const: mark remaining export_operations const

[pandora-kernel.git] / fs / fs-writeback.c

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 3475775..8e1e5e1 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -97,6 +97,11 @@ static void bdi_work_clear(struct bdi_work *work)
 {
        clear_bit(WS_USED_B, &work->state);
        smp_mb__after_clear_bit();
+       /*
+        * work can have disappeared at this point. bit waitq functions
+        * should be able to tolerate this, provided bdi_sched_wait does
+        * not dereference it's pointer argument.
+       */
        wake_up_bit(&work->state, WS_USED_B);
 }
 
@@ -113,6 +118,7 @@ static void bdi_work_free(struct rcu_head *head)
 static void wb_work_complete(struct bdi_work *work)
 {
        const enum writeback_sync_modes sync_mode = work->args.sync_mode;
+       int onstack = bdi_work_on_stack(work);
 
        /*
         * For allocated work, we can clear the done/seen bit right here.
@@ -120,9 +126,9 @@ static void wb_work_complete(struct bdi_work *work)
         * to after the RCU grace period, since the stack could be invalidated
         * as soon as bdi_work_clear() has done the wakeup.
         */
-       if (!bdi_work_on_stack(work))
+       if (!onstack)
                bdi_work_clear(work);
-       if (sync_mode == WB_SYNC_NONE || bdi_work_on_stack(work))
+       if (sync_mode == WB_SYNC_NONE || onstack)
                call_rcu(&work->rcu_head, bdi_work_free);
 }
 
@@ -151,10 +157,10 @@ static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work)
        BUG_ON(!bdi->wb_cnt);
 
        /*
-        * Make sure stores are seen before it appears on the list
+        * list_add_tail_rcu() contains the necessary barriers to
+        * make sure the above stores are seen before the item is
+        * noticed on the list
         */
-       smp_mb();
-
        spin_lock(&bdi->wb_lock);
        list_add_tail_rcu(&work->list, &bdi->work_list);
        spin_unlock(&bdi->wb_lock);
@@ -168,13 +174,7 @@ static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work)
        else {
                struct bdi_writeback *wb = &bdi->wb;
 
-               /*
-                * End work now if this wb has no dirty IO pending. Otherwise
-                * wakeup the handling thread
-                */
-               if (!wb_has_dirty_io(wb))
-                       wb_clear_pending(wb, work);
-               else if (wb->task)
+               if (wb->task)
                        wake_up_process(wb->task);
        }
 }
@@ -772,8 +772,9 @@ static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi,
        rcu_read_lock();
 
        list_for_each_entry_rcu(work, &bdi->work_list, list) {
-               if (!test_and_clear_bit(wb->nr, &work->seen))
+               if (!test_bit(wb->nr, &work->seen))
                        continue;
+               clear_bit(wb->nr, &work->seen);
 
                ret = work;
                break;