blk-cgroup.h

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