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 #include "blk.h"
23
24 struct blkcg_gq;
25 struct 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
33 enum blkg_iostat_type {
34 BLKG_IOSTAT_READ,
35 BLKG_IOSTAT_WRITE,
36 BLKG_IOSTAT_DISCARD,
37
38 BLKG_IOSTAT_NR,
39 };
40
41 struct blkg_iostat {
42 u64 bytes[BLKG_IOSTAT_NR];
43 u64 ios[BLKG_IOSTAT_NR];
44 };
45
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;
53 };
54
55 /* association between a blk cgroup and a request queue */
56 struct 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
94 struct 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
122 static 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 */
138 struct 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
145 /*
146 * Policies that need to keep per-blkcg data which is independent from any
147 * request_queue associated to it should implement cpd_alloc/free_fn()
148 * methods. A policy can allocate private data area by allocating larger
149 * data structure which embeds blkcg_policy_data at the beginning.
150 * cpd_init() is invoked to let each policy handle per-blkcg data.
151 */
152 struct blkcg_policy_data {
153 /* the blkcg and policy id this per-policy data belongs to */
154 struct blkcg *blkcg;
155 int plid;
156 };
157
158 typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
159 typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
160 typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
161 typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
162 typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(struct gendisk *disk,
163 struct blkcg *blkcg, gfp_t gfp);
164 typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
165 typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
166 typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
167 typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
168 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
169 typedef void (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd,
170 struct seq_file *s);
171
172 struct blkcg_policy {
173 int plid;
174 /* cgroup files for the policy */
175 struct cftype *dfl_cftypes;
176 struct cftype *legacy_cftypes;
177
178 /* operations */
179 blkcg_pol_alloc_cpd_fn *cpd_alloc_fn;
180 blkcg_pol_free_cpd_fn *cpd_free_fn;
181
182 blkcg_pol_alloc_pd_fn *pd_alloc_fn;
183 blkcg_pol_init_pd_fn *pd_init_fn;
184 blkcg_pol_online_pd_fn *pd_online_fn;
185 blkcg_pol_offline_pd_fn *pd_offline_fn;
186 blkcg_pol_free_pd_fn *pd_free_fn;
187 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
188 blkcg_pol_stat_pd_fn *pd_stat_fn;
189 };
190
191 extern struct blkcg blkcg_root;
192 extern bool blkcg_debug_stats;
193
194 void blkg_init_queue(struct request_queue *q);
195 int blkcg_init_disk(struct gendisk *disk);
196 void blkcg_exit_disk(struct gendisk *disk);
197
198 /* Blkio controller policy registration */
199 int blkcg_policy_register(struct blkcg_policy *pol);
200 void blkcg_policy_unregister(struct blkcg_policy *pol);
201 int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol);
202 void blkcg_deactivate_policy(struct gendisk *disk,
203 const struct blkcg_policy *pol);
204
205 const char *blkg_dev_name(struct blkcg_gq *blkg);
206 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
207 u64 (*prfill)(struct seq_file *,
208 struct blkg_policy_data *, int),
209 const struct blkcg_policy *pol, int data,
210 bool show_total);
211 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
212
213 struct blkg_conf_ctx {
214 char *input;
215 char *body;
216 struct block_device *bdev;
217 struct blkcg_gq *blkg;
218 };
219
220 void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
221 int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx);
222 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
223 struct blkg_conf_ctx *ctx);
224 void blkg_conf_exit(struct blkg_conf_ctx *ctx);
225
226 /**
227 * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
228 * @return: true if this bio needs to be submitted with the root blkg context.
229 *
230 * In order to avoid priority inversions we sometimes need to issue a bio as if
231 * it were attached to the root blkg, and then backcharge to the actual owning
232 * blkg. The idea is we do bio_blkcg_css() to look up the actual context for
233 * the bio and attach the appropriate blkg to the bio. Then we call this helper
234 * and if it is true run with the root blkg for that queue and then do any
235 * backcharging to the originating cgroup once the io is complete.
236 */
237 static inline bool bio_issue_as_root_blkg(struct bio *bio)
238 {
239 return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
240 }
241
242 /**
243 * blkg_lookup - lookup blkg for the specified blkcg - q pair
244 * @blkcg: blkcg of interest
245 * @q: request_queue of interest
246 *
247 * Lookup blkg for the @blkcg - @q pair.
248
249 * Must be called in a RCU critical section.
250 */
251 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
252 struct request_queue *q)
253 {
254 struct blkcg_gq *blkg;
255
256 if (blkcg == &blkcg_root)
257 return q->root_blkg;
258
259 blkg = rcu_dereference_check(blkcg->blkg_hint,
260 lockdep_is_held(&q->queue_lock));
261 if (blkg && blkg->q == q)
262 return blkg;
263
264 blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
265 if (blkg && blkg->q != q)
266 blkg = NULL;
267 return blkg;
268 }
269
270 /**
271 * blkg_to_pdata - get policy private data
272 * @blkg: blkg of interest
273 * @pol: policy of interest
274 *
275 * Return pointer to private data associated with the @blkg-@pol pair.
276 */
277 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
278 struct blkcg_policy *pol)
279 {
280 return blkg ? blkg->pd[pol->plid] : NULL;
281 }
282
283 static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
284 struct blkcg_policy *pol)
285 {
286 return blkcg ? blkcg->cpd[pol->plid] : NULL;
287 }
288
289 /**
290 * pdata_to_blkg - get blkg associated with policy private data
291 * @pd: policy private data of interest
292 *
293 * @pd is policy private data. Determine the blkg it's associated with.
294 */
295 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
296 {
297 return pd ? pd->blkg : NULL;
298 }
299
300 static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
301 {
302 return cpd ? cpd->blkcg : NULL;
303 }
304
305 /**
306 * blkg_get - get a blkg reference
307 * @blkg: blkg to get
308 *
309 * The caller should be holding an existing reference.
310 */
311 static inline void blkg_get(struct blkcg_gq *blkg)
312 {
313 percpu_ref_get(&blkg->refcnt);
314 }
315
316 /**
317 * blkg_tryget - try and get a blkg reference
318 * @blkg: blkg to get
319 *
320 * This is for use when doing an RCU lookup of the blkg. We may be in the midst
321 * of freeing this blkg, so we can only use it if the refcnt is not zero.
322 */
323 static inline bool blkg_tryget(struct blkcg_gq *blkg)
324 {
325 return blkg && percpu_ref_tryget(&blkg->refcnt);
326 }
327
328 /**
329 * blkg_put - put a blkg reference
330 * @blkg: blkg to put
331 */
332 static inline void blkg_put(struct blkcg_gq *blkg)
333 {
334 percpu_ref_put(&blkg->refcnt);
335 }
336
337 /**
338 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
339 * @d_blkg: loop cursor pointing to the current descendant
340 * @pos_css: used for iteration
341 * @p_blkg: target blkg to walk descendants of
342 *
343 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
344 * read locked. If called under either blkcg or queue lock, the iteration
345 * is guaranteed to include all and only online blkgs. The caller may
346 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
347 * @p_blkg is included in the iteration and the first node to be visited.
348 */
349 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
350 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
351 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
352 (p_blkg)->q)))
353
354 /**
355 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
356 * @d_blkg: loop cursor pointing to the current descendant
357 * @pos_css: used for iteration
358 * @p_blkg: target blkg to walk descendants of
359 *
360 * Similar to blkg_for_each_descendant_pre() but performs post-order
361 * traversal instead. Synchronization rules are the same. @p_blkg is
362 * included in the iteration and the last node to be visited.
363 */
364 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
365 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
366 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
367 (p_blkg)->q)))
368
369 static inline void blkcg_bio_issue_init(struct bio *bio)
370 {
371 bio_issue_init(&bio->bi_issue, bio_sectors(bio));
372 }
373
374 static inline void blkcg_use_delay(struct blkcg_gq *blkg)
375 {
376 if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
377 return;
378 if (atomic_add_return(1, &blkg->use_delay) == 1)
379 atomic_inc(&blkg->blkcg->congestion_count);
380 }
381
382 static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
383 {
384 int old = atomic_read(&blkg->use_delay);
385
386 if (WARN_ON_ONCE(old < 0))
387 return 0;
388 if (old == 0)
389 return 0;
390
391 /*
392 * We do this song and dance because we can race with somebody else
393 * adding or removing delay. If we just did an atomic_dec we'd end up
394 * negative and we'd already be in trouble. We need to subtract 1 and
395 * then check to see if we were the last delay so we can drop the
396 * congestion count on the cgroup.
397 */
398 while (old && !atomic_try_cmpxchg(&blkg->use_delay, &old, old - 1))
399 ;
400
401 if (old == 0)
402 return 0;
403 if (old == 1)
404 atomic_dec(&blkg->blkcg->congestion_count);
405 return 1;
406 }
407
408 /**
409 * blkcg_set_delay - Enable allocator delay mechanism with the specified delay amount
410 * @blkg: target blkg
411 * @delay: delay duration in nsecs
412 *
413 * When enabled with this function, the delay is not decayed and must be
414 * explicitly cleared with blkcg_clear_delay(). Must not be mixed with
415 * blkcg_[un]use_delay() and blkcg_add_delay() usages.
416 */
417 static inline void blkcg_set_delay(struct blkcg_gq *blkg, u64 delay)
418 {
419 int old = atomic_read(&blkg->use_delay);
420
421 /* We only want 1 person setting the congestion count for this blkg. */
422 if (!old && atomic_try_cmpxchg(&blkg->use_delay, &old, -1))
423 atomic_inc(&blkg->blkcg->congestion_count);
424
425 atomic64_set(&blkg->delay_nsec, delay);
426 }
427
428 /**
429 * blkcg_clear_delay - Disable allocator delay mechanism
430 * @blkg: target blkg
431 *
432 * Disable use_delay mechanism. See blkcg_set_delay().
433 */
434 static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
435 {
436 int old = atomic_read(&blkg->use_delay);
437
438 /* We only want 1 person clearing the congestion count for this blkg. */
439 if (old && atomic_try_cmpxchg(&blkg->use_delay, &old, 0))
440 atomic_dec(&blkg->blkcg->congestion_count);
441 }
442
443 /**
444 * blk_cgroup_mergeable - Determine whether to allow or disallow merges
445 * @rq: request to merge into
446 * @bio: bio to merge
447 *
448 * @bio and @rq should belong to the same cgroup and their issue_as_root should
449 * match. The latter is necessary as we don't want to throttle e.g. a metadata
450 * update because it happens to be next to a regular IO.
451 */
452 static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio)
453 {
454 return rq->bio->bi_blkg == bio->bi_blkg &&
455 bio_issue_as_root_blkg(rq->bio) == bio_issue_as_root_blkg(bio);
456 }
457
458 void blk_cgroup_bio_start(struct bio *bio);
459 void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
460 #else /* CONFIG_BLK_CGROUP */
461
462 struct blkg_policy_data {
463 };
464
465 struct blkcg_policy_data {
466 };
467
468 struct blkcg_policy {
469 };
470
471 struct blkcg {
472 };
473
474 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
475 static inline void blkg_init_queue(struct request_queue *q) { }
476 static inline int blkcg_init_disk(struct gendisk *disk) { return 0; }
477 static inline void blkcg_exit_disk(struct gendisk *disk) { }
478 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
479 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
480 static inline int blkcg_activate_policy(struct gendisk *disk,
481 const struct blkcg_policy *pol) { return 0; }
482 static inline void blkcg_deactivate_policy(struct gendisk *disk,
483 const struct blkcg_policy *pol) { }
484
485 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
486 struct blkcg_policy *pol) { return NULL; }
487 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
488 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
489 static inline void blkg_get(struct blkcg_gq *blkg) { }
490 static inline void blkg_put(struct blkcg_gq *blkg) { }
491 static inline void blkcg_bio_issue_init(struct bio *bio) { }
492 static inline void blk_cgroup_bio_start(struct bio *bio) { }
493 static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) { return true; }
494
495 #define blk_queue_for_each_rl(rl, q) \
496 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
497
498 #endif /* CONFIG_BLK_CGROUP */
499
500 #endif /* _BLK_CGROUP_PRIVATE_H */
501
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