Re: [pnfs] [GIT BISECT] first bad commit: 1f36f774 Switch !O_CREAT case to use of do_last()

Al Viro
2010-03-25T13:06:16Z

On Thu, Mar 25, 2010 at 02:18:56PM +0200, Benny Halevy wrote:

> Indeed this error is coming from the server:
>
> nfsd_dispatch: vers 4 proc 1
> nfsv4 compound op #1/7: 22 (OP_PUTFH)
> nfsd: fh_verify(16: 01010001 00000000 000e6592 345b9f25 00000000 00000000)
> nfsv4 compound op ffff880076734078 opcnt 7 #1: 22: status 0
> nfsv4 compound op #2/7: 32 (OP_SAVEFH)
> nfsv4 compound op ffff880076734078 opcnt 7 #2: 32: status 0
> nfsv4 compound op #3/7: 18 (OP_OPEN)
> NFSD: nfsd4_open filename pack op_stateowner (null)
> renewing client (clientid 4bab503e/00000002)
> nfsd: nfsd_lookup(fh 16: 01010001 00000000 000e6592 345b9f25 00000000 00000000, pack)
> nfsd: fh_verify(16: 01010001 00000000 000e6592 345b9f25 00000000 00000000)
> nfsd: fh_compose(exp 08:05/106497 objects/pack, ino=943508)
> nfsd: fh_verify(16: 01010001 00000000 000e6594 345b9f26 00000000 00000000)
> nfsv4 compound op ffff880076734078 opcnt 7 #3: 18: status 21
> nfsv4 compound returned 21

Ho-hum... So it hits the "let's try to open it atomically" path and
gets told to FOAD by server (as it should, of course).

And if we see different behaviour after ls -l, presumably that's a
difference between ->lookup() and ->d_revalidate() paths on client...

OK, I think I see what's going on in this case. However, it doesn't
explain everything; my current theory is that we used to get LOOKUP_DIRECTORY
on the last components in O_DIRECTORY opens and we don't do that now.
That used to derail the is_atomic_open(), now it's hit and there we go.

It's not hard to verify (and it might take care of this testcase), but
I still have questions about the way this code used to work *without*
O_DIRECTORY.

Let's try this: before do_lookup() call there add
if (*want_dir)
nd->flags |= LOOKUP_DIRECTORY;
and see how does it behave.

However, even if it does help, it doesn't explain everything. Normal
open() on a directory without O_DIRECTORY if flags shouldn't fail with
-EISDIR. How did that manage to avoid it all along?