io context sharing: preliminary support

[linux-2.6-omap-h63xx.git] / fs / ioprio.c

diff --git a/fs/ioprio.c b/fs/ioprio.c
index e4e01bc7f3387daf2b9282a4ec614a50b5955190..06b5d97c5fddfe5a0edccebb215d90050fb65e43 100644 (file)
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -41,18 +41,28 @@ static int set_task_ioprio(struct task_struct *task, int ioprio)
                return err;
 
        task_lock(task);
+       do {
+               ioc = task->io_context;
+               /* see wmb() in current_io_context() */
+               smp_read_barrier_depends();
+               if (ioc)
+                       break;
 
-       task->ioprio = ioprio;
-
-       ioc = task->io_context;
-       /* see wmb() in current_io_context() */
-       smp_read_barrier_depends();
+               ioc = alloc_io_context(GFP_ATOMIC, -1);
+               if (!ioc) {
+                       err = -ENOMEM;
+                       break;
+               }
+               task->io_context = ioc;
+       } while (1);
 
-       if (ioc)
+       if (!err) {
+               ioc->ioprio = ioprio;
                ioc->ioprio_changed = 1;
+       }
 
        task_unlock(task);
-       return 0;
+       return err;
 }
 
 asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
@@ -148,7 +158,9 @@ static int get_task_ioprio(struct task_struct *p)
        ret = security_task_getioprio(p);
        if (ret)
                goto out;
-       ret = p->ioprio;
+       ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
+       if (p->io_context)
+               ret = p->io_context->ioprio;
 out:
        return ret;
 }