LXR linux/block/blk-cgroup-fc-appid.c

   1// SPDX-License-Identifier: GPL-2.0
   2
   3#include "blk-cgroup.h"
   4
   5/**
   6 * blkcg_set_fc_appid - set the fc_app_id field associted to blkcg
   7 * @app_id: application identifier
   8 * @cgrp_id: cgroup id
   9 * @app_id_len: size of application identifier
  10 */
  11int blkcg_set_fc_appid(char *app_id, u64 cgrp_id, size_t app_id_len)
  12{
  13        struct cgroup *cgrp;
  14        struct cgroup_subsys_state *css;
  15        struct blkcg *blkcg;
  16        int ret  = 0;
  17
  18        if (app_id_len > FC_APPID_LEN)
  19                return -EINVAL;
  20
  21        cgrp = cgroup_get_from_id(cgrp_id);
  22        if (IS_ERR(cgrp))
  23                return PTR_ERR(cgrp);
  24        css = cgroup_get_e_css(cgrp, &io_cgrp_subsys);
  25        if (!css) {
  26                ret = -ENOENT;
  27                goto out_cgrp_put;
  28        }
  29        blkcg = css_to_blkcg(css);
  30        /*
  31         * There is a slight race condition on setting the appid.
  32         * Worst case an I/O may not find the right id.
  33         * This is no different from the I/O we let pass while obtaining
  34         * the vmid from the fabric.
  35         * Adding the overhead of a lock is not necessary.
  36         */
  37        strscpy(blkcg->fc_app_id, app_id, app_id_len);
  38        css_put(css);
  39out_cgrp_put:
  40        cgroup_put(cgrp);
  41        return ret;
  42}
  43EXPORT_SYMBOL_GPL(blkcg_set_fc_appid);
  44
  45/**
  46 * blkcg_get_fc_appid - get the fc app identifier associated with a bio
  47 * @bio: target bio
  48 *
  49 * On success return the fc_app_id, on failure return NULL
  50 */
  51char *blkcg_get_fc_appid(struct bio *bio)
  52{
  53        if (!bio->bi_blkg || bio->bi_blkg->blkcg->fc_app_id[0] == '\0')
  54                return NULL;
  55        return bio->bi_blkg->blkcg->fc_app_id;
  56}
  57EXPORT_SYMBOL_GPL(blkcg_get_fc_appid);
  58