Re: [Qemu-devel] [PATCH v23 09/12] Implement new driver for block replication

[Max Reitz]

On 26.07.2016 10:15, Changlong Xie wrote:
> From: Wen Congyang <address@hidden>
> 
> Signed-off-by: Wen Congyang <address@hidden>
> Signed-off-by: Changlong Xie <address@hidden>
> Signed-off-by: Wang WeiWei <address@hidden>
> Signed-off-by: zhanghailiang <address@hidden>
> Signed-off-by: Gonglei <address@hidden>
> ---
>  block/Makefile.objs |   1 +
>  block/replication.c | 658 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 659 insertions(+)
>  create mode 100644 block/replication.c

[...]

> diff --git a/block/replication.c b/block/replication.c
> new file mode 100644
> index 0000000..ec35348
> --- /dev/null
> +++ b/block/replication.c
> @@ -0,0 +1,658 @@

[...]

> +static void replication_start(ReplicationState *rs, ReplicationMode mode,
> +                              Error **errp)
> +{

[...]

> +        /* start backup job now */
> +        error_setg(&s->blocker,
> +                   "Block device is in use by internal backup job");
> +
> +        top_bs = bdrv_lookup_bs(s->top_id, s->top_id, errp);

I think you should pass NULL instead of errp...

> +        if (!top_bs || !check_top_bs(top_bs, bs)) {
> +            error_setg(errp, "No top_bs or it is invalid");

...or if you don't, then you should not call this function if top_bs is
NULL. Otherwise you'll probably get a failed assertion in error_setv()
because *errp is not NULL.

> +            reopen_backing_file(s, false, NULL);
> +            aio_context_release(aio_context);
> +            return;
> +        }
> +        bdrv_op_block_all(top_bs, s->blocker);
> +        bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);

Shouldn't you make sure that top_bs is a root node? The first patch in
Kevin's "block: Accept node-name in all node level QMP commands" series
introduces the bdrv_is_root_node() function for that purpose.

Maybe that check should be put into check_top_bs().

Max

> +
> +        backup_start("replication-backup", s->secondary_disk->bs,
> +                     s->hidden_disk->bs, 0, MIRROR_SYNC_MODE_NONE, NULL,
> +                     BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
> +                     backup_job_completed, s, NULL, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            backup_job_cleanup(s);
> +            aio_context_release(aio_context);
> +            return;
> +        }
> +        break;

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