[PATCH] sysfs: (driver/block) if show/store is missing return -EIO

sysfs: fix drivers/block so if an attribute doesn't implement
       show or store method read/write will return -EIO
       instead of 0 or -EINVAL.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/block/as-iosched.c

@@ -2044,7 +2044,7 @@ as_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 	struct as_fs_entry *entry = to_as(attr);
 
 	if (!entry->show)
-		return 0;
+		return -EIO;
 
 	return entry->show(e->elevator_data, page);
 }
@@ -2057,7 +2057,7 @@ as_attr_store(struct kobject *kobj, struct attribute *attr,
 	struct as_fs_entry *entry = to_as(attr);
 
 	if (!entry->store)
-		return -EINVAL;
+		return -EIO;
 
 	return entry->store(e->elevator_data, page, length);
 }

drivers/block/cfq-iosched.c

@@ -1775,7 +1775,7 @@ cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 	struct cfq_fs_entry *entry = to_cfq(attr);
 
 	if (!entry->show)
-		return 0;
+		return -EIO;
 
 	return entry->show(e->elevator_data, page);
 }
@@ -1788,7 +1788,7 @@ cfq_attr_store(struct kobject *kobj, struct attribute *attr,
 	struct cfq_fs_entry *entry = to_cfq(attr);
 
 	if (!entry->store)
-		return -EINVAL;
+		return -EIO;
 
 	return entry->store(e->elevator_data, page, length);
 }

drivers/block/deadline-iosched.c

@@ -886,7 +886,7 @@ deadline_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 	struct deadline_fs_entry *entry = to_deadline(attr);
 
 	if (!entry->show)
-		return 0;
+		return -EIO;
 
 	return entry->show(e->elevator_data, page);
 }
@@ -899,7 +899,7 @@ deadline_attr_store(struct kobject *kobj, struct attribute *attr,
 	struct deadline_fs_entry *entry = to_deadline(attr);
 
 	if (!entry->store)
-		return -EINVAL;
+		return -EIO;
 
 	return entry->store(e->elevator_data, page, length);
 }

drivers/block/genhd.c

@@ -322,7 +322,7 @@ static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr,
 	struct gendisk *disk = to_disk(kobj);
 	struct disk_attribute *disk_attr =
 		container_of(attr,struct disk_attribute,attr);
-	ssize_t ret = 0;
+	ssize_t ret = -EIO;
 
 	if (disk_attr->show)
 		ret = disk_attr->show(disk,page);

drivers/block/ll_rw_blk.c

@@ -3574,7 +3574,7 @@ queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 
 	q = container_of(kobj, struct request_queue, kobj);
 	if (!entry->show)
-		return 0;
+		return -EIO;
 
 	return entry->show(q, page);
 }
@@ -3588,7 +3588,7 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr,
 
 	q = container_of(kobj, struct request_queue, kobj);
 	if (!entry->store)
-		return -EINVAL;
+		return -EIO;
 
 	return entry->store(q, page, length);
 }