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![Tejun Heo](/assets/img/avatar_default.png)
blkcg->cgwb_refcnt is used to delay blkcg offlining so that blkgs don't get offlined while there are active cgwbs on them. However, it ends up making offlining unordered sometimes causing parents to be offlined before children. Let's fix this by making child blkcgs pin the parents' online states. Note that pin/unpin names are chosen over get/put intentionally because css uses get/put online for something different. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
1736 lines
45 KiB
C
1736 lines
45 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/genhd.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/blk-cgroup.h>
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#include <linux/tracehook.h>
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#include <linux/psi.h>
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#include "blk.h"
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#define MAX_KEY_LEN 100
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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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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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/**
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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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int i;
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if (!blkg)
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return;
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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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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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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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wb_congested_put(blkg->wb_congested);
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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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/* 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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while ((bio = bio_list_pop(&bios)))
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submit_bio(bio);
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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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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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struct bdi_writeback_congested *wb_congested;
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int i, ret;
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WARN_ON_ONCE(!rcu_read_lock_held());
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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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wb_congested = wb_congested_get_create(q->backing_dev_info,
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blkcg->css.id,
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GFP_NOWAIT | __GFP_NOWARN);
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if (!wb_congested) {
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ret = -ENOMEM;
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goto err_put_css;
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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_congested;
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}
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}
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blkg = new_blkg;
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blkg->wb_congested = wb_congested;
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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_congested;
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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_congested:
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wb_congested_put(wb_congested);
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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 @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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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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WARN_ON_ONCE(!rcu_read_lock_held());
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lockdep_assert_held(&q->queue_lock);
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blkg = __blkg_lookup(blkcg, q, true);
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if (blkg)
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return blkg;
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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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return ret_blkg;
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if (pos == blkcg)
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return blkg;
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}
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}
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/**
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* blkg_lookup_create - find or create a blkg
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* @blkcg: target block cgroup
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* @q: target request_queue
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*
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* This looks up or creates the blkg representing the unique pair
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* of the blkcg and the request_queue.
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*/
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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 = blkg_lookup(blkcg, q);
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if (unlikely(!blkg)) {
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unsigned long flags;
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spin_lock_irqsave(&q->queue_lock, flags);
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blkg = __blkg_lookup_create(blkcg, q);
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spin_unlock_irqrestore(&q->queue_lock, flags);
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}
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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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/*
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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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/*
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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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*/
|
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static void blkg_destroy_all(struct request_queue *q)
|
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{
|
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struct blkcg_gq *blkg, *n;
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|
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spin_lock_irq(&q->queue_lock);
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list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
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struct blkcg *blkcg = blkg->blkcg;
|
|
|
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spin_lock(&blkcg->lock);
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blkg_destroy(blkg);
|
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spin_unlock(&blkcg->lock);
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}
|
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|
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q->root_blkg = NULL;
|
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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);
|
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struct blkcg_gq *blkg;
|
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int i, cpu;
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|
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mutex_lock(&blkcg_pol_mutex);
|
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spin_lock_irq(&blkcg->lock);
|
|
|
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/*
|
|
* Note that stat reset is racy - it doesn't synchronize against
|
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* stat updates. This is a debug feature which shouldn't exist
|
|
* anyway. If you get hit by a race, retry.
|
|
*/
|
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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)
|
|
{
|
|
/* 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);
|
|
|
|
/* 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
|
|
* @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 gendisk. *@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 gendisk *blkcg_conf_get_disk(char **inputp)
|
|
{
|
|
char *input = *inputp;
|
|
unsigned int major, minor;
|
|
struct gendisk *disk;
|
|
int key_len, part;
|
|
|
|
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);
|
|
|
|
disk = get_gendisk(MKDEV(major, minor), &part);
|
|
if (!disk)
|
|
return ERR_PTR(-ENODEV);
|
|
if (part) {
|
|
put_disk_and_module(disk);
|
|
return ERR_PTR(-ENODEV);
|
|
}
|
|
|
|
*inputp = input;
|
|
return disk;
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
int ret;
|
|
|
|
disk = blkcg_conf_get_disk(&input);
|
|
if (IS_ERR(disk))
|
|
return PTR_ERR(disk);
|
|
|
|
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 (IS_ERR(blkg)) {
|
|
ret = PTR_ERR(blkg);
|
|
goto fail_unlock;
|
|
}
|
|
}
|
|
|
|
if (pos == blkcg)
|
|
goto success;
|
|
}
|
|
success:
|
|
ctx->disk = disk;
|
|
ctx->blkg = blkg;
|
|
ctx->body = input;
|
|
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;
|
|
}
|
|
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->disk->queue->queue_lock) __releases(rcu)
|
|
{
|
|
spin_unlock_irq(&ctx->disk->queue->queue_lock);
|
|
rcu_read_unlock();
|
|
put_disk_and_module(ctx->disk);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blkg_conf_finish);
|
|
|
|
static int blkcg_print_stat(struct seq_file *sf, void *v)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
|
|
struct blkcg_gq *blkg;
|
|
|
|
cgroup_rstat_flush(blkcg->css.cgroup);
|
|
rcu_read_lock();
|
|
|
|
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
|
|
struct blkg_iostat_set *bis = &blkg->iostat;
|
|
const char *dname;
|
|
char *buf;
|
|
u64 rbytes, wbytes, rios, wios, dbytes, dios;
|
|
size_t size = seq_get_buf(sf, &buf), off = 0;
|
|
int i;
|
|
bool has_stats = false;
|
|
unsigned seq;
|
|
|
|
spin_lock_irq(&blkg->q->queue_lock);
|
|
|
|
if (!blkg->online)
|
|
goto skip;
|
|
|
|
dname = blkg_dev_name(blkg);
|
|
if (!dname)
|
|
goto skip;
|
|
|
|
/*
|
|
* 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);
|
|
|
|
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) {
|
|
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 && 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;
|
|
}
|
|
|
|
if (has_stats) {
|
|
if (off < size - 1) {
|
|
off += scnprintf(buf+off, size-off, "\n");
|
|
seq_commit(sf, off);
|
|
} else {
|
|
seq_commit(sf, -1);
|
|
}
|
|
}
|
|
skip:
|
|
spin_unlock_irq(&blkg->q->queue_lock);
|
|
}
|
|
|
|
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 online pin allowing step 2 to be triggered */
|
|
blkcg_unpin_online(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);
|
|
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 *blkcg = css_to_blkcg(css);
|
|
struct blkcg *parent = blkcg_parent(blkcg);
|
|
|
|
/*
|
|
* 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(parent);
|
|
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;
|
|
|
|
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_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 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;
|
|
|
|
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 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 */
|
|
u64_stats_update_begin(&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(&blkg->iostat.sync);
|
|
|
|
/* propagate global delta to parent */
|
|
if (parent) {
|
|
u64_stats_update_begin(&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(&parent->iostat.sync);
|
|
}
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
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,
|
|
.can_attach = blkcg_can_attach,
|
|
.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) {
|
|
if (blkg->pd[pol->plid]) {
|
|
pol->pd_free_fn(blkg->pd[pol->plid]);
|
|
blkg->pd[pol->plid] = NULL;
|
|
}
|
|
}
|
|
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) {
|
|
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;
|
|
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);
|
|
|
|
/*
|
|
* 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;
|
|
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);
|
|
|
|
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 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
|
|
* @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)
|
|
{
|
|
blkcg_scale_delay(blkg, now);
|
|
atomic64_add(delta, &blkg->delay_nsec);
|
|
}
|
|
|
|
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");
|