dm thin metadata: Fix trivial math error in on-disk format documentation
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index ca03b38..4e44274 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -28,7 +28,7 @@
*
* - A hierarchical btree, with 2 levels which effectively maps (thin
* dev id, virtual block) -> block_time. Block time is a 64-bit
- * field holding the time in the low 24 bits, and block in the top 48
+ * field holding the time in the low 24 bits, and block in the top 40
* bits.
*
* BTrees consist solely of btree_nodes, that fill a block. Some are