Re: [heads-up] mknod() broken on nfs4

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

On Thu, Jun 23, 2011 at 12:19:46AM +0100, Al Viro wrote:
> It always worked that way, all the way back to Unix v6 (and I'm fairly sure
> to earlier than that; don't have v5 kernel source, unfortunately).  Worked
> that way in Linux since 0.02/0.03/0.10, when Linus first added mknod(2)
> (presumably 0.01 had been tested with /dev populated by Minix ;-)
> 
> As for POSIX, what it says is
>      The only portable use of mknod() is to create a FIFO-special file.         
>      If mode is not S_IFIFO or dev is not 0, the behaviour of mknod() is        
>      unspecified.                                                               
> and we support it for all non-directories.  Always had...
> 
> 	Note that the right thing to do is to issue CLOSE and _not_ call
> lookup_instantiate_filp() if we are called from sys_mknodat().  We don't
> want to leak stateid...

OK...  See #untested in vfs-2.6.git; the last 5 commits there.  The actual
fixes are in the last one; to get rid of the dependency on the previous
we'd just need to pass open_flags as additional argument to
nameidata_to_nfs_open_context() (like untested@{1}, but without removal
of nameidata argument - that part depends on earlier commits and is, IMO,
a good idea anyway).

It seems to work here.  Testing and comments would be welcome...