Re: [Qemu-devel] [5860] Cleanup {alloc|get}_cluster_offset() (Gleb Natapov)

[Alexander Graf]

Gleb,

do you have a Novell bugzilla account, so I can add you to the bug?  
Kevin apparently used some of his spare time (he's on vacation) to  
look at this as well.

Alex

On 11.12.2008, at 12:00, Gleb Natapov wrote:

> On Wed, Dec 10, 2008 at 08:38:19AM -0600, Anthony Liguori wrote:
> > Hi Gleb,
> >
> > Anthony Liguori wrote:
> > > Revision: 5860
> > >          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5860
> > > Author:   aliguori
> > > Date:     2008-12-02 20:11:27 +0000 (Tue, 02 Dec 2008)
> >
> > According to https://bugzilla.novell.com/show_bug.cgi?id=457957, this
> > changeset breaks compressed qcow2 on write and savevm.
> >
> > Can you please look into this?
> Alexander, can you try the patch below?
>
>
> diff --git a/block-qcow2.c b/block-qcow2.c
> index b3b5f8f..d8ac647 100644
> --- a/block-qcow2.c
> +++ b/block-qcow2.c
> @@ -620,6 +620,9 @@ static int count_contiguous_clusters(uint64_t  
> nb_clusters, int cluster_size,
>     int i;
>     uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask;
>
> +    if (!offset)
> +        return 0;
> +
>     for (i = 0; i < nb_clusters; i++)
>         if (offset + i * cluster_size != (be64_to_cpu(l2_table[i]) &  
> ~mask))
>             break;
> @@ -981,6 +984,12 @@ static uint64_t  
> alloc_cluster_offset(BlockDriverState *bs,
>     /* how many available clusters ? */
>
>     while (i < nb_clusters) {
> +        i += count_contiguous_clusters(nb_clusters - i, s- 
> >cluster_size,
> +                &l2_table[l2_index + i], 0);
> +
> +        if(be64_to_cpu(l2_table[l2_index + i]))
> +            break;
> +
>         i += count_contiguous_free_clusters(nb_clusters - i,
>                 &l2_table[l2_index + i]);
>
> @@ -989,12 +998,6 @@ static uint64_t  
> alloc_cluster_offset(BlockDriverState *bs,
>         if ((cluster_offset & QCOW_OFLAG_COPIED) ||
>                 (cluster_offset & QCOW_OFLAG_COMPRESSED))
>             break;
> -
> -        i += count_contiguous_clusters(nb_clusters - i, s- 
> >cluster_size,
> -                &l2_table[l2_index + i], 0);
> -
> -        if(be64_to_cpu(l2_table[l2_index + i]))
> -            break;
>     }
>     nb_clusters = i;
>
> --
>                         Gleb.