xfs: teach rmapbt to support interval queries

Now that the generic btree code supports querying all records within a
range of keys, use that functionality to allow us to ask for all the
extents mapped to a range of physical blocks.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/libxfs/xfs_rmap.c

@@ -183,3 +183,46 @@ xfs_rmap_alloc(
 	trace_xfs_rmap_map_error(mp, agno, error, _RET_IP_);
 	return error;
 }
+
+struct xfs_rmap_query_range_info {
+	xfs_rmap_query_range_fn	fn;
+	void				*priv;
+};
+
+/* Format btree record and pass to our callback. */
+STATIC int
+xfs_rmap_query_range_helper(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_rec	*rec,
+	void			*priv)
+{
+	struct xfs_rmap_query_range_info	*query = priv;
+	struct xfs_rmap_irec			irec;
+	int					error;
+
+	error = xfs_rmap_btrec_to_irec(rec, &irec);
+	if (error)
+		return error;
+	return query->fn(cur, &irec, query->priv);
+}
+
+/* Find all rmaps between two keys. */
+int
+xfs_rmap_query_range(
+	struct xfs_btree_cur		*cur,
+	struct xfs_rmap_irec		*low_rec,
+	struct xfs_rmap_irec		*high_rec,
+	xfs_rmap_query_range_fn	fn,
+	void				*priv)
+{
+	union xfs_btree_irec		low_brec;
+	union xfs_btree_irec		high_brec;
+	struct xfs_rmap_query_range_info	query;
+
+	low_brec.r = *low_rec;
+	high_brec.r = *high_rec;
+	query.priv = priv;
+	query.fn = fn;
+	return xfs_btree_query_range(cur, &low_brec, &high_brec,
+			xfs_rmap_query_range_helper, &query);
+}

fs/xfs/libxfs/xfs_rmap.h

@@ -151,4 +151,13 @@ int xfs_rmap_lookup_eq(struct xfs_btree_cur *cur, xfs_agblock_t bno,
 int xfs_rmap_get_rec(struct xfs_btree_cur *cur, struct xfs_rmap_irec *irec,
 		int *stat);
 
+typedef int (*xfs_rmap_query_range_fn)(
+	struct xfs_btree_cur	*cur,
+	struct xfs_rmap_irec	*rec,
+	void			*priv);
+
+int xfs_rmap_query_range(struct xfs_btree_cur *cur,
+		struct xfs_rmap_irec *low_rec, struct xfs_rmap_irec *high_rec,
+		xfs_rmap_query_range_fn fn, void *priv);
+
 #endif	/* __XFS_RMAP_H__ */