On Thu, Aug 03, 2017 at 10:07:41AM +0200, Kevin Wolf wrote:
>Am 31.07.2017 um 11:54 hat Manos Pitsidianakis geschrieben:
>> +/* Extract ThrottleConfig options. Assumes cfg is initialized and will be
>> + * checked for validity.
>> + */
>> +static int throttle_extract_options(QemuOpts *opts, ThrottleConfig *cfg,
>> +                                     Error **errp)
>> +{
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL)) {
>> +        cfg->buckets[THROTTLE_BPS_TOTAL].avg =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL,
>> +                                0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ)) {
>> +        cfg->buckets[THROTTLE_BPS_READ].avg  =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ,
>> +                                0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE)) {
>> +        cfg->buckets[THROTTLE_BPS_WRITE].avg =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE,
>> +                                0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL)) {
>> +        cfg->buckets[THROTTLE_OPS_TOTAL].avg =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL,
>> +                                0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ)) {
>> +        cfg->buckets[THROTTLE_OPS_READ].avg =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ,
>> +                                0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE)) {
>> +        cfg->buckets[THROTTLE_OPS_WRITE].avg =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE,
>> +                                0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL_MAX)) {
>> +        cfg->buckets[THROTTLE_BPS_TOTAL].max =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_TOTAL_MAX, 0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ_MAX)) {
>> +        cfg->buckets[THROTTLE_BPS_READ].max  =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_READ_MAX, 0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE_MAX)) {
>> +        cfg->buckets[THROTTLE_BPS_WRITE].max =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_WRITE_MAX, 0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL_MAX)) {
>> +        cfg->buckets[THROTTLE_OPS_TOTAL].max =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_TOTAL_MAX, 0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ_MAX)) {
>> +        cfg->buckets[THROTTLE_OPS_READ].max =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_READ_MAX, 0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE_MAX)) {
>> +        cfg->buckets[THROTTLE_OPS_WRITE].max =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_WRITE_MAX, 0);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL_MAX_LENGTH)) {
>> +        if (qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_TOTAL_MAX_LENGTH, 1) > UINT_MAX) {
>> +            error_setg(errp, "%s value must be in the range [0, %u]",
>> +                       THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL_MAX_LENGTH,
>> +                       UINT_MAX);
>> +            return -1;
>> +        }
>> +        cfg->buckets[THROTTLE_BPS_TOTAL].burst_length =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_TOTAL_MAX_LENGTH, 1);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ_MAX_LENGTH)) {
>> +        if (qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_READ_MAX_LENGTH, 1) > UINT_MAX) {
>> +            error_setg(errp, "%s must be in the range [0, %u]",
>> +                       THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ_MAX_LENGTH,
>> +                       UINT_MAX);
>> +            return -1;
>> +        }
>> +        cfg->buckets[THROTTLE_BPS_READ].burst_length  =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_READ_MAX_LENGTH, 1);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE_MAX_LENGTH)) {
>> +        if (qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_WRITE_MAX_LENGTH, 1) > UINT_MAX) {
>> +            error_setg(errp, "%s must be in the range [0, %u]",
>> +                       THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE_MAX_LENGTH,
>> +                       UINT_MAX);
>> +            return -1;
>> +        }
>> +        cfg->buckets[THROTTLE_BPS_WRITE].burst_length =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_BPS_WRITE_MAX_LENGTH, 1);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL_MAX_LENGTH)) {
>> +        if (qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_TOTAL_MAX_LENGTH, 1) > UINT_MAX) {
>> +            error_setg(errp, "%s must be in the range [0, %u]",
>> +                       THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL_MAX_LENGTH,
>> +                       UINT_MAX);
>> +            return -1;
>> +        }
>> +        cfg->buckets[THROTTLE_OPS_TOTAL].burst_length =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_TOTAL_MAX_LENGTH, 1);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ_MAX_LENGTH)) {
>> +        if (qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_READ_MAX_LENGTH, 1) > UINT_MAX) {
>> +            error_setg(errp, "%s must be in the range [0, %u]",
>> +                       THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ_MAX_LENGTH,
>> +                       UINT_MAX);
>> +            return -1;
>> +        }
>> +        cfg->buckets[THROTTLE_OPS_READ].burst_length =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_READ_MAX_LENGTH, 1);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE_MAX_LENGTH)) {
>> +        if (qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_WRITE_MAX_LENGTH, 1) > UINT_MAX) {
>> +            error_setg(errp, "%s must be in the range [0, %u]",
>> +                       THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE_MAX_LENGTH,
>> +                       UINT_MAX);
>> +            return -1;
>> +        }
>> +        cfg->buckets[THROTTLE_OPS_WRITE].burst_length =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX
>> +                                QEMU_OPT_IOPS_WRITE_MAX_LENGTH, 1);
>> +    }
>> +    if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_SIZE)) {
>> +        cfg->op_size =
>> +            qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_SIZE,
>> +                                0);
>> +    }
>> +    return 0;
>> +}
>
>This function is very repetitive, but each block is long enough that
>you have to look closely to review whether the right constants are used
>everywhere.
>
>Maybe this could become a bit more readable with a macro or two?

How about this?


#   #define IF_OPT_SET(rvalue,opt_name) \
#       if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX opt_name)) { \
#           rvalue = qemu_opt_get_number(opts, THROTTLE_OPT_PREFIX opt_name, 0); } 

#       IF_OPT_SET(cfg->buckets[THROTTLE_BPS_TOTAL].avg, QEMU_OPT_BPS_TOTAL);
#       IF_OPT_SET(cfg->buckets[THROTTLE_BPS_READ].avg, QEMU_OPT_BPS_READ);
#       IF_OPT_SET(cfg->buckets[THROTTLE_BPS_WRITE].avg, QEMU_OPT_BPS_WRITE);
#       IF_OPT_SET(cfg->buckets[THROTTLE_OPS_TOTAL].avg, QEMU_OPT_IOPS_TOTAL);
#       IF_OPT_SET(cfg->buckets[THROTTLE_OPS_READ].avg, QEMU_OPT_IOPS_READ);
#       IF_OPT_SET(cfg->buckets[THROTTLE_OPS_WRITE].avg, QEMU_OPT_IOPS_WRITE);
#       IF_OPT_SET(cfg->buckets[THROTTLE_BPS_TOTAL].max, QEMU_OPT_BPS_TOTAL_MAX);
#       IF_OPT_SET(cfg->buckets[THROTTLE_BPS_READ].max , QEMU_OPT_BPS_READ_MAX);
#       IF_OPT_SET(cfg->buckets[THROTTLE_BPS_WRITE].max, QEMU_OPT_BPS_WRITE_MAX);
#       IF_OPT_SET(cfg->buckets[THROTTLE_OPS_TOTAL].max, QEMU_OPT_IOPS_TOTAL_MAX);
#       IF_OPT_SET(cfg->buckets[THROTTLE_OPS_READ].max, QEMU_OPT_IOPS_READ_MAX);
#       IF_OPT_SET(cfg->buckets[THROTTLE_OPS_WRITE].max, QEMU_OPT_IOPS_WRITE_MAX);
#       IF_OPT_SET(cfg->op_size, QEMU_OPT_IOPS_SIZE);

#   #define IF_OPT_UINT_SET(rvalue,opt_name) \
#       if (qemu_opt_get(opts, THROTTLE_OPT_PREFIX opt_name)) { \
#           if (qemu_opt_get_number(opts,  \
#                       THROTTLE_OPT_PREFIX opt_name, 1) > UINT_MAX) { \
#               error_setg(errp, "%s value must be in the range [0, %u]", \
#                          THROTTLE_OPT_PREFIX opt_name, UINT_MAX); \
#               return -1; \
#           } \
#           rvalue = qemu_opt_get_number(opts, opt_name, 1); \
#       }

#       IF_OPT_UINT_SET(cfg->buckets[THROTTLE_BPS_TOTAL].burst_length,
#                       QEMU_OPT_BPS_TOTAL_MAX_LENGTH);
#       IF_OPT_UINT_SET(cfg->buckets[THROTTLE_BPS_READ].burst_length,
#                       QEMU_OPT_BPS_READ_MAX_LENGTH);
#       IF_OPT_UINT_SET(cfg->buckets[THROTTLE_BPS_WRITE].burst_length,
#                       QEMU_OPT_BPS_WRITE_MAX_LENGTH);
#       IF_OPT_UINT_SET(cfg->buckets[THROTTLE_OPS_TOTAL].burst_length,
#                       QEMU_OPT_IOPS_TOTAL_MAX_LENGTH);
#       IF_OPT_UINT_SET(cfg->buckets[THROTTLE_OPS_READ].burst_length,
#                       QEMU_OPT_IOPS_READ_MAX_LENGTH);
#       IF_OPT_UINT_SET(cfg->buckets[THROTTLE_OPS_WRITE].burst_length,
#                       QEMU_OPT_IOPS_WRITE_MAX_LENGTH);



>> +static int throttle_configure_tgm(BlockDriverState *bs,
>> +                                  ThrottleGroupMember *tgm,
>> +                                  QDict *options, Error **errp)
>> +{
>> +    int ret;
>> +    ThrottleConfig cfg;
>> +    const char *group_name = NULL;
>> +    Error *local_err = NULL;
>> +    QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return -EINVAL;
>> +    }
>
>As Stefan said, qemu_opts_create() can't fail if you pass NULL for id,
>so you can just use &error_abort.
>
>> +
>> +    qemu_opts_absorb_qdict(opts, options, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        goto err;
>> +    }
>> +
>> +    /* If no name is specified, an anonymous group will be created */
>> +    group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);
>> +
>> +    /* Register membership to group with name group_name */
>> +    throttle_group_register_tgm(tgm, group_name, bdrv_get_aio_context(bs));
>
>The documentation of throttle_group_register_tgm() suggests that you
>have to pass a string here, but group_name can be NULL if the option
>wasn't given. Probably just means that the comment for that function
>needs to be updated.
>
>> +    /* Copy previous configuration */
>> +    throttle_group_get_config(tgm, &cfg);
>> +
>> +    /* Change limits if user has specified them */
>> +    if (throttle_extract_options(opts, &cfg, errp) ||
>> +        !throttle_is_valid(&cfg, errp)) {
>> +        throttle_group_unregister_tgm(tgm);
>> +        goto err;
>> +    }
>> +    /* Update group configuration */
>> +    throttle_group_config(tgm, &cfg);
>> +
>> +    ret = 0;
>> +    goto fin;
>> +
>> +err:
>> +    ret = -EINVAL;
>> +fin:
>> +    qemu_opts_del(opts);
>> +    return ret;
>> +}
>> +
>> +static int throttle_open(BlockDriverState *bs, QDict *options,
>> +                            int flags, Error **errp)
>> +{
>> +    ThrottleGroupMember *tgm = bs->opaque;
>> +
>> +    bs->file = bdrv_open_child(NULL, options, "file",
>> +                                    bs, &child_file, false, errp);
>
>Indentation is off.
>
>> +    if (!bs->file) {
>> +        return -EINVAL;
>> +    }
>> +
>> +    return throttle_configure_tgm(bs, tgm, options, errp);
>> +}
>> +
>> +static void throttle_close(BlockDriverState *bs)
>> +{
>> +    ThrottleGroupMember *tgm = bs->opaque;
>> +    throttle_group_unregister_tgm(tgm);
>> +}
>> +
>> +
>> +static int64_t throttle_getlength(BlockDriverState *bs)
>> +{
>> +    return bdrv_getlength(bs->file->bs);
>> +}
>> +
>> +
>> +static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
>> +                                           uint64_t offset, uint64_t bytes,
>> +                                           QEMUIOVector *qiov, int flags)
>> +{
>> +
>> +    ThrottleGroupMember *tgm = bs->opaque;
>> +    throttle_group_co_io_limits_intercept(tgm, bytes, false);
>> +
>> +    return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
>> +}
>> +
>> +static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
>> +                                            uint64_t offset, uint64_t bytes,
>> +                                            QEMUIOVector *qiov, int flags)
>> +{
>> +    ThrottleGroupMember *tgm = bs->opaque;
>> +    throttle_group_co_io_limits_intercept(tgm, bytes, true);
>> +
>> +    return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
>> +}
>
>I think we want to set BlockDriver.supported_write_flags so that passing
>down flags is actually of any use.

Can you explain what you mean? Do you mean doing this in 
throttle_open():

    bs->supported_write_flags = bs->file->bs->supported_write_flags;
    bs->supported_zero_flags = bs->file->bs->supported_zero_flags;
>
>> +
>> +static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
>> +        int64_t offset, int bytes, BdrvRequestFlags flags)
>> +{
>> +    ThrottleGroupMember *tgm = bs->opaque;
>> +    throttle_group_co_io_limits_intercept(tgm, bytes, true);
>> +
>> +    return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
>> +}
>
>The same is true for BlockDriver.supported_zero_flags.
>
>> +static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
>> +        int64_t offset, int bytes)
>> +{
>> +    ThrottleGroupMember *tgm = bs->opaque;
>> +    throttle_group_co_io_limits_intercept(tgm, bytes, true);
>> +
>> +    return bdrv_co_pdiscard(bs->file->bs, offset, bytes);
>> +}
>> +
>> +static int throttle_co_flush(BlockDriverState *bs)
>> +{
>> +    return bdrv_co_flush(bs->file->bs);
>> +}
>> +
>> +static void throttle_detach_aio_context(BlockDriverState *bs)
>> +{
>> +    ThrottleGroupMember *tgm = bs->opaque;
>> +    throttle_group_detach_aio_context(tgm);
>> +}
>> +
>> +static void throttle_attach_aio_context(BlockDriverState *bs,
>> +                                    AioContext *new_context)
>
>Indentation is off here...
>
>> +{
>> +    ThrottleGroupMember *tgm = bs->opaque;
>> +    throttle_group_attach_aio_context(tgm, new_context);
>> +}
>> +
>> +static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
>> +                                      BlockReopenQueue *queue, Error **errp)
>
>...and here.
>
>> +{
>> +    ThrottleGroupMember *tgm = NULL;
>> +
>> +    assert(reopen_state != NULL);
>> +    assert(reopen_state->bs != NULL);
>> +
>> +    reopen_state->opaque = g_new0(ThrottleGroupMember, 1);
>> +    tgm = reopen_state->opaque;
>> +
>> +    return throttle_configure_tgm(reopen_state->bs, tgm, reopen_state->options,
>> +            errp);
>> +}
>> +
>> +static void throttle_reopen_commit(BDRVReopenState *state)
>> +{
>> +    ThrottleGroupMember *tgm = state->bs->opaque;
>> +
>> +    throttle_group_unregister_tgm(tgm);
>> +    g_free(state->bs->opaque);
>> +    state->bs->opaque = state->opaque;
>> +    state->opaque = NULL;
>> +}
>> +
>> +static void throttle_reopen_abort(BDRVReopenState *state)
>> +{
>> +    ThrottleGroupMember *tgm = state->opaque;
>> +
>> +    throttle_group_unregister_tgm(tgm);
>> +    g_free(state->opaque);
>> +    state->opaque = NULL;
>> +}
>> +
>> +static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,
>> +                                                 BlockDriverState *candidate)
>> +{
>> +    return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
>> +}
>> +
>> +static BlockDriver bdrv_throttle = {
>> +    .format_name                        =   "throttle",
>> +    .protocol_name                      =   "throttle",
>> +    .instance_size                      =   sizeof(ThrottleGroupMember),
>> +
>> +    .bdrv_file_open                     =   throttle_open,
>> +    .bdrv_close                         =   throttle_close,
>> +    .bdrv_co_flush                      =   throttle_co_flush,
>> +
>> +    .bdrv_child_perm                    =   bdrv_filter_default_perms,
>> +
>> +    .bdrv_getlength                     =   throttle_getlength,
>> +
>> +    .bdrv_co_preadv                     =   throttle_co_preadv,
>> +    .bdrv_co_pwritev                    =   throttle_co_pwritev,
>> +
>> +    .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
>> +    .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
>> +
>> +    .bdrv_recurse_is_first_non_filter   =   throttle_recurse_is_first_non_filter,
>> +
>> +    .bdrv_attach_aio_context            =   throttle_attach_aio_context,
>> +    .bdrv_detach_aio_context            =   throttle_detach_aio_context,
>> +
>> +    .bdrv_reopen_prepare                =   throttle_reopen_prepare,
>> +    .bdrv_reopen_commit                 =   throttle_reopen_commit,
>> +    .bdrv_reopen_abort                  =   throttle_reopen_abort,
>> +
>> +    .is_filter                          =   true,
>> +};
>
>What about .bdrv_co_get_block_status?

We should use the default implementation here that you merged into your 
2.11 tree, thanks for noticing and for all the comments.
>
>> +static void bdrv_throttle_init(void)
>> +{
>> +    bdrv_register(&bdrv_throttle);
>> +}
>> +
>> +block_init(bdrv_throttle_init);
>> diff --git a/include/qemu/throttle-options.h b/include/qemu/throttle-options.h
>> index 182b7896e1..3528a8f4a2 100644
>> --- a/include/qemu/throttle-options.h
>> +++ b/include/qemu/throttle-options.h
>> @@ -29,6 +29,7 @@
>>  #define QEMU_OPT_BPS_WRITE_MAX "bps-write-max"
>>  #define QEMU_OPT_BPS_WRITE_MAX_LENGTH "bps-write-max-length"
>>  #define QEMU_OPT_IOPS_SIZE "iops-size"
>> +#define QEMU_OPT_THROTTLE_GROUP_NAME "throttle-group"
>>
>>  #define THROTTLE_OPT_PREFIX "throttling."
>>  #define THROTTLE_OPTS \
>
>Kevin
>