Re: [Qemu-block] [PATCH v5 18/27] mirror: Disable image locking on target backing chain

[Max Reitz]

On 17.05.2016 09:35, Fam Zheng wrote:
> In sync=none the backing image of s->target is s->common.bs, which could
> be exclusively locked, the image locking wouldn't work here.

Why is the backing image s->common.bs when the bdrv_open() call
explicitly specifies BDRV_O_NO_BACKING?

Max

> Later we can update completion code to lock it after the replaced node
> has dropped its lock.
> 
> Signed-off-by: Fam Zheng <address@hidden>
> ---
>  blockdev.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/blockdev.c b/blockdev.c
> index 250e3d2..3de54f0 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3626,6 +3626,12 @@ void qmp_drive_mirror(const char *device, const char 
> *target,
>       * file.
>       */
>      target_bs = NULL;
> +    if (sync == MIRROR_SYNC_MODE_NONE) {
> +        flags |= BDRV_O_NO_LOCK;
> +    }
> +    /* TODO: in mirror complete, after target_bs is switched to and the
> +     * original BDS's lock is dropped, we should enable the lock on 
> target_bs.
> +     * */
>      ret = bdrv_open(&target_bs, target, NULL, options,
>                      flags | BDRV_O_NO_BACKING, &local_err);
>      if (ret < 0) {
>

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