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

- From: Theodore Ts'o \<hidden\>
- Date: 2015-07-22 03:56:20 
- List: linux-ext4
- Page: https://ratatoskr.run/linux-ext4/2015/07/97843
- Thread: https://ratatoskr.run/cgroups/2015/07/97843/t.md

```text
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 <redacted>
> Cc: "Theodore Ts'o" <redacted>
> Cc: Andreas Dilger <redacted>
> Cc: <redacted>

Thanks, applied.

						- Ted
```