diff -aur linux-4.2/fs/btrfs/extent_map.c linux-4.2.new/fs/btrfs/extent_map.c
--- linux-4.2/fs/btrfs/extent_map.c	2015-11-25 15:50:35.308419023 -0500
+++ linux-4.2.new/fs/btrfs/extent_map.c	2015-11-25 15:50:24.691870310 -0500
@@ -235,6 +235,7 @@
 			em->start = merge->start;
 			em->orig_start = merge->orig_start;
 			em->len += merge->len;
+			printk(KERN_ERR "PAX try_merge_map: em->block_len: %llu, merge->block_len: %llu\n", em->block_len, merge->block_len);
 			em->block_len += merge->block_len;
 			em->block_start = merge->block_start;
 			em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;