fscrypt: Constify struct inode pointer

Some filesystems, such as UBIFS, maintain a const pointer for struct
inode.

Signed-off-by: David Gstir <david@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 9a28133..faeaf0b 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -220,7 +220,7 @@ static int digest_decode(const char *src, int len, char *dst)
 	return cp - dst;
 }
 
-u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen)
+u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen)
 {
 	int padding = 32;
 	struct fscrypt_info *ci = inode->i_crypt_info;
@@ -238,7 +238,7 @@ EXPORT_SYMBOL(fscrypt_fname_encrypted_size);
  * Allocates an output buffer that is sufficient for the crypto operation
  * specified by the context and the direction.
  */
-int fscrypt_fname_alloc_buffer(struct inode *inode,
+int fscrypt_fname_alloc_buffer(const struct inode *inode,
 				u32 ilen, struct fscrypt_str *crypto_str)
 {
 	unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen);