tree db9ab2c70fdeb030c26dfdab44bb79ed231be407
parent 2923e99024480d54fd70b14de3a755f68c9da4d2
author Tejun Heo <tj@kernel.org> 1507653713 -0700
committer Tejun Heo <tj@kernel.org> 1507653719 -0700

btrfs: ensure that metadata and flush are issued from the root cgroup

Issuing metdata or otherwise shared IOs from !root cgroup can lead to
priority inversion.  This patch ensures that those IOs are always
issued from the root cgroup.

This patch updates btrfs_update_iflags() to not set S_CGROUPWB on
btree_inodes.  This isn't strictly necessary as those inodes don't
call the function during init; however, this serves as documentation
and prevents possible future mistakes.  If this isn't desirable,
please feel free to drop the section.

v2: Fixed missing @bh in submit_bh_blkcg_css() call.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>