[PATCH 2/8] blkcg, writeback: Implement wbc_blkcg_css()

Tejun Heo
2019-06-14T00:34:03Z

Add a helper to determine the target blkcg from wbc.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
include/linux/writeback.h | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index b8f5f000cde4..1c85563f035d 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -93,6 +93,16 @@ static inline int wbc_to_write_flags(struct writeback_control *wbc)
return 0;
}

+static inline struct cgroup_subsys_state *
+wbc_blkcg_css(struct writeback_control *wbc)
+{
+#ifdef CONFIG_CGROUP_WRITEBACK
+ if (wbc->wb)
+ return wbc->wb->blkcg_css;
+#endif
+ return blkcg_root_css;
+}
+
/*
* A wb_domain represents a domain that wb's (bdi_writeback's) belong to
* and are measured against each other in. There always is one global
--
2.17.1