I used the clang-tidy qemu-round check to generate the fix:
https://github.com/elmarco/clang-tools-extra

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 block/vhdx-log.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/vhdx-log.c b/block/vhdx-log.c
index 3f4c2aa095..6125ea4c6d 100644
--- a/block/vhdx-log.c
+++ b/block/vhdx-log.c
@@ -884,7 +884,7 @@ static int vhdx_log_write(BlockDriverState *bs, BDRVVHDXState *s,
     }
 
     sector_offset = offset % VHDX_LOG_SECTOR_SIZE;
-    file_offset = (offset / VHDX_LOG_SECTOR_SIZE) * VHDX_LOG_SECTOR_SIZE;
+    file_offset = QEMU_ALIGN_DOWN(offset, VHDX_LOG_SECTOR_SIZE);
 
     aligned_length = length;
 
-- 
2.13.1.395.gf7b71de06