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![Tejun Heo](/assets/img/avatar_default.png)
Currently, when the last reference of a blkcg_gq is put, all then release operations sans the actual freeing happen directly in blkg_put(). As blkg_put() may be called under queue_lock, all pd_exit_fn()s may be too. This makes it impossible for pd_exit_fn()s to use del_timer_sync() on timers which grab the queue_lock which is an irq-safe lock due to the deadlock possibility described in the comment on top of del_timer_sync(). This can be easily avoided by perfoming the release operations in the RCU callback instead of directly from blkg_put(). This patch moves the blkcg_gq release operations to the RCU callback. As this leaves __blkg_release() with only call_rcu() invocation, blkg_rcu_free() is renamed to __blkg_release_rcu(), exported and call_rcu() invocation is now done directly from blkg_put() instead of going through __blkg_release() which is removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
599 lines
17 KiB
C
599 lines
17 KiB
C
#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/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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/* Max limits for throttle policy */
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#define THROTL_IOPS_MAX UINT_MAX
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/* CFQ specific, out here for blkcg->cfq_weight */
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#define CFQ_WEIGHT_MIN 10
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#define CFQ_WEIGHT_MAX 1000
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#define CFQ_WEIGHT_DEFAULT 500
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#ifdef CONFIG_BLK_CGROUP
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enum blkg_rwstat_type {
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BLKG_RWSTAT_READ,
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BLKG_RWSTAT_WRITE,
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BLKG_RWSTAT_SYNC,
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BLKG_RWSTAT_ASYNC,
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BLKG_RWSTAT_NR,
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BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_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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struct radix_tree_root blkg_tree;
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struct blkcg_gq *blkg_hint;
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struct hlist_head blkg_list;
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/* for policies to test whether associated blkcg has changed */
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uint64_t id;
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/* TODO: per-policy storage in blkcg */
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unsigned int cfq_weight; /* belongs to cfq */
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unsigned int cfq_leaf_weight;
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};
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struct blkg_stat {
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struct u64_stats_sync syncp;
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uint64_t cnt;
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};
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struct blkg_rwstat {
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struct u64_stats_sync syncp;
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uint64_t cnt[BLKG_RWSTAT_NR];
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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 has its private
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* data on each blkg, the size of which is determined by
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* blkcg_policy->pd_size. blkcg core allocates and frees such areas
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* together with blkg and invokes pd_init/exit_fn() methods.
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*
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* Such private data must embed struct blkg_policy_data (pd) at the
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* beginning and pd_size can't be smaller than pd.
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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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/* used during policy activation */
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struct list_head alloc_node;
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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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/* request allocation list for this blkcg-q pair */
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struct request_list rl;
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/* reference count */
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int 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_policy_data *pd[BLKCG_MAX_POLS];
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struct rcu_head rcu_head;
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};
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typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
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typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
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typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
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typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
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typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
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struct blkcg_policy {
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int plid;
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/* policy specific private data size */
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size_t pd_size;
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/* cgroup files for the policy */
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struct cftype *cftypes;
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/* operations */
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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_exit_pd_fn *pd_exit_fn;
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blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
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};
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extern struct blkcg blkcg_root;
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struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
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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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int blkcg_init_queue(struct request_queue *q);
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void blkcg_drain_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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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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u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
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const struct blkg_rwstat *rwstat);
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u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
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u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
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int off);
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u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
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struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
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int off);
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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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u64 v;
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};
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int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
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const char *input, struct blkg_conf_ctx *ctx);
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void blkg_conf_finish(struct blkg_conf_ctx *ctx);
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static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
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{
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return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
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struct blkcg, css);
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}
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static inline struct blkcg *task_blkcg(struct task_struct *tsk)
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{
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return container_of(task_subsys_state(tsk, blkio_subsys_id),
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struct blkcg, css);
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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_css)
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return container_of(bio->bi_css, struct blkcg, css);
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return task_blkcg(current);
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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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struct cgroup *pcg = blkcg->css.cgroup->parent;
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return pcg ? cgroup_to_blkcg(pcg) : NULL;
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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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/**
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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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/**
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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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int ret;
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ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
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if (ret)
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strncpy(buf, "<unavailable>", buflen);
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return ret;
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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 queue_lock and 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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lockdep_assert_held(blkg->q->queue_lock);
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WARN_ON_ONCE(!blkg->refcnt);
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blkg->refcnt++;
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}
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void __blkg_release_rcu(struct rcu_head *rcu);
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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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* The caller should be holding queue_lock.
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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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lockdep_assert_held(blkg->q->queue_lock);
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WARN_ON_ONCE(blkg->refcnt <= 0);
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if (!--blkg->refcnt)
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call_rcu(&blkg->rcu_head, __blkg_release_rcu);
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}
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struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
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bool update_hint);
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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
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* @pos_cgrp: used for iteration
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* @p_blkg: target blkg to walk descendants of
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*
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* Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
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* read locked. If called under either blkcg or queue lock, the iteration
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* is guaranteed to include all and only online blkgs. The caller may
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* update @pos_cgrp by calling cgroup_rightmost_descendant() to skip
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* subtree.
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*/
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#define blkg_for_each_descendant_pre(d_blkg, pos_cgrp, p_blkg) \
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cgroup_for_each_descendant_pre((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \
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if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \
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(p_blkg)->q, false)))
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/**
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* blkg_for_each_descendant_post - post-order walk of a blkg's descendants
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* @d_blkg: loop cursor pointing to the current descendant
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* @pos_cgrp: used for iteration
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* @p_blkg: target blkg to walk descendants of
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*
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* Similar to blkg_for_each_descendant_pre() but performs post-order
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* traversal instead. Synchronization rules are the same.
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*/
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#define blkg_for_each_descendant_post(d_blkg, pos_cgrp, p_blkg) \
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cgroup_for_each_descendant_post((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \
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if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \
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(p_blkg)->q, false)))
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/**
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* blk_get_rl - get request_list to use
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* @q: request_queue of interest
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* @bio: bio which will be attached to the allocated request (may be %NULL)
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*
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* The caller wants to allocate a request from @q to use for @bio. Find
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* the request_list to use and obtain a reference on it. Should be called
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* under queue_lock. This function is guaranteed to return non-%NULL
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* request_list.
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*/
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static inline struct request_list *blk_get_rl(struct request_queue *q,
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struct bio *bio)
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{
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struct blkcg *blkcg;
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struct blkcg_gq *blkg;
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rcu_read_lock();
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blkcg = bio_blkcg(bio);
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/* bypass blkg lookup and use @q->root_rl directly for root */
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if (blkcg == &blkcg_root)
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goto root_rl;
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/*
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* Try to use blkg->rl. blkg lookup may fail under memory pressure
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* or if either the blkcg or queue is going away. Fall back to
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* root_rl in such cases.
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*/
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blkg = blkg_lookup_create(blkcg, q);
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if (unlikely(IS_ERR(blkg)))
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goto root_rl;
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blkg_get(blkg);
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rcu_read_unlock();
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return &blkg->rl;
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root_rl:
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rcu_read_unlock();
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return &q->root_rl;
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}
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/**
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* blk_put_rl - put request_list
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* @rl: request_list to put
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*
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* Put the reference acquired by blk_get_rl(). Should be called under
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* queue_lock.
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*/
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static inline void blk_put_rl(struct request_list *rl)
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{
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/* root_rl may not have blkg set */
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if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
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blkg_put(rl->blkg);
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}
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/**
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* blk_rq_set_rl - associate a request with a request_list
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* @rq: request of interest
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* @rl: target request_list
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*
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* Associate @rq with @rl so that accounting and freeing can know the
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* request_list @rq came from.
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*/
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static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
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{
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rq->rl = rl;
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}
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/**
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* blk_rq_rl - return the request_list a request came from
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* @rq: request of interest
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*
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* Return the request_list @rq is allocated from.
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*/
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static inline struct request_list *blk_rq_rl(struct request *rq)
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{
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return rq->rl;
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}
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struct request_list *__blk_queue_next_rl(struct request_list *rl,
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struct request_queue *q);
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/**
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* blk_queue_for_each_rl - iterate through all request_lists of a request_queue
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*
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* Should be used under queue_lock.
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*/
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#define blk_queue_for_each_rl(rl, q) \
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for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
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/**
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* blkg_stat_add - add a value to a blkg_stat
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* @stat: target blkg_stat
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* @val: value to add
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*
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* Add @val to @stat. The caller is responsible for synchronizing calls to
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* this function.
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*/
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static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
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{
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u64_stats_update_begin(&stat->syncp);
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stat->cnt += val;
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u64_stats_update_end(&stat->syncp);
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}
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/**
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* blkg_stat_read - read the current value of a blkg_stat
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* @stat: blkg_stat to read
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*
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* Read the current value of @stat. This function can be called without
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* synchroniztion and takes care of u64 atomicity.
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*/
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static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
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{
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unsigned int start;
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uint64_t v;
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do {
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start = u64_stats_fetch_begin(&stat->syncp);
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v = stat->cnt;
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} while (u64_stats_fetch_retry(&stat->syncp, start));
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return v;
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}
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/**
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* blkg_stat_reset - reset a blkg_stat
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* @stat: blkg_stat to reset
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*/
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static inline void blkg_stat_reset(struct blkg_stat *stat)
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{
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stat->cnt = 0;
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}
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/**
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* blkg_stat_merge - merge a blkg_stat into another
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* @to: the destination blkg_stat
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* @from: the source
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*
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* Add @from's count to @to.
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*/
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static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
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{
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blkg_stat_add(to, blkg_stat_read(from));
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}
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/**
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* blkg_rwstat_add - add a value to a blkg_rwstat
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* @rwstat: target blkg_rwstat
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* @rw: mask of REQ_{WRITE|SYNC}
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* @val: value to add
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*
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* Add @val to @rwstat. The counters are chosen according to @rw. The
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|
* caller is responsible for synchronizing calls to this function.
|
|
*/
|
|
static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
|
|
int rw, uint64_t val)
|
|
{
|
|
u64_stats_update_begin(&rwstat->syncp);
|
|
|
|
if (rw & REQ_WRITE)
|
|
rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
|
|
else
|
|
rwstat->cnt[BLKG_RWSTAT_READ] += val;
|
|
if (rw & REQ_SYNC)
|
|
rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
|
|
else
|
|
rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
|
|
|
|
u64_stats_update_end(&rwstat->syncp);
|
|
}
|
|
|
|
/**
|
|
* blkg_rwstat_read - read the current values of a blkg_rwstat
|
|
* @rwstat: blkg_rwstat to read
|
|
*
|
|
* Read the current snapshot of @rwstat and return it as the return value.
|
|
* This function can be called without synchronization and takes care of
|
|
* u64 atomicity.
|
|
*/
|
|
static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
|
|
{
|
|
unsigned int start;
|
|
struct blkg_rwstat tmp;
|
|
|
|
do {
|
|
start = u64_stats_fetch_begin(&rwstat->syncp);
|
|
tmp = *rwstat;
|
|
} while (u64_stats_fetch_retry(&rwstat->syncp, start));
|
|
|
|
return tmp;
|
|
}
|
|
|
|
/**
|
|
* blkg_rwstat_total - read the total count of a blkg_rwstat
|
|
* @rwstat: blkg_rwstat to read
|
|
*
|
|
* Return the total count of @rwstat regardless of the IO direction. This
|
|
* function can be called without synchronization and takes care of u64
|
|
* atomicity.
|
|
*/
|
|
static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
|
|
{
|
|
struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
|
|
|
|
return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
|
|
}
|
|
|
|
/**
|
|
* blkg_rwstat_reset - reset a blkg_rwstat
|
|
* @rwstat: blkg_rwstat to reset
|
|
*/
|
|
static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
|
|
{
|
|
memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
|
|
}
|
|
|
|
/**
|
|
* blkg_rwstat_merge - merge a blkg_rwstat into another
|
|
* @to: the destination blkg_rwstat
|
|
* @from: the source
|
|
*
|
|
* Add @from's counts to @to.
|
|
*/
|
|
static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
|
|
struct blkg_rwstat *from)
|
|
{
|
|
struct blkg_rwstat v = blkg_rwstat_read(from);
|
|
int i;
|
|
|
|
u64_stats_update_begin(&to->syncp);
|
|
for (i = 0; i < BLKG_RWSTAT_NR; i++)
|
|
to->cnt[i] += v.cnt[i];
|
|
u64_stats_update_end(&to->syncp);
|
|
}
|
|
|
|
#else /* CONFIG_BLK_CGROUP */
|
|
|
|
struct cgroup;
|
|
struct blkcg;
|
|
|
|
struct blkg_policy_data {
|
|
};
|
|
|
|
struct blkcg_gq {
|
|
};
|
|
|
|
struct blkcg_policy {
|
|
};
|
|
|
|
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
|
|
static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
|
|
static inline void blkcg_drain_queue(struct request_queue *q) { }
|
|
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 *cgroup_to_blkcg(struct cgroup *cgroup) { 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 struct request_list *blk_get_rl(struct request_queue *q,
|
|
struct bio *bio) { return &q->root_rl; }
|
|
static inline void blk_put_rl(struct request_list *rl) { }
|
|
static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
|
|
static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
|
|
|
|
#define blk_queue_for_each_rl(rl, q) \
|
|
for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
|
|
|
|
#endif /* CONFIG_BLK_CGROUP */
|
|
#endif /* _BLK_CGROUP_H */
|