Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfs
[linux-2.6.git] / fs / ioprio.c
index 78b1dea..c7c0b28 100644 (file)
@@ -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
 #include <linux/capability.h>
 #include <linux/syscalls.h>
 #include <linux/security.h>
+#include <linux/pid_namespace.h>
 
-static int set_task_ioprio(struct task_struct *task, int ioprio)
+int set_task_ioprio(struct task_struct *task, int ioprio)
 {
        int err;
        struct io_context *ioc;
+       const struct cred *cred = current_cred(), *tcred;
 
-       if (task->uid != current->euid &&
-           task->uid != current->uid && !capable(CAP_SYS_NICE))
+       rcu_read_lock();
+       tcred = __task_cred(task);
+       if (tcred->uid != cred->euid &&
+           tcred->uid != cred->uid && !capable(CAP_SYS_NICE)) {
+               rcu_read_unlock();
                return -EPERM;
+       }
+       rcu_read_unlock();
 
        err = security_task_setioprio(task, ioprio);
        if (err)
                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 && ioc->set_ioprio)
-               ioc->set_ioprio(ioc, ioprio);
+       if (!err) {
+               ioc->ioprio = ioprio;
+               ioc->ioprio_changed = 1;
+       }
 
        task_unlock(task);
-       return 0;
+       return err;
 }
+EXPORT_SYMBOL_GPL(set_task_ioprio);
 
-asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
+SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
 {
        int class = IOPRIO_PRIO_CLASS(ioprio);
        int data = IOPRIO_PRIO_DATA(ioprio);
        struct task_struct *p, *g;
        struct user_struct *user;
+       struct pid *pgrp;
        int ret;
 
        switch (class) {
@@ -73,36 +92,45 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
 
                        break;
                case IOPRIO_CLASS_IDLE:
-                       if (!capable(CAP_SYS_ADMIN))
-                               return -EPERM;
+                       break;
+               case IOPRIO_CLASS_NONE:
+                       if (data)
+                               return -EINVAL;
                        break;
                default:
                        return -EINVAL;
        }
 
        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)
                                p = current;
                        else
-                               p = find_task_by_pid(who);
+                               p = find_task_by_vpid(who);
                        if (p)
                                ret = set_task_ioprio(p, ioprio);
                        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_vpid(who);
+                       do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
                                ret = set_task_ioprio(p, ioprio);
                                if (ret)
                                        break;
-                       } while_each_task_pid(who, PIDTYPE_PGID, p);
+                       } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
                        break;
                case IOPRIO_WHO_USER:
                        if (!who)
-                               user = current->user;
+                               user = current_user();
                        else
                                user = find_user(who);
 
@@ -110,7 +138,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
                                break;
 
                        do_each_thread(g, p) {
-                               if (p->uid != who)
+                               if (__task_cred(p)->uid != who)
                                        continue;
                                ret = set_task_ioprio(p, ioprio);
                                if (ret)
@@ -124,7 +152,7 @@ free_uid:
                        ret = -EINVAL;
        }
 
-       read_unlock_irq(&tasklist_lock);
+       read_unlock(&tasklist_lock);
        return ret;
 }
 
@@ -135,7 +163,9 @@ 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;
 }
@@ -145,11 +175,6 @@ 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)
@@ -163,27 +188,30 @@ int ioprio_best(unsigned short aprio, unsigned short bprio)
                return aprio;
 }
 
-asmlinkage long sys_ioprio_get(int which, int who)
+SYSCALL_DEFINE2(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)
                                p = current;
                        else
-                               p = find_task_by_pid(who);
+                               p = find_task_by_vpid(who);
                        if (p)
                                ret = get_task_ioprio(p);
                        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_vpid(who);
+                       do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
                                tmpio = get_task_ioprio(p);
                                if (tmpio < 0)
                                        continue;
@@ -191,11 +219,11 @@ asmlinkage long sys_ioprio_get(int which, int who)
                                        ret = tmpio;
                                else
                                        ret = ioprio_best(ret, tmpio);
-                       } while_each_task_pid(who, PIDTYPE_PGID, p);
+                       } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
                        break;
                case IOPRIO_WHO_USER:
                        if (!who)
-                               user = current->user;
+                               user = current_user();
                        else
                                user = find_user(who);
 
@@ -203,7 +231,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
                                break;
 
                        do_each_thread(g, p) {
-                               if (p->uid != user->uid)
+                               if (__task_cred(p)->uid != user->uid)
                                        continue;
                                tmpio = get_task_ioprio(p);
                                if (tmpio < 0)
@@ -221,7 +249,6 @@ asmlinkage long sys_ioprio_get(int which, int who)
                        ret = -EINVAL;
        }
 
-       read_unlock_irq(&tasklist_lock);
+       read_unlock(&tasklist_lock);
        return ret;
 }
-