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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007 Oracle. All rights reserved.
4 * Copyright (C) 2014 Fujitsu. All rights reserved.
5 */
6
7#include <linux/kthread.h>
8#include <linux/slab.h>
9#include <linux/list.h>
10#include <linux/spinlock.h>
11#include <linux/freezer.h>
12#include "async-thread.h"
13#include "ctree.h"
14
15enum {
16 WORK_DONE_BIT,
17 WORK_ORDER_DONE_BIT,
18 WORK_HIGH_PRIO_BIT,
19};
20
21#define NO_THRESHOLD (-1)
22#define DFT_THRESHOLD (32)
23
24struct __btrfs_workqueue {
25 struct workqueue_struct *normal_wq;
26
27 /* File system this workqueue services */
28 struct btrfs_fs_info *fs_info;
29
30 /* List head pointing to ordered work list */
31 struct list_head ordered_list;
32
33 /* Spinlock for ordered_list */
34 spinlock_t list_lock;
35
36 /* Thresholding related variants */
37 atomic_t pending;
38
39 /* Up limit of concurrency workers */
40 int limit_active;
41
42 /* Current number of concurrency workers */
43 int current_active;
44
45 /* Threshold to change current_active */
46 int thresh;
47 unsigned int count;
48 spinlock_t thres_lock;
49};
50
51struct btrfs_workqueue {
52 struct __btrfs_workqueue *normal;
53 struct __btrfs_workqueue *high;
54};
55
56static void normal_work_helper(struct btrfs_work *work);
57
58#define BTRFS_WORK_HELPER(name) \
59noinline_for_stack void btrfs_##name(struct work_struct *arg) \
60{ \
61 struct btrfs_work *work = container_of(arg, struct btrfs_work, \
62 normal_work); \
63 normal_work_helper(work); \
64}
65
66struct btrfs_fs_info *
67btrfs_workqueue_owner(const struct __btrfs_workqueue *wq)
68{
69 return wq->fs_info;
70}
71
72struct btrfs_fs_info *
73btrfs_work_owner(const struct btrfs_work *work)
74{
75 return work->wq->fs_info;
76}
77
78bool btrfs_workqueue_normal_congested(const struct btrfs_workqueue *wq)
79{
80 /*
81 * We could compare wq->normal->pending with num_online_cpus()
82 * to support "thresh == NO_THRESHOLD" case, but it requires
83 * moving up atomic_inc/dec in thresh_queue/exec_hook. Let's
84 * postpone it until someone needs the support of that case.
85 */
86 if (wq->normal->thresh == NO_THRESHOLD)
87 return false;
88
89 return atomic_read(&wq->normal->pending) > wq->normal->thresh * 2;
90}
91
92BTRFS_WORK_HELPER(worker_helper);
93BTRFS_WORK_HELPER(delalloc_helper);
94BTRFS_WORK_HELPER(flush_delalloc_helper);
95BTRFS_WORK_HELPER(cache_helper);
96BTRFS_WORK_HELPER(submit_helper);
97BTRFS_WORK_HELPER(fixup_helper);
98BTRFS_WORK_HELPER(endio_helper);
99BTRFS_WORK_HELPER(endio_meta_helper);
100BTRFS_WORK_HELPER(endio_meta_write_helper);
101BTRFS_WORK_HELPER(endio_raid56_helper);
102BTRFS_WORK_HELPER(endio_repair_helper);
103BTRFS_WORK_HELPER(rmw_helper);
104BTRFS_WORK_HELPER(endio_write_helper);
105BTRFS_WORK_HELPER(freespace_write_helper);
106BTRFS_WORK_HELPER(delayed_meta_helper);
107BTRFS_WORK_HELPER(readahead_helper);
108BTRFS_WORK_HELPER(qgroup_rescan_helper);
109BTRFS_WORK_HELPER(extent_refs_helper);
110BTRFS_WORK_HELPER(scrub_helper);
111BTRFS_WORK_HELPER(scrubwrc_helper);
112BTRFS_WORK_HELPER(scrubnc_helper);
113BTRFS_WORK_HELPER(scrubparity_helper);
114
115static struct __btrfs_workqueue *
116__btrfs_alloc_workqueue(struct btrfs_fs_info *fs_info, const char *name,
117 unsigned int flags, int limit_active, int thresh)
118{
119 struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_KERNEL);
120
121 if (!ret)
122 return NULL;
123
124 ret->fs_info = fs_info;
125 ret->limit_active = limit_active;
126 atomic_set(&ret->pending, 0);
127 if (thresh == 0)
128 thresh = DFT_THRESHOLD;
129 /* For low threshold, disabling threshold is a better choice */
130 if (thresh < DFT_THRESHOLD) {
131 ret->current_active = limit_active;
132 ret->thresh = NO_THRESHOLD;
133 } else {
134 /*
135 * For threshold-able wq, let its concurrency grow on demand.
136 * Use minimal max_active at alloc time to reduce resource
137 * usage.
138 */
139 ret->current_active = 1;
140 ret->thresh = thresh;
141 }
142
143 if (flags & WQ_HIGHPRI)
144 ret->normal_wq = alloc_workqueue("btrfs-%s-high", flags,
145 ret->current_active, name);
146 else
147 ret->normal_wq = alloc_workqueue("btrfs-%s", flags,
148 ret->current_active, name);
149 if (!ret->normal_wq) {
150 kfree(ret);
151 return NULL;
152 }
153
154 INIT_LIST_HEAD(&ret->ordered_list);
155 spin_lock_init(&ret->list_lock);
156 spin_lock_init(&ret->thres_lock);
157 trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
158 return ret;
159}
160
161static inline void
162__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
163
164struct btrfs_workqueue *btrfs_alloc_workqueue(struct btrfs_fs_info *fs_info,
165 const char *name,
166 unsigned int flags,
167 int limit_active,
168 int thresh)
169{
170 struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_KERNEL);
171
172 if (!ret)
173 return NULL;
174
175 ret->normal = __btrfs_alloc_workqueue(fs_info, name,
176 flags & ~WQ_HIGHPRI,
177 limit_active, thresh);
178 if (!ret->normal) {
179 kfree(ret);
180 return NULL;
181 }
182
183 if (flags & WQ_HIGHPRI) {
184 ret->high = __btrfs_alloc_workqueue(fs_info, name, flags,
185 limit_active, thresh);
186 if (!ret->high) {
187 __btrfs_destroy_workqueue(ret->normal);
188 kfree(ret);
189 return NULL;
190 }
191 }
192 return ret;
193}
194
195/*
196 * Hook for threshold which will be called in btrfs_queue_work.
197 * This hook WILL be called in IRQ handler context,
198 * so workqueue_set_max_active MUST NOT be called in this hook
199 */
200static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
201{
202 if (wq->thresh == NO_THRESHOLD)
203 return;
204 atomic_inc(&wq->pending);
205}
206
207/*
208 * Hook for threshold which will be called before executing the work,
209 * This hook is called in kthread content.
210 * So workqueue_set_max_active is called here.
211 */
212static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
213{
214 int new_current_active;
215 long pending;
216 int need_change = 0;
217
218 if (wq->thresh == NO_THRESHOLD)
219 return;
220
221 atomic_dec(&wq->pending);
222 spin_lock(&wq->thres_lock);
223 /*
224 * Use wq->count to limit the calling frequency of
225 * workqueue_set_max_active.
226 */
227 wq->count++;
228 wq->count %= (wq->thresh / 4);
229 if (!wq->count)
230 goto out;
231 new_current_active = wq->current_active;
232
233 /*
234 * pending may be changed later, but it's OK since we really
235 * don't need it so accurate to calculate new_max_active.
236 */
237 pending = atomic_read(&wq->pending);
238 if (pending > wq->thresh)
239 new_current_active++;
240 if (pending < wq->thresh / 2)
241 new_current_active--;
242 new_current_active = clamp_val(new_current_active, 1, wq->limit_active);
243 if (new_current_active != wq->current_active) {
244 need_change = 1;
245 wq->current_active = new_current_active;
246 }
247out:
248 spin_unlock(&wq->thres_lock);
249
250 if (need_change) {
251 workqueue_set_max_active(wq->normal_wq, wq->current_active);
252 }
253}
254
255static void run_ordered_work(struct __btrfs_workqueue *wq)
256{
257 struct list_head *list = &wq->ordered_list;
258 struct btrfs_work *work;
259 spinlock_t *lock = &wq->list_lock;
260 unsigned long flags;
261
262 while (1) {
263 void *wtag;
264
265 spin_lock_irqsave(lock, flags);
266 if (list_empty(list))
267 break;
268 work = list_entry(list->next, struct btrfs_work,
269 ordered_list);
270 if (!test_bit(WORK_DONE_BIT, &work->flags))
271 break;
272
273 /*
274 * we are going to call the ordered done function, but
275 * we leave the work item on the list as a barrier so
276 * that later work items that are done don't have their
277 * functions called before this one returns
278 */
279 if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
280 break;
281 trace_btrfs_ordered_sched(work);
282 spin_unlock_irqrestore(lock, flags);
283 work->ordered_func(work);
284
285 /* now take the lock again and drop our item from the list */
286 spin_lock_irqsave(lock, flags);
287 list_del(&work->ordered_list);
288 spin_unlock_irqrestore(lock, flags);
289
290 /*
291 * We don't want to call the ordered free functions with the
292 * lock held though. Save the work as tag for the trace event,
293 * because the callback could free the structure.
294 */
295 wtag = work;
296 work->ordered_free(work);
297 trace_btrfs_all_work_done(wq->fs_info, wtag);
298 }
299 spin_unlock_irqrestore(lock, flags);
300}
301
302static void normal_work_helper(struct btrfs_work *work)
303{
304 struct __btrfs_workqueue *wq;
305 void *wtag;
306 int need_order = 0;
307
308 /*
309 * We should not touch things inside work in the following cases:
310 * 1) after work->func() if it has no ordered_free
311 * Since the struct is freed in work->func().
312 * 2) after setting WORK_DONE_BIT
313 * The work may be freed in other threads almost instantly.
314 * So we save the needed things here.
315 */
316 if (work->ordered_func)
317 need_order = 1;
318 wq = work->wq;
319 /* Safe for tracepoints in case work gets freed by the callback */
320 wtag = work;
321
322 trace_btrfs_work_sched(work);
323 thresh_exec_hook(wq);
324 work->func(work);
325 if (need_order) {
326 set_bit(WORK_DONE_BIT, &work->flags);
327 run_ordered_work(wq);
328 }
329 if (!need_order)
330 trace_btrfs_all_work_done(wq->fs_info, wtag);
331}
332
333void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t uniq_func,
334 btrfs_func_t func,
335 btrfs_func_t ordered_func,
336 btrfs_func_t ordered_free)
337{
338 work->func = func;
339 work->ordered_func = ordered_func;
340 work->ordered_free = ordered_free;
341 INIT_WORK(&work->normal_work, uniq_func);
342 INIT_LIST_HEAD(&work->ordered_list);
343 work->flags = 0;
344}
345
346static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
347 struct btrfs_work *work)
348{
349 unsigned long flags;
350
351 work->wq = wq;
352 thresh_queue_hook(wq);
353 if (work->ordered_func) {
354 spin_lock_irqsave(&wq->list_lock, flags);
355 list_add_tail(&work->ordered_list, &wq->ordered_list);
356 spin_unlock_irqrestore(&wq->list_lock, flags);
357 }
358 trace_btrfs_work_queued(work);
359 queue_work(wq->normal_wq, &work->normal_work);
360}
361
362void btrfs_queue_work(struct btrfs_workqueue *wq,
363 struct btrfs_work *work)
364{
365 struct __btrfs_workqueue *dest_wq;
366
367 if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
368 dest_wq = wq->high;
369 else
370 dest_wq = wq->normal;
371 __btrfs_queue_work(dest_wq, work);
372}
373
374static inline void
375__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
376{
377 destroy_workqueue(wq->normal_wq);
378 trace_btrfs_workqueue_destroy(wq);
379 kfree(wq);
380}
381
382void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
383{
384 if (!wq)
385 return;
386 if (wq->high)
387 __btrfs_destroy_workqueue(wq->high);
388 __btrfs_destroy_workqueue(wq->normal);
389 kfree(wq);
390}
391
392void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int limit_active)
393{
394 if (!wq)
395 return;
396 wq->normal->limit_active = limit_active;
397 if (wq->high)
398 wq->high->limit_active = limit_active;
399}
400
401void btrfs_set_work_high_priority(struct btrfs_work *work)
402{
403 set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
404}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007 Oracle. All rights reserved.
4 * Copyright (C) 2014 Fujitsu. All rights reserved.
5 */
6
7#include <linux/kthread.h>
8#include <linux/slab.h>
9#include <linux/list.h>
10#include <linux/spinlock.h>
11#include <linux/freezer.h>
12#include "async-thread.h"
13#include "ctree.h"
14
15enum {
16 WORK_DONE_BIT,
17 WORK_ORDER_DONE_BIT,
18};
19
20#define NO_THRESHOLD (-1)
21#define DFT_THRESHOLD (32)
22
23struct btrfs_workqueue {
24 struct workqueue_struct *normal_wq;
25
26 /* File system this workqueue services */
27 struct btrfs_fs_info *fs_info;
28
29 /* List head pointing to ordered work list */
30 struct list_head ordered_list;
31
32 /* Spinlock for ordered_list */
33 spinlock_t list_lock;
34
35 /* Thresholding related variants */
36 atomic_t pending;
37
38 /* Up limit of concurrency workers */
39 int limit_active;
40
41 /* Current number of concurrency workers */
42 int current_active;
43
44 /* Threshold to change current_active */
45 int thresh;
46 unsigned int count;
47 spinlock_t thres_lock;
48};
49
50struct btrfs_fs_info * __pure btrfs_workqueue_owner(const struct btrfs_workqueue *wq)
51{
52 return wq->fs_info;
53}
54
55struct btrfs_fs_info * __pure btrfs_work_owner(const struct btrfs_work *work)
56{
57 return work->wq->fs_info;
58}
59
60bool btrfs_workqueue_normal_congested(const struct btrfs_workqueue *wq)
61{
62 /*
63 * We could compare wq->pending with num_online_cpus()
64 * to support "thresh == NO_THRESHOLD" case, but it requires
65 * moving up atomic_inc/dec in thresh_queue/exec_hook. Let's
66 * postpone it until someone needs the support of that case.
67 */
68 if (wq->thresh == NO_THRESHOLD)
69 return false;
70
71 return atomic_read(&wq->pending) > wq->thresh * 2;
72}
73
74struct btrfs_workqueue *btrfs_alloc_workqueue(struct btrfs_fs_info *fs_info,
75 const char *name, unsigned int flags,
76 int limit_active, int thresh)
77{
78 struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_KERNEL);
79
80 if (!ret)
81 return NULL;
82
83 ret->fs_info = fs_info;
84 ret->limit_active = limit_active;
85 atomic_set(&ret->pending, 0);
86 if (thresh == 0)
87 thresh = DFT_THRESHOLD;
88 /* For low threshold, disabling threshold is a better choice */
89 if (thresh < DFT_THRESHOLD) {
90 ret->current_active = limit_active;
91 ret->thresh = NO_THRESHOLD;
92 } else {
93 /*
94 * For threshold-able wq, let its concurrency grow on demand.
95 * Use minimal max_active at alloc time to reduce resource
96 * usage.
97 */
98 ret->current_active = 1;
99 ret->thresh = thresh;
100 }
101
102 ret->normal_wq = alloc_workqueue("btrfs-%s", flags, ret->current_active,
103 name);
104 if (!ret->normal_wq) {
105 kfree(ret);
106 return NULL;
107 }
108
109 INIT_LIST_HEAD(&ret->ordered_list);
110 spin_lock_init(&ret->list_lock);
111 spin_lock_init(&ret->thres_lock);
112 trace_btrfs_workqueue_alloc(ret, name);
113 return ret;
114}
115
116/*
117 * Hook for threshold which will be called in btrfs_queue_work.
118 * This hook WILL be called in IRQ handler context,
119 * so workqueue_set_max_active MUST NOT be called in this hook
120 */
121static inline void thresh_queue_hook(struct btrfs_workqueue *wq)
122{
123 if (wq->thresh == NO_THRESHOLD)
124 return;
125 atomic_inc(&wq->pending);
126}
127
128/*
129 * Hook for threshold which will be called before executing the work,
130 * This hook is called in kthread content.
131 * So workqueue_set_max_active is called here.
132 */
133static inline void thresh_exec_hook(struct btrfs_workqueue *wq)
134{
135 int new_current_active;
136 long pending;
137 int need_change = 0;
138
139 if (wq->thresh == NO_THRESHOLD)
140 return;
141
142 atomic_dec(&wq->pending);
143 spin_lock(&wq->thres_lock);
144 /*
145 * Use wq->count to limit the calling frequency of
146 * workqueue_set_max_active.
147 */
148 wq->count++;
149 wq->count %= (wq->thresh / 4);
150 if (!wq->count)
151 goto out;
152 new_current_active = wq->current_active;
153
154 /*
155 * pending may be changed later, but it's OK since we really
156 * don't need it so accurate to calculate new_max_active.
157 */
158 pending = atomic_read(&wq->pending);
159 if (pending > wq->thresh)
160 new_current_active++;
161 if (pending < wq->thresh / 2)
162 new_current_active--;
163 new_current_active = clamp_val(new_current_active, 1, wq->limit_active);
164 if (new_current_active != wq->current_active) {
165 need_change = 1;
166 wq->current_active = new_current_active;
167 }
168out:
169 spin_unlock(&wq->thres_lock);
170
171 if (need_change) {
172 workqueue_set_max_active(wq->normal_wq, wq->current_active);
173 }
174}
175
176static void run_ordered_work(struct btrfs_workqueue *wq,
177 struct btrfs_work *self)
178{
179 struct list_head *list = &wq->ordered_list;
180 struct btrfs_work *work;
181 spinlock_t *lock = &wq->list_lock;
182 unsigned long flags;
183 bool free_self = false;
184
185 while (1) {
186 spin_lock_irqsave(lock, flags);
187 if (list_empty(list))
188 break;
189 work = list_entry(list->next, struct btrfs_work,
190 ordered_list);
191 if (!test_bit(WORK_DONE_BIT, &work->flags))
192 break;
193 /*
194 * Orders all subsequent loads after reading WORK_DONE_BIT,
195 * paired with the smp_mb__before_atomic in btrfs_work_helper
196 * this guarantees that the ordered function will see all
197 * updates from ordinary work function.
198 */
199 smp_rmb();
200
201 /*
202 * we are going to call the ordered done function, but
203 * we leave the work item on the list as a barrier so
204 * that later work items that are done don't have their
205 * functions called before this one returns
206 */
207 if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
208 break;
209 trace_btrfs_ordered_sched(work);
210 spin_unlock_irqrestore(lock, flags);
211 work->ordered_func(work);
212
213 /* now take the lock again and drop our item from the list */
214 spin_lock_irqsave(lock, flags);
215 list_del(&work->ordered_list);
216 spin_unlock_irqrestore(lock, flags);
217
218 if (work == self) {
219 /*
220 * This is the work item that the worker is currently
221 * executing.
222 *
223 * The kernel workqueue code guarantees non-reentrancy
224 * of work items. I.e., if a work item with the same
225 * address and work function is queued twice, the second
226 * execution is blocked until the first one finishes. A
227 * work item may be freed and recycled with the same
228 * work function; the workqueue code assumes that the
229 * original work item cannot depend on the recycled work
230 * item in that case (see find_worker_executing_work()).
231 *
232 * Note that different types of Btrfs work can depend on
233 * each other, and one type of work on one Btrfs
234 * filesystem may even depend on the same type of work
235 * on another Btrfs filesystem via, e.g., a loop device.
236 * Therefore, we must not allow the current work item to
237 * be recycled until we are really done, otherwise we
238 * break the above assumption and can deadlock.
239 */
240 free_self = true;
241 } else {
242 /*
243 * We don't want to call the ordered free functions with
244 * the lock held.
245 */
246 work->ordered_free(work);
247 /* NB: work must not be dereferenced past this point. */
248 trace_btrfs_all_work_done(wq->fs_info, work);
249 }
250 }
251 spin_unlock_irqrestore(lock, flags);
252
253 if (free_self) {
254 self->ordered_free(self);
255 /* NB: self must not be dereferenced past this point. */
256 trace_btrfs_all_work_done(wq->fs_info, self);
257 }
258}
259
260static void btrfs_work_helper(struct work_struct *normal_work)
261{
262 struct btrfs_work *work = container_of(normal_work, struct btrfs_work,
263 normal_work);
264 struct btrfs_workqueue *wq = work->wq;
265 int need_order = 0;
266
267 /*
268 * We should not touch things inside work in the following cases:
269 * 1) after work->func() if it has no ordered_free
270 * Since the struct is freed in work->func().
271 * 2) after setting WORK_DONE_BIT
272 * The work may be freed in other threads almost instantly.
273 * So we save the needed things here.
274 */
275 if (work->ordered_func)
276 need_order = 1;
277
278 trace_btrfs_work_sched(work);
279 thresh_exec_hook(wq);
280 work->func(work);
281 if (need_order) {
282 /*
283 * Ensures all memory accesses done in the work function are
284 * ordered before setting the WORK_DONE_BIT. Ensuring the thread
285 * which is going to executed the ordered work sees them.
286 * Pairs with the smp_rmb in run_ordered_work.
287 */
288 smp_mb__before_atomic();
289 set_bit(WORK_DONE_BIT, &work->flags);
290 run_ordered_work(wq, work);
291 } else {
292 /* NB: work must not be dereferenced past this point. */
293 trace_btrfs_all_work_done(wq->fs_info, work);
294 }
295}
296
297void btrfs_init_work(struct btrfs_work *work, btrfs_func_t func,
298 btrfs_func_t ordered_func, btrfs_func_t ordered_free)
299{
300 work->func = func;
301 work->ordered_func = ordered_func;
302 work->ordered_free = ordered_free;
303 INIT_WORK(&work->normal_work, btrfs_work_helper);
304 INIT_LIST_HEAD(&work->ordered_list);
305 work->flags = 0;
306}
307
308void btrfs_queue_work(struct btrfs_workqueue *wq, struct btrfs_work *work)
309{
310 unsigned long flags;
311
312 work->wq = wq;
313 thresh_queue_hook(wq);
314 if (work->ordered_func) {
315 spin_lock_irqsave(&wq->list_lock, flags);
316 list_add_tail(&work->ordered_list, &wq->ordered_list);
317 spin_unlock_irqrestore(&wq->list_lock, flags);
318 }
319 trace_btrfs_work_queued(work);
320 queue_work(wq->normal_wq, &work->normal_work);
321}
322
323void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
324{
325 if (!wq)
326 return;
327 destroy_workqueue(wq->normal_wq);
328 trace_btrfs_workqueue_destroy(wq);
329 kfree(wq);
330}
331
332void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int limit_active)
333{
334 if (wq)
335 wq->limit_active = limit_active;
336}
337
338void btrfs_flush_workqueue(struct btrfs_workqueue *wq)
339{
340 flush_workqueue(wq->normal_wq);
341}