blkcg, writeback: Add wbc->no_cgroup_owner (27b36d8f) · Commits · 戴 / test

When writeback IOs are bounced through async layers, the IOs should only be accounted against the wbc from the original bdi writeback to avoid confusing cgroup inode ownership arbitration. Add wbc->no_cgroup_owner to allow disabling wbc cgroup owner accounting. This will be used make btrfs compression work well with cgroup IO control. v2: Renamed from no_wbc_acct to no_cgroup_owner and added comment as per Jan. Reviewed-by:

Josef Bacik <josef@toxicpanda.com> Reviewed-by:

Jan Kara <jack@suse.cz> Signed-off-by:

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

Jens Axboe <axboe@kernel.dk>

fs/fs-writeback.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -727,7 +727,7 @@ void wbc_account_cgroup_owner(struct writeback_control wbc, struct page page,
		* behind a slow cgroup. Ultimately, we want pageout() to kick off
		* regular writeback instead of writing things out itself.
		*/
		if (!wbc->wb)
		if (!wbc->wb \|\| wbc->no_cgroup_owner)
		return;

		css = mem_cgroup_css_from_page(page);

include/linux/writeback.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -68,6 +68,15 @@ struct writeback_control {
		unsigned for_reclaim:1; /* Invoked from the page allocator */
		unsigned range_cyclic:1; /* range_start is cyclic */
		unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */

		/*
		* When writeback IOs are bounced through async layers, only the
		* initial synchronous phase should be accounted towards inode
		* cgroup ownership arbitration to avoid confusion. Later stages
		* can set the following flag to disable the accounting.
		*/
		unsigned no_cgroup_owner:1;

		#ifdef CONFIG_CGROUP_WRITEBACK
		struct bdi_writeback wb; / wb this writeback is issued under */
		struct inode inode; / inode being written out */

Admin message