ceph: document locking for ceph_set_dentry_offset

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

diff --git a/fs/ioprio.c b/fs/ioprio.c
index bb5210af77c2871aea4c93ec6304aa27fda7f87c..7da2a06508e5448c59aebcee03518d78f2b0599b 100644 (file)
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -19,6 +19,7 @@
  * See also Documentation/block/ioprio.txt
  *
  */
+#include <linux/gfp.h>
 #include <linux/kernel.h>
 #include <linux/ioprio.h>
 #include <linux/blkdev.h>
@@ -27,14 +28,20 @@
 #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->cred->uid != current_euid() &&
-           task->cred->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)
@@ -64,8 +71,9 @@ static int set_task_ioprio(struct task_struct *task, int ioprio)
        task_unlock(task);
        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);
@@ -95,12 +103,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
        }
 
        ret = -ESRCH;
-       /*
-        * 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);
+       rcu_read_lock();
        switch (which) {
                case IOPRIO_WHO_PROCESS:
                        if (!who)
@@ -123,7 +126,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
                        break;
                case IOPRIO_WHO_USER:
                        if (!who)
-                               user = current->cred->user;
+                               user = current_user();
                        else
                                user = find_user(who);
 
@@ -131,7 +134,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
                                break;
 
                        do_each_thread(g, p) {
-                               if (p->cred->uid != who)
+                               if (__task_cred(p)->uid != who)
                                        continue;
                                ret = set_task_ioprio(p, ioprio);
                                if (ret)
@@ -145,7 +148,7 @@ free_uid:
                        ret = -EINVAL;
        }
 
-       read_unlock(&tasklist_lock);
+       rcu_read_unlock();
        return ret;
 }
 
@@ -181,7 +184,7 @@ 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;
@@ -189,7 +192,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
        int ret = -ESRCH;
        int tmpio;
 
-       read_lock(&tasklist_lock);
+       rcu_read_lock();
        switch (which) {
                case IOPRIO_WHO_PROCESS:
                        if (!who)
@@ -216,7 +219,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
                        break;
                case IOPRIO_WHO_USER:
                        if (!who)
-                               user = current->cred->user;
+                               user = current_user();
                        else
                                user = find_user(who);
 
@@ -224,7 +227,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
                                break;
 
                        do_each_thread(g, p) {
-                               if (p->cred->uid != user->uid)
+                               if (__task_cred(p)->uid != user->uid)
                                        continue;
                                tmpio = get_task_ioprio(p);
                                if (tmpio < 0)
@@ -242,7 +245,6 @@ asmlinkage long sys_ioprio_get(int which, int who)
                        ret = -EINVAL;
        }
 
-       read_unlock(&tasklist_lock);
+       rcu_read_unlock();
        return ret;
 }
-