[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>
diff --git a/drivers/block/as-iosched.c b/drivers/block/as-iosched.c
index a9575bb..638db06 100644
--- a/drivers/block/as-iosched.c
+++ b/drivers/block/as-iosched.c
@@ -2044,7 +2044,7 @@
 	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 @@
 	struct as_fs_entry *entry = to_as(attr);
 
 	if (!entry->store)
-		return -EINVAL;
+		return -EIO;
 
 	return entry->store(e->elevator_data, page, length);
 }
diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c
index 2210bac..3ac47dd 100644
--- a/drivers/block/cfq-iosched.c
+++ b/drivers/block/cfq-iosched.c
@@ -1775,7 +1775,7 @@
 	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 @@
 	struct cfq_fs_entry *entry = to_cfq(attr);
 
 	if (!entry->store)
-		return -EINVAL;
+		return -EIO;
 
 	return entry->store(e->elevator_data, page, length);
 }
diff --git a/drivers/block/deadline-iosched.c b/drivers/block/deadline-iosched.c
index d63d34c..7f79f3d 100644
--- a/drivers/block/deadline-iosched.c
+++ b/drivers/block/deadline-iosched.c
@@ -886,7 +886,7 @@
 	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 @@
 	struct deadline_fs_entry *entry = to_deadline(attr);
 
 	if (!entry->store)
-		return -EINVAL;
+		return -EIO;
 
 	return entry->store(e->elevator_data, page, length);
 }
diff --git a/drivers/block/genhd.c b/drivers/block/genhd.c
index 8bbe01d..53f7d84 100644
--- a/drivers/block/genhd.c
+++ b/drivers/block/genhd.c
@@ -322,7 +322,7 @@
 	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);
diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index f20eba2..81fe3a0 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -3574,7 +3574,7 @@
 
 	q = container_of(kobj, struct request_queue, kobj);
 	if (!entry->show)
-		return 0;
+		return -EIO;
 
 	return entry->show(q, page);
 }
@@ -3588,7 +3588,7 @@
 
 	q = container_of(kobj, struct request_queue, kobj);
 	if (!entry->store)
-		return -EINVAL;
+		return -EIO;
 
 	return entry->store(q, page, length);
 }