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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 disabled by default. | |
9 | It can be enabled 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. Use your user-mode | |
12 | nfs-utils to set this up; see rpc.nfsd(8) | |
13 | ||
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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 | ||
3ef17288 | 19 | The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based |
73834d6f | 20 | on RFC 5661. |
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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 | ||
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32 | The current implementation is intended for developers only: while it |
33 | does support ordinary file operations on clients we have tested against | |
34 | (including the linux client), it is incomplete in ways which may limit | |
35 | features unexpectedly, cause known bugs in rare cases, or cause | |
36 | interoperability problems with future clients. Known issues: | |
37 | ||
38 | - gss support is questionable: currently mounts with kerberos | |
39 | from a linux client are possible, but we aren't really | |
40 | conformant with the spec (for example, we don't use kerberos | |
41 | on the backchannel correctly). | |
42 | - no trunking support: no clients currently take advantage of | |
03d6a74b | 43 | trunking, but this is a mandatory feature, and its use is |
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44 | recommended to clients in a number of places. (E.g. to ensure |
45 | timely renewal in case an existing connection's retry timeouts | |
73834d6f | 46 | have gotten too long; see section 8.3 of the RFC.) |
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47 | Therefore, lack of this feature may cause future clients to |
48 | fail. | |
49 | - Incomplete backchannel support: incomplete backchannel gss | |
50 | support and no support for BACKCHANNEL_CTL mean that | |
51 | callbacks (hence delegations and layouts) may not be | |
52 | available and clients confused by the incomplete | |
53 | implementation may fail. | |
54 | - Server reboot recovery is unsupported; if the server reboots, | |
55 | clients may fail. | |
56 | - We do not support SSV, which provides security for shared | |
57 | client-server state (thus preventing unauthorized tampering | |
58 | with locks and opens, for example). It is mandatory for | |
59 | servers to support this, though no clients use it yet. | |
60 | - Mandatory operations which we do not support, such as | |
61 | DESTROY_CLIENTID, FREE_STATEID, SECINFO_NO_NAME, and | |
62 | TEST_STATEID, are not currently used by clients, but will be | |
63 | (and the spec recommends their uses in common cases), and | |
64 | clients should not be expected to know how to recover from the | |
65 | case where they are not supported. This will eventually cause | |
66 | interoperability failures. | |
67 | ||
68 | In addition, some limitations are inherited from the current NFSv4 | |
69 | implementation: | |
70 | ||
71 | - Incomplete delegation enforcement: if a file is renamed or | |
72 | unlinked, a client holding a delegation may continue to | |
73 | indefinitely allow opens of the file under the old name. | |
74 | ||
3ef17288 BH |
75 | The table below, taken from the NFSv4.1 document, lists |
76 | the operations that are mandatory to implement (REQ), optional | |
77 | (OPT), and NFSv4.0 operations that are required not to implement (MNI) | |
78 | in minor version 1. The first column indicates the operations that | |
79 | are not supported yet by the linux server implementation. | |
80 | ||
81 | The OPTIONAL features identified and their abbreviations are as follows: | |
82 | pNFS Parallel NFS | |
83 | FDELG File Delegations | |
84 | DDELG Directory Delegations | |
85 | ||
86 | The following abbreviations indicate the linux server implementation status. | |
87 | I Implemented NFSv4.1 operations. | |
88 | NS Not Supported. | |
89 | NS* unimplemented optional feature. | |
90 | P pNFS features implemented out of tree. | |
91 | PNS pNFS features that are not supported yet (out of tree). | |
92 | ||
93 | Operations | |
94 | ||
95 | +----------------------+------------+--------------+----------------+ | |
96 | | Operation | REQ, REC, | Feature | Definition | | |
97 | | | OPT, or | (REQ, REC, | | | |
98 | | | MNI | or OPT) | | | |
99 | +----------------------+------------+--------------+----------------+ | |
100 | | ACCESS | REQ | | Section 18.1 | | |
101 | NS | BACKCHANNEL_CTL | REQ | | Section 18.33 | | |
102 | NS | BIND_CONN_TO_SESSION | REQ | | Section 18.34 | | |
103 | | CLOSE | REQ | | Section 18.2 | | |
104 | | COMMIT | REQ | | Section 18.3 | | |
105 | | CREATE | REQ | | Section 18.4 | | |
106 | I | CREATE_SESSION | REQ | | Section 18.36 | | |
107 | NS*| DELEGPURGE | OPT | FDELG (REQ) | Section 18.5 | | |
108 | | DELEGRETURN | OPT | FDELG, | Section 18.6 | | |
109 | | | | DDELG, pNFS | | | |
110 | | | | (REQ) | | | |
111 | NS | DESTROY_CLIENTID | REQ | | Section 18.50 | | |
112 | I | DESTROY_SESSION | REQ | | Section 18.37 | | |
113 | I | EXCHANGE_ID | REQ | | Section 18.35 | | |
114 | NS | FREE_STATEID | REQ | | Section 18.38 | | |
115 | | GETATTR | REQ | | Section 18.7 | | |
116 | P | GETDEVICEINFO | OPT | pNFS (REQ) | Section 18.40 | | |
117 | P | GETDEVICELIST | OPT | pNFS (OPT) | Section 18.41 | | |
118 | | GETFH | REQ | | Section 18.8 | | |
119 | NS*| GET_DIR_DELEGATION | OPT | DDELG (REQ) | Section 18.39 | | |
120 | P | LAYOUTCOMMIT | OPT | pNFS (REQ) | Section 18.42 | | |
121 | P | LAYOUTGET | OPT | pNFS (REQ) | Section 18.43 | | |
122 | P | LAYOUTRETURN | OPT | pNFS (REQ) | Section 18.44 | | |
123 | | LINK | OPT | | Section 18.9 | | |
124 | | LOCK | REQ | | Section 18.10 | | |
125 | | LOCKT | REQ | | Section 18.11 | | |
126 | | LOCKU | REQ | | Section 18.12 | | |
127 | | LOOKUP | REQ | | Section 18.13 | | |
128 | | LOOKUPP | REQ | | Section 18.14 | | |
129 | | NVERIFY | REQ | | Section 18.15 | | |
130 | | OPEN | REQ | | Section 18.16 | | |
131 | NS*| OPENATTR | OPT | | Section 18.17 | | |
132 | | OPEN_CONFIRM | MNI | | N/A | | |
133 | | OPEN_DOWNGRADE | REQ | | Section 18.18 | | |
134 | | PUTFH | REQ | | Section 18.19 | | |
135 | | PUTPUBFH | REQ | | Section 18.20 | | |
136 | | PUTROOTFH | REQ | | Section 18.21 | | |
137 | | READ | REQ | | Section 18.22 | | |
138 | | READDIR | REQ | | Section 18.23 | | |
139 | | READLINK | OPT | | Section 18.24 | | |
4dc6ec00 | 140 | | RECLAIM_COMPLETE | REQ | | Section 18.51 | |
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141 | | RELEASE_LOCKOWNER | MNI | | N/A | |
142 | | REMOVE | REQ | | Section 18.25 | | |
143 | | RENAME | REQ | | Section 18.26 | | |
144 | | RENEW | MNI | | N/A | | |
145 | | RESTOREFH | REQ | | Section 18.27 | | |
146 | | SAVEFH | REQ | | Section 18.28 | | |
147 | | SECINFO | REQ | | Section 18.29 | | |
148 | NS | SECINFO_NO_NAME | REC | pNFS files | Section 18.45, | | |
149 | | | | layout (REQ) | Section 13.12 | | |
150 | I | SEQUENCE | REQ | | Section 18.46 | | |
151 | | SETATTR | REQ | | Section 18.30 | | |
152 | | SETCLIENTID | MNI | | N/A | | |
153 | | SETCLIENTID_CONFIRM | MNI | | N/A | | |
154 | NS | SET_SSV | REQ | | Section 18.47 | | |
155 | NS | TEST_STATEID | REQ | | Section 18.48 | | |
156 | | VERIFY | REQ | | Section 18.31 | | |
157 | NS*| WANT_DELEGATION | OPT | FDELG (OPT) | Section 18.49 | | |
158 | | WRITE | REQ | | Section 18.32 | | |
159 | ||
160 | Callback Operations | |
161 | ||
162 | +-------------------------+-----------+-------------+---------------+ | |
163 | | Operation | REQ, REC, | Feature | Definition | | |
164 | | | OPT, or | (REQ, REC, | | | |
165 | | | MNI | or OPT) | | | |
166 | +-------------------------+-----------+-------------+---------------+ | |
167 | | CB_GETATTR | OPT | FDELG (REQ) | Section 20.1 | | |
168 | P | CB_LAYOUTRECALL | OPT | pNFS (REQ) | Section 20.3 | | |
169 | NS*| CB_NOTIFY | OPT | DDELG (REQ) | Section 20.4 | | |
170 | P | CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | Section 20.12 | | |
171 | NS*| CB_NOTIFY_LOCK | OPT | | Section 20.11 | | |
172 | NS*| CB_PUSH_DELEG | OPT | FDELG (OPT) | Section 20.5 | | |
173 | | CB_RECALL | OPT | FDELG, | Section 20.2 | | |
174 | | | | DDELG, pNFS | | | |
175 | | | | (REQ) | | | |
176 | NS*| CB_RECALL_ANY | OPT | FDELG, | Section 20.6 | | |
177 | | | | DDELG, pNFS | | | |
178 | | | | (REQ) | | | |
179 | NS | CB_RECALL_SLOT | REQ | | Section 20.8 | | |
180 | NS*| CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS | Section 20.7 | | |
181 | | | | (REQ) | | | |
182 | I | CB_SEQUENCE | OPT | FDELG, | Section 20.9 | | |
183 | | | | DDELG, pNFS | | | |
184 | | | | (REQ) | | | |
185 | NS*| CB_WANTS_CANCELLED | OPT | FDELG, | Section 20.10 | | |
186 | | | | DDELG, pNFS | | | |
187 | | | | (REQ) | | | |
188 | +-------------------------+-----------+-------------+---------------+ | |
189 | ||
190 | Implementation notes: | |
191 | ||
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192 | DELEGPURGE: |
193 | * mandatory only for servers that support CLAIM_DELEGATE_PREV and/or | |
194 | CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that | |
195 | persist across client reboots). Thus we need not implement this for | |
196 | now. | |
197 | ||
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198 | EXCHANGE_ID: |
199 | * only SP4_NONE state protection supported | |
200 | * implementation ids are ignored | |
201 | ||
202 | CREATE_SESSION: | |
203 | * backchannel attributes are ignored | |
204 | * backchannel security parameters are ignored | |
205 | ||
206 | SEQUENCE: | |
207 | * no support for dynamic slot table renegotiation (optional) | |
208 | ||
209 | nfsv4.1 COMPOUND rules: | |
210 | The following cases aren't supported yet: | |
211 | * Enforcing of NFS4ERR_NOT_ONLY_OP for: BIND_CONN_TO_SESSION, CREATE_SESSION, | |
212 | DESTROY_CLIENTID, DESTROY_SESSION, EXCHANGE_ID. | |
213 | * DESTROY_SESSION MUST be the final operation in the COMPOUND request. | |
214 | ||
ddc04fd4 AA |
215 | Nonstandard compound limitations: |
216 | * No support for a sessions fore channel RPC compound that requires both a | |
217 | ca_maxrequestsize request and a ca_maxresponsesize reply, so we may | |
218 | fail to live up to the promise we made in CREATE_SESSION fore channel | |
219 | negotiation. | |
220 | * No more than one IO operation (read, write, readdir) allowed per | |
221 | compound. |