Documentation/filesystems/nfs/nfs41-server.txt

   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 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).
  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 table below, taken from the NFSv4.1 document, lists
  33 the operations that are mandatory to implement (REQ), optional
  34 (OPT), and NFSv4.0 operations that are required not to implement (MNI)
  35 in minor version 1.  The first column indicates the operations that
  36 are not supported yet by the linux server implementation.
  37
  38 The OPTIONAL features identified and their abbreviations are as follows:
  39         pNFS    Parallel NFS
  40         FDELG   File Delegations
  41         DDELG   Directory Delegations
  42
  43 The 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
  50 Operations
  51
  52    +----------------------+------------+--------------+----------------+
  53    | Operation            | REQ, REC,  | Feature      | Definition     |
  54    |                      | OPT, or    | (REQ, REC,   |                |
  55    |                      | MNI        | or OPT)      |                |
  56    +----------------------+------------+--------------+----------------+
  57    | ACCESS               | REQ        |              | Section 18.1   |
  58 I  | BACKCHANNEL_CTL      | REQ        |              | Section 18.33  |
  59 I  | 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   |
  63 I  | CREATE_SESSION       | REQ        |              | Section 18.36  |
  64 NS*| DELEGPURGE           | OPT        | FDELG (REQ)  | Section 18.5   |
  65    | DELEGRETURN          | OPT        | FDELG,       | Section 18.6   |
  66    |                      |            | DDELG, pNFS  |                |
  67    |                      |            | (REQ)        |                |
  68 I  | DESTROY_CLIENTID     | REQ        |              | Section 18.50  |
  69 I  | DESTROY_SESSION      | REQ        |              | Section 18.37  |
  70 I  | EXCHANGE_ID          | REQ        |              | Section 18.35  |
  71 I  | FREE_STATEID         | REQ        |              | Section 18.38  |
  72    | GETATTR              | REQ        |              | Section 18.7   |
  73 P  | GETDEVICEINFO        | OPT        | pNFS (REQ)   | Section 18.40  |
  74 P  | GETDEVICELIST        | OPT        | pNFS (OPT)   | Section 18.41  |
  75    | GETFH                | REQ        |              | Section 18.8   |
  76 NS*| GET_DIR_DELEGATION   | OPT        | DDELG (REQ)  | Section 18.39  |
  77 P  | LAYOUTCOMMIT         | OPT        | pNFS (REQ)   | Section 18.42  |
  78 P  | LAYOUTGET            | OPT        | pNFS (REQ)   | Section 18.43  |
  79 P  | 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  |
  88 NS*| 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  |
 105 I  | SECINFO_NO_NAME      | REC        | pNFS files   | Section 18.45, |
 106    |                      |            | layout (REQ) | Section 13.12  |
 107 I  | SEQUENCE             | REQ        |              | Section 18.46  |
 108    | SETATTR              | REQ        |              | Section 18.30  |
 109    | SETCLIENTID          | MNI        |              | N/A            |
 110    | SETCLIENTID_CONFIRM  | MNI        |              | N/A            |
 111 NS | SET_SSV              | REQ        |              | Section 18.47  |
 112 I  | TEST_STATEID         | REQ        |              | Section 18.48  |
 113    | VERIFY               | REQ        |              | Section 18.31  |
 114 NS*| WANT_DELEGATION      | OPT        | FDELG (OPT)  | Section 18.49  |
 115    | WRITE                | REQ        |              | Section 18.32  |
 116
 117 Callback 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  |
 125 P  | CB_LAYOUTRECALL         | OPT       | pNFS (REQ)  | Section 20.3  |
 126 NS*| CB_NOTIFY               | OPT       | DDELG (REQ) | Section 20.4  |
 127 P  | CB_NOTIFY_DEVICEID      | OPT       | pNFS (OPT)  | Section 20.12 |
 128 NS*| CB_NOTIFY_LOCK          | OPT       |             | Section 20.11 |
 129 NS*| CB_PUSH_DELEG           | OPT       | FDELG (OPT) | Section 20.5  |
 130    | CB_RECALL               | OPT       | FDELG,      | Section 20.2  |
 131    |                         |           | DDELG, pNFS |               |
 132    |                         |           | (REQ)       |               |
 133 NS*| CB_RECALL_ANY           | OPT       | FDELG,      | Section 20.6  |
 134    |                         |           | DDELG, pNFS |               |
 135    |                         |           | (REQ)       |               |
 136 NS | CB_RECALL_SLOT          | REQ       |             | Section 20.8  |
 137 NS*| CB_RECALLABLE_OBJ_AVAIL | OPT       | DDELG, pNFS | Section 20.7  |
 138    |                         |           | (REQ)       |               |
 139 I  | CB_SEQUENCE             | OPT       | FDELG,      | Section 20.9  |
 140    |                         |           | DDELG, pNFS |               |
 141    |                         |           | (REQ)       |               |
 142 NS*| CB_WANTS_CANCELLED      | OPT       | FDELG,      | Section 20.10 |
 143    |                         |           | DDELG, pNFS |               |
 144    |                         |           | (REQ)       |               |
 145    +-------------------------+-----------+-------------+---------------+
 146
 147 Implementation notes:
 148
 149 SSV:
 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
 154 GSS 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
 159 DELEGPURGE:
 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
 165 EXCHANGE_ID:
 166 * implementation ids are ignored
 167
 168 CREATE_SESSION:
 169 * backchannel attributes are ignored
 170
 171 SEQUENCE:
 172 * no support for dynamic slot table renegotiation (optional)
 173
 174 Nonstandard 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 * No more than one read-like operation allowed per compound; encoding
 180   replies that cross page boundaries (except for read data) not handled.
 181
 182 See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues.