const: mark struct vm_struct_operations

* mark struct vm_area_struct::vm_ops as const
* mark vm_ops in AGP code

But leave TTM code alone, something is fishy there with global vm_ops
being used.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 86d6b4d..f5fdd39 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -59,7 +59,7 @@
 static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl);
 static int nfs_setlease(struct file *file, long arg, struct file_lock **fl);
 
-static struct vm_operations_struct nfs_file_vm_ops;
+static const struct vm_operations_struct nfs_file_vm_ops;
 
 const struct file_operations nfs_file_operations = {
 	.llseek		= nfs_file_llseek,
@@ -572,7 +572,7 @@
 	return VM_FAULT_SIGBUS;
 }
 
-static struct vm_operations_struct nfs_file_vm_ops = {
+static const struct vm_operations_struct nfs_file_vm_ops = {
 	.fault = filemap_fault,
 	.page_mkwrite = nfs_vm_page_mkwrite,
 };