Re: [Qemu-devel] [PATCH V18 11/12] quorum: Add quorum_open() and quorum_close().

[Leandro Dorileo <l@dorileo.org>]

On Tue, Feb 18, 2014 at 01:11:26PM +0100, Beno??t Canet wrote:
> From: Beno??t Canet <benoit@irqsave.net>
> 
> Example of command line:
> 
> -drive if=virtio,driver=quorum,\
> children.0.file.filename=1.raw,\
> children.0.node-name=1.raw,\
> children.0.driver=raw,\
> children.1.file.filename=2.raw,\
> children.1.node-name=2.raw,\
> children.1.driver=raw,\
> children.2.file.filename=3.raw,\
> children.2.node-name=3.raw,\
> children.2.driver=raw,\
> vote-threshold=2
> 
> blkverify=on with vote-threshold=2 and two files can be passed to
> emulate blkverify.
> 
> Signed-off-by: Benoit Canet <benoit@irqsave.net>
> ---
>  block/quorum.c   | 161 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  monitor.c        |   3 ++
>  qapi-schema.json |  21 +++++++-
>  3 files changed, 184 insertions(+), 1 deletion(-)
> 
> diff --git a/block/quorum.c b/block/quorum.c
> index 40832c0..18721ba 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -20,6 +20,9 @@
>  
>  #define HASH_LENGTH 32
>  
> +#define QUORUM_OPT_VOTE_THRESHOLD "vote-threshold"
> +#define QUORUM_OPT_BLKVERIFY      "blkverify"
> +
>  /* This union holds a vote hash value */
>  typedef union QuorumVoteValue {
>      char h[HASH_LENGTH];       /* SHA-256 hash */
> @@ -672,12 +675,170 @@ static bool quorum_recurse_is_first_non_filter(BlockDriverState *bs,
>      return false;
>  }
>  
> +static int quorum_valid_threshold(int threshold, int num_children, Error **errp)
> +{
> +
> +    if (threshold < 1) {
> +        error_set(errp, QERR_INVALID_PARAMETER_VALUE,
> +                  "vote-threshold", "value >= 1");
> +        return -ERANGE;
> +    }
> +
> +    if (threshold > num_children) {
> +        error_setg(errp, "threshold may not exceed children count");
> +        return -ERANGE;
> +    }
> +
> +    return 0;
> +}
> +
> +static QemuOptsList quorum_runtime_opts = {
> +    .name = "quorum",
> +    .head = QTAILQ_HEAD_INITIALIZER(quorum_runtime_opts.head),
> +    .desc = {
> +        {
> +            .name = QUORUM_OPT_VOTE_THRESHOLD,
> +            .type = QEMU_OPT_NUMBER,
> +            .help = "The number of vote needed for reaching quorum",
> +        },
> +        {
> +            .name = QUORUM_OPT_BLKVERIFY,
> +            .type = QEMU_OPT_BOOL,
> +            .help = "Trigger block verify mode if set",
> +        },
> +        { /* end of list */ }
> +    },
> +};
> +
> +static int quorum_open(BlockDriverState *bs, QDict *options, int flags,
> +                       Error **errp)
> +{
> +    BDRVQuorumState *s = bs->opaque;
> +    Error *local_err = NULL;
> +    QemuOpts *opts;
> +    bool *opened;
> +    QDict *sub = NULL;
> +    QList *list = NULL;
> +    const QListEntry *lentry;
> +    const QDictEntry *dentry;
> +    int i;
> +    int ret = 0;
> +
> +    qdict_flatten(options);
> +    qdict_extract_subqdict(options, &sub, "children.");
> +    qdict_array_split(sub, &list);
> +
> +    /* count how many different children are present and validate
> +     * qdict_size(sub) address the open by reference case
> +     */
> +    s->num_children = !qlist_size(list) ? qdict_size(sub) : qlist_size(list);
> +    if (s->num_children < 2) {
> +        error_setg(&local_err,
> +                   "Number of provided children must be greater than 1");
> +        ret = -EINVAL;
> +        goto exit;
> +    }
> +
> +    opts = qemu_opts_create(&quorum_runtime_opts, NULL, 0, &error_abort);
> +    qemu_opts_absorb_qdict(opts, options, &local_err);
> +    if (error_is_set(&local_err)) {
> +        ret = -EINVAL;
> +        goto exit;
> +    }
> +
> +    s->threshold = qemu_opt_get_number(opts, QUORUM_OPT_VOTE_THRESHOLD, 0);
> +
> +    /* and validate it against s->num_children */
> +    ret = quorum_valid_threshold(s->threshold, s->num_children, &local_err);
> +    if (ret < 0) {
> +        goto exit;
> +    }
> +
> +    /* is the driver in blkverify mode */
> +    if (qemu_opt_get_bool(opts, QUORUM_OPT_BLKVERIFY, false) &&
> +        s->num_children == 2 && s->threshold == 2) {
> +        s->is_blkverify = true;
> +    } else if (qemu_opt_get_bool(opts, QUORUM_OPT_BLKVERIFY, false)) {
> +        fprintf(stderr, "blkverify mode is set by setting blkverify=on "
> +                "and using two files with vote_threshold=2\n");
> +    }
> +
> +    /* allocate the children BlockDriverState array */
> +    s->bs = g_new0(BlockDriverState *, s->num_children);
> +    opened = g_new0(bool, s->num_children);
> +
> +    /* Open by file name or options dict (command line or QMP) */
> +    if (s->num_children == qlist_size(list)) {
> +        for (i = 0, lentry = qlist_first(list); lentry;
> +            lentry = qlist_next(lentry), i++) {
> +            QDict *d = qobject_to_qdict(lentry->value);
> +            QINCREF(d);
> +            ret = bdrv_open(&s->bs[i], NULL, NULL, d, flags, NULL, &local_err);


Shouldn't this bdrv_open call be?

ret = bdrv_open(s->bs[i], NULL, d, flags, NULL, &local_err);


> +            if (ret < 0) {
> +                goto close_exit;
> +            }
> +            opened[i] = true;
> +        }
> +    /* Open by QMP references */
> +    } else {
> +        for (i = 0, dentry = qdict_first(sub); dentry;
> +             dentry = qdict_next(sub, dentry), i++) {
> +            QString *string = qobject_to_qstring(dentry->value);
> +            ret = bdrv_open(&s->bs[i], NULL, qstring_get_str(string), NULL,
> +                            flags, NULL, &local_err);


This other bdrv_open() call seems to be not right as well, I think it should be:

            ret = bdrv_open(s->bs[i], qstring_get_str(string), NULL,
                            flags, NULL, &local_err);



> +            if (ret < 0) {
> +                goto close_exit;
> +            }
> +            opened[i] = true;
> +        }
> +    }
> +
> +    g_free(opened);
> +    goto exit;
> +
> +close_exit:
> +    /* cleanup on error */
> +    for (i = 0; i < s->num_children; i++) {
> +        if (!opened[i]) {
> +            continue;
> +        }
> +        bdrv_unref(s->bs[i]);
> +    }
> +    g_free(s->bs);
> +    g_free(opened);
> +exit:
> +    /* propagate error */
> +    if (error_is_set(&local_err)) {
> +        error_propagate(errp, local_err);
> +    }
> +    QDECREF(list);
> +    QDECREF(sub);
> +    return ret;
> +}
> +
> +static void quorum_close(BlockDriverState *bs)
> +{
> +    BDRVQuorumState *s = bs->opaque;
> +    int i;
> +
> +    for (i = 0; i < s->num_children; i++) {
> +        bdrv_unref(s->bs[i]);
> +    }
> +
> +    g_free(s->bs);
> +}
> +
>  static BlockDriver bdrv_quorum = {
>      .format_name        = "quorum",
>      .protocol_name      = "quorum",
>  
>      .instance_size      = sizeof(BDRVQuorumState),
>  
> +    .bdrv_file_open     = quorum_open,
> +    .bdrv_close         = quorum_close,
> +
> +    .authorizations     = { true, true },
> +
>      .bdrv_co_flush_to_disk = quorum_co_flush,
>  
>      .bdrv_getlength     = quorum_getlength,
> diff --git a/monitor.c b/monitor.c
> index 81ffa0f..ed5bb98 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -639,6 +639,9 @@ static void monitor_protocol_event_init(void)
>      monitor_protocol_event_throttle(QEVENT_RTC_CHANGE, 1000);
>      monitor_protocol_event_throttle(QEVENT_BALLOON_CHANGE, 1000);
>      monitor_protocol_event_throttle(QEVENT_WATCHDOG, 1000);
> +    /* limit the rate of quorum events to avoid hammering the management */
> +    monitor_protocol_event_throttle(QEVENT_QUORUM_REPORT_BAD, 1000);
> +    monitor_protocol_event_throttle(QEVENT_QUORUM_FAILURE, 1000);
>  }
>  
>  /**
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 7cfb5e5..990d0c5 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -4352,6 +4352,24 @@
>              'raw': 'BlockdevRef' } }
>  
>  ##
> +# @BlockdevOptionsQuorum
> +#
> +# Driver specific block device options for Quorum
> +#
> +# @blkverify:      #optional true if the driver must print content mismatch
> +#
> +# @children:       the children block device to use
> +#
> +# @vote_threshold: the vote limit under which a read will fail
> +#
> +# Since: 2.0
> +##
> +{ 'type': 'BlockdevOptionsQuorum',
> +  'data': { '*blkverify': 'bool',
> +            'children': [ 'BlockdevRef' ],
> +            'vote-threshold': 'int' } }
> +
> +##
>  # @BlockdevOptions
>  #
>  # Options for creating a block device.
> @@ -4390,7 +4408,8 @@
>        'vdi':        'BlockdevOptionsGenericFormat',
>        'vhdx':       'BlockdevOptionsGenericFormat',
>        'vmdk':       'BlockdevOptionsGenericCOWFormat',
> -      'vpc':        'BlockdevOptionsGenericFormat'
> +      'vpc':        'BlockdevOptionsGenericFormat',
> +      'quorum':     'BlockdevOptionsQuorum'
>    } }
>  
>  ##
> -- 
> 1.8.3.2
> 
> 

-- 
Leandro Dorileo