// SPDX-License-Identifier: GPL-2.0

#include "blk-cgroup.h"

/**
 * blkcg_set_fc_appid - set the fc_app_id field associted to blkcg
 * @app_id: application identifier
 * @cgrp_id: cgroup id
 * @app_id_len: size of application identifier
 */
int blkcg_set_fc_appid(char *app_id, u64 cgrp_id, size_t app_id_len)
{
        struct cgroup *cgrp;
        struct cgroup_subsys_state *css;
        struct blkcg *blkcg;
        int ret  = 0;

        if (app_id_len > FC_APPID_LEN)
                return -EINVAL;

        cgrp = cgroup_get_from_id(cgrp_id);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);
        css = cgroup_get_e_css(cgrp, &io_cgrp_subsys);
        if (!css) {
                ret = -ENOENT;
                goto out_cgrp_put;
        }
        blkcg = css_to_blkcg(css);
        /*
         * There is a slight race condition on setting the appid.
         * Worst case an I/O may not find the right id.
         * This is no different from the I/O we let pass while obtaining
         * the vmid from the fabric.
         * Adding the overhead of a lock is not necessary.
         */
        strscpy(blkcg->fc_app_id, app_id, app_id_len);
        css_put(css);
out_cgrp_put:
        cgroup_put(cgrp);
        return ret;
}
EXPORT_SYMBOL_GPL(blkcg_set_fc_appid);

/**
 * blkcg_get_fc_appid - get the fc app identifier associated with a bio
 * @bio: target bio
 *
 * On success return the fc_app_id, on failure return NULL
 */
char *blkcg_get_fc_appid(struct bio *bio)
{
        if (!bio->bi_blkg || bio->bi_blkg->blkcg->fc_app_id[0] == '\0')
                return NULL;
        return bio->bi_blkg->blkcg->fc_app_id;
}
EXPORT_SYMBOL_GPL(blkcg_get_fc_appid);