[Qemu-devel] [PATCH] qcow2: don't ignore failed update_refcount

[Jim Meyering <jim@meyering.net>]

update_refcount is marked as a function for which we must use its result,

    static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,

and rightly so, since doing otherwise would amount to ignoring write failure.
However, there are two cases in which the return value is currently ignored.
This fixes them:

>From 107940556a2d0ef1de1d59a5da0c6c3086246817 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering@redhat.com>
Date: Mon, 8 Feb 2010 11:50:59 +0100
Subject: [PATCH] qcow2: don't ignore failed update_refcount

* block/qcow2-refcount.c (grow_refcount_table): When update_refcount
fails, return its negative return code to our caller.
(alloc_refcount_block): Likewise.
---
 block/qcow2-refcount.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 2fdc26b..b9f5093 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -181,7 +181,9 @@ static int grow_refcount_table(BlockDriverState *bs, int min_size)
     s->refcount_table_size = new_table_size;
     s->refcount_table_offset = table_offset;

-    update_refcount(bs, table_offset, new_table_size2, 1);
+    ret = update_refcount(bs, table_offset, new_table_size2, 1);
+    if (ret < 0)
+	goto fail;
     qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t));
     return 0;
  fail:
@@ -231,7 +233,9 @@ static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index)

         refcount_block_offset = offset;
         s->refcount_block_cache_offset = offset;
-        update_refcount(bs, offset, s->cluster_size, 1);
+        ret = update_refcount(bs, offset, s->cluster_size, 1);
+        if (ret < 0)
+            return ret;
         cache_refcount_updates = cache;
     } else {
         if (refcount_block_offset != s->refcount_block_cache_offset) {
--
1.7.0.rc2.156.g2ac04