Re: Build failure with latest -git: btrfs on ppc64

[Chris Mason <chris.mason@oracle.com>]

On Mon, 2009-02-09 at 10:57 -0500, Kyle McMartin wrote:
> On Mon, Feb 09, 2009 at 09:57:26AM -0500, Chris Mason wrote:
> > 
> > Ok, I thought this would be defined to something simple for the
> > non-ticket users, should I just not be using this call?  
> > 
> 
> I think the use is fine, since it's really a judgement call based on
> whether there's waiters for the ticket. I need to take a closer look
> at where this is used to say...
> 

The Btrfs use goes something like this:

I'm about to wait for the disk.  If there are other procs waiting for
the locks I'm holding, I'll drop my locks and do a somewhat expensive
btree search over again later so the waiters can make progress.

If nobody is waiting, I'll do my read with my locks held so that I don't
have to search again.

> It's inevitable for you to hit things like this though, as far as I know
> you're the first user of this lock interface. :)

;)

-chris