[PATCH] null_blk: Constify struct configfs_item_operations and configfs_group_operations

[Christophe JAILLET]

'struct configfs_item_operations' and 'configfs_group_operations' are not
modified in this driver.

Constifying these structures moves some data to a read-only section, so
increases overall security, especially when the structure holds some
function pointers.

On a x86_64, with allmodconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
 100263	  37808	   2752	 140823	  22617	drivers/block/null_blk/main.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
 100423	  37648	   2752	 140823	  22617	drivers/block/null_blk/main.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
Compile tested only.

This change is possible since commits f2f36500a63b and f7f78098690d.
---
 drivers/block/null_blk/main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index c7c0fb79a6bf..29a371f48b57 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -642,7 +642,7 @@ static void nullb_device_release(struct config_item *item)
 	null_free_dev(dev);
 }
 
-static struct configfs_item_operations nullb_device_ops = {
+static const struct configfs_item_operations nullb_device_ops = {
 	.release	= nullb_device_release,
 };
 
@@ -739,7 +739,7 @@ static struct configfs_attribute *nullb_group_attrs[] = {
 	NULL,
 };
 
-static struct configfs_group_operations nullb_group_ops = {
+static const struct configfs_group_operations nullb_group_ops = {
 	.make_group	= nullb_group_make_group,
 	.drop_item	= nullb_group_drop_item,
 };
-- 
2.52.0