cgroup: Merge branch 'for-4.3-fixes' into for-4.4

Pull to receive 9badce000e2c ("cgroup, writeback: don't enable cgroup
writeback on traditional hierarchies").  The commit adds
cgroup_on_dfl() usages in include/linux/backing-dev.h thus causing a
silent conflict with 9e10a130d9b6 ("cgroup: replace cgroup_on_dfl()
tests in controllers with cgroup_subsys_on_dfl()").  The conflict is
fixed during this merge.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --cc include/linux/backing-dev.h
index 5a5d79ee256f24aa2de8fa92778e8e85cdfcd4b2,d5eb4ad1c534a8074b64ee75d4b597563e36e89a..08d9a8eac42c35fb103747ff105091f4af0f27bd
--- 1/include/linux/backing-dev.h
--- 2/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@@ -258,7 -263,9 +262,9 @@@ static inline bool inode_cgwb_enabled(s
  {
        struct backing_dev_info *bdi = inode_to_bdi(inode);
  
-       return bdi_cap_account_dirty(bdi) &&
 -      return cgroup_on_dfl(mem_cgroup_root_css->cgroup) &&
 -              cgroup_on_dfl(blkcg_root_css->cgroup) &&
++      return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
++              cgroup_subsys_on_dfl(io_cgrp_subsys) &&
+               bdi_cap_account_dirty(bdi) &&
                (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
                (inode->i_sb->s_iflags & SB_I_CGROUPWB);
  }