block: add io_context->active_ref

[~andy/linux] / block / blk-ioc.c

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 10928740b5dab4366ba6fb728b0a54cf16a41275..439ec21fd787eea2b71fdc798046c392ee96e284 100644 (file)
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -149,20 +149,20 @@ void put_io_context(struct io_context *ioc)
 }
 EXPORT_SYMBOL(put_io_context);
 
-/* Called by the exiting task */
-void exit_io_context(struct task_struct *task)
+/**
+ * put_io_context_active - put active reference on ioc
+ * @ioc: ioc of interest
+ *
+ * Undo get_io_context_active().  If active reference reaches zero after
+ * put, @ioc can never issue further IOs and ioscheds are notified.
+ */
+void put_io_context_active(struct io_context *ioc)
 {
-       struct io_context *ioc;
-       struct io_cq *icq;
        struct hlist_node *n;
        unsigned long flags;
+       struct io_cq *icq;
 
-       task_lock(task);
-       ioc = task->io_context;
-       task->io_context = NULL;
-       task_unlock(task);
-
-       if (!atomic_dec_and_test(&ioc->nr_tasks)) {
+       if (!atomic_dec_and_test(&ioc->active_ref)) {
                put_io_context(ioc);
                return;
        }
@@ -191,6 +191,20 @@ retry:
        put_io_context(ioc);
 }
 
+/* Called by the exiting task */
+void exit_io_context(struct task_struct *task)
+{
+       struct io_context *ioc;
+
+       task_lock(task);
+       ioc = task->io_context;
+       task->io_context = NULL;
+       task_unlock(task);
+
+       atomic_dec(&ioc->nr_tasks);
+       put_io_context_active(ioc);
+}
+
 /**
  * ioc_clear_queue - break any ioc association with the specified queue
  * @q: request_queue being cleared
@@ -223,7 +237,7 @@ int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
 
        /* initialize */
        atomic_long_set(&ioc->refcount, 1);
-       atomic_set(&ioc->nr_tasks, 1);
+       atomic_set(&ioc->active_ref, 1);
        spin_lock_init(&ioc->lock);
        INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH);
        INIT_HLIST_HEAD(&ioc->icq_list);