Re: + fs-introduce-write_begin-write_end-and-perform_write-aops.patch added to -mm tree

[Nick Piggin <npiggin@suse.de>]

On Thu, Jun 14, 2007 at 11:52:49AM +0200, Jan Kara wrote:
> > On Wed, 2007-06-13 at 13:43 +0200, Nick Piggin wrote:
> > ..
> > >  
> > > > 5) ext3_write_end:
> > > > 	Before  write_begin/write_end patch set we have folowing locking
> > > > 	order:
> > > > 		stop_journal(handle);
> > > > 		unlock_page(page);
> > > > 	But now order is oposite:
> > > > 		unlock_page(page);
> > > > 		stop_journal(handle);
> > > > 	Can we got any race condition now? I'm not sure is it actual problem,
> > > > 	may be somebody cant describe this.
> > > 
> > > Can we just change it to the original order? That would seem to be
> > > safest unless one of the ext3 devs explicitly acks it.
>   Sorry, I've missed beginning of this thread. But what problems can
> exactly cause this ordering change? ext3_journal_stop has no need to be
> protected by the page lock - it can be even better that it's not
> protected as it can trigger commit and all that would happen
> unnecessarily under page lock...

Sure, if you think it is safe. I would rather it be done in a
different patch though.