![Marcos Paulo de Souza](/assets/img/avatar_default.png)
Since 4cf6324b17
, a portion of function blk_cleanup_queue was moved to
a newly created function called blk_exit_queue, including the call of
blkcg_exit_queue. So, adjust the documenation according.
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1786 lines
46 KiB
C
1786 lines
46 KiB
C
/*
|
|
* 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>
|
|
*
|
|
* For policy-specific per-blkcg data:
|
|
* Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
|
|
* Arianna Avanzini <avanzini.arianna@gmail.com>
|
|
*/
|
|
#include <linux/ioprio.h>
|
|
#include <linux/kdev_t.h>
|
|
#include <linux/module.h>
|
|
#include <linux/sched/signal.h>
|
|
#include <linux/err.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/backing-dev.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/genhd.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/atomic.h>
|
|
#include <linux/ctype.h>
|
|
#include <linux/blk-cgroup.h>
|
|
#include <linux/tracehook.h>
|
|
#include "blk.h"
|
|
|
|
#define MAX_KEY_LEN 100
|
|
|
|
/*
|
|
* blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation.
|
|
* blkcg_pol_register_mutex nests outside of it and synchronizes entire
|
|
* policy [un]register operations including cgroup file additions /
|
|
* removals. Putting cgroup file registration outside blkcg_pol_mutex
|
|
* allows grabbing it from cgroup callbacks.
|
|
*/
|
|
static DEFINE_MUTEX(blkcg_pol_register_mutex);
|
|
static DEFINE_MUTEX(blkcg_pol_mutex);
|
|
|
|
struct blkcg blkcg_root;
|
|
EXPORT_SYMBOL_GPL(blkcg_root);
|
|
|
|
struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css;
|
|
|
|
static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
|
|
|
|
static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */
|
|
|
|
static bool blkcg_debug_stats = false;
|
|
|
|
static bool blkcg_policy_enabled(struct request_queue *q,
|
|
const struct blkcg_policy *pol)
|
|
{
|
|
return pol && test_bit(pol->plid, q->blkcg_pols);
|
|
}
|
|
|
|
/**
|
|
* blkg_free - free a blkg
|
|
* @blkg: blkg to free
|
|
*
|
|
* Free @blkg which may be partially allocated.
|
|
*/
|
|
static void blkg_free(struct blkcg_gq *blkg)
|
|
{
|
|
int i;
|
|
|
|
if (!blkg)
|
|
return;
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++)
|
|
if (blkg->pd[i])
|
|
blkcg_policy[i]->pd_free_fn(blkg->pd[i]);
|
|
|
|
blkg_rwstat_exit(&blkg->stat_ios);
|
|
blkg_rwstat_exit(&blkg->stat_bytes);
|
|
kfree(blkg);
|
|
}
|
|
|
|
static void __blkg_release(struct rcu_head *rcu)
|
|
{
|
|
struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head);
|
|
|
|
percpu_ref_exit(&blkg->refcnt);
|
|
|
|
/* release the blkcg and parent blkg refs this blkg has been holding */
|
|
css_put(&blkg->blkcg->css);
|
|
if (blkg->parent)
|
|
blkg_put(blkg->parent);
|
|
|
|
wb_congested_put(blkg->wb_congested);
|
|
|
|
blkg_free(blkg);
|
|
}
|
|
|
|
/*
|
|
* A group is RCU protected, 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 accesses to only values
|
|
* local to groups like group stats and group rate limits.
|
|
*/
|
|
static void blkg_release(struct percpu_ref *ref)
|
|
{
|
|
struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt);
|
|
|
|
call_rcu(&blkg->rcu_head, __blkg_release);
|
|
}
|
|
|
|
/**
|
|
* blkg_alloc - allocate a blkg
|
|
* @blkcg: block cgroup the new blkg is associated with
|
|
* @q: request_queue the new blkg is associated with
|
|
* @gfp_mask: allocation mask to use
|
|
*
|
|
* Allocate a new blkg assocating @blkcg and @q.
|
|
*/
|
|
static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
|
|
gfp_t gfp_mask)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
int i;
|
|
|
|
/* alloc and init base part */
|
|
blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node);
|
|
if (!blkg)
|
|
return NULL;
|
|
|
|
if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) ||
|
|
blkg_rwstat_init(&blkg->stat_ios, gfp_mask))
|
|
goto err_free;
|
|
|
|
blkg->q = q;
|
|
INIT_LIST_HEAD(&blkg->q_node);
|
|
blkg->blkcg = blkcg;
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
struct blkg_policy_data *pd;
|
|
|
|
if (!blkcg_policy_enabled(q, pol))
|
|
continue;
|
|
|
|
/* alloc per-policy data and attach it to blkg */
|
|
pd = pol->pd_alloc_fn(gfp_mask, q->node);
|
|
if (!pd)
|
|
goto err_free;
|
|
|
|
blkg->pd[i] = pd;
|
|
pd->blkg = blkg;
|
|
pd->plid = i;
|
|
}
|
|
|
|
return blkg;
|
|
|
|
err_free:
|
|
blkg_free(blkg);
|
|
return NULL;
|
|
}
|
|
|
|
struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
|
|
struct request_queue *q, bool update_hint)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
|
|
/*
|
|
* Hint didn't match. Look up from the radix tree. Note that the
|
|
* hint can only be updated under queue_lock as otherwise @blkg
|
|
* could have already been removed from blkg_tree. The caller is
|
|
* responsible for grabbing queue_lock if @update_hint.
|
|
*/
|
|
blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
|
|
if (blkg && blkg->q == q) {
|
|
if (update_hint) {
|
|
lockdep_assert_held(&q->queue_lock);
|
|
rcu_assign_pointer(blkcg->blkg_hint, blkg);
|
|
}
|
|
return blkg;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_lookup_slowpath);
|
|
|
|
/*
|
|
* If @new_blkg is %NULL, this function tries to allocate a new one as
|
|
* necessary using %GFP_NOWAIT. @new_blkg is always consumed on return.
|
|
*/
|
|
static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
|
|
struct request_queue *q,
|
|
struct blkcg_gq *new_blkg)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
struct bdi_writeback_congested *wb_congested;
|
|
int i, ret;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
lockdep_assert_held(&q->queue_lock);
|
|
|
|
/* request_queue is dying, do not create/recreate a blkg */
|
|
if (blk_queue_dying(q)) {
|
|
ret = -ENODEV;
|
|
goto err_free_blkg;
|
|
}
|
|
|
|
/* blkg holds a reference to blkcg */
|
|
if (!css_tryget_online(&blkcg->css)) {
|
|
ret = -ENODEV;
|
|
goto err_free_blkg;
|
|
}
|
|
|
|
wb_congested = wb_congested_get_create(q->backing_dev_info,
|
|
blkcg->css.id,
|
|
GFP_NOWAIT | __GFP_NOWARN);
|
|
if (!wb_congested) {
|
|
ret = -ENOMEM;
|
|
goto err_put_css;
|
|
}
|
|
|
|
/* allocate */
|
|
if (!new_blkg) {
|
|
new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN);
|
|
if (unlikely(!new_blkg)) {
|
|
ret = -ENOMEM;
|
|
goto err_put_congested;
|
|
}
|
|
}
|
|
blkg = new_blkg;
|
|
blkg->wb_congested = wb_congested;
|
|
|
|
/* link parent */
|
|
if (blkcg_parent(blkcg)) {
|
|
blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
|
|
if (WARN_ON_ONCE(!blkg->parent)) {
|
|
ret = -ENODEV;
|
|
goto err_put_congested;
|
|
}
|
|
blkg_get(blkg->parent);
|
|
}
|
|
|
|
ret = percpu_ref_init(&blkg->refcnt, blkg_release, 0,
|
|
GFP_NOWAIT | __GFP_NOWARN);
|
|
if (ret)
|
|
goto err_cancel_ref;
|
|
|
|
/* invoke per-policy init */
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
|
|
if (blkg->pd[i] && pol->pd_init_fn)
|
|
pol->pd_init_fn(blkg->pd[i]);
|
|
}
|
|
|
|
/* insert */
|
|
spin_lock(&blkcg->lock);
|
|
ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
|
|
if (likely(!ret)) {
|
|
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
|
|
list_add(&blkg->q_node, &q->blkg_list);
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
|
|
if (blkg->pd[i] && pol->pd_online_fn)
|
|
pol->pd_online_fn(blkg->pd[i]);
|
|
}
|
|
}
|
|
blkg->online = true;
|
|
spin_unlock(&blkcg->lock);
|
|
|
|
if (!ret)
|
|
return blkg;
|
|
|
|
/* @blkg failed fully initialized, use the usual release path */
|
|
blkg_put(blkg);
|
|
return ERR_PTR(ret);
|
|
|
|
err_cancel_ref:
|
|
percpu_ref_exit(&blkg->refcnt);
|
|
err_put_congested:
|
|
wb_congested_put(wb_congested);
|
|
err_put_css:
|
|
css_put(&blkcg->css);
|
|
err_free_blkg:
|
|
blkg_free(new_blkg);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
/**
|
|
* __blkg_lookup_create - lookup blkg, try to create one if not there
|
|
* @blkcg: blkcg of interest
|
|
* @q: request_queue of interest
|
|
*
|
|
* Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
|
|
* create one. blkg creation is performed recursively from blkcg_root such
|
|
* that all non-root blkg's have access to the parent blkg. This function
|
|
* should be called under RCU read lock and @q->queue_lock.
|
|
*
|
|
* Returns the blkg or the closest blkg if blkg_create() fails as it walks
|
|
* down from root.
|
|
*/
|
|
struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
|
|
struct request_queue *q)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
lockdep_assert_held(&q->queue_lock);
|
|
|
|
blkg = __blkg_lookup(blkcg, q, true);
|
|
if (blkg)
|
|
return blkg;
|
|
|
|
/*
|
|
* Create blkgs walking down from blkcg_root to @blkcg, so that all
|
|
* non-root blkgs have access to their parents. Returns the closest
|
|
* blkg to the intended blkg should blkg_create() fail.
|
|
*/
|
|
while (true) {
|
|
struct blkcg *pos = blkcg;
|
|
struct blkcg *parent = blkcg_parent(blkcg);
|
|
struct blkcg_gq *ret_blkg = q->root_blkg;
|
|
|
|
while (parent) {
|
|
blkg = __blkg_lookup(parent, q, false);
|
|
if (blkg) {
|
|
/* remember closest blkg */
|
|
ret_blkg = blkg;
|
|
break;
|
|
}
|
|
pos = parent;
|
|
parent = blkcg_parent(parent);
|
|
}
|
|
|
|
blkg = blkg_create(pos, q, NULL);
|
|
if (IS_ERR(blkg))
|
|
return ret_blkg;
|
|
if (pos == blkcg)
|
|
return blkg;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* blkg_lookup_create - find or create a blkg
|
|
* @blkcg: target block cgroup
|
|
* @q: target request_queue
|
|
*
|
|
* This looks up or creates the blkg representing the unique pair
|
|
* of the blkcg and the request_queue.
|
|
*/
|
|
struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
|
|
struct request_queue *q)
|
|
{
|
|
struct blkcg_gq *blkg = blkg_lookup(blkcg, q);
|
|
|
|
if (unlikely(!blkg)) {
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&q->queue_lock, flags);
|
|
blkg = __blkg_lookup_create(blkcg, q);
|
|
spin_unlock_irqrestore(&q->queue_lock, flags);
|
|
}
|
|
|
|
return blkg;
|
|
}
|
|
|
|
static void blkg_destroy(struct blkcg_gq *blkg)
|
|
{
|
|
struct blkcg *blkcg = blkg->blkcg;
|
|
struct blkcg_gq *parent = blkg->parent;
|
|
int i;
|
|
|
|
lockdep_assert_held(&blkg->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));
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
|
|
if (blkg->pd[i] && pol->pd_offline_fn)
|
|
pol->pd_offline_fn(blkg->pd[i]);
|
|
}
|
|
|
|
if (parent) {
|
|
blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes);
|
|
blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios);
|
|
}
|
|
|
|
blkg->online = false;
|
|
|
|
radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
|
|
list_del_init(&blkg->q_node);
|
|
hlist_del_init_rcu(&blkg->blkcg_node);
|
|
|
|
/*
|
|
* Both setting lookup hint to and clearing it from @blkg are done
|
|
* under queue_lock. If it's not pointing to @blkg now, it never
|
|
* will. Hint assignment itself can race safely.
|
|
*/
|
|
if (rcu_access_pointer(blkcg->blkg_hint) == blkg)
|
|
rcu_assign_pointer(blkcg->blkg_hint, NULL);
|
|
|
|
/*
|
|
* Put the reference taken at the time of creation so that when all
|
|
* queues are gone, group can be destroyed.
|
|
*/
|
|
percpu_ref_kill(&blkg->refcnt);
|
|
}
|
|
|
|
/**
|
|
* blkg_destroy_all - destroy all blkgs associated with a request_queue
|
|
* @q: request_queue of interest
|
|
*
|
|
* Destroy all blkgs associated with @q.
|
|
*/
|
|
static void blkg_destroy_all(struct request_queue *q)
|
|
{
|
|
struct blkcg_gq *blkg, *n;
|
|
|
|
spin_lock_irq(&q->queue_lock);
|
|
list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
|
|
struct blkcg *blkcg = blkg->blkcg;
|
|
|
|
spin_lock(&blkcg->lock);
|
|
blkg_destroy(blkg);
|
|
spin_unlock(&blkcg->lock);
|
|
}
|
|
|
|
q->root_blkg = NULL;
|
|
spin_unlock_irq(&q->queue_lock);
|
|
}
|
|
|
|
static int blkcg_reset_stats(struct cgroup_subsys_state *css,
|
|
struct cftype *cftype, u64 val)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(css);
|
|
struct blkcg_gq *blkg;
|
|
int i;
|
|
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
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, &blkcg->blkg_list, blkcg_node) {
|
|
blkg_rwstat_reset(&blkg->stat_bytes);
|
|
blkg_rwstat_reset(&blkg->stat_ios);
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
|
|
if (blkg->pd[i] && pol->pd_reset_stats_fn)
|
|
pol->pd_reset_stats_fn(blkg->pd[i]);
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(&blkcg->lock);
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
return 0;
|
|
}
|
|
|
|
const char *blkg_dev_name(struct blkcg_gq *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 and the matching queue lock held. 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.
|
|
*/
|
|
void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
|
|
u64 (*prfill)(struct seq_file *,
|
|
struct blkg_policy_data *, int),
|
|
const struct blkcg_policy *pol, int data,
|
|
bool show_total)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
u64 total = 0;
|
|
|
|
rcu_read_lock();
|
|
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
|
|
spin_lock_irq(&blkg->q->queue_lock);
|
|
if (blkcg_policy_enabled(blkg->q, pol))
|
|
total += prfill(sf, blkg->pd[pol->plid], data);
|
|
spin_unlock_irq(&blkg->q->queue_lock);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
if (show_total)
|
|
seq_printf(sf, "Total %llu\n", (unsigned long long)total);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_print_blkgs);
|
|
|
|
/**
|
|
* __blkg_prfill_u64 - prfill helper for a single u64 value
|
|
* @sf: seq_file to print to
|
|
* @pd: policy private data of interest
|
|
* @v: value to print
|
|
*
|
|
* Print @v to @sf for the device assocaited with @pd.
|
|
*/
|
|
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;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
|
|
|
|
/**
|
|
* __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
|
|
* @sf: seq_file to print to
|
|
* @pd: policy private data of interest
|
|
* @rwstat: rwstat to print
|
|
*
|
|
* Print @rwstat to @sf for the device assocaited with @pd.
|
|
*/
|
|
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",
|
|
[BLKG_RWSTAT_DISCARD] = "Discard",
|
|
};
|
|
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)atomic64_read(&rwstat->aux_cnt[i]));
|
|
|
|
v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) +
|
|
atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]) +
|
|
atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_DISCARD]);
|
|
seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
|
|
return v;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
|
|
|
|
/**
|
|
* blkg_prfill_stat - prfill callback for blkg_stat
|
|
* @sf: seq_file to print to
|
|
* @pd: policy private data of interest
|
|
* @off: offset to the blkg_stat in @pd
|
|
*
|
|
* prfill callback for printing a blkg_stat.
|
|
*/
|
|
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 + off));
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_prfill_stat);
|
|
|
|
/**
|
|
* blkg_prfill_rwstat - prfill callback for blkg_rwstat
|
|
* @sf: seq_file to print to
|
|
* @pd: policy private data of interest
|
|
* @off: offset to the blkg_rwstat in @pd
|
|
*
|
|
* prfill callback for printing a blkg_rwstat.
|
|
*/
|
|
u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off);
|
|
|
|
return __blkg_prfill_rwstat(sf, pd, &rwstat);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
|
|
|
|
static u64 blkg_prfill_rwstat_field(struct seq_file *sf,
|
|
struct blkg_policy_data *pd, int off)
|
|
{
|
|
struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd->blkg + off);
|
|
|
|
return __blkg_prfill_rwstat(sf, pd, &rwstat);
|
|
}
|
|
|
|
/**
|
|
* blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes
|
|
* @sf: seq_file to print to
|
|
* @v: unused
|
|
*
|
|
* To be used as cftype->seq_show to print blkg->stat_bytes.
|
|
* cftype->private must be set to the blkcg_policy.
|
|
*/
|
|
int blkg_print_stat_bytes(struct seq_file *sf, void *v)
|
|
{
|
|
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
|
|
blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
|
|
offsetof(struct blkcg_gq, stat_bytes), true);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_print_stat_bytes);
|
|
|
|
/**
|
|
* blkg_print_stat_bytes - seq_show callback for blkg->stat_ios
|
|
* @sf: seq_file to print to
|
|
* @v: unused
|
|
*
|
|
* To be used as cftype->seq_show to print blkg->stat_ios. cftype->private
|
|
* must be set to the blkcg_policy.
|
|
*/
|
|
int blkg_print_stat_ios(struct seq_file *sf, void *v)
|
|
{
|
|
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
|
|
blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
|
|
offsetof(struct blkcg_gq, stat_ios), true);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_print_stat_ios);
|
|
|
|
static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf,
|
|
struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct blkg_rwstat rwstat = blkg_rwstat_recursive_sum(pd->blkg,
|
|
NULL, off);
|
|
return __blkg_prfill_rwstat(sf, pd, &rwstat);
|
|
}
|
|
|
|
/**
|
|
* blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes
|
|
* @sf: seq_file to print to
|
|
* @v: unused
|
|
*/
|
|
int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v)
|
|
{
|
|
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
|
|
blkg_prfill_rwstat_field_recursive,
|
|
(void *)seq_cft(sf)->private,
|
|
offsetof(struct blkcg_gq, stat_bytes), true);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive);
|
|
|
|
/**
|
|
* blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios
|
|
* @sf: seq_file to print to
|
|
* @v: unused
|
|
*/
|
|
int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v)
|
|
{
|
|
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
|
|
blkg_prfill_rwstat_field_recursive,
|
|
(void *)seq_cft(sf)->private,
|
|
offsetof(struct blkcg_gq, stat_ios), true);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive);
|
|
|
|
/**
|
|
* blkg_stat_recursive_sum - collect hierarchical blkg_stat
|
|
* @blkg: blkg of interest
|
|
* @pol: blkcg_policy which contains the blkg_stat
|
|
* @off: offset to the blkg_stat in blkg_policy_data or @blkg
|
|
*
|
|
* Collect the blkg_stat specified by @blkg, @pol and @off and all its
|
|
* online descendants and their aux counts. The caller must be holding the
|
|
* queue lock for online tests.
|
|
*
|
|
* If @pol is NULL, blkg_stat is at @off bytes into @blkg; otherwise, it is
|
|
* at @off bytes into @blkg's blkg_policy_data of the policy.
|
|
*/
|
|
u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
|
|
struct blkcg_policy *pol, int off)
|
|
{
|
|
struct blkcg_gq *pos_blkg;
|
|
struct cgroup_subsys_state *pos_css;
|
|
u64 sum = 0;
|
|
|
|
lockdep_assert_held(&blkg->q->queue_lock);
|
|
|
|
rcu_read_lock();
|
|
blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
|
|
struct blkg_stat *stat;
|
|
|
|
if (!pos_blkg->online)
|
|
continue;
|
|
|
|
if (pol)
|
|
stat = (void *)blkg_to_pd(pos_blkg, pol) + off;
|
|
else
|
|
stat = (void *)blkg + off;
|
|
|
|
sum += blkg_stat_read(stat) + atomic64_read(&stat->aux_cnt);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return sum;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
|
|
|
|
/**
|
|
* blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
|
|
* @blkg: blkg of interest
|
|
* @pol: blkcg_policy which contains the blkg_rwstat
|
|
* @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
|
|
*
|
|
* Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
|
|
* online descendants and their aux counts. The caller must be holding the
|
|
* queue lock for online tests.
|
|
*
|
|
* If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it
|
|
* is at @off bytes into @blkg's blkg_policy_data of the policy.
|
|
*/
|
|
struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
|
|
struct blkcg_policy *pol, int off)
|
|
{
|
|
struct blkcg_gq *pos_blkg;
|
|
struct cgroup_subsys_state *pos_css;
|
|
struct blkg_rwstat sum = { };
|
|
int i;
|
|
|
|
lockdep_assert_held(&blkg->q->queue_lock);
|
|
|
|
rcu_read_lock();
|
|
blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
|
|
struct blkg_rwstat *rwstat;
|
|
|
|
if (!pos_blkg->online)
|
|
continue;
|
|
|
|
if (pol)
|
|
rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
|
|
else
|
|
rwstat = (void *)pos_blkg + off;
|
|
|
|
for (i = 0; i < BLKG_RWSTAT_NR; i++)
|
|
atomic64_add(atomic64_read(&rwstat->aux_cnt[i]) +
|
|
percpu_counter_sum_positive(&rwstat->cpu_cnt[i]),
|
|
&sum.aux_cnt[i]);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return sum;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
|
|
|
|
/* Performs queue bypass and policy enabled checks then looks up blkg. */
|
|
static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg,
|
|
const struct blkcg_policy *pol,
|
|
struct request_queue *q)
|
|
{
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
lockdep_assert_held(&q->queue_lock);
|
|
|
|
if (!blkcg_policy_enabled(q, pol))
|
|
return ERR_PTR(-EOPNOTSUPP);
|
|
return __blkg_lookup(blkcg, q, true /* update_hint */);
|
|
}
|
|
|
|
/**
|
|
* blkg_conf_prep - parse and prepare for per-blkg config update
|
|
* @blkcg: target block cgroup
|
|
* @pol: target policy
|
|
* @input: input string
|
|
* @ctx: blkg_conf_ctx to be filled
|
|
*
|
|
* Parse per-blkg config update from @input and initialize @ctx with the
|
|
* result. @ctx->blkg points to the blkg to be updated and @ctx->body the
|
|
* part of @input following MAJ:MIN. This function returns with RCU read
|
|
* lock and queue lock held and must be paired with blkg_conf_finish().
|
|
*/
|
|
int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
|
|
char *input, struct blkg_conf_ctx *ctx)
|
|
__acquires(rcu) __acquires(&disk->queue->queue_lock)
|
|
{
|
|
struct gendisk *disk;
|
|
struct request_queue *q;
|
|
struct blkcg_gq *blkg;
|
|
unsigned int major, minor;
|
|
int key_len, part, ret;
|
|
char *body;
|
|
|
|
if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2)
|
|
return -EINVAL;
|
|
|
|
body = input + key_len;
|
|
if (!isspace(*body))
|
|
return -EINVAL;
|
|
body = skip_spaces(body);
|
|
|
|
disk = get_gendisk(MKDEV(major, minor), &part);
|
|
if (!disk)
|
|
return -ENODEV;
|
|
if (part) {
|
|
ret = -ENODEV;
|
|
goto fail;
|
|
}
|
|
|
|
q = disk->queue;
|
|
|
|
rcu_read_lock();
|
|
spin_lock_irq(&q->queue_lock);
|
|
|
|
blkg = blkg_lookup_check(blkcg, pol, q);
|
|
if (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
goto fail_unlock;
|
|
}
|
|
|
|
if (blkg)
|
|
goto success;
|
|
|
|
/*
|
|
* Create blkgs walking down from blkcg_root to @blkcg, so that all
|
|
* non-root blkgs have access to their parents.
|
|
*/
|
|
while (true) {
|
|
struct blkcg *pos = blkcg;
|
|
struct blkcg *parent;
|
|
struct blkcg_gq *new_blkg;
|
|
|
|
parent = blkcg_parent(blkcg);
|
|
while (parent && !__blkg_lookup(parent, q, false)) {
|
|
pos = parent;
|
|
parent = blkcg_parent(parent);
|
|
}
|
|
|
|
/* Drop locks to do new blkg allocation with GFP_KERNEL. */
|
|
spin_unlock_irq(&q->queue_lock);
|
|
rcu_read_unlock();
|
|
|
|
new_blkg = blkg_alloc(pos, q, GFP_KERNEL);
|
|
if (unlikely(!new_blkg)) {
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
|
|
rcu_read_lock();
|
|
spin_lock_irq(&q->queue_lock);
|
|
|
|
blkg = blkg_lookup_check(pos, pol, q);
|
|
if (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
goto fail_unlock;
|
|
}
|
|
|
|
if (blkg) {
|
|
blkg_free(new_blkg);
|
|
} else {
|
|
blkg = blkg_create(pos, q, new_blkg);
|
|
if (unlikely(IS_ERR(blkg))) {
|
|
ret = PTR_ERR(blkg);
|
|
goto fail_unlock;
|
|
}
|
|
}
|
|
|
|
if (pos == blkcg)
|
|
goto success;
|
|
}
|
|
success:
|
|
ctx->disk = disk;
|
|
ctx->blkg = blkg;
|
|
ctx->body = body;
|
|
return 0;
|
|
|
|
fail_unlock:
|
|
spin_unlock_irq(&q->queue_lock);
|
|
rcu_read_unlock();
|
|
fail:
|
|
put_disk_and_module(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);
|
|
ret = restart_syscall();
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* blkg_conf_finish - finish up per-blkg config update
|
|
* @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
|
|
*
|
|
* Finish up after per-blkg config update. This function must be paired
|
|
* with blkg_conf_prep().
|
|
*/
|
|
void blkg_conf_finish(struct blkg_conf_ctx *ctx)
|
|
__releases(&ctx->disk->queue->queue_lock) __releases(rcu)
|
|
{
|
|
spin_unlock_irq(&ctx->disk->queue->queue_lock);
|
|
rcu_read_unlock();
|
|
put_disk_and_module(ctx->disk);
|
|
}
|
|
|
|
static int blkcg_print_stat(struct seq_file *sf, void *v)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
|
|
struct blkcg_gq *blkg;
|
|
|
|
rcu_read_lock();
|
|
|
|
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
|
|
const char *dname;
|
|
char *buf;
|
|
struct blkg_rwstat rwstat;
|
|
u64 rbytes, wbytes, rios, wios, dbytes, dios;
|
|
size_t size = seq_get_buf(sf, &buf), off = 0;
|
|
int i;
|
|
bool has_stats = false;
|
|
|
|
dname = blkg_dev_name(blkg);
|
|
if (!dname)
|
|
continue;
|
|
|
|
/*
|
|
* Hooray string manipulation, count is the size written NOT
|
|
* INCLUDING THE \0, so size is now count+1 less than what we
|
|
* had before, but we want to start writing the next bit from
|
|
* the \0 so we only add count to buf.
|
|
*/
|
|
off += scnprintf(buf+off, size-off, "%s ", dname);
|
|
|
|
spin_lock_irq(&blkg->q->queue_lock);
|
|
|
|
rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
|
|
offsetof(struct blkcg_gq, stat_bytes));
|
|
rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
|
|
wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
|
|
dbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]);
|
|
|
|
rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
|
|
offsetof(struct blkcg_gq, stat_ios));
|
|
rios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
|
|
wios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
|
|
dios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]);
|
|
|
|
spin_unlock_irq(&blkg->q->queue_lock);
|
|
|
|
if (rbytes || wbytes || rios || wios) {
|
|
has_stats = true;
|
|
off += scnprintf(buf+off, size-off,
|
|
"rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu",
|
|
rbytes, wbytes, rios, wios,
|
|
dbytes, dios);
|
|
}
|
|
|
|
if (!blkcg_debug_stats)
|
|
goto next;
|
|
|
|
if (atomic_read(&blkg->use_delay)) {
|
|
has_stats = true;
|
|
off += scnprintf(buf+off, size-off,
|
|
" use_delay=%d delay_nsec=%llu",
|
|
atomic_read(&blkg->use_delay),
|
|
(unsigned long long)atomic64_read(&blkg->delay_nsec));
|
|
}
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
size_t written;
|
|
|
|
if (!blkg->pd[i] || !pol->pd_stat_fn)
|
|
continue;
|
|
|
|
written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off);
|
|
if (written)
|
|
has_stats = true;
|
|
off += written;
|
|
}
|
|
next:
|
|
if (has_stats) {
|
|
off += scnprintf(buf+off, size-off, "\n");
|
|
seq_commit(sf, off);
|
|
}
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
return 0;
|
|
}
|
|
|
|
static struct cftype blkcg_files[] = {
|
|
{
|
|
.name = "stat",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.seq_show = blkcg_print_stat,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
static struct cftype blkcg_legacy_files[] = {
|
|
{
|
|
.name = "reset_stats",
|
|
.write_u64 = blkcg_reset_stats,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/*
|
|
* blkcg destruction is a three-stage process.
|
|
*
|
|
* 1. Destruction starts. The blkcg_css_offline() callback is invoked
|
|
* which offlines writeback. Here we tie the next stage of blkg destruction
|
|
* to the completion of writeback associated with the blkcg. This lets us
|
|
* avoid punting potentially large amounts of outstanding writeback to root
|
|
* while maintaining any ongoing policies. The next stage is triggered when
|
|
* the nr_cgwbs count goes to zero.
|
|
*
|
|
* 2. When the nr_cgwbs count goes to zero, blkcg_destroy_blkgs() is called
|
|
* and handles the destruction of blkgs. Here the css reference held by
|
|
* the blkg is put back eventually allowing blkcg_css_free() to be called.
|
|
* This work may occur in cgwb_release_workfn() on the cgwb_release
|
|
* workqueue. Any submitted ios that fail to get the blkg ref will be
|
|
* punted to the root_blkg.
|
|
*
|
|
* 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called.
|
|
* This finally frees the blkcg.
|
|
*/
|
|
|
|
/**
|
|
* blkcg_css_offline - cgroup css_offline callback
|
|
* @css: css of interest
|
|
*
|
|
* This function is called when @css is about to go away. Here the cgwbs are
|
|
* offlined first and only once writeback associated with the blkcg has
|
|
* finished do we start step 2 (see above).
|
|
*/
|
|
static void blkcg_css_offline(struct cgroup_subsys_state *css)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(css);
|
|
|
|
/* this prevents anyone from attaching or migrating to this blkcg */
|
|
wb_blkcg_offline(blkcg);
|
|
|
|
/* put the base cgwb reference allowing step 2 to be triggered */
|
|
blkcg_cgwb_put(blkcg);
|
|
}
|
|
|
|
/**
|
|
* blkcg_destroy_blkgs - responsible for shooting down blkgs
|
|
* @blkcg: blkcg of interest
|
|
*
|
|
* 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.
|
|
* Destroying the blkgs releases the reference held on the blkcg's css allowing
|
|
* blkcg_css_free to eventually be called.
|
|
*
|
|
* This is the blkcg counterpart of ioc_release_fn().
|
|
*/
|
|
void blkcg_destroy_blkgs(struct blkcg *blkcg)
|
|
{
|
|
spin_lock_irq(&blkcg->lock);
|
|
|
|
while (!hlist_empty(&blkcg->blkg_list)) {
|
|
struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
|
|
struct blkcg_gq, 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);
|
|
}
|
|
|
|
static void blkcg_css_free(struct cgroup_subsys_state *css)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(css);
|
|
int i;
|
|
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
list_del(&blkcg->all_blkcgs_node);
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++)
|
|
if (blkcg->cpd[i])
|
|
blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
|
|
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
|
|
kfree(blkcg);
|
|
}
|
|
|
|
static struct cgroup_subsys_state *
|
|
blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
|
|
{
|
|
struct blkcg *blkcg;
|
|
struct cgroup_subsys_state *ret;
|
|
int i;
|
|
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
if (!parent_css) {
|
|
blkcg = &blkcg_root;
|
|
} else {
|
|
blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
|
|
if (!blkcg) {
|
|
ret = ERR_PTR(-ENOMEM);
|
|
goto unlock;
|
|
}
|
|
}
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS ; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
struct blkcg_policy_data *cpd;
|
|
|
|
/*
|
|
* If the policy hasn't been attached yet, wait for it
|
|
* to be attached before doing anything else. Otherwise,
|
|
* check if the policy requires any specific per-cgroup
|
|
* data: if it does, allocate and initialize it.
|
|
*/
|
|
if (!pol || !pol->cpd_alloc_fn)
|
|
continue;
|
|
|
|
cpd = pol->cpd_alloc_fn(GFP_KERNEL);
|
|
if (!cpd) {
|
|
ret = ERR_PTR(-ENOMEM);
|
|
goto free_pd_blkcg;
|
|
}
|
|
blkcg->cpd[i] = cpd;
|
|
cpd->blkcg = blkcg;
|
|
cpd->plid = i;
|
|
if (pol->cpd_init_fn)
|
|
pol->cpd_init_fn(cpd);
|
|
}
|
|
|
|
spin_lock_init(&blkcg->lock);
|
|
INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN);
|
|
INIT_HLIST_HEAD(&blkcg->blkg_list);
|
|
#ifdef CONFIG_CGROUP_WRITEBACK
|
|
INIT_LIST_HEAD(&blkcg->cgwb_list);
|
|
refcount_set(&blkcg->cgwb_refcnt, 1);
|
|
#endif
|
|
list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs);
|
|
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
return &blkcg->css;
|
|
|
|
free_pd_blkcg:
|
|
for (i--; i >= 0; i--)
|
|
if (blkcg->cpd[i])
|
|
blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
|
|
|
|
if (blkcg != &blkcg_root)
|
|
kfree(blkcg);
|
|
unlock:
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
struct blkcg_gq *new_blkg, *blkg;
|
|
bool preloaded;
|
|
int ret;
|
|
|
|
new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);
|
|
if (!new_blkg)
|
|
return -ENOMEM;
|
|
|
|
preloaded = !radix_tree_preload(GFP_KERNEL);
|
|
|
|
/* Make sure the root blkg exists. */
|
|
rcu_read_lock();
|
|
spin_lock_irq(&q->queue_lock);
|
|
blkg = blkg_create(&blkcg_root, q, new_blkg);
|
|
if (IS_ERR(blkg))
|
|
goto err_unlock;
|
|
q->root_blkg = blkg;
|
|
spin_unlock_irq(&q->queue_lock);
|
|
rcu_read_unlock();
|
|
|
|
if (preloaded)
|
|
radix_tree_preload_end();
|
|
|
|
ret = blk_iolatency_init(q);
|
|
if (ret)
|
|
goto err_destroy_all;
|
|
|
|
ret = blk_throtl_init(q);
|
|
if (ret)
|
|
goto err_destroy_all;
|
|
return 0;
|
|
|
|
err_destroy_all:
|
|
blkg_destroy_all(q);
|
|
return ret;
|
|
err_unlock:
|
|
spin_unlock_irq(&q->queue_lock);
|
|
rcu_read_unlock();
|
|
if (preloaded)
|
|
radix_tree_preload_end();
|
|
return PTR_ERR(blkg);
|
|
}
|
|
|
|
/**
|
|
* 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);
|
|
|
|
/*
|
|
* @q could be exiting and already have destroyed all blkgs as
|
|
* indicated by NULL root_blkg. If so, don't confuse policies.
|
|
*/
|
|
if (!q->root_blkg)
|
|
return;
|
|
|
|
blk_throtl_drain(q);
|
|
}
|
|
|
|
/**
|
|
* blkcg_exit_queue - exit and release blkcg part of request_queue
|
|
* @q: request_queue being released
|
|
*
|
|
* Called from blk_exit_queue(). Responsible for exiting blkcg part.
|
|
*/
|
|
void blkcg_exit_queue(struct request_queue *q)
|
|
{
|
|
blkg_destroy_all(q);
|
|
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 blkcg_can_attach(struct cgroup_taskset *tset)
|
|
{
|
|
struct task_struct *task;
|
|
struct cgroup_subsys_state *dst_css;
|
|
struct io_context *ioc;
|
|
int ret = 0;
|
|
|
|
/* task_lock() is needed to avoid races with exit_io_context() */
|
|
cgroup_taskset_for_each(task, dst_css, 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_bind(struct cgroup_subsys_state *root_css)
|
|
{
|
|
int i;
|
|
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
struct blkcg *blkcg;
|
|
|
|
if (!pol || !pol->cpd_bind_fn)
|
|
continue;
|
|
|
|
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node)
|
|
if (blkcg->cpd[pol->plid])
|
|
pol->cpd_bind_fn(blkcg->cpd[pol->plid]);
|
|
}
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
}
|
|
|
|
static void blkcg_exit(struct task_struct *tsk)
|
|
{
|
|
if (tsk->throttle_queue)
|
|
blk_put_queue(tsk->throttle_queue);
|
|
tsk->throttle_queue = NULL;
|
|
}
|
|
|
|
struct cgroup_subsys io_cgrp_subsys = {
|
|
.css_alloc = blkcg_css_alloc,
|
|
.css_offline = blkcg_css_offline,
|
|
.css_free = blkcg_css_free,
|
|
.can_attach = blkcg_can_attach,
|
|
.bind = blkcg_bind,
|
|
.dfl_cftypes = blkcg_files,
|
|
.legacy_cftypes = blkcg_legacy_files,
|
|
.legacy_name = "blkio",
|
|
.exit = blkcg_exit,
|
|
#ifdef CONFIG_MEMCG
|
|
/*
|
|
* This ensures that, if available, memcg is automatically enabled
|
|
* together on the default hierarchy so that the owner cgroup can
|
|
* be retrieved from writeback pages.
|
|
*/
|
|
.depends_on = 1 << memory_cgrp_id,
|
|
#endif
|
|
};
|
|
EXPORT_SYMBOL_GPL(io_cgrp_subsys);
|
|
|
|
/**
|
|
* blkcg_activate_policy - activate a blkcg policy on a request_queue
|
|
* @q: request_queue of interest
|
|
* @pol: blkcg policy to activate
|
|
*
|
|
* Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through
|
|
* bypass mode to populate its blkgs with policy_data for @pol.
|
|
*
|
|
* Activation happens with @q bypassed, so nobody would be accessing blkgs
|
|
* from IO path. Update of each blkg is protected by both queue and blkcg
|
|
* locks so that holding either lock and testing blkcg_policy_enabled() is
|
|
* always enough for dereferencing policy data.
|
|
*
|
|
* The caller is responsible for synchronizing [de]activations and policy
|
|
* [un]registerations. Returns 0 on success, -errno on failure.
|
|
*/
|
|
int blkcg_activate_policy(struct request_queue *q,
|
|
const struct blkcg_policy *pol)
|
|
{
|
|
struct blkg_policy_data *pd_prealloc = NULL;
|
|
struct blkcg_gq *blkg;
|
|
int ret;
|
|
|
|
if (blkcg_policy_enabled(q, pol))
|
|
return 0;
|
|
|
|
if (queue_is_mq(q))
|
|
blk_mq_freeze_queue(q);
|
|
pd_prealloc:
|
|
if (!pd_prealloc) {
|
|
pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q->node);
|
|
if (!pd_prealloc) {
|
|
ret = -ENOMEM;
|
|
goto out_bypass_end;
|
|
}
|
|
}
|
|
|
|
spin_lock_irq(&q->queue_lock);
|
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node) {
|
|
struct blkg_policy_data *pd;
|
|
|
|
if (blkg->pd[pol->plid])
|
|
continue;
|
|
|
|
pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q->node);
|
|
if (!pd)
|
|
swap(pd, pd_prealloc);
|
|
if (!pd) {
|
|
spin_unlock_irq(&q->queue_lock);
|
|
goto pd_prealloc;
|
|
}
|
|
|
|
blkg->pd[pol->plid] = pd;
|
|
pd->blkg = blkg;
|
|
pd->plid = pol->plid;
|
|
if (pol->pd_init_fn)
|
|
pol->pd_init_fn(pd);
|
|
}
|
|
|
|
__set_bit(pol->plid, q->blkcg_pols);
|
|
ret = 0;
|
|
|
|
spin_unlock_irq(&q->queue_lock);
|
|
out_bypass_end:
|
|
if (queue_is_mq(q))
|
|
blk_mq_unfreeze_queue(q);
|
|
if (pd_prealloc)
|
|
pol->pd_free_fn(pd_prealloc);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_activate_policy);
|
|
|
|
/**
|
|
* blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue
|
|
* @q: request_queue of interest
|
|
* @pol: blkcg policy to deactivate
|
|
*
|
|
* Deactivate @pol on @q. Follows the same synchronization rules as
|
|
* blkcg_activate_policy().
|
|
*/
|
|
void blkcg_deactivate_policy(struct request_queue *q,
|
|
const struct blkcg_policy *pol)
|
|
{
|
|
struct blkcg_gq *blkg;
|
|
|
|
if (!blkcg_policy_enabled(q, pol))
|
|
return;
|
|
|
|
if (queue_is_mq(q))
|
|
blk_mq_freeze_queue(q);
|
|
|
|
spin_lock_irq(&q->queue_lock);
|
|
|
|
__clear_bit(pol->plid, q->blkcg_pols);
|
|
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node) {
|
|
if (blkg->pd[pol->plid]) {
|
|
if (pol->pd_offline_fn)
|
|
pol->pd_offline_fn(blkg->pd[pol->plid]);
|
|
pol->pd_free_fn(blkg->pd[pol->plid]);
|
|
blkg->pd[pol->plid] = NULL;
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(&q->queue_lock);
|
|
|
|
if (queue_is_mq(q))
|
|
blk_mq_unfreeze_queue(q);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
|
|
|
|
/**
|
|
* blkcg_policy_register - register a blkcg policy
|
|
* @pol: blkcg policy to register
|
|
*
|
|
* Register @pol with blkcg core. Might sleep and @pol may be modified on
|
|
* successful registration. Returns 0 on success and -errno on failure.
|
|
*/
|
|
int blkcg_policy_register(struct blkcg_policy *pol)
|
|
{
|
|
struct blkcg *blkcg;
|
|
int i, ret;
|
|
|
|
mutex_lock(&blkcg_pol_register_mutex);
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
/* find an empty slot */
|
|
ret = -ENOSPC;
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++)
|
|
if (!blkcg_policy[i])
|
|
break;
|
|
if (i >= BLKCG_MAX_POLS) {
|
|
pr_warn("blkcg_policy_register: BLKCG_MAX_POLS too small\n");
|
|
goto err_unlock;
|
|
}
|
|
|
|
/* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */
|
|
if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) ||
|
|
(!pol->pd_alloc_fn ^ !pol->pd_free_fn))
|
|
goto err_unlock;
|
|
|
|
/* register @pol */
|
|
pol->plid = i;
|
|
blkcg_policy[pol->plid] = pol;
|
|
|
|
/* allocate and install cpd's */
|
|
if (pol->cpd_alloc_fn) {
|
|
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
|
|
struct blkcg_policy_data *cpd;
|
|
|
|
cpd = pol->cpd_alloc_fn(GFP_KERNEL);
|
|
if (!cpd)
|
|
goto err_free_cpds;
|
|
|
|
blkcg->cpd[pol->plid] = cpd;
|
|
cpd->blkcg = blkcg;
|
|
cpd->plid = pol->plid;
|
|
pol->cpd_init_fn(cpd);
|
|
}
|
|
}
|
|
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
|
|
/* everything is in place, add intf files for the new policy */
|
|
if (pol->dfl_cftypes)
|
|
WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys,
|
|
pol->dfl_cftypes));
|
|
if (pol->legacy_cftypes)
|
|
WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys,
|
|
pol->legacy_cftypes));
|
|
mutex_unlock(&blkcg_pol_register_mutex);
|
|
return 0;
|
|
|
|
err_free_cpds:
|
|
if (pol->cpd_free_fn) {
|
|
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
|
|
if (blkcg->cpd[pol->plid]) {
|
|
pol->cpd_free_fn(blkcg->cpd[pol->plid]);
|
|
blkcg->cpd[pol->plid] = NULL;
|
|
}
|
|
}
|
|
}
|
|
blkcg_policy[pol->plid] = NULL;
|
|
err_unlock:
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
mutex_unlock(&blkcg_pol_register_mutex);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_policy_register);
|
|
|
|
/**
|
|
* blkcg_policy_unregister - unregister a blkcg policy
|
|
* @pol: blkcg policy to unregister
|
|
*
|
|
* Undo blkcg_policy_register(@pol). Might sleep.
|
|
*/
|
|
void blkcg_policy_unregister(struct blkcg_policy *pol)
|
|
{
|
|
struct blkcg *blkcg;
|
|
|
|
mutex_lock(&blkcg_pol_register_mutex);
|
|
|
|
if (WARN_ON(blkcg_policy[pol->plid] != pol))
|
|
goto out_unlock;
|
|
|
|
/* kill the intf files first */
|
|
if (pol->dfl_cftypes)
|
|
cgroup_rm_cftypes(pol->dfl_cftypes);
|
|
if (pol->legacy_cftypes)
|
|
cgroup_rm_cftypes(pol->legacy_cftypes);
|
|
|
|
/* remove cpds and unregister */
|
|
mutex_lock(&blkcg_pol_mutex);
|
|
|
|
if (pol->cpd_free_fn) {
|
|
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
|
|
if (blkcg->cpd[pol->plid]) {
|
|
pol->cpd_free_fn(blkcg->cpd[pol->plid]);
|
|
blkcg->cpd[pol->plid] = NULL;
|
|
}
|
|
}
|
|
}
|
|
blkcg_policy[pol->plid] = NULL;
|
|
|
|
mutex_unlock(&blkcg_pol_mutex);
|
|
out_unlock:
|
|
mutex_unlock(&blkcg_pol_register_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkcg_policy_unregister);
|
|
|
|
/*
|
|
* Scale the accumulated delay based on how long it has been since we updated
|
|
* the delay. We only call this when we are adding delay, in case it's been a
|
|
* while since we added delay, and when we are checking to see if we need to
|
|
* delay a task, to account for any delays that may have occurred.
|
|
*/
|
|
static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now)
|
|
{
|
|
u64 old = atomic64_read(&blkg->delay_start);
|
|
|
|
/*
|
|
* We only want to scale down every second. The idea here is that we
|
|
* want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain
|
|
* time window. We only want to throttle tasks for recent delay that
|
|
* has occurred, in 1 second time windows since that's the maximum
|
|
* things can be throttled. We save the current delay window in
|
|
* blkg->last_delay so we know what amount is still left to be charged
|
|
* to the blkg from this point onward. blkg->last_use keeps track of
|
|
* the use_delay counter. The idea is if we're unthrottling the blkg we
|
|
* are ok with whatever is happening now, and we can take away more of
|
|
* the accumulated delay as we've already throttled enough that
|
|
* everybody is happy with their IO latencies.
|
|
*/
|
|
if (time_before64(old + NSEC_PER_SEC, now) &&
|
|
atomic64_cmpxchg(&blkg->delay_start, old, now) == old) {
|
|
u64 cur = atomic64_read(&blkg->delay_nsec);
|
|
u64 sub = min_t(u64, blkg->last_delay, now - old);
|
|
int cur_use = atomic_read(&blkg->use_delay);
|
|
|
|
/*
|
|
* We've been unthrottled, subtract a larger chunk of our
|
|
* accumulated delay.
|
|
*/
|
|
if (cur_use < blkg->last_use)
|
|
sub = max_t(u64, sub, blkg->last_delay >> 1);
|
|
|
|
/*
|
|
* This shouldn't happen, but handle it anyway. Our delay_nsec
|
|
* should only ever be growing except here where we subtract out
|
|
* min(last_delay, 1 second), but lord knows bugs happen and I'd
|
|
* rather not end up with negative numbers.
|
|
*/
|
|
if (unlikely(cur < sub)) {
|
|
atomic64_set(&blkg->delay_nsec, 0);
|
|
blkg->last_delay = 0;
|
|
} else {
|
|
atomic64_sub(sub, &blkg->delay_nsec);
|
|
blkg->last_delay = cur - sub;
|
|
}
|
|
blkg->last_use = cur_use;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This is called when we want to actually walk up the hierarchy and check to
|
|
* see if we need to throttle, and then actually throttle if there is some
|
|
* accumulated delay. This should only be called upon return to user space so
|
|
* we're not holding some lock that would induce a priority inversion.
|
|
*/
|
|
static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay)
|
|
{
|
|
u64 now = ktime_to_ns(ktime_get());
|
|
u64 exp;
|
|
u64 delay_nsec = 0;
|
|
int tok;
|
|
|
|
while (blkg->parent) {
|
|
if (atomic_read(&blkg->use_delay)) {
|
|
blkcg_scale_delay(blkg, now);
|
|
delay_nsec = max_t(u64, delay_nsec,
|
|
atomic64_read(&blkg->delay_nsec));
|
|
}
|
|
blkg = blkg->parent;
|
|
}
|
|
|
|
if (!delay_nsec)
|
|
return;
|
|
|
|
/*
|
|
* Let's not sleep for all eternity if we've amassed a huge delay.
|
|
* Swapping or metadata IO can accumulate 10's of seconds worth of
|
|
* delay, and we want userspace to be able to do _something_ so cap the
|
|
* delays at 1 second. If there's 10's of seconds worth of delay then
|
|
* the tasks will be delayed for 1 second for every syscall.
|
|
*/
|
|
delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC);
|
|
|
|
/*
|
|
* TODO: the use_memdelay flag is going to be for the upcoming psi stuff
|
|
* that hasn't landed upstream yet. Once that stuff is in place we need
|
|
* to do a psi_memstall_enter/leave if memdelay is set.
|
|
*/
|
|
|
|
exp = ktime_add_ns(now, delay_nsec);
|
|
tok = io_schedule_prepare();
|
|
do {
|
|
__set_current_state(TASK_KILLABLE);
|
|
if (!schedule_hrtimeout(&exp, HRTIMER_MODE_ABS))
|
|
break;
|
|
} while (!fatal_signal_pending(current));
|
|
io_schedule_finish(tok);
|
|
}
|
|
|
|
/**
|
|
* blkcg_maybe_throttle_current - throttle the current task if it has been marked
|
|
*
|
|
* This is only called if we've been marked with set_notify_resume(). Obviously
|
|
* we can be set_notify_resume() for reasons other than blkcg throttling, so we
|
|
* check to see if current->throttle_queue is set and if not this doesn't do
|
|
* anything. This should only ever be called by the resume code, it's not meant
|
|
* to be called by people willy-nilly as it will actually do the work to
|
|
* throttle the task if it is setup for throttling.
|
|
*/
|
|
void blkcg_maybe_throttle_current(void)
|
|
{
|
|
struct request_queue *q = current->throttle_queue;
|
|
struct cgroup_subsys_state *css;
|
|
struct blkcg *blkcg;
|
|
struct blkcg_gq *blkg;
|
|
bool use_memdelay = current->use_memdelay;
|
|
|
|
if (!q)
|
|
return;
|
|
|
|
current->throttle_queue = NULL;
|
|
current->use_memdelay = false;
|
|
|
|
rcu_read_lock();
|
|
css = kthread_blkcg();
|
|
if (css)
|
|
blkcg = css_to_blkcg(css);
|
|
else
|
|
blkcg = css_to_blkcg(task_css(current, io_cgrp_id));
|
|
|
|
if (!blkcg)
|
|
goto out;
|
|
blkg = blkg_lookup(blkcg, q);
|
|
if (!blkg)
|
|
goto out;
|
|
if (!blkg_tryget(blkg))
|
|
goto out;
|
|
rcu_read_unlock();
|
|
|
|
blkcg_maybe_throttle_blkg(blkg, use_memdelay);
|
|
blkg_put(blkg);
|
|
blk_put_queue(q);
|
|
return;
|
|
out:
|
|
rcu_read_unlock();
|
|
blk_put_queue(q);
|
|
}
|
|
|
|
/**
|
|
* blkcg_schedule_throttle - this task needs to check for throttling
|
|
* @q - the request queue IO was submitted on
|
|
* @use_memdelay - do we charge this to memory delay for PSI
|
|
*
|
|
* This is called by the IO controller when we know there's delay accumulated
|
|
* for the blkg for this task. We do not pass the blkg because there are places
|
|
* we call this that may not have that information, the swapping code for
|
|
* instance will only have a request_queue at that point. This set's the
|
|
* notify_resume for the task to check and see if it requires throttling before
|
|
* returning to user space.
|
|
*
|
|
* We will only schedule once per syscall. You can call this over and over
|
|
* again and it will only do the check once upon return to user space, and only
|
|
* throttle once. If the task needs to be throttled again it'll need to be
|
|
* re-set at the next time we see the task.
|
|
*/
|
|
void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay)
|
|
{
|
|
if (unlikely(current->flags & PF_KTHREAD))
|
|
return;
|
|
|
|
if (!blk_get_queue(q))
|
|
return;
|
|
|
|
if (current->throttle_queue)
|
|
blk_put_queue(current->throttle_queue);
|
|
current->throttle_queue = q;
|
|
if (use_memdelay)
|
|
current->use_memdelay = use_memdelay;
|
|
set_notify_resume(current);
|
|
}
|
|
|
|
/**
|
|
* blkcg_add_delay - add delay to this blkg
|
|
* @now - the current time in nanoseconds
|
|
* @delta - how many nanoseconds of delay to add
|
|
*
|
|
* Charge @delta to the blkg's current delay accumulation. This is used to
|
|
* throttle tasks if an IO controller thinks we need more throttling.
|
|
*/
|
|
void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta)
|
|
{
|
|
blkcg_scale_delay(blkg, now);
|
|
atomic64_add(delta, &blkg->delay_nsec);
|
|
}
|
|
|
|
module_param(blkcg_debug_stats, bool, 0644);
|
|
MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not");
|