Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-serial

[pandora-kernel.git] / fs / ioprio.c

diff --git a/fs/ioprio.c b/fs/ioprio.c
index 4bf1c63..6dc6721 100644 (file)
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -1,7 +1,7 @@
 /*
  * 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
@@ -22,23 +22,33 @@
 #include <linux/kernel.h>
 #include <linux/ioprio.h>
 #include <linux/blkdev.h>
+#include <linux/capability.h>
 #include <linux/syscalls.h>
+#include <linux/security.h>
 
 static int set_task_ioprio(struct task_struct *task, int ioprio)
 {
+       int err;
        struct io_context *ioc;
 
        if (task->uid != current->euid &&
            task->uid != current->uid && !capable(CAP_SYS_NICE))
                return -EPERM;
 
+       err = security_task_setioprio(task, ioprio);
+       if (err)
+               return err;
+
        task_lock(task);
 
        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;
@@ -71,7 +81,12 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
        }
 
        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)
@@ -104,9 +119,9 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
                                        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;
@@ -114,17 +129,53 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
                        ret = -EINVAL;
        }
 
-       read_unlock_irq(&tasklist_lock);
+       read_unlock(&tasklist_lock);
        return ret;
 }
 
+static int get_task_ioprio(struct task_struct *p)
+{
+       int ret;
+
+       ret = security_task_getioprio(p);
+       if (ret)
+               goto out;
+       ret = p->ioprio;
+out:
+       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 (!ioprio_valid(aprio))
+               return bprio;
+       if (!ioprio_valid(bprio))
+               return aprio;
+
+       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;
        int ret = -ESRCH;
+       int tmpio;
 
-       read_lock_irq(&tasklist_lock);
+       read_lock(&tasklist_lock);
        switch (which) {
                case IOPRIO_WHO_PROCESS:
                        if (!who)
@@ -132,16 +183,19 @@ asmlinkage long sys_ioprio_get(int which, int who)
                        else
                                p = find_task_by_pid(who);
                        if (p)
-                               ret = p->ioprio;
+                               ret = get_task_ioprio(p);
                        break;
                case IOPRIO_WHO_PGRP:
                        if (!who)
                                who = process_group(current);
                        do_each_task_pid(who, PIDTYPE_PGID, p) {
+                               tmpio = get_task_ioprio(p);
+                               if (tmpio < 0)
+                                       continue;
                                if (ret == -ESRCH)
-                                       ret = p->ioprio;
+                                       ret = tmpio;
                                else
-                                       ret = ioprio_best(ret, p->ioprio);
+                                       ret = ioprio_best(ret, tmpio);
                        } while_each_task_pid(who, PIDTYPE_PGID, p);
                        break;
                case IOPRIO_WHO_USER:
@@ -156,10 +210,13 @@ asmlinkage long sys_ioprio_get(int which, int who)
                        do_each_thread(g, p) {
                                if (p->uid != user->uid)
                                        continue;
+                               tmpio = get_task_ioprio(p);
+                               if (tmpio < 0)
+                                       continue;
                                if (ret == -ESRCH)
-                                       ret = p->ioprio;
+                                       ret = tmpio;
                                else
-                                       ret = ioprio_best(ret, p->ioprio);
+                                       ret = ioprio_best(ret, tmpio);
                        } while_each_thread(g, p);
 
                        if (who)
@@ -169,7 +226,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
                        ret = -EINVAL;
        }
 
-       read_unlock_irq(&tasklist_lock);
+       read_unlock(&tasklist_lock);
        return ret;
 }