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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _BLK_CGROUP_PRIVATE_H
3#define _BLK_CGROUP_PRIVATE_H
4/*
5 * block cgroup private header
6 *
7 * Based on ideas and code from CFQ, CFS and BFQ:
8 * Copyright (C) 2003 Jens Axboe <[email protected]>
9 *
10 * Copyright (C) 2008 Fabio Checconi <[email protected]>
11 * Paolo Valente <[email protected]>
12 *
13 * Copyright (C) 2009 Vivek Goyal <[email protected]>
14 * Nauman Rafique <[email protected]>
15 */
16
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>
22#include "blk.h"
23
24struct blkcg_gq;
25struct blkg_policy_data;
26
27
28/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
29#define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
30
31#ifdef CONFIG_BLK_CGROUP
32
33enum blkg_iostat_type {
34 BLKG_IOSTAT_READ,
35 BLKG_IOSTAT_WRITE,
36 BLKG_IOSTAT_DISCARD,
37
38 BLKG_IOSTAT_NR,
39};
40
41struct blkg_iostat {
42 u64 bytes[BLKG_IOSTAT_NR];
43 u64 ios[BLKG_IOSTAT_NR];
44};
45
46struct 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;
53};
54
55/* association between a blk cgroup and a request queue */
56struct blkcg_gq {
57 /* Pointer to the associated request_queue */
58 struct request_queue *q;
59 struct list_head q_node;
60 struct hlist_node blkcg_node;
61 struct blkcg *blkcg;
62
63 /* all non-root blkcg_gq's are guaranteed to have access to parent */
64 struct blkcg_gq *parent;
65
66 /* reference count */
67 struct percpu_ref refcnt;
68
69 /* is this blkg online? protected by both blkcg and q locks */
70 bool online;
71
72 struct blkg_iostat_set __percpu *iostat_cpu;
73 struct blkg_iostat_set iostat;
74
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;
79#endif
80 union {
81 struct work_struct async_bio_work;
82 struct work_struct free_work;
83 };
84
85 atomic_t use_delay;
86 atomic64_t delay_nsec;
87 atomic64_t delay_start;
88 u64 last_delay;
89 int last_use;
90
91 struct rcu_head rcu_head;
92};
93
94struct blkcg {
95 struct cgroup_subsys_state css;
96 spinlock_t lock;
97 refcount_t online_pin;
98 /* If there is block congestion on this cgroup. */
99 atomic_t congestion_count;
100
101 struct radix_tree_root blkg_tree;
102 struct blkcg_gq __rcu *blkg_hint;
103 struct hlist_head blkg_list;
104
105 struct blkcg_policy_data *cpd[BLKCG_MAX_POLS];
106
107 struct list_head all_blkcgs_node;
108
109 /*
110 * List of updated percpu blkg_iostat_set's since the last flush.
111 */
112 struct llist_head __percpu *lhead;
113
114#ifdef CONFIG_BLK_CGROUP_FC_APPID
115 char fc_app_id[FC_APPID_LEN];
116#endif
117#ifdef CONFIG_CGROUP_WRITEBACK
118 struct list_head cgwb_list;
119#endif
120};
121
122static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
123{
124 return css ? container_of(css, struct blkcg, css) : NULL;
125}
126
127/*
128 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
129 * request_queue (q). This is used by blkcg policies which need to track
130 * information per blkcg - q pair.
131 *
132 * There can be multiple active blkcg policies and each blkg:policy pair is
133 * represented by a blkg_policy_data which is allocated and freed by each
134 * policy's pd_alloc/free_fn() methods. A policy can allocate private data
135 * area by allocating larger data structure which embeds blkg_policy_data
136 * at the beginning.
137 */
138struct blkg_policy_data {
139 /* the blkg and policy id this per-policy data belongs to */
140 struct blkcg_gq *blkg;
141 int plid;
142 bool online;
143
144 struct rcu_head rcu_head;
145};
146
147/*
148 * Policies that need to keep per-blkcg data which is independent from any
149 * request_queue associated to it should implement cpd_alloc/free_fn()
150 * methods. A policy can allocate private data area by allocating larger
151 * data structure which embeds blkcg_policy_data at the beginning.
152 * cpd_init() is invoked to let each policy handle per-blkcg data.
153 */
154struct blkcg_policy_data {
155 /* the blkcg and policy id this per-policy data belongs to */
156 struct blkcg *blkcg;
157 int plid;
158};
159
160typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
161typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
162typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
163typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
164typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(struct gendisk *disk,
165 struct blkcg *blkcg, gfp_t gfp);
166typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
167typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
168typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
169typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
170typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
171typedef void (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd,
172 struct seq_file *s);
173
174struct blkcg_policy {
175 int plid;
176 /* cgroup files for the policy */
177 struct cftype *dfl_cftypes;
178 struct cftype *legacy_cftypes;
179
180 /* operations */
181 blkcg_pol_alloc_cpd_fn *cpd_alloc_fn;
182 blkcg_pol_free_cpd_fn *cpd_free_fn;
183
184 blkcg_pol_alloc_pd_fn *pd_alloc_fn;
185 blkcg_pol_init_pd_fn *pd_init_fn;
186 blkcg_pol_online_pd_fn *pd_online_fn;
187 blkcg_pol_offline_pd_fn *pd_offline_fn;
188 blkcg_pol_free_pd_fn *pd_free_fn;
189 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
190 blkcg_pol_stat_pd_fn *pd_stat_fn;
191};
192
193extern struct blkcg blkcg_root;
194extern bool blkcg_debug_stats;
195
196void blkg_init_queue(struct request_queue *q);
197int blkcg_init_disk(struct gendisk *disk);
198void blkcg_exit_disk(struct gendisk *disk);
199
200/* Blkio controller policy registration */
201int blkcg_policy_register(struct blkcg_policy *pol);
202void blkcg_policy_unregister(struct blkcg_policy *pol);
203int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol);
204void blkcg_deactivate_policy(struct gendisk *disk,
205 const struct blkcg_policy *pol);
206
207const char *blkg_dev_name(struct blkcg_gq *blkg);
208void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
209 u64 (*prfill)(struct seq_file *,
210 struct blkg_policy_data *, int),
211 const struct blkcg_policy *pol, int data,
212 bool show_total);
213u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
214
215struct blkg_conf_ctx {
216 char *input;
217 char *body;
218 struct block_device *bdev;
219 struct blkcg_gq *blkg;
220};
221
222void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
223int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
224 __cond_acquires(0, &ctx->bdev->bd_queue->rq_qos_mutex);
225int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
226 struct blkg_conf_ctx *ctx)
227 __cond_acquires(0, &ctx->bdev->bd_disk->queue->queue_lock);
228void blkg_conf_unprep(struct blkg_conf_ctx *ctx)
229 __releases(ctx->bdev->bd_disk->queue->queue_lock);
230void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx)
231 __releases(&ctx->bdev->bd_queue->rq_qos_mutex);
232
233/**
234 * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
235 * @bio: the target &bio
236 *
237 * Return: true if this bio needs to be submitted with the root blkg context.
238 *
239 * In order to avoid priority inversions we sometimes need to issue a bio as if
240 * it were attached to the root blkg, and then backcharge to the actual owning
241 * blkg. The idea is we do bio_blkcg_css() to look up the actual context for
242 * the bio and attach the appropriate blkg to the bio. Then we call this helper
243 * and if it is true run with the root blkg for that queue and then do any
244 * backcharging to the originating cgroup once the io is complete.
245 */
246static inline bool bio_issue_as_root_blkg(struct bio *bio)
247{
248 return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
249}
250
251/**
252 * blkg_lookup - lookup blkg for the specified blkcg - q pair
253 * @blkcg: blkcg of interest
254 * @q: request_queue of interest
255 *
256 * Lookup blkg for the @blkcg - @q pair.
257 *
258 * Must be called in a RCU critical section.
259 */
260static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
261 struct request_queue *q)
262{
263 struct blkcg_gq *blkg;
264
265 if (blkcg == &blkcg_root)
266 return q->root_blkg;
267
268 blkg = rcu_dereference_check(blkcg->blkg_hint,
269 lockdep_is_held(&q->queue_lock));
270 if (blkg && blkg->q == q)
271 return blkg;
272
273 blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
274 if (blkg && blkg->q != q)
275 blkg = NULL;
276 return blkg;
277}
278
279/**
280 * blkg_to_pd - get policy private data
281 * @blkg: blkg of interest
282 * @pol: policy of interest
283 *
284 * Return pointer to private data associated with the @blkg-@pol pair.
285 */
286static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
287 const struct blkcg_policy *pol)
288{
289 return blkg ? READ_ONCE(blkg->pd[pol->plid]) : NULL;
290}
291
292static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
293 struct blkcg_policy *pol)
294{
295 return blkcg ? blkcg->cpd[pol->plid] : NULL;
296}
297
298/**
299 * pd_to_blkg - get blkg associated with policy private data
300 * @pd: policy private data of interest
301 *
302 * @pd is policy private data. Determine the blkg it's associated with.
303 */
304static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
305{
306 return pd ? pd->blkg : NULL;
307}
308
309static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
310{
311 return cpd ? cpd->blkcg : NULL;
312}
313
314/**
315 * blkg_get - get a blkg reference
316 * @blkg: blkg to get
317 *
318 * The caller should be holding an existing reference.
319 */
320static inline void blkg_get(struct blkcg_gq *blkg)
321{
322 percpu_ref_get(&blkg->refcnt);
323}
324
325/**
326 * blkg_tryget - try and get a blkg reference
327 * @blkg: blkg to get
328 *
329 * This is for use when doing an RCU lookup of the blkg. We may be in the midst
330 * of freeing this blkg, so we can only use it if the refcnt is not zero.
331 */
332static inline bool blkg_tryget(struct blkcg_gq *blkg)
333{
334 return blkg && percpu_ref_tryget(&blkg->refcnt);
335}
336
337/**
338 * blkg_put - put a blkg reference
339 * @blkg: blkg to put
340 */
341static inline void blkg_put(struct blkcg_gq *blkg)
342{
343 percpu_ref_put(&blkg->refcnt);
344}
345
346/**
347 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
348 * @d_blkg: loop cursor pointing to the current descendant
349 * @pos_css: used for iteration
350 * @p_blkg: target blkg to walk descendants of
351 *
352 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
353 * read locked. If called under either blkcg or queue lock, the iteration
354 * is guaranteed to include all and only online blkgs. The caller may
355 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
356 * @p_blkg is included in the iteration and the first node to be visited.
357 */
358#define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
359 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
360 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
361 (p_blkg)->q)))
362
363/**
364 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
365 * @d_blkg: loop cursor pointing to the current descendant
366 * @pos_css: used for iteration
367 * @p_blkg: target blkg to walk descendants of
368 *
369 * Similar to blkg_for_each_descendant_pre() but performs post-order
370 * traversal instead. Synchronization rules are the same. @p_blkg is
371 * included in the iteration and the last node to be visited.
372 */
373#define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
374 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
375 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
376 (p_blkg)->q)))
377
378/*
379 * blkcg_nr_congested gates the hierarchy walk in blk_cgroup_congested().
380 * These two helpers keep it in step with each blkcg's congestion_count in
381 * normal operation; blkcg_css_free() drops a residual count as a backstop.
382 */
383static inline void blkcg_inc_congestion_count(struct blkcg *blkcg)
384{
385 if (atomic_inc_return(&blkcg->congestion_count) == 1)
386 atomic_inc(&blkcg_nr_congested);
387}
388
389static inline void blkcg_dec_congestion_count(struct blkcg *blkcg)
390{
391 if (atomic_dec_and_test(&blkcg->congestion_count))
392 atomic_dec(&blkcg_nr_congested);
393}
394
395static inline void blkcg_use_delay(struct blkcg_gq *blkg)
396{
397 if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
398 return;
399 if (atomic_add_return(1, &blkg->use_delay) == 1)
400 blkcg_inc_congestion_count(blkg->blkcg);
401}
402
403static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
404{
405 int old = atomic_read(&blkg->use_delay);
406
407 if (WARN_ON_ONCE(old < 0))
408 return 0;
409 if (old == 0)
410 return 0;
411
412 /*
413 * We do this song and dance because we can race with somebody else
414 * adding or removing delay. If we just did an atomic_dec we'd end up
415 * negative and we'd already be in trouble. We need to subtract 1 and
416 * then check to see if we were the last delay so we can drop the
417 * congestion count on the cgroup.
418 */
419 while (old && !atomic_try_cmpxchg(&blkg->use_delay, &old, old - 1))
420 ;
421
422 if (old == 0)
423 return 0;
424 if (old == 1)
425 blkcg_dec_congestion_count(blkg->blkcg);
426 return 1;
427}
428
429/**
430 * blkcg_set_delay - Enable allocator delay mechanism with the specified delay amount
431 * @blkg: target blkg
432 * @delay: delay duration in nsecs
433 *
434 * When enabled with this function, the delay is not decayed and must be
435 * explicitly cleared with blkcg_clear_delay(). Must not be mixed with
436 * blkcg_[un]use_delay() and blkcg_add_delay() usages.
437 */
438static inline void blkcg_set_delay(struct blkcg_gq *blkg, u64 delay)
439{
440 int old = atomic_read(&blkg->use_delay);
441
442 /* We only want 1 person setting the congestion count for this blkg. */
443 if (!old && atomic_try_cmpxchg(&blkg->use_delay, &old, -1))
444 blkcg_inc_congestion_count(blkg->blkcg);
445
446 atomic64_set(&blkg->delay_nsec, delay);
447}
448
449/**
450 * blkcg_clear_delay - Disable allocator delay mechanism
451 * @blkg: target blkg
452 *
453 * Disable use_delay mechanism. See blkcg_set_delay().
454 */
455static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
456{
457 int old = atomic_read(&blkg->use_delay);
458
459 /* We only want 1 person clearing the congestion count for this blkg. */
460 if (old && atomic_try_cmpxchg(&blkg->use_delay, &old, 0))
461 blkcg_dec_congestion_count(blkg->blkcg);
462}
463
464/**
465 * blk_cgroup_mergeable - Determine whether to allow or disallow merges
466 * @rq: request to merge into
467 * @bio: bio to merge
468 *
469 * @bio and @rq should belong to the same cgroup and their issue_as_root should
470 * match. The latter is necessary as we don't want to throttle e.g. a metadata
471 * update because it happens to be next to a regular IO.
472 */
473static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio)
474{
475 return rq->bio->bi_blkg == bio->bi_blkg &&
476 bio_issue_as_root_blkg(rq->bio) == bio_issue_as_root_blkg(bio);
477}
478
479static inline bool blkcg_policy_enabled(struct request_queue *q,
480 const struct blkcg_policy *pol)
481{
482 return pol && test_bit(pol->plid, q->blkcg_pols);
483}
484
485void blk_cgroup_bio_start(struct bio *bio);
486void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
487#else /* CONFIG_BLK_CGROUP */
488
489struct blkg_policy_data {
490};
491
492struct blkcg_policy_data {
493};
494
495struct blkcg_policy {
496};
497
498struct blkcg {
499};
500
501static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
502static inline void blkg_init_queue(struct request_queue *q) { }
503static inline int blkcg_init_disk(struct gendisk *disk) { return 0; }
504static inline void blkcg_exit_disk(struct gendisk *disk) { }
505static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
506static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
507static inline int blkcg_activate_policy(struct gendisk *disk,
508 const struct blkcg_policy *pol) { return 0; }
509static inline void blkcg_deactivate_policy(struct gendisk *disk,
510 const struct blkcg_policy *pol) { }
511
512static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
513 const struct blkcg_policy *pol) { return NULL; }
514static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
515static inline void blkg_get(struct blkcg_gq *blkg) { }
516static inline void blkg_put(struct blkcg_gq *blkg) { }
517static inline void blk_cgroup_bio_start(struct bio *bio) { }
518static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) { return true; }
519
520#define blk_queue_for_each_rl(rl, q) \
521 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
522
523#endif /* CONFIG_BLK_CGROUP */
524
525#endif /* _BLK_CGROUP_PRIVATE_H */