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OpenCloudOS-Kernel/block/blk-cgroup.c

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/*
* Common Block IO controller cgroup interface
*
* Based on ideas and code from CFQ, CFS and BFQ:
* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
*
* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
* Paolo Valente <paolo.valente@unimore.it>
*
* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
* Nauman Rafique <nauman@google.com>
*/
#include <linux/ioprio.h>
#include <linux/seq_file.h>
#include <linux/kdev_t.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/genhd.h>
#include <linux/delay.h>
#include <linux/atomic.h>
#include "blk-cgroup.h"
#include "blk.h"
#define MAX_KEY_LEN 100
static DEFINE_SPINLOCK(blkio_list_lock);
static LIST_HEAD(blkio_list);
static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);
/* List of groups pending per cpu stats allocation */
static DEFINE_SPINLOCK(alloc_list_lock);
static LIST_HEAD(alloc_list);
static void blkio_stat_alloc_fn(struct work_struct *);
static DECLARE_DELAYED_WORK(blkio_stat_alloc_work, blkio_stat_alloc_fn);
struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
EXPORT_SYMBOL_GPL(blkio_root_cgroup);
static struct blkio_policy_type *blkio_policy[BLKIO_NR_POLICIES];
/* for encoding cft->private value on file */
#define BLKIOFILE_PRIVATE(x, val) (((x) << 16) | (val))
/* What policy owns the file, proportional or throttle */
#define BLKIOFILE_POLICY(val) (((val) >> 16) & 0xffff)
#define BLKIOFILE_ATTR(val) ((val) & 0xffff)
struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
{
return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
struct blkio_cgroup, css);
}
EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
static struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk)
{
return container_of(task_subsys_state(tsk, blkio_subsys_id),
struct blkio_cgroup, css);
}
struct blkio_cgroup *bio_blkio_cgroup(struct bio *bio)
{
if (bio && bio->bi_css)
return container_of(bio->bi_css, struct blkio_cgroup, css);
return task_blkio_cgroup(current);
}
EXPORT_SYMBOL_GPL(bio_blkio_cgroup);
static inline void blkio_update_group_weight(struct blkio_group *blkg,
int plid, unsigned int weight)
{
struct blkio_policy_type *blkiop;
list_for_each_entry(blkiop, &blkio_list, list) {
/* If this policy does not own the blkg, do not send updates */
if (blkiop->plid != plid)
continue;
if (blkiop->ops.blkio_update_group_weight_fn)
blkiop->ops.blkio_update_group_weight_fn(blkg->q,
blkg, weight);
}
}
static inline void blkio_update_group_bps(struct blkio_group *blkg, int plid,
u64 bps, int fileid)
{
struct blkio_policy_type *blkiop;
list_for_each_entry(blkiop, &blkio_list, list) {
/* If this policy does not own the blkg, do not send updates */
if (blkiop->plid != plid)
continue;
if (fileid == BLKIO_THROTL_read_bps_device
&& blkiop->ops.blkio_update_group_read_bps_fn)
blkiop->ops.blkio_update_group_read_bps_fn(blkg->q,
blkg, bps);
if (fileid == BLKIO_THROTL_write_bps_device
&& blkiop->ops.blkio_update_group_write_bps_fn)
blkiop->ops.blkio_update_group_write_bps_fn(blkg->q,
blkg, bps);
}
}
static inline void blkio_update_group_iops(struct blkio_group *blkg,
int plid, unsigned int iops,
int fileid)
{
struct blkio_policy_type *blkiop;
list_for_each_entry(blkiop, &blkio_list, list) {
/* If this policy does not own the blkg, do not send updates */
if (blkiop->plid != plid)
continue;
if (fileid == BLKIO_THROTL_read_iops_device
&& blkiop->ops.blkio_update_group_read_iops_fn)
blkiop->ops.blkio_update_group_read_iops_fn(blkg->q,
blkg, iops);
if (fileid == BLKIO_THROTL_write_iops_device
&& blkiop->ops.blkio_update_group_write_iops_fn)
blkiop->ops.blkio_update_group_write_iops_fn(blkg->q,
blkg,iops);
}
}
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* This should be called with the queue_lock held. */
static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
struct blkio_policy_type *pol,
struct blkio_group *curr_blkg)
{
struct blkg_policy_data *pd = blkg->pd[pol->plid];
if (blkio_blkg_waiting(&pd->stats))
return;
if (blkg == curr_blkg)
return;
pd->stats.start_group_wait_time = sched_clock();
blkio_mark_blkg_waiting(&pd->stats);
}
/* This should be called with the queue_lock held. */
static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
{
unsigned long long now;
if (!blkio_blkg_waiting(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_group_wait_time))
blkg_stat_add(&stats->group_wait_time,
now - stats->start_group_wait_time);
blkio_clear_blkg_waiting(stats);
}
/* This should be called with the queue_lock held. */
static void blkio_end_empty_time(struct blkio_group_stats *stats)
{
unsigned long long now;
if (!blkio_blkg_empty(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_empty_time))
blkg_stat_add(&stats->empty_time,
now - stats->start_empty_time);
blkio_clear_blkg_empty(stats);
}
void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
lockdep_assert_held(blkg->q->queue_lock);
BUG_ON(blkio_blkg_idling(stats));
stats->start_idle_time = sched_clock();
blkio_mark_blkg_idling(stats);
}
EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);
void blkiocg_update_idle_time_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
lockdep_assert_held(blkg->q->queue_lock);
if (blkio_blkg_idling(stats)) {
unsigned long long now = sched_clock();
if (time_after64(now, stats->start_idle_time))
blkg_stat_add(&stats->idle_time,
now - stats->start_idle_time);
blkio_clear_blkg_idling(stats);
}
}
EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);
void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
lockdep_assert_held(blkg->q->queue_lock);
blkg_stat_add(&stats->avg_queue_size_sum,
blkg_rwstat_sum(&stats->queued));
blkg_stat_add(&stats->avg_queue_size_samples, 1);
blkio_update_group_wait_time(stats);
}
EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);
void blkiocg_set_start_empty_time(struct blkio_group *blkg,
struct blkio_policy_type *pol)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
lockdep_assert_held(blkg->q->queue_lock);
if (blkg_rwstat_sum(&stats->queued))
return;
/*
* group is already marked empty. This can happen if cfqq got new
* request in parent group and moved to this group while being added
* to service tree. Just ignore the event and move on.
*/
if (blkio_blkg_empty(stats))
return;
stats->start_empty_time = sched_clock();
blkio_mark_blkg_empty(stats);
}
EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol,
unsigned long dequeue)
{
struct blkg_policy_data *pd = blkg->pd[pol->plid];
lockdep_assert_held(blkg->q->queue_lock);
blkg_stat_add(&pd->stats.dequeue, dequeue);
}
EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
#else
static inline void blkio_set_start_group_wait_time(struct blkio_group *blkg,
struct blkio_policy_type *pol,
struct blkio_group *curr_blkg) { }
static inline void blkio_end_empty_time(struct blkio_group_stats *stats) { }
#endif
void blkiocg_update_io_add_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol,
struct blkio_group *curr_blkg, bool direction,
bool sync)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);
lockdep_assert_held(blkg->q->queue_lock);
blkg_rwstat_add(&stats->queued, rw, 1);
blkio_end_empty_time(stats);
blkio_set_start_group_wait_time(blkg, pol, curr_blkg);
}
EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol,
bool direction, bool sync)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);
lockdep_assert_held(blkg->q->queue_lock);
blkg_rwstat_add(&stats->queued, rw, -1);
}
EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
void blkiocg_update_timeslice_used(struct blkio_group *blkg,
struct blkio_policy_type *pol,
unsigned long time,
unsigned long unaccounted_time)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
lockdep_assert_held(blkg->q->queue_lock);
blkg_stat_add(&stats->time, time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_add(&stats->unaccounted_time, unaccounted_time);
#endif
}
EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
/*
* should be called under rcu read lock or queue lock to make sure blkg pointer
* is valid.
*/
void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol,
uint64_t bytes, bool direction, bool sync)
{
int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);
struct blkg_policy_data *pd = blkg->pd[pol->plid];
struct blkio_group_stats_cpu *stats_cpu;
unsigned long flags;
/* If per cpu stats are not allocated yet, don't do any accounting. */
if (pd->stats_cpu == NULL)
return;
/*
* Disabling interrupts to provide mutual exclusion between two
* writes on same cpu. It probably is not needed for 64bit. Not
* optimizing that case yet.
*/
local_irq_save(flags);
stats_cpu = this_cpu_ptr(pd->stats_cpu);
blkg_stat_add(&stats_cpu->sectors, bytes >> 9);
blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
void blkiocg_update_completion_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol,
uint64_t start_time,
uint64_t io_start_time, bool direction,
bool sync)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
unsigned long long now = sched_clock();
int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);
lockdep_assert_held(blkg->q->queue_lock);
if (time_after64(now, io_start_time))
blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
if (time_after64(io_start_time, start_time))
blkg_rwstat_add(&stats->wait_time, rw,
io_start_time - start_time);
}
EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
/* Merged stats are per cpu. */
void blkiocg_update_io_merged_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol,
bool direction, bool sync)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);
lockdep_assert_held(blkg->q->queue_lock);
blkg_rwstat_add(&stats->merged, rw, 1);
}
EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
/*
* Worker for allocating per cpu stat for blk groups. This is scheduled on
* the system_nrt_wq once there are some groups on the alloc_list waiting
* for allocation.
*/
static void blkio_stat_alloc_fn(struct work_struct *work)
{
static void *pcpu_stats[BLKIO_NR_POLICIES];
struct delayed_work *dwork = to_delayed_work(work);
struct blkio_group *blkg;
int i;
bool empty = false;
alloc_stats:
for (i = 0; i < BLKIO_NR_POLICIES; i++) {
if (pcpu_stats[i] != NULL)
continue;
pcpu_stats[i] = alloc_percpu(struct blkio_group_stats_cpu);
/* Allocation failed. Try again after some time. */
if (pcpu_stats[i] == NULL) {
queue_delayed_work(system_nrt_wq, dwork,
msecs_to_jiffies(10));
return;
}
}
spin_lock_irq(&blkio_list_lock);
spin_lock(&alloc_list_lock);
/* cgroup got deleted or queue exited. */
if (!list_empty(&alloc_list)) {
blkg = list_first_entry(&alloc_list, struct blkio_group,
alloc_node);
for (i = 0; i < BLKIO_NR_POLICIES; i++) {
struct blkg_policy_data *pd = blkg->pd[i];
if (blkio_policy[i] && pd && !pd->stats_cpu)
swap(pd->stats_cpu, pcpu_stats[i]);
}
list_del_init(&blkg->alloc_node);
}
empty = list_empty(&alloc_list);
spin_unlock(&alloc_list_lock);
spin_unlock_irq(&blkio_list_lock);
if (!empty)
goto alloc_stats;
}
/**
* blkg_free - free a blkg
* @blkg: blkg to free
*
* Free @blkg which may be partially allocated.
*/
static void blkg_free(struct blkio_group *blkg)
{
int i;
if (!blkg)
return;
for (i = 0; i < BLKIO_NR_POLICIES; i++) {
struct blkg_policy_data *pd = blkg->pd[i];
if (pd) {
free_percpu(pd->stats_cpu);
kfree(pd);
}
}
kfree(blkg);
}
/**
* blkg_alloc - allocate a blkg
* @blkcg: block cgroup the new blkg is associated with
* @q: request_queue the new blkg is associated with
*
* Allocate a new blkg assocating @blkcg and @q.
*/
static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg,
struct request_queue *q)
{
struct blkio_group *blkg;
int i;
/* alloc and init base part */
blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node);
if (!blkg)
return NULL;
blkg->q = q;
INIT_LIST_HEAD(&blkg->q_node);
INIT_LIST_HEAD(&blkg->alloc_node);
blkg->blkcg = blkcg;
blkg->refcnt = 1;
cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
for (i = 0; i < BLKIO_NR_POLICIES; i++) {
struct blkio_policy_type *pol = blkio_policy[i];
struct blkg_policy_data *pd;
if (!pol)
continue;
/* alloc per-policy data and attach it to blkg */
pd = kzalloc_node(sizeof(*pd) + pol->pdata_size, GFP_ATOMIC,
q->node);
if (!pd) {
blkg_free(blkg);
return NULL;
}
blkg->pd[i] = pd;
pd->blkg = blkg;
}
/* invoke per-policy init */
for (i = 0; i < BLKIO_NR_POLICIES; i++) {
struct blkio_policy_type *pol = blkio_policy[i];
if (pol)
pol->ops.blkio_init_group_fn(blkg);
}
return blkg;
}
struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg,
struct request_queue *q,
bool for_root)
__releases(q->queue_lock) __acquires(q->queue_lock)
{
struct blkio_group *blkg;
WARN_ON_ONCE(!rcu_read_lock_held());
lockdep_assert_held(q->queue_lock);
/*
* This could be the first entry point of blkcg implementation and
* we shouldn't allow anything to go through for a bypassing queue.
* The following can be removed if blkg lookup is guaranteed to
* fail on a bypassing queue.
*/
if (unlikely(blk_queue_bypass(q)) && !for_root)
return ERR_PTR(blk_queue_dead(q) ? -EINVAL : -EBUSY);
blkg = blkg_lookup(blkcg, q);
if (blkg)
return blkg;
/* blkg holds a reference to blkcg */
if (!css_tryget(&blkcg->css))
return ERR_PTR(-EINVAL);
/*
* Allocate and initialize.
*/
blkg = blkg_alloc(blkcg, q);
/* did alloc fail? */
if (unlikely(!blkg)) {
blkg = ERR_PTR(-ENOMEM);
goto out;
}
/* insert */
spin_lock(&blkcg->lock);
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
list_add(&blkg->q_node, &q->blkg_list);
spin_unlock(&blkcg->lock);
spin_lock(&alloc_list_lock);
list_add(&blkg->alloc_node, &alloc_list);
/* Queue per cpu stat allocation from worker thread. */
queue_delayed_work(system_nrt_wq, &blkio_stat_alloc_work, 0);
spin_unlock(&alloc_list_lock);
out:
return blkg;
}
EXPORT_SYMBOL_GPL(blkg_lookup_create);
/* called under rcu_read_lock(). */
struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
struct request_queue *q)
{
struct blkio_group *blkg;
struct hlist_node *n;
hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node)
if (blkg->q == q)
return blkg;
return NULL;
}
EXPORT_SYMBOL_GPL(blkg_lookup);
static void blkg_destroy(struct blkio_group *blkg)
{
struct request_queue *q = blkg->q;
struct blkio_cgroup *blkcg = blkg->blkcg;
lockdep_assert_held(q->queue_lock);
lockdep_assert_held(&blkcg->lock);
/* Something wrong if we are trying to remove same group twice */
WARN_ON_ONCE(list_empty(&blkg->q_node));
WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
list_del_init(&blkg->q_node);
hlist_del_init_rcu(&blkg->blkcg_node);
spin_lock(&alloc_list_lock);
list_del_init(&blkg->alloc_node);
spin_unlock(&alloc_list_lock);
/*
* Put the reference taken at the time of creation so that when all
* queues are gone, group can be destroyed.
*/
blkg_put(blkg);
}
/*
* XXX: This updates blkg policy data in-place for root blkg, which is
* necessary across elevator switch and policy registration as root blkgs
* aren't shot down. This broken and racy implementation is temporary.
* Eventually, blkg shoot down will be replaced by proper in-place update.
*/
void update_root_blkg_pd(struct request_queue *q, enum blkio_policy_id plid)
{
struct blkio_policy_type *pol = blkio_policy[plid];
struct blkio_group *blkg = blkg_lookup(&blkio_root_cgroup, q);
struct blkg_policy_data *pd;
if (!blkg)
return;
kfree(blkg->pd[plid]);
blkg->pd[plid] = NULL;
if (!pol)
return;
pd = kzalloc(sizeof(*pd) + pol->pdata_size, GFP_KERNEL);
WARN_ON_ONCE(!pd);
pd->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu);
WARN_ON_ONCE(!pd->stats_cpu);
blkg->pd[plid] = pd;
pd->blkg = blkg;
pol->ops.blkio_init_group_fn(blkg);
}
EXPORT_SYMBOL_GPL(update_root_blkg_pd);
/**
* blkg_destroy_all - destroy all blkgs associated with a request_queue
* @q: request_queue of interest
* @destroy_root: whether to destroy root blkg or not
*
* Destroy blkgs associated with @q. If @destroy_root is %true, all are
* destroyed; otherwise, root blkg is left alone.
*/
void blkg_destroy_all(struct request_queue *q, bool destroy_root)
{
struct blkio_group *blkg, *n;
spin_lock_irq(q->queue_lock);
list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
struct blkio_cgroup *blkcg = blkg->blkcg;
/* skip root? */
if (!destroy_root && blkg->blkcg == &blkio_root_cgroup)
continue;
spin_lock(&blkcg->lock);
blkg_destroy(blkg);
spin_unlock(&blkcg->lock);
}
spin_unlock_irq(q->queue_lock);
}
EXPORT_SYMBOL_GPL(blkg_destroy_all);
static void blkg_rcu_free(struct rcu_head *rcu_head)
{
blkg_free(container_of(rcu_head, struct blkio_group, rcu_head));
}
void __blkg_release(struct blkio_group *blkg)
{
/* release the extra blkcg reference this blkg has been holding */
css_put(&blkg->blkcg->css);
/*
* A group is freed in rcu manner. But having an rcu lock does not
* mean that one can access all the fields of blkg and assume these
* are valid. For example, don't try to follow throtl_data and
* request queue links.
*
* Having a reference to blkg under an rcu allows acess to only
* values local to groups like group stats and group rate limits
*/
call_rcu(&blkg->rcu_head, blkg_rcu_free);
}
EXPORT_SYMBOL_GPL(__blkg_release);
static void blkio_reset_stats_cpu(struct blkio_group *blkg, int plid)
{
struct blkg_policy_data *pd = blkg->pd[plid];
int cpu;
if (pd->stats_cpu == NULL)
return;
for_each_possible_cpu(cpu) {
struct blkio_group_stats_cpu *sc =
per_cpu_ptr(pd->stats_cpu, cpu);
blkg_rwstat_reset(&sc->service_bytes);
blkg_rwstat_reset(&sc->serviced);
blkg_stat_reset(&sc->sectors);
}
}
static int
blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
struct blkio_group *blkg;
struct hlist_node *n;
spin_lock(&blkio_list_lock);
spin_lock_irq(&blkcg->lock);
/*
* Note that stat reset is racy - it doesn't synchronize against
* stat updates. This is a debug feature which shouldn't exist
* anyway. If you get hit by a race, retry.
*/
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
struct blkio_policy_type *pol;
list_for_each_entry(pol, &blkio_list, list) {
struct blkg_policy_data *pd = blkg->pd[pol->plid];
struct blkio_group_stats *stats = &pd->stats;
/* queued stats shouldn't be cleared */
blkg_rwstat_reset(&stats->merged);
blkg_rwstat_reset(&stats->service_time);
blkg_rwstat_reset(&stats->wait_time);
blkg_stat_reset(&stats->time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_reset(&stats->unaccounted_time);
blkg_stat_reset(&stats->avg_queue_size_sum);
blkg_stat_reset(&stats->avg_queue_size_samples);
blkg_stat_reset(&stats->dequeue);
blkg_stat_reset(&stats->group_wait_time);
blkg_stat_reset(&stats->idle_time);
blkg_stat_reset(&stats->empty_time);
#endif
blkio_reset_stats_cpu(blkg, pol->plid);
}
}
spin_unlock_irq(&blkcg->lock);
spin_unlock(&blkio_list_lock);
return 0;
}
static const char *blkg_dev_name(struct blkio_group *blkg)
{
/* some drivers (floppy) instantiate a queue w/o disk registered */
if (blkg->q->backing_dev_info.dev)
return dev_name(blkg->q->backing_dev_info.dev);
return NULL;
}
/**
* blkcg_print_blkgs - helper for printing per-blkg data
* @sf: seq_file to print to
* @blkcg: blkcg of interest
* @prfill: fill function to print out a blkg
* @pol: policy in question
* @data: data to be passed to @prfill
* @show_total: to print out sum of prfill return values or not
*
* This function invokes @prfill on each blkg of @blkcg if pd for the
* policy specified by @pol exists. @prfill is invoked with @sf, the
* policy data and @data. If @show_total is %true, the sum of the return
* values from @prfill is printed with "Total" label at the end.
*
* This is to be used to construct print functions for
* cftype->read_seq_string method.
*/
static void blkcg_print_blkgs(struct seq_file *sf, struct blkio_cgroup *blkcg,
u64 (*prfill)(struct seq_file *,
struct blkg_policy_data *, int),
int pol, int data, bool show_total)
{
struct blkio_group *blkg;
struct hlist_node *n;
u64 total = 0;
spin_lock_irq(&blkcg->lock);
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
if (blkg->pd[pol])
total += prfill(sf, blkg->pd[pol], data);
spin_unlock_irq(&blkcg->lock);
if (show_total)
seq_printf(sf, "Total %llu\n", (unsigned long long)total);
}
/**
* __blkg_prfill_u64 - prfill helper for a single u64 value
* @sf: seq_file to print to
* @pd: policy data of interest
* @v: value to print
*
* Print @v to @sf for the device assocaited with @pd.
*/
static u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd,
u64 v)
{
const char *dname = blkg_dev_name(pd->blkg);
if (!dname)
return 0;
seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v);
return v;
}
/**
* __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
* @sf: seq_file to print to
* @pd: policy data of interest
* @rwstat: rwstat to print
*
* Print @rwstat to @sf for the device assocaited with @pd.
*/
static u64 __blkg_prfill_rwstat(struct seq_file *sf,
struct blkg_policy_data *pd,
const struct blkg_rwstat *rwstat)
{
static const char *rwstr[] = {
[BLKG_RWSTAT_READ] = "Read",
[BLKG_RWSTAT_WRITE] = "Write",
[BLKG_RWSTAT_SYNC] = "Sync",
[BLKG_RWSTAT_ASYNC] = "Async",
};
const char *dname = blkg_dev_name(pd->blkg);
u64 v;
int i;
if (!dname)
return 0;
for (i = 0; i < BLKG_RWSTAT_NR; i++)
seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
(unsigned long long)rwstat->cnt[i]);
v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE];
seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
return v;
}
static u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd,
int off)
{
return __blkg_prfill_u64(sf, pd,
blkg_stat_read((void *)&pd->stats + off));
}
static u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
int off)
{
struct blkg_rwstat rwstat = blkg_rwstat_read((void *)&pd->stats + off);
return __blkg_prfill_rwstat(sf, pd, &rwstat);
}
/* print blkg_stat specified by BLKCG_STAT_PRIV() */
static int blkcg_print_stat(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat,
BLKCG_STAT_POL(cft->private),
BLKCG_STAT_OFF(cft->private), false);
return 0;
}
/* print blkg_rwstat specified by BLKCG_STAT_PRIV() */
static int blkcg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat,
BLKCG_STAT_POL(cft->private),
BLKCG_STAT_OFF(cft->private), true);
return 0;
}
static u64 blkg_prfill_cpu_stat(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
u64 v = 0;
int cpu;
for_each_possible_cpu(cpu) {
struct blkio_group_stats_cpu *sc =
per_cpu_ptr(pd->stats_cpu, cpu);
v += blkg_stat_read((void *)sc + off);
}
return __blkg_prfill_u64(sf, pd, v);
}
static u64 blkg_prfill_cpu_rwstat(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct blkg_rwstat rwstat = { }, tmp;
int i, cpu;
for_each_possible_cpu(cpu) {
struct blkio_group_stats_cpu *sc =
per_cpu_ptr(pd->stats_cpu, cpu);
tmp = blkg_rwstat_read((void *)sc + off);
for (i = 0; i < BLKG_RWSTAT_NR; i++)
rwstat.cnt[i] += tmp.cnt[i];
}
return __blkg_prfill_rwstat(sf, pd, &rwstat);
}
/* print per-cpu blkg_stat specified by BLKCG_STAT_PRIV() */
static int blkcg_print_cpu_stat(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_stat,
BLKCG_STAT_POL(cft->private),
BLKCG_STAT_OFF(cft->private), false);
return 0;
}
/* print per-cpu blkg_rwstat specified by BLKCG_STAT_PRIV() */
static int blkcg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_rwstat,
BLKCG_STAT_POL(cft->private),
BLKCG_STAT_OFF(cft->private), true);
return 0;
}
#ifdef CONFIG_DEBUG_BLK_CGROUP
static u64 blkg_prfill_avg_queue_size(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
u64 samples = blkg_stat_read(&pd->stats.avg_queue_size_samples);
u64 v = 0;
if (samples) {
v = blkg_stat_read(&pd->stats.avg_queue_size_sum);
do_div(v, samples);
}
__blkg_prfill_u64(sf, pd, v);
return 0;
}
/* print avg_queue_size */
static int blkcg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
blkcg_print_blkgs(sf, blkcg, blkg_prfill_avg_queue_size,
BLKIO_POLICY_PROP, 0, false);
return 0;
}
#endif /* CONFIG_DEBUG_BLK_CGROUP */
static int blkio_policy_parse_and_set(char *buf, enum blkio_policy_id plid,
int fileid, struct blkio_cgroup *blkcg)
{
struct gendisk *disk = NULL;
struct blkio_group *blkg = NULL;
struct blkg_policy_data *pd;
char *s[4], *p, *major_s = NULL, *minor_s = NULL;
unsigned long major, minor;
int i = 0, ret = -EINVAL;
int part;
dev_t dev;
u64 temp;
memset(s, 0, sizeof(s));
while ((p = strsep(&buf, " ")) != NULL) {
if (!*p)
continue;
s[i++] = p;
/* Prevent from inputing too many things */
if (i == 3)
break;
}
if (i != 2)
goto out;
p = strsep(&s[0], ":");
if (p != NULL)
major_s = p;
else
goto out;
minor_s = s[0];
if (!minor_s)
goto out;
if (strict_strtoul(major_s, 10, &major))
goto out;
if (strict_strtoul(minor_s, 10, &minor))
goto out;
dev = MKDEV(major, minor);
if (strict_strtoull(s[1], 10, &temp))
goto out;
disk = get_gendisk(dev, &part);
if (!disk || part)
goto out;
rcu_read_lock();
spin_lock_irq(disk->queue->queue_lock);
blkg = blkg_lookup_create(blkcg, disk->queue, false);
spin_unlock_irq(disk->queue->queue_lock);
if (IS_ERR(blkg)) {
ret = PTR_ERR(blkg);
goto out_unlock;
}
pd = blkg->pd[plid];
switch (plid) {
case BLKIO_POLICY_PROP:
if ((temp < BLKIO_WEIGHT_MIN && temp > 0) ||
temp > BLKIO_WEIGHT_MAX)
goto out_unlock;
pd->conf.weight = temp;
blkio_update_group_weight(blkg, plid, temp ?: blkcg->weight);
break;
case BLKIO_POLICY_THROTL:
switch(fileid) {
case BLKIO_THROTL_read_bps_device:
pd->conf.bps[READ] = temp;
blkio_update_group_bps(blkg, plid, temp ?: -1, fileid);
break;
case BLKIO_THROTL_write_bps_device:
pd->conf.bps[WRITE] = temp;
blkio_update_group_bps(blkg, plid, temp ?: -1, fileid);
break;
case BLKIO_THROTL_read_iops_device:
if (temp > THROTL_IOPS_MAX)
goto out_unlock;
pd->conf.iops[READ] = temp;
blkio_update_group_iops(blkg, plid, temp ?: -1, fileid);
break;
case BLKIO_THROTL_write_iops_device:
if (temp > THROTL_IOPS_MAX)
goto out_unlock;
pd->conf.iops[WRITE] = temp;
blkio_update_group_iops(blkg, plid, temp ?: -1, fileid);
break;
}
break;
default:
BUG();
}
ret = 0;
out_unlock:
rcu_read_unlock();
out:
put_disk(disk);
/*
* If queue was bypassing, we should retry. Do so after a short
* msleep(). It isn't strictly necessary but queue can be
* bypassing for some time and it's always nice to avoid busy
* looping.
*/
if (ret == -EBUSY) {
msleep(10);
return restart_syscall();
}
return ret;
}
static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
const char *buffer)
{
int ret = 0;
char *buf;
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
int fileid = BLKIOFILE_ATTR(cft->private);
buf = kstrdup(buffer, GFP_KERNEL);
if (!buf)
return -ENOMEM;
ret = blkio_policy_parse_and_set(buf, plid, fileid, blkcg);
kfree(buf);
return ret;
}
static void blkio_print_group_conf(struct cftype *cft, struct blkio_group *blkg,
struct seq_file *m)
{
int plid = BLKIOFILE_POLICY(cft->private);
int fileid = BLKIOFILE_ATTR(cft->private);
struct blkg_policy_data *pd = blkg->pd[plid];
const char *dname = blkg_dev_name(blkg);
int rw = WRITE;
if (!dname)
return;
switch (plid) {
case BLKIO_POLICY_PROP:
if (pd->conf.weight)
seq_printf(m, "%s\t%u\n",
dname, pd->conf.weight);
break;
case BLKIO_POLICY_THROTL:
switch (fileid) {
case BLKIO_THROTL_read_bps_device:
rw = READ;
case BLKIO_THROTL_write_bps_device:
if (pd->conf.bps[rw])
seq_printf(m, "%s\t%llu\n",
dname, pd->conf.bps[rw]);
break;
case BLKIO_THROTL_read_iops_device:
rw = READ;
case BLKIO_THROTL_write_iops_device:
if (pd->conf.iops[rw])
seq_printf(m, "%s\t%u\n",
dname, pd->conf.iops[rw]);
break;
}
break;
default:
BUG();
}
}
/* cgroup files which read their data from policy nodes end up here */
static void blkio_read_conf(struct cftype *cft, struct blkio_cgroup *blkcg,
struct seq_file *m)
{
struct blkio_group *blkg;
struct hlist_node *n;
spin_lock_irq(&blkcg->lock);
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
blkio_print_group_conf(cft, blkg, m);
spin_unlock_irq(&blkcg->lock);
}
static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *m)
{
struct blkio_cgroup *blkcg;
enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
int name = BLKIOFILE_ATTR(cft->private);
blkcg = cgroup_to_blkio_cgroup(cgrp);
switch(plid) {
case BLKIO_POLICY_PROP:
switch(name) {
case BLKIO_PROP_weight_device:
blkio_read_conf(cft, blkcg, m);
return 0;
default:
BUG();
}
break;
case BLKIO_POLICY_THROTL:
switch(name){
case BLKIO_THROTL_read_bps_device:
case BLKIO_THROTL_write_bps_device:
case BLKIO_THROTL_read_iops_device:
case BLKIO_THROTL_write_iops_device:
blkio_read_conf(cft, blkcg, m);
return 0;
default:
BUG();
}
break;
default:
BUG();
}
return 0;
}
static int blkio_weight_write(struct blkio_cgroup *blkcg, int plid, u64 val)
{
struct blkio_group *blkg;
struct hlist_node *n;
if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
return -EINVAL;
spin_lock(&blkio_list_lock);
spin_lock_irq(&blkcg->lock);
blkcg->weight = (unsigned int)val;
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
struct blkg_policy_data *pd = blkg->pd[plid];
if (!pd->conf.weight)
blkio_update_group_weight(blkg, plid, blkcg->weight);
}
spin_unlock_irq(&blkcg->lock);
spin_unlock(&blkio_list_lock);
return 0;
}
static u64 blkiocg_file_read_u64 (struct cgroup *cgrp, struct cftype *cft) {
struct blkio_cgroup *blkcg;
enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
int name = BLKIOFILE_ATTR(cft->private);
blkcg = cgroup_to_blkio_cgroup(cgrp);
switch(plid) {
case BLKIO_POLICY_PROP:
switch(name) {
case BLKIO_PROP_weight:
return (u64)blkcg->weight;
}
break;
default:
BUG();
}
return 0;
}
static int
blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
{
struct blkio_cgroup *blkcg;
enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
int name = BLKIOFILE_ATTR(cft->private);
blkcg = cgroup_to_blkio_cgroup(cgrp);
switch(plid) {
case BLKIO_POLICY_PROP:
switch(name) {
case BLKIO_PROP_weight:
return blkio_weight_write(blkcg, plid, val);
}
break;
default:
BUG();
}
return 0;
}
struct cftype blkio_files[] = {
{
.name = "weight_device",
.private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
BLKIO_PROP_weight_device),
.read_seq_string = blkiocg_file_read,
.write_string = blkiocg_file_write,
.max_write_len = 256,
},
{
.name = "weight",
.private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
BLKIO_PROP_weight),
.read_u64 = blkiocg_file_read_u64,
.write_u64 = blkiocg_file_write_u64,
},
{
.name = "time",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, time)),
.read_seq_string = blkcg_print_stat,
},
{
.name = "sectors",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats_cpu, sectors)),
.read_seq_string = blkcg_print_cpu_stat,
},
{
.name = "io_service_bytes",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats_cpu, service_bytes)),
.read_seq_string = blkcg_print_cpu_rwstat,
},
{
.name = "io_serviced",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats_cpu, serviced)),
.read_seq_string = blkcg_print_cpu_rwstat,
},
{
.name = "io_service_time",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, service_time)),
.read_seq_string = blkcg_print_rwstat,
},
{
.name = "io_wait_time",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, wait_time)),
.read_seq_string = blkcg_print_rwstat,
},
{
.name = "io_merged",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, merged)),
.read_seq_string = blkcg_print_rwstat,
},
{
.name = "io_queued",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, queued)),
.read_seq_string = blkcg_print_rwstat,
},
{
.name = "reset_stats",
.write_u64 = blkiocg_reset_stats,
},
#ifdef CONFIG_BLK_DEV_THROTTLING
{
.name = "throttle.read_bps_device",
.private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
BLKIO_THROTL_read_bps_device),
.read_seq_string = blkiocg_file_read,
.write_string = blkiocg_file_write,
.max_write_len = 256,
},
{
.name = "throttle.write_bps_device",
.private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
BLKIO_THROTL_write_bps_device),
.read_seq_string = blkiocg_file_read,
.write_string = blkiocg_file_write,
.max_write_len = 256,
},
{
.name = "throttle.read_iops_device",
.private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
BLKIO_THROTL_read_iops_device),
.read_seq_string = blkiocg_file_read,
.write_string = blkiocg_file_write,
.max_write_len = 256,
},
{
.name = "throttle.write_iops_device",
.private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
BLKIO_THROTL_write_iops_device),
.read_seq_string = blkiocg_file_read,
.write_string = blkiocg_file_write,
.max_write_len = 256,
},
{
.name = "throttle.io_service_bytes",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_THROTL,
offsetof(struct blkio_group_stats_cpu, service_bytes)),
.read_seq_string = blkcg_print_cpu_rwstat,
},
{
.name = "throttle.io_serviced",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_THROTL,
offsetof(struct blkio_group_stats_cpu, serviced)),
.read_seq_string = blkcg_print_cpu_rwstat,
},
#endif /* CONFIG_BLK_DEV_THROTTLING */
#ifdef CONFIG_DEBUG_BLK_CGROUP
{
.name = "avg_queue_size",
.read_seq_string = blkcg_print_avg_queue_size,
},
{
.name = "group_wait_time",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, group_wait_time)),
.read_seq_string = blkcg_print_stat,
},
{
.name = "idle_time",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, idle_time)),
.read_seq_string = blkcg_print_stat,
},
{
.name = "empty_time",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, empty_time)),
.read_seq_string = blkcg_print_stat,
},
{
.name = "dequeue",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, dequeue)),
.read_seq_string = blkcg_print_stat,
},
{
.name = "unaccounted_time",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
offsetof(struct blkio_group_stats, unaccounted_time)),
.read_seq_string = blkcg_print_stat,
},
#endif
{ } /* terminate */
};
/**
* blkiocg_pre_destroy - cgroup pre_destroy callback
* @cgroup: cgroup of interest
*
* This function is called when @cgroup is about to go away and responsible
* for shooting down all blkgs associated with @cgroup. blkgs should be
* removed while holding both q and blkcg locks. As blkcg lock is nested
* inside q lock, this function performs reverse double lock dancing.
*
* This is the blkcg counterpart of ioc_release_fn().
*/
static int blkiocg_pre_destroy(struct cgroup *cgroup)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
spin_lock_irq(&blkcg->lock);
while (!hlist_empty(&blkcg->blkg_list)) {
struct blkio_group *blkg = hlist_entry(blkcg->blkg_list.first,
struct blkio_group, blkcg_node);
struct request_queue *q = blkg->q;
if (spin_trylock(q->queue_lock)) {
blkg_destroy(blkg);
spin_unlock(q->queue_lock);
} else {
spin_unlock_irq(&blkcg->lock);
cpu_relax();
spin_lock_irq(&blkcg->lock);
}
}
spin_unlock_irq(&blkcg->lock);
return 0;
}
static void blkiocg_destroy(struct cgroup *cgroup)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
if (blkcg != &blkio_root_cgroup)
kfree(blkcg);
}
static struct cgroup_subsys_state *blkiocg_create(struct cgroup *cgroup)
{
static atomic64_t id_seq = ATOMIC64_INIT(0);
struct blkio_cgroup *blkcg;
struct cgroup *parent = cgroup->parent;
if (!parent) {
blkcg = &blkio_root_cgroup;
goto done;
}
blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
if (!blkcg)
return ERR_PTR(-ENOMEM);
blkcg->weight = BLKIO_WEIGHT_DEFAULT;
blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */
done:
spin_lock_init(&blkcg->lock);
INIT_HLIST_HEAD(&blkcg->blkg_list);
return &blkcg->css;
}
/**
* blkcg_init_queue - initialize blkcg part of request queue
* @q: request_queue to initialize
*
* Called from blk_alloc_queue_node(). Responsible for initializing blkcg
* part of new request_queue @q.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
int blkcg_init_queue(struct request_queue *q)
{
int ret;
might_sleep();
ret = blk_throtl_init(q);
if (ret)
return ret;
mutex_lock(&all_q_mutex);
INIT_LIST_HEAD(&q->all_q_node);
list_add_tail(&q->all_q_node, &all_q_list);
mutex_unlock(&all_q_mutex);
return 0;
}
/**
* blkcg_drain_queue - drain blkcg part of request_queue
* @q: request_queue to drain
*
* Called from blk_drain_queue(). Responsible for draining blkcg part.
*/
void blkcg_drain_queue(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
blk_throtl_drain(q);
}
/**
* blkcg_exit_queue - exit and release blkcg part of request_queue
* @q: request_queue being released
*
* Called from blk_release_queue(). Responsible for exiting blkcg part.
*/
void blkcg_exit_queue(struct request_queue *q)
{
mutex_lock(&all_q_mutex);
list_del_init(&q->all_q_node);
mutex_unlock(&all_q_mutex);
blkg_destroy_all(q, true);
blk_throtl_exit(q);
}
/*
* We cannot support shared io contexts, as we have no mean to support
* two tasks with the same ioc in two different groups without major rework
* of the main cic data structures. For now we allow a task to change
* its cgroup only if it's the only owner of its ioc.
*/
static int blkiocg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
struct task_struct *task;
struct io_context *ioc;
int ret = 0;
/* task_lock() is needed to avoid races with exit_io_context() */
cgroup_taskset_for_each(task, cgrp, tset) {
task_lock(task);
ioc = task->io_context;
if (ioc && atomic_read(&ioc->nr_tasks) > 1)
ret = -EINVAL;
task_unlock(task);
if (ret)
break;
}
return ret;
}
static void blkcg_bypass_start(void)
__acquires(&all_q_mutex)
{
struct request_queue *q;
mutex_lock(&all_q_mutex);
list_for_each_entry(q, &all_q_list, all_q_node) {
blk_queue_bypass_start(q);
blkg_destroy_all(q, false);
}
}
static void blkcg_bypass_end(void)
__releases(&all_q_mutex)
{
struct request_queue *q;
list_for_each_entry(q, &all_q_list, all_q_node)
blk_queue_bypass_end(q);
mutex_unlock(&all_q_mutex);
}
struct cgroup_subsys blkio_subsys = {
.name = "blkio",
.create = blkiocg_create,
.can_attach = blkiocg_can_attach,
.pre_destroy = blkiocg_pre_destroy,
.destroy = blkiocg_destroy,
.subsys_id = blkio_subsys_id,
.base_cftypes = blkio_files,
.module = THIS_MODULE,
};
EXPORT_SYMBOL_GPL(blkio_subsys);
void blkio_policy_register(struct blkio_policy_type *blkiop)
{
struct request_queue *q;
blkcg_bypass_start();
spin_lock(&blkio_list_lock);
BUG_ON(blkio_policy[blkiop->plid]);
blkio_policy[blkiop->plid] = blkiop;
list_add_tail(&blkiop->list, &blkio_list);
spin_unlock(&blkio_list_lock);
list_for_each_entry(q, &all_q_list, all_q_node)
update_root_blkg_pd(q, blkiop->plid);
blkcg_bypass_end();
}
EXPORT_SYMBOL_GPL(blkio_policy_register);
void blkio_policy_unregister(struct blkio_policy_type *blkiop)
{
struct request_queue *q;
blkcg_bypass_start();
spin_lock(&blkio_list_lock);
BUG_ON(blkio_policy[blkiop->plid] != blkiop);
blkio_policy[blkiop->plid] = NULL;
list_del_init(&blkiop->list);
spin_unlock(&blkio_list_lock);
list_for_each_entry(q, &all_q_list, all_q_node)
update_root_blkg_pd(q, blkiop->plid);
blkcg_bypass_end();
}
EXPORT_SYMBOL_GPL(blkio_policy_unregister);
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