cfq-iosched: fix async queue behaviour

With the cfq_queue hash removal, we inadvertently got rid of the
async queue sharing. This was not intentional, in fact CFQ purposely
shares the async queue per priority level to get good merging for
async writes.

So put some logic in cfq_get_queue() to track the shared queues.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h
index 8e2042b9d471..2eaa142cd061 100644
--- a/include/linux/ioprio.h
+++ b/include/linux/ioprio.h
@@ -47,8 +47,10 @@ enum {
 #define IOPRIO_NORM     (4)
 static inline int task_ioprio(struct task_struct *task)
 {
-        WARN_ON(!ioprio_valid(task->ioprio));
-        return IOPRIO_PRIO_DATA(task->ioprio);
+        if (ioprio_valid(task->ioprio))
+                return IOPRIO_PRIO_DATA(task->ioprio);
+
+        return IOPRIO_NORM;
 }
 
 static inline int task_nice_ioprio(struct task_struct *task)