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

[Al Viro <viro@ZenIV.linux.org.uk>]

On Thu, Mar 25, 2010 at 03:52:25PM +0200, Benny Halevy wrote:
> On Mar. 25, 2010, 15:37 +0200, Al Viro <viro@ZenIV.linux.org.uk> wrote:
> > On Thu, Mar 25, 2010 at 03:30:22PM +0200, Boaz Harrosh wrote:
> >>> Let's try this: before do_lookup() call there add
> >>> 	if (*want_dir)
> >>> 		nd->flags |= LOOKUP_DIRECTORY;
> >> Yes this fixes it!!
> >> 2.6.34-rc2 plus above, now works, horay. (diff attached)
> >>
> >>> 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?
> > 
> > Does open() of directory _without_ O_DIRECTORY work in e.g. vanilla 2.6.33?
> > It certainly does for local filesystems and it does for NFSv3; does it work
> > for NFSv4?
> 
> No, it doesn't.
> 
> # mount localhost:/usr0/nfs4export /mnt/localhost; strace cat /mnt/localhost/server 2>&1 | grep 'open.*server'; umount /mnt/localhost
> open("/mnt/localhost/server", O_RDONLY) = 3
> 
> # mount -t nfs4 localhost:/ /mnt/localhost; strace cat /mnt/localhost/server 2>&1 | grep 'open.*server'; umount /mnt/localhost
> open("/mnt/localhost/server", O_RDONLY) = -1 EISDIR (Is a directory)

Gets better - if you do ls -l /mnt/localhost/server and then repeat that
open(), it'll succeed.