diff options
Diffstat (limited to 'Documentation/filesystems/nfs/nfs41-server.txt')
| -rw-r--r-- | Documentation/filesystems/nfs/nfs41-server.txt | 60 |
1 files changed, 16 insertions, 44 deletions
diff --git a/Documentation/filesystems/nfs/nfs41-server.txt b/Documentation/filesystems/nfs/nfs41-server.txt index 092fad92a3f..c49cd7e796e 100644 --- a/Documentation/filesystems/nfs/nfs41-server.txt +++ b/Documentation/filesystems/nfs/nfs41-server.txt @@ -5,11 +5,11 @@ Server support for minorversion 1 can be controlled using the by reading this file will contain either "+4.1" or "-4.1" correspondingly. -Currently, server support for minorversion 1 is disabled by default. -It can be enabled at run time by writing the string "+4.1" to +Currently, server support for minorversion 1 is enabled by default. +It can be disabled at run time by writing the string "-4.1" to the /proc/fs/nfsd/versions control file. Note that to write this -control file, the nfsd service must be taken down. Use your user-mode -nfs-utils to set this up; see rpc.nfsd(8) +control file, the nfsd service must be taken down. You can use rpc.nfsd +for this; see rpc.nfsd(8). (Warning: older servers will interpret "+4.1" and "-4.1" as "+4" and "-4", respectively. Therefore, code meant to work on both new and old @@ -29,40 +29,6 @@ are still under development out of tree. See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design for more information. -The current implementation is intended for developers only: while it -does support ordinary file operations on clients we have tested against -(including the linux client), it is incomplete in ways which may limit -features unexpectedly, cause known bugs in rare cases, or cause -interoperability problems with future clients. Known issues: - - - gss support is questionable: currently mounts with kerberos - from a linux client are possible, but we aren't really - conformant with the spec (for example, we don't use kerberos - on the backchannel correctly). - - Incomplete backchannel support: incomplete backchannel gss - support and no support for BACKCHANNEL_CTL mean that - callbacks (hence delegations and layouts) may not be - available and clients confused by the incomplete - implementation may fail. - - We do not support SSV, which provides security for shared - client-server state (thus preventing unauthorized tampering - with locks and opens, for example). It is mandatory for - servers to support this, though no clients use it yet. - - Mandatory operations which we do not support, such as - DESTROY_CLIENTID, are not currently used by clients, but will be - (and the spec recommends their uses in common cases), and - clients should not be expected to know how to recover from the - case where they are not supported. This will eventually cause - interoperability failures. - -In addition, some limitations are inherited from the current NFSv4 -implementation: - - - Incomplete delegation enforcement: if a file is renamed or - unlinked by a local process, a client holding a delegation may - continue to indefinitely allow opens of the file under the old - name. - The table below, taken from the NFSv4.1 document, lists the operations that are mandatory to implement (REQ), optional (OPT), and NFSv4.0 operations that are required not to implement (MNI) @@ -89,7 +55,7 @@ Operations | | MNI | or OPT) | | +----------------------+------------+--------------+----------------+ | ACCESS | REQ | | Section 18.1 | -NS | BACKCHANNEL_CTL | REQ | | Section 18.33 | +I | BACKCHANNEL_CTL | REQ | | Section 18.33 | I | BIND_CONN_TO_SESSION | REQ | | Section 18.34 | | CLOSE | REQ | | Section 18.2 | | COMMIT | REQ | | Section 18.3 | @@ -99,7 +65,7 @@ NS*| DELEGPURGE | OPT | FDELG (REQ) | Section 18.5 | | DELEGRETURN | OPT | FDELG, | Section 18.6 | | | | DDELG, pNFS | | | | | (REQ) | | -NS | DESTROY_CLIENTID | REQ | | Section 18.50 | +I | DESTROY_CLIENTID | REQ | | Section 18.50 | I | DESTROY_SESSION | REQ | | Section 18.37 | I | EXCHANGE_ID | REQ | | Section 18.35 | I | FREE_STATEID | REQ | | Section 18.38 | @@ -180,6 +146,16 @@ NS*| CB_WANTS_CANCELLED | OPT | FDELG, | Section 20.10 | Implementation notes: +SSV: +* The spec claims this is mandatory, but we don't actually know of any + implementations, so we're ignoring it for now. The server returns + NFS4ERR_ENCR_ALG_UNSUPP on EXCHANGE_ID, which should be future-proof. + +GSS on the backchannel: +* Again, theoretically required but not widely implemented (in + particular, the current Linux client doesn't request it). We return + NFS4ERR_ENCR_ALG_UNSUPP on CREATE_SESSION. + DELEGPURGE: * mandatory only for servers that support CLAIM_DELEGATE_PREV and/or CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that @@ -187,12 +163,10 @@ DELEGPURGE: now. EXCHANGE_ID: -* only SP4_NONE state protection supported * implementation ids are ignored CREATE_SESSION: * backchannel attributes are ignored -* backchannel security parameters are ignored SEQUENCE: * no support for dynamic slot table renegotiation (optional) @@ -202,7 +176,5 @@ Nonstandard compound limitations: ca_maxrequestsize request and a ca_maxresponsesize reply, so we may fail to live up to the promise we made in CREATE_SESSION fore channel negotiation. -* No more than one IO operation (read, write, readdir) allowed per - compound. See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues. |