664 lines
20 KiB
C
664 lines
20 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _BLK_CGROUP_H
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#define _BLK_CGROUP_H
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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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#include <linux/cgroup.h>
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#include <linux/percpu.h>
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#include <linux/percpu_counter.h>
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#include <linux/u64_stats_sync.h>
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#include <linux/seq_file.h>
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#include <linux/radix-tree.h>
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#include <linux/blkdev.h>
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#include <linux/atomic.h>
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#include <linux/kthread.h>
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#include <linux/fs.h>
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/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
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#define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
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/* Max limits for throttle policy */
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#define THROTL_IOPS_MAX UINT_MAX
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#ifdef CONFIG_BLK_CGROUP
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enum blkg_iostat_type {
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BLKG_IOSTAT_READ,
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BLKG_IOSTAT_WRITE,
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BLKG_IOSTAT_DISCARD,
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BLKG_IOSTAT_NR,
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};
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struct blkcg_gq;
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struct blkcg {
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struct cgroup_subsys_state css;
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spinlock_t lock;
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refcount_t online_pin;
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struct radix_tree_root blkg_tree;
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struct blkcg_gq __rcu *blkg_hint;
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struct hlist_head blkg_list;
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struct blkcg_policy_data *cpd[BLKCG_MAX_POLS];
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struct list_head all_blkcgs_node;
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#ifdef CONFIG_CGROUP_WRITEBACK
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struct list_head cgwb_list;
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#endif
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};
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struct blkg_iostat {
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u64 bytes[BLKG_IOSTAT_NR];
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u64 ios[BLKG_IOSTAT_NR];
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};
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struct blkg_iostat_set {
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struct u64_stats_sync sync;
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struct blkg_iostat cur;
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struct blkg_iostat last;
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};
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/*
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* A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
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* request_queue (q). This is used by blkcg policies which need to track
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* information per blkcg - q pair.
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*
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* There can be multiple active blkcg policies and each blkg:policy pair is
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* represented by a blkg_policy_data which is allocated and freed by each
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* policy's pd_alloc/free_fn() methods. A policy can allocate private data
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* area by allocating larger data structure which embeds blkg_policy_data
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* at the beginning.
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*/
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struct blkg_policy_data {
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/* the blkg and policy id this per-policy data belongs to */
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struct blkcg_gq *blkg;
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int plid;
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};
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/*
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* Policies that need to keep per-blkcg data which is independent from any
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* request_queue associated to it should implement cpd_alloc/free_fn()
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* methods. A policy can allocate private data area by allocating larger
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* data structure which embeds blkcg_policy_data at the beginning.
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* cpd_init() is invoked to let each policy handle per-blkcg data.
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*/
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struct blkcg_policy_data {
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/* the blkcg and policy id this per-policy data belongs to */
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struct blkcg *blkcg;
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int plid;
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};
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/* association between a blk cgroup and a request queue */
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struct blkcg_gq {
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/* Pointer to the associated request_queue */
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struct request_queue *q;
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struct list_head q_node;
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struct hlist_node blkcg_node;
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struct blkcg *blkcg;
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/* all non-root blkcg_gq's are guaranteed to have access to parent */
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struct blkcg_gq *parent;
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/* reference count */
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struct percpu_ref refcnt;
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/* is this blkg online? protected by both blkcg and q locks */
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bool online;
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struct blkg_iostat_set __percpu *iostat_cpu;
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struct blkg_iostat_set iostat;
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struct blkg_policy_data *pd[BLKCG_MAX_POLS];
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spinlock_t async_bio_lock;
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struct bio_list async_bios;
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struct work_struct async_bio_work;
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atomic_t use_delay;
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atomic64_t delay_nsec;
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atomic64_t delay_start;
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u64 last_delay;
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int last_use;
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struct rcu_head rcu_head;
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};
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typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
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typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
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typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
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typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
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typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp,
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struct request_queue *q, struct blkcg *blkcg);
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typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
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typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
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typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
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typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
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typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
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typedef size_t (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd, char *buf,
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size_t size);
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struct blkcg_policy {
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int plid;
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/* cgroup files for the policy */
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struct cftype *dfl_cftypes;
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struct cftype *legacy_cftypes;
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/* operations */
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blkcg_pol_alloc_cpd_fn *cpd_alloc_fn;
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blkcg_pol_init_cpd_fn *cpd_init_fn;
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blkcg_pol_free_cpd_fn *cpd_free_fn;
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blkcg_pol_bind_cpd_fn *cpd_bind_fn;
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blkcg_pol_alloc_pd_fn *pd_alloc_fn;
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blkcg_pol_init_pd_fn *pd_init_fn;
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blkcg_pol_online_pd_fn *pd_online_fn;
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blkcg_pol_offline_pd_fn *pd_offline_fn;
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blkcg_pol_free_pd_fn *pd_free_fn;
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blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
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blkcg_pol_stat_pd_fn *pd_stat_fn;
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};
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extern struct blkcg blkcg_root;
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extern struct cgroup_subsys_state * const blkcg_root_css;
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extern bool blkcg_debug_stats;
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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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int blkcg_init_queue(struct request_queue *q);
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void blkcg_exit_queue(struct request_queue *q);
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/* Blkio controller policy registration */
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int blkcg_policy_register(struct blkcg_policy *pol);
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void blkcg_policy_unregister(struct blkcg_policy *pol);
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int blkcg_activate_policy(struct request_queue *q,
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const struct blkcg_policy *pol);
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void blkcg_deactivate_policy(struct request_queue *q,
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const struct blkcg_policy *pol);
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const char *blkg_dev_name(struct blkcg_gq *blkg);
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void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
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u64 (*prfill)(struct seq_file *,
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struct blkg_policy_data *, int),
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const struct blkcg_policy *pol, int data,
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bool show_total);
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u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
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struct blkg_conf_ctx {
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struct gendisk *disk;
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struct blkcg_gq *blkg;
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char *body;
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};
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struct gendisk *blkcg_conf_get_disk(char **inputp);
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int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
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char *input, struct blkg_conf_ctx *ctx);
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void blkg_conf_finish(struct blkg_conf_ctx *ctx);
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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 inline 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 inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
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{
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return css ? container_of(css, struct blkcg, css) : NULL;
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}
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/**
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* __bio_blkcg - internal, inconsistent version to get blkcg
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*
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* DO NOT USE.
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* This function is inconsistent and consequently is dangerous to use. The
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* first part of the function returns a blkcg where a reference is owned by the
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* bio. This means it does not need to be rcu protected as it cannot go away
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* with the bio owning a reference to it. However, the latter potentially gets
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* it from task_css(). This can race against task migration and the cgroup
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* dying. It is also semantically different as it must be called rcu protected
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* and is susceptible to failure when trying to get a reference to it.
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* Therefore, it is not ok to assume that *_get() will always succeed on the
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* blkcg returned here.
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*/
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static inline struct blkcg *__bio_blkcg(struct bio *bio)
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{
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if (bio && bio->bi_blkg)
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return bio->bi_blkg->blkcg;
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return css_to_blkcg(blkcg_css());
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}
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/**
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* bio_blkcg - grab the blkcg associated with a bio
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* @bio: target bio
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*
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* This returns the blkcg associated with a bio, %NULL if not associated.
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* Callers are expected to either handle %NULL or know association has been
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* done prior to calling this.
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*/
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static inline struct blkcg *bio_blkcg(struct bio *bio)
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{
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if (bio && bio->bi_blkg)
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return bio->bi_blkg->blkcg;
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return NULL;
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}
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static inline bool blk_cgroup_congested(void)
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{
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struct cgroup_subsys_state *css;
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bool ret = false;
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rcu_read_lock();
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css = kthread_blkcg();
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if (!css)
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css = task_css(current, io_cgrp_id);
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while (css) {
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if (atomic_read(&css->cgroup->congestion_count)) {
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ret = true;
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break;
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}
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css = css->parent;
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}
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rcu_read_unlock();
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return ret;
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}
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/**
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* bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
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* @return: true if this bio needs to be submitted with the root blkg context.
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*
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* In order to avoid priority inversions we sometimes need to issue a bio as if
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* it were attached to the root blkg, and then backcharge to the actual owning
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* blkg. The idea is we do bio_blkcg() to look up the actual context for the
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* bio and attach the appropriate blkg to the bio. Then we call this helper and
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* if it is true run with the root blkg for that queue and then do any
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* backcharging to the originating cgroup once the io is complete.
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*/
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static inline bool bio_issue_as_root_blkg(struct bio *bio)
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{
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return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
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}
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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_lookup - internal version of blkg_lookup()
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* @blkcg: blkcg of interest
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* @q: request_queue of interest
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* @update_hint: whether to update lookup hint with the result or not
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*
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* This is internal version and shouldn't be used by policy
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* implementations. Looks up blkgs for the @blkcg - @q pair regardless of
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* @q's bypass state. If @update_hint is %true, the caller should be
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* holding @q->queue_lock and lookup hint is updated on success.
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*/
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static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
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struct request_queue *q,
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bool update_hint)
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{
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struct blkcg_gq *blkg;
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if (blkcg == &blkcg_root)
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return q->root_blkg;
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blkg = rcu_dereference(blkcg->blkg_hint);
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if (blkg && blkg->q == q)
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return blkg;
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return blkg_lookup_slowpath(blkcg, q, update_hint);
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}
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/**
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* blkg_lookup - lookup blkg for the specified blkcg - q pair
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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. This function should be called
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* under RCU read lock.
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*/
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static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
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struct request_queue *q)
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{
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WARN_ON_ONCE(!rcu_read_lock_held());
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return __blkg_lookup(blkcg, q, false);
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}
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/**
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* blk_queue_root_blkg - return blkg for the (blkcg_root, @q) pair
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* @q: request_queue of interest
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*
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* Lookup blkg for @q at the root level. See also blkg_lookup().
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*/
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static inline struct blkcg_gq *blk_queue_root_blkg(struct request_queue *q)
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{
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return q->root_blkg;
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}
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/**
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* blkg_to_pdata - get policy private data
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* @blkg: blkg of interest
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* @pol: policy of interest
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*
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* Return pointer to private data associated with the @blkg-@pol pair.
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*/
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static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
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struct blkcg_policy *pol)
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{
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return blkg ? blkg->pd[pol->plid] : NULL;
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}
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static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
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struct blkcg_policy *pol)
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{
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return blkcg ? blkcg->cpd[pol->plid] : NULL;
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}
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/**
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* pdata_to_blkg - get blkg associated with policy private data
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* @pd: policy private data of interest
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*
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* @pd is policy private data. Determine the blkg it's associated with.
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*/
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static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
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{
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return pd ? pd->blkg : NULL;
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}
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static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
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{
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return cpd ? cpd->blkcg : NULL;
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}
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extern void blkcg_destroy_blkgs(struct blkcg *blkcg);
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/**
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* blkcg_pin_online - pin online state
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* @blkcg: blkcg of interest
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*
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* While pinned, a blkcg is kept online. This is primarily used to
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* impedance-match blkg and cgwb lifetimes so that blkg doesn't go offline
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* while an associated cgwb is still active.
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*/
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static inline void blkcg_pin_online(struct blkcg *blkcg)
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{
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refcount_inc(&blkcg->online_pin);
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}
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/**
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* blkcg_unpin_online - unpin online state
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* @blkcg: blkcg of interest
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*
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* This is primarily used to impedance-match blkg and cgwb lifetimes so
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* that blkg doesn't go offline while an associated cgwb is still active.
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* When this count goes to zero, all active cgwbs have finished so the
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* blkcg can continue destruction by calling blkcg_destroy_blkgs().
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*/
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static inline void blkcg_unpin_online(struct blkcg *blkcg)
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{
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do {
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if (!refcount_dec_and_test(&blkcg->online_pin))
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break;
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blkcg_destroy_blkgs(blkcg);
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blkcg = blkcg_parent(blkcg);
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} while (blkcg);
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}
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/**
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* blkg_path - format cgroup path of blkg
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* @blkg: blkg of interest
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* @buf: target buffer
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* @buflen: target buffer length
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*
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* Format the path of the cgroup of @blkg into @buf.
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*/
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static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
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{
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return cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
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}
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/**
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* blkg_get - get a blkg reference
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* @blkg: blkg to get
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*
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* The caller should be holding an existing reference.
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*/
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static inline void blkg_get(struct blkcg_gq *blkg)
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{
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percpu_ref_get(&blkg->refcnt);
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}
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/**
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* blkg_tryget - try and get a blkg reference
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* @blkg: blkg to get
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*
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* This is for use when doing an RCU lookup of the blkg. We may be in the midst
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* of freeing this blkg, so we can only use it if the refcnt is not zero.
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*/
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static inline bool blkg_tryget(struct blkcg_gq *blkg)
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{
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return blkg && percpu_ref_tryget(&blkg->refcnt);
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}
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/**
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* blkg_put - put a blkg reference
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* @blkg: blkg to put
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*/
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static inline void blkg_put(struct blkcg_gq *blkg)
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{
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percpu_ref_put(&blkg->refcnt);
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}
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/**
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* blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
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* @d_blkg: loop cursor pointing to the current descendant
|
|
* @pos_css: used for iteration
|
|
* @p_blkg: target blkg to walk descendants of
|
|
*
|
|
* Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
|
|
* read locked. If called under either blkcg or queue lock, the iteration
|
|
* is guaranteed to include all and only online blkgs. The caller may
|
|
* update @pos_css by calling css_rightmost_descendant() to skip subtree.
|
|
* @p_blkg is included in the iteration and the first node to be visited.
|
|
*/
|
|
#define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
|
|
css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
|
|
if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
|
|
(p_blkg)->q, false)))
|
|
|
|
/**
|
|
* blkg_for_each_descendant_post - post-order walk of a blkg's descendants
|
|
* @d_blkg: loop cursor pointing to the current descendant
|
|
* @pos_css: used for iteration
|
|
* @p_blkg: target blkg to walk descendants of
|
|
*
|
|
* Similar to blkg_for_each_descendant_pre() but performs post-order
|
|
* traversal instead. Synchronization rules are the same. @p_blkg is
|
|
* included in the iteration and the last node to be visited.
|
|
*/
|
|
#define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
|
|
css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
|
|
if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
|
|
(p_blkg)->q, false)))
|
|
|
|
bool __blkcg_punt_bio_submit(struct bio *bio);
|
|
|
|
static inline bool blkcg_punt_bio_submit(struct bio *bio)
|
|
{
|
|
if (bio->bi_opf & REQ_CGROUP_PUNT)
|
|
return __blkcg_punt_bio_submit(bio);
|
|
else
|
|
return false;
|
|
}
|
|
|
|
static inline void blkcg_bio_issue_init(struct bio *bio)
|
|
{
|
|
bio_issue_init(&bio->bi_issue, bio_sectors(bio));
|
|
}
|
|
|
|
static inline void blkcg_use_delay(struct blkcg_gq *blkg)
|
|
{
|
|
if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
|
|
return;
|
|
if (atomic_add_return(1, &blkg->use_delay) == 1)
|
|
atomic_inc(&blkg->blkcg->css.cgroup->congestion_count);
|
|
}
|
|
|
|
static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
|
|
{
|
|
int old = atomic_read(&blkg->use_delay);
|
|
|
|
if (WARN_ON_ONCE(old < 0))
|
|
return 0;
|
|
if (old == 0)
|
|
return 0;
|
|
|
|
/*
|
|
* We do this song and dance because we can race with somebody else
|
|
* adding or removing delay. If we just did an atomic_dec we'd end up
|
|
* negative and we'd already be in trouble. We need to subtract 1 and
|
|
* then check to see if we were the last delay so we can drop the
|
|
* congestion count on the cgroup.
|
|
*/
|
|
while (old) {
|
|
int cur = atomic_cmpxchg(&blkg->use_delay, old, old - 1);
|
|
if (cur == old)
|
|
break;
|
|
old = cur;
|
|
}
|
|
|
|
if (old == 0)
|
|
return 0;
|
|
if (old == 1)
|
|
atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* blkcg_set_delay - Enable allocator delay mechanism with the specified delay amount
|
|
* @blkg: target blkg
|
|
* @delay: delay duration in nsecs
|
|
*
|
|
* When enabled with this function, the delay is not decayed and must be
|
|
* explicitly cleared with blkcg_clear_delay(). Must not be mixed with
|
|
* blkcg_[un]use_delay() and blkcg_add_delay() usages.
|
|
*/
|
|
static inline void blkcg_set_delay(struct blkcg_gq *blkg, u64 delay)
|
|
{
|
|
int old = atomic_read(&blkg->use_delay);
|
|
|
|
/* We only want 1 person setting the congestion count for this blkg. */
|
|
if (!old && atomic_cmpxchg(&blkg->use_delay, old, -1) == old)
|
|
atomic_inc(&blkg->blkcg->css.cgroup->congestion_count);
|
|
|
|
atomic64_set(&blkg->delay_nsec, delay);
|
|
}
|
|
|
|
/**
|
|
* blkcg_clear_delay - Disable allocator delay mechanism
|
|
* @blkg: target blkg
|
|
*
|
|
* Disable use_delay mechanism. See blkcg_set_delay().
|
|
*/
|
|
static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
|
|
{
|
|
int old = atomic_read(&blkg->use_delay);
|
|
|
|
/* We only want 1 person clearing the congestion count for this blkg. */
|
|
if (old && atomic_cmpxchg(&blkg->use_delay, old, 0) == old)
|
|
atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
|
|
}
|
|
|
|
void blk_cgroup_bio_start(struct bio *bio);
|
|
void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
|
|
void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay);
|
|
void blkcg_maybe_throttle_current(void);
|
|
#else /* CONFIG_BLK_CGROUP */
|
|
|
|
struct blkcg {
|
|
};
|
|
|
|
struct blkg_policy_data {
|
|
};
|
|
|
|
struct blkcg_policy_data {
|
|
};
|
|
|
|
struct blkcg_gq {
|
|
};
|
|
|
|
struct blkcg_policy {
|
|
};
|
|
|
|
#define blkcg_root_css ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))
|
|
|
|
static inline void blkcg_maybe_throttle_current(void) { }
|
|
static inline bool blk_cgroup_congested(void) { return false; }
|
|
|
|
#ifdef CONFIG_BLOCK
|
|
|
|
static inline void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) { }
|
|
|
|
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
|
|
static inline struct blkcg_gq *blk_queue_root_blkg(struct request_queue *q)
|
|
{ return NULL; }
|
|
static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
|
|
static inline void blkcg_exit_queue(struct request_queue *q) { }
|
|
static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
|
|
static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
|
|
static inline int blkcg_activate_policy(struct request_queue *q,
|
|
const struct blkcg_policy *pol) { return 0; }
|
|
static inline void blkcg_deactivate_policy(struct request_queue *q,
|
|
const struct blkcg_policy *pol) { }
|
|
|
|
static inline struct blkcg *__bio_blkcg(struct bio *bio) { return NULL; }
|
|
static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
|
|
|
|
static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
|
|
struct blkcg_policy *pol) { return NULL; }
|
|
static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
|
|
static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
|
|
static inline void blkg_get(struct blkcg_gq *blkg) { }
|
|
static inline void blkg_put(struct blkcg_gq *blkg) { }
|
|
|
|
static inline bool blkcg_punt_bio_submit(struct bio *bio) { return false; }
|
|
static inline void blkcg_bio_issue_init(struct bio *bio) { }
|
|
static inline void blk_cgroup_bio_start(struct bio *bio) { }
|
|
|
|
#define blk_queue_for_each_rl(rl, q) \
|
|
for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
|
|
|
|
#endif /* CONFIG_BLOCK */
|
|
#endif /* CONFIG_BLK_CGROUP */
|
|
#endif /* _BLK_CGROUP_H */
|