[Qemu-block] [PATCH 1/5] block: Tighter assertions on bdrv_aligned_preadv()

[Eric Blake]

Make sure everything is aligned to the passed-in alignment,
not just sectors.  Also makes sure that the computation of
max_nb_sectors later in the function will not divide by
zero, by guaranteeing align is at least a sector.

Signed-off-by: Eric Blake <address@hidden>
---
 block/io.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/io.c b/block/io.c
index dff4384..81618b9 100644
--- a/block/io.c
+++ b/block/io.c
@@ -947,8 +947,9 @@ static int coroutine_fn 
bdrv_aligned_preadv(BlockDriverState *bs,
     int64_t sector_num = offset >> BDRV_SECTOR_BITS;
     unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;

-    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
-    assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
+    assert(align / BDRV_SECTOR_SIZE);
+    assert((offset & (align - 1)) == 0);
+    assert((bytes & (align - 1)) == 0);
     assert(!qiov || bytes == qiov->size);
     assert((bs->open_flags & BDRV_O_NO_IO) == 0);

-- 
2.5.5