The 9P2000 protocol requires the authentication and permission checks to be

done in the file server. For that reason every user that accesses the file

server tree has to authenticate and attach to the server separately.

Multiple users can share the same connection to the server.
Currently v9fs does a single attach and executes all I/O operations as a

single user. This makes using v9fs in multiuser environment unsafe as it

depends on the client doing the permission checking.
This patch improves the 9P2000 support by allowing every user to attach

separately. The patch defines three modes of access (new mount option

'access'):
- attach-per-user (access=user)

 If a user tries to access a file served by v9fs for the first time, v9fs

 sends an attach command to the server (Tattach) specifying the user. If

 the attach succeeds, the user can access the v9fs tree.

 As there is no uname->uid (string->integer) mapping yet, this mode works

 only with the 9P2000.u dialect.
- allow only one user to access the tree (access=<uid>)

 Only the user with uid can access the v9fs tree. Other users that attempt

 to access it will get EPERM error.
- do all operations as a single user (access=any)

 V9fs does a single attach and all operations are done as a single user.

 If this mode is selected, the v9fs behavior is identical with the current

 one.
The patch also renames uid and gid options to dfltuid and dfltgid. The new

names describe better the values they set.
Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
---

commit 836f166ce5578b084c1cd75807e29474586bab61

tree c7e1eb631c3e6b0f1cd773ae7884379776c2857d

parent 3ec910913c8c743cbe4cd9cdde17df26a75d02ec

author Latchesar Ionkov <lucho@eregion.(none)> Mon, 03 Sep 2007 14:09:29 -0600

committer Latchesar Ionkov <lucho@eregion.(none)> Mon, 03 Sep 2007 14:09:29 -0600
 fs/9p/fid.c             |  157 +++++++++++++++++++++++++++++++++++++----------

 fs/9p/v9fs.c            |   87 +++++++++++++++++++-------

 fs/9...
[ message continues ]

nit picks:

   * you added/changed options without updated Documentation/filesystems/9p.txt

   * you changed v9fs->extended to be part of a flags structure, that

should have been

       a separate patch
Even small cleanups like this should probably be confined to a
The way the patch got formatted, these look like compulsive

renames..but there's an added function and then changes to the other

two.  I think it might be because of the way you ordered the

functions.  Put new functions after the old functions and maybe this

won't happen.  And clone seems to have lost his function header.  The

code is pretty inconsistent about those these days, but I'd like to do

an audit soon and make sure we have proper comment blocks where

appropriate.
scripts/checkpatch.pl reports:
ERROR: need a space before the open parenthesis '('

#244: FILE: fs/9p/fid.c:147:

+               for(ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
ERROR: need a space before the open parenthesis '('

#275: FILE: fs/9p/fid.c:178:

+       for(d = dentry, i = n; i >= 0; i--, d = d->d_parent)
Please fix up these small bits and resubmit.
                 -eric
Also, go ahead and cc: me directly on patches, for some reason this

one missed my normal filters and got lost.  If I'm directly cc:'d it

will pop to the top of my inbox.
           -eric

-