1NFSv4.1 Server Implementation 2 3Server support for minorversion 1 can be controlled using the 4/proc/fs/nfsd/versions control file. The string output returned 5by reading this file will contain either "+4.1" or "-4.1" 6correspondingly. 7 8Currently, server support for minorversion 1 is enabled by default. 9It can be disabled at run time by writing the string "-4.1" to 10the /proc/fs/nfsd/versions control file. Note that to write this 11control file, the nfsd service must be taken down. You can use rpc.nfsd 12for 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 16kernels must turn 4.1 on or off *before* turning support for version 4 17on or off; rpc.nfsd does this correctly.) 18 19The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based 20on RFC 5661. 21 22From the many new features in NFSv4.1 the current implementation 23focuses on the mandatory-to-implement NFSv4.1 Sessions, providing 24"exactly once" semantics and better control and throttling of the 25resources allocated for each client. 26 27Other NFSv4.1 features, Parallel NFS operations in particular, 28are still under development out of tree. 29See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design 30for more information. 31 32The table below, taken from the NFSv4.1 document, lists 33the operations that are mandatory to implement (REQ), optional 34(OPT), and NFSv4.0 operations that are required not to implement (MNI) 35in minor version 1. The first column indicates the operations that 36are not supported yet by the linux server implementation. 37 38The OPTIONAL features identified and their abbreviations are as follows: 39 pNFS Parallel NFS 40 FDELG File Delegations 41 DDELG Directory Delegations 42 43The 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 50Operations 51 52 +----------------------+------------+--------------+----------------+ 53 | Operation | REQ, REC, | Feature | Definition | 54 | | OPT, or | (REQ, REC, | | 55 | | MNI | or OPT) | | 56 +----------------------+------------+--------------+----------------+ 57 | ACCESS | REQ | | Section 18.1 | 58I | BACKCHANNEL_CTL | REQ | | Section 18.33 | 59I | 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 | 63I | CREATE_SESSION | REQ | | Section 18.36 | 64NS*| DELEGPURGE | OPT | FDELG (REQ) | Section 18.5 | 65 | DELEGRETURN | OPT | FDELG, | Section 18.6 | 66 | | | DDELG, pNFS | | 67 | | | (REQ) | | 68I | DESTROY_CLIENTID | REQ | | Section 18.50 | 69I | DESTROY_SESSION | REQ | | Section 18.37 | 70I | EXCHANGE_ID | REQ | | Section 18.35 | 71I | FREE_STATEID | REQ | | Section 18.38 | 72 | GETATTR | REQ | | Section 18.7 | 73P | GETDEVICEINFO | OPT | pNFS (REQ) | Section 18.40 | 74P | GETDEVICELIST | OPT | pNFS (OPT) | Section 18.41 | 75 | GETFH | REQ | | Section 18.8 | 76NS*| GET_DIR_DELEGATION | OPT | DDELG (REQ) | Section 18.39 | 77P | LAYOUTCOMMIT | OPT | pNFS (REQ) | Section 18.42 | 78P | LAYOUTGET | OPT | pNFS (REQ) | Section 18.43 | 79P | 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 | 88NS*| 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 | 105I | SECINFO_NO_NAME | REC | pNFS files | Section 18.45, | 106 | | | layout (REQ) | Section 13.12 | 107I | SEQUENCE | REQ | | Section 18.46 | 108 | SETATTR | REQ | | Section 18.30 | 109 | SETCLIENTID | MNI | | N/A | 110 | SETCLIENTID_CONFIRM | MNI | | N/A | 111NS | SET_SSV | REQ | | Section 18.47 | 112I | TEST_STATEID | REQ | | Section 18.48 | 113 | VERIFY | REQ | | Section 18.31 | 114NS*| WANT_DELEGATION | OPT | FDELG (OPT) | Section 18.49 | 115 | WRITE | REQ | | Section 18.32 | 116 117Callback 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 | 125P | CB_LAYOUTRECALL | OPT | pNFS (REQ) | Section 20.3 | 126NS*| CB_NOTIFY | OPT | DDELG (REQ) | Section 20.4 | 127P | CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | Section 20.12 | 128NS*| CB_NOTIFY_LOCK | OPT | | Section 20.11 | 129NS*| CB_PUSH_DELEG | OPT | FDELG (OPT) | Section 20.5 | 130 | CB_RECALL | OPT | FDELG, | Section 20.2 | 131 | | | DDELG, pNFS | | 132 | | | (REQ) | | 133NS*| CB_RECALL_ANY | OPT | FDELG, | Section 20.6 | 134 | | | DDELG, pNFS | | 135 | | | (REQ) | | 136NS | CB_RECALL_SLOT | REQ | | Section 20.8 | 137NS*| CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS | Section 20.7 | 138 | | | (REQ) | | 139I | CB_SEQUENCE | OPT | FDELG, | Section 20.9 | 140 | | | DDELG, pNFS | | 141 | | | (REQ) | | 142NS*| CB_WANTS_CANCELLED | OPT | FDELG, | Section 20.10 | 143 | | | DDELG, pNFS | | 144 | | | (REQ) | | 145 +-------------------------+-----------+-------------+---------------+ 146 147Implementation notes: 148 149SSV: 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 154GSS 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 159DELEGPURGE: 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 165EXCHANGE_ID: 166* implementation ids are ignored 167 168CREATE_SESSION: 169* backchannel attributes are ignored 170 171SEQUENCE: 172* no support for dynamic slot table renegotiation (optional) 173 174Nonstandard 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 180See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues. 181