Merge remote-tracking branch 'ext4/dev'

[karo-tx-linux.git] / fs / fs-writeback.c

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 091a36444972fa0b746118b0cc58ca2a3dcaa97f..7378169e90be6ed485ac48d0cf633c8e37c4c3d2 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -778,19 +778,24 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
                                  struct wb_writeback_work *base_work,
                                  bool skip_if_busy)
 {
-       int next_memcg_id = 0;
-       struct bdi_writeback *wb;
-       struct wb_iter iter;
+       struct bdi_writeback *last_wb = NULL;
+       struct bdi_writeback *wb = list_entry(&bdi->wb_list,
+                                             struct bdi_writeback, bdi_node);
 
        might_sleep();
 restart:
        rcu_read_lock();
-       bdi_for_each_wb(wb, bdi, &iter, next_memcg_id) {
+       list_for_each_entry_continue_rcu(wb, &bdi->wb_list, bdi_node) {
                DEFINE_WB_COMPLETION_ONSTACK(fallback_work_done);
                struct wb_writeback_work fallback_work;
                struct wb_writeback_work *work;
                long nr_pages;
 
+               if (last_wb) {
+                       wb_put(last_wb);
+                       last_wb = NULL;
+               }
+
                /* SYNC_ALL writes out I_DIRTY_TIME too */
                if (!wb_has_dirty_io(wb) &&
                    (base_work->sync_mode == WB_SYNC_NONE ||
@@ -819,12 +824,22 @@ restart:
 
                wb_queue_work(wb, work);
 
-               next_memcg_id = wb->memcg_css->id + 1;
+               /*
+                * Pin @wb so that it stays on @bdi->wb_list.  This allows
+                * continuing iteration from @wb after dropping and
+                * regrabbing rcu read lock.
+                */
+               wb_get(wb);
+               last_wb = wb;
+
                rcu_read_unlock();
                wb_wait_for_completion(bdi, &fallback_work_done);
                goto restart;
        }
        rcu_read_unlock();
+
+       if (last_wb)
+               wb_put(last_wb);
 }
 
 #else  /* CONFIG_CGROUP_WRITEBACK */
@@ -1857,12 +1872,11 @@ void wakeup_flusher_threads(long nr_pages, enum wb_reason reason)
        rcu_read_lock();
        list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
                struct bdi_writeback *wb;
-               struct wb_iter iter;
 
                if (!bdi_has_dirty_io(bdi))
                        continue;
 
-               bdi_for_each_wb(wb, bdi, &iter, 0)
+               list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node)
                        wb_start_writeback(wb, wb_split_bdi_pages(wb, nr_pages),
                                           false, reason);
        }
@@ -1894,11 +1908,10 @@ static void wakeup_dirtytime_writeback(struct work_struct *w)
        rcu_read_lock();
        list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
                struct bdi_writeback *wb;
-               struct wb_iter iter;
 
-               bdi_for_each_wb(wb, bdi, &iter, 0)
-                       if (!list_empty(&bdi->wb.b_dirty_time))
-                               wb_wakeup(&bdi->wb);
+               list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node)
+                       if (!list_empty(&wb->b_dirty_time))
+                               wb_wakeup(wb);
        }
        rcu_read_unlock();
        schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ);