1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e6417a573d44..0e658c1d8211 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -883,6 +883,9 @@ again:
         spin_lock(&em_tree->lock);
         em = lookup_extent_mapping(em_tree, logical, *length);
         spin_unlock(&em_tree->lock);
+        if (!em) {
+                printk("unable to find logical %Lu\n", logical);
+        }
         BUG_ON(!em);
 
         BUG_ON(em->start > logical || em->start + em->len < logical);