Re: ENOSPC returned during writepages

[Theodore Tso <tytso@mit.edu>]

On Wed, Aug 20, 2008 at 01:56:48PM -0700, Mingming Cao wrote:
> > BTW, I was looking at the percpu_counter interface, and I'm confused
> > why we have percpu_counter_sum_and_set() and percpu_counter_sum().  If
> > we're taking the fbc->lock to calculate the precise value of the
> > counter, why not simply set fbc->count?  
> 
> I added the percpu_count_sum_and _set() interface, when addingdelalloc
> block reservation. I agree it make sense to clean up current all the
> user of percpu_counter_sum() and replace with
> percpu_counter_sum_and_set(), just hasn't get chance to clean up yet.

Why not make percpu_counter_sum() always do sum_and_set, and change
the ext4 calls to use percpu_counter_sum()?  In fact, I'm wondering
why you didn't do that in the first place?  Was that your trying to be
as conservative as possible with respect to not changing things?

   		   	    	 	    - Ted