1 files changed, 59 insertions, 1 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 0910a5584d38..c04d16b02225 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -289,7 +289,6 @@ void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags,
                 kmem_cache_free(iocontext_cachep, ioc);
         task_unlock(task);
 }
-EXPORT_SYMBOL(create_io_context_slowpath);
 
 /**
  * get_task_io_context - get io_context of a task
@@ -362,6 +361,65 @@ out:
 }
 EXPORT_SYMBOL(ioc_lookup_icq);
 
+/**
+ * ioc_create_icq - create and link io_cq
+ * @q: request_queue of interest
+ * @gfp_mask: allocation mask
+ *
+ * Make sure io_cq linking %current->io_context and @q exists.  If either
+ * io_context and/or icq don't exist, they will be created using @gfp_mask.
+ *
+ * The caller is responsible for ensuring @ioc won't go away and @q is
+ * alive and will stay alive until this function returns.
+ */
+struct io_cq *ioc_create_icq(struct request_queue *q, gfp_t gfp_mask)
+{
+        struct elevator_type *et = q->elevator->type;
+        struct io_context *ioc;
+        struct io_cq *icq;
+
+        /* allocate stuff */
+        ioc = create_io_context(current, gfp_mask, q->node);
+        if (!ioc)
+                return NULL;
+
+        icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO,
+                                    q->node);
+        if (!icq)
+                return NULL;
+
+        if (radix_tree_preload(gfp_mask) < 0) {
+                kmem_cache_free(et->icq_cache, icq);
+                return NULL;
+        }
+
+        icq->ioc = ioc;
+        icq->q = q;
+        INIT_LIST_HEAD(&icq->q_node);
+        INIT_HLIST_NODE(&icq->ioc_node);
+
+        /* lock both q and ioc and try to link @icq */
+        spin_lock_irq(q->queue_lock);
+        spin_lock(&ioc->lock);
+
+        if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) {
+                hlist_add_head(&icq->ioc_node, &ioc->icq_list);
+                list_add(&icq->q_node, &q->icq_list);
+                if (et->ops.elevator_init_icq_fn)
+                        et->ops.elevator_init_icq_fn(icq);
+        } else {
+                kmem_cache_free(et->icq_cache, icq);
+                icq = ioc_lookup_icq(ioc, q);
+                if (!icq)
+                        printk(KERN_ERR "cfq: icq link failed!\n");
+        }
+
+        spin_unlock(&ioc->lock);
+        spin_unlock_irq(q->queue_lock);
+        radix_tree_preload_end();
+        return icq;
+}
+
 void ioc_set_changed(struct io_context *ioc, int which)
 {
         struct io_cq *icq;