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 */
11 int 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);
39 out_cgrp_put:
40 cgroup_put(cgrp);
41 return ret;
42 }
43 EXPORT_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 */
51 char *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 }
57 EXPORT_SYMBOL_GPL(blkcg_get_fc_appid);
58
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