ioprio: move io priority from task_struct to io_context

This is where it belongs and then it doesn't take up space for a
process that doesn't do IO.

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

1 files changed, 21 insertions, 8 deletions

diff --git a/fs/ioprio.c b/fs/ioprio.c
index e4e01bc7f338..a7600401ecf7 100644
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -41,18 +41,29 @@ 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;
+                ioc->task = task;
+        } 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 +159,9 @@ 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;
 }