X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=fs%2Fioprio.c;h=10d2c211d18b28414aa8b0f26dcfe489fa0ddfe9;hb=ecd27b92fbb41f779d857632a69bd45dbaf0f915;hp=93aa5715f224cd5163e070473dc04e6d76409667;hpb=ba290ab7dace8b3339c0cc86c221d48eed21e956;p=linux-2.6

diff --git a/fs/ioprio.c b/fs/ioprio.c
index 93aa5715f2..10d2c211d1 100644
--- 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
@@ -44,8 +44,11 @@ static int set_task_ioprio(struct task_struct *task, int ioprio)
 	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;
@@ -57,6 +60,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
 	int data = IOPRIO_PRIO_DATA(ioprio);
 	struct task_struct *p, *g;
 	struct user_struct *user;
+	struct pid *pgrp;
 	int ret;
 
 	switch (class) {
@@ -78,7 +82,12 @@ 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)
@@ -90,12 +99,14 @@ asmlinkage long sys_ioprio_set(int which, int who, int 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_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)
@@ -111,9 +122,9 @@ 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;
@@ -121,7 +132,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
 			ret = -EINVAL;
 	}
 
-	read_unlock_irq(&tasklist_lock);
+	read_unlock(&tasklist_lock);
 	return ret;
 }
 
@@ -137,14 +148,33 @@ 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 (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)
@@ -156,8 +186,10 @@ asmlinkage long sys_ioprio_get(int which, int 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;
@@ -165,7 +197,7 @@ 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_task(pgrp, PIDTYPE_PGID, p);
 			break;
 		case IOPRIO_WHO_USER:
 			if (!who)
@@ -195,7 +227,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
 			ret = -EINVAL;
 	}
 
-	read_unlock_irq(&tasklist_lock);
+	read_unlock(&tasklist_lock);
 	return ret;
 }