writeback: bdi_writeback iteration must not skip dying ones

[linux-2.6-block.git] / include / linux / backing-dev.h

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 5a5d79ee256f24aa2de8fa92778e8e85cdfcd4b2..78677e5a65bf12d7620211ded4d086f435559f6f 100644 (file)
--- 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);
 }
@@ -401,61 +408,6 @@ static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
        rcu_read_unlock();
 }
 
-struct wb_iter {
-       int                     start_memcg_id;
-       struct radix_tree_iter  tree_iter;
-       void                    **slot;
-};
-
-static inline struct bdi_writeback *__wb_iter_next(struct wb_iter *iter,
-                                                  struct backing_dev_info *bdi)
-{
-       struct radix_tree_iter *titer = &iter->tree_iter;
-
-       WARN_ON_ONCE(!rcu_read_lock_held());
-
-       if (iter->start_memcg_id >= 0) {
-               iter->slot = radix_tree_iter_init(titer, iter->start_memcg_id);
-               iter->start_memcg_id = -1;
-       } else {
-               iter->slot = radix_tree_next_slot(iter->slot, titer, 0);
-       }
-
-       if (!iter->slot)
-               iter->slot = radix_tree_next_chunk(&bdi->cgwb_tree, titer, 0);
-       if (iter->slot)
-               return *iter->slot;
-       return NULL;
-}
-
-static inline struct bdi_writeback *__wb_iter_init(struct wb_iter *iter,
-                                                  struct backing_dev_info *bdi,
-                                                  int start_memcg_id)
-{
-       iter->start_memcg_id = start_memcg_id;
-
-       if (start_memcg_id)
-               return __wb_iter_next(iter, bdi);
-       else
-               return &bdi->wb;
-}
-
-/**
- * bdi_for_each_wb - walk all wb's of a bdi in ascending memcg ID order
- * @wb_cur: cursor struct bdi_writeback pointer
- * @bdi: bdi to walk wb's of
- * @iter: pointer to struct wb_iter to be used as iteration buffer
- * @start_memcg_id: memcg ID to start iteration from
- *
- * Iterate @wb_cur through the wb's (bdi_writeback's) of @bdi in ascending
- * memcg ID order starting from @start_memcg_id.  @iter is struct wb_iter
- * to be used as temp storage during iteration.  rcu_read_lock() must be
- * held throughout iteration.
- */
-#define bdi_for_each_wb(wb_cur, bdi, iter, start_memcg_id)             \
-       for ((wb_cur) = __wb_iter_init(iter, bdi, start_memcg_id);      \
-            (wb_cur); (wb_cur) = __wb_iter_next(iter, bdi))
-
 #else  /* CONFIG_CGROUP_WRITEBACK */
 
 static inline bool inode_cgwb_enabled(struct inode *inode)
@@ -515,14 +467,6 @@ static inline void wb_blkcg_offline(struct blkcg *blkcg)
 {
 }
 
-struct wb_iter {
-       int             next_id;
-};
-
-#define bdi_for_each_wb(wb_cur, bdi, iter, start_blkcg_id)             \
-       for ((iter)->next_id = (start_blkcg_id);                        \
-            ({ (wb_cur) = !(iter)->next_id++ ? &(bdi)->wb : NULL; }); )
-
 static inline int inode_congested(struct inode *inode, int cong_bits)
 {
        return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);