Re: [PATCH 2/2] ext4: implement cgroup writeback support

[Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>]

On Tue, Jun 16, 2015 at 06:53:13PM -0400, Tejun Heo wrote:
> For ordered and writeback data modes, all data IOs go through
> ext4_io_submit.  This patch adds cgroup writeback support by invoking
> wbc_init_bio() from io_submit_init_bio() and wbc_account_io() in
> io_submit_add_bh().  Journal data which is written by jbd2 worker is
> left alone by this patch and will always be written out from the root
> cgroup.
> 
> ext4_fill_super() is updated to set MS_CGROUPWB when data mode is
> either ordered or writeback.  In journaled data mode, most IOs become
> synchronous through the journal and enabling cgroup writeback support
> doesn't make much sense or difference.  Journaled data mode is left
> alone.
> 
> Lightly tested with sequential data write workload.  Behaves as
> expected.
> 
> v2: Updated for MS_CGROUPWB -> SB_I_CGROUPWB.
> 
> Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: "Theodore Ts'o" <tytso-3s7WtUTddSA@public.gmane.org>
> Cc: Andreas Dilger <adilger.kernel-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>
> Cc: linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

Thanks, applied.

						- Ted