Re: [PATCH vfs-2.6:for-next] vfs: remount_fs BKL pushdown

Al Viro
2009-05-06T03:52:01Z

On Tue, May 05, 2009 at 04:43:52PM -0400, Christoph Hellwig wrote:
> On Tue, May 05, 2009 at 09:39:38PM +0200, Alessio Igor Bogani wrote:
> > >> Please also push down lock_super, no need to have two locking changes in
> > >> this area just after another.
> > >
> > > Do you plan to do that respin? ?I will need the lock_super pushdown for
> > > some sync work. ?I can wait for you if you plan to submit it, otherwise
> > > I'll out it on my TODO list.
> >
> > Apologize I have completely missed your first replay.
> >
> > Let me two days for finish that task and for do build and boot tests.
>
> Great! Thanks a lot for the effort.

Actually, I'm not sure that you are right. Especially if we go for your
"always hold s_umount for sync_filesystem()"; in that case we are guaranteed
that we'll have an exclusion between ->write_super() and that sucker, so
there's no reason to push it down into filesystems that do not use lock_super()
at all. And that'd be most of them...

Note that I've taken all callers of remount under exclusive s_umount (see
#untested in the vfs tree).