xfs: factor out a xfs_btree_owner helper

Split out a helper to calculate the owner for a given btree instead of
duplicating the logic in two places.  While we're at it, make the
bc_ag/bc_ino switch logic depend on the correct geometry flag.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: break this up into two patches for the owner check]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/xfs/libxfs/xfs_btree.c

@@ -1222,6 +1222,15 @@ xfs_btree_init_buf(
 	bp->b_ops = ops->buf_ops;
 }
 
+static inline __u64
+xfs_btree_owner(
+	struct xfs_btree_cur    *cur)
+{
+	if (cur->bc_ops->geom_flags & XFS_BTGEO_ROOT_IN_INODE)
+		return cur->bc_ino.ip->i_ino;
+	return cur->bc_ag.pag->pag_agno;
+}
+
 void
 xfs_btree_init_block_cur(
 	struct xfs_btree_cur	*cur,
@@ -1229,20 +1238,8 @@ xfs_btree_init_block_cur(
 	int			level,
 	int			numrecs)
 {
-	__u64			owner;
-
-	/*
-	 * we can pull the owner from the cursor right now as the different
-	 * owners align directly with the pointer size of the btree. This may
-	 * change in future, but is safe for current users of the generic btree
-	 * code.
-	 */
-	if (cur->bc_ops->geom_flags & XFS_BTGEO_LONG_PTRS)
-		owner = cur->bc_ino.ip->i_ino;
-	else
-		owner = cur->bc_ag.pag->pag_agno;
-
-	xfs_btree_init_buf(cur->bc_mp, bp, cur->bc_ops, level, numrecs, owner);
+	xfs_btree_init_buf(cur->bc_mp, bp, cur->bc_ops, level, numrecs,
+			xfs_btree_owner(cur));
 }
 
 /*