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 <axboe@kernel.dk>
9 *
10 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
11 * Paolo Valente <paolo.valente@unimore.it>
12 *
13 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
14 * Nauman Rafique <nauman@google.com>
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
23struct blkcg_gq;
24struct blkg_policy_data;
25
26
27/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
28#define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
29
30#ifdef CONFIG_BLK_CGROUP
31
32enum blkg_iostat_type {
33 BLKG_IOSTAT_READ,
34 BLKG_IOSTAT_WRITE,
35 BLKG_IOSTAT_DISCARD,
36
37 BLKG_IOSTAT_NR,
38};
39
40struct blkg_iostat {
41 u64 bytes[BLKG_IOSTAT_NR];
42 u64 ios[BLKG_IOSTAT_NR];
43};
44
45struct blkg_iostat_set {
46 struct u64_stats_sync sync;
47 struct blkcg_gq *blkg;
48 struct llist_node lnode;
49 int lqueued; /* queued in llist */
50 struct blkg_iostat cur;
51 struct blkg_iostat last;
52};
53
54/* association between a blk cgroup and a request queue */
55struct blkcg_gq {
56 /* Pointer to the associated request_queue */
57 struct request_queue *q;
58 struct list_head q_node;
59 struct hlist_node blkcg_node;
60 struct blkcg *blkcg;
61
62 /* all non-root blkcg_gq's are guaranteed to have access to parent */
63 struct blkcg_gq *parent;
64
65 /* reference count */
66 struct percpu_ref refcnt;
67
68 /* is this blkg online? protected by both blkcg and q locks */
69 bool online;
70
71 struct blkg_iostat_set __percpu *iostat_cpu;
72 struct blkg_iostat_set iostat;
73
74 struct blkg_policy_data *pd[BLKCG_MAX_POLS];
75#ifdef CONFIG_BLK_CGROUP_PUNT_BIO
76 spinlock_t async_bio_lock;
77 struct bio_list async_bios;
78#endif
79 union {
80 struct work_struct async_bio_work;
81 struct work_struct free_work;
82 };
83
84 atomic_t use_delay;
85 atomic64_t delay_nsec;
86 atomic64_t delay_start;
87 u64 last_delay;
88 int last_use;
89
90 struct rcu_head rcu_head;
91};
92
93struct blkcg {
94 struct cgroup_subsys_state css;
95 spinlock_t lock;
96 refcount_t online_pin;
97
98 struct radix_tree_root blkg_tree;
99 struct blkcg_gq __rcu *blkg_hint;
100 struct hlist_head blkg_list;
101
102 struct blkcg_policy_data *cpd[BLKCG_MAX_POLS];
103
104 struct list_head all_blkcgs_node;
105
106 /*
107 * List of updated percpu blkg_iostat_set's since the last flush.
108 */
109 struct llist_head __percpu *lhead;
110
111#ifdef CONFIG_BLK_CGROUP_FC_APPID
112 char fc_app_id[FC_APPID_LEN];
113#endif
114#ifdef CONFIG_CGROUP_WRITEBACK
115 struct list_head cgwb_list;
116#endif
117};
118
119static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
120{
121 return css ? container_of(css, struct blkcg, css) : NULL;
122}
123
124/*
125 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
126 * request_queue (q). This is used by blkcg policies which need to track
127 * information per blkcg - q pair.
128 *
129 * There can be multiple active blkcg policies and each blkg:policy pair is
130 * represented by a blkg_policy_data which is allocated and freed by each
131 * policy's pd_alloc/free_fn() methods. A policy can allocate private data
132 * area by allocating larger data structure which embeds blkg_policy_data
133 * at the beginning.
134 */
135struct blkg_policy_data {
136 /* the blkg and policy id this per-policy data belongs to */
137 struct blkcg_gq *blkg;
138 int plid;
139 bool online;
140};
141
142/*
143 * Policies that need to keep per-blkcg data which is independent from any
144 * request_queue associated to it should implement cpd_alloc/free_fn()
145 * methods. A policy can allocate private data area by allocating larger
146 * data structure which embeds blkcg_policy_data at the beginning.
147 * cpd_init() is invoked to let each policy handle per-blkcg data.
148 */
149struct blkcg_policy_data {
150 /* the blkcg and policy id this per-policy data belongs to */
151 struct blkcg *blkcg;
152 int plid;
153};
154
155typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
156typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
157typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
158typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
159typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(struct gendisk *disk,
160 struct blkcg *blkcg, gfp_t gfp);
161typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
162typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
163typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
164typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
165typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
166typedef void (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd,
167 struct seq_file *s);
168
169struct blkcg_policy {
170 int plid;
171 /* cgroup files for the policy */
172 struct cftype *dfl_cftypes;
173 struct cftype *legacy_cftypes;
174
175 /* operations */
176 blkcg_pol_alloc_cpd_fn *cpd_alloc_fn;
177 blkcg_pol_free_cpd_fn *cpd_free_fn;
178
179 blkcg_pol_alloc_pd_fn *pd_alloc_fn;
180 blkcg_pol_init_pd_fn *pd_init_fn;
181 blkcg_pol_online_pd_fn *pd_online_fn;
182 blkcg_pol_offline_pd_fn *pd_offline_fn;
183 blkcg_pol_free_pd_fn *pd_free_fn;
184 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
185 blkcg_pol_stat_pd_fn *pd_stat_fn;
186};
187
188extern struct blkcg blkcg_root;
189extern bool blkcg_debug_stats;
190
191int blkcg_init_disk(struct gendisk *disk);
192void blkcg_exit_disk(struct gendisk *disk);
193
194/* Blkio controller policy registration */
195int blkcg_policy_register(struct blkcg_policy *pol);
196void blkcg_policy_unregister(struct blkcg_policy *pol);
197int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol);
198void blkcg_deactivate_policy(struct gendisk *disk,
199 const struct blkcg_policy *pol);
200
201const char *blkg_dev_name(struct blkcg_gq *blkg);
202void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
203 u64 (*prfill)(struct seq_file *,
204 struct blkg_policy_data *, int),
205 const struct blkcg_policy *pol, int data,
206 bool show_total);
207u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
208
209struct blkg_conf_ctx {
210 char *input;
211 char *body;
212 struct block_device *bdev;
213 struct blkcg_gq *blkg;
214};
215
216void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
217int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx);
218int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
219 struct blkg_conf_ctx *ctx);
220void blkg_conf_exit(struct blkg_conf_ctx *ctx);
221
222/**
223 * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
224 * @return: true if this bio needs to be submitted with the root blkg context.
225 *
226 * In order to avoid priority inversions we sometimes need to issue a bio as if
227 * it were attached to the root blkg, and then backcharge to the actual owning
228 * blkg. The idea is we do bio_blkcg_css() to look up the actual context for
229 * the bio and attach the appropriate blkg to the bio. Then we call this helper
230 * and if it is true run with the root blkg for that queue and then do any
231 * backcharging to the originating cgroup once the io is complete.
232 */
233static inline bool bio_issue_as_root_blkg(struct bio *bio)
234{
235 return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
236}
237
238/**
239 * blkg_lookup - lookup blkg for the specified blkcg - q pair
240 * @blkcg: blkcg of interest
241 * @q: request_queue of interest
242 *
243 * Lookup blkg for the @blkcg - @q pair.
244
245 * Must be called in a RCU critical section.
246 */
247static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
248 struct request_queue *q)
249{
250 struct blkcg_gq *blkg;
251
252 WARN_ON_ONCE(!rcu_read_lock_held());
253
254 if (blkcg == &blkcg_root)
255 return q->root_blkg;
256
257 blkg = rcu_dereference(blkcg->blkg_hint);
258 if (blkg && blkg->q == q)
259 return blkg;
260
261 blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
262 if (blkg && blkg->q != q)
263 blkg = NULL;
264 return blkg;
265}
266
267/**
268 * blkg_to_pdata - get policy private data
269 * @blkg: blkg of interest
270 * @pol: policy of interest
271 *
272 * Return pointer to private data associated with the @blkg-@pol pair.
273 */
274static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
275 struct blkcg_policy *pol)
276{
277 return blkg ? blkg->pd[pol->plid] : NULL;
278}
279
280static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
281 struct blkcg_policy *pol)
282{
283 return blkcg ? blkcg->cpd[pol->plid] : NULL;
284}
285
286/**
287 * pdata_to_blkg - get blkg associated with policy private data
288 * @pd: policy private data of interest
289 *
290 * @pd is policy private data. Determine the blkg it's associated with.
291 */
292static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
293{
294 return pd ? pd->blkg : NULL;
295}
296
297static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
298{
299 return cpd ? cpd->blkcg : NULL;
300}
301
302/**
303 * blkg_path - format cgroup path of blkg
304 * @blkg: blkg of interest
305 * @buf: target buffer
306 * @buflen: target buffer length
307 *
308 * Format the path of the cgroup of @blkg into @buf.
309 */
310static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
311{
312 return cgroup_path(cgrp: blkg->blkcg->css.cgroup, buf, buflen);
313}
314
315/**
316 * blkg_get - get a blkg reference
317 * @blkg: blkg to get
318 *
319 * The caller should be holding an existing reference.
320 */
321static inline void blkg_get(struct blkcg_gq *blkg)
322{
323 percpu_ref_get(ref: &blkg->refcnt);
324}
325
326/**
327 * blkg_tryget - try and get a blkg reference
328 * @blkg: blkg to get
329 *
330 * This is for use when doing an RCU lookup of the blkg. We may be in the midst
331 * of freeing this blkg, so we can only use it if the refcnt is not zero.
332 */
333static inline bool blkg_tryget(struct blkcg_gq *blkg)
334{
335 return blkg && percpu_ref_tryget(ref: &blkg->refcnt);
336}
337
338/**
339 * blkg_put - put a blkg reference
340 * @blkg: blkg to put
341 */
342static inline void blkg_put(struct blkcg_gq *blkg)
343{
344 percpu_ref_put(ref: &blkg->refcnt);
345}
346
347/**
348 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
349 * @d_blkg: loop cursor pointing to the current descendant
350 * @pos_css: used for iteration
351 * @p_blkg: target blkg to walk descendants of
352 *
353 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
354 * read locked. If called under either blkcg or queue lock, the iteration
355 * is guaranteed to include all and only online blkgs. The caller may
356 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
357 * @p_blkg is included in the iteration and the first node to be visited.
358 */
359#define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
360 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
361 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
362 (p_blkg)->q)))
363
364/**
365 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
366 * @d_blkg: loop cursor pointing to the current descendant
367 * @pos_css: used for iteration
368 * @p_blkg: target blkg to walk descendants of
369 *
370 * Similar to blkg_for_each_descendant_pre() but performs post-order
371 * traversal instead. Synchronization rules are the same. @p_blkg is
372 * included in the iteration and the last node to be visited.
373 */
374#define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
375 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
376 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
377 (p_blkg)->q)))
378
379static inline void blkcg_bio_issue_init(struct bio *bio)
380{
381 bio_issue_init(issue: &bio->bi_issue, bio_sectors(bio));
382}
383
384static inline void blkcg_use_delay(struct blkcg_gq *blkg)
385{
386 if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
387 return;
388 if (atomic_add_return(i: 1, v: &blkg->use_delay) == 1)
389 atomic_inc(v: &blkg->blkcg->css.cgroup->congestion_count);
390}
391
392static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
393{
394 int old = atomic_read(v: &blkg->use_delay);
395
396 if (WARN_ON_ONCE(old < 0))
397 return 0;
398 if (old == 0)
399 return 0;
400
401 /*
402 * We do this song and dance because we can race with somebody else
403 * adding or removing delay. If we just did an atomic_dec we'd end up
404 * negative and we'd already be in trouble. We need to subtract 1 and
405 * then check to see if we were the last delay so we can drop the
406 * congestion count on the cgroup.
407 */
408 while (old && !atomic_try_cmpxchg(v: &blkg->use_delay, old: &old, new: old - 1))
409 ;
410
411 if (old == 0)
412 return 0;
413 if (old == 1)
414 atomic_dec(v: &blkg->blkcg->css.cgroup->congestion_count);
415 return 1;
416}
417
418/**
419 * blkcg_set_delay - Enable allocator delay mechanism with the specified delay amount
420 * @blkg: target blkg
421 * @delay: delay duration in nsecs
422 *
423 * When enabled with this function, the delay is not decayed and must be
424 * explicitly cleared with blkcg_clear_delay(). Must not be mixed with
425 * blkcg_[un]use_delay() and blkcg_add_delay() usages.
426 */
427static inline void blkcg_set_delay(struct blkcg_gq *blkg, u64 delay)
428{
429 int old = atomic_read(v: &blkg->use_delay);
430
431 /* We only want 1 person setting the congestion count for this blkg. */
432 if (!old && atomic_try_cmpxchg(v: &blkg->use_delay, old: &old, new: -1))
433 atomic_inc(v: &blkg->blkcg->css.cgroup->congestion_count);
434
435 atomic64_set(v: &blkg->delay_nsec, i: delay);
436}
437
438/**
439 * blkcg_clear_delay - Disable allocator delay mechanism
440 * @blkg: target blkg
441 *
442 * Disable use_delay mechanism. See blkcg_set_delay().
443 */
444static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
445{
446 int old = atomic_read(v: &blkg->use_delay);
447
448 /* We only want 1 person clearing the congestion count for this blkg. */
449 if (old && atomic_try_cmpxchg(v: &blkg->use_delay, old: &old, new: 0))
450 atomic_dec(v: &blkg->blkcg->css.cgroup->congestion_count);
451}
452
453/**
454 * blk_cgroup_mergeable - Determine whether to allow or disallow merges
455 * @rq: request to merge into
456 * @bio: bio to merge
457 *
458 * @bio and @rq should belong to the same cgroup and their issue_as_root should
459 * match. The latter is necessary as we don't want to throttle e.g. a metadata
460 * update because it happens to be next to a regular IO.
461 */
462static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio)
463{
464 return rq->bio->bi_blkg == bio->bi_blkg &&
465 bio_issue_as_root_blkg(bio: rq->bio) == bio_issue_as_root_blkg(bio);
466}
467
468void blk_cgroup_bio_start(struct bio *bio);
469void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
470#else /* CONFIG_BLK_CGROUP */
471
472struct blkg_policy_data {
473};
474
475struct blkcg_policy_data {
476};
477
478struct blkcg_policy {
479};
480
481struct blkcg {
482};
483
484static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
485static inline int blkcg_init_disk(struct gendisk *disk) { return 0; }
486static inline void blkcg_exit_disk(struct gendisk *disk) { }
487static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
488static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
489static inline int blkcg_activate_policy(struct gendisk *disk,
490 const struct blkcg_policy *pol) { return 0; }
491static inline void blkcg_deactivate_policy(struct gendisk *disk,
492 const struct blkcg_policy *pol) { }
493
494static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
495 struct blkcg_policy *pol) { return NULL; }
496static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
497static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
498static inline void blkg_get(struct blkcg_gq *blkg) { }
499static inline void blkg_put(struct blkcg_gq *blkg) { }
500static inline void blkcg_bio_issue_init(struct bio *bio) { }
501static inline void blk_cgroup_bio_start(struct bio *bio) { }
502static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) { return true; }
503
504#define blk_queue_for_each_rl(rl, q) \
505 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
506
507#endif /* CONFIG_BLK_CGROUP */
508
509#endif /* _BLK_CGROUP_PRIVATE_H */
510

source code of linux/block/blk-cgroup.h