/*
* fs/ioprio.c
*
- * Copyright (C) 2004 Jens Axboe <axboe@suse.de>
+ * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
*
* Helper functions for setting/querying io priorities of processes. The
* system calls closely mimmick getpriority/setpriority, see the man page for
task->ioprio = ioprio;
ioc = task->io_context;
- if (ioc && ioc->set_ioprio)
- ioc->set_ioprio(ioc, ioprio);
+ /* see wmb() in current_io_context() */
+ smp_read_barrier_depends();
+
+ if (ioc)
+ ioc->ioprio_changed = 1;
task_unlock(task);
return 0;
int data = IOPRIO_PRIO_DATA(ioprio);
struct task_struct *p, *g;
struct user_struct *user;
+ struct pid *pgrp;
int ret;
switch (class) {
}
ret = -ESRCH;
- read_lock_irq(&tasklist_lock);
+ /*
+ * We want IOPRIO_WHO_PGRP/IOPRIO_WHO_USER to be "atomic",
+ * so we can't use rcu_read_lock(). See re-copy of ->ioprio
+ * in copy_process().
+ */
+ read_lock(&tasklist_lock);
switch (which) {
case IOPRIO_WHO_PROCESS:
if (!who)
break;
case IOPRIO_WHO_PGRP:
if (!who)
- who = process_group(current);
- do_each_task_pid(who, PIDTYPE_PGID, p) {
+ pgrp = task_pgrp(current);
+ else
+ pgrp = find_pid(who);
+ do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
ret = set_task_ioprio(p, ioprio);
if (ret)
break;
- } while_each_task_pid(who, PIDTYPE_PGID, p);
+ } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
break;
case IOPRIO_WHO_USER:
if (!who)
continue;
ret = set_task_ioprio(p, ioprio);
if (ret)
- break;
+ goto free_uid;
} while_each_thread(g, p);
-
+free_uid:
if (who)
free_uid(user);
break;
ret = -EINVAL;
}
- read_unlock_irq(&tasklist_lock);
+ read_unlock(&tasklist_lock);
return ret;
}
return ret;
}
+int ioprio_best(unsigned short aprio, unsigned short bprio)
+{
+ unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
+ unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
+
+ if (aclass == IOPRIO_CLASS_NONE)
+ aclass = IOPRIO_CLASS_BE;
+ if (bclass == IOPRIO_CLASS_NONE)
+ bclass = IOPRIO_CLASS_BE;
+
+ if (aclass == bclass)
+ return min(aprio, bprio);
+ if (aclass > bclass)
+ return bprio;
+ else
+ return aprio;
+}
+
asmlinkage long sys_ioprio_get(int which, int who)
{
struct task_struct *g, *p;
struct user_struct *user;
+ struct pid *pgrp;
int ret = -ESRCH;
int tmpio;
- read_lock_irq(&tasklist_lock);
+ read_lock(&tasklist_lock);
switch (which) {
case IOPRIO_WHO_PROCESS:
if (!who)
break;
case IOPRIO_WHO_PGRP:
if (!who)
- who = process_group(current);
- do_each_task_pid(who, PIDTYPE_PGID, p) {
+ pgrp = task_pgrp(current);
+ else
+ pgrp = find_pid(who);
+ do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
tmpio = get_task_ioprio(p);
if (tmpio < 0)
continue;
ret = tmpio;
else
ret = ioprio_best(ret, tmpio);
- } while_each_task_pid(who, PIDTYPE_PGID, p);
+ } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
break;
case IOPRIO_WHO_USER:
if (!who)
ret = -EINVAL;
}
- read_unlock_irq(&tasklist_lock);
+ read_unlock(&tasklist_lock);
return ret;
}