block: Reduce bdrv_aligned_preadv() rounding

Now that bdrv_is_allocated accepts non-aligned inputs, we can
remove the TODO added in commit d6a644bb.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/io.c

@@ -1124,18 +1124,14 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child,
     }
 
     if (flags & BDRV_REQ_COPY_ON_READ) {
-        /* TODO: Simplify further once bdrv_is_allocated no longer
-         * requires sector alignment */
-        int64_t start = QEMU_ALIGN_DOWN(offset, BDRV_SECTOR_SIZE);
-        int64_t end = QEMU_ALIGN_UP(offset + bytes, BDRV_SECTOR_SIZE);
         int64_t pnum;
 
-        ret = bdrv_is_allocated(bs, start, end - start, &pnum);
+        ret = bdrv_is_allocated(bs, offset, bytes, &pnum);
         if (ret < 0) {
             goto out;
         }
 
-        if (!ret || pnum != end - start) {
+        if (!ret || pnum != bytes) {
             ret = bdrv_co_do_copy_on_readv(child, offset, bytes, qiov);
             goto out;
         }