[Qemu-devel] [PATCH 1/2] block: don't lose data from last incomplete sector

[Fam Zheng <famz@redhat.com>]

To read the last sector that is not aligned to sector boundary, current
code for growable backends, since commit 893a8f6 "block: Produce zeros
when protocols reading beyond end of file", drops the data and directly
returns zeroes. That is incorrect.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block.c b/block.c
index a325efc..9b28ef9 100644
--- a/block.c
+++ b/block.c
@@ -2613,7 +2613,7 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
             goto out;
         }
 
-        total_sectors = len >> BDRV_SECTOR_BITS;
+        total_sectors = (len + BDRV_SECTOR_SIZE - 1) >> BDRV_SECTOR_BITS;
         max_nb_sectors = MAX(0, total_sectors - sector_num);
         if (max_nb_sectors > 0) {
             ret = drv->bdrv_co_readv(bs, sector_num,
-- 
1.8.3.1