xfs: Replace macro XFS_DQUOT_TREE with a function

In preparation for combined pquota/gquota support, for the sake
of readability, change the macro to an inline function.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_qm.h b/fs/xfs/xfs_qm.h
index 5d16a6e..96568c2 100644
--- a/fs/xfs/xfs_qm.h
+++ b/fs/xfs/xfs_qm.h
@@ -69,12 +69,22 @@
 	struct shrinker  qi_shrinker;
 } xfs_quotainfo_t;
 
-#define XFS_DQUOT_TREE(qi, type) \
-	((type & XFS_DQ_USER) ? \
-	 &((qi)->qi_uquota_tree) : \
-	 &((qi)->qi_gquota_tree))
-
-
+static inline struct radix_tree_root *
+xfs_dquot_tree(
+	struct xfs_quotainfo	*qi,
+	int			type)
+{
+	switch (type) {
+	case XFS_DQ_USER:
+		return &qi->qi_uquota_tree;
+	case XFS_DQ_GROUP:
+	case XFS_DQ_PROJ:
+		return &qi->qi_gquota_tree;
+	default:
+		ASSERT(0);
+	}
+	return NULL;
+}
 extern int	xfs_qm_calc_dquots_per_chunk(struct xfs_mount *mp,
 					     unsigned int nbblks);
 extern void	xfs_trans_mod_dquot(xfs_trans_t *, xfs_dquot_t *, uint, long);