Fill in missing queue limitations when table is complete instead of
enforcing the "default" limits on every dm device.
Problem noticed by Mike Christie.

[Christophe Saout]
--- diff/drivers/md/dm-table.c	2004-02-18 09:16:19.000000000 +0000
+++ source/drivers/md/dm-table.c	2004-02-18 09:16:56.000000000 +0000
@@ -624,14 +624,20 @@
 	return 0;
 }
 
-static void set_default_limits(struct io_restrictions *rs)
+static void check_for_valid_limits(struct io_restrictions *rs)
 {
-	rs->max_sectors = MAX_SECTORS;
-	rs->max_phys_segments = MAX_PHYS_SEGMENTS;
-	rs->max_hw_segments = MAX_HW_SEGMENTS;
-	rs->hardsect_size = 1 << SECTOR_SHIFT;
-	rs->max_segment_size = MAX_SEGMENT_SIZE;
-	rs->seg_boundary_mask = -1;
+	if (!rs->max_sectors)
+		rs->max_sectors = MAX_SECTORS;
+	if (!rs->max_phys_segments)
+		rs->max_phys_segments = MAX_PHYS_SEGMENTS;
+	if (!rs->max_hw_segments)
+		rs->max_hw_segments = MAX_HW_SEGMENTS;
+	if (!rs->hardsect_size)
+		rs->hardsect_size = 1 << SECTOR_SHIFT;
+	if (!rs->max_segment_size)
+		rs->max_segment_size = MAX_SEGMENT_SIZE;
+	if (!rs->seg_boundary_mask)
+		rs->seg_boundary_mask = -1;
 }
 
 int dm_table_add_target(struct dm_table *t, const char *type,
@@ -646,7 +652,6 @@
 
 	tgt = t->targets + t->num_targets;
 	memset(tgt, 0, sizeof(*tgt));
-	set_default_limits(&tgt->limits);
 
 	if (!len) {
 		tgt->error = "zero-length target";
@@ -731,6 +736,8 @@
 	int r = 0;
 	unsigned int leaf_nodes;
 
+	check_for_valid_limits(&t->limits);
+
 	/* how many indexes will the btree have ? */
 	leaf_nodes = dm_div_up(t->num_targets, KEYS_PER_NODE);
 	t->depth = 1 + int_log(leaf_nodes, CHILDREN_PER_NODE);