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From: Alberto Garcia <berto@igalia.com>
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Date: Fri, 15 May 2015 11:04:13 +0200
Message-ID: <w51egmiqkj6.fsf@maestria.local.igalia.com>
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Subject: Re: [Qemu-devel] [PATCH 04/11] block: Support streaming to an
	intermediate layer
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To: Fam Zheng <famz@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org

On Fri 15 May 2015 04:33:19 AM CEST, Fam Zheng wrote:

>> +    /* Make sure that the image is opened in read-write mode */
>> +    orig_bs_flags = bdrv_get_flags(bs);
>> +    if (!(orig_bs_flags & BDRV_O_RDWR)) {
>> +        if (bdrv_reopen(bs, orig_bs_flags | BDRV_O_RDWR, errp) != 0) {
>
> I don't think all bdrv_reopen implementation will guarantee to set errp
> on error :(. For example:
>
>     static int qcow2_reopen_prepare(BDRVReopenState *state,
>                                     BlockReopenQueue *queue, Error **errp)
>     {

bdrv_reopen_prepare() already sets a generic error if the implementation
(qcow2_reopen_prepare() in this case) doesn't provide one:

    ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err);
    if (ret) {
        if (local_err != NULL) {
            error_propagate(errp, local_err);
        } else {
            error_setg(errp, "failed while preparing to reopen image '%s'",
                       reopen_state->bs->filename);
        }
        goto error;
    }

Berto