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Re: [lvm-devel] [PATCH] lvm2app: Add thin and thin pool lv creation V2



Tony Asleson <tasleson redhat com> writes:

> + *
> + */
> +lv_create_params_t lvm_lv_params_create_thin_pool(vg_t vg,
> +		const char *pool_name, uint64_t size, uint32_t chunk_size,
> +		uint64_t meta_size, lvm_thin_discards_t discard);
> +
> +#define lvm_lv_params_create_thin_pool_default(vg, pool_name, size) \
> +			lvm_lv_params_create_thin_pool((vg), (pool_name), (size), 0, 0, \
> +			LVM_THIN_DISCARDS_PASSDOWN)
> +
> +
> +/**
> + * Set the value of zero skip for the lv_create_params
> + *
> + * \param params
> + * lv_create_prams to change
> + *
> + * \param skip
> + * Value of skip zero to be set (0 == zero, 1 == skip zero)
> + *
> + * \return
> + * 0 on success, else -1
> + */
> +int lvm_lv_params_skip_zero_set(lv_create_params_t params, int skip);

Are we going to provide as many helper functions to get/set parameters
in lv_create_params structure? For example if an user does wants a new
LV to be created in deactivation state, should we provide a helper
something like this?

int lvm_lv_params_activation_set(lv_create_params_t params, int
activate);

In this case lvm-api wont be flooded with lots of helper functions?
Instead of individual helper function how about a common helper function
to take care of this?

int lvm_lv_params_set(lv_create_params_t params, enum lv_create_param_type,
                      type, void *data);

lvm_lv_params_set function will validate 'data' based on the
lv_create_param_type and will return error if 'data' does not match
given enum (resource)?

enum lv_create_param_type {
     LV_CR_INVALID,
     LV_CR_ZERO,
     LV_CR_ACTIVATION,

     LV_CR_MAX_PARAM,
};

In above zero case, this function will be invoked like this:

lvm_lv_params_set(params, LV_CR_ZERO, &zero);

lvm_lv_params_set will do:
                  switch (type) {
                  case LV_CR_ZERO:
                     memcpy (&zero_skip, data, sizeof(int));
                     break;
                  case LV_CR_ACTIVATION:
                       memcpy (&activation, data, sizeof(int));
                       if (activation < CHANGE_AY && activation >
                          CHANGE_AAY) {
                          log_error();
                          return -1;
                       }
                  }



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