fscrypt: move fscrypt_ctx declaration to fscrypt_supp.h

Filesystems only ever access 'struct fscrypt_ctx' through fscrypt
functions.  But when a filesystem is built without encryption support,
these functions are all stubbed out, so the declaration of fscrypt_ctx
is unneeded.  Therefore, move it from fscrypt.h to fscrypt_supp.h.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

include/linux/fscrypt.h

@@ -24,23 +24,9 @@
 
 #define FS_CRYPTO_BLOCK_SIZE		16
 
+struct fscrypt_ctx;
 struct fscrypt_info;
 
-struct fscrypt_ctx {
-	union {
-		struct {
-			struct page *bounce_page;	/* Ciphertext page */
-			struct page *control_page;	/* Original page  */
-		} w;
-		struct {
-			struct bio *bio;
-			struct work_struct work;
-		} r;
-		struct list_head free_list;	/* Free list */
-	};
-	u8 flags;				/* Flags */
-};
-
 /**
  * For encrypted symlinks, the ciphertext length is stored at the beginning
  * of the string in little-endian format.

include/linux/fscrypt_supp.h

@@ -11,6 +11,21 @@
 #ifndef _LINUX_FSCRYPT_SUPP_H
 #define _LINUX_FSCRYPT_SUPP_H
 
+struct fscrypt_ctx {
+	union {
+		struct {
+			struct page *bounce_page;	/* Ciphertext page */
+			struct page *control_page;	/* Original page  */
+		} w;
+		struct {
+			struct bio *bio;
+			struct work_struct work;
+		} r;
+		struct list_head free_list;	/* Free list */
+	};
+	u8 flags;				/* Flags */
+};
+
 static inline bool fscrypt_has_encryption_key(const struct inode *inode)
 {
 	return (inode->i_crypt_info != NULL);