270 lines
6.5 KiB
C
270 lines
6.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Block rq-qos policy for assigning an I/O priority class to requests.
|
|
*
|
|
* Using an rq-qos policy for assigning I/O priority class has two advantages
|
|
* over using the ioprio_set() system call:
|
|
*
|
|
* - This policy is cgroup based so it has all the advantages of cgroups.
|
|
* - While ioprio_set() does not affect page cache writeback I/O, this rq-qos
|
|
* controller affects page cache writeback I/O for filesystems that support
|
|
* assiociating a cgroup with writeback I/O. See also
|
|
* Documentation/admin-guide/cgroup-v2.rst.
|
|
*/
|
|
|
|
#include <linux/blk-mq.h>
|
|
#include <linux/blk_types.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include "blk-cgroup.h"
|
|
#include "blk-ioprio.h"
|
|
#include "blk-rq-qos.h"
|
|
|
|
/**
|
|
* enum prio_policy - I/O priority class policy.
|
|
* @POLICY_NO_CHANGE: (default) do not modify the I/O priority class.
|
|
* @POLICY_NONE_TO_RT: modify IOPRIO_CLASS_NONE into IOPRIO_CLASS_RT.
|
|
* @POLICY_RESTRICT_TO_BE: modify IOPRIO_CLASS_NONE and IOPRIO_CLASS_RT into
|
|
* IOPRIO_CLASS_BE.
|
|
* @POLICY_ALL_TO_IDLE: change the I/O priority class into IOPRIO_CLASS_IDLE.
|
|
*
|
|
* See also <linux/ioprio.h>.
|
|
*/
|
|
enum prio_policy {
|
|
POLICY_NO_CHANGE = 0,
|
|
POLICY_NONE_TO_RT = 1,
|
|
POLICY_RESTRICT_TO_BE = 2,
|
|
POLICY_ALL_TO_IDLE = 3,
|
|
};
|
|
|
|
static const char *policy_name[] = {
|
|
[POLICY_NO_CHANGE] = "no-change",
|
|
[POLICY_NONE_TO_RT] = "none-to-rt",
|
|
[POLICY_RESTRICT_TO_BE] = "restrict-to-be",
|
|
[POLICY_ALL_TO_IDLE] = "idle",
|
|
};
|
|
|
|
static struct blkcg_policy ioprio_policy;
|
|
|
|
/**
|
|
* struct ioprio_blkg - Per (cgroup, request queue) data.
|
|
* @pd: blkg_policy_data structure.
|
|
*/
|
|
struct ioprio_blkg {
|
|
struct blkg_policy_data pd;
|
|
};
|
|
|
|
/**
|
|
* struct ioprio_blkcg - Per cgroup data.
|
|
* @cpd: blkcg_policy_data structure.
|
|
* @prio_policy: One of the IOPRIO_CLASS_* values. See also <linux/ioprio.h>.
|
|
*/
|
|
struct ioprio_blkcg {
|
|
struct blkcg_policy_data cpd;
|
|
enum prio_policy prio_policy;
|
|
bool prio_set;
|
|
};
|
|
|
|
static inline struct ioprio_blkg *pd_to_ioprio(struct blkg_policy_data *pd)
|
|
{
|
|
return pd ? container_of(pd, struct ioprio_blkg, pd) : NULL;
|
|
}
|
|
|
|
static struct ioprio_blkcg *blkcg_to_ioprio_blkcg(struct blkcg *blkcg)
|
|
{
|
|
return container_of(blkcg_to_cpd(blkcg, &ioprio_policy),
|
|
struct ioprio_blkcg, cpd);
|
|
}
|
|
|
|
static struct ioprio_blkcg *
|
|
ioprio_blkcg_from_css(struct cgroup_subsys_state *css)
|
|
{
|
|
return blkcg_to_ioprio_blkcg(css_to_blkcg(css));
|
|
}
|
|
|
|
static struct ioprio_blkcg *ioprio_blkcg_from_bio(struct bio *bio)
|
|
{
|
|
struct blkg_policy_data *pd = blkg_to_pd(bio->bi_blkg, &ioprio_policy);
|
|
|
|
if (!pd)
|
|
return NULL;
|
|
|
|
return blkcg_to_ioprio_blkcg(pd->blkg->blkcg);
|
|
}
|
|
|
|
static int ioprio_show_prio_policy(struct seq_file *sf, void *v)
|
|
{
|
|
struct ioprio_blkcg *blkcg = ioprio_blkcg_from_css(seq_css(sf));
|
|
|
|
seq_printf(sf, "%s\n", policy_name[blkcg->prio_policy]);
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t ioprio_set_prio_policy(struct kernfs_open_file *of, char *buf,
|
|
size_t nbytes, loff_t off)
|
|
{
|
|
struct ioprio_blkcg *blkcg = ioprio_blkcg_from_css(of_css(of));
|
|
int ret;
|
|
|
|
if (off != 0)
|
|
return -EIO;
|
|
/* kernfs_fop_write_iter() terminates 'buf' with '\0'. */
|
|
ret = sysfs_match_string(policy_name, buf);
|
|
if (ret < 0)
|
|
return ret;
|
|
blkcg->prio_policy = ret;
|
|
blkcg->prio_set = true;
|
|
return nbytes;
|
|
}
|
|
|
|
static struct blkg_policy_data *
|
|
ioprio_alloc_pd(gfp_t gfp, struct request_queue *q, struct blkcg *blkcg)
|
|
{
|
|
struct ioprio_blkg *ioprio_blkg;
|
|
|
|
ioprio_blkg = kzalloc(sizeof(*ioprio_blkg), gfp);
|
|
if (!ioprio_blkg)
|
|
return NULL;
|
|
|
|
return &ioprio_blkg->pd;
|
|
}
|
|
|
|
static void ioprio_free_pd(struct blkg_policy_data *pd)
|
|
{
|
|
struct ioprio_blkg *ioprio_blkg = pd_to_ioprio(pd);
|
|
|
|
kfree(ioprio_blkg);
|
|
}
|
|
|
|
static struct blkcg_policy_data *ioprio_alloc_cpd(gfp_t gfp)
|
|
{
|
|
struct ioprio_blkcg *blkcg;
|
|
|
|
blkcg = kzalloc(sizeof(*blkcg), gfp);
|
|
if (!blkcg)
|
|
return NULL;
|
|
blkcg->prio_policy = POLICY_NO_CHANGE;
|
|
return &blkcg->cpd;
|
|
}
|
|
|
|
static void ioprio_free_cpd(struct blkcg_policy_data *cpd)
|
|
{
|
|
struct ioprio_blkcg *blkcg = container_of(cpd, typeof(*blkcg), cpd);
|
|
|
|
kfree(blkcg);
|
|
}
|
|
|
|
#define IOPRIO_ATTRS \
|
|
{ \
|
|
.name = "prio.class", \
|
|
.seq_show = ioprio_show_prio_policy, \
|
|
.write = ioprio_set_prio_policy, \
|
|
}, \
|
|
{ } /* sentinel */
|
|
|
|
/* cgroup v2 attributes */
|
|
static struct cftype ioprio_files[] = {
|
|
IOPRIO_ATTRS
|
|
};
|
|
|
|
/* cgroup v1 attributes */
|
|
static struct cftype ioprio_legacy_files[] = {
|
|
IOPRIO_ATTRS
|
|
};
|
|
|
|
static struct blkcg_policy ioprio_policy = {
|
|
.dfl_cftypes = ioprio_files,
|
|
.legacy_cftypes = ioprio_legacy_files,
|
|
|
|
.cpd_alloc_fn = ioprio_alloc_cpd,
|
|
.cpd_free_fn = ioprio_free_cpd,
|
|
|
|
.pd_alloc_fn = ioprio_alloc_pd,
|
|
.pd_free_fn = ioprio_free_pd,
|
|
};
|
|
|
|
struct blk_ioprio {
|
|
struct rq_qos rqos;
|
|
};
|
|
|
|
static void blkcg_ioprio_track(struct rq_qos *rqos, struct request *rq,
|
|
struct bio *bio)
|
|
{
|
|
struct ioprio_blkcg *blkcg = ioprio_blkcg_from_bio(bio);
|
|
u16 prio;
|
|
|
|
if (!blkcg->prio_set)
|
|
return;
|
|
|
|
/*
|
|
* Except for IOPRIO_CLASS_NONE, higher I/O priority numbers
|
|
* correspond to a lower priority. Hence, the max_t() below selects
|
|
* the lower priority of bi_ioprio and the cgroup I/O priority class.
|
|
* If the cgroup policy has been set to POLICY_NO_CHANGE == 0, the
|
|
* bio I/O priority is not modified. If the bio I/O priority equals
|
|
* IOPRIO_CLASS_NONE, the cgroup I/O priority is assigned to the bio.
|
|
*/
|
|
prio = max_t(u16, bio->bi_ioprio,
|
|
IOPRIO_PRIO_VALUE(blkcg->prio_policy, 0));
|
|
if (prio > bio->bi_ioprio)
|
|
bio->bi_ioprio = prio;
|
|
}
|
|
|
|
static void blkcg_ioprio_exit(struct rq_qos *rqos)
|
|
{
|
|
struct blk_ioprio *blkioprio_blkg =
|
|
container_of(rqos, typeof(*blkioprio_blkg), rqos);
|
|
|
|
blkcg_deactivate_policy(rqos->q, &ioprio_policy);
|
|
kfree(blkioprio_blkg);
|
|
}
|
|
|
|
static struct rq_qos_ops blkcg_ioprio_ops = {
|
|
.track = blkcg_ioprio_track,
|
|
.exit = blkcg_ioprio_exit,
|
|
};
|
|
|
|
int blk_ioprio_init(struct request_queue *q)
|
|
{
|
|
struct blk_ioprio *blkioprio_blkg;
|
|
struct rq_qos *rqos;
|
|
int ret;
|
|
|
|
blkioprio_blkg = kzalloc(sizeof(*blkioprio_blkg), GFP_KERNEL);
|
|
if (!blkioprio_blkg)
|
|
return -ENOMEM;
|
|
|
|
ret = blkcg_activate_policy(q, &ioprio_policy);
|
|
if (ret) {
|
|
kfree(blkioprio_blkg);
|
|
return ret;
|
|
}
|
|
|
|
rqos = &blkioprio_blkg->rqos;
|
|
rqos->id = RQ_QOS_IOPRIO;
|
|
rqos->ops = &blkcg_ioprio_ops;
|
|
rqos->q = q;
|
|
|
|
/*
|
|
* Registering the rq-qos policy after activating the blk-cgroup
|
|
* policy guarantees that ioprio_blkcg_from_bio(bio) != NULL in the
|
|
* rq-qos callbacks.
|
|
*/
|
|
rq_qos_add(q, rqos);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __init ioprio_init(void)
|
|
{
|
|
return blkcg_policy_register(&ioprio_policy);
|
|
}
|
|
|
|
static void __exit ioprio_exit(void)
|
|
{
|
|
blkcg_policy_unregister(&ioprio_policy);
|
|
}
|
|
|
|
module_init(ioprio_init);
|
|
module_exit(ioprio_exit);
|