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Root/block/cfq-iosched.c

1	/*
2	* CFQ, or complete fairness queueing, disk scheduler.
3	*
4	* Based on ideas from a previously unfinished io
5	* scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
6	*
7	* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
8	*/
9	#include <linux/module.h>
10	#include <linux/slab.h>
11	#include <linux/blkdev.h>
12	#include <linux/elevator.h>
13	#include <linux/jiffies.h>
14	#include <linux/rbtree.h>
15	#include <linux/ioprio.h>
16	#include <linux/blktrace_api.h>
17	#include "blk.h"
18	#include "blk-cgroup.h"
19
20	/*
21	* tunables
22	*/
23	/* max queue in one round of service */
24	static const int cfq_quantum = 8;
25	static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
26	/* maximum backwards seek, in KiB */
27	static const int cfq_back_max = 16 * 1024;
28	/* penalty of a backwards seek */
29	static const int cfq_back_penalty = 2;
30	static const int cfq_slice_sync = HZ / 10;
31	static int cfq_slice_async = HZ / 25;
32	static const int cfq_slice_async_rq = 2;
33	static int cfq_slice_idle = HZ / 125;
34	static int cfq_group_idle = HZ / 125;
35	static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
36	static const int cfq_hist_divisor = 4;
37
38	/*
39	* offset from end of service tree
40	*/
41	#define CFQ_IDLE_DELAY (HZ / 5)
42
43	/*
44	* below this threshold, we consider thinktime immediate
45	*/
46	#define CFQ_MIN_TT (2)
47
48	#define CFQ_SLICE_SCALE (5)
49	#define CFQ_HW_QUEUE_MIN (5)
50	#define CFQ_SERVICE_SHIFT 12
51
52	#define CFQQ_SEEK_THR (sector_t)(8 * 100)
53	#define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54	#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55	#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
56
57	#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58	#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59	#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
60
61	static struct kmem_cache *cfq_pool;
62
63	#define CFQ_PRIO_LISTS IOPRIO_BE_NR
64	#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
65	#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
66
67	#define sample_valid(samples) ((samples) > 80)
68	#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
69
70	struct cfq_ttime {
71	unsigned long last_end_request;
72
73	unsigned long ttime_total;
74	unsigned long ttime_samples;
75	unsigned long ttime_mean;
76	};
77
78	/*
79	* Most of our rbtree usage is for sorting with min extraction, so
80	* if we cache the leftmost node we don't have to walk down the tree
81	* to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82	* move this into the elevator for the rq sorting as well.
83	*/
84	struct cfq_rb_root {
85	struct rb_root rb;
86	struct rb_node *left;
87	unsigned count;
88	u64 min_vdisktime;
89	struct cfq_ttime ttime;
90	};
91	#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
92	.ttime = {.last_end_request = jiffies,},}
93
94	/*
95	* Per process-grouping structure
96	*/
97	struct cfq_queue {
98	/* reference count */
99	int ref;
100	/* various state flags, see below */
101	unsigned int flags;
102	/* parent cfq_data */
103	struct cfq_data *cfqd;
104	/* service_tree member */
105	struct rb_node rb_node;
106	/* service_tree key */
107	unsigned long rb_key;
108	/* prio tree member */
109	struct rb_node p_node;
110	/* prio tree root we belong to, if any */
111	struct rb_root *p_root;
112	/* sorted list of pending requests */
113	struct rb_root sort_list;
114	/* if fifo isn't expired, next request to serve */
115	struct request *next_rq;
116	/* requests queued in sort_list */
117	int queued[2];
118	/* currently allocated requests */
119	int allocated[2];
120	/* fifo list of requests in sort_list */
121	struct list_head fifo;
122
123	/* time when queue got scheduled in to dispatch first request. */
124	unsigned long dispatch_start;
125	unsigned int allocated_slice;
126	unsigned int slice_dispatch;
127	/* time when first request from queue completed and slice started. */
128	unsigned long slice_start;
129	unsigned long slice_end;
130	long slice_resid;
131
132	/* pending priority requests */
133	int prio_pending;
134	/* number of requests that are on the dispatch list or inside driver */
135	int dispatched;
136
137	/* io prio of this group */
138	unsigned short ioprio, org_ioprio;
139	unsigned short ioprio_class;
140
141	pid_t pid;
142
143	u32 seek_history;
144	sector_t last_request_pos;
145
146	struct cfq_rb_root *service_tree;
147	struct cfq_queue *new_cfqq;
148	struct cfq_group *cfqg;
149	/* Number of sectors dispatched from queue in single dispatch round */
150	unsigned long nr_sectors;
151	};
152
153	/*
154	* First index in the service_trees.
155	* IDLE is handled separately, so it has negative index
156	*/
157	enum wl_class_t {
158	BE_WORKLOAD = 0,
159	RT_WORKLOAD = 1,
160	IDLE_WORKLOAD = 2,
161	CFQ_PRIO_NR,
162	};
163
164	/*
165	* Second index in the service_trees.
166	*/
167	enum wl_type_t {
168	ASYNC_WORKLOAD = 0,
169	SYNC_NOIDLE_WORKLOAD = 1,
170	SYNC_WORKLOAD = 2
171	};
172
173	struct cfqg_stats {
174	#ifdef CONFIG_CFQ_GROUP_IOSCHED
175	/* total bytes transferred */
176	struct blkg_rwstat service_bytes;
177	/* total IOs serviced, post merge */
178	struct blkg_rwstat serviced;
179	/* number of ios merged */
180	struct blkg_rwstat merged;
181	/* total time spent on device in ns, may not be accurate w/ queueing */
182	struct blkg_rwstat service_time;
183	/* total time spent waiting in scheduler queue in ns */
184	struct blkg_rwstat wait_time;
185	/* number of IOs queued up */
186	struct blkg_rwstat queued;
187	/* total sectors transferred */
188	struct blkg_stat sectors;
189	/* total disk time and nr sectors dispatched by this group */
190	struct blkg_stat time;
191	#ifdef CONFIG_DEBUG_BLK_CGROUP
192	/* time not charged to this cgroup */
193	struct blkg_stat unaccounted_time;
194	/* sum of number of ios queued across all samples */
195	struct blkg_stat avg_queue_size_sum;
196	/* count of samples taken for average */
197	struct blkg_stat avg_queue_size_samples;
198	/* how many times this group has been removed from service tree */
199	struct blkg_stat dequeue;
200	/* total time spent waiting for it to be assigned a timeslice. */
201	struct blkg_stat group_wait_time;
202	/* time spent idling for this blkcg_gq */
203	struct blkg_stat idle_time;
204	/* total time with empty current active q with other requests queued */
205	struct blkg_stat empty_time;
206	/* fields after this shouldn't be cleared on stat reset */
207	uint64_t start_group_wait_time;
208	uint64_t start_idle_time;
209	uint64_t start_empty_time;
210	uint16_t flags;
211	#endif /* CONFIG_DEBUG_BLK_CGROUP */
212	#endif /* CONFIG_CFQ_GROUP_IOSCHED */
213	};
214
215	/* This is per cgroup per device grouping structure */
216	struct cfq_group {
217	/* must be the first member */
218	struct blkg_policy_data pd;
219
220	/* group service_tree member */
221	struct rb_node rb_node;
222
223	/* group service_tree key */
224	u64 vdisktime;
225
226	/*
227	* The number of active cfqgs and sum of their weights under this
228	* cfqg. This covers this cfqg's leaf_weight and all children's
229	* weights, but does not cover weights of further descendants.
230	*
231	* If a cfqg is on the service tree, it's active. An active cfqg
232	* also activates its parent and contributes to the children_weight
233	* of the parent.
234	*/
235	int nr_active;
236	unsigned int children_weight;
237
238	/*
239	* vfraction is the fraction of vdisktime that the tasks in this
240	* cfqg are entitled to. This is determined by compounding the
241	* ratios walking up from this cfqg to the root.
242	*
243	* It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
244	* vfractions on a service tree is approximately 1. The sum may
245	* deviate a bit due to rounding errors and fluctuations caused by
246	* cfqgs entering and leaving the service tree.
247	*/
248	unsigned int vfraction;
249
250	/*
251	* There are two weights - (internal) weight is the weight of this
252	* cfqg against the sibling cfqgs. leaf_weight is the wight of
253	* this cfqg against the child cfqgs. For the root cfqg, both
254	* weights are kept in sync for backward compatibility.
255	*/
256	unsigned int weight;
257	unsigned int new_weight;
258	unsigned int dev_weight;
259
260	unsigned int leaf_weight;
261	unsigned int new_leaf_weight;
262	unsigned int dev_leaf_weight;
263
264	/* number of cfqq currently on this group */
265	int nr_cfqq;
266
267	/*
268	* Per group busy queues average. Useful for workload slice calc. We
269	* create the array for each prio class but at run time it is used
270	* only for RT and BE class and slot for IDLE class remains unused.
271	* This is primarily done to avoid confusion and a gcc warning.
272	*/
273	unsigned int busy_queues_avg[CFQ_PRIO_NR];
274	/*
275	* rr lists of queues with requests. We maintain service trees for
276	* RT and BE classes. These trees are subdivided in subclasses
277	* of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
278	* class there is no subclassification and all the cfq queues go on
279	* a single tree service_tree_idle.
280	* Counts are embedded in the cfq_rb_root
281	*/
282	struct cfq_rb_root service_trees[2][3];
283	struct cfq_rb_root service_tree_idle;
284
285	unsigned long saved_wl_slice;
286	enum wl_type_t saved_wl_type;
287	enum wl_class_t saved_wl_class;
288
289	/* number of requests that are on the dispatch list or inside driver */
290	int dispatched;
291	struct cfq_ttime ttime;
292	struct cfqg_stats stats; /* stats for this cfqg */
293	struct cfqg_stats dead_stats; /* stats pushed from dead children */
294	};
295
296	struct cfq_io_cq {
297	struct io_cq icq; /* must be the first member */
298	struct cfq_queue *cfqq[2];
299	struct cfq_ttime ttime;
300	int ioprio; /* the current ioprio */
301	#ifdef CONFIG_CFQ_GROUP_IOSCHED
302	uint64_t blkcg_id; /* the current blkcg ID */
303	#endif
304	};
305
306	/*
307	* Per block device queue structure
308	*/
309	struct cfq_data {
310	struct request_queue *queue;
311	/* Root service tree for cfq_groups */
312	struct cfq_rb_root grp_service_tree;
313	struct cfq_group *root_group;
314
315	/*
316	* The priority currently being served
317	*/
318	enum wl_class_t serving_wl_class;
319	enum wl_type_t serving_wl_type;
320	unsigned long workload_expires;
321	struct cfq_group *serving_group;
322
323	/*
324	* Each priority tree is sorted by next_request position. These
325	* trees are used when determining if two or more queues are
326	* interleaving requests (see cfq_close_cooperator).
327	*/
328	struct rb_root prio_trees[CFQ_PRIO_LISTS];
329
330	unsigned int busy_queues;
331	unsigned int busy_sync_queues;
332
333	int rq_in_driver;
334	int rq_in_flight[2];
335
336	/*
337	* queue-depth detection
338	*/
339	int rq_queued;
340	int hw_tag;
341	/*
342	* hw_tag can be
343	* -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
344	* 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
345	* 0 => no NCQ
346	*/
347	int hw_tag_est_depth;
348	unsigned int hw_tag_samples;
349
350	/*
351	* idle window management
352	*/
353	struct timer_list idle_slice_timer;
354	struct work_struct unplug_work;
355
356	struct cfq_queue *active_queue;
357	struct cfq_io_cq *active_cic;
358
359	/*
360	* async queue for each priority case
361	*/
362	struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
363	struct cfq_queue *async_idle_cfqq;
364
365	sector_t last_position;
366
367	/*
368	* tunables, see top of file
369	*/
370	unsigned int cfq_quantum;
371	unsigned int cfq_fifo_expire[2];
372	unsigned int cfq_back_penalty;
373	unsigned int cfq_back_max;
374	unsigned int cfq_slice[2];
375	unsigned int cfq_slice_async_rq;
376	unsigned int cfq_slice_idle;
377	unsigned int cfq_group_idle;
378	unsigned int cfq_latency;
379	unsigned int cfq_target_latency;
380
381	/*
382	* Fallback dummy cfqq for extreme OOM conditions
383	*/
384	struct cfq_queue oom_cfqq;
385
386	unsigned long last_delayed_sync;
387	};
388
389	static struct cfq_group cfq_get_next_cfqg(struct cfq_data cfqd);
390
391	static struct cfq_rb_root st_for(struct cfq_group cfqg,
392	enum wl_class_t class,
393	enum wl_type_t type)
394	{
395	if (!cfqg)
396	return NULL;
397
398	if (class == IDLE_WORKLOAD)
399	return &cfqg->service_tree_idle;
400
401	return &cfqg->service_trees[class][type];
402	}
403
404	enum cfqq_state_flags {
405	CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
406	CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
407	CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
408	CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
409	CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
410	CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
411	CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
412	CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
413	CFQ_CFQQ_FLAG_sync, /* synchronous queue */
414	CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
415	CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
416	CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
417	CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
418	};
419
420	#define CFQ_CFQQ_FNS(name) \
421	static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
422	{ \
423	(cfqq)->flags \|= (1 << CFQ_CFQQ_FLAG_##name); \
424	} \
425	static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
426	{ \
427	(cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
428	} \
429	static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
430	{ \
431	return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
432	}
433
434	CFQ_CFQQ_FNS(on_rr);
435	CFQ_CFQQ_FNS(wait_request);
436	CFQ_CFQQ_FNS(must_dispatch);
437	CFQ_CFQQ_FNS(must_alloc_slice);
438	CFQ_CFQQ_FNS(fifo_expire);
439	CFQ_CFQQ_FNS(idle_window);
440	CFQ_CFQQ_FNS(prio_changed);
441	CFQ_CFQQ_FNS(slice_new);
442	CFQ_CFQQ_FNS(sync);
443	CFQ_CFQQ_FNS(coop);
444	CFQ_CFQQ_FNS(split_coop);
445	CFQ_CFQQ_FNS(deep);
446	CFQ_CFQQ_FNS(wait_busy);
447	#undef CFQ_CFQQ_FNS
448
449	static inline struct cfq_group pd_to_cfqg(struct blkg_policy_data pd)
450	{
451	return pd ? container_of(pd, struct cfq_group, pd) : NULL;
452	}
453
454	static inline struct blkcg_gq cfqg_to_blkg(struct cfq_group cfqg)
455	{
456	return pd_to_blkg(&cfqg->pd);
457	}
458
459	#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
460
461	/* cfqg stats flags */
462	enum cfqg_stats_flags {
463	CFQG_stats_waiting = 0,
464	CFQG_stats_idling,
465	CFQG_stats_empty,
466	};
467
468	#define CFQG_FLAG_FNS(name) \
469	static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
470	{ \
471	stats->flags \|= (1 << CFQG_stats_##name); \
472	} \
473	static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
474	{ \
475	stats->flags &= ~(1 << CFQG_stats_##name); \
476	} \
477	static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
478	{ \
479	return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
480	} \
481
482	CFQG_FLAG_FNS(waiting)
483	CFQG_FLAG_FNS(idling)
484	CFQG_FLAG_FNS(empty)
485	#undef CFQG_FLAG_FNS
486
487	/* This should be called with the queue_lock held. */
488	static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
489	{
490	unsigned long long now;
491
492	if (!cfqg_stats_waiting(stats))
493	return;
494
495	now = sched_clock();
496	if (time_after64(now, stats->start_group_wait_time))
497	blkg_stat_add(&stats->group_wait_time,
498	now - stats->start_group_wait_time);
499	cfqg_stats_clear_waiting(stats);
500	}
501
502	/* This should be called with the queue_lock held. */
503	static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
504	struct cfq_group *curr_cfqg)
505	{
506	struct cfqg_stats *stats = &cfqg->stats;
507
508	if (cfqg_stats_waiting(stats))
509	return;
510	if (cfqg == curr_cfqg)
511	return;
512	stats->start_group_wait_time = sched_clock();
513	cfqg_stats_mark_waiting(stats);
514	}
515
516	/* This should be called with the queue_lock held. */
517	static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
518	{
519	unsigned long long now;
520
521	if (!cfqg_stats_empty(stats))
522	return;
523
524	now = sched_clock();
525	if (time_after64(now, stats->start_empty_time))
526	blkg_stat_add(&stats->empty_time,
527	now - stats->start_empty_time);
528	cfqg_stats_clear_empty(stats);
529	}
530
531	static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
532	{
533	blkg_stat_add(&cfqg->stats.dequeue, 1);
534	}
535
536	static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
537	{
538	struct cfqg_stats *stats = &cfqg->stats;
539
540	if (blkg_rwstat_total(&stats->queued))
541	return;
542
543	/*
544	* group is already marked empty. This can happen if cfqq got new
545	* request in parent group and moved to this group while being added
546	* to service tree. Just ignore the event and move on.
547	*/
548	if (cfqg_stats_empty(stats))
549	return;
550
551	stats->start_empty_time = sched_clock();
552	cfqg_stats_mark_empty(stats);
553	}
554
555	static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
556	{
557	struct cfqg_stats *stats = &cfqg->stats;
558
559	if (cfqg_stats_idling(stats)) {
560	unsigned long long now = sched_clock();
561
562	if (time_after64(now, stats->start_idle_time))
563	blkg_stat_add(&stats->idle_time,
564	now - stats->start_idle_time);
565	cfqg_stats_clear_idling(stats);
566	}
567	}
568
569	static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
570	{
571	struct cfqg_stats *stats = &cfqg->stats;
572
573	BUG_ON(cfqg_stats_idling(stats));
574
575	stats->start_idle_time = sched_clock();
576	cfqg_stats_mark_idling(stats);
577	}
578
579	static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
580	{
581	struct cfqg_stats *stats = &cfqg->stats;
582
583	blkg_stat_add(&stats->avg_queue_size_sum,
584	blkg_rwstat_total(&stats->queued));
585	blkg_stat_add(&stats->avg_queue_size_samples, 1);
586	cfqg_stats_update_group_wait_time(stats);
587	}
588
589	#else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
590
591	static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group cfqg, struct cfq_group curr_cfqg) { }
592	static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
593	static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
594	static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
595	static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
596	static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
597	static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
598
599	#endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
600
601	#ifdef CONFIG_CFQ_GROUP_IOSCHED
602
603	static struct blkcg_policy blkcg_policy_cfq;
604
605	static inline struct cfq_group blkg_to_cfqg(struct blkcg_gq blkg)
606	{
607	return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
608	}
609
610	static inline struct cfq_group cfqg_parent(struct cfq_group cfqg)
611	{
612	struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
613
614	return pblkg ? blkg_to_cfqg(pblkg) : NULL;
615	}
616
617	static inline void cfqg_get(struct cfq_group *cfqg)
618	{
619	return blkg_get(cfqg_to_blkg(cfqg));
620	}
621
622	static inline void cfqg_put(struct cfq_group *cfqg)
623	{
624	return blkg_put(cfqg_to_blkg(cfqg));
625	}
626
627	#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
628	char __pbuf[128]; \
629	\
630	blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
631	blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
632	cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
633	cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
634	__pbuf, ##args); \
635	} while (0)
636
637	#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
638	char __pbuf[128]; \
639	\
640	blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
641	blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
642	} while (0)
643
644	static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
645	struct cfq_group *curr_cfqg, int rw)
646	{
647	blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
648	cfqg_stats_end_empty_time(&cfqg->stats);
649	cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
650	}
651
652	static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
653	unsigned long time, unsigned long unaccounted_time)
654	{
655	blkg_stat_add(&cfqg->stats.time, time);
656	#ifdef CONFIG_DEBUG_BLK_CGROUP
657	blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
658	#endif
659	}
660
661	static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
662	{
663	blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
664	}
665
666	static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
667	{
668	blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
669	}
670
671	static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
672	uint64_t bytes, int rw)
673	{
674	blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
675	blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
676	blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
677	}
678
679	static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
680	uint64_t start_time, uint64_t io_start_time, int rw)
681	{
682	struct cfqg_stats *stats = &cfqg->stats;
683	unsigned long long now = sched_clock();
684
685	if (time_after64(now, io_start_time))
686	blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
687	if (time_after64(io_start_time, start_time))
688	blkg_rwstat_add(&stats->wait_time, rw,
689	io_start_time - start_time);
690	}
691
692	/* @stats = 0 */
693	static void cfqg_stats_reset(struct cfqg_stats *stats)
694	{
695	/* queued stats shouldn't be cleared */
696	blkg_rwstat_reset(&stats->service_bytes);
697	blkg_rwstat_reset(&stats->serviced);
698	blkg_rwstat_reset(&stats->merged);
699	blkg_rwstat_reset(&stats->service_time);
700	blkg_rwstat_reset(&stats->wait_time);
701	blkg_stat_reset(&stats->time);
702	#ifdef CONFIG_DEBUG_BLK_CGROUP
703	blkg_stat_reset(&stats->unaccounted_time);
704	blkg_stat_reset(&stats->avg_queue_size_sum);
705	blkg_stat_reset(&stats->avg_queue_size_samples);
706	blkg_stat_reset(&stats->dequeue);
707	blkg_stat_reset(&stats->group_wait_time);
708	blkg_stat_reset(&stats->idle_time);
709	blkg_stat_reset(&stats->empty_time);
710	#endif
711	}
712
713	/* @to += @from */
714	static void cfqg_stats_merge(struct cfqg_stats to, struct cfqg_stats from)
715	{
716	/* queued stats shouldn't be cleared */
717	blkg_rwstat_merge(&to->service_bytes, &from->service_bytes);
718	blkg_rwstat_merge(&to->serviced, &from->serviced);
719	blkg_rwstat_merge(&to->merged, &from->merged);
720	blkg_rwstat_merge(&to->service_time, &from->service_time);
721	blkg_rwstat_merge(&to->wait_time, &from->wait_time);
722	blkg_stat_merge(&from->time, &from->time);
723	#ifdef CONFIG_DEBUG_BLK_CGROUP
724	blkg_stat_merge(&to->unaccounted_time, &from->unaccounted_time);
725	blkg_stat_merge(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
726	blkg_stat_merge(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
727	blkg_stat_merge(&to->dequeue, &from->dequeue);
728	blkg_stat_merge(&to->group_wait_time, &from->group_wait_time);
729	blkg_stat_merge(&to->idle_time, &from->idle_time);
730	blkg_stat_merge(&to->empty_time, &from->empty_time);
731	#endif
732	}
733
734	/*
735	* Transfer @cfqg's stats to its parent's dead_stats so that the ancestors'
736	* recursive stats can still account for the amount used by this cfqg after
737	* it's gone.
738	*/
739	static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
740	{
741	struct cfq_group *parent = cfqg_parent(cfqg);
742
743	lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
744
745	if (unlikely(!parent))
746	return;
747
748	cfqg_stats_merge(&parent->dead_stats, &cfqg->stats);
749	cfqg_stats_merge(&parent->dead_stats, &cfqg->dead_stats);
750	cfqg_stats_reset(&cfqg->stats);
751	cfqg_stats_reset(&cfqg->dead_stats);
752	}
753
754	#else /* CONFIG_CFQ_GROUP_IOSCHED */
755
756	static inline struct cfq_group cfqg_parent(struct cfq_group cfqg) { return NULL; }
757	static inline void cfqg_get(struct cfq_group *cfqg) { }
758	static inline void cfqg_put(struct cfq_group *cfqg) { }
759
760	#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
761	blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
762	cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
763	cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
764	##args)
765	#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
766
767	static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
768	struct cfq_group *curr_cfqg, int rw) { }
769	static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
770	unsigned long time, unsigned long unaccounted_time) { }
771	static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
772	static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
773	static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
774	uint64_t bytes, int rw) { }
775	static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
776	uint64_t start_time, uint64_t io_start_time, int rw) { }
777
778	#endif /* CONFIG_CFQ_GROUP_IOSCHED */
779
780	#define cfq_log(cfqd, fmt, args...) \
781	blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
782
783	/* Traverses through cfq group service trees */
784	#define for_each_cfqg_st(cfqg, i, j, st) \
785	for (i = 0; i <= IDLE_WORKLOAD; i++) \
786	for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
787	: &cfqg->service_tree_idle; \
788	(i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) \|\| \
789	(i == IDLE_WORKLOAD && j == 0); \
790	j++, st = i < IDLE_WORKLOAD ? \
791	&cfqg->service_trees[i][j]: NULL) \
792
793	static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
794	struct cfq_ttime *ttime, bool group_idle)
795	{
796	unsigned long slice;
797	if (!sample_valid(ttime->ttime_samples))
798	return false;
799	if (group_idle)
800	slice = cfqd->cfq_group_idle;
801	else
802	slice = cfqd->cfq_slice_idle;
803	return ttime->ttime_mean > slice;
804	}
805
806	static inline bool iops_mode(struct cfq_data *cfqd)
807	{
808	/*
809	* If we are not idling on queues and it is a NCQ drive, parallel
810	* execution of requests is on and measuring time is not possible
811	* in most of the cases until and unless we drive shallower queue
812	* depths and that becomes a performance bottleneck. In such cases
813	* switch to start providing fairness in terms of number of IOs.
814	*/
815	if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
816	return true;
817	else
818	return false;
819	}
820
821	static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
822	{
823	if (cfq_class_idle(cfqq))
824	return IDLE_WORKLOAD;
825	if (cfq_class_rt(cfqq))
826	return RT_WORKLOAD;
827	return BE_WORKLOAD;
828	}
829
830
831	static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
832	{
833	if (!cfq_cfqq_sync(cfqq))
834	return ASYNC_WORKLOAD;
835	if (!cfq_cfqq_idle_window(cfqq))
836	return SYNC_NOIDLE_WORKLOAD;
837	return SYNC_WORKLOAD;
838	}
839
840	static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
841	struct cfq_data *cfqd,
842	struct cfq_group *cfqg)
843	{
844	if (wl_class == IDLE_WORKLOAD)
845	return cfqg->service_tree_idle.count;
846
847	return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
848	cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
849	cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
850	}
851
852	static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
853	struct cfq_group *cfqg)
854	{
855	return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
856	cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
857	}
858
859	static void cfq_dispatch_insert(struct request_queue , struct request );
860	static struct cfq_queue cfq_get_queue(struct cfq_data cfqd, bool is_sync,
861	struct cfq_io_cq cic, struct bio bio,
862	gfp_t gfp_mask);
863
864	static inline struct cfq_io_cq icq_to_cic(struct io_cq icq)
865	{
866	/* cic->icq is the first member, %NULL will convert to %NULL */
867	return container_of(icq, struct cfq_io_cq, icq);
868	}
869
870	static inline struct cfq_io_cq cfq_cic_lookup(struct cfq_data cfqd,
871	struct io_context *ioc)
872	{
873	if (ioc)
874	return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
875	return NULL;
876	}
877
878	static inline struct cfq_queue cic_to_cfqq(struct cfq_io_cq cic, bool is_sync)
879	{
880	return cic->cfqq[is_sync];
881	}
882
883	static inline void cic_set_cfqq(struct cfq_io_cq cic, struct cfq_queue cfqq,
884	bool is_sync)
885	{
886	cic->cfqq[is_sync] = cfqq;
887	}
888
889	static inline struct cfq_data cic_to_cfqd(struct cfq_io_cq cic)
890	{
891	return cic->icq.q->elevator->elevator_data;
892	}
893
894	/*
895	* We regard a request as SYNC, if it's either a read or has the SYNC bit
896	* set (in which case it could also be direct WRITE).
897	*/
898	static inline bool cfq_bio_sync(struct bio *bio)
899	{
900	return bio_data_dir(bio) == READ \|\| (bio->bi_rw & REQ_SYNC);
901	}
902
903	/*
904	* scheduler run of queue, if there are requests pending and no one in the
905	* driver that will restart queueing
906	*/
907	static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
908	{
909	if (cfqd->busy_queues) {
910	cfq_log(cfqd, "schedule dispatch");
911	kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
912	}
913	}
914
915	/*
916	* Scale schedule slice based on io priority. Use the sync time slice only
917	* if a queue is marked sync and has sync io queued. A sync queue with async
918	* io only, should not get full sync slice length.
919	*/
920	static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
921	unsigned short prio)
922	{
923	const int base_slice = cfqd->cfq_slice[sync];
924
925	WARN_ON(prio >= IOPRIO_BE_NR);
926
927	return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
928	}
929
930	static inline int
931	cfq_prio_to_slice(struct cfq_data cfqd, struct cfq_queue cfqq)
932	{
933	return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
934	}
935
936	/**
937	* cfqg_scale_charge - scale disk time charge according to cfqg weight
938	* @charge: disk time being charged
939	* @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
940	*
941	* Scale @charge according to @vfraction, which is in range (0, 1]. The
942	* scaling is inversely proportional.
943	*
944	* scaled = charge / vfraction
945	*
946	* The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
947	*/
948	static inline u64 cfqg_scale_charge(unsigned long charge,
949	unsigned int vfraction)
950	{
951	u64 c = charge << CFQ_SERVICE_SHIFT; /* make it fixed point */
952
953	/* charge / vfraction */
954	c <<= CFQ_SERVICE_SHIFT;
955	do_div(c, vfraction);
956	return c;
957	}
958
959	static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
960	{
961	s64 delta = (s64)(vdisktime - min_vdisktime);
962	if (delta > 0)
963	min_vdisktime = vdisktime;
964
965	return min_vdisktime;
966	}
967
968	static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
969	{
970	s64 delta = (s64)(vdisktime - min_vdisktime);
971	if (delta < 0)
972	min_vdisktime = vdisktime;
973
974	return min_vdisktime;
975	}
976
977	static void update_min_vdisktime(struct cfq_rb_root *st)
978	{
979	struct cfq_group *cfqg;
980
981	if (st->left) {
982	cfqg = rb_entry_cfqg(st->left);
983	st->min_vdisktime = max_vdisktime(st->min_vdisktime,
984	cfqg->vdisktime);
985	}
986	}
987
988	/*
989	* get averaged number of queues of RT/BE priority.
990	* average is updated, with a formula that gives more weight to higher numbers,
991	* to quickly follows sudden increases and decrease slowly
992	*/
993
994	static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
995	struct cfq_group *cfqg, bool rt)
996	{
997	unsigned min_q, max_q;
998	unsigned mult = cfq_hist_divisor - 1;
999	unsigned round = cfq_hist_divisor / 2;
1000	unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
1001
1002	min_q = min(cfqg->busy_queues_avg[rt], busy);
1003	max_q = max(cfqg->busy_queues_avg[rt], busy);
1004	cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
1005	cfq_hist_divisor;
1006	return cfqg->busy_queues_avg[rt];
1007	}
1008
1009	static inline unsigned
1010	cfq_group_slice(struct cfq_data cfqd, struct cfq_group cfqg)
1011	{
1012	return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
1013	}
1014
1015	static inline unsigned
1016	cfq_scaled_cfqq_slice(struct cfq_data cfqd, struct cfq_queue cfqq)
1017	{
1018	unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
1019	if (cfqd->cfq_latency) {
1020	/*
1021	* interested queues (we consider only the ones with the same
1022	* priority class in the cfq group)
1023	*/
1024	unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
1025	cfq_class_rt(cfqq));
1026	unsigned sync_slice = cfqd->cfq_slice[1];
1027	unsigned expect_latency = sync_slice * iq;
1028	unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
1029
1030	if (expect_latency > group_slice) {
1031	unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
1032	/* scale low_slice according to IO priority
1033	* and sync vs async */
1034	unsigned low_slice =
1035	min(slice, base_low_slice * slice / sync_slice);
1036	/* the adapted slice value is scaled to fit all iqs
1037	* into the target latency */
1038	slice = max(slice * group_slice / expect_latency,
1039	low_slice);
1040	}
1041	}
1042	return slice;
1043	}
1044
1045	static inline void
1046	cfq_set_prio_slice(struct cfq_data cfqd, struct cfq_queue cfqq)
1047	{
1048	unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
1049
1050	cfqq->slice_start = jiffies;
1051	cfqq->slice_end = jiffies + slice;
1052	cfqq->allocated_slice = slice;
1053	cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
1054	}
1055
1056	/*
1057	* We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1058	* isn't valid until the first request from the dispatch is activated
1059	* and the slice time set.
1060	*/
1061	static inline bool cfq_slice_used(struct cfq_queue *cfqq)
1062	{
1063	if (cfq_cfqq_slice_new(cfqq))
1064	return false;
1065	if (time_before(jiffies, cfqq->slice_end))
1066	return false;
1067
1068	return true;
1069	}
1070
1071	/*
1072	* Lifted from AS - choose which of rq1 and rq2 that is best served now.
1073	* We choose the request that is closest to the head right now. Distance
1074	* behind the head is penalized and only allowed to a certain extent.
1075	*/
1076	static struct request *
1077	cfq_choose_req(struct cfq_data cfqd, struct request rq1, struct request *rq2, sector_t last)
1078	{
1079	sector_t s1, s2, d1 = 0, d2 = 0;
1080	unsigned long back_max;
1081	#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
1082	#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
1083	unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1084
1085	if (rq1 == NULL \|\| rq1 == rq2)
1086	return rq2;
1087	if (rq2 == NULL)
1088	return rq1;
1089
1090	if (rq_is_sync(rq1) != rq_is_sync(rq2))
1091	return rq_is_sync(rq1) ? rq1 : rq2;
1092
1093	if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
1094	return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
1095
1096	s1 = blk_rq_pos(rq1);
1097	s2 = blk_rq_pos(rq2);
1098
1099	/*
1100	* by definition, 1KiB is 2 sectors
1101	*/
1102	back_max = cfqd->cfq_back_max * 2;
1103
1104	/*
1105	* Strict one way elevator _except_ in the case where we allow
1106	* short backward seeks which are biased as twice the cost of a
1107	* similar forward seek.
1108	*/
1109	if (s1 >= last)
1110	d1 = s1 - last;
1111	else if (s1 + back_max >= last)
1112	d1 = (last - s1) * cfqd->cfq_back_penalty;
1113	else
1114	wrap \|= CFQ_RQ1_WRAP;
1115
1116	if (s2 >= last)
1117	d2 = s2 - last;
1118	else if (s2 + back_max >= last)
1119	d2 = (last - s2) * cfqd->cfq_back_penalty;
1120	else
1121	wrap \|= CFQ_RQ2_WRAP;
1122
1123	/* Found required data */
1124
1125	/*
1126	* By doing switch() on the bit mask "wrap" we avoid having to
1127	* check two variables for all permutations: --> faster!
1128	*/
1129	switch (wrap) {
1130	case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1131	if (d1 < d2)
1132	return rq1;
1133	else if (d2 < d1)
1134	return rq2;
1135	else {
1136	if (s1 >= s2)
1137	return rq1;
1138	else
1139	return rq2;
1140	}
1141
1142	case CFQ_RQ2_WRAP:
1143	return rq1;
1144	case CFQ_RQ1_WRAP:
1145	return rq2;
1146	case (CFQ_RQ1_WRAP\|CFQ_RQ2_WRAP): /* both rqs wrapped */
1147	default:
1148	/*
1149	* Since both rqs are wrapped,
1150	* start with the one that's further behind head
1151	* (--> only one back seek required),
1152	* since back seek takes more time than forward.
1153	*/
1154	if (s1 <= s2)
1155	return rq1;
1156	else
1157	return rq2;
1158	}
1159	}
1160
1161	/*
1162	* The below is leftmost cache rbtree addon
1163	*/
1164	static struct cfq_queue cfq_rb_first(struct cfq_rb_root root)
1165	{
1166	/* Service tree is empty */
1167	if (!root->count)
1168	return NULL;
1169
1170	if (!root->left)
1171	root->left = rb_first(&root->rb);
1172
1173	if (root->left)
1174	return rb_entry(root->left, struct cfq_queue, rb_node);
1175
1176	return NULL;
1177	}
1178
1179	static struct cfq_group cfq_rb_first_group(struct cfq_rb_root root)
1180	{
1181	if (!root->left)
1182	root->left = rb_first(&root->rb);
1183
1184	if (root->left)
1185	return rb_entry_cfqg(root->left);
1186
1187	return NULL;
1188	}
1189
1190	static void rb_erase_init(struct rb_node n, struct rb_root root)
1191	{
1192	rb_erase(n, root);
1193	RB_CLEAR_NODE(n);
1194	}
1195
1196	static void cfq_rb_erase(struct rb_node n, struct cfq_rb_root root)
1197	{
1198	if (root->left == n)
1199	root->left = NULL;
1200	rb_erase_init(n, &root->rb);
1201	--root->count;
1202	}
1203
1204	/*
1205	* would be nice to take fifo expire time into account as well
1206	*/
1207	static struct request *
1208	cfq_find_next_rq(struct cfq_data cfqd, struct cfq_queue cfqq,
1209	struct request *last)
1210	{
1211	struct rb_node *rbnext = rb_next(&last->rb_node);
1212	struct rb_node *rbprev = rb_prev(&last->rb_node);
1213	struct request next = NULL, prev = NULL;
1214
1215	BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1216
1217	if (rbprev)
1218	prev = rb_entry_rq(rbprev);
1219
1220	if (rbnext)
1221	next = rb_entry_rq(rbnext);
1222	else {
1223	rbnext = rb_first(&cfqq->sort_list);
1224	if (rbnext && rbnext != &last->rb_node)
1225	next = rb_entry_rq(rbnext);
1226	}
1227
1228	return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1229	}
1230
1231	static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1232	struct cfq_queue *cfqq)
1233	{
1234	/*
1235	* just an approximation, should be ok.
1236	*/
1237	return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1238	cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1239	}
1240
1241	static inline s64
1242	cfqg_key(struct cfq_rb_root st, struct cfq_group cfqg)
1243	{
1244	return cfqg->vdisktime - st->min_vdisktime;
1245	}
1246
1247	static void
1248	__cfq_group_service_tree_add(struct cfq_rb_root st, struct cfq_group cfqg)
1249	{
1250	struct rb_node **node = &st->rb.rb_node;
1251	struct rb_node *parent = NULL;
1252	struct cfq_group *__cfqg;
1253	s64 key = cfqg_key(st, cfqg);
1254	int left = 1;
1255
1256	while (*node != NULL) {
1257	parent = *node;
1258	__cfqg = rb_entry_cfqg(parent);
1259
1260	if (key < cfqg_key(st, __cfqg))
1261	node = &parent->rb_left;
1262	else {
1263	node = &parent->rb_right;
1264	left = 0;
1265	}
1266	}
1267
1268	if (left)
1269	st->left = &cfqg->rb_node;
1270
1271	rb_link_node(&cfqg->rb_node, parent, node);
1272	rb_insert_color(&cfqg->rb_node, &st->rb);
1273	}
1274
1275	static void
1276	cfq_update_group_weight(struct cfq_group *cfqg)
1277	{
1278	BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1279
1280	if (cfqg->new_weight) {
1281	cfqg->weight = cfqg->new_weight;
1282	cfqg->new_weight = 0;
1283	}
1284
1285	if (cfqg->new_leaf_weight) {
1286	cfqg->leaf_weight = cfqg->new_leaf_weight;
1287	cfqg->new_leaf_weight = 0;
1288	}
1289	}
1290
1291	static void
1292	cfq_group_service_tree_add(struct cfq_rb_root st, struct cfq_group cfqg)
1293	{
1294	unsigned int vfr = 1 << CFQ_SERVICE_SHIFT; /* start with 1 */
1295	struct cfq_group *pos = cfqg;
1296	struct cfq_group *parent;
1297	bool propagate;
1298
1299	/* add to the service tree */
1300	BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1301
1302	cfq_update_group_weight(cfqg);
1303	__cfq_group_service_tree_add(st, cfqg);
1304
1305	/*
1306	* Activate @cfqg and calculate the portion of vfraction @cfqg is
1307	* entitled to. vfraction is calculated by walking the tree
1308	* towards the root calculating the fraction it has at each level.
1309	* The compounded ratio is how much vfraction @cfqg owns.
1310	*
1311	* Start with the proportion tasks in this cfqg has against active
1312	* children cfqgs - its leaf_weight against children_weight.
1313	*/
1314	propagate = !pos->nr_active++;
1315	pos->children_weight += pos->leaf_weight;
1316	vfr = vfr * pos->leaf_weight / pos->children_weight;
1317
1318	/*
1319	* Compound ->weight walking up the tree. Both activation and
1320	* vfraction calculation are done in the same loop. Propagation
1321	* stops once an already activated node is met. vfraction
1322	* calculation should always continue to the root.
1323	*/
1324	while ((parent = cfqg_parent(pos))) {
1325	if (propagate) {
1326	propagate = !parent->nr_active++;
1327	parent->children_weight += pos->weight;
1328	}
1329	vfr = vfr * pos->weight / parent->children_weight;
1330	pos = parent;
1331	}
1332
1333	cfqg->vfraction = max_t(unsigned, vfr, 1);
1334	}
1335
1336	static void
1337	cfq_group_notify_queue_add(struct cfq_data cfqd, struct cfq_group cfqg)
1338	{
1339	struct cfq_rb_root *st = &cfqd->grp_service_tree;
1340	struct cfq_group *__cfqg;
1341	struct rb_node *n;
1342
1343	cfqg->nr_cfqq++;
1344	if (!RB_EMPTY_NODE(&cfqg->rb_node))
1345	return;
1346
1347	/*
1348	* Currently put the group at the end. Later implement something
1349	* so that groups get lesser vtime based on their weights, so that
1350	* if group does not loose all if it was not continuously backlogged.
1351	*/
1352	n = rb_last(&st->rb);
1353	if (n) {
1354	__cfqg = rb_entry_cfqg(n);
1355	cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1356	} else
1357	cfqg->vdisktime = st->min_vdisktime;
1358	cfq_group_service_tree_add(st, cfqg);
1359	}
1360
1361	static void
1362	cfq_group_service_tree_del(struct cfq_rb_root st, struct cfq_group cfqg)
1363	{
1364	struct cfq_group *pos = cfqg;
1365	bool propagate;
1366
1367	/*
1368	* Undo activation from cfq_group_service_tree_add(). Deactivate
1369	* @cfqg and propagate deactivation upwards.
1370	*/
1371	propagate = !--pos->nr_active;
1372	pos->children_weight -= pos->leaf_weight;
1373
1374	while (propagate) {
1375	struct cfq_group *parent = cfqg_parent(pos);
1376
1377	/* @pos has 0 nr_active at this point */
1378	WARN_ON_ONCE(pos->children_weight);
1379	pos->vfraction = 0;
1380
1381	if (!parent)
1382	break;
1383
1384	propagate = !--parent->nr_active;
1385	parent->children_weight -= pos->weight;
1386	pos = parent;
1387	}
1388
1389	/* remove from the service tree */
1390	if (!RB_EMPTY_NODE(&cfqg->rb_node))
1391	cfq_rb_erase(&cfqg->rb_node, st);
1392	}
1393
1394	static void
1395	cfq_group_notify_queue_del(struct cfq_data cfqd, struct cfq_group cfqg)
1396	{
1397	struct cfq_rb_root *st = &cfqd->grp_service_tree;
1398
1399	BUG_ON(cfqg->nr_cfqq < 1);
1400	cfqg->nr_cfqq--;
1401
1402	/* If there are other cfq queues under this group, don't delete it */
1403	if (cfqg->nr_cfqq)
1404	return;
1405
1406	cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1407	cfq_group_service_tree_del(st, cfqg);
1408	cfqg->saved_wl_slice = 0;
1409	cfqg_stats_update_dequeue(cfqg);
1410	}
1411
1412	static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1413	unsigned int *unaccounted_time)
1414	{
1415	unsigned int slice_used;
1416
1417	/*
1418	* Queue got expired before even a single request completed or
1419	* got expired immediately after first request completion.
1420	*/
1421	if (!cfqq->slice_start \|\| cfqq->slice_start == jiffies) {
1422	/*
1423	* Also charge the seek time incurred to the group, otherwise
1424	* if there are mutiple queues in the group, each can dispatch
1425	* a single request on seeky media and cause lots of seek time
1426	* and group will never know it.
1427	*/
1428	slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1429	1);
1430	} else {
1431	slice_used = jiffies - cfqq->slice_start;
1432	if (slice_used > cfqq->allocated_slice) {
1433	*unaccounted_time = slice_used - cfqq->allocated_slice;
1434	slice_used = cfqq->allocated_slice;
1435	}
1436	if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1437	*unaccounted_time += cfqq->slice_start -
1438	cfqq->dispatch_start;
1439	}
1440
1441	return slice_used;
1442	}
1443
1444	static void cfq_group_served(struct cfq_data cfqd, struct cfq_group cfqg,
1445	struct cfq_queue *cfqq)
1446	{
1447	struct cfq_rb_root *st = &cfqd->grp_service_tree;
1448	unsigned int used_sl, charge, unaccounted_sl = 0;
1449	int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1450	- cfqg->service_tree_idle.count;
1451	unsigned int vfr;
1452
1453	BUG_ON(nr_sync < 0);
1454	used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1455
1456	if (iops_mode(cfqd))
1457	charge = cfqq->slice_dispatch;
1458	else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1459	charge = cfqq->allocated_slice;
1460
1461	/*
1462	* Can't update vdisktime while on service tree and cfqg->vfraction
1463	* is valid only while on it. Cache vfr, leave the service tree,
1464	* update vdisktime and go back on. The re-addition to the tree
1465	* will also update the weights as necessary.
1466	*/
1467	vfr = cfqg->vfraction;
1468	cfq_group_service_tree_del(st, cfqg);
1469	cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
1470	cfq_group_service_tree_add(st, cfqg);
1471
1472	/* This group is being expired. Save the context */
1473	if (time_after(cfqd->workload_expires, jiffies)) {
1474	cfqg->saved_wl_slice = cfqd->workload_expires
1475	- jiffies;
1476	cfqg->saved_wl_type = cfqd->serving_wl_type;
1477	cfqg->saved_wl_class = cfqd->serving_wl_class;
1478	} else
1479	cfqg->saved_wl_slice = 0;
1480
1481	cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1482	st->min_vdisktime);
1483	cfq_log_cfqq(cfqq->cfqd, cfqq,
1484	"sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1485	used_sl, cfqq->slice_dispatch, charge,
1486	iops_mode(cfqd), cfqq->nr_sectors);
1487	cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1488	cfqg_stats_set_start_empty_time(cfqg);
1489	}
1490
1491	/**
1492	* cfq_init_cfqg_base - initialize base part of a cfq_group
1493	* @cfqg: cfq_group to initialize
1494	*
1495	* Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1496	* is enabled or not.
1497	*/
1498	static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1499	{
1500	struct cfq_rb_root *st;
1501	int i, j;
1502
1503	for_each_cfqg_st(cfqg, i, j, st)
1504	*st = CFQ_RB_ROOT;
1505	RB_CLEAR_NODE(&cfqg->rb_node);
1506
1507	cfqg->ttime.last_end_request = jiffies;
1508	}
1509
1510	#ifdef CONFIG_CFQ_GROUP_IOSCHED
1511	static void cfq_pd_init(struct blkcg_gq *blkg)
1512	{
1513	struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1514
1515	cfq_init_cfqg_base(cfqg);
1516	cfqg->weight = blkg->blkcg->cfq_weight;
1517	cfqg->leaf_weight = blkg->blkcg->cfq_leaf_weight;
1518	}
1519
1520	static void cfq_pd_offline(struct blkcg_gq *blkg)
1521	{
1522	/*
1523	* @blkg is going offline and will be ignored by
1524	* blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
1525	* that they don't get lost. If IOs complete after this point, the
1526	* stats for them will be lost. Oh well...
1527	*/
1528	cfqg_stats_xfer_dead(blkg_to_cfqg(blkg));
1529	}
1530
1531	/* offset delta from cfqg->stats to cfqg->dead_stats */
1532	static const int dead_stats_off_delta = offsetof(struct cfq_group, dead_stats) -
1533	offsetof(struct cfq_group, stats);
1534
1535	/* to be used by recursive prfill, sums live and dead stats recursively */
1536	static u64 cfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off)
1537	{
1538	u64 sum = 0;
1539
1540	sum += blkg_stat_recursive_sum(pd, off);
1541	sum += blkg_stat_recursive_sum(pd, off + dead_stats_off_delta);
1542	return sum;
1543	}
1544
1545	/* to be used by recursive prfill, sums live and dead rwstats recursively */
1546	static struct blkg_rwstat cfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd,
1547	int off)
1548	{
1549	struct blkg_rwstat a, b;
1550
1551	a = blkg_rwstat_recursive_sum(pd, off);
1552	b = blkg_rwstat_recursive_sum(pd, off + dead_stats_off_delta);
1553	blkg_rwstat_merge(&a, &b);
1554	return a;
1555	}
1556
1557	static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
1558	{
1559	struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1560
1561	cfqg_stats_reset(&cfqg->stats);
1562	cfqg_stats_reset(&cfqg->dead_stats);
1563	}
1564
1565	/*
1566	* Search for the cfq group current task belongs to. request_queue lock must
1567	* be held.
1568	*/
1569	static struct cfq_group cfq_lookup_create_cfqg(struct cfq_data cfqd,
1570	struct blkcg *blkcg)
1571	{
1572	struct request_queue *q = cfqd->queue;
1573	struct cfq_group *cfqg = NULL;
1574
1575	/* avoid lookup for the common case where there's no blkcg */
1576	if (blkcg == &blkcg_root) {
1577	cfqg = cfqd->root_group;
1578	} else {
1579	struct blkcg_gq *blkg;
1580
1581	blkg = blkg_lookup_create(blkcg, q);
1582	if (!IS_ERR(blkg))
1583	cfqg = blkg_to_cfqg(blkg);
1584	}
1585
1586	return cfqg;
1587	}
1588
1589	static void cfq_link_cfqq_cfqg(struct cfq_queue cfqq, struct cfq_group cfqg)
1590	{
1591	/* Currently, all async queues are mapped to root group */
1592	if (!cfq_cfqq_sync(cfqq))
1593	cfqg = cfqq->cfqd->root_group;
1594
1595	cfqq->cfqg = cfqg;
1596	/* cfqq reference on cfqg */
1597	cfqg_get(cfqg);
1598	}
1599
1600	static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1601	struct blkg_policy_data *pd, int off)
1602	{
1603	struct cfq_group *cfqg = pd_to_cfqg(pd);
1604
1605	if (!cfqg->dev_weight)
1606	return 0;
1607	return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1608	}
1609
1610	static int cfqg_print_weight_device(struct cgroup cgrp, struct cftype cft,
1611	struct seq_file *sf)
1612	{
1613	blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp),
1614	cfqg_prfill_weight_device, &blkcg_policy_cfq, 0,
1615	false);
1616	return 0;
1617	}
1618
1619	static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1620	struct blkg_policy_data *pd, int off)
1621	{
1622	struct cfq_group *cfqg = pd_to_cfqg(pd);
1623
1624	if (!cfqg->dev_leaf_weight)
1625	return 0;
1626	return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1627	}
1628
1629	static int cfqg_print_leaf_weight_device(struct cgroup *cgrp,
1630	struct cftype *cft,
1631	struct seq_file *sf)
1632	{
1633	blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp),
1634	cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq, 0,
1635	false);
1636	return 0;
1637	}
1638
1639	static int cfq_print_weight(struct cgroup cgrp, struct cftype cft,
1640	struct seq_file *sf)
1641	{
1642	seq_printf(sf, "%u\n", cgroup_to_blkcg(cgrp)->cfq_weight);
1643	return 0;
1644	}
1645
1646	static int cfq_print_leaf_weight(struct cgroup cgrp, struct cftype cft,
1647	struct seq_file *sf)
1648	{
1649	seq_printf(sf, "%u\n",
1650	cgroup_to_blkcg(cgrp)->cfq_leaf_weight);
1651	return 0;
1652	}
1653
1654	static int __cfqg_set_weight_device(struct cgroup cgrp, struct cftype cft,
1655	const char *buf, bool is_leaf_weight)
1656	{
1657	struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1658	struct blkg_conf_ctx ctx;
1659	struct cfq_group *cfqg;
1660	int ret;
1661
1662	ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1663	if (ret)
1664	return ret;
1665
1666	ret = -EINVAL;
1667	cfqg = blkg_to_cfqg(ctx.blkg);
1668	if (!ctx.v \|\| (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1669	if (!is_leaf_weight) {
1670	cfqg->dev_weight = ctx.v;
1671	cfqg->new_weight = ctx.v ?: blkcg->cfq_weight;
1672	} else {
1673	cfqg->dev_leaf_weight = ctx.v;
1674	cfqg->new_leaf_weight = ctx.v ?: blkcg->cfq_leaf_weight;
1675	}
1676	ret = 0;
1677	}
1678
1679	blkg_conf_finish(&ctx);
1680	return ret;
1681	}
1682
1683	static int cfqg_set_weight_device(struct cgroup cgrp, struct cftype cft,
1684	const char *buf)
1685	{
1686	return __cfqg_set_weight_device(cgrp, cft, buf, false);
1687	}
1688
1689	static int cfqg_set_leaf_weight_device(struct cgroup cgrp, struct cftype cft,
1690	const char *buf)
1691	{
1692	return __cfqg_set_weight_device(cgrp, cft, buf, true);
1693	}
1694
1695	static int __cfq_set_weight(struct cgroup cgrp, struct cftype cft, u64 val,
1696	bool is_leaf_weight)
1697	{
1698	struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1699	struct blkcg_gq *blkg;
1700
1701	if (val < CFQ_WEIGHT_MIN \|\| val > CFQ_WEIGHT_MAX)
1702	return -EINVAL;
1703
1704	spin_lock_irq(&blkcg->lock);
1705
1706	if (!is_leaf_weight)
1707	blkcg->cfq_weight = val;
1708	else
1709	blkcg->cfq_leaf_weight = val;
1710
1711	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1712	struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1713
1714	if (!cfqg)
1715	continue;
1716
1717	if (!is_leaf_weight) {
1718	if (!cfqg->dev_weight)
1719	cfqg->new_weight = blkcg->cfq_weight;
1720	} else {
1721	if (!cfqg->dev_leaf_weight)
1722	cfqg->new_leaf_weight = blkcg->cfq_leaf_weight;
1723	}
1724	}
1725
1726	spin_unlock_irq(&blkcg->lock);
1727	return 0;
1728	}
1729
1730	static int cfq_set_weight(struct cgroup cgrp, struct cftype cft, u64 val)
1731	{
1732	return __cfq_set_weight(cgrp, cft, val, false);
1733	}
1734
1735	static int cfq_set_leaf_weight(struct cgroup cgrp, struct cftype cft, u64 val)
1736	{
1737	return __cfq_set_weight(cgrp, cft, val, true);
1738	}
1739
1740	static int cfqg_print_stat(struct cgroup cgrp, struct cftype cft,
1741	struct seq_file *sf)
1742	{
1743	struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1744
1745	blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq,
1746	cft->private, false);
1747	return 0;
1748	}
1749
1750	static int cfqg_print_rwstat(struct cgroup cgrp, struct cftype cft,
1751	struct seq_file *sf)
1752	{
1753	struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1754
1755	blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq,
1756	cft->private, true);
1757	return 0;
1758	}
1759
1760	static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1761	struct blkg_policy_data *pd, int off)
1762	{
1763	u64 sum = cfqg_stat_pd_recursive_sum(pd, off);
1764
1765	return __blkg_prfill_u64(sf, pd, sum);
1766	}
1767
1768	static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1769	struct blkg_policy_data *pd, int off)
1770	{
1771	struct blkg_rwstat sum = cfqg_rwstat_pd_recursive_sum(pd, off);
1772
1773	return __blkg_prfill_rwstat(sf, pd, &sum);
1774	}
1775
1776	static int cfqg_print_stat_recursive(struct cgroup cgrp, struct cftype cft,
1777	struct seq_file *sf)
1778	{
1779	struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1780
1781	blkcg_print_blkgs(sf, blkcg, cfqg_prfill_stat_recursive,
1782	&blkcg_policy_cfq, cft->private, false);
1783	return 0;
1784	}
1785
1786	static int cfqg_print_rwstat_recursive(struct cgroup cgrp, struct cftype cft,
1787	struct seq_file *sf)
1788	{
1789	struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1790
1791	blkcg_print_blkgs(sf, blkcg, cfqg_prfill_rwstat_recursive,
1792	&blkcg_policy_cfq, cft->private, true);
1793	return 0;
1794	}
1795
1796	#ifdef CONFIG_DEBUG_BLK_CGROUP
1797	static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1798	struct blkg_policy_data *pd, int off)
1799	{
1800	struct cfq_group *cfqg = pd_to_cfqg(pd);
1801	u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1802	u64 v = 0;
1803
1804	if (samples) {
1805	v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1806	do_div(v, samples);
1807	}
1808	__blkg_prfill_u64(sf, pd, v);
1809	return 0;
1810	}
1811
1812	/* print avg_queue_size */
1813	static int cfqg_print_avg_queue_size(struct cgroup cgrp, struct cftype cft,
1814	struct seq_file *sf)
1815	{
1816	struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1817
1818	blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size,
1819	&blkcg_policy_cfq, 0, false);
1820	return 0;
1821	}
1822	#endif /* CONFIG_DEBUG_BLK_CGROUP */
1823
1824	static struct cftype cfq_blkcg_files[] = {
1825	/* on root, weight is mapped to leaf_weight */
1826	{
1827	.name = "weight_device",
1828	.flags = CFTYPE_ONLY_ON_ROOT,
1829	.read_seq_string = cfqg_print_leaf_weight_device,
1830	.write_string = cfqg_set_leaf_weight_device,
1831	.max_write_len = 256,
1832	},
1833	{
1834	.name = "weight",
1835	.flags = CFTYPE_ONLY_ON_ROOT,
1836	.read_seq_string = cfq_print_leaf_weight,
1837	.write_u64 = cfq_set_leaf_weight,
1838	},
1839
1840	/* no such mapping necessary for !roots */
1841	{
1842	.name = "weight_device",
1843	.flags = CFTYPE_NOT_ON_ROOT,
1844	.read_seq_string = cfqg_print_weight_device,
1845	.write_string = cfqg_set_weight_device,
1846	.max_write_len = 256,
1847	},
1848	{
1849	.name = "weight",
1850	.flags = CFTYPE_NOT_ON_ROOT,
1851	.read_seq_string = cfq_print_weight,
1852	.write_u64 = cfq_set_weight,
1853	},
1854
1855	{
1856	.name = "leaf_weight_device",
1857	.read_seq_string = cfqg_print_leaf_weight_device,
1858	.write_string = cfqg_set_leaf_weight_device,
1859	.max_write_len = 256,
1860	},
1861	{
1862	.name = "leaf_weight",
1863	.read_seq_string = cfq_print_leaf_weight,
1864	.write_u64 = cfq_set_leaf_weight,
1865	},
1866
1867	/* statistics, covers only the tasks in the cfqg */
1868	{
1869	.name = "time",
1870	.private = offsetof(struct cfq_group, stats.time),
1871	.read_seq_string = cfqg_print_stat,
1872	},
1873	{
1874	.name = "sectors",
1875	.private = offsetof(struct cfq_group, stats.sectors),
1876	.read_seq_string = cfqg_print_stat,
1877	},
1878	{
1879	.name = "io_service_bytes",
1880	.private = offsetof(struct cfq_group, stats.service_bytes),
1881	.read_seq_string = cfqg_print_rwstat,
1882	},
1883	{
1884	.name = "io_serviced",
1885	.private = offsetof(struct cfq_group, stats.serviced),
1886	.read_seq_string = cfqg_print_rwstat,
1887	},
1888	{
1889	.name = "io_service_time",
1890	.private = offsetof(struct cfq_group, stats.service_time),
1891	.read_seq_string = cfqg_print_rwstat,
1892	},
1893	{
1894	.name = "io_wait_time",
1895	.private = offsetof(struct cfq_group, stats.wait_time),
1896	.read_seq_string = cfqg_print_rwstat,
1897	},
1898	{
1899	.name = "io_merged",
1900	.private = offsetof(struct cfq_group, stats.merged),
1901	.read_seq_string = cfqg_print_rwstat,
1902	},
1903	{
1904	.name = "io_queued",
1905	.private = offsetof(struct cfq_group, stats.queued),
1906	.read_seq_string = cfqg_print_rwstat,
1907	},
1908
1909	/* the same statictics which cover the cfqg and its descendants */
1910	{
1911	.name = "time_recursive",
1912	.private = offsetof(struct cfq_group, stats.time),
1913	.read_seq_string = cfqg_print_stat_recursive,
1914	},
1915	{
1916	.name = "sectors_recursive",
1917	.private = offsetof(struct cfq_group, stats.sectors),
1918	.read_seq_string = cfqg_print_stat_recursive,
1919	},
1920	{
1921	.name = "io_service_bytes_recursive",
1922	.private = offsetof(struct cfq_group, stats.service_bytes),
1923	.read_seq_string = cfqg_print_rwstat_recursive,
1924	},
1925	{
1926	.name = "io_serviced_recursive",
1927	.private = offsetof(struct cfq_group, stats.serviced),
1928	.read_seq_string = cfqg_print_rwstat_recursive,
1929	},
1930	{
1931	.name = "io_service_time_recursive",
1932	.private = offsetof(struct cfq_group, stats.service_time),
1933	.read_seq_string = cfqg_print_rwstat_recursive,
1934	},
1935	{
1936	.name = "io_wait_time_recursive",
1937	.private = offsetof(struct cfq_group, stats.wait_time),
1938	.read_seq_string = cfqg_print_rwstat_recursive,
1939	},
1940	{
1941	.name = "io_merged_recursive",
1942	.private = offsetof(struct cfq_group, stats.merged),
1943	.read_seq_string = cfqg_print_rwstat_recursive,
1944	},
1945	{
1946	.name = "io_queued_recursive",
1947	.private = offsetof(struct cfq_group, stats.queued),
1948	.read_seq_string = cfqg_print_rwstat_recursive,
1949	},
1950	#ifdef CONFIG_DEBUG_BLK_CGROUP
1951	{
1952	.name = "avg_queue_size",
1953	.read_seq_string = cfqg_print_avg_queue_size,
1954	},
1955	{
1956	.name = "group_wait_time",
1957	.private = offsetof(struct cfq_group, stats.group_wait_time),
1958	.read_seq_string = cfqg_print_stat,
1959	},
1960	{
1961	.name = "idle_time",
1962	.private = offsetof(struct cfq_group, stats.idle_time),
1963	.read_seq_string = cfqg_print_stat,
1964	},
1965	{
1966	.name = "empty_time",
1967	.private = offsetof(struct cfq_group, stats.empty_time),
1968	.read_seq_string = cfqg_print_stat,
1969	},
1970	{
1971	.name = "dequeue",
1972	.private = offsetof(struct cfq_group, stats.dequeue),
1973	.read_seq_string = cfqg_print_stat,
1974	},
1975	{
1976	.name = "unaccounted_time",
1977	.private = offsetof(struct cfq_group, stats.unaccounted_time),
1978	.read_seq_string = cfqg_print_stat,
1979	},
1980	#endif /* CONFIG_DEBUG_BLK_CGROUP */
1981	{ } /* terminate */
1982	};
1983	#else /* GROUP_IOSCHED */
1984	static struct cfq_group cfq_lookup_create_cfqg(struct cfq_data cfqd,
1985	struct blkcg *blkcg)
1986	{
1987	return cfqd->root_group;
1988	}
1989
1990	static inline void
1991	cfq_link_cfqq_cfqg(struct cfq_queue cfqq, struct cfq_group cfqg) {
1992	cfqq->cfqg = cfqg;
1993	}
1994
1995	#endif /* GROUP_IOSCHED */
1996
1997	/*
1998	* The cfqd->service_trees holds all pending cfq_queue's that have
1999	* requests waiting to be processed. It is sorted in the order that
2000	* we will service the queues.
2001	*/
2002	static void cfq_service_tree_add(struct cfq_data cfqd, struct cfq_queue cfqq,
2003	bool add_front)
2004	{
2005	struct rb_node *p, parent;
2006	struct cfq_queue *__cfqq;
2007	unsigned long rb_key;
2008	struct cfq_rb_root *st;
2009	int left;
2010	int new_cfqq = 1;
2011
2012	st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2013	if (cfq_class_idle(cfqq)) {
2014	rb_key = CFQ_IDLE_DELAY;
2015	parent = rb_last(&st->rb);
2016	if (parent && parent != &cfqq->rb_node) {
2017	__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2018	rb_key += __cfqq->rb_key;
2019	} else
2020	rb_key += jiffies;
2021	} else if (!add_front) {
2022	/*
2023	* Get our rb key offset. Subtract any residual slice
2024	* value carried from last service. A negative resid
2025	* count indicates slice overrun, and this should position
2026	* the next service time further away in the tree.
2027	*/
2028	rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
2029	rb_key -= cfqq->slice_resid;
2030	cfqq->slice_resid = 0;
2031	} else {
2032	rb_key = -HZ;
2033	__cfqq = cfq_rb_first(st);
2034	rb_key += __cfqq ? __cfqq->rb_key : jiffies;
2035	}
2036
2037	if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2038	new_cfqq = 0;
2039	/*
2040	* same position, nothing more to do
2041	*/
2042	if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2043	return;
2044
2045	cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2046	cfqq->service_tree = NULL;
2047	}
2048
2049	left = 1;
2050	parent = NULL;
2051	cfqq->service_tree = st;
2052	p = &st->rb.rb_node;
2053	while (*p) {
2054	parent = *p;
2055	__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2056
2057	/*
2058	* sort by key, that represents service time.
2059	*/
2060	if (time_before(rb_key, __cfqq->rb_key))
2061	p = &parent->rb_left;
2062	else {
2063	p = &parent->rb_right;
2064	left = 0;
2065	}
2066	}
2067
2068	if (left)
2069	st->left = &cfqq->rb_node;
2070
2071	cfqq->rb_key = rb_key;
2072	rb_link_node(&cfqq->rb_node, parent, p);
2073	rb_insert_color(&cfqq->rb_node, &st->rb);
2074	st->count++;
2075	if (add_front \|\| !new_cfqq)
2076	return;
2077	cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2078	}
2079
2080	static struct cfq_queue *
2081	cfq_prio_tree_lookup(struct cfq_data cfqd, struct rb_root root,
2082	sector_t sector, struct rb_node **ret_parent,
2083	struct rb_node ***rb_link)
2084	{
2085	struct rb_node *p, parent;
2086	struct cfq_queue *cfqq = NULL;
2087
2088	parent = NULL;
2089	p = &root->rb_node;
2090	while (*p) {
2091	struct rb_node **n;
2092
2093	parent = *p;
2094	cfqq = rb_entry(parent, struct cfq_queue, p_node);
2095
2096	/*
2097	* Sort strictly based on sector. Smallest to the left,
2098	* largest to the right.
2099	*/
2100	if (sector > blk_rq_pos(cfqq->next_rq))
2101	n = &(*p)->rb_right;
2102	else if (sector < blk_rq_pos(cfqq->next_rq))
2103	n = &(*p)->rb_left;
2104	else
2105	break;
2106	p = n;
2107	cfqq = NULL;
2108	}
2109
2110	*ret_parent = parent;
2111	if (rb_link)
2112	*rb_link = p;
2113	return cfqq;
2114	}
2115
2116	static void cfq_prio_tree_add(struct cfq_data cfqd, struct cfq_queue cfqq)
2117	{
2118	struct rb_node *p, parent;
2119	struct cfq_queue *__cfqq;
2120
2121	if (cfqq->p_root) {
2122	rb_erase(&cfqq->p_node, cfqq->p_root);
2123	cfqq->p_root = NULL;
2124	}
2125
2126	if (cfq_class_idle(cfqq))
2127	return;
2128	if (!cfqq->next_rq)
2129	return;
2130
2131	cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2132	__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2133	blk_rq_pos(cfqq->next_rq), &parent, &p);
2134	if (!__cfqq) {
2135	rb_link_node(&cfqq->p_node, parent, p);
2136	rb_insert_color(&cfqq->p_node, cfqq->p_root);
2137	} else
2138	cfqq->p_root = NULL;
2139	}
2140
2141	/*
2142	* Update cfqq's position in the service tree.
2143	*/
2144	static void cfq_resort_rr_list(struct cfq_data cfqd, struct cfq_queue cfqq)
2145	{
2146	/*
2147	* Resorting requires the cfqq to be on the RR list already.
2148	*/
2149	if (cfq_cfqq_on_rr(cfqq)) {
2150	cfq_service_tree_add(cfqd, cfqq, 0);
2151	cfq_prio_tree_add(cfqd, cfqq);
2152	}
2153	}
2154
2155	/*
2156	* add to busy list of queues for service, trying to be fair in ordering
2157	* the pending list according to last request service
2158	*/
2159	static void cfq_add_cfqq_rr(struct cfq_data cfqd, struct cfq_queue cfqq)
2160	{
2161	cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2162	BUG_ON(cfq_cfqq_on_rr(cfqq));
2163	cfq_mark_cfqq_on_rr(cfqq);
2164	cfqd->busy_queues++;
2165	if (cfq_cfqq_sync(cfqq))
2166	cfqd->busy_sync_queues++;
2167
2168	cfq_resort_rr_list(cfqd, cfqq);
2169	}
2170
2171	/*
2172	* Called when the cfqq no longer has requests pending, remove it from
2173	* the service tree.
2174	*/
2175	static void cfq_del_cfqq_rr(struct cfq_data cfqd, struct cfq_queue cfqq)
2176	{
2177	cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2178	BUG_ON(!cfq_cfqq_on_rr(cfqq));
2179	cfq_clear_cfqq_on_rr(cfqq);
2180
2181	if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2182	cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2183	cfqq->service_tree = NULL;
2184	}
2185	if (cfqq->p_root) {
2186	rb_erase(&cfqq->p_node, cfqq->p_root);
2187	cfqq->p_root = NULL;
2188	}
2189
2190	cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2191	BUG_ON(!cfqd->busy_queues);
2192	cfqd->busy_queues--;
2193	if (cfq_cfqq_sync(cfqq))
2194	cfqd->busy_sync_queues--;
2195	}
2196
2197	/*
2198	* rb tree support functions
2199	*/
2200	static void cfq_del_rq_rb(struct request *rq)
2201	{
2202	struct cfq_queue *cfqq = RQ_CFQQ(rq);
2203	const int sync = rq_is_sync(rq);
2204
2205	BUG_ON(!cfqq->queued[sync]);
2206	cfqq->queued[sync]--;
2207
2208	elv_rb_del(&cfqq->sort_list, rq);
2209
2210	if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2211	/*
2212	* Queue will be deleted from service tree when we actually
2213	* expire it later. Right now just remove it from prio tree
2214	* as it is empty.
2215	*/
2216	if (cfqq->p_root) {
2217	rb_erase(&cfqq->p_node, cfqq->p_root);
2218	cfqq->p_root = NULL;
2219	}
2220	}
2221	}
2222
2223	static void cfq_add_rq_rb(struct request *rq)
2224	{
2225	struct cfq_queue *cfqq = RQ_CFQQ(rq);
2226	struct cfq_data *cfqd = cfqq->cfqd;
2227	struct request *prev;
2228
2229	cfqq->queued[rq_is_sync(rq)]++;
2230
2231	elv_rb_add(&cfqq->sort_list, rq);
2232
2233	if (!cfq_cfqq_on_rr(cfqq))
2234	cfq_add_cfqq_rr(cfqd, cfqq);
2235
2236	/*
2237	* check if this request is a better next-serve candidate
2238	*/
2239	prev = cfqq->next_rq;
2240	cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2241
2242	/*
2243	* adjust priority tree position, if ->next_rq changes
2244	*/
2245	if (prev != cfqq->next_rq)
2246	cfq_prio_tree_add(cfqd, cfqq);
2247
2248	BUG_ON(!cfqq->next_rq);
2249	}
2250
2251	static void cfq_reposition_rq_rb(struct cfq_queue cfqq, struct request rq)
2252	{
2253	elv_rb_del(&cfqq->sort_list, rq);
2254	cfqq->queued[rq_is_sync(rq)]--;
2255	cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2256	cfq_add_rq_rb(rq);
2257	cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2258	rq->cmd_flags);
2259	}
2260
2261	static struct request *
2262	cfq_find_rq_fmerge(struct cfq_data cfqd, struct bio bio)
2263	{
2264	struct task_struct *tsk = current;
2265	struct cfq_io_cq *cic;
2266	struct cfq_queue *cfqq;
2267
2268	cic = cfq_cic_lookup(cfqd, tsk->io_context);
2269	if (!cic)
2270	return NULL;
2271
2272	cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2273	if (cfqq) {
2274	sector_t sector = bio->bi_sector + bio_sectors(bio);
2275
2276	return elv_rb_find(&cfqq->sort_list, sector);
2277	}
2278
2279	return NULL;
2280	}
2281
2282	static void cfq_activate_request(struct request_queue q, struct request rq)
2283	{
2284	struct cfq_data *cfqd = q->elevator->elevator_data;
2285
2286	cfqd->rq_in_driver++;
2287	cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2288	cfqd->rq_in_driver);
2289
2290	cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2291	}
2292
2293	static void cfq_deactivate_request(struct request_queue q, struct request rq)
2294	{
2295	struct cfq_data *cfqd = q->elevator->elevator_data;
2296
2297	WARN_ON(!cfqd->rq_in_driver);
2298	cfqd->rq_in_driver--;
2299	cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2300	cfqd->rq_in_driver);
2301	}
2302
2303	static void cfq_remove_request(struct request *rq)
2304	{
2305	struct cfq_queue *cfqq = RQ_CFQQ(rq);
2306
2307	if (cfqq->next_rq == rq)
2308	cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2309
2310	list_del_init(&rq->queuelist);
2311	cfq_del_rq_rb(rq);
2312
2313	cfqq->cfqd->rq_queued--;
2314	cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2315	if (rq->cmd_flags & REQ_PRIO) {
2316	WARN_ON(!cfqq->prio_pending);
2317	cfqq->prio_pending--;
2318	}
2319	}
2320
2321	static int cfq_merge(struct request_queue q, struct request *req,
2322	struct bio *bio)
2323	{
2324	struct cfq_data *cfqd = q->elevator->elevator_data;
2325	struct request *__rq;
2326
2327	__rq = cfq_find_rq_fmerge(cfqd, bio);
2328	if (__rq && elv_rq_merge_ok(__rq, bio)) {
2329	*req = __rq;
2330	return ELEVATOR_FRONT_MERGE;
2331	}
2332
2333	return ELEVATOR_NO_MERGE;
2334	}
2335
2336	static void cfq_merged_request(struct request_queue q, struct request req,
2337	int type)
2338	{
2339	if (type == ELEVATOR_FRONT_MERGE) {
2340	struct cfq_queue *cfqq = RQ_CFQQ(req);
2341
2342	cfq_reposition_rq_rb(cfqq, req);
2343	}
2344	}
2345
2346	static void cfq_bio_merged(struct request_queue q, struct request req,
2347	struct bio *bio)
2348	{
2349	cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
2350	}
2351
2352	static void
2353	cfq_merged_requests(struct request_queue q, struct request rq,
2354	struct request *next)
2355	{
2356	struct cfq_queue *cfqq = RQ_CFQQ(rq);
2357	struct cfq_data *cfqd = q->elevator->elevator_data;
2358
2359	/*
2360	* reposition in fifo if next is older than rq
2361	*/
2362	if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2363	time_before(rq_fifo_time(next), rq_fifo_time(rq)) &&
2364	cfqq == RQ_CFQQ(next)) {
2365	list_move(&rq->queuelist, &next->queuelist);
2366	rq_set_fifo_time(rq, rq_fifo_time(next));
2367	}
2368
2369	if (cfqq->next_rq == next)
2370	cfqq->next_rq = rq;
2371	cfq_remove_request(next);
2372	cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
2373
2374	cfqq = RQ_CFQQ(next);
2375	/*
2376	* all requests of this queue are merged to other queues, delete it
2377	* from the service tree. If it's the active_queue,
2378	* cfq_dispatch_requests() will choose to expire it or do idle
2379	*/
2380	if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2381	cfqq != cfqd->active_queue)
2382	cfq_del_cfqq_rr(cfqd, cfqq);
2383	}
2384
2385	static int cfq_allow_merge(struct request_queue q, struct request rq,
2386	struct bio *bio)
2387	{
2388	struct cfq_data *cfqd = q->elevator->elevator_data;
2389	struct cfq_io_cq *cic;
2390	struct cfq_queue *cfqq;
2391
2392	/*
2393	* Disallow merge of a sync bio into an async request.
2394	*/
2395	if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2396	return false;
2397
2398	/*
2399	* Lookup the cfqq that this bio will be queued with and allow
2400	* merge only if rq is queued there.
2401	*/
2402	cic = cfq_cic_lookup(cfqd, current->io_context);
2403	if (!cic)
2404	return false;
2405
2406	cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2407	return cfqq == RQ_CFQQ(rq);
2408	}
2409
2410	static inline void cfq_del_timer(struct cfq_data cfqd, struct cfq_queue cfqq)
2411	{
2412	del_timer(&cfqd->idle_slice_timer);
2413	cfqg_stats_update_idle_time(cfqq->cfqg);
2414	}
2415
2416	static void __cfq_set_active_queue(struct cfq_data *cfqd,
2417	struct cfq_queue *cfqq)
2418	{
2419	if (cfqq) {
2420	cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2421	cfqd->serving_wl_class, cfqd->serving_wl_type);
2422	cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2423	cfqq->slice_start = 0;
2424	cfqq->dispatch_start = jiffies;
2425	cfqq->allocated_slice = 0;
2426	cfqq->slice_end = 0;
2427	cfqq->slice_dispatch = 0;
2428	cfqq->nr_sectors = 0;
2429
2430	cfq_clear_cfqq_wait_request(cfqq);
2431	cfq_clear_cfqq_must_dispatch(cfqq);
2432	cfq_clear_cfqq_must_alloc_slice(cfqq);
2433	cfq_clear_cfqq_fifo_expire(cfqq);
2434	cfq_mark_cfqq_slice_new(cfqq);
2435
2436	cfq_del_timer(cfqd, cfqq);
2437	}
2438
2439	cfqd->active_queue = cfqq;
2440	}
2441
2442	/*
2443	* current cfqq expired its slice (or was too idle), select new one
2444	*/
2445	static void
2446	__cfq_slice_expired(struct cfq_data cfqd, struct cfq_queue cfqq,
2447	bool timed_out)
2448	{
2449	cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2450
2451	if (cfq_cfqq_wait_request(cfqq))
2452	cfq_del_timer(cfqd, cfqq);
2453
2454	cfq_clear_cfqq_wait_request(cfqq);
2455	cfq_clear_cfqq_wait_busy(cfqq);
2456
2457	/*
2458	* If this cfqq is shared between multiple processes, check to
2459	* make sure that those processes are still issuing I/Os within
2460	* the mean seek distance. If not, it may be time to break the
2461	* queues apart again.
2462	*/
2463	if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2464	cfq_mark_cfqq_split_coop(cfqq);
2465
2466	/*
2467	* store what was left of this slice, if the queue idled/timed out
2468	*/
2469	if (timed_out) {
2470	if (cfq_cfqq_slice_new(cfqq))
2471	cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2472	else
2473	cfqq->slice_resid = cfqq->slice_end - jiffies;
2474	cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2475	}
2476
2477	cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2478
2479	if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2480	cfq_del_cfqq_rr(cfqd, cfqq);
2481
2482	cfq_resort_rr_list(cfqd, cfqq);
2483
2484	if (cfqq == cfqd->active_queue)
2485	cfqd->active_queue = NULL;
2486
2487	if (cfqd->active_cic) {
2488	put_io_context(cfqd->active_cic->icq.ioc);
2489	cfqd->active_cic = NULL;
2490	}
2491	}
2492
2493	static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2494	{
2495	struct cfq_queue *cfqq = cfqd->active_queue;
2496
2497	if (cfqq)
2498	__cfq_slice_expired(cfqd, cfqq, timed_out);
2499	}
2500
2501	/*
2502	* Get next queue for service. Unless we have a queue preemption,
2503	* we'll simply select the first cfqq in the service tree.
2504	*/
2505	static struct cfq_queue cfq_get_next_queue(struct cfq_data cfqd)
2506	{
2507	struct cfq_rb_root *st = st_for(cfqd->serving_group,
2508	cfqd->serving_wl_class, cfqd->serving_wl_type);
2509
2510	if (!cfqd->rq_queued)
2511	return NULL;
2512
2513	/* There is nothing to dispatch */
2514	if (!st)
2515	return NULL;
2516	if (RB_EMPTY_ROOT(&st->rb))
2517	return NULL;
2518	return cfq_rb_first(st);
2519	}
2520
2521	static struct cfq_queue cfq_get_next_queue_forced(struct cfq_data cfqd)
2522	{
2523	struct cfq_group *cfqg;
2524	struct cfq_queue *cfqq;
2525	int i, j;
2526	struct cfq_rb_root *st;
2527
2528	if (!cfqd->rq_queued)
2529	return NULL;
2530
2531	cfqg = cfq_get_next_cfqg(cfqd);
2532	if (!cfqg)
2533	return NULL;
2534
2535	for_each_cfqg_st(cfqg, i, j, st)
2536	if ((cfqq = cfq_rb_first(st)) != NULL)
2537	return cfqq;
2538	return NULL;
2539	}
2540
2541	/*
2542	* Get and set a new active queue for service.
2543	*/
2544	static struct cfq_queue cfq_set_active_queue(struct cfq_data cfqd,
2545	struct cfq_queue *cfqq)
2546	{
2547	if (!cfqq)
2548	cfqq = cfq_get_next_queue(cfqd);
2549
2550	__cfq_set_active_queue(cfqd, cfqq);
2551	return cfqq;
2552	}
2553
2554	static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2555	struct request *rq)
2556	{
2557	if (blk_rq_pos(rq) >= cfqd->last_position)
2558	return blk_rq_pos(rq) - cfqd->last_position;
2559	else
2560	return cfqd->last_position - blk_rq_pos(rq);
2561	}
2562
2563	static inline int cfq_rq_close(struct cfq_data cfqd, struct cfq_queue cfqq,
2564	struct request *rq)
2565	{
2566	return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2567	}
2568
2569	static struct cfq_queue cfqq_close(struct cfq_data cfqd,
2570	struct cfq_queue *cur_cfqq)
2571	{
2572	struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2573	struct rb_node parent, node;
2574	struct cfq_queue *__cfqq;
2575	sector_t sector = cfqd->last_position;
2576
2577	if (RB_EMPTY_ROOT(root))
2578	return NULL;
2579
2580	/*
2581	* First, if we find a request starting at the end of the last
2582	* request, choose it.
2583	*/
2584	__cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2585	if (__cfqq)
2586	return __cfqq;
2587
2588	/*
2589	* If the exact sector wasn't found, the parent of the NULL leaf
2590	* will contain the closest sector.
2591	*/
2592	__cfqq = rb_entry(parent, struct cfq_queue, p_node);
2593	if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2594	return __cfqq;
2595
2596	if (blk_rq_pos(__cfqq->next_rq) < sector)
2597	node = rb_next(&__cfqq->p_node);
2598	else
2599	node = rb_prev(&__cfqq->p_node);
2600	if (!node)
2601	return NULL;
2602
2603	__cfqq = rb_entry(node, struct cfq_queue, p_node);
2604	if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2605	return __cfqq;
2606
2607	return NULL;
2608	}
2609
2610	/*
2611	* cfqd - obvious
2612	* cur_cfqq - passed in so that we don't decide that the current queue is
2613	* closely cooperating with itself.
2614	*
2615	* So, basically we're assuming that that cur_cfqq has dispatched at least
2616	* one request, and that cfqd->last_position reflects a position on the disk
2617	* associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2618	* assumption.
2619	*/
2620	static struct cfq_queue cfq_close_cooperator(struct cfq_data cfqd,
2621	struct cfq_queue *cur_cfqq)
2622	{
2623	struct cfq_queue *cfqq;
2624
2625	if (cfq_class_idle(cur_cfqq))
2626	return NULL;
2627	if (!cfq_cfqq_sync(cur_cfqq))
2628	return NULL;
2629	if (CFQQ_SEEKY(cur_cfqq))
2630	return NULL;
2631
2632	/*
2633	* Don't search priority tree if it's the only queue in the group.
2634	*/
2635	if (cur_cfqq->cfqg->nr_cfqq == 1)
2636	return NULL;
2637
2638	/*
2639	* We should notice if some of the queues are cooperating, eg
2640	* working closely on the same area of the disk. In that case,
2641	* we can group them together and don't waste time idling.
2642	*/
2643	cfqq = cfqq_close(cfqd, cur_cfqq);
2644	if (!cfqq)
2645	return NULL;
2646
2647	/* If new queue belongs to different cfq_group, don't choose it */
2648	if (cur_cfqq->cfqg != cfqq->cfqg)
2649	return NULL;
2650
2651	/*
2652	* It only makes sense to merge sync queues.
2653	*/
2654	if (!cfq_cfqq_sync(cfqq))
2655	return NULL;
2656	if (CFQQ_SEEKY(cfqq))
2657	return NULL;
2658
2659	/*
2660	* Do not merge queues of different priority classes
2661	*/
2662	if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2663	return NULL;
2664
2665	return cfqq;
2666	}
2667
2668	/*
2669	* Determine whether we should enforce idle window for this queue.
2670	*/
2671
2672	static bool cfq_should_idle(struct cfq_data cfqd, struct cfq_queue cfqq)
2673	{
2674	enum wl_class_t wl_class = cfqq_class(cfqq);
2675	struct cfq_rb_root *st = cfqq->service_tree;
2676
2677	BUG_ON(!st);
2678	BUG_ON(!st->count);
2679
2680	if (!cfqd->cfq_slice_idle)
2681	return false;
2682
2683	/* We never do for idle class queues. */
2684	if (wl_class == IDLE_WORKLOAD)
2685	return false;
2686
2687	/* We do for queues that were marked with idle window flag. */
2688	if (cfq_cfqq_idle_window(cfqq) &&
2689	!(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2690	return true;
2691
2692	/*
2693	* Otherwise, we do only if they are the last ones
2694	* in their service tree.
2695	*/
2696	if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2697	!cfq_io_thinktime_big(cfqd, &st->ttime, false))
2698	return true;
2699	cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2700	return false;
2701	}
2702
2703	static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2704	{
2705	struct cfq_queue *cfqq = cfqd->active_queue;
2706	struct cfq_io_cq *cic;
2707	unsigned long sl, group_idle = 0;
2708
2709	/*
2710	* SSD device without seek penalty, disable idling. But only do so
2711	* for devices that support queuing, otherwise we still have a problem
2712	* with sync vs async workloads.
2713	*/
2714	if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2715	return;
2716
2717	WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2718	WARN_ON(cfq_cfqq_slice_new(cfqq));
2719
2720	/*
2721	* idle is disabled, either manually or by past process history
2722	*/
2723	if (!cfq_should_idle(cfqd, cfqq)) {
2724	/* no queue idling. Check for group idling */
2725	if (cfqd->cfq_group_idle)
2726	group_idle = cfqd->cfq_group_idle;
2727	else
2728	return;
2729	}
2730
2731	/*
2732	* still active requests from this queue, don't idle
2733	*/
2734	if (cfqq->dispatched)
2735	return;
2736
2737	/*
2738	* task has exited, don't wait
2739	*/
2740	cic = cfqd->active_cic;
2741	if (!cic \|\| !atomic_read(&cic->icq.ioc->active_ref))
2742	return;
2743
2744	/*
2745	* If our average think time is larger than the remaining time
2746	* slice, then don't idle. This avoids overrunning the allotted
2747	* time slice.
2748	*/
2749	if (sample_valid(cic->ttime.ttime_samples) &&
2750	(cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2751	cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2752	cic->ttime.ttime_mean);
2753	return;
2754	}
2755
2756	/* There are other queues in the group, don't do group idle */
2757	if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2758	return;
2759
2760	cfq_mark_cfqq_wait_request(cfqq);
2761
2762	if (group_idle)
2763	sl = cfqd->cfq_group_idle;
2764	else
2765	sl = cfqd->cfq_slice_idle;
2766
2767	mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2768	cfqg_stats_set_start_idle_time(cfqq->cfqg);
2769	cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2770	group_idle ? 1 : 0);
2771	}
2772
2773	/*
2774	* Move request from internal lists to the request queue dispatch list.
2775	*/
2776	static void cfq_dispatch_insert(struct request_queue q, struct request rq)
2777	{
2778	struct cfq_data *cfqd = q->elevator->elevator_data;
2779	struct cfq_queue *cfqq = RQ_CFQQ(rq);
2780
2781	cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2782
2783	cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2784	cfq_remove_request(rq);
2785	cfqq->dispatched++;
2786	(RQ_CFQG(rq))->dispatched++;
2787	elv_dispatch_sort(q, rq);
2788
2789	cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2790	cfqq->nr_sectors += blk_rq_sectors(rq);
2791	cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2792	}
2793
2794	/*
2795	* return expired entry, or NULL to just start from scratch in rbtree
2796	*/
2797	static struct request cfq_check_fifo(struct cfq_queue cfqq)
2798	{
2799	struct request *rq = NULL;
2800
2801	if (cfq_cfqq_fifo_expire(cfqq))
2802	return NULL;
2803
2804	cfq_mark_cfqq_fifo_expire(cfqq);
2805
2806	if (list_empty(&cfqq->fifo))
2807	return NULL;
2808
2809	rq = rq_entry_fifo(cfqq->fifo.next);
2810	if (time_before(jiffies, rq_fifo_time(rq)))
2811	rq = NULL;
2812
2813	cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2814	return rq;
2815	}
2816
2817	static inline int
2818	cfq_prio_to_maxrq(struct cfq_data cfqd, struct cfq_queue cfqq)
2819	{
2820	const int base_rq = cfqd->cfq_slice_async_rq;
2821
2822	WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2823
2824	return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2825	}
2826
2827	/*
2828	* Must be called with the queue_lock held.
2829	*/
2830	static int cfqq_process_refs(struct cfq_queue *cfqq)
2831	{
2832	int process_refs, io_refs;
2833
2834	io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2835	process_refs = cfqq->ref - io_refs;
2836	BUG_ON(process_refs < 0);
2837	return process_refs;
2838	}
2839
2840	static void cfq_setup_merge(struct cfq_queue cfqq, struct cfq_queue new_cfqq)
2841	{
2842	int process_refs, new_process_refs;
2843	struct cfq_queue *__cfqq;
2844
2845	/*
2846	* If there are no process references on the new_cfqq, then it is
2847	* unsafe to follow the ->new_cfqq chain as other cfqq's in the
2848	* chain may have dropped their last reference (not just their
2849	* last process reference).
2850	*/
2851	if (!cfqq_process_refs(new_cfqq))
2852	return;
2853
2854	/* Avoid a circular list and skip interim queue merges */
2855	while ((__cfqq = new_cfqq->new_cfqq)) {
2856	if (__cfqq == cfqq)
2857	return;
2858	new_cfqq = __cfqq;
2859	}
2860
2861	process_refs = cfqq_process_refs(cfqq);
2862	new_process_refs = cfqq_process_refs(new_cfqq);
2863	/*
2864	* If the process for the cfqq has gone away, there is no
2865	* sense in merging the queues.
2866	*/
2867	if (process_refs == 0 \|\| new_process_refs == 0)
2868	return;
2869
2870	/*
2871	* Merge in the direction of the lesser amount of work.
2872	*/
2873	if (new_process_refs >= process_refs) {
2874	cfqq->new_cfqq = new_cfqq;
2875	new_cfqq->ref += process_refs;
2876	} else {
2877	new_cfqq->new_cfqq = cfqq;
2878	cfqq->ref += new_process_refs;
2879	}
2880	}
2881
2882	static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
2883	struct cfq_group *cfqg, enum wl_class_t wl_class)
2884	{
2885	struct cfq_queue *queue;
2886	int i;
2887	bool key_valid = false;
2888	unsigned long lowest_key = 0;
2889	enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2890
2891	for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2892	/* select the one with lowest rb_key */
2893	queue = cfq_rb_first(st_for(cfqg, wl_class, i));
2894	if (queue &&
2895	(!key_valid \|\| time_before(queue->rb_key, lowest_key))) {
2896	lowest_key = queue->rb_key;
2897	cur_best = i;
2898	key_valid = true;
2899	}
2900	}
2901
2902	return cur_best;
2903	}
2904
2905	static void
2906	choose_wl_class_and_type(struct cfq_data cfqd, struct cfq_group cfqg)
2907	{
2908	unsigned slice;
2909	unsigned count;
2910	struct cfq_rb_root *st;
2911	unsigned group_slice;
2912	enum wl_class_t original_class = cfqd->serving_wl_class;
2913
2914	/* Choose next priority. RT > BE > IDLE */
2915	if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2916	cfqd->serving_wl_class = RT_WORKLOAD;
2917	else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2918	cfqd->serving_wl_class = BE_WORKLOAD;
2919	else {
2920	cfqd->serving_wl_class = IDLE_WORKLOAD;
2921	cfqd->workload_expires = jiffies + 1;
2922	return;
2923	}
2924
2925	if (original_class != cfqd->serving_wl_class)
2926	goto new_workload;
2927
2928	/*
2929	* For RT and BE, we have to choose also the type
2930	* (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2931	* expiration time
2932	*/
2933	st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
2934	count = st->count;
2935
2936	/*
2937	* check workload expiration, and that we still have other queues ready
2938	*/
2939	if (count && !time_after(jiffies, cfqd->workload_expires))
2940	return;
2941
2942	new_workload:
2943	/* otherwise select new workload type */
2944	cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
2945	cfqd->serving_wl_class);
2946	st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
2947	count = st->count;
2948
2949	/*
2950	* the workload slice is computed as a fraction of target latency
2951	* proportional to the number of queues in that workload, over
2952	* all the queues in the same priority class
2953	*/
2954	group_slice = cfq_group_slice(cfqd, cfqg);
2955
2956	slice = group_slice * count /
2957	max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
2958	cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
2959	cfqg));
2960
2961	if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
2962	unsigned int tmp;
2963
2964	/*
2965	* Async queues are currently system wide. Just taking
2966	* proportion of queues with-in same group will lead to higher
2967	* async ratio system wide as generally root group is going
2968	* to have higher weight. A more accurate thing would be to
2969	* calculate system wide asnc/sync ratio.
2970	*/
2971	tmp = cfqd->cfq_target_latency *
2972	cfqg_busy_async_queues(cfqd, cfqg);
2973	tmp = tmp/cfqd->busy_queues;
2974	slice = min_t(unsigned, slice, tmp);
2975
2976	/* async workload slice is scaled down according to
2977	* the sync/async slice ratio. */
2978	slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2979	} else
2980	/* sync workload slice is at least 2 * cfq_slice_idle */
2981	slice = max(slice, 2 * cfqd->cfq_slice_idle);
2982
2983	slice = max_t(unsigned, slice, CFQ_MIN_TT);
2984	cfq_log(cfqd, "workload slice:%d", slice);
2985	cfqd->workload_expires = jiffies + slice;
2986	}
2987
2988	static struct cfq_group cfq_get_next_cfqg(struct cfq_data cfqd)
2989	{
2990	struct cfq_rb_root *st = &cfqd->grp_service_tree;
2991	struct cfq_group *cfqg;
2992
2993	if (RB_EMPTY_ROOT(&st->rb))
2994	return NULL;
2995	cfqg = cfq_rb_first_group(st);
2996	update_min_vdisktime(st);
2997	return cfqg;
2998	}
2999
3000	static void cfq_choose_cfqg(struct cfq_data *cfqd)
3001	{
3002	struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3003
3004	cfqd->serving_group = cfqg;
3005
3006	/* Restore the workload type data */
3007	if (cfqg->saved_wl_slice) {
3008	cfqd->workload_expires = jiffies + cfqg->saved_wl_slice;
3009	cfqd->serving_wl_type = cfqg->saved_wl_type;
3010	cfqd->serving_wl_class = cfqg->saved_wl_class;
3011	} else
3012	cfqd->workload_expires = jiffies - 1;
3013
3014	choose_wl_class_and_type(cfqd, cfqg);
3015	}
3016
3017	/*
3018	* Select a queue for service. If we have a current active queue,
3019	* check whether to continue servicing it, or retrieve and set a new one.
3020	*/
3021	static struct cfq_queue cfq_select_queue(struct cfq_data cfqd)
3022	{
3023	struct cfq_queue cfqq, new_cfqq = NULL;
3024
3025	cfqq = cfqd->active_queue;
3026	if (!cfqq)
3027	goto new_queue;
3028
3029	if (!cfqd->rq_queued)
3030	return NULL;
3031
3032	/*
3033	* We were waiting for group to get backlogged. Expire the queue
3034	*/
3035	if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3036	goto expire;
3037
3038	/*
3039	* The active queue has run out of time, expire it and select new.
3040	*/
3041	if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3042	/*
3043	* If slice had not expired at the completion of last request
3044	* we might not have turned on wait_busy flag. Don't expire
3045	* the queue yet. Allow the group to get backlogged.
3046	*
3047	* The very fact that we have used the slice, that means we
3048	* have been idling all along on this queue and it should be
3049	* ok to wait for this request to complete.
3050	*/
3051	if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3052	&& cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3053	cfqq = NULL;
3054	goto keep_queue;
3055	} else
3056	goto check_group_idle;
3057	}
3058
3059	/*
3060	* The active queue has requests and isn't expired, allow it to
3061	* dispatch.
3062	*/
3063	if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3064	goto keep_queue;
3065
3066	/*
3067	* If another queue has a request waiting within our mean seek
3068	* distance, let it run. The expire code will check for close
3069	* cooperators and put the close queue at the front of the service
3070	* tree. If possible, merge the expiring queue with the new cfqq.
3071	*/
3072	new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3073	if (new_cfqq) {
3074	if (!cfqq->new_cfqq)
3075	cfq_setup_merge(cfqq, new_cfqq);
3076	goto expire;
3077	}
3078
3079	/*
3080	* No requests pending. If the active queue still has requests in
3081	* flight or is idling for a new request, allow either of these
3082	* conditions to happen (or time out) before selecting a new queue.
3083	*/
3084	if (timer_pending(&cfqd->idle_slice_timer)) {
3085	cfqq = NULL;
3086	goto keep_queue;
3087	}
3088
3089	/*
3090	* This is a deep seek queue, but the device is much faster than
3091	* the queue can deliver, don't idle
3092	**/
3093	if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3094	(cfq_cfqq_slice_new(cfqq) \|\|
3095	(cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
3096	cfq_clear_cfqq_deep(cfqq);
3097	cfq_clear_cfqq_idle_window(cfqq);
3098	}
3099
3100	if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3101	cfqq = NULL;
3102	goto keep_queue;
3103	}
3104
3105	/*
3106	* If group idle is enabled and there are requests dispatched from
3107	* this group, wait for requests to complete.
3108	*/
3109	check_group_idle:
3110	if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3111	cfqq->cfqg->dispatched &&
3112	!cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3113	cfqq = NULL;
3114	goto keep_queue;
3115	}
3116
3117	expire:
3118	cfq_slice_expired(cfqd, 0);
3119	new_queue:
3120	/*
3121	* Current queue expired. Check if we have to switch to a new
3122	* service tree
3123	*/
3124	if (!new_cfqq)
3125	cfq_choose_cfqg(cfqd);
3126
3127	cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3128	keep_queue:
3129	return cfqq;
3130	}
3131
3132	static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3133	{
3134	int dispatched = 0;
3135
3136	while (cfqq->next_rq) {
3137	cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3138	dispatched++;
3139	}
3140
3141	BUG_ON(!list_empty(&cfqq->fifo));
3142
3143	/* By default cfqq is not expired if it is empty. Do it explicitly */
3144	__cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3145	return dispatched;
3146	}
3147
3148	/*
3149	* Drain our current requests. Used for barriers and when switching
3150	* io schedulers on-the-fly.
3151	*/
3152	static int cfq_forced_dispatch(struct cfq_data *cfqd)
3153	{
3154	struct cfq_queue *cfqq;
3155	int dispatched = 0;
3156
3157	/* Expire the timeslice of the current active queue first */
3158	cfq_slice_expired(cfqd, 0);
3159	while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3160	__cfq_set_active_queue(cfqd, cfqq);
3161	dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3162	}
3163
3164	BUG_ON(cfqd->busy_queues);
3165
3166	cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3167	return dispatched;
3168	}
3169
3170	static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3171	struct cfq_queue *cfqq)
3172	{
3173	/* the queue hasn't finished any request, can't estimate */
3174	if (cfq_cfqq_slice_new(cfqq))
3175	return true;
3176	if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
3177	cfqq->slice_end))
3178	return true;
3179
3180	return false;
3181	}
3182
3183	static bool cfq_may_dispatch(struct cfq_data cfqd, struct cfq_queue cfqq)
3184	{
3185	unsigned int max_dispatch;
3186
3187	/*
3188	* Drain async requests before we start sync IO
3189	*/
3190	if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3191	return false;
3192
3193	/*
3194	* If this is an async queue and we have sync IO in flight, let it wait
3195	*/
3196	if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3197	return false;
3198
3199	max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3200	if (cfq_class_idle(cfqq))
3201	max_dispatch = 1;
3202
3203	/*
3204	* Does this cfqq already have too much IO in flight?
3205	*/
3206	if (cfqq->dispatched >= max_dispatch) {
3207	bool promote_sync = false;
3208	/*
3209	* idle queue must always only have a single IO in flight
3210	*/
3211	if (cfq_class_idle(cfqq))
3212	return false;
3213
3214	/*
3215	* If there is only one sync queue
3216	* we can ignore async queue here and give the sync
3217	* queue no dispatch limit. The reason is a sync queue can
3218	* preempt async queue, limiting the sync queue doesn't make
3219	* sense. This is useful for aiostress test.
3220	*/
3221	if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3222	promote_sync = true;
3223
3224	/*
3225	* We have other queues, don't allow more IO from this one
3226	*/
3227	if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3228	!promote_sync)
3229	return false;
3230
3231	/*
3232	* Sole queue user, no limit
3233	*/
3234	if (cfqd->busy_queues == 1 \|\| promote_sync)
3235	max_dispatch = -1;
3236	else
3237	/*
3238	* Normally we start throttling cfqq when cfq_quantum/2
3239	* requests have been dispatched. But we can drive
3240	* deeper queue depths at the beginning of slice
3241	* subjected to upper limit of cfq_quantum.
3242	* */
3243	max_dispatch = cfqd->cfq_quantum;
3244	}
3245
3246	/*
3247	* Async queues must wait a bit before being allowed dispatch.
3248	* We also ramp up the dispatch depth gradually for async IO,
3249	* based on the last sync IO we serviced
3250	*/
3251	if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3252	unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
3253	unsigned int depth;
3254
3255	depth = last_sync / cfqd->cfq_slice[1];
3256	if (!depth && !cfqq->dispatched)
3257	depth = 1;
3258	if (depth < max_dispatch)
3259	max_dispatch = depth;
3260	}
3261
3262	/*
3263	* If we're below the current max, allow a dispatch
3264	*/
3265	return cfqq->dispatched < max_dispatch;
3266	}
3267
3268	/*
3269	* Dispatch a request from cfqq, moving them to the request queue
3270	* dispatch list.
3271	*/
3272	static bool cfq_dispatch_request(struct cfq_data cfqd, struct cfq_queue cfqq)
3273	{
3274	struct request *rq;
3275
3276	BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3277
3278	if (!cfq_may_dispatch(cfqd, cfqq))
3279	return false;
3280
3281	/*
3282	* follow expired path, else get first next available
3283	*/
3284	rq = cfq_check_fifo(cfqq);
3285	if (!rq)
3286	rq = cfqq->next_rq;
3287
3288	/*
3289	* insert request into driver dispatch list
3290	*/
3291	cfq_dispatch_insert(cfqd->queue, rq);
3292
3293	if (!cfqd->active_cic) {
3294	struct cfq_io_cq *cic = RQ_CIC(rq);
3295
3296	atomic_long_inc(&cic->icq.ioc->refcount);
3297	cfqd->active_cic = cic;
3298	}
3299
3300	return true;
3301	}
3302
3303	/*
3304	* Find the cfqq that we need to service and move a request from that to the
3305	* dispatch list
3306	*/
3307	static int cfq_dispatch_requests(struct request_queue *q, int force)
3308	{
3309	struct cfq_data *cfqd = q->elevator->elevator_data;
3310	struct cfq_queue *cfqq;
3311
3312	if (!cfqd->busy_queues)
3313	return 0;
3314
3315	if (unlikely(force))
3316	return cfq_forced_dispatch(cfqd);
3317
3318	cfqq = cfq_select_queue(cfqd);
3319	if (!cfqq)
3320	return 0;
3321
3322	/*
3323	* Dispatch a request from this cfqq, if it is allowed
3324	*/
3325	if (!cfq_dispatch_request(cfqd, cfqq))
3326	return 0;
3327
3328	cfqq->slice_dispatch++;
3329	cfq_clear_cfqq_must_dispatch(cfqq);
3330
3331	/*
3332	* expire an async queue immediately if it has used up its slice. idle
3333	* queue always expire after 1 dispatch round.
3334	*/
3335	if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3336	cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) \|\|
3337	cfq_class_idle(cfqq))) {
3338	cfqq->slice_end = jiffies + 1;
3339	cfq_slice_expired(cfqd, 0);
3340	}
3341
3342	cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3343	return 1;
3344	}
3345
3346	/*
3347	* task holds one reference to the queue, dropped when task exits. each rq
3348	* in-flight on this queue also holds a reference, dropped when rq is freed.
3349	*
3350	* Each cfq queue took a reference on the parent group. Drop it now.
3351	* queue lock must be held here.
3352	*/
3353	static void cfq_put_queue(struct cfq_queue *cfqq)
3354	{
3355	struct cfq_data *cfqd = cfqq->cfqd;
3356	struct cfq_group *cfqg;
3357
3358	BUG_ON(cfqq->ref <= 0);
3359
3360	cfqq->ref--;
3361	if (cfqq->ref)
3362	return;
3363
3364	cfq_log_cfqq(cfqd, cfqq, "put_queue");
3365	BUG_ON(rb_first(&cfqq->sort_list));
3366	BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3367	cfqg = cfqq->cfqg;
3368
3369	if (unlikely(cfqd->active_queue == cfqq)) {
3370	__cfq_slice_expired(cfqd, cfqq, 0);
3371	cfq_schedule_dispatch(cfqd);
3372	}
3373
3374	BUG_ON(cfq_cfqq_on_rr(cfqq));
3375	kmem_cache_free(cfq_pool, cfqq);
3376	cfqg_put(cfqg);
3377	}
3378
3379	static void cfq_put_cooperator(struct cfq_queue *cfqq)
3380	{
3381	struct cfq_queue __cfqq, next;
3382
3383	/*
3384	* If this queue was scheduled to merge with another queue, be
3385	* sure to drop the reference taken on that queue (and others in
3386	* the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
3387	*/
3388	__cfqq = cfqq->new_cfqq;
3389	while (__cfqq) {
3390	if (__cfqq == cfqq) {
3391	WARN(1, "cfqq->new_cfqq loop detected\n");
3392	break;
3393	}
3394	next = __cfqq->new_cfqq;
3395	cfq_put_queue(__cfqq);
3396	__cfqq = next;
3397	}
3398	}
3399
3400	static void cfq_exit_cfqq(struct cfq_data cfqd, struct cfq_queue cfqq)
3401	{
3402	if (unlikely(cfqq == cfqd->active_queue)) {
3403	__cfq_slice_expired(cfqd, cfqq, 0);
3404	cfq_schedule_dispatch(cfqd);
3405	}
3406
3407	cfq_put_cooperator(cfqq);
3408
3409	cfq_put_queue(cfqq);
3410	}
3411
3412	static void cfq_init_icq(struct io_cq *icq)
3413	{
3414	struct cfq_io_cq *cic = icq_to_cic(icq);
3415
3416	cic->ttime.last_end_request = jiffies;
3417	}
3418
3419	static void cfq_exit_icq(struct io_cq *icq)
3420	{
3421	struct cfq_io_cq *cic = icq_to_cic(icq);
3422	struct cfq_data *cfqd = cic_to_cfqd(cic);
3423
3424	if (cic->cfqq[BLK_RW_ASYNC]) {
3425	cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
3426	cic->cfqq[BLK_RW_ASYNC] = NULL;
3427	}
3428
3429	if (cic->cfqq[BLK_RW_SYNC]) {
3430	cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
3431	cic->cfqq[BLK_RW_SYNC] = NULL;
3432	}
3433	}
3434
3435	static void cfq_init_prio_data(struct cfq_queue cfqq, struct cfq_io_cq cic)
3436	{
3437	struct task_struct *tsk = current;
3438	int ioprio_class;
3439
3440	if (!cfq_cfqq_prio_changed(cfqq))
3441	return;
3442
3443	ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3444	switch (ioprio_class) {
3445	default:
3446	printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3447	case IOPRIO_CLASS_NONE:
3448	/*
3449	* no prio set, inherit CPU scheduling settings
3450	*/
3451	cfqq->ioprio = task_nice_ioprio(tsk);
3452	cfqq->ioprio_class = task_nice_ioclass(tsk);
3453	break;
3454	case IOPRIO_CLASS_RT:
3455	cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3456	cfqq->ioprio_class = IOPRIO_CLASS_RT;
3457	break;
3458	case IOPRIO_CLASS_BE:
3459	cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3460	cfqq->ioprio_class = IOPRIO_CLASS_BE;
3461	break;
3462	case IOPRIO_CLASS_IDLE:
3463	cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3464	cfqq->ioprio = 7;
3465	cfq_clear_cfqq_idle_window(cfqq);
3466	break;
3467	}
3468
3469	/*
3470	* keep track of original prio settings in case we have to temporarily
3471	* elevate the priority of this queue
3472	*/
3473	cfqq->org_ioprio = cfqq->ioprio;
3474	cfq_clear_cfqq_prio_changed(cfqq);
3475	}
3476
3477	static void check_ioprio_changed(struct cfq_io_cq cic, struct bio bio)
3478	{
3479	int ioprio = cic->icq.ioc->ioprio;
3480	struct cfq_data *cfqd = cic_to_cfqd(cic);
3481	struct cfq_queue *cfqq;
3482
3483	/*
3484	* Check whether ioprio has changed. The condition may trigger
3485	* spuriously on a newly created cic but there's no harm.
3486	*/
3487	if (unlikely(!cfqd) \|\| likely(cic->ioprio == ioprio))
3488	return;
3489
3490	cfqq = cic->cfqq[BLK_RW_ASYNC];
3491	if (cfqq) {
3492	struct cfq_queue *new_cfqq;
3493	new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
3494	GFP_ATOMIC);
3495	if (new_cfqq) {
3496	cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
3497	cfq_put_queue(cfqq);
3498	}
3499	}
3500
3501	cfqq = cic->cfqq[BLK_RW_SYNC];
3502	if (cfqq)
3503	cfq_mark_cfqq_prio_changed(cfqq);
3504
3505	cic->ioprio = ioprio;
3506	}
3507
3508	static void cfq_init_cfqq(struct cfq_data cfqd, struct cfq_queue cfqq,
3509	pid_t pid, bool is_sync)
3510	{
3511	RB_CLEAR_NODE(&cfqq->rb_node);
3512	RB_CLEAR_NODE(&cfqq->p_node);
3513	INIT_LIST_HEAD(&cfqq->fifo);
3514
3515	cfqq->ref = 0;
3516	cfqq->cfqd = cfqd;
3517
3518	cfq_mark_cfqq_prio_changed(cfqq);
3519
3520	if (is_sync) {
3521	if (!cfq_class_idle(cfqq))
3522	cfq_mark_cfqq_idle_window(cfqq);
3523	cfq_mark_cfqq_sync(cfqq);
3524	}
3525	cfqq->pid = pid;
3526	}
3527
3528	#ifdef CONFIG_CFQ_GROUP_IOSCHED
3529	static void check_blkcg_changed(struct cfq_io_cq cic, struct bio bio)
3530	{
3531	struct cfq_data *cfqd = cic_to_cfqd(cic);
3532	struct cfq_queue *sync_cfqq;
3533	uint64_t id;
3534
3535	rcu_read_lock();
3536	id = bio_blkcg(bio)->id;
3537	rcu_read_unlock();
3538
3539	/*
3540	* Check whether blkcg has changed. The condition may trigger
3541	* spuriously on a newly created cic but there's no harm.
3542	*/
3543	if (unlikely(!cfqd) \|\| likely(cic->blkcg_id == id))
3544	return;
3545
3546	sync_cfqq = cic_to_cfqq(cic, 1);
3547	if (sync_cfqq) {
3548	/*
3549	* Drop reference to sync queue. A new sync queue will be
3550	* assigned in new group upon arrival of a fresh request.
3551	*/
3552	cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3553	cic_set_cfqq(cic, NULL, 1);
3554	cfq_put_queue(sync_cfqq);
3555	}
3556
3557	cic->blkcg_id = id;
3558	}
3559	#else
3560	static inline void check_blkcg_changed(struct cfq_io_cq cic, struct bio bio) { }
3561	#endif /* CONFIG_CFQ_GROUP_IOSCHED */
3562
3563	static struct cfq_queue *
3564	cfq_find_alloc_queue(struct cfq_data cfqd, bool is_sync, struct cfq_io_cq cic,
3565	struct bio *bio, gfp_t gfp_mask)
3566	{
3567	struct blkcg *blkcg;
3568	struct cfq_queue cfqq, new_cfqq = NULL;
3569	struct cfq_group *cfqg;
3570
3571	retry:
3572	rcu_read_lock();
3573
3574	blkcg = bio_blkcg(bio);
3575	cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
3576	cfqq = cic_to_cfqq(cic, is_sync);
3577
3578	/*
3579	* Always try a new alloc if we fell back to the OOM cfqq
3580	* originally, since it should just be a temporary situation.
3581	*/
3582	if (!cfqq \|\| cfqq == &cfqd->oom_cfqq) {
3583	cfqq = NULL;
3584	if (new_cfqq) {
3585	cfqq = new_cfqq;
3586	new_cfqq = NULL;
3587	} else if (gfp_mask & __GFP_WAIT) {
3588	rcu_read_unlock();
3589	spin_unlock_irq(cfqd->queue->queue_lock);
3590	new_cfqq = kmem_cache_alloc_node(cfq_pool,
3591	gfp_mask \| __GFP_ZERO,
3592	cfqd->queue->node);
3593	spin_lock_irq(cfqd->queue->queue_lock);
3594	if (new_cfqq)
3595	goto retry;
3596	else
3597	return &cfqd->oom_cfqq;
3598	} else {
3599	cfqq = kmem_cache_alloc_node(cfq_pool,
3600	gfp_mask \| __GFP_ZERO,
3601	cfqd->queue->node);
3602	}
3603
3604	if (cfqq) {
3605	cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3606	cfq_init_prio_data(cfqq, cic);
3607	cfq_link_cfqq_cfqg(cfqq, cfqg);
3608	cfq_log_cfqq(cfqd, cfqq, "alloced");
3609	} else
3610	cfqq = &cfqd->oom_cfqq;
3611	}
3612
3613	if (new_cfqq)
3614	kmem_cache_free(cfq_pool, new_cfqq);
3615
3616	rcu_read_unlock();
3617	return cfqq;
3618	}
3619
3620	static struct cfq_queue **
3621	cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3622	{
3623	switch (ioprio_class) {
3624	case IOPRIO_CLASS_RT:
3625	return &cfqd->async_cfqq[0][ioprio];
3626	case IOPRIO_CLASS_NONE:
3627	ioprio = IOPRIO_NORM;
3628	/* fall through */
3629	case IOPRIO_CLASS_BE:
3630	return &cfqd->async_cfqq[1][ioprio];
3631	case IOPRIO_CLASS_IDLE:
3632	return &cfqd->async_idle_cfqq;
3633	default:
3634	BUG();
3635	}
3636	}
3637
3638	static struct cfq_queue *
3639	cfq_get_queue(struct cfq_data cfqd, bool is_sync, struct cfq_io_cq cic,
3640	struct bio *bio, gfp_t gfp_mask)
3641	{
3642	const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3643	const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3644	struct cfq_queue **async_cfqq = NULL;
3645	struct cfq_queue *cfqq = NULL;
3646
3647	if (!is_sync) {
3648	async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3649	cfqq = *async_cfqq;
3650	}
3651
3652	if (!cfqq)
3653	cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
3654
3655	/*
3656	* pin the queue now that it's allocated, scheduler exit will prune it
3657	*/
3658	if (!is_sync && !(*async_cfqq)) {
3659	cfqq->ref++;
3660	*async_cfqq = cfqq;
3661	}
3662
3663	cfqq->ref++;
3664	return cfqq;
3665	}
3666
3667	static void
3668	__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3669	{
3670	unsigned long elapsed = jiffies - ttime->last_end_request;
3671	elapsed = min(elapsed, 2UL * slice_idle);
3672
3673	ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3674	ttime->ttime_total = (7ttime->ttime_total + 256elapsed) / 8;
3675	ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3676	}
3677
3678	static void
3679	cfq_update_io_thinktime(struct cfq_data cfqd, struct cfq_queue cfqq,
3680	struct cfq_io_cq *cic)
3681	{
3682	if (cfq_cfqq_sync(cfqq)) {
3683	__cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3684	__cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3685	cfqd->cfq_slice_idle);
3686	}
3687	#ifdef CONFIG_CFQ_GROUP_IOSCHED
3688	__cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3689	#endif
3690	}
3691
3692	static void
3693	cfq_update_io_seektime(struct cfq_data cfqd, struct cfq_queue cfqq,
3694	struct request *rq)
3695	{
3696	sector_t sdist = 0;
3697	sector_t n_sec = blk_rq_sectors(rq);
3698	if (cfqq->last_request_pos) {
3699	if (cfqq->last_request_pos < blk_rq_pos(rq))
3700	sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3701	else
3702	sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3703	}
3704
3705	cfqq->seek_history <<= 1;
3706	if (blk_queue_nonrot(cfqd->queue))
3707	cfqq->seek_history \|= (n_sec < CFQQ_SECT_THR_NONROT);
3708	else
3709	cfqq->seek_history \|= (sdist > CFQQ_SEEK_THR);
3710	}
3711
3712	/*
3713	* Disable idle window if the process thinks too long or seeks so much that
3714	* it doesn't matter
3715	*/
3716	static void
3717	cfq_update_idle_window(struct cfq_data cfqd, struct cfq_queue cfqq,
3718	struct cfq_io_cq *cic)
3719	{
3720	int old_idle, enable_idle;
3721
3722	/*
3723	* Don't idle for async or idle io prio class
3724	*/
3725	if (!cfq_cfqq_sync(cfqq) \|\| cfq_class_idle(cfqq))
3726	return;
3727
3728	enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3729
3730	if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3731	cfq_mark_cfqq_deep(cfqq);
3732
3733	if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3734	enable_idle = 0;
3735	else if (!atomic_read(&cic->icq.ioc->active_ref) \|\|
3736	!cfqd->cfq_slice_idle \|\|
3737	(!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3738	enable_idle = 0;
3739	else if (sample_valid(cic->ttime.ttime_samples)) {
3740	if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3741	enable_idle = 0;
3742	else
3743	enable_idle = 1;
3744	}
3745
3746	if (old_idle != enable_idle) {
3747	cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3748	if (enable_idle)
3749	cfq_mark_cfqq_idle_window(cfqq);
3750	else
3751	cfq_clear_cfqq_idle_window(cfqq);
3752	}
3753	}
3754
3755	/*
3756	* Check if new_cfqq should preempt the currently active queue. Return 0 for
3757	* no or if we aren't sure, a 1 will cause a preempt.
3758	*/
3759	static bool
3760	cfq_should_preempt(struct cfq_data cfqd, struct cfq_queue new_cfqq,
3761	struct request *rq)
3762	{
3763	struct cfq_queue *cfqq;
3764
3765	cfqq = cfqd->active_queue;
3766	if (!cfqq)
3767	return false;
3768
3769	if (cfq_class_idle(new_cfqq))
3770	return false;
3771
3772	if (cfq_class_idle(cfqq))
3773	return true;
3774
3775	/*
3776	* Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3777	*/
3778	if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3779	return false;
3780
3781	/*
3782	* if the new request is sync, but the currently running queue is
3783	* not, let the sync request have priority.
3784	*/
3785	if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3786	return true;
3787
3788	if (new_cfqq->cfqg != cfqq->cfqg)
3789	return false;
3790
3791	if (cfq_slice_used(cfqq))
3792	return true;
3793
3794	/* Allow preemption only if we are idling on sync-noidle tree */
3795	if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
3796	cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3797	new_cfqq->service_tree->count == 2 &&
3798	RB_EMPTY_ROOT(&cfqq->sort_list))
3799	return true;
3800
3801	/*
3802	* So both queues are sync. Let the new request get disk time if
3803	* it's a metadata request and the current queue is doing regular IO.
3804	*/
3805	if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3806	return true;
3807
3808	/*
3809	* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3810	*/
3811	if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3812	return true;
3813
3814	/* An idle queue should not be idle now for some reason */
3815	if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3816	return true;
3817
3818	if (!cfqd->active_cic \|\| !cfq_cfqq_wait_request(cfqq))
3819	return false;
3820
3821	/*
3822	* if this request is as-good as one we would expect from the
3823	* current cfqq, let it preempt
3824	*/
3825	if (cfq_rq_close(cfqd, cfqq, rq))
3826	return true;
3827
3828	return false;
3829	}
3830
3831	/*
3832	* cfqq preempts the active queue. if we allowed preempt with no slice left,
3833	* let it have half of its nominal slice.
3834	*/
3835	static void cfq_preempt_queue(struct cfq_data cfqd, struct cfq_queue cfqq)
3836	{
3837	enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3838
3839	cfq_log_cfqq(cfqd, cfqq, "preempt");
3840	cfq_slice_expired(cfqd, 1);
3841
3842	/*
3843	* workload type is changed, don't save slice, otherwise preempt
3844	* doesn't happen
3845	*/
3846	if (old_type != cfqq_type(cfqq))
3847	cfqq->cfqg->saved_wl_slice = 0;
3848
3849	/*
3850	* Put the new queue at the front of the of the current list,
3851	* so we know that it will be selected next.
3852	*/
3853	BUG_ON(!cfq_cfqq_on_rr(cfqq));
3854
3855	cfq_service_tree_add(cfqd, cfqq, 1);
3856
3857	cfqq->slice_end = 0;
3858	cfq_mark_cfqq_slice_new(cfqq);
3859	}
3860
3861	/*
3862	* Called when a new fs request (rq) is added (to cfqq). Check if there's
3863	* something we should do about it
3864	*/
3865	static void
3866	cfq_rq_enqueued(struct cfq_data cfqd, struct cfq_queue cfqq,
3867	struct request *rq)
3868	{
3869	struct cfq_io_cq *cic = RQ_CIC(rq);
3870
3871	cfqd->rq_queued++;
3872	if (rq->cmd_flags & REQ_PRIO)
3873	cfqq->prio_pending++;
3874
3875	cfq_update_io_thinktime(cfqd, cfqq, cic);
3876	cfq_update_io_seektime(cfqd, cfqq, rq);
3877	cfq_update_idle_window(cfqd, cfqq, cic);
3878
3879	cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3880
3881	if (cfqq == cfqd->active_queue) {
3882	/*
3883	* Remember that we saw a request from this process, but
3884	* don't start queuing just yet. Otherwise we risk seeing lots
3885	* of tiny requests, because we disrupt the normal plugging
3886	* and merging. If the request is already larger than a single
3887	* page, let it rip immediately. For that case we assume that
3888	* merging is already done. Ditto for a busy system that
3889	* has other work pending, don't risk delaying until the
3890	* idle timer unplug to continue working.
3891	*/
3892	if (cfq_cfqq_wait_request(cfqq)) {
3893	if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE \|\|
3894	cfqd->busy_queues > 1) {
3895	cfq_del_timer(cfqd, cfqq);
3896	cfq_clear_cfqq_wait_request(cfqq);
3897	__blk_run_queue(cfqd->queue);
3898	} else {
3899	cfqg_stats_update_idle_time(cfqq->cfqg);
3900	cfq_mark_cfqq_must_dispatch(cfqq);
3901	}
3902	}
3903	} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3904	/*
3905	* not the active queue - expire current slice if it is
3906	* idle and has expired it's mean thinktime or this new queue
3907	* has some old slice time left and is of higher priority or
3908	* this new queue is RT and the current one is BE
3909	*/
3910	cfq_preempt_queue(cfqd, cfqq);
3911	__blk_run_queue(cfqd->queue);
3912	}
3913	}
3914
3915	static void cfq_insert_request(struct request_queue q, struct request rq)
3916	{
3917	struct cfq_data *cfqd = q->elevator->elevator_data;
3918	struct cfq_queue *cfqq = RQ_CFQQ(rq);
3919
3920	cfq_log_cfqq(cfqd, cfqq, "insert_request");
3921	cfq_init_prio_data(cfqq, RQ_CIC(rq));
3922
3923	rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3924	list_add_tail(&rq->queuelist, &cfqq->fifo);
3925	cfq_add_rq_rb(rq);
3926	cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3927	rq->cmd_flags);
3928	cfq_rq_enqueued(cfqd, cfqq, rq);
3929	}
3930
3931	/*
3932	* Update hw_tag based on peak queue depth over 50 samples under
3933	* sufficient load.
3934	*/
3935	static void cfq_update_hw_tag(struct cfq_data *cfqd)
3936	{
3937	struct cfq_queue *cfqq = cfqd->active_queue;
3938
3939	if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3940	cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3941
3942	if (cfqd->hw_tag == 1)
3943	return;
3944
3945	if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3946	cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3947	return;
3948
3949	/*
3950	* If active queue hasn't enough requests and can idle, cfq might not
3951	* dispatch sufficient requests to hardware. Don't zero hw_tag in this
3952	* case
3953	*/
3954	if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3955	cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3956	CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3957	return;
3958
3959	if (cfqd->hw_tag_samples++ < 50)
3960	return;
3961
3962	if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3963	cfqd->hw_tag = 1;
3964	else
3965	cfqd->hw_tag = 0;
3966	}
3967
3968	static bool cfq_should_wait_busy(struct cfq_data cfqd, struct cfq_queue cfqq)
3969	{
3970	struct cfq_io_cq *cic = cfqd->active_cic;
3971
3972	/* If the queue already has requests, don't wait */
3973	if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3974	return false;
3975
3976	/* If there are other queues in the group, don't wait */
3977	if (cfqq->cfqg->nr_cfqq > 1)
3978	return false;
3979
3980	/* the only queue in the group, but think time is big */
3981	if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3982	return false;
3983
3984	if (cfq_slice_used(cfqq))
3985	return true;
3986
3987	/* if slice left is less than think time, wait busy */
3988	if (cic && sample_valid(cic->ttime.ttime_samples)
3989	&& (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3990	return true;
3991
3992	/*
3993	* If think times is less than a jiffy than ttime_mean=0 and above
3994	* will not be true. It might happen that slice has not expired yet
3995	* but will expire soon (4-5 ns) during select_queue(). To cover the
3996	* case where think time is less than a jiffy, mark the queue wait
3997	* busy if only 1 jiffy is left in the slice.
3998	*/
3999	if (cfqq->slice_end - jiffies == 1)
4000	return true;
4001
4002	return false;
4003	}
4004
4005	static void cfq_completed_request(struct request_queue q, struct request rq)
4006	{
4007	struct cfq_queue *cfqq = RQ_CFQQ(rq);
4008	struct cfq_data *cfqd = cfqq->cfqd;
4009	const int sync = rq_is_sync(rq);
4010	unsigned long now;
4011
4012	now = jiffies;
4013	cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
4014	!!(rq->cmd_flags & REQ_NOIDLE));
4015
4016	cfq_update_hw_tag(cfqd);
4017
4018	WARN_ON(!cfqd->rq_in_driver);
4019	WARN_ON(!cfqq->dispatched);
4020	cfqd->rq_in_driver--;
4021	cfqq->dispatched--;
4022	(RQ_CFQG(rq))->dispatched--;
4023	cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
4024	rq_io_start_time_ns(rq), rq->cmd_flags);
4025
4026	cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
4027
4028	if (sync) {
4029	struct cfq_rb_root *st;
4030
4031	RQ_CIC(rq)->ttime.last_end_request = now;
4032
4033	if (cfq_cfqq_on_rr(cfqq))
4034	st = cfqq->service_tree;
4035	else
4036	st = st_for(cfqq->cfqg, cfqq_class(cfqq),
4037	cfqq_type(cfqq));
4038
4039	st->ttime.last_end_request = now;
4040	if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
4041	cfqd->last_delayed_sync = now;
4042	}
4043
4044	#ifdef CONFIG_CFQ_GROUP_IOSCHED
4045	cfqq->cfqg->ttime.last_end_request = now;
4046	#endif
4047
4048	/*
4049	* If this is the active queue, check if it needs to be expired,
4050	* or if we want to idle in case it has no pending requests.
4051	*/
4052	if (cfqd->active_queue == cfqq) {
4053	const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
4054
4055	if (cfq_cfqq_slice_new(cfqq)) {
4056	cfq_set_prio_slice(cfqd, cfqq);
4057	cfq_clear_cfqq_slice_new(cfqq);
4058	}
4059
4060	/*
4061	* Should we wait for next request to come in before we expire
4062	* the queue.
4063	*/
4064	if (cfq_should_wait_busy(cfqd, cfqq)) {
4065	unsigned long extend_sl = cfqd->cfq_slice_idle;
4066	if (!cfqd->cfq_slice_idle)
4067	extend_sl = cfqd->cfq_group_idle;
4068	cfqq->slice_end = jiffies + extend_sl;
4069	cfq_mark_cfqq_wait_busy(cfqq);
4070	cfq_log_cfqq(cfqd, cfqq, "will busy wait");
4071	}
4072
4073	/*
4074	* Idling is not enabled on:
4075	* - expired queues
4076	* - idle-priority queues
4077	* - async queues
4078	* - queues with still some requests queued
4079	* - when there is a close cooperator
4080	*/
4081	if (cfq_slice_used(cfqq) \|\| cfq_class_idle(cfqq))
4082	cfq_slice_expired(cfqd, 1);
4083	else if (sync && cfqq_empty &&
4084	!cfq_close_cooperator(cfqd, cfqq)) {
4085	cfq_arm_slice_timer(cfqd);
4086	}
4087	}
4088
4089	if (!cfqd->rq_in_driver)
4090	cfq_schedule_dispatch(cfqd);
4091	}
4092
4093	static inline int __cfq_may_queue(struct cfq_queue *cfqq)
4094	{
4095	if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
4096	cfq_mark_cfqq_must_alloc_slice(cfqq);
4097	return ELV_MQUEUE_MUST;
4098	}
4099
4100	return ELV_MQUEUE_MAY;
4101	}
4102
4103	static int cfq_may_queue(struct request_queue *q, int rw)
4104	{
4105	struct cfq_data *cfqd = q->elevator->elevator_data;
4106	struct task_struct *tsk = current;
4107	struct cfq_io_cq *cic;
4108	struct cfq_queue *cfqq;
4109
4110	/*
4111	* don't force setup of a queue from here, as a call to may_queue
4112	* does not necessarily imply that a request actually will be queued.
4113	* so just lookup a possibly existing queue, or return 'may queue'
4114	* if that fails
4115	*/
4116	cic = cfq_cic_lookup(cfqd, tsk->io_context);
4117	if (!cic)
4118	return ELV_MQUEUE_MAY;
4119
4120	cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
4121	if (cfqq) {
4122	cfq_init_prio_data(cfqq, cic);
4123
4124	return __cfq_may_queue(cfqq);
4125	}
4126
4127	return ELV_MQUEUE_MAY;
4128	}
4129
4130	/*
4131	* queue lock held here
4132	*/
4133	static void cfq_put_request(struct request *rq)
4134	{
4135	struct cfq_queue *cfqq = RQ_CFQQ(rq);
4136
4137	if (cfqq) {
4138	const int rw = rq_data_dir(rq);
4139
4140	BUG_ON(!cfqq->allocated[rw]);
4141	cfqq->allocated[rw]--;
4142
4143	/* Put down rq reference on cfqg */
4144	cfqg_put(RQ_CFQG(rq));
4145	rq->elv.priv[0] = NULL;
4146	rq->elv.priv[1] = NULL;
4147
4148	cfq_put_queue(cfqq);
4149	}
4150	}
4151
4152	static struct cfq_queue *
4153	cfq_merge_cfqqs(struct cfq_data cfqd, struct cfq_io_cq cic,
4154	struct cfq_queue *cfqq)
4155	{
4156	cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
4157	cic_set_cfqq(cic, cfqq->new_cfqq, 1);
4158	cfq_mark_cfqq_coop(cfqq->new_cfqq);
4159	cfq_put_queue(cfqq);
4160	return cic_to_cfqq(cic, 1);
4161	}
4162
4163	/*
4164	* Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4165	* was the last process referring to said cfqq.
4166	*/
4167	static struct cfq_queue *
4168	split_cfqq(struct cfq_io_cq cic, struct cfq_queue cfqq)
4169	{
4170	if (cfqq_process_refs(cfqq) == 1) {
4171	cfqq->pid = current->pid;
4172	cfq_clear_cfqq_coop(cfqq);
4173	cfq_clear_cfqq_split_coop(cfqq);
4174	return cfqq;
4175	}
4176
4177	cic_set_cfqq(cic, NULL, 1);
4178
4179	cfq_put_cooperator(cfqq);
4180
4181	cfq_put_queue(cfqq);
4182	return NULL;
4183	}
4184	/*
4185	* Allocate cfq data structures associated with this request.
4186	*/
4187	static int
4188	cfq_set_request(struct request_queue q, struct request rq, struct bio *bio,
4189	gfp_t gfp_mask)
4190	{
4191	struct cfq_data *cfqd = q->elevator->elevator_data;
4192	struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
4193	const int rw = rq_data_dir(rq);
4194	const bool is_sync = rq_is_sync(rq);
4195	struct cfq_queue *cfqq;
4196
4197	might_sleep_if(gfp_mask & __GFP_WAIT);
4198
4199	spin_lock_irq(q->queue_lock);
4200
4201	check_ioprio_changed(cic, bio);
4202	check_blkcg_changed(cic, bio);
4203	new_queue:
4204	cfqq = cic_to_cfqq(cic, is_sync);
4205	if (!cfqq \|\| cfqq == &cfqd->oom_cfqq) {
4206	cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
4207	cic_set_cfqq(cic, cfqq, is_sync);
4208	} else {
4209	/*
4210	* If the queue was seeky for too long, break it apart.
4211	*/
4212	if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
4213	cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
4214	cfqq = split_cfqq(cic, cfqq);
4215	if (!cfqq)
4216	goto new_queue;
4217	}
4218
4219	/*
4220	* Check to see if this queue is scheduled to merge with
4221	* another, closely cooperating queue. The merging of
4222	* queues happens here as it must be done in process context.
4223	* The reference on new_cfqq was taken in merge_cfqqs.
4224	*/
4225	if (cfqq->new_cfqq)
4226	cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
4227	}
4228
4229	cfqq->allocated[rw]++;
4230
4231	cfqq->ref++;
4232	cfqg_get(cfqq->cfqg);
4233	rq->elv.priv[0] = cfqq;
4234	rq->elv.priv[1] = cfqq->cfqg;
4235	spin_unlock_irq(q->queue_lock);
4236	return 0;
4237	}
4238
4239	static void cfq_kick_queue(struct work_struct *work)
4240	{
4241	struct cfq_data *cfqd =
4242	container_of(work, struct cfq_data, unplug_work);
4243	struct request_queue *q = cfqd->queue;
4244
4245	spin_lock_irq(q->queue_lock);
4246	__blk_run_queue(cfqd->queue);
4247	spin_unlock_irq(q->queue_lock);
4248	}
4249
4250	/*
4251	* Timer running if the active_queue is currently idling inside its time slice
4252	*/
4253	static void cfq_idle_slice_timer(unsigned long data)
4254	{
4255	struct cfq_data cfqd = (struct cfq_data ) data;
4256	struct cfq_queue *cfqq;
4257	unsigned long flags;
4258	int timed_out = 1;
4259
4260	cfq_log(cfqd, "idle timer fired");
4261
4262	spin_lock_irqsave(cfqd->queue->queue_lock, flags);
4263
4264	cfqq = cfqd->active_queue;
4265	if (cfqq) {
4266	timed_out = 0;
4267
4268	/*
4269	* We saw a request before the queue expired, let it through
4270	*/
4271	if (cfq_cfqq_must_dispatch(cfqq))
4272	goto out_kick;
4273
4274	/*
4275	* expired
4276	*/
4277	if (cfq_slice_used(cfqq))
4278	goto expire;
4279
4280	/*
4281	* only expire and reinvoke request handler, if there are
4282	* other queues with pending requests
4283	*/
4284	if (!cfqd->busy_queues)
4285	goto out_cont;
4286
4287	/*
4288	* not expired and it has a request pending, let it dispatch
4289	*/
4290	if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4291	goto out_kick;
4292
4293	/*
4294	* Queue depth flag is reset only when the idle didn't succeed
4295	*/
4296	cfq_clear_cfqq_deep(cfqq);
4297	}
4298	expire:
4299	cfq_slice_expired(cfqd, timed_out);
4300	out_kick:
4301	cfq_schedule_dispatch(cfqd);
4302	out_cont:
4303	spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
4304	}
4305
4306	static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
4307	{
4308	del_timer_sync(&cfqd->idle_slice_timer);
4309	cancel_work_sync(&cfqd->unplug_work);
4310	}
4311
4312	static void cfq_put_async_queues(struct cfq_data *cfqd)
4313	{
4314	int i;
4315
4316	for (i = 0; i < IOPRIO_BE_NR; i++) {
4317	if (cfqd->async_cfqq[0][i])
4318	cfq_put_queue(cfqd->async_cfqq[0][i]);
4319	if (cfqd->async_cfqq[1][i])
4320	cfq_put_queue(cfqd->async_cfqq[1][i]);
4321	}
4322
4323	if (cfqd->async_idle_cfqq)
4324	cfq_put_queue(cfqd->async_idle_cfqq);
4325	}
4326
4327	static void cfq_exit_queue(struct elevator_queue *e)
4328	{
4329	struct cfq_data *cfqd = e->elevator_data;
4330	struct request_queue *q = cfqd->queue;
4331
4332	cfq_shutdown_timer_wq(cfqd);
4333
4334	spin_lock_irq(q->queue_lock);
4335
4336	if (cfqd->active_queue)
4337	__cfq_slice_expired(cfqd, cfqd->active_queue, 0);
4338
4339	cfq_put_async_queues(cfqd);
4340
4341	spin_unlock_irq(q->queue_lock);
4342
4343	cfq_shutdown_timer_wq(cfqd);
4344
4345	#ifdef CONFIG_CFQ_GROUP_IOSCHED
4346	blkcg_deactivate_policy(q, &blkcg_policy_cfq);
4347	#else
4348	kfree(cfqd->root_group);
4349	#endif
4350	kfree(cfqd);
4351	}
4352
4353	static int cfq_init_queue(struct request_queue *q)
4354	{
4355	struct cfq_data *cfqd;
4356	struct blkcg_gq *blkg __maybe_unused;
4357	int i, ret;
4358
4359	cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL \| __GFP_ZERO, q->node);
4360	if (!cfqd)
4361	return -ENOMEM;
4362
4363	cfqd->queue = q;
4364	q->elevator->elevator_data = cfqd;
4365
4366	/* Init root service tree */
4367	cfqd->grp_service_tree = CFQ_RB_ROOT;
4368
4369	/* Init root group and prefer root group over other groups by default */
4370	#ifdef CONFIG_CFQ_GROUP_IOSCHED
4371	ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
4372	if (ret)
4373	goto out_free;
4374
4375	cfqd->root_group = blkg_to_cfqg(q->root_blkg);
4376	#else
4377	ret = -ENOMEM;
4378	cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
4379	GFP_KERNEL, cfqd->queue->node);
4380	if (!cfqd->root_group)
4381	goto out_free;
4382
4383	cfq_init_cfqg_base(cfqd->root_group);
4384	#endif
4385	cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
4386	cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
4387
4388	/*
4389	* Not strictly needed (since RB_ROOT just clears the node and we
4390	* zeroed cfqd on alloc), but better be safe in case someone decides
4391	* to add magic to the rb code
4392	*/
4393	for (i = 0; i < CFQ_PRIO_LISTS; i++)
4394	cfqd->prio_trees[i] = RB_ROOT;
4395
4396	/*
4397	* Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4398	* Grab a permanent reference to it, so that the normal code flow
4399	* will not attempt to free it. oom_cfqq is linked to root_group
4400	* but shouldn't hold a reference as it'll never be unlinked. Lose
4401	* the reference from linking right away.
4402	*/
4403	cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4404	cfqd->oom_cfqq.ref++;
4405
4406	spin_lock_irq(q->queue_lock);
4407	cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4408	cfqg_put(cfqd->root_group);
4409	spin_unlock_irq(q->queue_lock);
4410
4411	init_timer(&cfqd->idle_slice_timer);
4412	cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4413	cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4414
4415	INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4416
4417	cfqd->cfq_quantum = cfq_quantum;
4418	cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4419	cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4420	cfqd->cfq_back_max = cfq_back_max;
4421	cfqd->cfq_back_penalty = cfq_back_penalty;
4422	cfqd->cfq_slice[0] = cfq_slice_async;
4423	cfqd->cfq_slice[1] = cfq_slice_sync;
4424	cfqd->cfq_target_latency = cfq_target_latency;
4425	cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4426	cfqd->cfq_slice_idle = cfq_slice_idle;
4427	cfqd->cfq_group_idle = cfq_group_idle;
4428	cfqd->cfq_latency = 1;
4429	cfqd->hw_tag = -1;
4430	/*
4431	* we optimistically start assuming sync ops weren't delayed in last
4432	* second, in order to have larger depth for async operations.
4433	*/
4434	cfqd->last_delayed_sync = jiffies - HZ;
4435	return 0;
4436
4437	out_free:
4438	kfree(cfqd);
4439	return ret;
4440	}
4441
4442	/*
4443	* sysfs parts below -->
4444	*/
4445	static ssize_t
4446	cfq_var_show(unsigned int var, char *page)
4447	{
4448	return sprintf(page, "%d\n", var);
4449	}
4450
4451	static ssize_t
4452	cfq_var_store(unsigned int var, const char page, size_t count)
4453	{
4454	char p = (char ) page;
4455
4456	*var = simple_strtoul(p, &p, 10);
4457	return count;
4458	}
4459
4460	#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4461	static ssize_t __FUNC(struct elevator_queue e, char page) \
4462	{ \
4463	struct cfq_data *cfqd = e->elevator_data; \
4464	unsigned int __data = __VAR; \
4465	if (__CONV) \
4466	__data = jiffies_to_msecs(__data); \
4467	return cfq_var_show(__data, (page)); \
4468	}
4469	SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4470	SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4471	SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4472	SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4473	SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4474	SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4475	SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4476	SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4477	SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4478	SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4479	SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4480	SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4481	#undef SHOW_FUNCTION
4482
4483	#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4484	static ssize_t __FUNC(struct elevator_queue e, const char page, size_t count) \
4485	{ \
4486	struct cfq_data *cfqd = e->elevator_data; \
4487	unsigned int __data; \
4488	int ret = cfq_var_store(&__data, (page), count); \
4489	if (__data < (MIN)) \
4490	__data = (MIN); \
4491	else if (__data > (MAX)) \
4492	__data = (MAX); \
4493	if (__CONV) \
4494	*(__PTR) = msecs_to_jiffies(__data); \
4495	else \
4496	*(__PTR) = __data; \
4497	return ret; \
4498	}
4499	STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4500	STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4501	UINT_MAX, 1);
4502	STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4503	UINT_MAX, 1);
4504	STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4505	STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4506	UINT_MAX, 0);
4507	STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4508	STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4509	STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4510	STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4511	STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4512	UINT_MAX, 0);
4513	STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4514	STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4515	#undef STORE_FUNCTION
4516
4517	#define CFQ_ATTR(name) \
4518	__ATTR(name, S_IRUGO\|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4519
4520	static struct elv_fs_entry cfq_attrs[] = {
4521	CFQ_ATTR(quantum),
4522	CFQ_ATTR(fifo_expire_sync),
4523	CFQ_ATTR(fifo_expire_async),
4524	CFQ_ATTR(back_seek_max),
4525	CFQ_ATTR(back_seek_penalty),
4526	CFQ_ATTR(slice_sync),
4527	CFQ_ATTR(slice_async),
4528	CFQ_ATTR(slice_async_rq),
4529	CFQ_ATTR(slice_idle),
4530	CFQ_ATTR(group_idle),
4531	CFQ_ATTR(low_latency),
4532	CFQ_ATTR(target_latency),
4533	__ATTR_NULL
4534	};
4535
4536	static struct elevator_type iosched_cfq = {
4537	.ops = {
4538	.elevator_merge_fn = cfq_merge,
4539	.elevator_merged_fn = cfq_merged_request,
4540	.elevator_merge_req_fn = cfq_merged_requests,
4541	.elevator_allow_merge_fn = cfq_allow_merge,
4542	.elevator_bio_merged_fn = cfq_bio_merged,
4543	.elevator_dispatch_fn = cfq_dispatch_requests,
4544	.elevator_add_req_fn = cfq_insert_request,
4545	.elevator_activate_req_fn = cfq_activate_request,
4546	.elevator_deactivate_req_fn = cfq_deactivate_request,
4547	.elevator_completed_req_fn = cfq_completed_request,
4548	.elevator_former_req_fn = elv_rb_former_request,
4549	.elevator_latter_req_fn = elv_rb_latter_request,
4550	.elevator_init_icq_fn = cfq_init_icq,
4551	.elevator_exit_icq_fn = cfq_exit_icq,
4552	.elevator_set_req_fn = cfq_set_request,
4553	.elevator_put_req_fn = cfq_put_request,
4554	.elevator_may_queue_fn = cfq_may_queue,
4555	.elevator_init_fn = cfq_init_queue,
4556	.elevator_exit_fn = cfq_exit_queue,
4557	},
4558	.icq_size = sizeof(struct cfq_io_cq),
4559	.icq_align = __alignof__(struct cfq_io_cq),
4560	.elevator_attrs = cfq_attrs,
4561	.elevator_name = "cfq",
4562	.elevator_owner = THIS_MODULE,
4563	};
4564
4565	#ifdef CONFIG_CFQ_GROUP_IOSCHED
4566	static struct blkcg_policy blkcg_policy_cfq = {
4567	.pd_size = sizeof(struct cfq_group),
4568	.cftypes = cfq_blkcg_files,
4569
4570	.pd_init_fn = cfq_pd_init,
4571	.pd_offline_fn = cfq_pd_offline,
4572	.pd_reset_stats_fn = cfq_pd_reset_stats,
4573	};
4574	#endif
4575
4576	static int __init cfq_init(void)
4577	{
4578	int ret;
4579
4580	/*
4581	* could be 0 on HZ < 1000 setups
4582	*/
4583	if (!cfq_slice_async)
4584	cfq_slice_async = 1;
4585	if (!cfq_slice_idle)
4586	cfq_slice_idle = 1;
4587
4588	#ifdef CONFIG_CFQ_GROUP_IOSCHED
4589	if (!cfq_group_idle)
4590	cfq_group_idle = 1;
4591
4592	ret = blkcg_policy_register(&blkcg_policy_cfq);
4593	if (ret)
4594	return ret;
4595	#else
4596	cfq_group_idle = 0;
4597	#endif
4598
4599	ret = -ENOMEM;
4600	cfq_pool = KMEM_CACHE(cfq_queue, 0);
4601	if (!cfq_pool)
4602	goto err_pol_unreg;
4603
4604	ret = elv_register(&iosched_cfq);
4605	if (ret)
4606	goto err_free_pool;
4607
4608	return 0;
4609
4610	err_free_pool:
4611	kmem_cache_destroy(cfq_pool);
4612	err_pol_unreg:
4613	#ifdef CONFIG_CFQ_GROUP_IOSCHED
4614	blkcg_policy_unregister(&blkcg_policy_cfq);
4615	#endif
4616	return ret;
4617	}
4618
4619	static void __exit cfq_exit(void)
4620	{
4621	#ifdef CONFIG_CFQ_GROUP_IOSCHED
4622	blkcg_policy_unregister(&blkcg_policy_cfq);
4623	#endif
4624	elv_unregister(&iosched_cfq);
4625	kmem_cache_destroy(cfq_pool);
4626	}
4627
4628	module_init(cfq_init);
4629	module_exit(cfq_exit);
4630
4631	MODULE_AUTHOR("Jens Axboe");
4632	MODULE_LICENSE("GPL");
4633	MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
4634

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