From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Fabian Ebner <f.ebner@proxmox.com>
Date: Wed, 22 Jun 2022 10:45:13 +0200
Subject: [PATCH] block: alloc-track: avoid premature break

While the bdrv_co_preadv() calls are expected to return 0 on success,
qemu_iovec_memset() will return the number of bytes set (will be
local_bytes, because the slice with that size was just initialized).

Don't break out of the loop after the branch with qemu_iovec_memset(),
because there might still be work to do. Additionally, ret is an int,
which on 64-bit platforms is too small to hold the size_t returned by
qemu_iovec_memset().

The branch seems to be difficult to reach in practice, because the
whole point of alloc-track is to be used with a backing device.

Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
---
 block/alloc-track.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/alloc-track.c b/block/alloc-track.c
index 43d40d11af..95c9c67cd8 100644
--- a/block/alloc-track.c
+++ b/block/alloc-track.c
@@ -174,7 +174,8 @@ static int coroutine_fn track_co_preadv(BlockDriverState *bs,
             ret = bdrv_co_preadv(bs->backing, local_offset, local_bytes,
                                  &local_qiov, flags);
         } else {
-            ret = qemu_iovec_memset(&local_qiov, cur_offset, 0, local_bytes);
+            qemu_iovec_memset(&local_qiov, cur_offset, 0, local_bytes);
+            ret = 0;
         }
 
         if (ret != 0) {
