block: don't lose data from last incomplete sector

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>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/block.c b/block.c
index e176c6f3bcba6169ca57c0aba0ee055b41f1a8f2..ea4956d6c7e887754a2c11ff3339e3d12fa21040 100644 (file)
--- a/block.c
+++ b/block.c
@@ -2669,7 +2669,7 @@ 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,