Fix variable pblk len, cleanup, rearrange

This is tested with the performance profile and works.

Lots of cleanup and rearranging also.

libcbd/format.c

@@ -112,6 +112,12 @@ cbd_format(const char* dev,
             ((psize / pblk_size) <= 0xffff ? 2 :
                     ((psize / pblk_size) <= 0xffffffff ? 4 : 6));
     header.params.pbat_shift = pbatshift;
+    if (pbat_len(&header.params) * pblk_size > PAGE_SIZE) {
+        error("Physical block allocation table too large\n");
+    }
+    if (lba_len(&header.params) > pblk_size) {
+        error("lba element size too large\n");
+    }
     /* XXX: Initial estimate */
     header.params.lblk_per_zone = zone_data_len(&header.params) * (lsize / lblk_size) / (psize / pblk_size);
     printf("  initial estimate for lblk_per_zone: %lu\n", (unsigned long)header.params.lblk_per_zone);