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Date: Sat, 18 Jun 2011 17:46:28 +0100
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From: Stefan Hajnoczi <stefanha@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 07/12] VMDK: vmdk_flush for extents
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To: Fam Zheng <famcool@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org, Christoph Hellwig <hch@lst.de>

On Sat, Jun 4, 2011 at 1:42 AM, Fam Zheng <famcool@gmail.com> wrote:
> Vmdk flush in extent array style.
>
>
> Signed-off-by: Fam Zheng <famcool@gmail.com>
> ---
> =A0block/vmdk.c | =A0 =A09 ++++++++-
> =A01 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/block/vmdk.c b/block/vmdk.c
> index f1233cf..1d74b62 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1094,7 +1094,14 @@ static void vmdk_close(BlockDriverState *bs)
>
> =A0static int vmdk_flush(BlockDriverState *bs)
> =A0{
> - =A0 =A0return bdrv_flush(bs->file);
> + =A0 =A0int i, ret;
> + =A0 =A0BDRVVmdkState *s =3D bs->opaque;
> +
> + =A0 =A0ret =3D bdrv_flush(bs->file);
> + =A0 =A0for (i =3D 0; i < s->num_extents; i++) {
> + =A0 =A0 =A0 =A0ret |=3D bdrv_flush(s->extents[i].file);

This could produce an invalid return code (e.g. ORing together two
different errnos).

I think the best you can do is:
for (...) {
    ret =3D bdrv_flush(s->extents[i].file);
    if (ret < 0) {
        err =3D ret;
    }
}
return err;

This loses multiple errnos but it doesn't have the potential to corrupt the=
m.

Stefan