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

["Benoît Canet" <benoit.canet@irqsave.net>]

The Tuesday 18 Feb 2014 à 17:37:08 (+0000), 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);
> 
> 
> > +            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);

These calls use the new syntax of bdrv_open based on the
"[PATCH v4 0/8] block: Integrate bdrv_file_open() into bdrv_open()" series
by Max Reitz.

Best regards

Benoît

> 
> 
> 
> > +            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