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