Re: [PATCH] xfs: speed up directory bestfree block scanning

[Dave Chinner <david@fromorbit.com>]

On Wed, Jan 03, 2018 at 08:28:03AM -0500, Brian Foster wrote:
> On Wed, Jan 03, 2018 at 05:27:48PM +1100, Dave Chinner wrote:
> > +			if (be16_to_cpu(bests[findex]) != NULLDATAOFF &&
> > +			    be16_to_cpu(bests[findex]) >= length) {
> > +				dbno = freehdr.firstdb + findex;
> > +				break;
> >  			}
> > +		} while (++findex < freehdr.nvalid);
> > +
> > +		/* Drop the block if we done with the freeblock */
> 
> "... if we're done ..."
> 
> Also FWIW, according to the comment it looks like the only reason the
> freehdr conversion is elevated to this scope is to accommodate gcc
> foolishness. If so, I'm wondering if a simple NULL init of bests at the
> top of the function would avoid that problem and allow us to move the
> code to where it was apparently intended to be in the first place. Hm?

Yeah, looking at the follow-on patch, there's a gigantic amount of
cleanup needed in this function. There's a bunch of "gcc is so
stupid" hacks amongst the code because the function is too long
for gcc correctly determine variable usage.

I might sit down and factor it properly because that will make it a
whole lot simpler and easier to understand...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com