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Date: Thu, 06 Nov 2008 18:32:48 +0100
From: Kevin Wolf <kwolf@suse.de>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH 1/4] qcow2: Clean-up
	update_cluster_refcount().
References: <20081106165212.380421945@bull.net>
	<1225990557.6576.11.camel@frecb07144>
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To: qemu-devel@nongnu.org
Cc: Laurent Vivier <Laurent.Vivier@bull.net>

Laurent Vivier schrieb:
> pi=C3=A8ce jointe document texte brut
> (0001-Clean-up-update_cluster_refcount.patch)
> Move some parts to alloc_refcount_block() and block cache
>  checking to load_refcount_block().
>=20
> Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
> ---
>  block-qcow2.c |   71 +++++++++++++++++++++++++++++++++++--------------=
---------
>  1 file changed, 43 insertions(+), 28 deletions(-)
>=20
> Index: qemu/block-qcow2.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- qemu.orig/block-qcow2.c	2008-11-06 16:34:46.000000000 +0100
> +++ qemu/block-qcow2.c	2008-11-06 16:40:27.000000000 +0100
> @@ -2169,6 +2169,10 @@ static int load_refcount_block(BlockDriv
>  {
>      BDRVQcowState *s =3D bs->opaque;
>      int ret;
> +
> +    if (refcount_block_offset =3D=3D s->refcount_block_cache_offset)
> +        return 0;
> +
>      ret =3D bdrv_pread(s->hd, refcount_block_offset, s->refcount_block=
_cache,
>                       s->cluster_size);
>      if (ret !=3D s->cluster_size)
> @@ -2189,11 +2193,8 @@ static int get_refcount(BlockDriverState
>      refcount_block_offset =3D s->refcount_table[refcount_table_index];
>      if (!refcount_block_offset)
>          return 0;
> -    if (refcount_block_offset !=3D s->refcount_block_cache_offset) {
> -        /* better than nothing: return allocated if read error */
> -        if (load_refcount_block(bs, refcount_block_offset) < 0)
> -            return 1;
> -    }
> +    if (load_refcount_block(bs, refcount_block_offset) < 0)
> +        return 1;

Please retain the comment saying that 1 is not the correct value but we
default to allocated for safety if the block could not be read. I don't
think this is obvious.

Otherwise the patch looks fine to me.

Kevin