Re: mkstemp fails on cifs linux-2.6.31-rc1 / samba-3.3.6

On Wed, 2009-07-01 at 08:17 -0500, Shirish Pargaonkar wrote:
> On Wed, Jul 1, 2009 at 7:13 AM, Jeff Layton<[email protected]> wrote:
> > On Wed, 2009-07-01 at 06:59 -0500, Shirish Pargaonkar wrote:
> >> On Wed, Jul 1, 2009 at 6:21 AM, Jeff Layton<[email protected]> 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 <[email protected]>
> >> >
> >>
> >> 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
> >
> > Right, but do we really need to do the lookup in that case? It seems
> > like the old check didn't optimize it away (but maybe I'm remembering
> > incorrectly).
> >
> > --
> > Jeff Layton <[email protected]>
> >
> >
> 
> With the check, we are back to what was before lookup intent for
> exclusive create.  I think for exclusive create, a lookup can result in
> not create if the file exists, so for a command like mktemp, it
> probably does not help, there will be a lookup and there will be a create.

I'm sorry, I don't understand what you're saying here. Can you rephrase
it? Or better yet, maybe post the patch that you're proposing to fix
this?

-- 
Jeff Layton <[email protected]>