cleancache: constify cleancache_ops structure

---
 drivers/xen/tmem.c         | 2 +-
 include/linux/cleancache.h | 2 +-
 mm/cleancache.c            | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)
 
diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c
index 945fc43..4ac2ca8 100644
--- a/drivers/xen/tmem.c
+++ b/drivers/xen/tmem.c
@@ -242,7 +242,7 @@ static int tmem_cleancache_init_shared_fs(char *uuid, size_t pagesize)
 	return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
 }
 
-static struct cleancache_ops tmem_cleancache_ops = {
+static const struct cleancache_ops tmem_cleancache_ops = {
 	.put_page = tmem_cleancache_put_page,
 	.get_page = tmem_cleancache_get_page,
 	.invalidate_page = tmem_cleancache_flush_page,
diff --git a/include/linux/cleancache.h b/include/linux/cleancache.h
index bda5ec0b4..cb3e142 100644
--- a/include/linux/cleancache.h
+++ b/include/linux/cleancache.h
@@ -37,7 +37,7 @@ struct cleancache_ops {
 	void (*invalidate_fs)(int);
 };
 
-extern int cleancache_register_ops(struct cleancache_ops *ops);
+extern int cleancache_register_ops(const struct cleancache_ops *ops);
 extern void __cleancache_init_fs(struct super_block *);
 extern void __cleancache_init_shared_fs(struct super_block *);
 extern int  __cleancache_get_page(struct page *);
diff --git a/mm/cleancache.c b/mm/cleancache.c
index 8fc5081..ba5d8f3 100644
--- a/mm/cleancache.c
+++ b/mm/cleancache.c
@@ -22,7 +22,7 @@
  * cleancache_ops is set by cleancache_register_ops to contain the pointers
  * to the cleancache "backend" implementation functions.
  */
-static struct cleancache_ops *cleancache_ops __read_mostly;
+static const struct cleancache_ops *cleancache_ops __read_mostly;
 
 /*
  * Counters available via /sys/kernel/debug/cleancache (if debugfs is
@@ -49,7 +49,7 @@ static void cleancache_register_ops_sb(struct super_block *sb, void *unused)
 /*
  * Register operations for cleancache. Returns 0 on success.
  */
-int cleancache_register_ops(struct cleancache_ops *ops)
+int cleancache_register_ops(const struct cleancache_ops *ops)
 {
 	if (cmpxchg(&cleancache_ops, NULL, ops))
 		return -EBUSY;