues.