[linux-cifs-client] Re-exporting cifs mount over NFSv4

[Paul "TBBle" Hampson]

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Paul "TBBle" Hampson wrote:
| Paul "TBBle" Hampson wrote:
| | I understood from the git logs and README that the cifs client in
| | 2.6.24 was able to be reexport mounts over NFSv4.

| I discovered the problem. In late October 2007, the exportfs
| interface was changed [1], and cifs was not updated during the
| update. (export.c was last touched non-trivially in early October)

It has been pointed out to me off-list that this was deliberate as
it was actually rather broken.

| cifs currently is missing the one mandatory method fh_to_dentry in
| the export_operations structure, so the exportfs code rejects it as
| an exportable filesystem.

| I dunno if anyone's planning to fix this, I think I'll have a go
| just pointing it at generic_fh_to_dentry (as this seems to be the
| intended behaviour under the old API) and see if that works or if
| it sets our machines on fire.

This turns out to be a non-starter, since we can't look up files in
the filesystem by inode (as far as I can see, UniqueID is only ever
sent by the server, we don't ever ask for a file using it), which
explains the stubby cifs_read_inode (always returns the root inode...)

So I'm not sure how to proceed, in terms of a useful identifier to
encode from the dentry into the filehandle. I'm tempted to try the
full path to the node, but I expect our maxlength will be too short,
and that's pretty nasty.

Anyway, any suggestions here would be greatly appreciated.

- --
- -----------------------------------------------------------
Paul "TBBle" Hampson, B.Sc, LPI, MCSE
Very-later-year Asian Studies student, ANU
The Boss, Bubblesworth Pty Ltd (ABN: 51 095 284 361)
Paul.Hampson at Pobox.com

Of course Pacman didn't influence us as kids. If it did,
we'd be running around in darkened rooms, popping pills and
listening to repetitive music.
~ -- Kristian Wilson, Nintendo, Inc, 1989

License: http://creativecommons.org/licenses/by/2.1/au/
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