Documentation/filesystems/nfs/nfs41-server.rst

   1 =============================
   2 NFSv4.1 Server Implementation
   3 =============================
   4
   5 Server support for minorversion 1 can be controlled using the
   6 /proc/fs/nfsd/versions control file.  The string output returned
   7 by reading this file will contain either "+4.1" or "-4.1"
   8 correspondingly.
   9
  10 Currently, server support for minorversion 1 is enabled by default.
  11 It can be disabled at run time by writing the string "-4.1" to
  12 the /proc/fs/nfsd/versions control file.  Note that to write this
  13 control file, the nfsd service must be taken down.  You can use rpc.nfsd
  14 for 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
  18 kernels must turn 4.1 on or off *before* turning support for version 4
  19 on or off; rpc.nfsd does this correctly.)
  20
  21 The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
  22 on RFC 5661.
  23
  24 From the many new features in NFSv4.1 the current implementation
  25 focuses on the mandatory-to-implement NFSv4.1 Sessions, providing
  26 "exactly once" semantics and better control and throttling of the
  27 resources allocated for each client.
  28
  29 The table below, taken from the NFSv4.1 document, lists
  30 the operations that are mandatory to implement (REQ), optional
  31 (OPT), and NFSv4.0 operations that are required not to implement (MNI)
  32 in minor version 1.  The first column indicates the operations that
  33 are not supported yet by the linux server implementation.
  34
  35 The OPTIONAL features identified and their abbreviations are as follows:
  36
  37 - **pNFS**      Parallel NFS
  38 - **FDELG**     File Delegations
  39 - **DDELG**     Directory Delegations
  40
  41 The 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
  47 Operations
  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
 173 Callback 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
 222 Implementation notes:
 223 =====================
 224
 225 SSV:
 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
 230 GSS 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
 235 DELEGPURGE:
 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
 241 EXCHANGE_ID:
 242   implementation ids are ignored
 243
 244 CREATE_SESSION:
 245   backchannel attributes are ignored
 246
 247 SEQUENCE:
 248   no support for dynamic slot table renegotiation (optional)
 249
 250 Nonstandard 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
 256 See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues.