Re: [Qemu-devel] [PATCH 11/20] qcow2: Handle failure for potentially large allocations

[Stefan Hajnoczi]

On Wed, May 21, 2014 at 06:28:09PM +0200, Kevin Wolf wrote:
> diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
> index 8ecbb5b..465ef24 100644
> --- a/block/qcow2-cache.c
> +++ b/block/qcow2-cache.c
> @@ -53,10 +53,20 @@ Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int 
> num_tables)
>      c->entries = g_malloc0(sizeof(*c->entries) * num_tables);
>  
>      for (i = 0; i < c->size; i++) {
> -        c->entries[i].table = qemu_blockalign(bs, s->cluster_size);
> +        c->entries[i].table = qemu_try_blockalign(bs, s->cluster_size);
> +        if (c->entries[i].table == NULL) {
> +            goto fail;
> +        }
>      }
>  
>      return c;
> +
> +fail:
> +    for (i = 0; i < c->size; i++) {
> +        g_free(c->entries[i].table);

qemu_blockalign() must be paired with qemu_vfree().

Come to think of it, in the patches where you converted malloc to
blockalign, please check that the buffer is vfreed.

> diff --git a/block/qcow2.c b/block/qcow2.c
> index a4b97e8..1efdd17 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -676,8 +676,13 @@ static int qcow2_open(BlockDriverState *bs, QDict 
> *options, int flags,
>  
>  
>      if (s->l1_size > 0) {
> -        s->l1_table = g_malloc0(
> +        s->l1_table = qemu_try_blockalign(bs->file,

Is blockalign used consistently for s->l1_table?  Or places in this
patch have l1_table = g_try_malloc0().  We need to be careful because of
g_free() vs qemu_vfree().