1 #ifndef _BLK_CGROUP_H
2 #define _BLK_CGROUP_H
3 /*
4 * Common Block IO controller cgroup interface
5 *
6 * Based on ideas and code from CFQ, CFS and BFQ:
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
8 *
9 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
10 * Paolo Valente <paolo.valente@unimore.it>
11 *
12 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
13 * Nauman Rafique <nauman@google.com>
14 */
15
16 #include <linux/cgroup.h>
17 #include <linux/u64_stats_sync.h>
18 #include <linux/seq_file.h>
19 #include <linux/radix-tree.h>
20 #include <linux/blkdev.h>
21 #include <linux/atomic.h>
22
23 /* Max limits for throttle policy */
24 #define THROTL_IOPS_MAX UINT_MAX
25
26 /* CFQ specific, out here for blkcg->cfq_weight */
27 #define CFQ_WEIGHT_MIN 10
28 #define CFQ_WEIGHT_MAX 1000
29 #define CFQ_WEIGHT_DEFAULT 500
30
31 #ifdef CONFIG_BLK_CGROUP
32
33 enum blkg_rwstat_type {
34 BLKG_RWSTAT_READ,
35 BLKG_RWSTAT_WRITE,
36 BLKG_RWSTAT_SYNC,
37 BLKG_RWSTAT_ASYNC,
38
39 BLKG_RWSTAT_NR,
40 BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
41 };
42
43 struct blkcg_gq;
44
45 struct blkcg {
46 struct cgroup_subsys_state css;
47 spinlock_t lock;
48
49 struct radix_tree_root blkg_tree;
50 struct blkcg_gq *blkg_hint;
51 struct hlist_head blkg_list;
52
53 /* TODO: per-policy storage in blkcg */
54 unsigned int cfq_weight; /* belongs to cfq */
55 unsigned int cfq_leaf_weight;
56 };
57
58 struct blkg_stat {
59 struct u64_stats_sync syncp;
60 uint64_t cnt;
61 };
62
63 struct blkg_rwstat {
64 struct u64_stats_sync syncp;
65 uint64_t cnt[BLKG_RWSTAT_NR];
66 };
67
68 /*
69 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
70 * request_queue (q). This is used by blkcg policies which need to track
71 * information per blkcg - q pair.
72 *
73 * There can be multiple active blkcg policies and each has its private
74 * data on each blkg, the size of which is determined by
75 * blkcg_policy->pd_size. blkcg core allocates and frees such areas
76 * together with blkg and invokes pd_init/exit_fn() methods.
77 *
78 * Such private data must embed struct blkg_policy_data (pd) at the
79 * beginning and pd_size can't be smaller than pd.
80 */
81 struct blkg_policy_data {
82 /* the blkg and policy id this per-policy data belongs to */
83 struct blkcg_gq *blkg;
84 int plid;
85
86 /* used during policy activation */
87 struct list_head alloc_node;
88 };
89
90 /* association between a blk cgroup and a request queue */
91 struct blkcg_gq {
92 /* Pointer to the associated request_queue */
93 struct request_queue *q;
94 struct list_head q_node;
95 struct hlist_node blkcg_node;
96 struct blkcg *blkcg;
97
98 /* all non-root blkcg_gq's are guaranteed to have access to parent */
99 struct blkcg_gq *parent;
100
101 /* request allocation list for this blkcg-q pair */
102 struct request_list rl;
103
104 /* reference count */
105 atomic_t refcnt;
106
107 /* is this blkg online? protected by both blkcg and q locks */
108 bool online;
109
110 struct blkg_policy_data *pd[BLKCG_MAX_POLS];
111
112 struct rcu_head rcu_head;
113 };
114
115 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
116 typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
117 typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
118 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
119 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
120
121 struct blkcg_policy {
122 int plid;
123 /* policy specific private data size */
124 size_t pd_size;
125 /* cgroup files for the policy */
126 struct cftype *cftypes;
127
128 /* operations */
129 blkcg_pol_init_pd_fn *pd_init_fn;
130 blkcg_pol_online_pd_fn *pd_online_fn;
131 blkcg_pol_offline_pd_fn *pd_offline_fn;
132 blkcg_pol_exit_pd_fn *pd_exit_fn;
133 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
134 };
135
136 extern struct blkcg blkcg_root;
137
138 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
139 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
140 struct request_queue *q);
141 int blkcg_init_queue(struct request_queue *q);
142 void blkcg_drain_queue(struct request_queue *q);
143 void blkcg_exit_queue(struct request_queue *q);
144
145 /* Blkio controller policy registration */
146 int blkcg_policy_register(struct blkcg_policy *pol);
147 void blkcg_policy_unregister(struct blkcg_policy *pol);
148 int blkcg_activate_policy(struct request_queue *q,
149 const struct blkcg_policy *pol);
150 void blkcg_deactivate_policy(struct request_queue *q,
151 const struct blkcg_policy *pol);
152
153 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
154 u64 (*prfill)(struct seq_file *,
155 struct blkg_policy_data *, int),
156 const struct blkcg_policy *pol, int data,
157 bool show_total);
158 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
159 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
160 const struct blkg_rwstat *rwstat);
161 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
162 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
163 int off);
164
165 u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
166 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
167 int off);
168
169 struct blkg_conf_ctx {
170 struct gendisk *disk;
171 struct blkcg_gq *blkg;
172 u64 v;
173 };
174
175 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
176 const char *input, struct blkg_conf_ctx *ctx);
177 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
178
179
css_to_blkcg(struct cgroup_subsys_state * css)180 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
181 {
182 return css ? container_of(css, struct blkcg, css) : NULL;
183 }
184
task_blkcg(struct task_struct * tsk)185 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
186 {
187 return css_to_blkcg(task_css(tsk, blkio_cgrp_id));
188 }
189
bio_blkcg(struct bio * bio)190 static inline struct blkcg *bio_blkcg(struct bio *bio)
191 {
192 if (bio && bio->bi_css)
193 return css_to_blkcg(bio->bi_css);
194 return task_blkcg(current);
195 }
196
197 /**
198 * blkcg_parent - get the parent of a blkcg
199 * @blkcg: blkcg of interest
200 *
201 * Return the parent blkcg of @blkcg. Can be called anytime.
202 */
blkcg_parent(struct blkcg * blkcg)203 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
204 {
205 return css_to_blkcg(blkcg->css.parent);
206 }
207
208 /**
209 * blkg_to_pdata - get policy private data
210 * @blkg: blkg of interest
211 * @pol: policy of interest
212 *
213 * Return pointer to private data associated with the @blkg-@pol pair.
214 */
blkg_to_pd(struct blkcg_gq * blkg,struct blkcg_policy * pol)215 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
216 struct blkcg_policy *pol)
217 {
218 return blkg ? blkg->pd[pol->plid] : NULL;
219 }
220
221 /**
222 * pdata_to_blkg - get blkg associated with policy private data
223 * @pd: policy private data of interest
224 *
225 * @pd is policy private data. Determine the blkg it's associated with.
226 */
pd_to_blkg(struct blkg_policy_data * pd)227 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
228 {
229 return pd ? pd->blkg : NULL;
230 }
231
232 /**
233 * blkg_path - format cgroup path of blkg
234 * @blkg: blkg of interest
235 * @buf: target buffer
236 * @buflen: target buffer length
237 *
238 * Format the path of the cgroup of @blkg into @buf.
239 */
blkg_path(struct blkcg_gq * blkg,char * buf,int buflen)240 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
241 {
242 char *p;
243
244 p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
245 if (!p) {
246 strncpy(buf, "<unavailable>", buflen);
247 return -ENAMETOOLONG;
248 }
249
250 memmove(buf, p, buf + buflen - p);
251 return 0;
252 }
253
254 /**
255 * blkg_get - get a blkg reference
256 * @blkg: blkg to get
257 *
258 * The caller should be holding an existing reference.
259 */
blkg_get(struct blkcg_gq * blkg)260 static inline void blkg_get(struct blkcg_gq *blkg)
261 {
262 WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
263 atomic_inc(&blkg->refcnt);
264 }
265
266 void __blkg_release_rcu(struct rcu_head *rcu);
267
268 /**
269 * blkg_put - put a blkg reference
270 * @blkg: blkg to put
271 */
blkg_put(struct blkcg_gq * blkg)272 static inline void blkg_put(struct blkcg_gq *blkg)
273 {
274 WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
275 if (atomic_dec_and_test(&blkg->refcnt))
276 call_rcu(&blkg->rcu_head, __blkg_release_rcu);
277 }
278
279 struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
280 bool update_hint);
281
282 /**
283 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
284 * @d_blkg: loop cursor pointing to the current descendant
285 * @pos_css: used for iteration
286 * @p_blkg: target blkg to walk descendants of
287 *
288 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
289 * read locked. If called under either blkcg or queue lock, the iteration
290 * is guaranteed to include all and only online blkgs. The caller may
291 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
292 * @p_blkg is included in the iteration and the first node to be visited.
293 */
294 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
295 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
296 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
297 (p_blkg)->q, false)))
298
299 /**
300 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
301 * @d_blkg: loop cursor pointing to the current descendant
302 * @pos_css: used for iteration
303 * @p_blkg: target blkg to walk descendants of
304 *
305 * Similar to blkg_for_each_descendant_pre() but performs post-order
306 * traversal instead. Synchronization rules are the same. @p_blkg is
307 * included in the iteration and the last node to be visited.
308 */
309 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
310 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
311 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
312 (p_blkg)->q, false)))
313
314 /**
315 * blk_get_rl - get request_list to use
316 * @q: request_queue of interest
317 * @bio: bio which will be attached to the allocated request (may be %NULL)
318 *
319 * The caller wants to allocate a request from @q to use for @bio. Find
320 * the request_list to use and obtain a reference on it. Should be called
321 * under queue_lock. This function is guaranteed to return non-%NULL
322 * request_list.
323 */
blk_get_rl(struct request_queue * q,struct bio * bio)324 static inline struct request_list *blk_get_rl(struct request_queue *q,
325 struct bio *bio)
326 {
327 struct blkcg *blkcg;
328 struct blkcg_gq *blkg;
329
330 rcu_read_lock();
331
332 blkcg = bio_blkcg(bio);
333
334 /* bypass blkg lookup and use @q->root_rl directly for root */
335 if (blkcg == &blkcg_root)
336 goto root_rl;
337
338 /*
339 * Try to use blkg->rl. blkg lookup may fail under memory pressure
340 * or if either the blkcg or queue is going away. Fall back to
341 * root_rl in such cases.
342 */
343 blkg = blkg_lookup_create(blkcg, q);
344 if (unlikely(IS_ERR(blkg)))
345 goto root_rl;
346
347 blkg_get(blkg);
348 rcu_read_unlock();
349 return &blkg->rl;
350 root_rl:
351 rcu_read_unlock();
352 return &q->root_rl;
353 }
354
355 /**
356 * blk_put_rl - put request_list
357 * @rl: request_list to put
358 *
359 * Put the reference acquired by blk_get_rl(). Should be called under
360 * queue_lock.
361 */
blk_put_rl(struct request_list * rl)362 static inline void blk_put_rl(struct request_list *rl)
363 {
364 /* root_rl may not have blkg set */
365 if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
366 blkg_put(rl->blkg);
367 }
368
369 /**
370 * blk_rq_set_rl - associate a request with a request_list
371 * @rq: request of interest
372 * @rl: target request_list
373 *
374 * Associate @rq with @rl so that accounting and freeing can know the
375 * request_list @rq came from.
376 */
blk_rq_set_rl(struct request * rq,struct request_list * rl)377 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
378 {
379 rq->rl = rl;
380 }
381
382 /**
383 * blk_rq_rl - return the request_list a request came from
384 * @rq: request of interest
385 *
386 * Return the request_list @rq is allocated from.
387 */
blk_rq_rl(struct request * rq)388 static inline struct request_list *blk_rq_rl(struct request *rq)
389 {
390 return rq->rl;
391 }
392
393 struct request_list *__blk_queue_next_rl(struct request_list *rl,
394 struct request_queue *q);
395 /**
396 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
397 *
398 * Should be used under queue_lock.
399 */
400 #define blk_queue_for_each_rl(rl, q) \
401 for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
402
blkg_stat_init(struct blkg_stat * stat)403 static inline void blkg_stat_init(struct blkg_stat *stat)
404 {
405 u64_stats_init(&stat->syncp);
406 }
407
408 /**
409 * blkg_stat_add - add a value to a blkg_stat
410 * @stat: target blkg_stat
411 * @val: value to add
412 *
413 * Add @val to @stat. The caller is responsible for synchronizing calls to
414 * this function.
415 */
blkg_stat_add(struct blkg_stat * stat,uint64_t val)416 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
417 {
418 u64_stats_update_begin(&stat->syncp);
419 stat->cnt += val;
420 u64_stats_update_end(&stat->syncp);
421 }
422
423 /**
424 * blkg_stat_read - read the current value of a blkg_stat
425 * @stat: blkg_stat to read
426 *
427 * Read the current value of @stat. This function can be called without
428 * synchroniztion and takes care of u64 atomicity.
429 */
blkg_stat_read(struct blkg_stat * stat)430 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
431 {
432 unsigned int start;
433 uint64_t v;
434
435 do {
436 start = u64_stats_fetch_begin_irq(&stat->syncp);
437 v = stat->cnt;
438 } while (u64_stats_fetch_retry_irq(&stat->syncp, start));
439
440 return v;
441 }
442
443 /**
444 * blkg_stat_reset - reset a blkg_stat
445 * @stat: blkg_stat to reset
446 */
blkg_stat_reset(struct blkg_stat * stat)447 static inline void blkg_stat_reset(struct blkg_stat *stat)
448 {
449 stat->cnt = 0;
450 }
451
452 /**
453 * blkg_stat_merge - merge a blkg_stat into another
454 * @to: the destination blkg_stat
455 * @from: the source
456 *
457 * Add @from's count to @to.
458 */
blkg_stat_merge(struct blkg_stat * to,struct blkg_stat * from)459 static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
460 {
461 blkg_stat_add(to, blkg_stat_read(from));
462 }
463
blkg_rwstat_init(struct blkg_rwstat * rwstat)464 static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
465 {
466 u64_stats_init(&rwstat->syncp);
467 }
468
469 /**
470 * blkg_rwstat_add - add a value to a blkg_rwstat
471 * @rwstat: target blkg_rwstat
472 * @rw: mask of REQ_{WRITE|SYNC}
473 * @val: value to add
474 *
475 * Add @val to @rwstat. The counters are chosen according to @rw. The
476 * caller is responsible for synchronizing calls to this function.
477 */
blkg_rwstat_add(struct blkg_rwstat * rwstat,int rw,uint64_t val)478 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
479 int rw, uint64_t val)
480 {
481 u64_stats_update_begin(&rwstat->syncp);
482
483 if (rw & REQ_WRITE)
484 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
485 else
486 rwstat->cnt[BLKG_RWSTAT_READ] += val;
487 if (rw & REQ_SYNC)
488 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
489 else
490 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
491
492 u64_stats_update_end(&rwstat->syncp);
493 }
494
495 /**
496 * blkg_rwstat_read - read the current values of a blkg_rwstat
497 * @rwstat: blkg_rwstat to read
498 *
499 * Read the current snapshot of @rwstat and return it as the return value.
500 * This function can be called without synchronization and takes care of
501 * u64 atomicity.
502 */
blkg_rwstat_read(struct blkg_rwstat * rwstat)503 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
504 {
505 unsigned int start;
506 struct blkg_rwstat tmp;
507
508 do {
509 start = u64_stats_fetch_begin_irq(&rwstat->syncp);
510 tmp = *rwstat;
511 } while (u64_stats_fetch_retry_irq(&rwstat->syncp, start));
512
513 return tmp;
514 }
515
516 /**
517 * blkg_rwstat_total - read the total count of a blkg_rwstat
518 * @rwstat: blkg_rwstat to read
519 *
520 * Return the total count of @rwstat regardless of the IO direction. This
521 * function can be called without synchronization and takes care of u64
522 * atomicity.
523 */
blkg_rwstat_total(struct blkg_rwstat * rwstat)524 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
525 {
526 struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
527
528 return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
529 }
530
531 /**
532 * blkg_rwstat_reset - reset a blkg_rwstat
533 * @rwstat: blkg_rwstat to reset
534 */
blkg_rwstat_reset(struct blkg_rwstat * rwstat)535 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
536 {
537 memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
538 }
539
540 /**
541 * blkg_rwstat_merge - merge a blkg_rwstat into another
542 * @to: the destination blkg_rwstat
543 * @from: the source
544 *
545 * Add @from's counts to @to.
546 */
blkg_rwstat_merge(struct blkg_rwstat * to,struct blkg_rwstat * from)547 static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
548 struct blkg_rwstat *from)
549 {
550 struct blkg_rwstat v = blkg_rwstat_read(from);
551 int i;
552
553 u64_stats_update_begin(&to->syncp);
554 for (i = 0; i < BLKG_RWSTAT_NR; i++)
555 to->cnt[i] += v.cnt[i];
556 u64_stats_update_end(&to->syncp);
557 }
558
559 #else /* CONFIG_BLK_CGROUP */
560
561 struct cgroup;
562 struct blkcg;
563
564 struct blkg_policy_data {
565 };
566
567 struct blkcg_gq {
568 };
569
570 struct blkcg_policy {
571 };
572
blkg_lookup(struct blkcg * blkcg,void * key)573 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
blkcg_init_queue(struct request_queue * q)574 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
blkcg_drain_queue(struct request_queue * q)575 static inline void blkcg_drain_queue(struct request_queue *q) { }
blkcg_exit_queue(struct request_queue * q)576 static inline void blkcg_exit_queue(struct request_queue *q) { }
blkcg_policy_register(struct blkcg_policy * pol)577 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
blkcg_policy_unregister(struct blkcg_policy * pol)578 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
blkcg_activate_policy(struct request_queue * q,const struct blkcg_policy * pol)579 static inline int blkcg_activate_policy(struct request_queue *q,
580 const struct blkcg_policy *pol) { return 0; }
blkcg_deactivate_policy(struct request_queue * q,const struct blkcg_policy * pol)581 static inline void blkcg_deactivate_policy(struct request_queue *q,
582 const struct blkcg_policy *pol) { }
583
bio_blkcg(struct bio * bio)584 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
585
blkg_to_pd(struct blkcg_gq * blkg,struct blkcg_policy * pol)586 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
587 struct blkcg_policy *pol) { return NULL; }
pd_to_blkg(struct blkg_policy_data * pd)588 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
blkg_path(struct blkcg_gq * blkg)589 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
blkg_get(struct blkcg_gq * blkg)590 static inline void blkg_get(struct blkcg_gq *blkg) { }
blkg_put(struct blkcg_gq * blkg)591 static inline void blkg_put(struct blkcg_gq *blkg) { }
592
blk_get_rl(struct request_queue * q,struct bio * bio)593 static inline struct request_list *blk_get_rl(struct request_queue *q,
594 struct bio *bio) { return &q->root_rl; }
blk_put_rl(struct request_list * rl)595 static inline void blk_put_rl(struct request_list *rl) { }
blk_rq_set_rl(struct request * rq,struct request_list * rl)596 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
blk_rq_rl(struct request * rq)597 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
598
599 #define blk_queue_for_each_rl(rl, q) \
600 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
601
602 #endif /* CONFIG_BLK_CGROUP */
603 #endif /* _BLK_CGROUP_H */
604