1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _BLK_CGROUP_PRIVATE_H
3 #define _BLK_CGROUP_PRIVATE_H
5 * block cgroup private header
7 * Based on ideas and code from CFQ, CFS and BFQ:
8 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
10 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
11 * Paolo Valente <paolo.valente@unimore.it>
13 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
14 * Nauman Rafique <nauman@google.com>
17 #include <linux/blk-cgroup.h>
18 #include <linux/cgroup.h>
19 #include <linux/kthread.h>
20 #include <linux/blk-mq.h>
21 #include <linux/llist.h>
25 struct blkg_policy_data;
28 /* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
29 #define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
31 #ifdef CONFIG_BLK_CGROUP
33 enum blkg_iostat_type {
42 u64 bytes[BLKG_IOSTAT_NR];
43 u64 ios[BLKG_IOSTAT_NR];
46 struct blkg_iostat_set {
47 struct u64_stats_sync sync;
48 struct blkcg_gq *blkg;
49 struct llist_node lnode;
50 int lqueued; /* queued in llist */
51 struct blkg_iostat cur;
52 struct blkg_iostat last;
55 /* association between a blk cgroup and a request queue */
57 /* Pointer to the associated request_queue */
58 struct request_queue *q;
59 struct list_head q_node;
60 struct hlist_node blkcg_node;
63 /* all non-root blkcg_gq's are guaranteed to have access to parent */
64 struct blkcg_gq *parent;
67 struct percpu_ref refcnt;
69 /* is this blkg online? protected by both blkcg and q locks */
72 struct blkg_iostat_set __percpu *iostat_cpu;
73 struct blkg_iostat_set iostat;
75 struct blkg_policy_data *pd[BLKCG_MAX_POLS];
76 #ifdef CONFIG_BLK_CGROUP_PUNT_BIO
77 spinlock_t async_bio_lock;
78 struct bio_list async_bios;
81 struct work_struct async_bio_work;
82 struct work_struct free_work;
86 atomic64_t delay_nsec;
87 atomic64_t delay_start;
91 struct rcu_head rcu_head;
95 struct cgroup_subsys_state css;
97 refcount_t online_pin;
99 struct radix_tree_root blkg_tree;
100 struct blkcg_gq __rcu *blkg_hint;
101 struct hlist_head blkg_list;
103 struct blkcg_policy_data *cpd[BLKCG_MAX_POLS];
105 struct list_head all_blkcgs_node;
108 * List of updated percpu blkg_iostat_set's since the last flush.
110 struct llist_head __percpu *lhead;
112 #ifdef CONFIG_BLK_CGROUP_FC_APPID
113 char fc_app_id[FC_APPID_LEN];
115 #ifdef CONFIG_CGROUP_WRITEBACK
116 struct list_head cgwb_list;
120 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
122 return css ? container_of(css, struct blkcg, css) : NULL;
126 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
127 * request_queue (q). This is used by blkcg policies which need to track
128 * information per blkcg - q pair.
130 * There can be multiple active blkcg policies and each blkg:policy pair is
131 * represented by a blkg_policy_data which is allocated and freed by each
132 * policy's pd_alloc/free_fn() methods. A policy can allocate private data
133 * area by allocating larger data structure which embeds blkg_policy_data
136 struct blkg_policy_data {
137 /* the blkg and policy id this per-policy data belongs to */
138 struct blkcg_gq *blkg;
144 * Policies that need to keep per-blkcg data which is independent from any
145 * request_queue associated to it should implement cpd_alloc/free_fn()
146 * methods. A policy can allocate private data area by allocating larger
147 * data structure which embeds blkcg_policy_data at the beginning.
148 * cpd_init() is invoked to let each policy handle per-blkcg data.
150 struct blkcg_policy_data {
151 /* the blkcg and policy id this per-policy data belongs to */
156 typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
157 typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
158 typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
159 typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
160 typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(struct gendisk *disk,
161 struct blkcg *blkcg, gfp_t gfp);
162 typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
163 typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
164 typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
165 typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
166 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
167 typedef void (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd,
170 struct blkcg_policy {
172 /* cgroup files for the policy */
173 struct cftype *dfl_cftypes;
174 struct cftype *legacy_cftypes;
177 blkcg_pol_alloc_cpd_fn *cpd_alloc_fn;
178 blkcg_pol_free_cpd_fn *cpd_free_fn;
180 blkcg_pol_alloc_pd_fn *pd_alloc_fn;
181 blkcg_pol_init_pd_fn *pd_init_fn;
182 blkcg_pol_online_pd_fn *pd_online_fn;
183 blkcg_pol_offline_pd_fn *pd_offline_fn;
184 blkcg_pol_free_pd_fn *pd_free_fn;
185 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
186 blkcg_pol_stat_pd_fn *pd_stat_fn;
189 extern struct blkcg blkcg_root;
190 extern bool blkcg_debug_stats;
192 void blkg_init_queue(struct request_queue *q);
193 int blkcg_init_disk(struct gendisk *disk);
194 void blkcg_exit_disk(struct gendisk *disk);
196 /* Blkio controller policy registration */
197 int blkcg_policy_register(struct blkcg_policy *pol);
198 void blkcg_policy_unregister(struct blkcg_policy *pol);
199 int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol);
200 void blkcg_deactivate_policy(struct gendisk *disk,
201 const struct blkcg_policy *pol);
203 const char *blkg_dev_name(struct blkcg_gq *blkg);
204 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
205 u64 (*prfill)(struct seq_file *,
206 struct blkg_policy_data *, int),
207 const struct blkcg_policy *pol, int data,
209 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
211 struct blkg_conf_ctx {
214 struct block_device *bdev;
215 struct blkcg_gq *blkg;
218 void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
219 int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx);
220 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
221 struct blkg_conf_ctx *ctx);
222 void blkg_conf_exit(struct blkg_conf_ctx *ctx);
225 * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
226 * @return: true if this bio needs to be submitted with the root blkg context.
228 * In order to avoid priority inversions we sometimes need to issue a bio as if
229 * it were attached to the root blkg, and then backcharge to the actual owning
230 * blkg. The idea is we do bio_blkcg_css() to look up the actual context for
231 * the bio and attach the appropriate blkg to the bio. Then we call this helper
232 * and if it is true run with the root blkg for that queue and then do any
233 * backcharging to the originating cgroup once the io is complete.
235 static inline bool bio_issue_as_root_blkg(struct bio *bio)
237 return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
241 * blkg_lookup - lookup blkg for the specified blkcg - q pair
242 * @blkcg: blkcg of interest
243 * @q: request_queue of interest
245 * Lookup blkg for the @blkcg - @q pair.
247 * Must be called in a RCU critical section.
249 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
250 struct request_queue *q)
252 struct blkcg_gq *blkg;
254 if (blkcg == &blkcg_root)
257 blkg = rcu_dereference_check(blkcg->blkg_hint,
258 lockdep_is_held(&q->queue_lock));
259 if (blkg && blkg->q == q)
262 blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
263 if (blkg && blkg->q != q)
269 * blkg_to_pdata - get policy private data
270 * @blkg: blkg of interest
271 * @pol: policy of interest
273 * Return pointer to private data associated with the @blkg-@pol pair.
275 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
276 struct blkcg_policy *pol)
278 return blkg ? blkg->pd[pol->plid] : NULL;
281 static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
282 struct blkcg_policy *pol)
284 return blkcg ? blkcg->cpd[pol->plid] : NULL;
288 * pdata_to_blkg - get blkg associated with policy private data
289 * @pd: policy private data of interest
291 * @pd is policy private data. Determine the blkg it's associated with.
293 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
295 return pd ? pd->blkg : NULL;
298 static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
300 return cpd ? cpd->blkcg : NULL;
304 * blkg_path - format cgroup path of blkg
305 * @blkg: blkg of interest
306 * @buf: target buffer
307 * @buflen: target buffer length
309 * Format the path of the cgroup of @blkg into @buf.
311 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
313 return cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
317 * blkg_get - get a blkg reference
320 * The caller should be holding an existing reference.
322 static inline void blkg_get(struct blkcg_gq *blkg)
324 percpu_ref_get(&blkg->refcnt);
328 * blkg_tryget - try and get a blkg reference
331 * This is for use when doing an RCU lookup of the blkg. We may be in the midst
332 * of freeing this blkg, so we can only use it if the refcnt is not zero.
334 static inline bool blkg_tryget(struct blkcg_gq *blkg)
336 return blkg && percpu_ref_tryget(&blkg->refcnt);
340 * blkg_put - put a blkg reference
343 static inline void blkg_put(struct blkcg_gq *blkg)
345 percpu_ref_put(&blkg->refcnt);
349 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
350 * @d_blkg: loop cursor pointing to the current descendant
351 * @pos_css: used for iteration
352 * @p_blkg: target blkg to walk descendants of
354 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
355 * read locked. If called under either blkcg or queue lock, the iteration
356 * is guaranteed to include all and only online blkgs. The caller may
357 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
358 * @p_blkg is included in the iteration and the first node to be visited.
360 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
361 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
362 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
366 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
367 * @d_blkg: loop cursor pointing to the current descendant
368 * @pos_css: used for iteration
369 * @p_blkg: target blkg to walk descendants of
371 * Similar to blkg_for_each_descendant_pre() but performs post-order
372 * traversal instead. Synchronization rules are the same. @p_blkg is
373 * included in the iteration and the last node to be visited.
375 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
376 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
377 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
380 static inline void blkcg_bio_issue_init(struct bio *bio)
382 bio_issue_init(&bio->bi_issue, bio_sectors(bio));
385 static inline void blkcg_use_delay(struct blkcg_gq *blkg)
387 if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
389 if (atomic_add_return(1, &blkg->use_delay) == 1)
390 atomic_inc(&blkg->blkcg->css.cgroup->congestion_count);
393 static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
395 int old = atomic_read(&blkg->use_delay);
397 if (WARN_ON_ONCE(old < 0))
403 * We do this song and dance because we can race with somebody else
404 * adding or removing delay. If we just did an atomic_dec we'd end up
405 * negative and we'd already be in trouble. We need to subtract 1 and
406 * then check to see if we were the last delay so we can drop the
407 * congestion count on the cgroup.
409 while (old && !atomic_try_cmpxchg(&blkg->use_delay, &old, old - 1))
415 atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
420 * blkcg_set_delay - Enable allocator delay mechanism with the specified delay amount
422 * @delay: delay duration in nsecs
424 * When enabled with this function, the delay is not decayed and must be
425 * explicitly cleared with blkcg_clear_delay(). Must not be mixed with
426 * blkcg_[un]use_delay() and blkcg_add_delay() usages.
428 static inline void blkcg_set_delay(struct blkcg_gq *blkg, u64 delay)
430 int old = atomic_read(&blkg->use_delay);
432 /* We only want 1 person setting the congestion count for this blkg. */
433 if (!old && atomic_try_cmpxchg(&blkg->use_delay, &old, -1))
434 atomic_inc(&blkg->blkcg->css.cgroup->congestion_count);
436 atomic64_set(&blkg->delay_nsec, delay);
440 * blkcg_clear_delay - Disable allocator delay mechanism
443 * Disable use_delay mechanism. See blkcg_set_delay().
445 static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
447 int old = atomic_read(&blkg->use_delay);
449 /* We only want 1 person clearing the congestion count for this blkg. */
450 if (old && atomic_try_cmpxchg(&blkg->use_delay, &old, 0))
451 atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
455 * blk_cgroup_mergeable - Determine whether to allow or disallow merges
456 * @rq: request to merge into
459 * @bio and @rq should belong to the same cgroup and their issue_as_root should
460 * match. The latter is necessary as we don't want to throttle e.g. a metadata
461 * update because it happens to be next to a regular IO.
463 static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio)
465 return rq->bio->bi_blkg == bio->bi_blkg &&
466 bio_issue_as_root_blkg(rq->bio) == bio_issue_as_root_blkg(bio);
469 void blk_cgroup_bio_start(struct bio *bio);
470 void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
471 #else /* CONFIG_BLK_CGROUP */
473 struct blkg_policy_data {
476 struct blkcg_policy_data {
479 struct blkcg_policy {
485 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
486 static inline void blkg_init_queue(struct request_queue *q) { }
487 static inline int blkcg_init_disk(struct gendisk *disk) { return 0; }
488 static inline void blkcg_exit_disk(struct gendisk *disk) { }
489 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
490 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
491 static inline int blkcg_activate_policy(struct gendisk *disk,
492 const struct blkcg_policy *pol) { return 0; }
493 static inline void blkcg_deactivate_policy(struct gendisk *disk,
494 const struct blkcg_policy *pol) { }
496 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
497 struct blkcg_policy *pol) { return NULL; }
498 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
499 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
500 static inline void blkg_get(struct blkcg_gq *blkg) { }
501 static inline void blkg_put(struct blkcg_gq *blkg) { }
502 static inline void blkcg_bio_issue_init(struct bio *bio) { }
503 static inline void blk_cgroup_bio_start(struct bio *bio) { }
504 static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) { return true; }
506 #define blk_queue_for_each_rl(rl, q) \
507 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
509 #endif /* CONFIG_BLK_CGROUP */
511 #endif /* _BLK_CGROUP_PRIVATE_H */