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Date: Tue, 26 Nov 2013 17:18:07 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v5 5/7] block: Parse "backing" option to
 reference existing BDS
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To: Fam Zheng <famz@redhat.com>
Cc: kwolf@redhat.com, hbrock@redhat.com, qemu-devel@nongnu.org, rjones@redhat.com, imain@redhat.com, stefanha@redhat.com

Il 26/11/2013 05:05, Fam Zheng ha scritto:
> +    if (backing_bs && *backing_bs != '\0') {
> +        bs->backing_hd = bdrv_find(backing_bs);
> +        if (!bs->backing_hd) {
> +            error_setg(errp, "Backing device not found: %s", backing_bs);
> +            return -ENOENT;
> +        }
> +        bdrv_ref(bs->backing_hd);
> +        assert(!bs->backing_blocker);
> +        error_setg(&bs->backing_blocker,
> +                   "device is used as backing hd of '%s'",
> +                   bs->device_name);
> +        bdrv_op_block_all(bs->backing_hd, bs->backing_blocker);

Why should this blocker only apply to the "named backing file" case, and
not to all backing files?

Paolo

> +        pstrcpy(bs->backing_file, sizeof(bs->backing_file),
> +                bs->backing_hd->filename);
> +        pstrcpy(bs->backing_format, sizeof(bs->backing_format),
> +                bs->backing_hd->drv->format_name);
> +    }