1 files changed, 5 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index ae22d01ecf54..16fb6bbe6e28 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -578,6 +578,11 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio)
         map_tree = &root->fs_info->mapping_tree;
         map_length = length;
         ret = btrfs_map_block(map_tree, logical, &physical, &map_length, &dev);
+        if (map_length < length) {
+                printk("mapping failed logical %Lu bio len %Lu physical %Lu "
+                       "len %Lu\n", logical, length, physical, map_length);
+                BUG();
+        }
         BUG_ON(map_length < length);
         bio->bi_sector = physical >> 9;
         bio->bi_bdev = dev->bdev;