linux-stable/block/blk-cgroup-fc-appid.c
Michal Koutný fa7e439cf9 cgroup: Homogenize cgroup_get_from_id() return value
Cgroup id is user provided datum hence extend its return domain to
include possible error reason (similar to cgroup_get_from_fd()).

This change also fixes commit d4ccaf58a8 ("bpf: Introduce cgroup
iter") that would use NULL instead of proper error handling in
d4ccaf58a8 ("bpf: Introduce cgroup iter").

Additionally, neither of: fc_appid_store, bpf_iter_attach_cgroup,
mem_cgroup_get_from_ino (callers of cgroup_get_from_fd) is built without
CONFIG_CGROUPS (depends via CONFIG_BLK_CGROUP, direct, transitive
CONFIG_MEMCG respectively) transitive, so drop the singular definition
not needed with !CONFIG_CGROUPS.

Fixes: d4ccaf58a8 ("bpf: Introduce cgroup iter")
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2022-08-26 10:57:41 -10:00

57 lines
1.4 KiB
C

// 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.
*/
strlcpy(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);