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authorLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:54:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:54:33 -0700
commita87e84b5cdfacf11af4e8a85c4bca9793658536f (patch)
treef8e3cb2d339d8ed0e987d55f725e501730cdc81d /Documentation
parent342ff1a1b558ebbdb8cbd55ab6a63eca8b2473ca (diff)
parent3c394ddaa7ea4205f933fd9b481166b2669368a9 (diff)
Merge branch 'for-2.6.32' of git://linux-nfs.org/~bfields/linux
* 'for-2.6.32' of git://linux-nfs.org/~bfields/linux: (68 commits) nfsd4: nfsv4 clients should cross mountpoints nfsd: revise 4.1 status documentation sunrpc/cache: avoid variable over-loading in cache_defer_req sunrpc/cache: use list_del_init for the list_head entries in cache_deferred_req nfsd: return success for non-NFS4 nfs4_state_start nfsd41: Refactor create_client() nfsd41: modify nfsd4.1 backchannel to use new xprt class nfsd41: Backchannel: Implement cb_recall over NFSv4.1 nfsd41: Backchannel: cb_sequence callback nfsd41: Backchannel: Setup sequence information nfsd41: Backchannel: Server backchannel RPC wait queue nfsd41: Backchannel: Add sequence arguments to callback RPC arguments nfsd41: Backchannel: callback infrastructure nfsd4: use common rpc_cred for all callbacks nfsd4: allow nfs4 state startup to fail SUNRPC: Defer the auth_gss upcall when the RPC call is asynchronous nfsd4: fix null dereference creating nfsv4 callback client nfsd4: fix whitespace in NFSPROC4_CLNT_CB_NULL definition nfsd41: sunrpc: add new xprt class for nfsv4.1 backchannel sunrpc/cache: simplify cache_fresh_locked and cache_fresh_unlocked. ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/nfs41-server.txt54
1 files changed, 54 insertions, 0 deletions
diff --git a/Documentation/filesystems/nfs41-server.txt b/Documentation/filesystems/nfs41-server.txt
index 05d81cbcb2e1..5920fe26e6ff 100644
--- a/Documentation/filesystems/nfs41-server.txt
+++ b/Documentation/filesystems/nfs41-server.txt
@@ -11,6 +11,11 @@ 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)
+(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
+kernels must turn 4.1 on or off *before* turning support for version 4
+on or off; rpc.nfsd does this correctly.)
+
The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
on the latest NFSv4.1 Internet Draft:
http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-29
@@ -25,6 +30,49 @@ 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).
+ - no trunking support: no clients currently take advantage of
+ trunking, but this is a mandatory failure, and its use is
+ recommended to clients in a number of places. (E.g. to ensure
+ timely renewal in case an existing connection's retry timeouts
+ have gotten too long; see section 8.3 of the draft.)
+ Therefore, lack of this feature may cause future clients to
+ fail.
+ - 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.
+ - Server reboot recovery is unsupported; if the server reboots,
+ clients 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, FREE_STATEID, SECINFO_NO_NAME, and
+ TEST_STATEID, 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, 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)
@@ -142,6 +190,12 @@ NS*| CB_WANTS_CANCELLED | OPT | FDELG, | Section 20.10 |
Implementation notes:
+DELEGPURGE:
+* mandatory only for servers that support CLAIM_DELEGATE_PREV and/or
+ CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that
+ persist across client reboots). Thus we need not implement this for
+ now.
+
EXCHANGE_ID:
* only SP4_NONE state protection supported
* implementation ids are ignored