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-rw-r--r--include/linux/backing-dev.h11
1 files changed, 9 insertions, 2 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 5a5d79ee256f..d5eb4ad1c534 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -13,6 +13,7 @@
#include <linux/sched.h>
#include <linux/blkdev.h>
#include <linux/writeback.h>
+#include <linux/memcontrol.h>
#include <linux/blk-cgroup.h>
#include <linux/backing-dev-defs.h>
#include <linux/slab.h>
@@ -252,13 +253,19 @@ int inode_congested(struct inode *inode, int cong_bits);
* @inode: inode of interest
*
* cgroup writeback requires support from both the bdi and filesystem.
- * Test whether @inode has both.
+ * Also, both memcg and iocg have to be on the default hierarchy. Test
+ * whether all conditions are met.
+ *
+ * Note that the test result may change dynamically on the same inode
+ * depending on how memcg and iocg are configured.
*/
static inline bool inode_cgwb_enabled(struct inode *inode)
{
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) &&
+ bdi_cap_account_dirty(bdi) &&
(bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
(inode->i_sb->s_iflags & SB_I_CGROUPWB);
}