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

[android-x86/kernel.git] / include / linux / backing-dev.h

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 5a5d79e..08d9a8e 100644 (file)
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -252,13 +252,19 @@ 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_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);
 }