[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/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);
 }