fs/adfs: add helper to get discrecord from map

Add a helper to get the disc record from the map, rather than open
coding this in adfs_fill_super().
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/adfs/adfs.h

 /* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/buffer_head.h>
 #include <linux/fs.h>
 #include <linux/adfs_fs.h>
 
@@ -18,8 +19,6 @@
 
 #include "dir_f.h"
 
-struct buffer_head;
-
 /*
  * adfs file system inode data in memory
  */
@@ -195,3 +194,10 @@ __adfs_block_map(struct super_block *sb, unsigned int object_id,
 
 	return adfs_map_lookup(sb, object_id >> 8, block);
 }
+
+/* Return the disc record from the map */
+static inline
+struct adfs_discrecord *adfs_map_discrecord(struct adfs_discmap *dm)
+{
+	return (void *)(dm[0].dm_bh->b_data + 4);
+}

fs/adfs/dir_f.c

@@ -9,7 +9,6 @@
  *
  *  E and F format directory handling
  */
-#include <linux/buffer_head.h>
 #include "adfs.h"
 #include "dir_f.h"
 

fs/adfs/dir_fplus.c

@@ -7,7 +7,6 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
-#include <linux/buffer_head.h>
 #include <linux/slab.h>
 #include "adfs.h"
 #include "dir_fplus.h"

fs/adfs/map.c

@@ -7,7 +7,6 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
-#include <linux/buffer_head.h>
 #include <asm/unaligned.h>
 #include "adfs.h"
 

fs/adfs/super.c

@@ -9,7 +9,6 @@
  */
 #include <linux/module.h>
 #include <linux/init.h>
-#include <linux/buffer_head.h>
 #include <linux/parser.h>
 #include <linux/mount.h>
 #include <linux/seq_file.h>
@@ -463,7 +462,7 @@ static int adfs_fill_super(struct super_block *sb, void *data, int silent)
 	 */
 	sb->s_op = &adfs_sops;
 
-	dr = (struct adfs_discrecord *)(asb->s_map[0].dm_bh->b_data + 4);
+	dr = adfs_map_discrecord(asb->s_map);
 
 	root_obj.parent_id = root_obj.file_id = le32_to_cpu(dr->root);
 	root_obj.name_len  = 0;