aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation
diff options
context:
space:
mode:
authorJ. Bruce Fields <bfields@citi.umich.edu>2009-09-20 17:01:33 -0400
committerJ. Bruce Fields <bfields@citi.umich.edu>2009-09-21 11:13:45 -0400
commit285a0f00c27a02f1223a198c88de2130e9bab059 (patch)
tree32b3e2a5048fd1390cd82cd17852be78bd986cd4 /Documentation
parentcd68c374ea9ce202ae7c6346777d10078e243d49 (diff)
nfsd: revise 4.1 status documentation
Some small updates, a caveat about the minorversion control interface, and an attempt to put missing features in context. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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
11control file, the nfsd service must be taken down. Use your user-mode 11control file, the nfsd service must be taken down. Use your user-mode
12nfs-utils to set this up; see rpc.nfsd(8) 12nfs-utils to set this up; see rpc.nfsd(8)
13 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
14The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based 19The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
15on the latest NFSv4.1 Internet Draft: 20on the latest NFSv4.1 Internet Draft:
16http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-29 21http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-29
@@ -25,6 +30,49 @@ are still under development out of tree.
25See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design 30See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design
26for more information. 31for more information.
27 32
33The current implementation is intended for developers only: while it
34does support ordinary file operations on clients we have tested against
35(including the linux client), it is incomplete in ways which may limit
36features unexpectedly, cause known bugs in rare cases, or cause
37interoperability problems with future clients. Known issues:
38
39 - gss support is questionable: currently mounts with kerberos
40 from a linux client are possible, but we aren't really
41 conformant with the spec (for example, we don't use kerberos
42 on the backchannel correctly).
43 - no trunking support: no clients currently take advantage of
44 trunking, but this is a mandatory failure, and its use is
45 recommended to clients in a number of places. (E.g. to ensure
46 timely renewal in case an existing connection's retry timeouts
47 have gotten too long; see section 8.3 of the draft.)
48 Therefore, lack of this feature may cause future clients to
49 fail.
50 - Incomplete backchannel support: incomplete backchannel gss
51 support and no support for BACKCHANNEL_CTL mean that
52 callbacks (hence delegations and layouts) may not be
53 available and clients confused by the incomplete
54 implementation may fail.
55 - Server reboot recovery is unsupported; if the server reboots,
56 clients may fail.
57 - We do not support SSV, which provides security for shared
58 client-server state (thus preventing unauthorized tampering
59 with locks and opens, for example). It is mandatory for
60 servers to support this, though no clients use it yet.
61 - Mandatory operations which we do not support, such as
62 DESTROY_CLIENTID, FREE_STATEID, SECINFO_NO_NAME, and
63 TEST_STATEID, are not currently used by clients, but will be
64 (and the spec recommends their uses in common cases), and
65 clients should not be expected to know how to recover from the
66 case where they are not supported. This will eventually cause
67 interoperability failures.
68
69In addition, some limitations are inherited from the current NFSv4
70implementation:
71
72 - Incomplete delegation enforcement: if a file is renamed or
73 unlinked, a client holding a delegation may continue to
74 indefinitely allow opens of the file under the old name.
75
28The table below, taken from the NFSv4.1 document, lists 76The table below, taken from the NFSv4.1 document, lists
29the operations that are mandatory to implement (REQ), optional 77the operations that are mandatory to implement (REQ), optional
30(OPT), and NFSv4.0 operations that are required not to implement (MNI) 78(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 |
142 190
143Implementation notes: 191Implementation notes:
144 192
193DELEGPURGE:
194* mandatory only for servers that support CLAIM_DELEGATE_PREV and/or
195 CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that
196 persist across client reboots). Thus we need not implement this for
197 now.
198
145EXCHANGE_ID: 199EXCHANGE_ID:
146* only SP4_NONE state protection supported 200* only SP4_NONE state protection supported
147* implementation ids are ignored 201* implementation ids are ignored