Re: [patch 1/2] fs: cleanup files_lock

[Nick Piggin <npiggin@suse.de>]

On Wed, Mar 17, 2010 at 07:16:02AM -0700, Greg KH wrote:
> On Tue, Mar 16, 2010 at 08:44:23PM +1100, Nick Piggin wrote:
> > I would like to start sending bits of vfs scalability improvements to
> > be reviewed and hopefully merged.
> > 
> > I will start with files_lock. Last time this one came up, it was
> > criticised because some hoped to get rid of files list, and because
> > it didn't have enough justification of the scalability improvement.
> > 
> > For the first criticism, it isn't any more difficult to rip out if
> > we are ever able to remove files list. For the second, I have gathered
> > some statistics and written better justification. Andi I believe is
> > finding kbuild is becoming limited by files lock on larger systems.
> > 
> > --
> > 
> > fs: cleanup files_lock
> > 
> > Lock tty_files with a new spinlock, tty_files_lock; provide helpers to
> > manipulate the per-sb files list; unexport the files_lock spinlock.
> > 
> > Signed-off-by: Nick Piggin <npiggin@suse.de>
> 
> Looks good to me.

So long as the tty file always gets removed before file_sb_list_del
in __fput or put_filp. Otherwise file_sb_list_del would use the wrong
lock for it. As far as I could see, it should always get removed by
tty_release.


>  Do you want me to apply this to my tty tree, or do
> you want to take it through your tree because your other patch depends
> on this?
> 
> If you want to do it, feel free to add:
> 	Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
> to the patch.

If they aren't both applied to -vfs tree in this round I'll ask you to
apply this one.

Thanks,
Nick