xref: /openbmc/linux/block/bfq-cgroup.c (revision faffaab2)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * cgroups support for the BFQ I/O scheduler.
4  */
5 #include <linux/module.h>
6 #include <linux/slab.h>
7 #include <linux/blkdev.h>
8 #include <linux/cgroup.h>
9 #include <linux/ktime.h>
10 #include <linux/rbtree.h>
11 #include <linux/ioprio.h>
12 #include <linux/sbitmap.h>
13 #include <linux/delay.h>
14 
15 #include "elevator.h"
16 #include "bfq-iosched.h"
17 
18 #ifdef CONFIG_BFQ_CGROUP_DEBUG
bfq_stat_init(struct bfq_stat * stat,gfp_t gfp)19 static int bfq_stat_init(struct bfq_stat *stat, gfp_t gfp)
20 {
21 	int ret;
22 
23 	ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
24 	if (ret)
25 		return ret;
26 
27 	atomic64_set(&stat->aux_cnt, 0);
28 	return 0;
29 }
30 
bfq_stat_exit(struct bfq_stat * stat)31 static void bfq_stat_exit(struct bfq_stat *stat)
32 {
33 	percpu_counter_destroy(&stat->cpu_cnt);
34 }
35 
36 /**
37  * bfq_stat_add - add a value to a bfq_stat
38  * @stat: target bfq_stat
39  * @val: value to add
40  *
41  * Add @val to @stat.  The caller must ensure that IRQ on the same CPU
42  * don't re-enter this function for the same counter.
43  */
bfq_stat_add(struct bfq_stat * stat,uint64_t val)44 static inline void bfq_stat_add(struct bfq_stat *stat, uint64_t val)
45 {
46 	percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
47 }
48 
49 /**
50  * bfq_stat_read - read the current value of a bfq_stat
51  * @stat: bfq_stat to read
52  */
bfq_stat_read(struct bfq_stat * stat)53 static inline uint64_t bfq_stat_read(struct bfq_stat *stat)
54 {
55 	return percpu_counter_sum_positive(&stat->cpu_cnt);
56 }
57 
58 /**
59  * bfq_stat_reset - reset a bfq_stat
60  * @stat: bfq_stat to reset
61  */
bfq_stat_reset(struct bfq_stat * stat)62 static inline void bfq_stat_reset(struct bfq_stat *stat)
63 {
64 	percpu_counter_set(&stat->cpu_cnt, 0);
65 	atomic64_set(&stat->aux_cnt, 0);
66 }
67 
68 /**
69  * bfq_stat_add_aux - add a bfq_stat into another's aux count
70  * @to: the destination bfq_stat
71  * @from: the source
72  *
73  * Add @from's count including the aux one to @to's aux count.
74  */
bfq_stat_add_aux(struct bfq_stat * to,struct bfq_stat * from)75 static inline void bfq_stat_add_aux(struct bfq_stat *to,
76 				     struct bfq_stat *from)
77 {
78 	atomic64_add(bfq_stat_read(from) + atomic64_read(&from->aux_cnt),
79 		     &to->aux_cnt);
80 }
81 
82 /**
83  * blkg_prfill_stat - prfill callback for bfq_stat
84  * @sf: seq_file to print to
85  * @pd: policy private data of interest
86  * @off: offset to the bfq_stat in @pd
87  *
88  * prfill callback for printing a bfq_stat.
89  */
blkg_prfill_stat(struct seq_file * sf,struct blkg_policy_data * pd,int off)90 static u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd,
91 		int off)
92 {
93 	return __blkg_prfill_u64(sf, pd, bfq_stat_read((void *)pd + off));
94 }
95 
96 /* bfqg stats flags */
97 enum bfqg_stats_flags {
98 	BFQG_stats_waiting = 0,
99 	BFQG_stats_idling,
100 	BFQG_stats_empty,
101 };
102 
103 #define BFQG_FLAG_FNS(name)						\
104 static void bfqg_stats_mark_##name(struct bfqg_stats *stats)	\
105 {									\
106 	stats->flags |= (1 << BFQG_stats_##name);			\
107 }									\
108 static void bfqg_stats_clear_##name(struct bfqg_stats *stats)	\
109 {									\
110 	stats->flags &= ~(1 << BFQG_stats_##name);			\
111 }									\
112 static int bfqg_stats_##name(struct bfqg_stats *stats)		\
113 {									\
114 	return (stats->flags & (1 << BFQG_stats_##name)) != 0;		\
115 }									\
116 
117 BFQG_FLAG_FNS(waiting)
BFQG_FLAG_FNS(idling)118 BFQG_FLAG_FNS(idling)
119 BFQG_FLAG_FNS(empty)
120 #undef BFQG_FLAG_FNS
121 
122 /* This should be called with the scheduler lock held. */
123 static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
124 {
125 	u64 now;
126 
127 	if (!bfqg_stats_waiting(stats))
128 		return;
129 
130 	now = ktime_get_ns();
131 	if (now > stats->start_group_wait_time)
132 		bfq_stat_add(&stats->group_wait_time,
133 			      now - stats->start_group_wait_time);
134 	bfqg_stats_clear_waiting(stats);
135 }
136 
137 /* This should be called with the scheduler lock held. */
bfqg_stats_set_start_group_wait_time(struct bfq_group * bfqg,struct bfq_group * curr_bfqg)138 static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
139 						 struct bfq_group *curr_bfqg)
140 {
141 	struct bfqg_stats *stats = &bfqg->stats;
142 
143 	if (bfqg_stats_waiting(stats))
144 		return;
145 	if (bfqg == curr_bfqg)
146 		return;
147 	stats->start_group_wait_time = ktime_get_ns();
148 	bfqg_stats_mark_waiting(stats);
149 }
150 
151 /* This should be called with the scheduler lock held. */
bfqg_stats_end_empty_time(struct bfqg_stats * stats)152 static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
153 {
154 	u64 now;
155 
156 	if (!bfqg_stats_empty(stats))
157 		return;
158 
159 	now = ktime_get_ns();
160 	if (now > stats->start_empty_time)
161 		bfq_stat_add(&stats->empty_time,
162 			      now - stats->start_empty_time);
163 	bfqg_stats_clear_empty(stats);
164 }
165 
bfqg_stats_update_dequeue(struct bfq_group * bfqg)166 void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
167 {
168 	bfq_stat_add(&bfqg->stats.dequeue, 1);
169 }
170 
bfqg_stats_set_start_empty_time(struct bfq_group * bfqg)171 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
172 {
173 	struct bfqg_stats *stats = &bfqg->stats;
174 
175 	if (blkg_rwstat_total(&stats->queued))
176 		return;
177 
178 	/*
179 	 * group is already marked empty. This can happen if bfqq got new
180 	 * request in parent group and moved to this group while being added
181 	 * to service tree. Just ignore the event and move on.
182 	 */
183 	if (bfqg_stats_empty(stats))
184 		return;
185 
186 	stats->start_empty_time = ktime_get_ns();
187 	bfqg_stats_mark_empty(stats);
188 }
189 
bfqg_stats_update_idle_time(struct bfq_group * bfqg)190 void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
191 {
192 	struct bfqg_stats *stats = &bfqg->stats;
193 
194 	if (bfqg_stats_idling(stats)) {
195 		u64 now = ktime_get_ns();
196 
197 		if (now > stats->start_idle_time)
198 			bfq_stat_add(&stats->idle_time,
199 				      now - stats->start_idle_time);
200 		bfqg_stats_clear_idling(stats);
201 	}
202 }
203 
bfqg_stats_set_start_idle_time(struct bfq_group * bfqg)204 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
205 {
206 	struct bfqg_stats *stats = &bfqg->stats;
207 
208 	stats->start_idle_time = ktime_get_ns();
209 	bfqg_stats_mark_idling(stats);
210 }
211 
bfqg_stats_update_avg_queue_size(struct bfq_group * bfqg)212 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
213 {
214 	struct bfqg_stats *stats = &bfqg->stats;
215 
216 	bfq_stat_add(&stats->avg_queue_size_sum,
217 		      blkg_rwstat_total(&stats->queued));
218 	bfq_stat_add(&stats->avg_queue_size_samples, 1);
219 	bfqg_stats_update_group_wait_time(stats);
220 }
221 
bfqg_stats_update_io_add(struct bfq_group * bfqg,struct bfq_queue * bfqq,blk_opf_t opf)222 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
223 			      blk_opf_t opf)
224 {
225 	blkg_rwstat_add(&bfqg->stats.queued, opf, 1);
226 	bfqg_stats_end_empty_time(&bfqg->stats);
227 	if (!(bfqq == bfqg->bfqd->in_service_queue))
228 		bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
229 }
230 
bfqg_stats_update_io_remove(struct bfq_group * bfqg,blk_opf_t opf)231 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, blk_opf_t opf)
232 {
233 	blkg_rwstat_add(&bfqg->stats.queued, opf, -1);
234 }
235 
bfqg_stats_update_io_merged(struct bfq_group * bfqg,blk_opf_t opf)236 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf)
237 {
238 	blkg_rwstat_add(&bfqg->stats.merged, opf, 1);
239 }
240 
bfqg_stats_update_completion(struct bfq_group * bfqg,u64 start_time_ns,u64 io_start_time_ns,blk_opf_t opf)241 void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
242 				  u64 io_start_time_ns, blk_opf_t opf)
243 {
244 	struct bfqg_stats *stats = &bfqg->stats;
245 	u64 now = ktime_get_ns();
246 
247 	if (now > io_start_time_ns)
248 		blkg_rwstat_add(&stats->service_time, opf,
249 				now - io_start_time_ns);
250 	if (io_start_time_ns > start_time_ns)
251 		blkg_rwstat_add(&stats->wait_time, opf,
252 				io_start_time_ns - start_time_ns);
253 }
254 
255 #else /* CONFIG_BFQ_CGROUP_DEBUG */
256 
bfqg_stats_update_io_remove(struct bfq_group * bfqg,blk_opf_t opf)257 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, blk_opf_t opf) { }
bfqg_stats_update_io_merged(struct bfq_group * bfqg,blk_opf_t opf)258 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf) { }
bfqg_stats_update_completion(struct bfq_group * bfqg,u64 start_time_ns,u64 io_start_time_ns,blk_opf_t opf)259 void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
260 				  u64 io_start_time_ns, blk_opf_t opf) { }
bfqg_stats_update_dequeue(struct bfq_group * bfqg)261 void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
bfqg_stats_set_start_idle_time(struct bfq_group * bfqg)262 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
263 
264 #endif /* CONFIG_BFQ_CGROUP_DEBUG */
265 
266 #ifdef CONFIG_BFQ_GROUP_IOSCHED
267 
268 /*
269  * blk-cgroup policy-related handlers
270  * The following functions help in converting between blk-cgroup
271  * internal structures and BFQ-specific structures.
272  */
273 
pd_to_bfqg(struct blkg_policy_data * pd)274 static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
275 {
276 	return pd ? container_of(pd, struct bfq_group, pd) : NULL;
277 }
278 
bfqg_to_blkg(struct bfq_group * bfqg)279 struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
280 {
281 	return pd_to_blkg(&bfqg->pd);
282 }
283 
blkg_to_bfqg(struct blkcg_gq * blkg)284 static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
285 {
286 	return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq));
287 }
288 
289 /*
290  * bfq_group handlers
291  * The following functions help in navigating the bfq_group hierarchy
292  * by allowing to find the parent of a bfq_group or the bfq_group
293  * associated to a bfq_queue.
294  */
295 
bfqg_parent(struct bfq_group * bfqg)296 static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
297 {
298 	struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
299 
300 	return pblkg ? blkg_to_bfqg(pblkg) : NULL;
301 }
302 
bfqq_group(struct bfq_queue * bfqq)303 struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
304 {
305 	struct bfq_entity *group_entity = bfqq->entity.parent;
306 
307 	return group_entity ? container_of(group_entity, struct bfq_group,
308 					   entity) :
309 			      bfqq->bfqd->root_group;
310 }
311 
312 /*
313  * The following two functions handle get and put of a bfq_group by
314  * wrapping the related blk-cgroup hooks.
315  */
316 
bfqg_get(struct bfq_group * bfqg)317 static void bfqg_get(struct bfq_group *bfqg)
318 {
319 	refcount_inc(&bfqg->ref);
320 }
321 
bfqg_put(struct bfq_group * bfqg)322 static void bfqg_put(struct bfq_group *bfqg)
323 {
324 	if (refcount_dec_and_test(&bfqg->ref))
325 		kfree(bfqg);
326 }
327 
bfqg_and_blkg_get(struct bfq_group * bfqg)328 static void bfqg_and_blkg_get(struct bfq_group *bfqg)
329 {
330 	/* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
331 	bfqg_get(bfqg);
332 
333 	blkg_get(bfqg_to_blkg(bfqg));
334 }
335 
bfqg_and_blkg_put(struct bfq_group * bfqg)336 void bfqg_and_blkg_put(struct bfq_group *bfqg)
337 {
338 	blkg_put(bfqg_to_blkg(bfqg));
339 
340 	bfqg_put(bfqg);
341 }
342 
bfqg_stats_update_legacy_io(struct request_queue * q,struct request * rq)343 void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq)
344 {
345 	struct bfq_group *bfqg = blkg_to_bfqg(rq->bio->bi_blkg);
346 
347 	if (!bfqg)
348 		return;
349 
350 	blkg_rwstat_add(&bfqg->stats.bytes, rq->cmd_flags, blk_rq_bytes(rq));
351 	blkg_rwstat_add(&bfqg->stats.ios, rq->cmd_flags, 1);
352 }
353 
354 /* @stats = 0 */
bfqg_stats_reset(struct bfqg_stats * stats)355 static void bfqg_stats_reset(struct bfqg_stats *stats)
356 {
357 #ifdef CONFIG_BFQ_CGROUP_DEBUG
358 	/* queued stats shouldn't be cleared */
359 	blkg_rwstat_reset(&stats->merged);
360 	blkg_rwstat_reset(&stats->service_time);
361 	blkg_rwstat_reset(&stats->wait_time);
362 	bfq_stat_reset(&stats->time);
363 	bfq_stat_reset(&stats->avg_queue_size_sum);
364 	bfq_stat_reset(&stats->avg_queue_size_samples);
365 	bfq_stat_reset(&stats->dequeue);
366 	bfq_stat_reset(&stats->group_wait_time);
367 	bfq_stat_reset(&stats->idle_time);
368 	bfq_stat_reset(&stats->empty_time);
369 #endif
370 }
371 
372 /* @to += @from */
bfqg_stats_add_aux(struct bfqg_stats * to,struct bfqg_stats * from)373 static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
374 {
375 	if (!to || !from)
376 		return;
377 
378 #ifdef CONFIG_BFQ_CGROUP_DEBUG
379 	/* queued stats shouldn't be cleared */
380 	blkg_rwstat_add_aux(&to->merged, &from->merged);
381 	blkg_rwstat_add_aux(&to->service_time, &from->service_time);
382 	blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
383 	bfq_stat_add_aux(&from->time, &from->time);
384 	bfq_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
385 	bfq_stat_add_aux(&to->avg_queue_size_samples,
386 			  &from->avg_queue_size_samples);
387 	bfq_stat_add_aux(&to->dequeue, &from->dequeue);
388 	bfq_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
389 	bfq_stat_add_aux(&to->idle_time, &from->idle_time);
390 	bfq_stat_add_aux(&to->empty_time, &from->empty_time);
391 #endif
392 }
393 
394 /*
395  * Transfer @bfqg's stats to its parent's aux counts so that the ancestors'
396  * recursive stats can still account for the amount used by this bfqg after
397  * it's gone.
398  */
bfqg_stats_xfer_dead(struct bfq_group * bfqg)399 static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
400 {
401 	struct bfq_group *parent;
402 
403 	if (!bfqg) /* root_group */
404 		return;
405 
406 	parent = bfqg_parent(bfqg);
407 
408 	lockdep_assert_held(&bfqg_to_blkg(bfqg)->q->queue_lock);
409 
410 	if (unlikely(!parent))
411 		return;
412 
413 	bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
414 	bfqg_stats_reset(&bfqg->stats);
415 }
416 
bfq_init_entity(struct bfq_entity * entity,struct bfq_group * bfqg)417 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
418 {
419 	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
420 
421 	entity->weight = entity->new_weight;
422 	entity->orig_weight = entity->new_weight;
423 	if (bfqq) {
424 		bfqq->ioprio = bfqq->new_ioprio;
425 		bfqq->ioprio_class = bfqq->new_ioprio_class;
426 		/*
427 		 * Make sure that bfqg and its associated blkg do not
428 		 * disappear before entity.
429 		 */
430 		bfqg_and_blkg_get(bfqg);
431 	}
432 	entity->parent = bfqg->my_entity; /* NULL for root group */
433 	entity->sched_data = &bfqg->sched_data;
434 }
435 
bfqg_stats_exit(struct bfqg_stats * stats)436 static void bfqg_stats_exit(struct bfqg_stats *stats)
437 {
438 	blkg_rwstat_exit(&stats->bytes);
439 	blkg_rwstat_exit(&stats->ios);
440 #ifdef CONFIG_BFQ_CGROUP_DEBUG
441 	blkg_rwstat_exit(&stats->merged);
442 	blkg_rwstat_exit(&stats->service_time);
443 	blkg_rwstat_exit(&stats->wait_time);
444 	blkg_rwstat_exit(&stats->queued);
445 	bfq_stat_exit(&stats->time);
446 	bfq_stat_exit(&stats->avg_queue_size_sum);
447 	bfq_stat_exit(&stats->avg_queue_size_samples);
448 	bfq_stat_exit(&stats->dequeue);
449 	bfq_stat_exit(&stats->group_wait_time);
450 	bfq_stat_exit(&stats->idle_time);
451 	bfq_stat_exit(&stats->empty_time);
452 #endif
453 }
454 
bfqg_stats_init(struct bfqg_stats * stats,gfp_t gfp)455 static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
456 {
457 	if (blkg_rwstat_init(&stats->bytes, gfp) ||
458 	    blkg_rwstat_init(&stats->ios, gfp))
459 		goto error;
460 
461 #ifdef CONFIG_BFQ_CGROUP_DEBUG
462 	if (blkg_rwstat_init(&stats->merged, gfp) ||
463 	    blkg_rwstat_init(&stats->service_time, gfp) ||
464 	    blkg_rwstat_init(&stats->wait_time, gfp) ||
465 	    blkg_rwstat_init(&stats->queued, gfp) ||
466 	    bfq_stat_init(&stats->time, gfp) ||
467 	    bfq_stat_init(&stats->avg_queue_size_sum, gfp) ||
468 	    bfq_stat_init(&stats->avg_queue_size_samples, gfp) ||
469 	    bfq_stat_init(&stats->dequeue, gfp) ||
470 	    bfq_stat_init(&stats->group_wait_time, gfp) ||
471 	    bfq_stat_init(&stats->idle_time, gfp) ||
472 	    bfq_stat_init(&stats->empty_time, gfp))
473 		goto error;
474 #endif
475 
476 	return 0;
477 
478 error:
479 	bfqg_stats_exit(stats);
480 	return -ENOMEM;
481 }
482 
cpd_to_bfqgd(struct blkcg_policy_data * cpd)483 static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
484 {
485 	return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
486 }
487 
blkcg_to_bfqgd(struct blkcg * blkcg)488 static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
489 {
490 	return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
491 }
492 
bfq_cpd_alloc(gfp_t gfp)493 static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
494 {
495 	struct bfq_group_data *bgd;
496 
497 	bgd = kzalloc(sizeof(*bgd), gfp);
498 	if (!bgd)
499 		return NULL;
500 
501 	bgd->weight = CGROUP_WEIGHT_DFL;
502 	return &bgd->pd;
503 }
504 
bfq_cpd_free(struct blkcg_policy_data * cpd)505 static void bfq_cpd_free(struct blkcg_policy_data *cpd)
506 {
507 	kfree(cpd_to_bfqgd(cpd));
508 }
509 
bfq_pd_alloc(struct gendisk * disk,struct blkcg * blkcg,gfp_t gfp)510 static struct blkg_policy_data *bfq_pd_alloc(struct gendisk *disk,
511 		struct blkcg *blkcg, gfp_t gfp)
512 {
513 	struct bfq_group *bfqg;
514 
515 	bfqg = kzalloc_node(sizeof(*bfqg), gfp, disk->node_id);
516 	if (!bfqg)
517 		return NULL;
518 
519 	if (bfqg_stats_init(&bfqg->stats, gfp)) {
520 		kfree(bfqg);
521 		return NULL;
522 	}
523 
524 	/* see comments in bfq_bic_update_cgroup for why refcounting */
525 	refcount_set(&bfqg->ref, 1);
526 	return &bfqg->pd;
527 }
528 
bfq_pd_init(struct blkg_policy_data * pd)529 static void bfq_pd_init(struct blkg_policy_data *pd)
530 {
531 	struct blkcg_gq *blkg = pd_to_blkg(pd);
532 	struct bfq_group *bfqg = blkg_to_bfqg(blkg);
533 	struct bfq_data *bfqd = blkg->q->elevator->elevator_data;
534 	struct bfq_entity *entity = &bfqg->entity;
535 	struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg);
536 
537 	entity->orig_weight = entity->weight = entity->new_weight = d->weight;
538 	entity->my_sched_data = &bfqg->sched_data;
539 	entity->last_bfqq_created = NULL;
540 
541 	bfqg->my_entity = entity; /*
542 				   * the root_group's will be set to NULL
543 				   * in bfq_init_queue()
544 				   */
545 	bfqg->bfqd = bfqd;
546 	bfqg->active_entities = 0;
547 	bfqg->num_queues_with_pending_reqs = 0;
548 	bfqg->rq_pos_tree = RB_ROOT;
549 }
550 
bfq_pd_free(struct blkg_policy_data * pd)551 static void bfq_pd_free(struct blkg_policy_data *pd)
552 {
553 	struct bfq_group *bfqg = pd_to_bfqg(pd);
554 
555 	bfqg_stats_exit(&bfqg->stats);
556 	bfqg_put(bfqg);
557 }
558 
bfq_pd_reset_stats(struct blkg_policy_data * pd)559 static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
560 {
561 	struct bfq_group *bfqg = pd_to_bfqg(pd);
562 
563 	bfqg_stats_reset(&bfqg->stats);
564 }
565 
bfq_group_set_parent(struct bfq_group * bfqg,struct bfq_group * parent)566 static void bfq_group_set_parent(struct bfq_group *bfqg,
567 					struct bfq_group *parent)
568 {
569 	struct bfq_entity *entity;
570 
571 	entity = &bfqg->entity;
572 	entity->parent = parent->my_entity;
573 	entity->sched_data = &parent->sched_data;
574 }
575 
bfq_link_bfqg(struct bfq_data * bfqd,struct bfq_group * bfqg)576 static void bfq_link_bfqg(struct bfq_data *bfqd, struct bfq_group *bfqg)
577 {
578 	struct bfq_group *parent;
579 	struct bfq_entity *entity;
580 
581 	/*
582 	 * Update chain of bfq_groups as we might be handling a leaf group
583 	 * which, along with some of its relatives, has not been hooked yet
584 	 * to the private hierarchy of BFQ.
585 	 */
586 	entity = &bfqg->entity;
587 	for_each_entity(entity) {
588 		struct bfq_group *curr_bfqg = container_of(entity,
589 						struct bfq_group, entity);
590 		if (curr_bfqg != bfqd->root_group) {
591 			parent = bfqg_parent(curr_bfqg);
592 			if (!parent)
593 				parent = bfqd->root_group;
594 			bfq_group_set_parent(curr_bfqg, parent);
595 		}
596 	}
597 }
598 
bfq_bio_bfqg(struct bfq_data * bfqd,struct bio * bio)599 struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio)
600 {
601 	struct blkcg_gq *blkg = bio->bi_blkg;
602 	struct bfq_group *bfqg;
603 
604 	while (blkg) {
605 		if (!blkg->online) {
606 			blkg = blkg->parent;
607 			continue;
608 		}
609 		bfqg = blkg_to_bfqg(blkg);
610 		if (bfqg->pd.online) {
611 			bio_associate_blkg_from_css(bio, &blkg->blkcg->css);
612 			return bfqg;
613 		}
614 		blkg = blkg->parent;
615 	}
616 	bio_associate_blkg_from_css(bio,
617 				&bfqg_to_blkg(bfqd->root_group)->blkcg->css);
618 	return bfqd->root_group;
619 }
620 
621 /**
622  * bfq_bfqq_move - migrate @bfqq to @bfqg.
623  * @bfqd: queue descriptor.
624  * @bfqq: the queue to move.
625  * @bfqg: the group to move to.
626  *
627  * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
628  * it on the new one.  Avoid putting the entity on the old group idle tree.
629  *
630  * Must be called under the scheduler lock, to make sure that the blkg
631  * owning @bfqg does not disappear (see comments in
632  * bfq_bic_update_cgroup on guaranteeing the consistency of blkg
633  * objects).
634  */
bfq_bfqq_move(struct bfq_data * bfqd,struct bfq_queue * bfqq,struct bfq_group * bfqg)635 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
636 		   struct bfq_group *bfqg)
637 {
638 	struct bfq_entity *entity = &bfqq->entity;
639 	struct bfq_group *old_parent = bfqq_group(bfqq);
640 	bool has_pending_reqs = false;
641 
642 	/*
643 	 * No point to move bfqq to the same group, which can happen when
644 	 * root group is offlined
645 	 */
646 	if (old_parent == bfqg)
647 		return;
648 
649 	/*
650 	 * oom_bfqq is not allowed to move, oom_bfqq will hold ref to root_group
651 	 * until elevator exit.
652 	 */
653 	if (bfqq == &bfqd->oom_bfqq)
654 		return;
655 	/*
656 	 * Get extra reference to prevent bfqq from being freed in
657 	 * next possible expire or deactivate.
658 	 */
659 	bfqq->ref++;
660 
661 	if (entity->in_groups_with_pending_reqs) {
662 		has_pending_reqs = true;
663 		bfq_del_bfqq_in_groups_with_pending_reqs(bfqq);
664 	}
665 
666 	/* If bfqq is empty, then bfq_bfqq_expire also invokes
667 	 * bfq_del_bfqq_busy, thereby removing bfqq and its entity
668 	 * from data structures related to current group. Otherwise we
669 	 * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
670 	 * we do below.
671 	 */
672 	if (bfqq == bfqd->in_service_queue)
673 		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
674 				false, BFQQE_PREEMPTED);
675 
676 	if (bfq_bfqq_busy(bfqq))
677 		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
678 	else if (entity->on_st_or_in_serv)
679 		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
680 	bfqg_and_blkg_put(old_parent);
681 
682 	if (entity->parent &&
683 	    entity->parent->last_bfqq_created == bfqq)
684 		entity->parent->last_bfqq_created = NULL;
685 	else if (bfqd->last_bfqq_created == bfqq)
686 		bfqd->last_bfqq_created = NULL;
687 
688 	entity->parent = bfqg->my_entity;
689 	entity->sched_data = &bfqg->sched_data;
690 	/* pin down bfqg and its associated blkg  */
691 	bfqg_and_blkg_get(bfqg);
692 
693 	if (has_pending_reqs)
694 		bfq_add_bfqq_in_groups_with_pending_reqs(bfqq);
695 
696 	if (bfq_bfqq_busy(bfqq)) {
697 		if (unlikely(!bfqd->nonrot_with_queueing))
698 			bfq_pos_tree_add_move(bfqd, bfqq);
699 		bfq_activate_bfqq(bfqd, bfqq);
700 	}
701 
702 	if (!bfqd->in_service_queue && !bfqd->tot_rq_in_driver)
703 		bfq_schedule_dispatch(bfqd);
704 	/* release extra ref taken above, bfqq may happen to be freed now */
705 	bfq_put_queue(bfqq);
706 }
707 
bfq_sync_bfqq_move(struct bfq_data * bfqd,struct bfq_queue * sync_bfqq,struct bfq_io_cq * bic,struct bfq_group * bfqg,unsigned int act_idx)708 static void bfq_sync_bfqq_move(struct bfq_data *bfqd,
709 			       struct bfq_queue *sync_bfqq,
710 			       struct bfq_io_cq *bic,
711 			       struct bfq_group *bfqg,
712 			       unsigned int act_idx)
713 {
714 	struct bfq_queue *bfqq;
715 
716 	if (!sync_bfqq->new_bfqq && !bfq_bfqq_coop(sync_bfqq)) {
717 		/* We are the only user of this bfqq, just move it */
718 		if (sync_bfqq->entity.sched_data != &bfqg->sched_data)
719 			bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
720 		return;
721 	}
722 
723 	/*
724 	 * The queue was merged to a different queue. Check
725 	 * that the merge chain still belongs to the same
726 	 * cgroup.
727 	 */
728 	for (bfqq = sync_bfqq; bfqq; bfqq = bfqq->new_bfqq)
729 		if (bfqq->entity.sched_data != &bfqg->sched_data)
730 			break;
731 	if (bfqq) {
732 		/*
733 		 * Some queue changed cgroup so the merge is not valid
734 		 * anymore. We cannot easily just cancel the merge (by
735 		 * clearing new_bfqq) as there may be other processes
736 		 * using this queue and holding refs to all queues
737 		 * below sync_bfqq->new_bfqq. Similarly if the merge
738 		 * already happened, we need to detach from bfqq now
739 		 * so that we cannot merge bio to a request from the
740 		 * old cgroup.
741 		 */
742 		bfq_put_cooperator(sync_bfqq);
743 		bic_set_bfqq(bic, NULL, true, act_idx);
744 		bfq_release_process_ref(bfqd, sync_bfqq);
745 	}
746 }
747 
748 /**
749  * __bfq_bic_change_cgroup - move @bic to @bfqg.
750  * @bfqd: the queue descriptor.
751  * @bic: the bic to move.
752  * @bfqg: the group to move to.
753  *
754  * Move bic to blkcg, assuming that bfqd->lock is held; which makes
755  * sure that the reference to cgroup is valid across the call (see
756  * comments in bfq_bic_update_cgroup on this issue)
757  */
__bfq_bic_change_cgroup(struct bfq_data * bfqd,struct bfq_io_cq * bic,struct bfq_group * bfqg)758 static void __bfq_bic_change_cgroup(struct bfq_data *bfqd,
759 				    struct bfq_io_cq *bic,
760 				    struct bfq_group *bfqg)
761 {
762 	unsigned int act_idx;
763 
764 	for (act_idx = 0; act_idx < bfqd->num_actuators; act_idx++) {
765 		struct bfq_queue *async_bfqq = bic_to_bfqq(bic, false, act_idx);
766 		struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, true, act_idx);
767 
768 		if (async_bfqq &&
769 		    async_bfqq->entity.sched_data != &bfqg->sched_data) {
770 			bic_set_bfqq(bic, NULL, false, act_idx);
771 			bfq_release_process_ref(bfqd, async_bfqq);
772 		}
773 
774 		if (sync_bfqq)
775 			bfq_sync_bfqq_move(bfqd, sync_bfqq, bic, bfqg, act_idx);
776 	}
777 }
778 
bfq_bic_update_cgroup(struct bfq_io_cq * bic,struct bio * bio)779 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
780 {
781 	struct bfq_data *bfqd = bic_to_bfqd(bic);
782 	struct bfq_group *bfqg = bfq_bio_bfqg(bfqd, bio);
783 	uint64_t serial_nr;
784 
785 	serial_nr = bfqg_to_blkg(bfqg)->blkcg->css.serial_nr;
786 
787 	/*
788 	 * Check whether blkcg has changed.  The condition may trigger
789 	 * spuriously on a newly created cic but there's no harm.
790 	 */
791 	if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
792 		return;
793 
794 	/*
795 	 * New cgroup for this process. Make sure it is linked to bfq internal
796 	 * cgroup hierarchy.
797 	 */
798 	bfq_link_bfqg(bfqd, bfqg);
799 	__bfq_bic_change_cgroup(bfqd, bic, bfqg);
800 	/*
801 	 * Update blkg_path for bfq_log_* functions. We cache this
802 	 * path, and update it here, for the following
803 	 * reasons. Operations on blkg objects in blk-cgroup are
804 	 * protected with the request_queue lock, and not with the
805 	 * lock that protects the instances of this scheduler
806 	 * (bfqd->lock). This exposes BFQ to the following sort of
807 	 * race.
808 	 *
809 	 * The blkg_lookup performed in bfq_get_queue, protected
810 	 * through rcu, may happen to return the address of a copy of
811 	 * the original blkg. If this is the case, then the
812 	 * bfqg_and_blkg_get performed in bfq_get_queue, to pin down
813 	 * the blkg, is useless: it does not prevent blk-cgroup code
814 	 * from destroying both the original blkg and all objects
815 	 * directly or indirectly referred by the copy of the
816 	 * blkg.
817 	 *
818 	 * On the bright side, destroy operations on a blkg invoke, as
819 	 * a first step, hooks of the scheduler associated with the
820 	 * blkg. And these hooks are executed with bfqd->lock held for
821 	 * BFQ. As a consequence, for any blkg associated with the
822 	 * request queue this instance of the scheduler is attached
823 	 * to, we are guaranteed that such a blkg is not destroyed, and
824 	 * that all the pointers it contains are consistent, while we
825 	 * are holding bfqd->lock. A blkg_lookup performed with
826 	 * bfqd->lock held then returns a fully consistent blkg, which
827 	 * remains consistent until this lock is held.
828 	 *
829 	 * Thanks to the last fact, and to the fact that: (1) bfqg has
830 	 * been obtained through a blkg_lookup in the above
831 	 * assignment, and (2) bfqd->lock is being held, here we can
832 	 * safely use the policy data for the involved blkg (i.e., the
833 	 * field bfqg->pd) to get to the blkg associated with bfqg,
834 	 * and then we can safely use any field of blkg. After we
835 	 * release bfqd->lock, even just getting blkg through this
836 	 * bfqg may cause dangling references to be traversed, as
837 	 * bfqg->pd may not exist any more.
838 	 *
839 	 * In view of the above facts, here we cache, in the bfqg, any
840 	 * blkg data we may need for this bic, and for its associated
841 	 * bfq_queue. As of now, we need to cache only the path of the
842 	 * blkg, which is used in the bfq_log_* functions.
843 	 *
844 	 * Finally, note that bfqg itself needs to be protected from
845 	 * destruction on the blkg_free of the original blkg (which
846 	 * invokes bfq_pd_free). We use an additional private
847 	 * refcounter for bfqg, to let it disappear only after no
848 	 * bfq_queue refers to it any longer.
849 	 */
850 	blkg_path(bfqg_to_blkg(bfqg), bfqg->blkg_path, sizeof(bfqg->blkg_path));
851 	bic->blkcg_serial_nr = serial_nr;
852 }
853 
854 /**
855  * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
856  * @st: the service tree being flushed.
857  */
bfq_flush_idle_tree(struct bfq_service_tree * st)858 static void bfq_flush_idle_tree(struct bfq_service_tree *st)
859 {
860 	struct bfq_entity *entity = st->first_idle;
861 
862 	for (; entity ; entity = st->first_idle)
863 		__bfq_deactivate_entity(entity, false);
864 }
865 
866 /**
867  * bfq_reparent_leaf_entity - move leaf entity to the root_group.
868  * @bfqd: the device data structure with the root group.
869  * @entity: the entity to move, if entity is a leaf; or the parent entity
870  *	    of an active leaf entity to move, if entity is not a leaf.
871  * @ioprio_class: I/O priority class to reparent.
872  */
bfq_reparent_leaf_entity(struct bfq_data * bfqd,struct bfq_entity * entity,int ioprio_class)873 static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
874 				     struct bfq_entity *entity,
875 				     int ioprio_class)
876 {
877 	struct bfq_queue *bfqq;
878 	struct bfq_entity *child_entity = entity;
879 
880 	while (child_entity->my_sched_data) { /* leaf not reached yet */
881 		struct bfq_sched_data *child_sd = child_entity->my_sched_data;
882 		struct bfq_service_tree *child_st = child_sd->service_tree +
883 			ioprio_class;
884 		struct rb_root *child_active = &child_st->active;
885 
886 		child_entity = bfq_entity_of(rb_first(child_active));
887 
888 		if (!child_entity)
889 			child_entity = child_sd->in_service_entity;
890 	}
891 
892 	bfqq = bfq_entity_to_bfqq(child_entity);
893 	bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
894 }
895 
896 /**
897  * bfq_reparent_active_queues - move to the root group all active queues.
898  * @bfqd: the device data structure with the root group.
899  * @bfqg: the group to move from.
900  * @st: the service tree to start the search from.
901  * @ioprio_class: I/O priority class to reparent.
902  */
bfq_reparent_active_queues(struct bfq_data * bfqd,struct bfq_group * bfqg,struct bfq_service_tree * st,int ioprio_class)903 static void bfq_reparent_active_queues(struct bfq_data *bfqd,
904 				       struct bfq_group *bfqg,
905 				       struct bfq_service_tree *st,
906 				       int ioprio_class)
907 {
908 	struct rb_root *active = &st->active;
909 	struct bfq_entity *entity;
910 
911 	while ((entity = bfq_entity_of(rb_first(active))))
912 		bfq_reparent_leaf_entity(bfqd, entity, ioprio_class);
913 
914 	if (bfqg->sched_data.in_service_entity)
915 		bfq_reparent_leaf_entity(bfqd,
916 					 bfqg->sched_data.in_service_entity,
917 					 ioprio_class);
918 }
919 
920 /**
921  * bfq_pd_offline - deactivate the entity associated with @pd,
922  *		    and reparent its children entities.
923  * @pd: descriptor of the policy going offline.
924  *
925  * blkio already grabs the queue_lock for us, so no need to use
926  * RCU-based magic
927  */
bfq_pd_offline(struct blkg_policy_data * pd)928 static void bfq_pd_offline(struct blkg_policy_data *pd)
929 {
930 	struct bfq_service_tree *st;
931 	struct bfq_group *bfqg = pd_to_bfqg(pd);
932 	struct bfq_data *bfqd = bfqg->bfqd;
933 	struct bfq_entity *entity = bfqg->my_entity;
934 	unsigned long flags;
935 	int i;
936 
937 	spin_lock_irqsave(&bfqd->lock, flags);
938 
939 	if (!entity) /* root group */
940 		goto put_async_queues;
941 
942 	/*
943 	 * Empty all service_trees belonging to this group before
944 	 * deactivating the group itself.
945 	 */
946 	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
947 		st = bfqg->sched_data.service_tree + i;
948 
949 		/*
950 		 * It may happen that some queues are still active
951 		 * (busy) upon group destruction (if the corresponding
952 		 * processes have been forced to terminate). We move
953 		 * all the leaf entities corresponding to these queues
954 		 * to the root_group.
955 		 * Also, it may happen that the group has an entity
956 		 * in service, which is disconnected from the active
957 		 * tree: it must be moved, too.
958 		 * There is no need to put the sync queues, as the
959 		 * scheduler has taken no reference.
960 		 */
961 		bfq_reparent_active_queues(bfqd, bfqg, st, i);
962 
963 		/*
964 		 * The idle tree may still contain bfq_queues
965 		 * belonging to exited task because they never
966 		 * migrated to a different cgroup from the one being
967 		 * destroyed now. In addition, even
968 		 * bfq_reparent_active_queues() may happen to add some
969 		 * entities to the idle tree. It happens if, in some
970 		 * of the calls to bfq_bfqq_move() performed by
971 		 * bfq_reparent_active_queues(), the queue to move is
972 		 * empty and gets expired.
973 		 */
974 		bfq_flush_idle_tree(st);
975 	}
976 
977 	__bfq_deactivate_entity(entity, false);
978 
979 put_async_queues:
980 	bfq_put_async_queues(bfqd, bfqg);
981 
982 	spin_unlock_irqrestore(&bfqd->lock, flags);
983 	/*
984 	 * @blkg is going offline and will be ignored by
985 	 * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
986 	 * that they don't get lost.  If IOs complete after this point, the
987 	 * stats for them will be lost.  Oh well...
988 	 */
989 	bfqg_stats_xfer_dead(bfqg);
990 }
991 
bfq_end_wr_async(struct bfq_data * bfqd)992 void bfq_end_wr_async(struct bfq_data *bfqd)
993 {
994 	struct blkcg_gq *blkg;
995 
996 	list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
997 		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
998 
999 		bfq_end_wr_async_queues(bfqd, bfqg);
1000 	}
1001 	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
1002 }
1003 
bfq_io_show_weight_legacy(struct seq_file * sf,void * v)1004 static int bfq_io_show_weight_legacy(struct seq_file *sf, void *v)
1005 {
1006 	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1007 	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
1008 	unsigned int val = 0;
1009 
1010 	if (bfqgd)
1011 		val = bfqgd->weight;
1012 
1013 	seq_printf(sf, "%u\n", val);
1014 
1015 	return 0;
1016 }
1017 
bfqg_prfill_weight_device(struct seq_file * sf,struct blkg_policy_data * pd,int off)1018 static u64 bfqg_prfill_weight_device(struct seq_file *sf,
1019 				     struct blkg_policy_data *pd, int off)
1020 {
1021 	struct bfq_group *bfqg = pd_to_bfqg(pd);
1022 
1023 	if (!bfqg->entity.dev_weight)
1024 		return 0;
1025 	return __blkg_prfill_u64(sf, pd, bfqg->entity.dev_weight);
1026 }
1027 
bfq_io_show_weight(struct seq_file * sf,void * v)1028 static int bfq_io_show_weight(struct seq_file *sf, void *v)
1029 {
1030 	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1031 	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
1032 
1033 	seq_printf(sf, "default %u\n", bfqgd->weight);
1034 	blkcg_print_blkgs(sf, blkcg, bfqg_prfill_weight_device,
1035 			  &blkcg_policy_bfq, 0, false);
1036 	return 0;
1037 }
1038 
bfq_group_set_weight(struct bfq_group * bfqg,u64 weight,u64 dev_weight)1039 static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight, u64 dev_weight)
1040 {
1041 	weight = dev_weight ?: weight;
1042 
1043 	bfqg->entity.dev_weight = dev_weight;
1044 	/*
1045 	 * Setting the prio_changed flag of the entity
1046 	 * to 1 with new_weight == weight would re-set
1047 	 * the value of the weight to its ioprio mapping.
1048 	 * Set the flag only if necessary.
1049 	 */
1050 	if ((unsigned short)weight != bfqg->entity.new_weight) {
1051 		bfqg->entity.new_weight = (unsigned short)weight;
1052 		/*
1053 		 * Make sure that the above new value has been
1054 		 * stored in bfqg->entity.new_weight before
1055 		 * setting the prio_changed flag. In fact,
1056 		 * this flag may be read asynchronously (in
1057 		 * critical sections protected by a different
1058 		 * lock than that held here), and finding this
1059 		 * flag set may cause the execution of the code
1060 		 * for updating parameters whose value may
1061 		 * depend also on bfqg->entity.new_weight (in
1062 		 * __bfq_entity_update_weight_prio).
1063 		 * This barrier makes sure that the new value
1064 		 * of bfqg->entity.new_weight is correctly
1065 		 * seen in that code.
1066 		 */
1067 		smp_wmb();
1068 		bfqg->entity.prio_changed = 1;
1069 	}
1070 }
1071 
bfq_io_set_weight_legacy(struct cgroup_subsys_state * css,struct cftype * cftype,u64 val)1072 static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
1073 				    struct cftype *cftype,
1074 				    u64 val)
1075 {
1076 	struct blkcg *blkcg = css_to_blkcg(css);
1077 	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
1078 	struct blkcg_gq *blkg;
1079 	int ret = -ERANGE;
1080 
1081 	if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
1082 		return ret;
1083 
1084 	ret = 0;
1085 	spin_lock_irq(&blkcg->lock);
1086 	bfqgd->weight = (unsigned short)val;
1087 	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1088 		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
1089 
1090 		if (bfqg)
1091 			bfq_group_set_weight(bfqg, val, 0);
1092 	}
1093 	spin_unlock_irq(&blkcg->lock);
1094 
1095 	return ret;
1096 }
1097 
bfq_io_set_device_weight(struct kernfs_open_file * of,char * buf,size_t nbytes,loff_t off)1098 static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
1099 					char *buf, size_t nbytes,
1100 					loff_t off)
1101 {
1102 	int ret;
1103 	struct blkg_conf_ctx ctx;
1104 	struct blkcg *blkcg = css_to_blkcg(of_css(of));
1105 	struct bfq_group *bfqg;
1106 	u64 v;
1107 
1108 	blkg_conf_init(&ctx, buf);
1109 
1110 	ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, &ctx);
1111 	if (ret)
1112 		goto out;
1113 
1114 	if (sscanf(ctx.body, "%llu", &v) == 1) {
1115 		/* require "default" on dfl */
1116 		ret = -ERANGE;
1117 		if (!v)
1118 			goto out;
1119 	} else if (!strcmp(strim(ctx.body), "default")) {
1120 		v = 0;
1121 	} else {
1122 		ret = -EINVAL;
1123 		goto out;
1124 	}
1125 
1126 	bfqg = blkg_to_bfqg(ctx.blkg);
1127 
1128 	ret = -ERANGE;
1129 	if (!v || (v >= BFQ_MIN_WEIGHT && v <= BFQ_MAX_WEIGHT)) {
1130 		bfq_group_set_weight(bfqg, bfqg->entity.weight, v);
1131 		ret = 0;
1132 	}
1133 out:
1134 	blkg_conf_exit(&ctx);
1135 	return ret ?: nbytes;
1136 }
1137 
bfq_io_set_weight(struct kernfs_open_file * of,char * buf,size_t nbytes,loff_t off)1138 static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
1139 				 char *buf, size_t nbytes,
1140 				 loff_t off)
1141 {
1142 	char *endp;
1143 	int ret;
1144 	u64 v;
1145 
1146 	buf = strim(buf);
1147 
1148 	/* "WEIGHT" or "default WEIGHT" sets the default weight */
1149 	v = simple_strtoull(buf, &endp, 0);
1150 	if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
1151 		ret = bfq_io_set_weight_legacy(of_css(of), NULL, v);
1152 		return ret ?: nbytes;
1153 	}
1154 
1155 	return bfq_io_set_device_weight(of, buf, nbytes, off);
1156 }
1157 
bfqg_print_rwstat(struct seq_file * sf,void * v)1158 static int bfqg_print_rwstat(struct seq_file *sf, void *v)
1159 {
1160 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1161 			  &blkcg_policy_bfq, seq_cft(sf)->private, true);
1162 	return 0;
1163 }
1164 
bfqg_prfill_rwstat_recursive(struct seq_file * sf,struct blkg_policy_data * pd,int off)1165 static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
1166 					struct blkg_policy_data *pd, int off)
1167 {
1168 	struct blkg_rwstat_sample sum;
1169 
1170 	blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off, &sum);
1171 	return __blkg_prfill_rwstat(sf, pd, &sum);
1172 }
1173 
bfqg_print_rwstat_recursive(struct seq_file * sf,void * v)1174 static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1175 {
1176 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1177 			  bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
1178 			  seq_cft(sf)->private, true);
1179 	return 0;
1180 }
1181 
1182 #ifdef CONFIG_BFQ_CGROUP_DEBUG
bfqg_print_stat(struct seq_file * sf,void * v)1183 static int bfqg_print_stat(struct seq_file *sf, void *v)
1184 {
1185 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1186 			  &blkcg_policy_bfq, seq_cft(sf)->private, false);
1187 	return 0;
1188 }
1189 
bfqg_prfill_stat_recursive(struct seq_file * sf,struct blkg_policy_data * pd,int off)1190 static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
1191 				      struct blkg_policy_data *pd, int off)
1192 {
1193 	struct blkcg_gq *blkg = pd_to_blkg(pd);
1194 	struct blkcg_gq *pos_blkg;
1195 	struct cgroup_subsys_state *pos_css;
1196 	u64 sum = 0;
1197 
1198 	lockdep_assert_held(&blkg->q->queue_lock);
1199 
1200 	rcu_read_lock();
1201 	blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
1202 		struct bfq_stat *stat;
1203 
1204 		if (!pos_blkg->online)
1205 			continue;
1206 
1207 		stat = (void *)blkg_to_pd(pos_blkg, &blkcg_policy_bfq) + off;
1208 		sum += bfq_stat_read(stat) + atomic64_read(&stat->aux_cnt);
1209 	}
1210 	rcu_read_unlock();
1211 
1212 	return __blkg_prfill_u64(sf, pd, sum);
1213 }
1214 
bfqg_print_stat_recursive(struct seq_file * sf,void * v)1215 static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
1216 {
1217 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1218 			  bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
1219 			  seq_cft(sf)->private, false);
1220 	return 0;
1221 }
1222 
bfqg_prfill_sectors(struct seq_file * sf,struct blkg_policy_data * pd,int off)1223 static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
1224 			       int off)
1225 {
1226 	struct bfq_group *bfqg = blkg_to_bfqg(pd->blkg);
1227 	u64 sum = blkg_rwstat_total(&bfqg->stats.bytes);
1228 
1229 	return __blkg_prfill_u64(sf, pd, sum >> 9);
1230 }
1231 
bfqg_print_stat_sectors(struct seq_file * sf,void * v)1232 static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
1233 {
1234 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1235 			  bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
1236 	return 0;
1237 }
1238 
bfqg_prfill_sectors_recursive(struct seq_file * sf,struct blkg_policy_data * pd,int off)1239 static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
1240 					 struct blkg_policy_data *pd, int off)
1241 {
1242 	struct blkg_rwstat_sample tmp;
1243 
1244 	blkg_rwstat_recursive_sum(pd->blkg, &blkcg_policy_bfq,
1245 			offsetof(struct bfq_group, stats.bytes), &tmp);
1246 
1247 	return __blkg_prfill_u64(sf, pd,
1248 		(tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE]) >> 9);
1249 }
1250 
bfqg_print_stat_sectors_recursive(struct seq_file * sf,void * v)1251 static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
1252 {
1253 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1254 			  bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
1255 			  false);
1256 	return 0;
1257 }
1258 
bfqg_prfill_avg_queue_size(struct seq_file * sf,struct blkg_policy_data * pd,int off)1259 static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
1260 				      struct blkg_policy_data *pd, int off)
1261 {
1262 	struct bfq_group *bfqg = pd_to_bfqg(pd);
1263 	u64 samples = bfq_stat_read(&bfqg->stats.avg_queue_size_samples);
1264 	u64 v = 0;
1265 
1266 	if (samples) {
1267 		v = bfq_stat_read(&bfqg->stats.avg_queue_size_sum);
1268 		v = div64_u64(v, samples);
1269 	}
1270 	__blkg_prfill_u64(sf, pd, v);
1271 	return 0;
1272 }
1273 
1274 /* print avg_queue_size */
bfqg_print_avg_queue_size(struct seq_file * sf,void * v)1275 static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1276 {
1277 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1278 			  bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
1279 			  0, false);
1280 	return 0;
1281 }
1282 #endif /* CONFIG_BFQ_CGROUP_DEBUG */
1283 
bfq_create_group_hierarchy(struct bfq_data * bfqd,int node)1284 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
1285 {
1286 	int ret;
1287 
1288 	ret = blkcg_activate_policy(bfqd->queue->disk, &blkcg_policy_bfq);
1289 	if (ret)
1290 		return NULL;
1291 
1292 	return blkg_to_bfqg(bfqd->queue->root_blkg);
1293 }
1294 
1295 struct blkcg_policy blkcg_policy_bfq = {
1296 	.dfl_cftypes		= bfq_blkg_files,
1297 	.legacy_cftypes		= bfq_blkcg_legacy_files,
1298 
1299 	.cpd_alloc_fn		= bfq_cpd_alloc,
1300 	.cpd_free_fn		= bfq_cpd_free,
1301 
1302 	.pd_alloc_fn		= bfq_pd_alloc,
1303 	.pd_init_fn		= bfq_pd_init,
1304 	.pd_offline_fn		= bfq_pd_offline,
1305 	.pd_free_fn		= bfq_pd_free,
1306 	.pd_reset_stats_fn	= bfq_pd_reset_stats,
1307 };
1308 
1309 struct cftype bfq_blkcg_legacy_files[] = {
1310 	{
1311 		.name = "bfq.weight",
1312 		.flags = CFTYPE_NOT_ON_ROOT,
1313 		.seq_show = bfq_io_show_weight_legacy,
1314 		.write_u64 = bfq_io_set_weight_legacy,
1315 	},
1316 	{
1317 		.name = "bfq.weight_device",
1318 		.flags = CFTYPE_NOT_ON_ROOT,
1319 		.seq_show = bfq_io_show_weight,
1320 		.write = bfq_io_set_weight,
1321 	},
1322 
1323 	/* statistics, covers only the tasks in the bfqg */
1324 	{
1325 		.name = "bfq.io_service_bytes",
1326 		.private = offsetof(struct bfq_group, stats.bytes),
1327 		.seq_show = bfqg_print_rwstat,
1328 	},
1329 	{
1330 		.name = "bfq.io_serviced",
1331 		.private = offsetof(struct bfq_group, stats.ios),
1332 		.seq_show = bfqg_print_rwstat,
1333 	},
1334 #ifdef CONFIG_BFQ_CGROUP_DEBUG
1335 	{
1336 		.name = "bfq.time",
1337 		.private = offsetof(struct bfq_group, stats.time),
1338 		.seq_show = bfqg_print_stat,
1339 	},
1340 	{
1341 		.name = "bfq.sectors",
1342 		.seq_show = bfqg_print_stat_sectors,
1343 	},
1344 	{
1345 		.name = "bfq.io_service_time",
1346 		.private = offsetof(struct bfq_group, stats.service_time),
1347 		.seq_show = bfqg_print_rwstat,
1348 	},
1349 	{
1350 		.name = "bfq.io_wait_time",
1351 		.private = offsetof(struct bfq_group, stats.wait_time),
1352 		.seq_show = bfqg_print_rwstat,
1353 	},
1354 	{
1355 		.name = "bfq.io_merged",
1356 		.private = offsetof(struct bfq_group, stats.merged),
1357 		.seq_show = bfqg_print_rwstat,
1358 	},
1359 	{
1360 		.name = "bfq.io_queued",
1361 		.private = offsetof(struct bfq_group, stats.queued),
1362 		.seq_show = bfqg_print_rwstat,
1363 	},
1364 #endif /* CONFIG_BFQ_CGROUP_DEBUG */
1365 
1366 	/* the same statistics which cover the bfqg and its descendants */
1367 	{
1368 		.name = "bfq.io_service_bytes_recursive",
1369 		.private = offsetof(struct bfq_group, stats.bytes),
1370 		.seq_show = bfqg_print_rwstat_recursive,
1371 	},
1372 	{
1373 		.name = "bfq.io_serviced_recursive",
1374 		.private = offsetof(struct bfq_group, stats.ios),
1375 		.seq_show = bfqg_print_rwstat_recursive,
1376 	},
1377 #ifdef CONFIG_BFQ_CGROUP_DEBUG
1378 	{
1379 		.name = "bfq.time_recursive",
1380 		.private = offsetof(struct bfq_group, stats.time),
1381 		.seq_show = bfqg_print_stat_recursive,
1382 	},
1383 	{
1384 		.name = "bfq.sectors_recursive",
1385 		.seq_show = bfqg_print_stat_sectors_recursive,
1386 	},
1387 	{
1388 		.name = "bfq.io_service_time_recursive",
1389 		.private = offsetof(struct bfq_group, stats.service_time),
1390 		.seq_show = bfqg_print_rwstat_recursive,
1391 	},
1392 	{
1393 		.name = "bfq.io_wait_time_recursive",
1394 		.private = offsetof(struct bfq_group, stats.wait_time),
1395 		.seq_show = bfqg_print_rwstat_recursive,
1396 	},
1397 	{
1398 		.name = "bfq.io_merged_recursive",
1399 		.private = offsetof(struct bfq_group, stats.merged),
1400 		.seq_show = bfqg_print_rwstat_recursive,
1401 	},
1402 	{
1403 		.name = "bfq.io_queued_recursive",
1404 		.private = offsetof(struct bfq_group, stats.queued),
1405 		.seq_show = bfqg_print_rwstat_recursive,
1406 	},
1407 	{
1408 		.name = "bfq.avg_queue_size",
1409 		.seq_show = bfqg_print_avg_queue_size,
1410 	},
1411 	{
1412 		.name = "bfq.group_wait_time",
1413 		.private = offsetof(struct bfq_group, stats.group_wait_time),
1414 		.seq_show = bfqg_print_stat,
1415 	},
1416 	{
1417 		.name = "bfq.idle_time",
1418 		.private = offsetof(struct bfq_group, stats.idle_time),
1419 		.seq_show = bfqg_print_stat,
1420 	},
1421 	{
1422 		.name = "bfq.empty_time",
1423 		.private = offsetof(struct bfq_group, stats.empty_time),
1424 		.seq_show = bfqg_print_stat,
1425 	},
1426 	{
1427 		.name = "bfq.dequeue",
1428 		.private = offsetof(struct bfq_group, stats.dequeue),
1429 		.seq_show = bfqg_print_stat,
1430 	},
1431 #endif	/* CONFIG_BFQ_CGROUP_DEBUG */
1432 	{ }	/* terminate */
1433 };
1434 
1435 struct cftype bfq_blkg_files[] = {
1436 	{
1437 		.name = "bfq.weight",
1438 		.flags = CFTYPE_NOT_ON_ROOT,
1439 		.seq_show = bfq_io_show_weight,
1440 		.write = bfq_io_set_weight,
1441 	},
1442 	{} /* terminate */
1443 };
1444 
1445 #else	/* CONFIG_BFQ_GROUP_IOSCHED */
1446 
bfq_bfqq_move(struct bfq_data * bfqd,struct bfq_queue * bfqq,struct bfq_group * bfqg)1447 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1448 		   struct bfq_group *bfqg) {}
1449 
bfq_init_entity(struct bfq_entity * entity,struct bfq_group * bfqg)1450 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
1451 {
1452 	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
1453 
1454 	entity->weight = entity->new_weight;
1455 	entity->orig_weight = entity->new_weight;
1456 	if (bfqq) {
1457 		bfqq->ioprio = bfqq->new_ioprio;
1458 		bfqq->ioprio_class = bfqq->new_ioprio_class;
1459 	}
1460 	entity->sched_data = &bfqg->sched_data;
1461 }
1462 
bfq_bic_update_cgroup(struct bfq_io_cq * bic,struct bio * bio)1463 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {}
1464 
bfq_end_wr_async(struct bfq_data * bfqd)1465 void bfq_end_wr_async(struct bfq_data *bfqd)
1466 {
1467 	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
1468 }
1469 
bfq_bio_bfqg(struct bfq_data * bfqd,struct bio * bio)1470 struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio)
1471 {
1472 	return bfqd->root_group;
1473 }
1474 
bfqq_group(struct bfq_queue * bfqq)1475 struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
1476 {
1477 	return bfqq->bfqd->root_group;
1478 }
1479 
bfqg_and_blkg_put(struct bfq_group * bfqg)1480 void bfqg_and_blkg_put(struct bfq_group *bfqg) {}
1481 
bfq_create_group_hierarchy(struct bfq_data * bfqd,int node)1482 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
1483 {
1484 	struct bfq_group *bfqg;
1485 	int i;
1486 
1487 	bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
1488 	if (!bfqg)
1489 		return NULL;
1490 
1491 	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
1492 		bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
1493 
1494 	return bfqg;
1495 }
1496 #endif	/* CONFIG_BFQ_GROUP_IOSCHED */
1497