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c1d7c514 | 1 | // SPDX-License-Identifier: GPL-2.0 |
8b712842 CM |
2 | /* |
3 | * Copyright (C) 2007 Oracle. All rights reserved. | |
08a9ff32 | 4 | * Copyright (C) 2014 Fujitsu. All rights reserved. |
8b712842 CM |
5 | */ |
6 | ||
7 | #include <linux/kthread.h> | |
5a0e3ad6 | 8 | #include <linux/slab.h> |
8b712842 CM |
9 | #include <linux/list.h> |
10 | #include <linux/spinlock.h> | |
b51912c9 | 11 | #include <linux/freezer.h> |
8b712842 | 12 | #include "async-thread.h" |
52483bc2 | 13 | #include "ctree.h" |
8b712842 | 14 | |
f64ce7b8 DS |
15 | enum { |
16 | WORK_DONE_BIT, | |
17 | WORK_ORDER_DONE_BIT, | |
f64ce7b8 | 18 | }; |
4a69a410 | 19 | |
0bd9289c QW |
20 | #define NO_THRESHOLD (-1) |
21 | #define DFT_THRESHOLD (32) | |
22 | ||
a31b4a43 | 23 | struct btrfs_workqueue { |
08a9ff32 | 24 | struct workqueue_struct *normal_wq; |
cb001095 JM |
25 | |
26 | /* File system this workqueue services */ | |
27 | struct btrfs_fs_info *fs_info; | |
28 | ||
08a9ff32 QW |
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; | |
0bd9289c QW |
34 | |
35 | /* Thresholding related variants */ | |
36 | atomic_t pending; | |
c6dd6ea5 QW |
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 */ | |
0bd9289c QW |
45 | int thresh; |
46 | unsigned int count; | |
47 | spinlock_t thres_lock; | |
08a9ff32 QW |
48 | }; |
49 | ||
a31b4a43 | 50 | struct btrfs_fs_info * __pure btrfs_workqueue_owner(const struct btrfs_workqueue *wq) |
cb001095 JM |
51 | { |
52 | return wq->fs_info; | |
53 | } | |
54 | ||
e1f60a65 | 55 | struct btrfs_fs_info * __pure btrfs_work_owner(const struct btrfs_work *work) |
cb001095 JM |
56 | { |
57 | return work->wq->fs_info; | |
58 | } | |
59 | ||
9a35b637 | 60 | bool btrfs_workqueue_normal_congested(const struct btrfs_workqueue *wq) |
2939e1a8 MP |
61 | { |
62 | /* | |
a31b4a43 | 63 | * We could compare wq->pending with num_online_cpus() |
2939e1a8 MP |
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 | */ | |
a31b4a43 | 68 | if (wq->thresh == NO_THRESHOLD) |
2939e1a8 MP |
69 | return false; |
70 | ||
a31b4a43 | 71 | return atomic_read(&wq->pending) > wq->thresh * 2; |
2939e1a8 MP |
72 | } |
73 | ||
58e814fc TH |
74 | static void btrfs_init_workqueue(struct btrfs_workqueue *wq, |
75 | struct btrfs_fs_info *fs_info) | |
76 | { | |
77 | wq->fs_info = fs_info; | |
78 | atomic_set(&wq->pending, 0); | |
79 | INIT_LIST_HEAD(&wq->ordered_list); | |
80 | spin_lock_init(&wq->list_lock); | |
81 | spin_lock_init(&wq->thres_lock); | |
82 | } | |
83 | ||
a31b4a43 CH |
84 | struct btrfs_workqueue *btrfs_alloc_workqueue(struct btrfs_fs_info *fs_info, |
85 | const char *name, unsigned int flags, | |
86 | int limit_active, int thresh) | |
1ca08976 | 87 | { |
a31b4a43 | 88 | struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_KERNEL); |
1ca08976 | 89 | |
5d99a998 | 90 | if (!ret) |
1ca08976 QW |
91 | return NULL; |
92 | ||
58e814fc TH |
93 | btrfs_init_workqueue(ret, fs_info); |
94 | ||
c6dd6ea5 | 95 | ret->limit_active = limit_active; |
0bd9289c QW |
96 | if (thresh == 0) |
97 | thresh = DFT_THRESHOLD; | |
98 | /* For low threshold, disabling threshold is a better choice */ | |
99 | if (thresh < DFT_THRESHOLD) { | |
c6dd6ea5 | 100 | ret->current_active = limit_active; |
0bd9289c QW |
101 | ret->thresh = NO_THRESHOLD; |
102 | } else { | |
c6dd6ea5 QW |
103 | /* |
104 | * For threshold-able wq, let its concurrency grow on demand. | |
105 | * Use minimal max_active at alloc time to reduce resource | |
106 | * usage. | |
107 | */ | |
108 | ret->current_active = 1; | |
0bd9289c QW |
109 | ret->thresh = thresh; |
110 | } | |
111 | ||
a31b4a43 CH |
112 | ret->normal_wq = alloc_workqueue("btrfs-%s", flags, ret->current_active, |
113 | name); | |
5d99a998 | 114 | if (!ret->normal_wq) { |
1ca08976 QW |
115 | kfree(ret); |
116 | return NULL; | |
117 | } | |
118 | ||
58e814fc TH |
119 | trace_btrfs_workqueue_alloc(ret, name); |
120 | return ret; | |
121 | } | |
122 | ||
123 | struct btrfs_workqueue *btrfs_alloc_ordered_workqueue( | |
124 | struct btrfs_fs_info *fs_info, const char *name, | |
125 | unsigned int flags) | |
126 | { | |
127 | struct btrfs_workqueue *ret; | |
128 | ||
129 | ret = kzalloc(sizeof(*ret), GFP_KERNEL); | |
130 | if (!ret) | |
131 | return NULL; | |
132 | ||
133 | btrfs_init_workqueue(ret, fs_info); | |
134 | ||
135 | /* Ordered workqueues don't allow @max_active adjustments. */ | |
136 | ret->limit_active = 1; | |
137 | ret->current_active = 1; | |
138 | ret->thresh = NO_THRESHOLD; | |
139 | ||
140 | ret->normal_wq = alloc_ordered_workqueue("btrfs-%s", flags, name); | |
141 | if (!ret->normal_wq) { | |
142 | kfree(ret); | |
143 | return NULL; | |
144 | } | |
145 | ||
a31b4a43 | 146 | trace_btrfs_workqueue_alloc(ret, name); |
08a9ff32 QW |
147 | return ret; |
148 | } | |
149 | ||
0bd9289c QW |
150 | /* |
151 | * Hook for threshold which will be called in btrfs_queue_work. | |
152 | * This hook WILL be called in IRQ handler context, | |
153 | * so workqueue_set_max_active MUST NOT be called in this hook | |
154 | */ | |
a31b4a43 | 155 | static inline void thresh_queue_hook(struct btrfs_workqueue *wq) |
0bd9289c QW |
156 | { |
157 | if (wq->thresh == NO_THRESHOLD) | |
158 | return; | |
159 | atomic_inc(&wq->pending); | |
160 | } | |
161 | ||
162 | /* | |
163 | * Hook for threshold which will be called before executing the work, | |
164 | * This hook is called in kthread content. | |
165 | * So workqueue_set_max_active is called here. | |
166 | */ | |
a31b4a43 | 167 | static inline void thresh_exec_hook(struct btrfs_workqueue *wq) |
0bd9289c | 168 | { |
c6dd6ea5 | 169 | int new_current_active; |
0bd9289c QW |
170 | long pending; |
171 | int need_change = 0; | |
172 | ||
173 | if (wq->thresh == NO_THRESHOLD) | |
174 | return; | |
175 | ||
176 | atomic_dec(&wq->pending); | |
177 | spin_lock(&wq->thres_lock); | |
178 | /* | |
179 | * Use wq->count to limit the calling frequency of | |
180 | * workqueue_set_max_active. | |
181 | */ | |
182 | wq->count++; | |
183 | wq->count %= (wq->thresh / 4); | |
184 | if (!wq->count) | |
185 | goto out; | |
c6dd6ea5 | 186 | new_current_active = wq->current_active; |
0bd9289c QW |
187 | |
188 | /* | |
189 | * pending may be changed later, but it's OK since we really | |
190 | * don't need it so accurate to calculate new_max_active. | |
191 | */ | |
192 | pending = atomic_read(&wq->pending); | |
193 | if (pending > wq->thresh) | |
c6dd6ea5 | 194 | new_current_active++; |
0bd9289c | 195 | if (pending < wq->thresh / 2) |
c6dd6ea5 QW |
196 | new_current_active--; |
197 | new_current_active = clamp_val(new_current_active, 1, wq->limit_active); | |
198 | if (new_current_active != wq->current_active) { | |
0bd9289c | 199 | need_change = 1; |
c6dd6ea5 | 200 | wq->current_active = new_current_active; |
0bd9289c QW |
201 | } |
202 | out: | |
203 | spin_unlock(&wq->thres_lock); | |
204 | ||
205 | if (need_change) { | |
c6dd6ea5 | 206 | workqueue_set_max_active(wq->normal_wq, wq->current_active); |
0bd9289c QW |
207 | } |
208 | } | |
209 | ||
a31b4a43 | 210 | static void run_ordered_work(struct btrfs_workqueue *wq, |
c495dcd6 | 211 | struct btrfs_work *self) |
08a9ff32 QW |
212 | { |
213 | struct list_head *list = &wq->ordered_list; | |
d458b054 | 214 | struct btrfs_work *work; |
08a9ff32 QW |
215 | spinlock_t *lock = &wq->list_lock; |
216 | unsigned long flags; | |
c495dcd6 | 217 | bool free_self = false; |
08a9ff32 QW |
218 | |
219 | while (1) { | |
220 | spin_lock_irqsave(lock, flags); | |
221 | if (list_empty(list)) | |
222 | break; | |
d458b054 | 223 | work = list_entry(list->next, struct btrfs_work, |
08a9ff32 QW |
224 | ordered_list); |
225 | if (!test_bit(WORK_DONE_BIT, &work->flags)) | |
226 | break; | |
45da9c17 NB |
227 | /* |
228 | * Orders all subsequent loads after reading WORK_DONE_BIT, | |
229 | * paired with the smp_mb__before_atomic in btrfs_work_helper | |
230 | * this guarantees that the ordered function will see all | |
231 | * updates from ordinary work function. | |
232 | */ | |
233 | smp_rmb(); | |
08a9ff32 QW |
234 | |
235 | /* | |
236 | * we are going to call the ordered done function, but | |
237 | * we leave the work item on the list as a barrier so | |
238 | * that later work items that are done don't have their | |
239 | * functions called before this one returns | |
240 | */ | |
241 | if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags)) | |
242 | break; | |
52483bc2 | 243 | trace_btrfs_ordered_sched(work); |
08a9ff32 QW |
244 | spin_unlock_irqrestore(lock, flags); |
245 | work->ordered_func(work); | |
246 | ||
247 | /* now take the lock again and drop our item from the list */ | |
248 | spin_lock_irqsave(lock, flags); | |
249 | list_del(&work->ordered_list); | |
250 | spin_unlock_irqrestore(lock, flags); | |
251 | ||
c495dcd6 OS |
252 | if (work == self) { |
253 | /* | |
254 | * This is the work item that the worker is currently | |
255 | * executing. | |
256 | * | |
257 | * The kernel workqueue code guarantees non-reentrancy | |
258 | * of work items. I.e., if a work item with the same | |
259 | * address and work function is queued twice, the second | |
260 | * execution is blocked until the first one finishes. A | |
261 | * work item may be freed and recycled with the same | |
262 | * work function; the workqueue code assumes that the | |
263 | * original work item cannot depend on the recycled work | |
264 | * item in that case (see find_worker_executing_work()). | |
265 | * | |
a0cac0ec OS |
266 | * Note that different types of Btrfs work can depend on |
267 | * each other, and one type of work on one Btrfs | |
268 | * filesystem may even depend on the same type of work | |
269 | * on another Btrfs filesystem via, e.g., a loop device. | |
270 | * Therefore, we must not allow the current work item to | |
271 | * be recycled until we are really done, otherwise we | |
272 | * break the above assumption and can deadlock. | |
c495dcd6 OS |
273 | */ |
274 | free_self = true; | |
275 | } else { | |
276 | /* | |
277 | * We don't want to call the ordered free functions with | |
c9eb55db | 278 | * the lock held. |
c495dcd6 | 279 | */ |
c495dcd6 | 280 | work->ordered_free(work); |
c9eb55db OS |
281 | /* NB: work must not be dereferenced past this point. */ |
282 | trace_btrfs_all_work_done(wq->fs_info, work); | |
c495dcd6 | 283 | } |
08a9ff32 QW |
284 | } |
285 | spin_unlock_irqrestore(lock, flags); | |
c495dcd6 OS |
286 | |
287 | if (free_self) { | |
c495dcd6 | 288 | self->ordered_free(self); |
c9eb55db OS |
289 | /* NB: self must not be dereferenced past this point. */ |
290 | trace_btrfs_all_work_done(wq->fs_info, self); | |
c495dcd6 | 291 | } |
08a9ff32 QW |
292 | } |
293 | ||
a0cac0ec | 294 | static void btrfs_work_helper(struct work_struct *normal_work) |
08a9ff32 | 295 | { |
a0cac0ec OS |
296 | struct btrfs_work *work = container_of(normal_work, struct btrfs_work, |
297 | normal_work); | |
a31b4a43 | 298 | struct btrfs_workqueue *wq = work->wq; |
08a9ff32 QW |
299 | int need_order = 0; |
300 | ||
08a9ff32 QW |
301 | /* |
302 | * We should not touch things inside work in the following cases: | |
303 | * 1) after work->func() if it has no ordered_free | |
304 | * Since the struct is freed in work->func(). | |
305 | * 2) after setting WORK_DONE_BIT | |
306 | * The work may be freed in other threads almost instantly. | |
307 | * So we save the needed things here. | |
308 | */ | |
309 | if (work->ordered_func) | |
310 | need_order = 1; | |
08a9ff32 | 311 | |
52483bc2 | 312 | trace_btrfs_work_sched(work); |
0bd9289c | 313 | thresh_exec_hook(wq); |
08a9ff32 QW |
314 | work->func(work); |
315 | if (need_order) { | |
45da9c17 NB |
316 | /* |
317 | * Ensures all memory accesses done in the work function are | |
318 | * ordered before setting the WORK_DONE_BIT. Ensuring the thread | |
319 | * which is going to executed the ordered work sees them. | |
320 | * Pairs with the smp_rmb in run_ordered_work. | |
321 | */ | |
322 | smp_mb__before_atomic(); | |
08a9ff32 | 323 | set_bit(WORK_DONE_BIT, &work->flags); |
c495dcd6 | 324 | run_ordered_work(wq, work); |
c9eb55db OS |
325 | } else { |
326 | /* NB: work must not be dereferenced past this point. */ | |
327 | trace_btrfs_all_work_done(wq->fs_info, work); | |
08a9ff32 QW |
328 | } |
329 | } | |
330 | ||
a0cac0ec OS |
331 | void btrfs_init_work(struct btrfs_work *work, btrfs_func_t func, |
332 | btrfs_func_t ordered_func, btrfs_func_t ordered_free) | |
08a9ff32 QW |
333 | { |
334 | work->func = func; | |
335 | work->ordered_func = ordered_func; | |
336 | work->ordered_free = ordered_free; | |
a0cac0ec | 337 | INIT_WORK(&work->normal_work, btrfs_work_helper); |
08a9ff32 QW |
338 | INIT_LIST_HEAD(&work->ordered_list); |
339 | work->flags = 0; | |
340 | } | |
341 | ||
a31b4a43 | 342 | void btrfs_queue_work(struct btrfs_workqueue *wq, struct btrfs_work *work) |
08a9ff32 QW |
343 | { |
344 | unsigned long flags; | |
345 | ||
346 | work->wq = wq; | |
0bd9289c | 347 | thresh_queue_hook(wq); |
08a9ff32 QW |
348 | if (work->ordered_func) { |
349 | spin_lock_irqsave(&wq->list_lock, flags); | |
350 | list_add_tail(&work->ordered_list, &wq->ordered_list); | |
351 | spin_unlock_irqrestore(&wq->list_lock, flags); | |
352 | } | |
52483bc2 | 353 | trace_btrfs_work_queued(work); |
0a95b851 | 354 | queue_work(wq->normal_wq, &work->normal_work); |
08a9ff32 QW |
355 | } |
356 | ||
d458b054 | 357 | void btrfs_destroy_workqueue(struct btrfs_workqueue *wq) |
1ca08976 QW |
358 | { |
359 | if (!wq) | |
360 | return; | |
a31b4a43 CH |
361 | destroy_workqueue(wq->normal_wq); |
362 | trace_btrfs_workqueue_destroy(wq); | |
ef66af10 | 363 | kfree(wq); |
1ca08976 QW |
364 | } |
365 | ||
c6dd6ea5 | 366 | void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int limit_active) |
08a9ff32 | 367 | { |
a31b4a43 CH |
368 | if (wq) |
369 | wq->limit_active = limit_active; | |
08a9ff32 | 370 | } |
f0cc2cd7 FM |
371 | |
372 | void btrfs_flush_workqueue(struct btrfs_workqueue *wq) | |
373 | { | |
a31b4a43 | 374 | flush_workqueue(wq->normal_wq); |
f0cc2cd7 | 375 | } |