Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  block: Range check cpu in blk_cpu_to_group
  scatterlist: prevent invalid free when alloc fails
  writeback: Fix lost wake-up shutting down writeback thread
  writeback: do not lose wakeup events when forking bdi threads
  cciss: fix reporting of max queue depth since init
  block: switch s390 tape_block and mg_disk to elevator_change()
  block: add function call to switch the IO scheduler from a driver
  fs/bio-integrity.c: return -ENOMEM on kmalloc failure
  bio-integrity.c: remove dependency on __GFP_NOFAIL
  BLOCK: fix bio.bi_rw handling
  block: put dev->kobj in blk_register_queue fail path
  cciss: handle allocation failure
  cfq-iosched: Documentation help for new tunables
  cfq-iosched: blktrace print per slice sector stats
  cfq-iosched: Implement tunable group_idle
  cfq-iosched: Do group share accounting in IOPS when slice_idle=0
  cfq-iosched: Do not idle if slice_idle=0
  cciss: disable doorbell reset on reset_devices
  blkio: Fix return code for mkdir calls

1 files changed, 31 insertions, 13 deletions

diff --git a/block/elevator.c b/block/elevator.c
index ec585c9554d3..205b09a5bd9e 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -1009,18 +1009,19 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 {
 	struct elevator_queue *old_elevator, *e;
 	void *data;
+	int err;
 
 	/*
 	 * Allocate new elevator
 	 */
 	e = elevator_alloc(q, new_e);
 	if (!e)
-		return 0;
+		return -ENOMEM;
 
 	data = elevator_init_queue(q, e);
 	if (!data) {
 		kobject_put(&e->kobj);
-		return 0;
+		return -ENOMEM;
 	}
 
 	/*
@@ -1043,7 +1044,8 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 
 	__elv_unregister_queue(old_elevator);
 
-	if (elv_register_queue(q))
+	err = elv_register_queue(q);
+	if (err)
 		goto fail_register;
 
 	/*
@@ -1056,7 +1058,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 
 	blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);
 
-	return 1;
+	return 0;
 
 fail_register:
 	/*
@@ -1071,17 +1073,19 @@ fail_register:
 	queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
 	spin_unlock_irq(q->queue_lock);
 
-	return 0;
+	return err;
 }
 
-ssize_t elv_iosched_store(struct request_queue *q, const char *name,
-			  size_t count)
+/*
+ * Switch this queue to the given IO scheduler.
+ */
+int elevator_change(struct request_queue *q, const char *name)
 {
 	char elevator_name[ELV_NAME_MAX];
 	struct elevator_type *e;
 
 	if (!q->elevator)
-		return count;
+		return -ENXIO;
 
 	strlcpy(elevator_name, name, sizeof(elevator_name));
 	e = elevator_get(strstrip(elevator_name));
@@ -1092,13 +1096,27 @@ ssize_t elv_iosched_store(struct request_queue *q, const char *name,
 
 	if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
 		elevator_put(e);
-		return count;
+		return 0;
 	}
 
-	if (!elevator_switch(q, e))
-		printk(KERN_ERR "elevator: switch to %s failed\n",
-							elevator_name);
-	return count;
+	return elevator_switch(q, e);
+}
+EXPORT_SYMBOL(elevator_change);
+
+ssize_t elv_iosched_store(struct request_queue *q, const char *name,
+			  size_t count)
+{
+	int ret;
+
+	if (!q->elevator)
+		return count;
+
+	ret = elevator_change(q, name);
+	if (!ret)
+		return count;
+
+	printk(KERN_ERR "elevator: switch to %s failed\n", name);
+	return ret;
 }
 
 ssize_t elv_iosched_show(struct request_queue *q, char *name)