Re: [Qemu-devel] [PATCH v14 7/8] Implement new driver for block replication

[Eric Blake]

On 01/13/2016 02:18 AM, Changlong Xie wrote:
> From: Wen Congyang <address@hidden>
> 
> Signed-off-by: Wen Congyang <address@hidden>
> Signed-off-by: zhanghailiang <address@hidden>
> Signed-off-by: Gonglei <address@hidden>
> Signed-off-by: Changlong Xie <address@hidden>
> ---
>  block/Makefile.objs              |   1 +
>  block/replication-comm.c         |  66 +++++
>  block/replication.c              | 590 
> +++++++++++++++++++++++++++++++++++++++
>  include/block/replication-comm.h |  50 ++++
>  qapi/block-core.json             |  13 +
>  5 files changed, 720 insertions(+)
>  create mode 100644 block/replication-comm.c
>  create mode 100644 block/replication.c
>  create mode 100644 include/block/replication-comm.h
> 

Just a high-level overview, mainly on the user-visible interface and
things that caught my eye.

> +++ b/block/replication-comm.c
> @@ -0,0 +1,66 @@
> +/*
> + * Replication Block filter
> + *
> + * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
> + * Copyright (c) 2015 Intel Corporation
> + * Copyright (c) 2015 FUJITSU LIMITED

Do you want to claim 2016 in any of this?


> +
> +enum {
> +    BLOCK_REPLICATION_NONE,             /* block replication is not started 
> */
> +    BLOCK_REPLICATION_RUNNING,          /* block replication is running */
> +    BLOCK_REPLICATION_FAILOVER,         /* failover is running in background 
> */
> +    BLOCK_REPLICATION_FAILOVER_FAILED,  /* failover failed*/

Space before */

> +    BLOCK_REPLICATION_DONE,             /* block replication is done(after 
> failover) */
> +};

Should this be an enum type in a .json file?


> +
> +static int replication_open(BlockDriverState *bs, QDict *options,
> +                            int flags, Error **errp)
> +{

> +
> +fail:
> +    qemu_opts_del(opts);
> +    /* propagate error */
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +    }

It's safe to call error_propagate() unconditionally (you could drop the
'if (local_err)').


> +static coroutine_fn int replication_co_discard(BlockDriverState *bs,
> +                                               int64_t sector_num,
> +                                               int nb_sectors)
> +{
> +    BDRVReplicationState *s = bs->opaque;
> +    int ret;
> +
> +    ret = replication_get_io_status(s);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    if (ret == 1) {
> +        /* It is secondary qemu and failover are running*/

Space before */

> +static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp)
> +{
> +    Error *local_err = NULL;
> +    int ret;
> +
> +    if (!s->secondary_disk->job) {
> +        error_setg(errp, "Backup job is cancelled unexpectedly");

Maybe s/is/was/

> +static void replication_start(BlockReplicationState *brs, ReplicationMode 
> mode,
> +                              Error **errp)
> +{
> +    BlockDriverState *bs = brs->bs;
> +    BDRVReplicationState *s = brs->bs->opaque;
> +    int64_t active_length, hidden_length, disk_length;
> +    AioContext *aio_context;
> +    Error *local_err = NULL;
> +
> +    if (s->replication_state != BLOCK_REPLICATION_NONE) {
> +        error_setg(errp, "Block replication is running or done");
> +        return;
> +    }
> +
> +    if (s->mode != mode) {
> +        error_setg(errp, "The parameter mode's value is invalid, needs %d,"
> +                   " but receives %d", s->mode, mode);

s/receives/got/


> +static void replication_do_checkpoint(BlockReplicationState *brs, Error 
> **errp)
> +{
> +    BDRVReplicationState *s = brs->bs->opaque;
> +
> +    if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
> +        error_setg(errp, "Block replication is not running");
> +        return;
> +    }
> +
> +    if (s->error) {
> +        error_setg(errp, "I/O error occurs");

s/occurs/occurred/

> +++ b/qapi/block-core.json
> @@ -1975,6 +1975,19 @@
>              '*read-pattern': 'QuorumReadPattern' } }
>  
>  ##
> +# @ReplicationMode
> +#
> +# An enumeration of replication modes.
> +#
> +# @primary: Primary mode, the vm's state will be sent to secondary QEMU.
> +#
> +# @secondary: Secondary mode, receive the vm's state from primary QEMU.
> +#
> +# Since: 2.6
> +##
> +{ 'enum' : 'ReplicationMode', 'data' : [ 'primary', 'secondary' ] }
> +

Interface looks okay.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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