[PATCH 21/24] blkcg: make blkcg_print_blkgs() grab q locks instead of blkcg lock

[Vivek Goyal]

On Fri, Dec 28, 2012 at 12:35:43PM -0800, Tejun Heo wrote:
> Instead of holding blkcg->lock while walking ->blkg_list and executing
> prfill(), RCU walk ->blkg_list and hold the blkg's queue lock while
> executing prfill().  This makes prfill() implementations easier as
> stats are mostly protected by queue lock.
> 
> This will be used to implement hierarchical stats.
> 
> Signed-off-by: Tejun Heo <tj at kernel.org>

Acked-by: Vivek Goyal <vgoyal at redhat.com>

Vivek