Re: [PATCH 4/3] Avoid using 'lstat()' to figure out directories

[Linus Torvalds <torvalds@linux-foundation.org>]

On Fri, 10 Jul 2009, Paolo Bonzini wrote:
> 
> I'm not much worried about accessing foo-0001, foo-0002, foo-0003 while 
> looking for foo/a (that would be O(number of files in a directory), 
> which is bearable), but risking to go down a huge subtree is not very 
> nice.

That sounds rather unlikely, and the thing is, even if it were to happen, 
it really wouldn't be that slow. Our data structures are pretty efficient, 
and it wouldn't be _that_ slow to traverse them.

That said, I don't love that loop. It would be better to do that whole 
cache_name_pos() call with the '/' simply appended to the path, and then 
we'd do the binary search directly to the first entry.

Of course, since 'path' is a 'const char *', we'd need to either do a 
silly copy, or we'd need to change a whole lot of the code to make it 
clear that we can actually add a slash to the end (which we can: I think 
it's already always going to be an array that we _will_ add a slash to in 
case it turns out to be a directory).

So there's definitely room for improvement there. I just think that the 
improvement isn't the patch you suggest.

			Linus