btrfs: introduce item_nr token variant helpers

The last remaining place where we have the pattern of

	item = btrfs_item_nr(slot)
	<do something with the item>

are the token helpers.  Handle this by introducing token helpers that
will do the btrfs_item_nr() work inside of the helper itself, and then
convert all users of the btrfs_item token helpers to the new _nr()
variants.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e0cb78f..53fc204 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2009,6 +2009,38 @@ static inline void btrfs_set_item_offset_nr(struct extent_buffer *eb, int nr,
 	btrfs_set_item_offset(eb, btrfs_item_nr(nr), val);
 }
 
+static inline u32 btrfs_token_item_offset_nr(struct btrfs_map_token *token,
+					     int slot)
+{
+	struct btrfs_item *item = btrfs_item_nr(slot);
+
+	return btrfs_token_item_offset(token, item);
+}
+
+static inline u32 btrfs_token_item_size_nr(struct btrfs_map_token *token,
+					   int slot)
+{
+	struct btrfs_item *item = btrfs_item_nr(slot);
+
+	return btrfs_token_item_size(token, item);
+}
+
+static inline void btrfs_set_token_item_offset_nr(struct btrfs_map_token *token,
+						  int slot, u32 val)
+{
+	struct btrfs_item *item = btrfs_item_nr(slot);
+
+	btrfs_set_token_item_offset(token, item, val);
+}
+
+static inline void btrfs_set_token_item_size_nr(struct btrfs_map_token *token,
+						int slot, u32 val)
+{
+	struct btrfs_item *item = btrfs_item_nr(slot);
+
+	btrfs_set_token_item_size(token, item, val);
+}
+
 static inline void btrfs_item_key(const struct extent_buffer *eb,
 			   struct btrfs_disk_key *disk_key, int nr)
 {