Documentation / filesystems / nfs / nfs41-server.txt
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Based on kernel version 3.9. Page generated on 2013-05-02 23:06 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 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 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 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 - We do not support SSV, which provides security for shared 43 client-server state (thus preventing unauthorized tampering 44 with locks and opens, for example). It is mandatory for 45 servers to support this, though no clients use it yet. 46 47 In addition, some limitations are inherited from the current NFSv4 48 implementation: 49 50 - Incomplete delegation enforcement: if a file is renamed or 51 unlinked by a local process, a client holding a delegation may 52 continue to indefinitely allow opens of the file under the old 53 name. 54 55 The table below, taken from the NFSv4.1 document, lists 56 the operations that are mandatory to implement (REQ), optional 57 (OPT), and NFSv4.0 operations that are required not to implement (MNI) 58 in minor version 1. The first column indicates the operations that 59 are not supported yet by the linux server implementation. 60 61 The OPTIONAL features identified and their abbreviations are as follows: 62 pNFS Parallel NFS 63 FDELG File Delegations 64 DDELG Directory Delegations 65 66 The following abbreviations indicate the linux server implementation status. 67 I Implemented NFSv4.1 operations. 68 NS Not Supported. 69 NS* unimplemented optional feature. 70 P pNFS features implemented out of tree. 71 PNS pNFS features that are not supported yet (out of tree). 72 73 Operations 74 75 +----------------------+------------+--------------+----------------+ 76 | Operation | REQ, REC, | Feature | Definition | 77 | | OPT, or | (REQ, REC, | | 78 | | MNI | or OPT) | | 79 +----------------------+------------+--------------+----------------+ 80 | ACCESS | REQ | | Section 18.1 | 81 I | BACKCHANNEL_CTL | REQ | | Section 18.33 | 82 I | BIND_CONN_TO_SESSION | REQ | | Section 18.34 | 83 | CLOSE | REQ | | Section 18.2 | 84 | COMMIT | REQ | | Section 18.3 | 85 | CREATE | REQ | | Section 18.4 | 86 I | CREATE_SESSION | REQ | | Section 18.36 | 87 NS*| DELEGPURGE | OPT | FDELG (REQ) | Section 18.5 | 88 | DELEGRETURN | OPT | FDELG, | Section 18.6 | 89 | | | DDELG, pNFS | | 90 | | | (REQ) | | 91 I | DESTROY_CLIENTID | REQ | | Section 18.50 | 92 I | DESTROY_SESSION | REQ | | Section 18.37 | 93 I | EXCHANGE_ID | REQ | | Section 18.35 | 94 I | FREE_STATEID | REQ | | Section 18.38 | 95 | GETATTR | REQ | | Section 18.7 | 96 P | GETDEVICEINFO | OPT | pNFS (REQ) | Section 18.40 | 97 P | GETDEVICELIST | OPT | pNFS (OPT) | Section 18.41 | 98 | GETFH | REQ | | Section 18.8 | 99 NS*| GET_DIR_DELEGATION | OPT | DDELG (REQ) | Section 18.39 | 100 P | LAYOUTCOMMIT | OPT | pNFS (REQ) | Section 18.42 | 101 P | LAYOUTGET | OPT | pNFS (REQ) | Section 18.43 | 102 P | LAYOUTRETURN | OPT | pNFS (REQ) | Section 18.44 | 103 | LINK | OPT | | Section 18.9 | 104 | LOCK | REQ | | Section 18.10 | 105 | LOCKT | REQ | | Section 18.11 | 106 | LOCKU | REQ | | Section 18.12 | 107 | LOOKUP | REQ | | Section 18.13 | 108 | LOOKUPP | REQ | | Section 18.14 | 109 | NVERIFY | REQ | | Section 18.15 | 110 | OPEN | REQ | | Section 18.16 | 111 NS*| OPENATTR | OPT | | Section 18.17 | 112 | OPEN_CONFIRM | MNI | | N/A | 113 | OPEN_DOWNGRADE | REQ | | Section 18.18 | 114 | PUTFH | REQ | | Section 18.19 | 115 | PUTPUBFH | REQ | | Section 18.20 | 116 | PUTROOTFH | REQ | | Section 18.21 | 117 | READ | REQ | | Section 18.22 | 118 | READDIR | REQ | | Section 18.23 | 119 | READLINK | OPT | | Section 18.24 | 120 | RECLAIM_COMPLETE | REQ | | Section 18.51 | 121 | RELEASE_LOCKOWNER | MNI | | N/A | 122 | REMOVE | REQ | | Section 18.25 | 123 | RENAME | REQ | | Section 18.26 | 124 | RENEW | MNI | | N/A | 125 | RESTOREFH | REQ | | Section 18.27 | 126 | SAVEFH | REQ | | Section 18.28 | 127 | SECINFO | REQ | | Section 18.29 | 128 I | SECINFO_NO_NAME | REC | pNFS files | Section 18.45, | 129 | | | layout (REQ) | Section 13.12 | 130 I | SEQUENCE | REQ | | Section 18.46 | 131 | SETATTR | REQ | | Section 18.30 | 132 | SETCLIENTID | MNI | | N/A | 133 | SETCLIENTID_CONFIRM | MNI | | N/A | 134 NS | SET_SSV | REQ | | Section 18.47 | 135 I | TEST_STATEID | REQ | | Section 18.48 | 136 | VERIFY | REQ | | Section 18.31 | 137 NS*| WANT_DELEGATION | OPT | FDELG (OPT) | Section 18.49 | 138 | WRITE | REQ | | Section 18.32 | 139 140 Callback Operations 141 142 +-------------------------+-----------+-------------+---------------+ 143 | Operation | REQ, REC, | Feature | Definition | 144 | | OPT, or | (REQ, REC, | | 145 | | MNI | or OPT) | | 146 +-------------------------+-----------+-------------+---------------+ 147 | CB_GETATTR | OPT | FDELG (REQ) | Section 20.1 | 148 P | CB_LAYOUTRECALL | OPT | pNFS (REQ) | Section 20.3 | 149 NS*| CB_NOTIFY | OPT | DDELG (REQ) | Section 20.4 | 150 P | CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | Section 20.12 | 151 NS*| CB_NOTIFY_LOCK | OPT | | Section 20.11 | 152 NS*| CB_PUSH_DELEG | OPT | FDELG (OPT) | Section 20.5 | 153 | CB_RECALL | OPT | FDELG, | Section 20.2 | 154 | | | DDELG, pNFS | | 155 | | | (REQ) | | 156 NS*| CB_RECALL_ANY | OPT | FDELG, | Section 20.6 | 157 | | | DDELG, pNFS | | 158 | | | (REQ) | | 159 NS | CB_RECALL_SLOT | REQ | | Section 20.8 | 160 NS*| CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS | Section 20.7 | 161 | | | (REQ) | | 162 I | CB_SEQUENCE | OPT | FDELG, | Section 20.9 | 163 | | | DDELG, pNFS | | 164 | | | (REQ) | | 165 NS*| CB_WANTS_CANCELLED | OPT | FDELG, | Section 20.10 | 166 | | | DDELG, pNFS | | 167 | | | (REQ) | | 168 +-------------------------+-----------+-------------+---------------+ 169 170 Implementation notes: 171 172 DELEGPURGE: 173 * mandatory only for servers that support CLAIM_DELEGATE_PREV and/or 174 CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that 175 persist across client reboots). Thus we need not implement this for 176 now. 177 178 EXCHANGE_ID: 179 * only SP4_NONE state protection supported 180 * implementation ids are ignored 181 182 CREATE_SESSION: 183 * backchannel attributes are ignored 184 185 SEQUENCE: 186 * no support for dynamic slot table renegotiation (optional) 187 188 Nonstandard compound limitations: 189 * No support for a sessions fore channel RPC compound that requires both a 190 ca_maxrequestsize request and a ca_maxresponsesize reply, so we may 191 fail to live up to the promise we made in CREATE_SESSION fore channel 192 negotiation. 193 * No more than one read-like operation allowed per compound; encoding 194 replies that cross page boundaries (except for read data) not handled. 195 196 See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues.
- [ nfs ]
- 00-INDEX
- Exporting
- fault_injection.txt
- idmapper.txt
- knfsd-stats.txt
- nfs-rdma.txt
- nfs.txt
- nfs41-server.txt
- nfsd-admin-interfaces.txt
- nfsroot.txt
- pnfs.txt
- rpc-cache.txt
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