1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | /* |
3 | * include/linux/writeback.h |
4 | */ |
5 | #ifndef WRITEBACK_H |
6 | #define WRITEBACK_H |
7 | |
8 | #include <linux/sched.h> |
9 | #include <linux/workqueue.h> |
10 | #include <linux/fs.h> |
11 | #include <linux/flex_proportions.h> |
12 | #include <linux/backing-dev-defs.h> |
13 | #include <linux/blk_types.h> |
14 | |
15 | struct bio; |
16 | |
17 | DECLARE_PER_CPU(int, dirty_throttle_leaks); |
18 | |
19 | /* |
20 | * The global dirty threshold is normally equal to the global dirty limit, |
21 | * except when the system suddenly allocates a lot of anonymous memory and |
22 | * knocks down the global dirty threshold quickly, in which case the global |
23 | * dirty limit will follow down slowly to prevent livelocking all dirtier tasks. |
24 | */ |
25 | #define DIRTY_SCOPE 8 |
26 | |
27 | struct backing_dev_info; |
28 | |
29 | /* |
30 | * fs/fs-writeback.c |
31 | */ |
32 | enum writeback_sync_modes { |
33 | WB_SYNC_NONE, /* Don't wait on anything */ |
34 | WB_SYNC_ALL, /* Wait on every mapping */ |
35 | }; |
36 | |
37 | /* |
38 | * A control structure which tells the writeback code what to do. These are |
39 | * always on the stack, and hence need no locking. They are always initialised |
40 | * in a manner such that unspecified fields are set to zero. |
41 | */ |
42 | struct writeback_control { |
43 | long nr_to_write; /* Write this many pages, and decrement |
44 | this for each page written */ |
45 | long pages_skipped; /* Pages which were not written */ |
46 | |
47 | /* |
48 | * For a_ops->writepages(): if start or end are non-zero then this is |
49 | * a hint that the filesystem need only write out the pages inside that |
50 | * byterange. The byte at `end' is included in the writeout request. |
51 | */ |
52 | loff_t range_start; |
53 | loff_t range_end; |
54 | |
55 | enum writeback_sync_modes sync_mode; |
56 | |
57 | unsigned for_kupdate:1; /* A kupdate writeback */ |
58 | unsigned for_background:1; /* A background writeback */ |
59 | unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */ |
60 | unsigned for_reclaim:1; /* Invoked from the page allocator */ |
61 | unsigned range_cyclic:1; /* range_start is cyclic */ |
62 | unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ |
63 | unsigned unpinned_fscache_wb:1; /* Cleared I_PINNING_FSCACHE_WB */ |
64 | |
65 | /* |
66 | * When writeback IOs are bounced through async layers, only the |
67 | * initial synchronous phase should be accounted towards inode |
68 | * cgroup ownership arbitration to avoid confusion. Later stages |
69 | * can set the following flag to disable the accounting. |
70 | */ |
71 | unsigned no_cgroup_owner:1; |
72 | |
73 | /* To enable batching of swap writes to non-block-device backends, |
74 | * "plug" can be set point to a 'struct swap_iocb *'. When all swap |
75 | * writes have been submitted, if with swap_iocb is not NULL, |
76 | * swap_write_unplug() should be called. |
77 | */ |
78 | struct swap_iocb **swap_plug; |
79 | |
80 | #ifdef CONFIG_CGROUP_WRITEBACK |
81 | struct bdi_writeback *wb; /* wb this writeback is issued under */ |
82 | struct inode *inode; /* inode being written out */ |
83 | |
84 | /* foreign inode detection, see wbc_detach_inode() */ |
85 | int wb_id; /* current wb id */ |
86 | int wb_lcand_id; /* last foreign candidate wb id */ |
87 | int wb_tcand_id; /* this foreign candidate wb id */ |
88 | size_t wb_bytes; /* bytes written by current wb */ |
89 | size_t wb_lcand_bytes; /* bytes written by last candidate */ |
90 | size_t wb_tcand_bytes; /* bytes written by this candidate */ |
91 | #endif |
92 | }; |
93 | |
94 | static inline blk_opf_t wbc_to_write_flags(struct writeback_control *wbc) |
95 | { |
96 | blk_opf_t flags = 0; |
97 | |
98 | if (wbc->sync_mode == WB_SYNC_ALL) |
99 | flags |= REQ_SYNC; |
100 | else if (wbc->for_kupdate || wbc->for_background) |
101 | flags |= REQ_BACKGROUND; |
102 | |
103 | return flags; |
104 | } |
105 | |
106 | #ifdef CONFIG_CGROUP_WRITEBACK |
107 | #define wbc_blkcg_css(wbc) \ |
108 | ((wbc)->wb ? (wbc)->wb->blkcg_css : blkcg_root_css) |
109 | #else |
110 | #define wbc_blkcg_css(wbc) (blkcg_root_css) |
111 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
112 | |
113 | /* |
114 | * A wb_domain represents a domain that wb's (bdi_writeback's) belong to |
115 | * and are measured against each other in. There always is one global |
116 | * domain, global_wb_domain, that every wb in the system is a member of. |
117 | * This allows measuring the relative bandwidth of each wb to distribute |
118 | * dirtyable memory accordingly. |
119 | */ |
120 | struct wb_domain { |
121 | spinlock_t lock; |
122 | |
123 | /* |
124 | * Scale the writeback cache size proportional to the relative |
125 | * writeout speed. |
126 | * |
127 | * We do this by keeping a floating proportion between BDIs, based |
128 | * on page writeback completions [end_page_writeback()]. Those |
129 | * devices that write out pages fastest will get the larger share, |
130 | * while the slower will get a smaller share. |
131 | * |
132 | * We use page writeout completions because we are interested in |
133 | * getting rid of dirty pages. Having them written out is the |
134 | * primary goal. |
135 | * |
136 | * We introduce a concept of time, a period over which we measure |
137 | * these events, because demand can/will vary over time. The length |
138 | * of this period itself is measured in page writeback completions. |
139 | */ |
140 | struct fprop_global completions; |
141 | struct timer_list period_timer; /* timer for aging of completions */ |
142 | unsigned long period_time; |
143 | |
144 | /* |
145 | * The dirtyable memory and dirty threshold could be suddenly |
146 | * knocked down by a large amount (eg. on the startup of KVM in a |
147 | * swapless system). This may throw the system into deep dirty |
148 | * exceeded state and throttle heavy/light dirtiers alike. To |
149 | * retain good responsiveness, maintain global_dirty_limit for |
150 | * tracking slowly down to the knocked down dirty threshold. |
151 | * |
152 | * Both fields are protected by ->lock. |
153 | */ |
154 | unsigned long dirty_limit_tstamp; |
155 | unsigned long dirty_limit; |
156 | }; |
157 | |
158 | /** |
159 | * wb_domain_size_changed - memory available to a wb_domain has changed |
160 | * @dom: wb_domain of interest |
161 | * |
162 | * This function should be called when the amount of memory available to |
163 | * @dom has changed. It resets @dom's dirty limit parameters to prevent |
164 | * the past values which don't match the current configuration from skewing |
165 | * dirty throttling. Without this, when memory size of a wb_domain is |
166 | * greatly reduced, the dirty throttling logic may allow too many pages to |
167 | * be dirtied leading to consecutive unnecessary OOMs and may get stuck in |
168 | * that situation. |
169 | */ |
170 | static inline void wb_domain_size_changed(struct wb_domain *dom) |
171 | { |
172 | spin_lock(lock: &dom->lock); |
173 | dom->dirty_limit_tstamp = jiffies; |
174 | dom->dirty_limit = 0; |
175 | spin_unlock(lock: &dom->lock); |
176 | } |
177 | |
178 | /* |
179 | * fs/fs-writeback.c |
180 | */ |
181 | struct bdi_writeback; |
182 | void writeback_inodes_sb(struct super_block *, enum wb_reason reason); |
183 | void writeback_inodes_sb_nr(struct super_block *, unsigned long nr, |
184 | enum wb_reason reason); |
185 | void try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason); |
186 | void sync_inodes_sb(struct super_block *); |
187 | void wakeup_flusher_threads(enum wb_reason reason); |
188 | void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, |
189 | enum wb_reason reason); |
190 | void inode_wait_for_writeback(struct inode *inode); |
191 | void inode_io_list_del(struct inode *inode); |
192 | |
193 | /* writeback.h requires fs.h; it, too, is not included from here. */ |
194 | static inline void wait_on_inode(struct inode *inode) |
195 | { |
196 | might_sleep(); |
197 | wait_on_bit(word: &inode->i_state, __I_NEW, TASK_UNINTERRUPTIBLE); |
198 | } |
199 | |
200 | #ifdef CONFIG_CGROUP_WRITEBACK |
201 | |
202 | #include <linux/cgroup.h> |
203 | #include <linux/bio.h> |
204 | |
205 | void __inode_attach_wb(struct inode *inode, struct folio *folio); |
206 | void wbc_attach_and_unlock_inode(struct writeback_control *wbc, |
207 | struct inode *inode) |
208 | __releases(&inode->i_lock); |
209 | void wbc_detach_inode(struct writeback_control *wbc); |
210 | void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, |
211 | size_t bytes); |
212 | int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, |
213 | enum wb_reason reason, struct wb_completion *done); |
214 | void cgroup_writeback_umount(void); |
215 | bool cleanup_offline_cgwb(struct bdi_writeback *wb); |
216 | |
217 | /** |
218 | * inode_attach_wb - associate an inode with its wb |
219 | * @inode: inode of interest |
220 | * @folio: folio being dirtied (may be NULL) |
221 | * |
222 | * If @inode doesn't have its wb, associate it with the wb matching the |
223 | * memcg of @folio or, if @folio is NULL, %current. May be called w/ or w/o |
224 | * @inode->i_lock. |
225 | */ |
226 | static inline void inode_attach_wb(struct inode *inode, struct folio *folio) |
227 | { |
228 | if (!inode->i_wb) |
229 | __inode_attach_wb(inode, folio); |
230 | } |
231 | |
232 | /** |
233 | * inode_detach_wb - disassociate an inode from its wb |
234 | * @inode: inode of interest |
235 | * |
236 | * @inode is being freed. Detach from its wb. |
237 | */ |
238 | static inline void inode_detach_wb(struct inode *inode) |
239 | { |
240 | if (inode->i_wb) { |
241 | WARN_ON_ONCE(!(inode->i_state & I_CLEAR)); |
242 | wb_put(wb: inode->i_wb); |
243 | inode->i_wb = NULL; |
244 | } |
245 | } |
246 | |
247 | /** |
248 | * wbc_attach_fdatawrite_inode - associate wbc and inode for fdatawrite |
249 | * @wbc: writeback_control of interest |
250 | * @inode: target inode |
251 | * |
252 | * This function is to be used by __filemap_fdatawrite_range(), which is an |
253 | * alternative entry point into writeback code, and first ensures @inode is |
254 | * associated with a bdi_writeback and attaches it to @wbc. |
255 | */ |
256 | static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc, |
257 | struct inode *inode) |
258 | { |
259 | spin_lock(lock: &inode->i_lock); |
260 | inode_attach_wb(inode, NULL); |
261 | wbc_attach_and_unlock_inode(wbc, inode); |
262 | } |
263 | |
264 | /** |
265 | * wbc_init_bio - writeback specific initializtion of bio |
266 | * @wbc: writeback_control for the writeback in progress |
267 | * @bio: bio to be initialized |
268 | * |
269 | * @bio is a part of the writeback in progress controlled by @wbc. Perform |
270 | * writeback specific initialization. This is used to apply the cgroup |
271 | * writeback context. Must be called after the bio has been associated with |
272 | * a device. |
273 | */ |
274 | static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio) |
275 | { |
276 | /* |
277 | * pageout() path doesn't attach @wbc to the inode being written |
278 | * out. This is intentional as we don't want the function to block |
279 | * behind a slow cgroup. Ultimately, we want pageout() to kick off |
280 | * regular writeback instead of writing things out itself. |
281 | */ |
282 | if (wbc->wb) |
283 | bio_associate_blkg_from_css(bio, css: wbc->wb->blkcg_css); |
284 | } |
285 | |
286 | #else /* CONFIG_CGROUP_WRITEBACK */ |
287 | |
288 | static inline void inode_attach_wb(struct inode *inode, struct folio *folio) |
289 | { |
290 | } |
291 | |
292 | static inline void inode_detach_wb(struct inode *inode) |
293 | { |
294 | } |
295 | |
296 | static inline void wbc_attach_and_unlock_inode(struct writeback_control *wbc, |
297 | struct inode *inode) |
298 | __releases(&inode->i_lock) |
299 | { |
300 | spin_unlock(&inode->i_lock); |
301 | } |
302 | |
303 | static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc, |
304 | struct inode *inode) |
305 | { |
306 | } |
307 | |
308 | static inline void wbc_detach_inode(struct writeback_control *wbc) |
309 | { |
310 | } |
311 | |
312 | static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio) |
313 | { |
314 | } |
315 | |
316 | static inline void wbc_account_cgroup_owner(struct writeback_control *wbc, |
317 | struct page *page, size_t bytes) |
318 | { |
319 | } |
320 | |
321 | static inline void cgroup_writeback_umount(void) |
322 | { |
323 | } |
324 | |
325 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
326 | |
327 | /* |
328 | * mm/page-writeback.c |
329 | */ |
330 | void laptop_io_completion(struct backing_dev_info *info); |
331 | void laptop_sync_completion(void); |
332 | void laptop_mode_timer_fn(struct timer_list *t); |
333 | bool node_dirty_ok(struct pglist_data *pgdat); |
334 | int wb_domain_init(struct wb_domain *dom, gfp_t gfp); |
335 | #ifdef CONFIG_CGROUP_WRITEBACK |
336 | void wb_domain_exit(struct wb_domain *dom); |
337 | #endif |
338 | |
339 | extern struct wb_domain global_wb_domain; |
340 | |
341 | /* These are exported to sysctl. */ |
342 | extern unsigned int dirty_writeback_interval; |
343 | extern unsigned int dirty_expire_interval; |
344 | extern unsigned int dirtytime_expire_interval; |
345 | extern int laptop_mode; |
346 | |
347 | int dirtytime_interval_handler(struct ctl_table *table, int write, |
348 | void *buffer, size_t *lenp, loff_t *ppos); |
349 | |
350 | void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); |
351 | unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh); |
352 | |
353 | void wb_update_bandwidth(struct bdi_writeback *wb); |
354 | |
355 | /* Invoke balance dirty pages in async mode. */ |
356 | #define BDP_ASYNC 0x0001 |
357 | |
358 | void balance_dirty_pages_ratelimited(struct address_space *mapping); |
359 | int balance_dirty_pages_ratelimited_flags(struct address_space *mapping, |
360 | unsigned int flags); |
361 | |
362 | bool wb_over_bg_thresh(struct bdi_writeback *wb); |
363 | |
364 | typedef int (*writepage_t)(struct folio *folio, struct writeback_control *wbc, |
365 | void *data); |
366 | |
367 | void tag_pages_for_writeback(struct address_space *mapping, |
368 | pgoff_t start, pgoff_t end); |
369 | int write_cache_pages(struct address_space *mapping, |
370 | struct writeback_control *wbc, writepage_t writepage, |
371 | void *data); |
372 | int do_writepages(struct address_space *mapping, struct writeback_control *wbc); |
373 | void writeback_set_ratelimit(void); |
374 | void tag_pages_for_writeback(struct address_space *mapping, |
375 | pgoff_t start, pgoff_t end); |
376 | |
377 | bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio); |
378 | bool folio_redirty_for_writepage(struct writeback_control *, struct folio *); |
379 | bool redirty_page_for_writepage(struct writeback_control *, struct page *); |
380 | |
381 | void sb_mark_inode_writeback(struct inode *inode); |
382 | void sb_clear_inode_writeback(struct inode *inode); |
383 | |
384 | #endif /* WRITEBACK_H */ |
385 | |