/* SPDX-License-Identifier: GPL-2.0 */ #ifndef BLK_THROTTLE_H #define BLK_THROTTLE_H #include "blk-cgroup-rwstat.h" /* * To implement hierarchical throttling, throtl_grps form a tree and bios * are dispatched upwards level by level until they reach the top and get * issued. When dispatching bios from the children and local group at each * level, if the bios are dispatched into a single bio_list, there's a risk * of a local or child group which can queue many bios at once filling up * the list starving others. * * To avoid such starvation, dispatched bios are queued separately * according to where they came from. When they are again dispatched to * the parent, they're popped in round-robin order so that no single source * hogs the dispatch window. * * throtl_qnode is used to keep the queued bios separated by their sources. * Bios are queued to throtl_qnode which in turn is queued to * throtl_service_queue and then dispatched in round-robin order. * * It's also used to track the reference counts on blkg's. A qnode always * belongs to a throtl_grp and gets queued on itself or the parent, so * incrementing the reference of the associated throtl_grp when a qnode is * queued and decrementing when dequeued is enough to keep the whole blkg * tree pinned while bios are in flight. */ struct throtl_qnode { struct list_head node; /* service_queue->queued[] */ struct bio_list bios_bps; /* queued bios for bps limit */ struct bio_list bios_iops; /* queued bios for iops limit */ struct throtl_grp *tg; /* tg this qnode belongs to */ }; struct throtl_service_queue { struct throtl_service_queue *parent_sq; /* the parent service_queue */ /* * Bios queued directly to this service_queue or dispatched from * children throtl_grp's. */ struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */ unsigned int nr_queued_bps[2]; /* number of queued bps bios */ unsigned int nr_queued_iops[2]; /* number of queued iops bios */ /* * RB tree of active children throtl_grp's, which are sorted by * their ->disptime. */ struct rb_root_cached pending_tree; /* RB tree of active tgs */ unsigned int nr_pending; /* # queued in the tree */ unsigned long first_pending_disptime; /* disptime of the first tg */ struct timer_list pending_timer; /* fires on first_pending_disptime */ }; enum tg_state_flags { THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */ THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */ /* * The sq's iops queue is empty, and a bio is about to be enqueued * to the first qnode's bios_iops list. */ THROTL_TG_IOPS_WAS_EMPTY = 1 << 2, THROTL_TG_CANCELING = 1 << 3, /* starts to cancel bio */ }; struct throtl_grp { /* must be the first member */ struct blkg_policy_data pd; /* active throtl group service_queue member */ struct rb_node rb_node; /* throtl_data this group belongs to */ struct throtl_data *td; /* this group's service queue */ struct throtl_service_queue service_queue; /* * qnode_on_self is used when bios are directly queued to this * throtl_grp so that local bios compete fairly with bios * dispatched from children. qnode_on_parent is used when bios are * dispatched from this throtl_grp into its parent and will compete * with the sibling qnode_on_parents and the parent's * qnode_on_self. */ struct throtl_qnode qnode_on_self[2]; struct throtl_qnode qnode_on_parent[2]; /* * Dispatch time in jiffies. This is the estimated time when group * will unthrottle and is ready to dispatch more bio. It is used as * key to sort active groups in service tree. */ unsigned long disptime; unsigned int flags; /* are there any throtl rules between this group and td? */ bool has_rules_bps[2]; bool has_rules_iops[2]; /* bytes per second rate limits */ uint64_t bps[2]; /* IOPS limits */ unsigned int iops[2]; /* * Number of bytes/bio's dispatched in current slice. * When new configuration is submitted while some bios are still throttled, * first calculate the carryover: the amount of bytes/IOs already waited * under the previous configuration. Then, [bytes/io]_disp are represented * as the negative of the carryover, and they will be used to calculate the * wait time under the new configuration. */ int64_t bytes_disp[2]; int io_disp[2]; unsigned long last_check_time; /* When did we start a new slice */ unsigned long slice_start[2]; unsigned long slice_end[2]; struct blkg_rwstat stat_bytes; struct blkg_rwstat stat_ios; }; extern struct blkcg_policy blkcg_policy_throtl; static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) { return pd ? container_of(pd, struct throtl_grp, pd) : NULL; } static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) { return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); } /* * Internal throttling interface */ #ifndef CONFIG_BLK_DEV_THROTTLING static inline void blk_throtl_exit(struct gendisk *disk) { } static inline bool blk_throtl_bio(struct bio *bio) { return false; } static inline void blk_throtl_cancel_bios(struct gendisk *disk) { } #else /* CONFIG_BLK_DEV_THROTTLING */ void blk_throtl_exit(struct gendisk *disk); bool __blk_throtl_bio(struct bio *bio); void blk_throtl_cancel_bios(struct gendisk *disk); static inline bool blk_throtl_activated(struct request_queue *q) { /* * q->td guarantees that the blk-throttle module is already loaded, * and the plid of blk-throttle is assigned. * blkcg_policy_enabled() guarantees that the policy is activated * in the request_queue. */ return q->td != NULL && blkcg_policy_enabled(q, &blkcg_policy_throtl); } static inline bool blk_should_throtl(struct bio *bio) { struct throtl_grp *tg; int rw = bio_data_dir(bio); if (!blk_throtl_activated(bio->bi_bdev->bd_queue)) return false; tg = blkg_to_tg(bio->bi_blkg); if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) { if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { bio_set_flag(bio, BIO_CGROUP_ACCT); blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf, bio->bi_iter.bi_size); } blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1); } /* iops limit is always counted */ if (tg->has_rules_iops[rw]) return true; if (tg->has_rules_bps[rw] && !bio_flagged(bio, BIO_BPS_THROTTLED)) return true; return false; } static inline bool blk_throtl_bio(struct bio *bio) { /* * block throttling takes effect if the policy is activated * in the bio's request_queue. */ if (!blk_should_throtl(bio)) return false; return __blk_throtl_bio(bio); } #endif /* CONFIG_BLK_DEV_THROTTLING */ #endif
