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

[Max Reitz <mreitz@redhat.com>]

On 18.02.2014 18:37, Leandro Dorileo wrote:
> 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);

This series is meant to be applied on my bdrv_open()/bdrv_file_open() 
series which added a new "reference" string parameter to bdrv_open() 
(after the filename). Giving NULL for that parameter is correct here.

>> +            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);

Here, the string is given as that new reference parameter. Therefore, 
this is correct as well (when applied on top of my series).

Max

>> +            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
>>
>>