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1305e2c9d9
A previous commit got rid of unnecessary rcu_read_lock() inside the
IRQ disabling queue_lock, but this debug statement was left. It's now
firing since we are indeed not inside a RCU read lock, but we don't
need to be as we're still preempt safe.
Get rid of the check, as we have a lockdep assert for holding the
queue lock right after it anyway.
Link: https://lore.kernel.org/linux-block/46253c48-81cb-0787-20ad-9133afdd9e21@samsung.com/
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: 77c570a1ea
("blk-cgroup: Remove unnecessary rcu_read_lock/unlock()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2050 lines
53 KiB
C
2050 lines
53 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Common Block IO controller cgroup interface
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*
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* Based on ideas and code from CFQ, CFS and BFQ:
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* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
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*
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* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
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* Paolo Valente <paolo.valente@unimore.it>
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*
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* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
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* Nauman Rafique <nauman@google.com>
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*
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* For policy-specific per-blkcg data:
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* Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
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* Arianna Avanzini <avanzini.arianna@gmail.com>
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*/
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#include <linux/ioprio.h>
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#include <linux/kdev_t.h>
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#include <linux/module.h>
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#include <linux/sched/signal.h>
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#include <linux/err.h>
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#include <linux/blkdev.h>
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#include <linux/backing-dev.h>
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#include <linux/slab.h>
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#include <linux/delay.h>
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#include <linux/atomic.h>
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#include <linux/ctype.h>
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#include <linux/resume_user_mode.h>
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#include <linux/psi.h>
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#include <linux/part_stat.h>
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#include "blk.h"
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#include "blk-cgroup.h"
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#include "blk-ioprio.h"
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#include "blk-throttle.h"
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/*
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* blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation.
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* blkcg_pol_register_mutex nests outside of it and synchronizes entire
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* policy [un]register operations including cgroup file additions /
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* removals. Putting cgroup file registration outside blkcg_pol_mutex
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* allows grabbing it from cgroup callbacks.
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*/
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static DEFINE_MUTEX(blkcg_pol_register_mutex);
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static DEFINE_MUTEX(blkcg_pol_mutex);
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struct blkcg blkcg_root;
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EXPORT_SYMBOL_GPL(blkcg_root);
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struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css;
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EXPORT_SYMBOL_GPL(blkcg_root_css);
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static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
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static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */
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bool blkcg_debug_stats = false;
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static struct workqueue_struct *blkcg_punt_bio_wq;
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#define BLKG_DESTROY_BATCH_SIZE 64
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/**
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* blkcg_css - find the current css
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*
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* Find the css associated with either the kthread or the current task.
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* This may return a dying css, so it is up to the caller to use tryget logic
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* to confirm it is alive and well.
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*/
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static struct cgroup_subsys_state *blkcg_css(void)
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{
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struct cgroup_subsys_state *css;
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css = kthread_blkcg();
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if (css)
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return css;
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return task_css(current, io_cgrp_id);
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}
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static bool blkcg_policy_enabled(struct request_queue *q,
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const struct blkcg_policy *pol)
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{
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return pol && test_bit(pol->plid, q->blkcg_pols);
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}
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static void blkg_free_workfn(struct work_struct *work)
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{
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struct blkcg_gq *blkg = container_of(work, struct blkcg_gq,
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free_work);
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int i;
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for (i = 0; i < BLKCG_MAX_POLS; i++)
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if (blkg->pd[i])
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blkcg_policy[i]->pd_free_fn(blkg->pd[i]);
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if (blkg->q)
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blk_put_queue(blkg->q);
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free_percpu(blkg->iostat_cpu);
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percpu_ref_exit(&blkg->refcnt);
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kfree(blkg);
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}
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/**
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* blkg_free - free a blkg
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* @blkg: blkg to free
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*
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* Free @blkg which may be partially allocated.
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*/
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static void blkg_free(struct blkcg_gq *blkg)
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{
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if (!blkg)
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return;
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/*
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* Both ->pd_free_fn() and request queue's release handler may
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* sleep, so free us by scheduling one work func
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*/
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INIT_WORK(&blkg->free_work, blkg_free_workfn);
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schedule_work(&blkg->free_work);
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}
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static void __blkg_release(struct rcu_head *rcu)
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{
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struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head);
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WARN_ON(!bio_list_empty(&blkg->async_bios));
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/* release the blkcg and parent blkg refs this blkg has been holding */
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css_put(&blkg->blkcg->css);
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if (blkg->parent)
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blkg_put(blkg->parent);
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blkg_free(blkg);
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}
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/*
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* A group is RCU protected, but having an rcu lock does not mean that one
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* can access all the fields of blkg and assume these are valid. For
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* example, don't try to follow throtl_data and request queue links.
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*
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* Having a reference to blkg under an rcu allows accesses to only values
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* local to groups like group stats and group rate limits.
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*/
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static void blkg_release(struct percpu_ref *ref)
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{
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struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt);
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call_rcu(&blkg->rcu_head, __blkg_release);
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}
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static void blkg_async_bio_workfn(struct work_struct *work)
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{
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struct blkcg_gq *blkg = container_of(work, struct blkcg_gq,
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async_bio_work);
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struct bio_list bios = BIO_EMPTY_LIST;
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struct bio *bio;
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struct blk_plug plug;
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bool need_plug = false;
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/* as long as there are pending bios, @blkg can't go away */
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spin_lock_bh(&blkg->async_bio_lock);
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bio_list_merge(&bios, &blkg->async_bios);
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bio_list_init(&blkg->async_bios);
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spin_unlock_bh(&blkg->async_bio_lock);
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/* start plug only when bio_list contains at least 2 bios */
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if (bios.head && bios.head->bi_next) {
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need_plug = true;
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blk_start_plug(&plug);
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}
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while ((bio = bio_list_pop(&bios)))
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submit_bio(bio);
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if (need_plug)
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blk_finish_plug(&plug);
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}
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/**
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* bio_blkcg_css - return the blkcg CSS associated with a bio
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* @bio: target bio
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*
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* This returns the CSS for the blkcg associated with a bio, or %NULL if not
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* associated. Callers are expected to either handle %NULL or know association
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* has been done prior to calling this.
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*/
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struct cgroup_subsys_state *bio_blkcg_css(struct bio *bio)
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{
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if (!bio || !bio->bi_blkg)
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return NULL;
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return &bio->bi_blkg->blkcg->css;
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}
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EXPORT_SYMBOL_GPL(bio_blkcg_css);
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/**
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* blkcg_parent - get the parent of a blkcg
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* @blkcg: blkcg of interest
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*
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* Return the parent blkcg of @blkcg. Can be called anytime.
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*/
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static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
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{
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return css_to_blkcg(blkcg->css.parent);
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}
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/**
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* blkg_alloc - allocate a blkg
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* @blkcg: block cgroup the new blkg is associated with
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* @q: request_queue the new blkg is associated with
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* @gfp_mask: allocation mask to use
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*
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* Allocate a new blkg assocating @blkcg and @q.
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*/
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static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
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gfp_t gfp_mask)
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{
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struct blkcg_gq *blkg;
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int i, cpu;
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/* alloc and init base part */
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blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node);
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if (!blkg)
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return NULL;
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if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask))
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goto err_free;
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blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask);
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if (!blkg->iostat_cpu)
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goto err_free;
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if (!blk_get_queue(q))
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goto err_free;
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blkg->q = q;
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INIT_LIST_HEAD(&blkg->q_node);
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spin_lock_init(&blkg->async_bio_lock);
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bio_list_init(&blkg->async_bios);
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INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn);
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blkg->blkcg = blkcg;
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u64_stats_init(&blkg->iostat.sync);
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for_each_possible_cpu(cpu)
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u64_stats_init(&per_cpu_ptr(blkg->iostat_cpu, cpu)->sync);
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkcg_policy *pol = blkcg_policy[i];
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struct blkg_policy_data *pd;
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if (!blkcg_policy_enabled(q, pol))
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continue;
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/* alloc per-policy data and attach it to blkg */
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pd = pol->pd_alloc_fn(gfp_mask, q, blkcg);
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if (!pd)
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goto err_free;
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blkg->pd[i] = pd;
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pd->blkg = blkg;
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pd->plid = i;
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}
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return blkg;
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err_free:
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blkg_free(blkg);
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return NULL;
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}
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struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
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struct request_queue *q, bool update_hint)
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{
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struct blkcg_gq *blkg;
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/*
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* Hint didn't match. Look up from the radix tree. Note that the
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* hint can only be updated under queue_lock as otherwise @blkg
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* could have already been removed from blkg_tree. The caller is
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* responsible for grabbing queue_lock if @update_hint.
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*/
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blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
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if (blkg && blkg->q == q) {
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if (update_hint) {
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lockdep_assert_held(&q->queue_lock);
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rcu_assign_pointer(blkcg->blkg_hint, blkg);
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}
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return blkg;
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}
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return NULL;
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}
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EXPORT_SYMBOL_GPL(blkg_lookup_slowpath);
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/*
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* If @new_blkg is %NULL, this function tries to allocate a new one as
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* necessary using %GFP_NOWAIT. @new_blkg is always consumed on return.
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*/
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static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
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struct request_queue *q,
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struct blkcg_gq *new_blkg)
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{
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struct blkcg_gq *blkg;
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int i, ret;
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lockdep_assert_held(&q->queue_lock);
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/* request_queue is dying, do not create/recreate a blkg */
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if (blk_queue_dying(q)) {
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ret = -ENODEV;
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goto err_free_blkg;
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}
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/* blkg holds a reference to blkcg */
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if (!css_tryget_online(&blkcg->css)) {
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ret = -ENODEV;
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goto err_free_blkg;
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}
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/* allocate */
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if (!new_blkg) {
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new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN);
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if (unlikely(!new_blkg)) {
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ret = -ENOMEM;
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goto err_put_css;
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}
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}
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blkg = new_blkg;
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/* link parent */
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if (blkcg_parent(blkcg)) {
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blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
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if (WARN_ON_ONCE(!blkg->parent)) {
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ret = -ENODEV;
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goto err_put_css;
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}
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blkg_get(blkg->parent);
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}
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/* invoke per-policy init */
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkcg_policy *pol = blkcg_policy[i];
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if (blkg->pd[i] && pol->pd_init_fn)
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pol->pd_init_fn(blkg->pd[i]);
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}
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/* insert */
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spin_lock(&blkcg->lock);
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ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
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if (likely(!ret)) {
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hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
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list_add(&blkg->q_node, &q->blkg_list);
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkcg_policy *pol = blkcg_policy[i];
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if (blkg->pd[i] && pol->pd_online_fn)
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pol->pd_online_fn(blkg->pd[i]);
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}
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}
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blkg->online = true;
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spin_unlock(&blkcg->lock);
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if (!ret)
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return blkg;
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/* @blkg failed fully initialized, use the usual release path */
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blkg_put(blkg);
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return ERR_PTR(ret);
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err_put_css:
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css_put(&blkcg->css);
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err_free_blkg:
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blkg_free(new_blkg);
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return ERR_PTR(ret);
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}
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/**
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* blkg_lookup_create - lookup blkg, try to create one if not there
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* @blkcg: blkcg of interest
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* @q: request_queue of interest
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*
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* Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
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* create one. blkg creation is performed recursively from blkcg_root such
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* that all non-root blkg's have access to the parent blkg. This function
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* should be called under RCU read lock and takes @q->queue_lock.
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*
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* Returns the blkg or the closest blkg if blkg_create() fails as it walks
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* down from root.
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*/
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static struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
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struct request_queue *q)
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{
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struct blkcg_gq *blkg;
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unsigned long flags;
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WARN_ON_ONCE(!rcu_read_lock_held());
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blkg = blkg_lookup(blkcg, q);
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if (blkg)
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return blkg;
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spin_lock_irqsave(&q->queue_lock, flags);
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blkg = __blkg_lookup(blkcg, q, true);
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if (blkg)
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goto found;
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/*
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* Create blkgs walking down from blkcg_root to @blkcg, so that all
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* non-root blkgs have access to their parents. Returns the closest
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* blkg to the intended blkg should blkg_create() fail.
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*/
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while (true) {
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struct blkcg *pos = blkcg;
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struct blkcg *parent = blkcg_parent(blkcg);
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struct blkcg_gq *ret_blkg = q->root_blkg;
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while (parent) {
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blkg = __blkg_lookup(parent, q, false);
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if (blkg) {
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/* remember closest blkg */
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ret_blkg = blkg;
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break;
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}
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pos = parent;
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parent = blkcg_parent(parent);
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}
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blkg = blkg_create(pos, q, NULL);
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if (IS_ERR(blkg)) {
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blkg = ret_blkg;
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break;
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}
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if (pos == blkcg)
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break;
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}
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found:
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spin_unlock_irqrestore(&q->queue_lock, flags);
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return blkg;
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}
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static void blkg_destroy(struct blkcg_gq *blkg)
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{
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struct blkcg *blkcg = blkg->blkcg;
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int i;
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lockdep_assert_held(&blkg->q->queue_lock);
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lockdep_assert_held(&blkcg->lock);
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/* Something wrong if we are trying to remove same group twice */
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WARN_ON_ONCE(list_empty(&blkg->q_node));
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WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkcg_policy *pol = blkcg_policy[i];
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if (blkg->pd[i] && pol->pd_offline_fn)
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pol->pd_offline_fn(blkg->pd[i]);
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}
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blkg->online = false;
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radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
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list_del_init(&blkg->q_node);
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hlist_del_init_rcu(&blkg->blkcg_node);
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/*
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* Both setting lookup hint to and clearing it from @blkg are done
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* under queue_lock. If it's not pointing to @blkg now, it never
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* will. Hint assignment itself can race safely.
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*/
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if (rcu_access_pointer(blkcg->blkg_hint) == blkg)
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rcu_assign_pointer(blkcg->blkg_hint, NULL);
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/*
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* Put the reference taken at the time of creation so that when all
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* queues are gone, group can be destroyed.
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*/
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percpu_ref_kill(&blkg->refcnt);
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}
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|
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/**
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* blkg_destroy_all - destroy all blkgs associated with a request_queue
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* @q: request_queue of interest
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*
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* Destroy all blkgs associated with @q.
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*/
|
|
static void blkg_destroy_all(struct request_queue *q)
|
|
{
|
|
struct blkcg_gq *blkg, *n;
|
|
int count = BLKG_DESTROY_BATCH_SIZE;
|
|
|
|
restart:
|
|
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);
|
|
|
|
/*
|
|
* in order to avoid holding the spin lock for too long, release
|
|
* it when a batch of blkgs are destroyed.
|
|
*/
|
|
if (!(--count)) {
|
|
count = BLKG_DESTROY_BATCH_SIZE;
|
|
spin_unlock_irq(&q->queue_lock);
|
|
cond_resched();
|
|
goto restart;
|
|
}
|
|
}
|
|
|
|
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, cpu;
|
|
|
|
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) {
|
|
for_each_possible_cpu(cpu) {
|
|
struct blkg_iostat_set *bis =
|
|
per_cpu_ptr(blkg->iostat_cpu, cpu);
|
|
memset(bis, 0, sizeof(*bis));
|
|
}
|
|
memset(&blkg->iostat, 0, sizeof(blkg->iostat));
|
|
|
|
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)
|
|
{
|
|
if (!blkg->q->disk || !blkg->q->disk->bdi->dev)
|
|
return NULL;
|
|
return bdi_dev_name(blkg->q->disk->bdi);
|
|
}
|
|
|
|
/**
|
|
* 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);
|
|
|
|
/* 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 */);
|
|
}
|
|
|
|
/**
|
|
* blkcg_conf_open_bdev - parse and open bdev for per-blkg config update
|
|
* @inputp: input string pointer
|
|
*
|
|
* Parse the device node prefix part, MAJ:MIN, of per-blkg config update
|
|
* from @input and get and return the matching bdev. *@inputp is
|
|
* updated to point past the device node prefix. Returns an ERR_PTR()
|
|
* value on error.
|
|
*
|
|
* Use this function iff blkg_conf_prep() can't be used for some reason.
|
|
*/
|
|
struct block_device *blkcg_conf_open_bdev(char **inputp)
|
|
{
|
|
char *input = *inputp;
|
|
unsigned int major, minor;
|
|
struct block_device *bdev;
|
|
int key_len;
|
|
|
|
if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
input += key_len;
|
|
if (!isspace(*input))
|
|
return ERR_PTR(-EINVAL);
|
|
input = skip_spaces(input);
|
|
|
|
bdev = blkdev_get_no_open(MKDEV(major, minor));
|
|
if (!bdev)
|
|
return ERR_PTR(-ENODEV);
|
|
if (bdev_is_partition(bdev)) {
|
|
blkdev_put_no_open(bdev);
|
|
return ERR_PTR(-ENODEV);
|
|
}
|
|
|
|
*inputp = input;
|
|
return bdev;
|
|
}
|
|
|
|
/**
|
|
* 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(&bdev->bd_queue->queue_lock)
|
|
{
|
|
struct block_device *bdev;
|
|
struct request_queue *q;
|
|
struct blkcg_gq *blkg;
|
|
int ret;
|
|
|
|
bdev = blkcg_conf_open_bdev(&input);
|
|
if (IS_ERR(bdev))
|
|
return PTR_ERR(bdev);
|
|
|
|
q = bdev_get_queue(bdev);
|
|
|
|
/*
|
|
* blkcg_deactivate_policy() requires queue to be frozen, we can grab
|
|
* q_usage_counter to prevent concurrent with blkcg_deactivate_policy().
|
|
*/
|
|
ret = blk_queue_enter(q, 0);
|
|
if (ret)
|
|
goto fail;
|
|
|
|
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_exit_queue;
|
|
}
|
|
|
|
if (radix_tree_preload(GFP_KERNEL)) {
|
|
blkg_free(new_blkg);
|
|
ret = -ENOMEM;
|
|
goto fail_exit_queue;
|
|
}
|
|
|
|
rcu_read_lock();
|
|
spin_lock_irq(&q->queue_lock);
|
|
|
|
blkg = blkg_lookup_check(pos, pol, q);
|
|
if (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
blkg_free(new_blkg);
|
|
goto fail_preloaded;
|
|
}
|
|
|
|
if (blkg) {
|
|
blkg_free(new_blkg);
|
|
} else {
|
|
blkg = blkg_create(pos, q, new_blkg);
|
|
if (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
goto fail_preloaded;
|
|
}
|
|
}
|
|
|
|
radix_tree_preload_end();
|
|
|
|
if (pos == blkcg)
|
|
goto success;
|
|
}
|
|
success:
|
|
blk_queue_exit(q);
|
|
ctx->bdev = bdev;
|
|
ctx->blkg = blkg;
|
|
ctx->body = input;
|
|
return 0;
|
|
|
|
fail_preloaded:
|
|
radix_tree_preload_end();
|
|
fail_unlock:
|
|
spin_unlock_irq(&q->queue_lock);
|
|
rcu_read_unlock();
|
|
fail_exit_queue:
|
|
blk_queue_exit(q);
|
|
fail:
|
|
blkdev_put_no_open(bdev);
|
|
/*
|
|
* 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;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_conf_prep);
|
|
|
|
/**
|
|
* 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->bdev->bd_queue->queue_lock) __releases(rcu)
|
|
{
|
|
spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock);
|
|
rcu_read_unlock();
|
|
blkdev_put_no_open(ctx->bdev);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_conf_finish);
|
|
|
|
static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < BLKG_IOSTAT_NR; i++) {
|
|
dst->bytes[i] = src->bytes[i];
|
|
dst->ios[i] = src->ios[i];
|
|
}
|
|
}
|
|
|
|
static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < BLKG_IOSTAT_NR; i++) {
|
|
dst->bytes[i] += src->bytes[i];
|
|
dst->ios[i] += src->ios[i];
|
|
}
|
|
}
|
|
|
|
static void blkg_iostat_sub(struct blkg_iostat *dst, struct blkg_iostat *src)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < BLKG_IOSTAT_NR; i++) {
|
|
dst->bytes[i] -= src->bytes[i];
|
|
dst->ios[i] -= src->ios[i];
|
|
}
|
|
}
|
|
|
|
static void blkcg_rstat_flush(struct cgroup_subsys_state *css, int cpu)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(css);
|
|
struct blkcg_gq *blkg;
|
|
|
|
/* Root-level stats are sourced from system-wide IO stats */
|
|
if (!cgroup_parent(css->cgroup))
|
|
return;
|
|
|
|
rcu_read_lock();
|
|
|
|
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
|
|
struct blkcg_gq *parent = blkg->parent;
|
|
struct blkg_iostat_set *bisc = per_cpu_ptr(blkg->iostat_cpu, cpu);
|
|
struct blkg_iostat cur, delta;
|
|
unsigned long flags;
|
|
unsigned int seq;
|
|
|
|
/* fetch the current per-cpu values */
|
|
do {
|
|
seq = u64_stats_fetch_begin(&bisc->sync);
|
|
blkg_iostat_set(&cur, &bisc->cur);
|
|
} while (u64_stats_fetch_retry(&bisc->sync, seq));
|
|
|
|
/* propagate percpu delta to global */
|
|
flags = u64_stats_update_begin_irqsave(&blkg->iostat.sync);
|
|
blkg_iostat_set(&delta, &cur);
|
|
blkg_iostat_sub(&delta, &bisc->last);
|
|
blkg_iostat_add(&blkg->iostat.cur, &delta);
|
|
blkg_iostat_add(&bisc->last, &delta);
|
|
u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags);
|
|
|
|
/* propagate global delta to parent (unless that's root) */
|
|
if (parent && parent->parent) {
|
|
flags = u64_stats_update_begin_irqsave(&parent->iostat.sync);
|
|
blkg_iostat_set(&delta, &blkg->iostat.cur);
|
|
blkg_iostat_sub(&delta, &blkg->iostat.last);
|
|
blkg_iostat_add(&parent->iostat.cur, &delta);
|
|
blkg_iostat_add(&blkg->iostat.last, &delta);
|
|
u64_stats_update_end_irqrestore(&parent->iostat.sync, flags);
|
|
}
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* We source root cgroup stats from the system-wide stats to avoid
|
|
* tracking the same information twice and incurring overhead when no
|
|
* cgroups are defined. For that reason, cgroup_rstat_flush in
|
|
* blkcg_print_stat does not actually fill out the iostat in the root
|
|
* cgroup's blkcg_gq.
|
|
*
|
|
* However, we would like to re-use the printing code between the root and
|
|
* non-root cgroups to the extent possible. For that reason, we simulate
|
|
* flushing the root cgroup's stats by explicitly filling in the iostat
|
|
* with disk level statistics.
|
|
*/
|
|
static void blkcg_fill_root_iostats(void)
|
|
{
|
|
struct class_dev_iter iter;
|
|
struct device *dev;
|
|
|
|
class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
|
|
while ((dev = class_dev_iter_next(&iter))) {
|
|
struct block_device *bdev = dev_to_bdev(dev);
|
|
struct blkcg_gq *blkg =
|
|
blk_queue_root_blkg(bdev_get_queue(bdev));
|
|
struct blkg_iostat tmp;
|
|
int cpu;
|
|
unsigned long flags;
|
|
|
|
memset(&tmp, 0, sizeof(tmp));
|
|
for_each_possible_cpu(cpu) {
|
|
struct disk_stats *cpu_dkstats;
|
|
|
|
cpu_dkstats = per_cpu_ptr(bdev->bd_stats, cpu);
|
|
tmp.ios[BLKG_IOSTAT_READ] +=
|
|
cpu_dkstats->ios[STAT_READ];
|
|
tmp.ios[BLKG_IOSTAT_WRITE] +=
|
|
cpu_dkstats->ios[STAT_WRITE];
|
|
tmp.ios[BLKG_IOSTAT_DISCARD] +=
|
|
cpu_dkstats->ios[STAT_DISCARD];
|
|
// convert sectors to bytes
|
|
tmp.bytes[BLKG_IOSTAT_READ] +=
|
|
cpu_dkstats->sectors[STAT_READ] << 9;
|
|
tmp.bytes[BLKG_IOSTAT_WRITE] +=
|
|
cpu_dkstats->sectors[STAT_WRITE] << 9;
|
|
tmp.bytes[BLKG_IOSTAT_DISCARD] +=
|
|
cpu_dkstats->sectors[STAT_DISCARD] << 9;
|
|
}
|
|
|
|
flags = u64_stats_update_begin_irqsave(&blkg->iostat.sync);
|
|
blkg_iostat_set(&blkg->iostat.cur, &tmp);
|
|
u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags);
|
|
}
|
|
}
|
|
|
|
static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s)
|
|
{
|
|
struct blkg_iostat_set *bis = &blkg->iostat;
|
|
u64 rbytes, wbytes, rios, wios, dbytes, dios;
|
|
const char *dname;
|
|
unsigned seq;
|
|
int i;
|
|
|
|
if (!blkg->online)
|
|
return;
|
|
|
|
dname = blkg_dev_name(blkg);
|
|
if (!dname)
|
|
return;
|
|
|
|
seq_printf(s, "%s ", dname);
|
|
|
|
do {
|
|
seq = u64_stats_fetch_begin(&bis->sync);
|
|
|
|
rbytes = bis->cur.bytes[BLKG_IOSTAT_READ];
|
|
wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE];
|
|
dbytes = bis->cur.bytes[BLKG_IOSTAT_DISCARD];
|
|
rios = bis->cur.ios[BLKG_IOSTAT_READ];
|
|
wios = bis->cur.ios[BLKG_IOSTAT_WRITE];
|
|
dios = bis->cur.ios[BLKG_IOSTAT_DISCARD];
|
|
} while (u64_stats_fetch_retry(&bis->sync, seq));
|
|
|
|
if (rbytes || wbytes || rios || wios) {
|
|
seq_printf(s, "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu",
|
|
rbytes, wbytes, rios, wios,
|
|
dbytes, dios);
|
|
}
|
|
|
|
if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) {
|
|
seq_printf(s, " use_delay=%d delay_nsec=%llu",
|
|
atomic_read(&blkg->use_delay),
|
|
atomic64_read(&blkg->delay_nsec));
|
|
}
|
|
|
|
for (i = 0; i < BLKCG_MAX_POLS; i++) {
|
|
struct blkcg_policy *pol = blkcg_policy[i];
|
|
|
|
if (!blkg->pd[i] || !pol->pd_stat_fn)
|
|
continue;
|
|
|
|
pol->pd_stat_fn(blkg->pd[i], s);
|
|
}
|
|
|
|
seq_puts(s, "\n");
|
|
}
|
|
|
|
static int blkcg_print_stat(struct seq_file *sf, void *v)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
|
|
struct blkcg_gq *blkg;
|
|
|
|
if (!seq_css(sf)->parent)
|
|
blkcg_fill_root_iostats();
|
|
else
|
|
cgroup_rstat_flush(blkcg->css.cgroup);
|
|
|
|
rcu_read_lock();
|
|
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
|
|
spin_lock_irq(&blkg->q->queue_lock);
|
|
blkcg_print_one_stat(blkg, sf);
|
|
spin_unlock_irq(&blkg->q->queue_lock);
|
|
}
|
|
rcu_read_unlock();
|
|
return 0;
|
|
}
|
|
|
|
static struct cftype blkcg_files[] = {
|
|
{
|
|
.name = "stat",
|
|
.seq_show = blkcg_print_stat,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
static struct cftype blkcg_legacy_files[] = {
|
|
{
|
|
.name = "reset_stats",
|
|
.write_u64 = blkcg_reset_stats,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
#ifdef CONFIG_CGROUP_WRITEBACK
|
|
struct list_head *blkcg_get_cgwb_list(struct cgroup_subsys_state *css)
|
|
{
|
|
return &css_to_blkcg(css)->cgwb_list;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 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_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().
|
|
*/
|
|
static void blkcg_destroy_blkgs(struct blkcg *blkcg)
|
|
{
|
|
might_sleep();
|
|
|
|
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 (need_resched() || !spin_trylock(&q->queue_lock)) {
|
|
/*
|
|
* Given that the system can accumulate a huge number
|
|
* of blkgs in pathological cases, check to see if we
|
|
* need to rescheduling to avoid softlockup.
|
|
*/
|
|
spin_unlock_irq(&blkcg->lock);
|
|
cond_resched();
|
|
spin_lock_irq(&blkcg->lock);
|
|
continue;
|
|
}
|
|
|
|
blkg_destroy(blkg);
|
|
spin_unlock(&q->queue_lock);
|
|
}
|
|
|
|
spin_unlock_irq(&blkcg->lock);
|
|
}
|
|
|
|
/**
|
|
* blkcg_pin_online - pin online state
|
|
* @blkcg_css: blkcg of interest
|
|
*
|
|
* While pinned, a blkcg is kept online. This is primarily used to
|
|
* impedance-match blkg and cgwb lifetimes so that blkg doesn't go offline
|
|
* while an associated cgwb is still active.
|
|
*/
|
|
void blkcg_pin_online(struct cgroup_subsys_state *blkcg_css)
|
|
{
|
|
refcount_inc(&css_to_blkcg(blkcg_css)->online_pin);
|
|
}
|
|
|
|
/**
|
|
* blkcg_unpin_online - unpin online state
|
|
* @blkcg_css: blkcg of interest
|
|
*
|
|
* This is primarily used to impedance-match blkg and cgwb lifetimes so
|
|
* that blkg doesn't go offline while an associated cgwb is still active.
|
|
* When this count goes to zero, all active cgwbs have finished so the
|
|
* blkcg can continue destruction by calling blkcg_destroy_blkgs().
|
|
*/
|
|
void blkcg_unpin_online(struct cgroup_subsys_state *blkcg_css)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(blkcg_css);
|
|
|
|
do {
|
|
if (!refcount_dec_and_test(&blkcg->online_pin))
|
|
break;
|
|
blkcg_destroy_blkgs(blkcg);
|
|
blkcg = blkcg_parent(blkcg);
|
|
} while (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)
|
|
{
|
|
/* this prevents anyone from attaching or migrating to this blkcg */
|
|
wb_blkcg_offline(css);
|
|
|
|
/* put the base online pin allowing step 2 to be triggered */
|
|
blkcg_unpin_online(css);
|
|
}
|
|
|
|
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);
|
|
refcount_set(&blkcg->online_pin, 1);
|
|
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);
|
|
#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;
|
|
}
|
|
|
|
static int blkcg_css_online(struct cgroup_subsys_state *css)
|
|
{
|
|
struct blkcg *parent = blkcg_parent(css_to_blkcg(css));
|
|
|
|
/*
|
|
* blkcg_pin_online() is used to delay blkcg offline so that blkgs
|
|
* don't go offline while cgwbs are still active on them. Pin the
|
|
* parent so that offline always happens towards the root.
|
|
*/
|
|
if (parent)
|
|
blkcg_pin_online(css);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* blkcg_init_queue - initialize blkcg part of request queue
|
|
* @q: request_queue to initialize
|
|
*
|
|
* Called from blk_alloc_queue(). 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;
|
|
|
|
INIT_LIST_HEAD(&q->blkg_list);
|
|
|
|
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. */
|
|
/* spin_lock_irq can serve as RCU read-side critical section. */
|
|
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);
|
|
|
|
if (preloaded)
|
|
radix_tree_preload_end();
|
|
|
|
ret = blk_ioprio_init(q);
|
|
if (ret)
|
|
goto err_destroy_all;
|
|
|
|
ret = blk_throtl_init(q);
|
|
if (ret)
|
|
goto err_destroy_all;
|
|
|
|
ret = blk_iolatency_init(q);
|
|
if (ret) {
|
|
blk_throtl_exit(q);
|
|
goto err_destroy_all;
|
|
}
|
|
|
|
return 0;
|
|
|
|
err_destroy_all:
|
|
blkg_destroy_all(q);
|
|
return ret;
|
|
err_unlock:
|
|
spin_unlock_irq(&q->queue_lock);
|
|
if (preloaded)
|
|
radix_tree_preload_end();
|
|
return PTR_ERR(blkg);
|
|
}
|
|
|
|
/**
|
|
* 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);
|
|
}
|
|
|
|
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_online = blkcg_css_online,
|
|
.css_offline = blkcg_css_offline,
|
|
.css_free = blkcg_css_free,
|
|
.css_rstat_flush = blkcg_rstat_flush,
|
|
.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, *pinned_blkg = NULL;
|
|
int ret;
|
|
|
|
if (blkcg_policy_enabled(q, pol))
|
|
return 0;
|
|
|
|
if (queue_is_mq(q))
|
|
blk_mq_freeze_queue(q);
|
|
retry:
|
|
spin_lock_irq(&q->queue_lock);
|
|
|
|
/* blkg_list is pushed at the head, reverse walk to allocate parents first */
|
|
list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) {
|
|
struct blkg_policy_data *pd;
|
|
|
|
if (blkg->pd[pol->plid])
|
|
continue;
|
|
|
|
/* If prealloc matches, use it; otherwise try GFP_NOWAIT */
|
|
if (blkg == pinned_blkg) {
|
|
pd = pd_prealloc;
|
|
pd_prealloc = NULL;
|
|
} else {
|
|
pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q,
|
|
blkg->blkcg);
|
|
}
|
|
|
|
if (!pd) {
|
|
/*
|
|
* GFP_NOWAIT failed. Free the existing one and
|
|
* prealloc for @blkg w/ GFP_KERNEL.
|
|
*/
|
|
if (pinned_blkg)
|
|
blkg_put(pinned_blkg);
|
|
blkg_get(blkg);
|
|
pinned_blkg = blkg;
|
|
|
|
spin_unlock_irq(&q->queue_lock);
|
|
|
|
if (pd_prealloc)
|
|
pol->pd_free_fn(pd_prealloc);
|
|
pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q,
|
|
blkg->blkcg);
|
|
if (pd_prealloc)
|
|
goto retry;
|
|
else
|
|
goto enomem;
|
|
}
|
|
|
|
blkg->pd[pol->plid] = pd;
|
|
pd->blkg = blkg;
|
|
pd->plid = pol->plid;
|
|
}
|
|
|
|
/* all allocated, init in the same order */
|
|
if (pol->pd_init_fn)
|
|
list_for_each_entry_reverse(blkg, &q->blkg_list, q_node)
|
|
pol->pd_init_fn(blkg->pd[pol->plid]);
|
|
|
|
__set_bit(pol->plid, q->blkcg_pols);
|
|
ret = 0;
|
|
|
|
spin_unlock_irq(&q->queue_lock);
|
|
out:
|
|
if (queue_is_mq(q))
|
|
blk_mq_unfreeze_queue(q);
|
|
if (pinned_blkg)
|
|
blkg_put(pinned_blkg);
|
|
if (pd_prealloc)
|
|
pol->pd_free_fn(pd_prealloc);
|
|
return ret;
|
|
|
|
enomem:
|
|
/* alloc failed, nothing's initialized yet, free everything */
|
|
spin_lock_irq(&q->queue_lock);
|
|
list_for_each_entry(blkg, &q->blkg_list, q_node) {
|
|
struct blkcg *blkcg = blkg->blkcg;
|
|
|
|
spin_lock(&blkcg->lock);
|
|
if (blkg->pd[pol->plid]) {
|
|
pol->pd_free_fn(blkg->pd[pol->plid]);
|
|
blkg->pd[pol->plid] = NULL;
|
|
}
|
|
spin_unlock(&blkcg->lock);
|
|
}
|
|
spin_unlock_irq(&q->queue_lock);
|
|
ret = -ENOMEM;
|
|
goto out;
|
|
}
|
|
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) {
|
|
struct blkcg *blkcg = blkg->blkcg;
|
|
|
|
spin_lock(&blkcg->lock);
|
|
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(&blkcg->lock);
|
|
}
|
|
|
|
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;
|
|
if (pol->cpd_init_fn)
|
|
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);
|
|
|
|
bool __blkcg_punt_bio_submit(struct bio *bio)
|
|
{
|
|
struct blkcg_gq *blkg = bio->bi_blkg;
|
|
|
|
/* consume the flag first */
|
|
bio->bi_opf &= ~REQ_CGROUP_PUNT;
|
|
|
|
/* never bounce for the root cgroup */
|
|
if (!blkg->parent)
|
|
return false;
|
|
|
|
spin_lock_bh(&blkg->async_bio_lock);
|
|
bio_list_add(&blkg->async_bios, bio);
|
|
spin_unlock_bh(&blkg->async_bio_lock);
|
|
|
|
queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work);
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/* negative use_delay means no scaling, see blkcg_set_delay() */
|
|
if (atomic_read(&blkg->use_delay) < 0)
|
|
return;
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
unsigned long pflags;
|
|
bool clamp;
|
|
u64 now = ktime_to_ns(ktime_get());
|
|
u64 exp;
|
|
u64 delay_nsec = 0;
|
|
int tok;
|
|
|
|
while (blkg->parent) {
|
|
int use_delay = atomic_read(&blkg->use_delay);
|
|
|
|
if (use_delay) {
|
|
u64 this_delay;
|
|
|
|
blkcg_scale_delay(blkg, now);
|
|
this_delay = atomic64_read(&blkg->delay_nsec);
|
|
if (this_delay > delay_nsec) {
|
|
delay_nsec = this_delay;
|
|
clamp = use_delay > 0;
|
|
}
|
|
}
|
|
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 0.25s. If there's 10's of seconds worth of delay then the
|
|
* tasks will be delayed for 0.25 second for every syscall. If
|
|
* blkcg_set_delay() was used as indicated by negative use_delay, the
|
|
* caller is responsible for regulating the range.
|
|
*/
|
|
if (clamp)
|
|
delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC);
|
|
|
|
if (use_memdelay)
|
|
psi_memstall_enter(&pflags);
|
|
|
|
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);
|
|
|
|
if (use_memdelay)
|
|
psi_memstall_leave(&pflags);
|
|
}
|
|
|
|
/**
|
|
* 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 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();
|
|
blkcg = css_to_blkcg(blkcg_css());
|
|
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 (current->throttle_queue != q) {
|
|
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
|
|
* @blkg: blkg of interest
|
|
* @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)
|
|
{
|
|
if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
|
|
return;
|
|
blkcg_scale_delay(blkg, now);
|
|
atomic64_add(delta, &blkg->delay_nsec);
|
|
}
|
|
|
|
/**
|
|
* blkg_tryget_closest - try and get a blkg ref on the closet blkg
|
|
* @bio: target bio
|
|
* @css: target css
|
|
*
|
|
* As the failure mode here is to walk up the blkg tree, this ensure that the
|
|
* blkg->parent pointers are always valid. This returns the blkg that it ended
|
|
* up taking a reference on or %NULL if no reference was taken.
|
|
*/
|
|
static inline struct blkcg_gq *blkg_tryget_closest(struct bio *bio,
|
|
struct cgroup_subsys_state *css)
|
|
{
|
|
struct blkcg_gq *blkg, *ret_blkg = NULL;
|
|
|
|
rcu_read_lock();
|
|
blkg = blkg_lookup_create(css_to_blkcg(css),
|
|
bdev_get_queue(bio->bi_bdev));
|
|
while (blkg) {
|
|
if (blkg_tryget(blkg)) {
|
|
ret_blkg = blkg;
|
|
break;
|
|
}
|
|
blkg = blkg->parent;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return ret_blkg;
|
|
}
|
|
|
|
/**
|
|
* bio_associate_blkg_from_css - associate a bio with a specified css
|
|
* @bio: target bio
|
|
* @css: target css
|
|
*
|
|
* Associate @bio with the blkg found by combining the css's blkg and the
|
|
* request_queue of the @bio. An association failure is handled by walking up
|
|
* the blkg tree. Therefore, the blkg associated can be anything between @blkg
|
|
* and q->root_blkg. This situation only happens when a cgroup is dying and
|
|
* then the remaining bios will spill to the closest alive blkg.
|
|
*
|
|
* A reference will be taken on the blkg and will be released when @bio is
|
|
* freed.
|
|
*/
|
|
void bio_associate_blkg_from_css(struct bio *bio,
|
|
struct cgroup_subsys_state *css)
|
|
{
|
|
if (bio->bi_blkg)
|
|
blkg_put(bio->bi_blkg);
|
|
|
|
if (css && css->parent) {
|
|
bio->bi_blkg = blkg_tryget_closest(bio, css);
|
|
} else {
|
|
blkg_get(bdev_get_queue(bio->bi_bdev)->root_blkg);
|
|
bio->bi_blkg = bdev_get_queue(bio->bi_bdev)->root_blkg;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css);
|
|
|
|
/**
|
|
* bio_associate_blkg - associate a bio with a blkg
|
|
* @bio: target bio
|
|
*
|
|
* Associate @bio with the blkg found from the bio's css and request_queue.
|
|
* If one is not found, bio_lookup_blkg() creates the blkg. If a blkg is
|
|
* already associated, the css is reused and association redone as the
|
|
* request_queue may have changed.
|
|
*/
|
|
void bio_associate_blkg(struct bio *bio)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
|
|
rcu_read_lock();
|
|
|
|
if (bio->bi_blkg)
|
|
css = bio_blkcg_css(bio);
|
|
else
|
|
css = blkcg_css();
|
|
|
|
bio_associate_blkg_from_css(bio, css);
|
|
|
|
rcu_read_unlock();
|
|
}
|
|
EXPORT_SYMBOL_GPL(bio_associate_blkg);
|
|
|
|
/**
|
|
* bio_clone_blkg_association - clone blkg association from src to dst bio
|
|
* @dst: destination bio
|
|
* @src: source bio
|
|
*/
|
|
void bio_clone_blkg_association(struct bio *dst, struct bio *src)
|
|
{
|
|
if (src->bi_blkg) {
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|
if (dst->bi_blkg)
|
|
blkg_put(dst->bi_blkg);
|
|
blkg_get(src->bi_blkg);
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|
dst->bi_blkg = src->bi_blkg;
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|
}
|
|
}
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|
EXPORT_SYMBOL_GPL(bio_clone_blkg_association);
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|
|
|
static int blk_cgroup_io_type(struct bio *bio)
|
|
{
|
|
if (op_is_discard(bio->bi_opf))
|
|
return BLKG_IOSTAT_DISCARD;
|
|
if (op_is_write(bio->bi_opf))
|
|
return BLKG_IOSTAT_WRITE;
|
|
return BLKG_IOSTAT_READ;
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|
}
|
|
|
|
void blk_cgroup_bio_start(struct bio *bio)
|
|
{
|
|
int rwd = blk_cgroup_io_type(bio), cpu;
|
|
struct blkg_iostat_set *bis;
|
|
unsigned long flags;
|
|
|
|
cpu = get_cpu();
|
|
bis = per_cpu_ptr(bio->bi_blkg->iostat_cpu, cpu);
|
|
flags = u64_stats_update_begin_irqsave(&bis->sync);
|
|
|
|
/*
|
|
* If the bio is flagged with BIO_CGROUP_ACCT it means this is a split
|
|
* bio and we would have already accounted for the size of the bio.
|
|
*/
|
|
if (!bio_flagged(bio, BIO_CGROUP_ACCT)) {
|
|
bio_set_flag(bio, BIO_CGROUP_ACCT);
|
|
bis->cur.bytes[rwd] += bio->bi_iter.bi_size;
|
|
}
|
|
bis->cur.ios[rwd]++;
|
|
|
|
u64_stats_update_end_irqrestore(&bis->sync, flags);
|
|
if (cgroup_subsys_on_dfl(io_cgrp_subsys))
|
|
cgroup_rstat_updated(bio->bi_blkg->blkcg->css.cgroup, cpu);
|
|
put_cpu();
|
|
}
|
|
|
|
bool blk_cgroup_congested(void)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
bool ret = false;
|
|
|
|
rcu_read_lock();
|
|
for (css = blkcg_css(); css; css = css->parent) {
|
|
if (atomic_read(&css->cgroup->congestion_count)) {
|
|
ret = true;
|
|
break;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
static int __init blkcg_init(void)
|
|
{
|
|
blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio",
|
|
WQ_MEM_RECLAIM | WQ_FREEZABLE |
|
|
WQ_UNBOUND | WQ_SYSFS, 0);
|
|
if (!blkcg_punt_bio_wq)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
subsys_initcall(blkcg_init);
|
|
|
|
module_param(blkcg_debug_stats, bool, 0644);
|
|
MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not");
|