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-rw-r--r--fs/btrfs/async-thread.c848
1 files changed, 227 insertions, 621 deletions
diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index c1e0b0caf9cc..ecb5832c0967 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -1,5 +1,6 @@
1/* 1/*
2 * Copyright (C) 2007 Oracle. All rights reserved. 2 * Copyright (C) 2007 Oracle. All rights reserved.
3 * Copyright (C) 2014 Fujitsu. All rights reserved.
3 * 4 *
4 * This program is free software; you can redistribute it and/or 5 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public 6 * modify it under the terms of the GNU General Public
@@ -21,708 +22,313 @@
21#include <linux/list.h> 22#include <linux/list.h>
22#include <linux/spinlock.h> 23#include <linux/spinlock.h>
23#include <linux/freezer.h> 24#include <linux/freezer.h>
25#include <linux/workqueue.h>
24#include "async-thread.h" 26#include "async-thread.h"
27#include "ctree.h"
28
29#define WORK_DONE_BIT 0
30#define WORK_ORDER_DONE_BIT 1
31#define WORK_HIGH_PRIO_BIT 2
32
33#define NO_THRESHOLD (-1)
34#define DFT_THRESHOLD (32)
35
36struct __btrfs_workqueue {
37 struct workqueue_struct *normal_wq;
38 /* List head pointing to ordered work list */
39 struct list_head ordered_list;
40
41 /* Spinlock for ordered_list */
42 spinlock_t list_lock;
43
44 /* Thresholding related variants */
45 atomic_t pending;
46 int max_active;
47 int current_max;
48 int thresh;
49 unsigned int count;
50 spinlock_t thres_lock;
51};
25 52
26#define WORK_QUEUED_BIT 0 53struct btrfs_workqueue {
27#define WORK_DONE_BIT 1 54 struct __btrfs_workqueue *normal;
28#define WORK_ORDER_DONE_BIT 2 55 struct __btrfs_workqueue *high;
29#define WORK_HIGH_PRIO_BIT 3 56};
30
31/*
32 * container for the kthread task pointer and the list of pending work
33 * One of these is allocated per thread.
34 */
35struct btrfs_worker_thread {
36 /* pool we belong to */
37 struct btrfs_workers *workers;
38
39 /* list of struct btrfs_work that are waiting for service */
40 struct list_head pending;
41 struct list_head prio_pending;
42
43 /* list of worker threads from struct btrfs_workers */
44 struct list_head worker_list;
45
46 /* kthread */
47 struct task_struct *task;
48 57
49 /* number of things on the pending list */ 58static inline struct __btrfs_workqueue
50 atomic_t num_pending; 59*__btrfs_alloc_workqueue(const char *name, int flags, int max_active,
60 int thresh)
61{
62 struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
51 63
52 /* reference counter for this struct */ 64 if (unlikely(!ret))
53 atomic_t refs; 65 return NULL;
54 66
55 unsigned long sequence; 67 ret->max_active = max_active;
68 atomic_set(&ret->pending, 0);
69 if (thresh == 0)
70 thresh = DFT_THRESHOLD;
71 /* For low threshold, disabling threshold is a better choice */
72 if (thresh < DFT_THRESHOLD) {
73 ret->current_max = max_active;
74 ret->thresh = NO_THRESHOLD;
75 } else {
76 ret->current_max = 1;
77 ret->thresh = thresh;
78 }
56 79
57 /* protects the pending list. */ 80 if (flags & WQ_HIGHPRI)
58 spinlock_t lock; 81 ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
82 ret->max_active,
83 "btrfs", name);
84 else
85 ret->normal_wq = alloc_workqueue("%s-%s", flags,
86 ret->max_active, "btrfs",
87 name);
88 if (unlikely(!ret->normal_wq)) {
89 kfree(ret);
90 return NULL;
91 }
59 92
60 /* set to non-zero when this thread is already awake and kicking */ 93 INIT_LIST_HEAD(&ret->ordered_list);
61 int working; 94 spin_lock_init(&ret->list_lock);
95 spin_lock_init(&ret->thres_lock);
96 trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
97 return ret;
98}
62 99
63 /* are we currently idle */ 100static inline void
64 int idle; 101__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
65};
66 102
67static int __btrfs_start_workers(struct btrfs_workers *workers); 103struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
104 int flags,
105 int max_active,
106 int thresh)
107{
108 struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
68 109
69/* 110 if (unlikely(!ret))
70 * btrfs_start_workers uses kthread_run, which can block waiting for memory 111 return NULL;
71 * for a very long time. It will actually throttle on page writeback,
72 * and so it may not make progress until after our btrfs worker threads
73 * process all of the pending work structs in their queue
74 *
75 * This means we can't use btrfs_start_workers from inside a btrfs worker
76 * thread that is used as part of cleaning dirty memory, which pretty much
77 * involves all of the worker threads.
78 *
79 * Instead we have a helper queue who never has more than one thread
80 * where we scheduler thread start operations. This worker_start struct
81 * is used to contain the work and hold a pointer to the queue that needs
82 * another worker.
83 */
84struct worker_start {
85 struct btrfs_work work;
86 struct btrfs_workers *queue;
87};
88 112
89static void start_new_worker_func(struct btrfs_work *work) 113 ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
90{ 114 max_active, thresh);
91 struct worker_start *start; 115 if (unlikely(!ret->normal)) {
92 start = container_of(work, struct worker_start, work); 116 kfree(ret);
93 __btrfs_start_workers(start->queue); 117 return NULL;
94 kfree(start); 118 }
95}
96 119
97/* 120 if (flags & WQ_HIGHPRI) {
98 * helper function to move a thread onto the idle list after it 121 ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
99 * has finished some requests. 122 thresh);
100 */ 123 if (unlikely(!ret->high)) {
101static void check_idle_worker(struct btrfs_worker_thread *worker) 124 __btrfs_destroy_workqueue(ret->normal);
102{ 125 kfree(ret);
103 if (!worker->idle && atomic_read(&worker->num_pending) < 126 return NULL;
104 worker->workers->idle_thresh / 2) {
105 unsigned long flags;
106 spin_lock_irqsave(&worker->workers->lock, flags);
107 worker->idle = 1;
108
109 /* the list may be empty if the worker is just starting */
110 if (!list_empty(&worker->worker_list) &&
111 !worker->workers->stopping) {
112 list_move(&worker->worker_list,
113 &worker->workers->idle_list);
114 } 127 }
115 spin_unlock_irqrestore(&worker->workers->lock, flags);
116 } 128 }
129 return ret;
117} 130}
118 131
119/* 132/*
120 * helper function to move a thread off the idle list after new 133 * Hook for threshold which will be called in btrfs_queue_work.
121 * pending work is added. 134 * This hook WILL be called in IRQ handler context,
135 * so workqueue_set_max_active MUST NOT be called in this hook
122 */ 136 */
123static void check_busy_worker(struct btrfs_worker_thread *worker) 137static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
124{ 138{
125 if (worker->idle && atomic_read(&worker->num_pending) >= 139 if (wq->thresh == NO_THRESHOLD)
126 worker->workers->idle_thresh) { 140 return;
127 unsigned long flags; 141 atomic_inc(&wq->pending);
128 spin_lock_irqsave(&worker->workers->lock, flags);
129 worker->idle = 0;
130
131 if (!list_empty(&worker->worker_list) &&
132 !worker->workers->stopping) {
133 list_move_tail(&worker->worker_list,
134 &worker->workers->worker_list);
135 }
136 spin_unlock_irqrestore(&worker->workers->lock, flags);
137 }
138} 142}
139 143
140static void check_pending_worker_creates(struct btrfs_worker_thread *worker) 144/*
145 * Hook for threshold which will be called before executing the work,
146 * This hook is called in kthread content.
147 * So workqueue_set_max_active is called here.
148 */
149static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
141{ 150{
142 struct btrfs_workers *workers = worker->workers; 151 int new_max_active;
143 struct worker_start *start; 152 long pending;
144 unsigned long flags; 153 int need_change = 0;
145 154
146 rmb(); 155 if (wq->thresh == NO_THRESHOLD)
147 if (!workers->atomic_start_pending)
148 return; 156 return;
149 157
150 start = kzalloc(sizeof(*start), GFP_NOFS); 158 atomic_dec(&wq->pending);
151 if (!start) 159 spin_lock(&wq->thres_lock);
152 return; 160 /*
153 161 * Use wq->count to limit the calling frequency of
154 start->work.func = start_new_worker_func; 162 * workqueue_set_max_active.
155 start->queue = workers; 163 */
156 164 wq->count++;
157 spin_lock_irqsave(&workers->lock, flags); 165 wq->count %= (wq->thresh / 4);
158 if (!workers->atomic_start_pending) 166 if (!wq->count)
159 goto out; 167 goto out;
160 168 new_max_active = wq->current_max;
161 workers->atomic_start_pending = 0;
162 if (workers->num_workers + workers->num_workers_starting >=
163 workers->max_workers)
164 goto out;
165
166 workers->num_workers_starting += 1;
167 spin_unlock_irqrestore(&workers->lock, flags);
168 btrfs_queue_worker(workers->atomic_worker_start, &start->work);
169 return;
170 169
170 /*
171 * pending may be changed later, but it's OK since we really
172 * don't need it so accurate to calculate new_max_active.
173 */
174 pending = atomic_read(&wq->pending);
175 if (pending > wq->thresh)
176 new_max_active++;
177 if (pending < wq->thresh / 2)
178 new_max_active--;
179 new_max_active = clamp_val(new_max_active, 1, wq->max_active);
180 if (new_max_active != wq->current_max) {
181 need_change = 1;
182 wq->current_max = new_max_active;
183 }
171out: 184out:
172 kfree(start); 185 spin_unlock(&wq->thres_lock);
173 spin_unlock_irqrestore(&workers->lock, flags); 186
187 if (need_change) {
188 workqueue_set_max_active(wq->normal_wq, wq->current_max);
189 }
174} 190}
175 191
176static noinline void run_ordered_completions(struct btrfs_workers *workers, 192static void run_ordered_work(struct __btrfs_workqueue *wq)
177 struct btrfs_work *work)
178{ 193{
179 if (!workers->ordered) 194 struct list_head *list = &wq->ordered_list;
180 return; 195 struct btrfs_work *work;
181 196 spinlock_t *lock = &wq->list_lock;
182 set_bit(WORK_DONE_BIT, &work->flags); 197 unsigned long flags;
183
184 spin_lock(&workers->order_lock);
185 198
186 while (1) { 199 while (1) {
187 if (!list_empty(&workers->prio_order_list)) { 200 spin_lock_irqsave(lock, flags);
188 work = list_entry(workers->prio_order_list.next, 201 if (list_empty(list))
189 struct btrfs_work, order_list);
190 } else if (!list_empty(&workers->order_list)) {
191 work = list_entry(workers->order_list.next,
192 struct btrfs_work, order_list);
193 } else {
194 break; 202 break;
195 } 203 work = list_entry(list->next, struct btrfs_work,
204 ordered_list);
196 if (!test_bit(WORK_DONE_BIT, &work->flags)) 205 if (!test_bit(WORK_DONE_BIT, &work->flags))
197 break; 206 break;
198 207
199 /* we are going to call the ordered done function, but 208 /*
209 * we are going to call the ordered done function, but
200 * we leave the work item on the list as a barrier so 210 * we leave the work item on the list as a barrier so
201 * that later work items that are done don't have their 211 * that later work items that are done don't have their
202 * functions called before this one returns 212 * functions called before this one returns
203 */ 213 */
204 if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags)) 214 if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
205 break; 215 break;
206 216 trace_btrfs_ordered_sched(work);
207 spin_unlock(&workers->order_lock); 217 spin_unlock_irqrestore(lock, flags);
208
209 work->ordered_func(work); 218 work->ordered_func(work);
210 219
211 /* now take the lock again and drop our item from the list */ 220 /* now take the lock again and drop our item from the list */
212 spin_lock(&workers->order_lock); 221 spin_lock_irqsave(lock, flags);
213 list_del(&work->order_list); 222 list_del(&work->ordered_list);
214 spin_unlock(&workers->order_lock); 223 spin_unlock_irqrestore(lock, flags);
215 224
216 /* 225 /*
217 * we don't want to call the ordered free functions 226 * we don't want to call the ordered free functions
218 * with the lock held though 227 * with the lock held though
219 */ 228 */
220 work->ordered_free(work); 229 work->ordered_free(work);
221 spin_lock(&workers->order_lock); 230 trace_btrfs_all_work_done(work);
222 }
223
224 spin_unlock(&workers->order_lock);
225}
226
227static void put_worker(struct btrfs_worker_thread *worker)
228{
229 if (atomic_dec_and_test(&worker->refs))
230 kfree(worker);
231}
232
233static int try_worker_shutdown(struct btrfs_worker_thread *worker)
234{
235 int freeit = 0;
236
237 spin_lock_irq(&worker->lock);
238 spin_lock(&worker->workers->lock);
239 if (worker->workers->num_workers > 1 &&
240 worker->idle &&
241 !worker->working &&
242 !list_empty(&worker->worker_list) &&
243 list_empty(&worker->prio_pending) &&
244 list_empty(&worker->pending) &&
245 atomic_read(&worker->num_pending) == 0) {
246 freeit = 1;
247 list_del_init(&worker->worker_list);
248 worker->workers->num_workers--;
249 } 231 }
250 spin_unlock(&worker->workers->lock); 232 spin_unlock_irqrestore(lock, flags);
251 spin_unlock_irq(&worker->lock);
252
253 if (freeit)
254 put_worker(worker);
255 return freeit;
256} 233}
257 234
258static struct btrfs_work *get_next_work(struct btrfs_worker_thread *worker, 235static void normal_work_helper(struct work_struct *arg)
259 struct list_head *prio_head,
260 struct list_head *head)
261{
262 struct btrfs_work *work = NULL;
263 struct list_head *cur = NULL;
264
265 if (!list_empty(prio_head))
266 cur = prio_head->next;
267
268 smp_mb();
269 if (!list_empty(&worker->prio_pending))
270 goto refill;
271
272 if (!list_empty(head))
273 cur = head->next;
274
275 if (cur)
276 goto out;
277
278refill:
279 spin_lock_irq(&worker->lock);
280 list_splice_tail_init(&worker->prio_pending, prio_head);
281 list_splice_tail_init(&worker->pending, head);
282
283 if (!list_empty(prio_head))
284 cur = prio_head->next;
285 else if (!list_empty(head))
286 cur = head->next;
287 spin_unlock_irq(&worker->lock);
288
289 if (!cur)
290 goto out_fail;
291
292out:
293 work = list_entry(cur, struct btrfs_work, list);
294
295out_fail:
296 return work;
297}
298
299/*
300 * main loop for servicing work items
301 */
302static int worker_loop(void *arg)
303{ 236{
304 struct btrfs_worker_thread *worker = arg;
305 struct list_head head;
306 struct list_head prio_head;
307 struct btrfs_work *work; 237 struct btrfs_work *work;
238 struct __btrfs_workqueue *wq;
239 int need_order = 0;
308 240
309 INIT_LIST_HEAD(&head); 241 work = container_of(arg, struct btrfs_work, normal_work);
310 INIT_LIST_HEAD(&prio_head); 242 /*
311 243 * We should not touch things inside work in the following cases:
312 do { 244 * 1) after work->func() if it has no ordered_free
313again: 245 * Since the struct is freed in work->func().
314 while (1) { 246 * 2) after setting WORK_DONE_BIT
315 247 * The work may be freed in other threads almost instantly.
316 248 * So we save the needed things here.
317 work = get_next_work(worker, &prio_head, &head); 249 */
318 if (!work) 250 if (work->ordered_func)
319 break; 251 need_order = 1;
320 252 wq = work->wq;
321 list_del(&work->list); 253
322 clear_bit(WORK_QUEUED_BIT, &work->flags); 254 trace_btrfs_work_sched(work);
323 255 thresh_exec_hook(wq);
324 work->worker = worker; 256 work->func(work);
325 257 if (need_order) {
326 work->func(work); 258 set_bit(WORK_DONE_BIT, &work->flags);
327 259 run_ordered_work(wq);
328 atomic_dec(&worker->num_pending);
329 /*
330 * unless this is an ordered work queue,
331 * 'work' was probably freed by func above.
332 */
333 run_ordered_completions(worker->workers, work);
334
335 check_pending_worker_creates(worker);
336 cond_resched();
337 }
338
339 spin_lock_irq(&worker->lock);
340 check_idle_worker(worker);
341
342 if (freezing(current)) {
343 worker->working = 0;
344 spin_unlock_irq(&worker->lock);
345 try_to_freeze();
346 } else {
347 spin_unlock_irq(&worker->lock);
348 if (!kthread_should_stop()) {
349 cpu_relax();
350 /*
351 * we've dropped the lock, did someone else
352 * jump_in?
353 */
354 smp_mb();
355 if (!list_empty(&worker->pending) ||
356 !list_empty(&worker->prio_pending))
357 continue;
358
359 /*
360 * this short schedule allows more work to
361 * come in without the queue functions
362 * needing to go through wake_up_process()
363 *
364 * worker->working is still 1, so nobody
365 * is going to try and wake us up
366 */
367 schedule_timeout(1);
368 smp_mb();
369 if (!list_empty(&worker->pending) ||
370 !list_empty(&worker->prio_pending))
371 continue;
372
373 if (kthread_should_stop())
374 break;
375
376 /* still no more work?, sleep for real */
377 spin_lock_irq(&worker->lock);
378 set_current_state(TASK_INTERRUPTIBLE);
379 if (!list_empty(&worker->pending) ||
380 !list_empty(&worker->prio_pending)) {
381 spin_unlock_irq(&worker->lock);
382 set_current_state(TASK_RUNNING);
383 goto again;
384 }
385
386 /*
387 * this makes sure we get a wakeup when someone
388 * adds something new to the queue
389 */
390 worker->working = 0;
391 spin_unlock_irq(&worker->lock);
392
393 if (!kthread_should_stop()) {
394 schedule_timeout(HZ * 120);
395 if (!worker->working &&
396 try_worker_shutdown(worker)) {
397 return 0;
398 }
399 }
400 }
401 __set_current_state(TASK_RUNNING);
402 }
403 } while (!kthread_should_stop());
404 return 0;
405}
406
407/*
408 * this will wait for all the worker threads to shutdown
409 */
410void btrfs_stop_workers(struct btrfs_workers *workers)
411{
412 struct list_head *cur;
413 struct btrfs_worker_thread *worker;
414 int can_stop;
415
416 spin_lock_irq(&workers->lock);
417 workers->stopping = 1;
418 list_splice_init(&workers->idle_list, &workers->worker_list);
419 while (!list_empty(&workers->worker_list)) {
420 cur = workers->worker_list.next;
421 worker = list_entry(cur, struct btrfs_worker_thread,
422 worker_list);
423
424 atomic_inc(&worker->refs);
425 workers->num_workers -= 1;
426 if (!list_empty(&worker->worker_list)) {
427 list_del_init(&worker->worker_list);
428 put_worker(worker);
429 can_stop = 1;
430 } else
431 can_stop = 0;
432 spin_unlock_irq(&workers->lock);
433 if (can_stop)
434 kthread_stop(worker->task);
435 spin_lock_irq(&workers->lock);
436 put_worker(worker);
437 } 260 }
438 spin_unlock_irq(&workers->lock); 261 if (!need_order)
262 trace_btrfs_all_work_done(work);
439} 263}
440 264
441/* 265void btrfs_init_work(struct btrfs_work *work,
442 * simple init on struct btrfs_workers 266 btrfs_func_t func,
443 */ 267 btrfs_func_t ordered_func,
444void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max, 268 btrfs_func_t ordered_free)
445 struct btrfs_workers *async_helper)
446{ 269{
447 workers->num_workers = 0; 270 work->func = func;
448 workers->num_workers_starting = 0; 271 work->ordered_func = ordered_func;
449 INIT_LIST_HEAD(&workers->worker_list); 272 work->ordered_free = ordered_free;
450 INIT_LIST_HEAD(&workers->idle_list); 273 INIT_WORK(&work->normal_work, normal_work_helper);
451 INIT_LIST_HEAD(&workers->order_list); 274 INIT_LIST_HEAD(&work->ordered_list);
452 INIT_LIST_HEAD(&workers->prio_order_list); 275 work->flags = 0;
453 spin_lock_init(&workers->lock);
454 spin_lock_init(&workers->order_lock);
455 workers->max_workers = max;
456 workers->idle_thresh = 32;
457 workers->name = name;
458 workers->ordered = 0;
459 workers->atomic_start_pending = 0;
460 workers->atomic_worker_start = async_helper;
461 workers->stopping = 0;
462} 276}
463 277
464/* 278static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
465 * starts new worker threads. This does not enforce the max worker 279 struct btrfs_work *work)
466 * count in case you need to temporarily go past it.
467 */
468static int __btrfs_start_workers(struct btrfs_workers *workers)
469{ 280{
470 struct btrfs_worker_thread *worker; 281 unsigned long flags;
471 int ret = 0;
472
473 worker = kzalloc(sizeof(*worker), GFP_NOFS);
474 if (!worker) {
475 ret = -ENOMEM;
476 goto fail;
477 }
478
479 INIT_LIST_HEAD(&worker->pending);
480 INIT_LIST_HEAD(&worker->prio_pending);
481 INIT_LIST_HEAD(&worker->worker_list);
482 spin_lock_init(&worker->lock);
483
484 atomic_set(&worker->num_pending, 0);
485 atomic_set(&worker->refs, 1);
486 worker->workers = workers;
487 worker->task = kthread_create(worker_loop, worker,
488 "btrfs-%s-%d", workers->name,
489 workers->num_workers + 1);
490 if (IS_ERR(worker->task)) {
491 ret = PTR_ERR(worker->task);
492 goto fail;
493 }
494 282
495 spin_lock_irq(&workers->lock); 283 work->wq = wq;
496 if (workers->stopping) { 284 thresh_queue_hook(wq);
497 spin_unlock_irq(&workers->lock); 285 if (work->ordered_func) {
498 ret = -EINVAL; 286 spin_lock_irqsave(&wq->list_lock, flags);
499 goto fail_kthread; 287 list_add_tail(&work->ordered_list, &wq->ordered_list);
288 spin_unlock_irqrestore(&wq->list_lock, flags);
500 } 289 }
501 list_add_tail(&worker->worker_list, &workers->idle_list); 290 queue_work(wq->normal_wq, &work->normal_work);
502 worker->idle = 1; 291 trace_btrfs_work_queued(work);
503 workers->num_workers++;
504 workers->num_workers_starting--;
505 WARN_ON(workers->num_workers_starting < 0);
506 spin_unlock_irq(&workers->lock);
507
508 wake_up_process(worker->task);
509 return 0;
510
511fail_kthread:
512 kthread_stop(worker->task);
513fail:
514 kfree(worker);
515 spin_lock_irq(&workers->lock);
516 workers->num_workers_starting--;
517 spin_unlock_irq(&workers->lock);
518 return ret;
519} 292}
520 293
521int btrfs_start_workers(struct btrfs_workers *workers) 294void btrfs_queue_work(struct btrfs_workqueue *wq,
295 struct btrfs_work *work)
522{ 296{
523 spin_lock_irq(&workers->lock); 297 struct __btrfs_workqueue *dest_wq;
524 workers->num_workers_starting++;
525 spin_unlock_irq(&workers->lock);
526 return __btrfs_start_workers(workers);
527}
528
529/*
530 * run through the list and find a worker thread that doesn't have a lot
531 * to do right now. This can return null if we aren't yet at the thread
532 * count limit and all of the threads are busy.
533 */
534static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers)
535{
536 struct btrfs_worker_thread *worker;
537 struct list_head *next;
538 int enforce_min;
539
540 enforce_min = (workers->num_workers + workers->num_workers_starting) <
541 workers->max_workers;
542
543 /*
544 * if we find an idle thread, don't move it to the end of the
545 * idle list. This improves the chance that the next submission
546 * will reuse the same thread, and maybe catch it while it is still
547 * working
548 */
549 if (!list_empty(&workers->idle_list)) {
550 next = workers->idle_list.next;
551 worker = list_entry(next, struct btrfs_worker_thread,
552 worker_list);
553 return worker;
554 }
555 if (enforce_min || list_empty(&workers->worker_list))
556 return NULL;
557
558 /*
559 * if we pick a busy task, move the task to the end of the list.
560 * hopefully this will keep things somewhat evenly balanced.
561 * Do the move in batches based on the sequence number. This groups
562 * requests submitted at roughly the same time onto the same worker.
563 */
564 next = workers->worker_list.next;
565 worker = list_entry(next, struct btrfs_worker_thread, worker_list);
566 worker->sequence++;
567 298
568 if (worker->sequence % workers->idle_thresh == 0) 299 if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
569 list_move_tail(next, &workers->worker_list); 300 dest_wq = wq->high;
570 return worker; 301 else
302 dest_wq = wq->normal;
303 __btrfs_queue_work(dest_wq, work);
571} 304}
572 305
573/* 306static inline void
574 * selects a worker thread to take the next job. This will either find 307__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
575 * an idle worker, start a new worker up to the max count, or just return
576 * one of the existing busy workers.
577 */
578static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers)
579{ 308{
580 struct btrfs_worker_thread *worker; 309 destroy_workqueue(wq->normal_wq);
581 unsigned long flags; 310 trace_btrfs_workqueue_destroy(wq);
582 struct list_head *fallback; 311 kfree(wq);
583 int ret;
584
585 spin_lock_irqsave(&workers->lock, flags);
586again:
587 worker = next_worker(workers);
588
589 if (!worker) {
590 if (workers->num_workers + workers->num_workers_starting >=
591 workers->max_workers) {
592 goto fallback;
593 } else if (workers->atomic_worker_start) {
594 workers->atomic_start_pending = 1;
595 goto fallback;
596 } else {
597 workers->num_workers_starting++;
598 spin_unlock_irqrestore(&workers->lock, flags);
599 /* we're below the limit, start another worker */
600 ret = __btrfs_start_workers(workers);
601 spin_lock_irqsave(&workers->lock, flags);
602 if (ret)
603 goto fallback;
604 goto again;
605 }
606 }
607 goto found;
608
609fallback:
610 fallback = NULL;
611 /*
612 * we have failed to find any workers, just
613 * return the first one we can find.
614 */
615 if (!list_empty(&workers->worker_list))
616 fallback = workers->worker_list.next;
617 if (!list_empty(&workers->idle_list))
618 fallback = workers->idle_list.next;
619 BUG_ON(!fallback);
620 worker = list_entry(fallback,
621 struct btrfs_worker_thread, worker_list);
622found:
623 /*
624 * this makes sure the worker doesn't exit before it is placed
625 * onto a busy/idle list
626 */
627 atomic_inc(&worker->num_pending);
628 spin_unlock_irqrestore(&workers->lock, flags);
629 return worker;
630} 312}
631 313
632/* 314void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
633 * btrfs_requeue_work just puts the work item back on the tail of the list
634 * it was taken from. It is intended for use with long running work functions
635 * that make some progress and want to give the cpu up for others.
636 */
637void btrfs_requeue_work(struct btrfs_work *work)
638{ 315{
639 struct btrfs_worker_thread *worker = work->worker; 316 if (!wq)
640 unsigned long flags;
641 int wake = 0;
642
643 if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
644 return; 317 return;
645 318 if (wq->high)
646 spin_lock_irqsave(&worker->lock, flags); 319 __btrfs_destroy_workqueue(wq->high);
647 if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) 320 __btrfs_destroy_workqueue(wq->normal);
648 list_add_tail(&work->list, &worker->prio_pending); 321 kfree(wq);
649 else
650 list_add_tail(&work->list, &worker->pending);
651 atomic_inc(&worker->num_pending);
652
653 /* by definition we're busy, take ourselves off the idle
654 * list
655 */
656 if (worker->idle) {
657 spin_lock(&worker->workers->lock);
658 worker->idle = 0;
659 list_move_tail(&worker->worker_list,
660 &worker->workers->worker_list);
661 spin_unlock(&worker->workers->lock);
662 }
663 if (!worker->working) {
664 wake = 1;
665 worker->working = 1;
666 }
667
668 if (wake)
669 wake_up_process(worker->task);
670 spin_unlock_irqrestore(&worker->lock, flags);
671} 322}
672 323
673void btrfs_set_work_high_prio(struct btrfs_work *work) 324void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
674{ 325{
675 set_bit(WORK_HIGH_PRIO_BIT, &work->flags); 326 wq->normal->max_active = max;
327 if (wq->high)
328 wq->high->max_active = max;
676} 329}
677 330
678/* 331void btrfs_set_work_high_priority(struct btrfs_work *work)
679 * places a struct btrfs_work into the pending queue of one of the kthreads
680 */
681void btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
682{ 332{
683 struct btrfs_worker_thread *worker; 333 set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
684 unsigned long flags;
685 int wake = 0;
686
687 /* don't requeue something already on a list */
688 if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
689 return;
690
691 worker = find_worker(workers);
692 if (workers->ordered) {
693 /*
694 * you're not allowed to do ordered queues from an
695 * interrupt handler
696 */
697 spin_lock(&workers->order_lock);
698 if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) {
699 list_add_tail(&work->order_list,
700 &workers->prio_order_list);
701 } else {
702 list_add_tail(&work->order_list, &workers->order_list);
703 }
704 spin_unlock(&workers->order_lock);
705 } else {
706 INIT_LIST_HEAD(&work->order_list);
707 }
708
709 spin_lock_irqsave(&worker->lock, flags);
710
711 if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags))
712 list_add_tail(&work->list, &worker->prio_pending);
713 else
714 list_add_tail(&work->list, &worker->pending);
715 check_busy_worker(worker);
716
717 /*
718 * avoid calling into wake_up_process if this thread has already
719 * been kicked
720 */
721 if (!worker->working)
722 wake = 1;
723 worker->working = 1;
724
725 if (wake)
726 wake_up_process(worker->task);
727 spin_unlock_irqrestore(&worker->lock, flags);
728} 334}
generated by cgit v1.2.2 (git 2.25.0) at 2025-10-03 15:01:32 -0400