[linux-cifs-client] mkstemp fails on cifs linux-2.6.31-rc1 / samba-3.3.6

[Shirish Pargaonkar]

On Wed, Jul 1, 2009 at 6:21 AM, Jeff Layton<jlayton at redhat.com> wrote:
> On Wed, 2009-07-01 at 06:01 -0500, Shirish Pargaonkar wrote:
>>
>> I think the problem is, why EEXIST since file does not exist.  The
>> looping is I guess
>> because mktemp then attempts to create another file and receives EEXIST and it
>> goes on forever.
>> So the basic issues is why EEXIST since mktemp is attempting a file
>> which does not
>> exist on the server.
>
> The problem is that the lookup is returning a positive dentry since it
> just created the file. This makes the VFS turn around and return -EEXIST
> (see the second O_EXCL check in do_filp_open). So we do have to skip the
> create on lookup for O_EXCL or it won't work.
>
> I think what's needed is something like this patch. It seems to fix the
> testcase for me. That said, this is not adequately regression tested and
> should not be committed until it is.
>
> On that note, I'd like to reiterate my earlier sentiment that all of
> this create-on-lookup code was committed prematurely and should be
> backed out until it's more fully baked.
>
> Just my USD$.02...
>
> --
> Jeff Layton <jlayton at redhat.com>
>

meant to send this to everybody but ended up sending only to Jeff,
so here it is again...

I think that is why it is not possible to exclusive create within
lookup intent code.
So, IMHO, we should put the check back in the cifs_lookup.
That is what NFS does, and cifs should do the same