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 | #include <linux/pagevec.h> |
15 | |
16 | struct bio; |
17 | |
18 | DECLARE_PER_CPU(int, dirty_throttle_leaks); |
19 | |
20 | /* |
21 | * The global dirty threshold is normally equal to the global dirty limit, |
22 | * except when the system suddenly allocates a lot of anonymous memory and |
23 | * knocks down the global dirty threshold quickly, in which case the global |
24 | * dirty limit will follow down slowly to prevent livelocking all dirtier tasks. |
25 | */ |
26 | #define DIRTY_SCOPE 8 |
27 | |
28 | struct backing_dev_info; |
29 | |
30 | /* |
31 | * fs/fs-writeback.c |
32 | */ |
33 | enum writeback_sync_modes { |
34 | WB_SYNC_NONE, /* Don't wait on anything */ |
35 | WB_SYNC_ALL, /* Wait on every mapping */ |
36 | }; |
37 | |
38 | /* |
39 | * A control structure which tells the writeback code what to do. These are |
40 | * always on the stack, and hence need no locking. They are always initialised |
41 | * in a manner such that unspecified fields are set to zero. |
42 | */ |
43 | struct writeback_control { |
44 | /* public fields that can be set and/or consumed by the caller: */ |
45 | long nr_to_write; /* Write this many pages, and decrement |
46 | this for each page written */ |
47 | long pages_skipped; /* Pages which were not written */ |
48 | |
49 | /* |
50 | * For a_ops->writepages(): if start or end are non-zero then this is |
51 | * a hint that the filesystem need only write out the pages inside that |
52 | * byterange. The byte at `end' is included in the writeout request. |
53 | */ |
54 | loff_t range_start; |
55 | loff_t range_end; |
56 | |
57 | enum writeback_sync_modes sync_mode; |
58 | |
59 | unsigned for_kupdate:1; /* A kupdate writeback */ |
60 | unsigned for_background:1; /* A background writeback */ |
61 | unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */ |
62 | unsigned for_reclaim:1; /* Invoked from the page allocator */ |
63 | unsigned range_cyclic:1; /* range_start is cyclic */ |
64 | unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ |
65 | unsigned unpinned_netfs_wb:1; /* Cleared I_PINNING_NETFS_WB */ |
66 | |
67 | /* |
68 | * When writeback IOs are bounced through async layers, only the |
69 | * initial synchronous phase should be accounted towards inode |
70 | * cgroup ownership arbitration to avoid confusion. Later stages |
71 | * can set the following flag to disable the accounting. |
72 | */ |
73 | unsigned no_cgroup_owner:1; |
74 | |
75 | /* To enable batching of swap writes to non-block-device backends, |
76 | * "plug" can be set point to a 'struct swap_iocb *'. When all swap |
77 | * writes have been submitted, if with swap_iocb is not NULL, |
78 | * swap_write_unplug() should be called. |
79 | */ |
80 | struct swap_iocb **swap_plug; |
81 | |
82 | /* internal fields used by the ->writepages implementation: */ |
83 | struct folio_batch fbatch; |
84 | pgoff_t index; |
85 | int saved_err; |
86 | |
87 | #ifdef CONFIG_CGROUP_WRITEBACK |
88 | struct bdi_writeback *wb; /* wb this writeback is issued under */ |
89 | struct inode *inode; /* inode being written out */ |
90 | |
91 | /* foreign inode detection, see wbc_detach_inode() */ |
92 | int wb_id; /* current wb id */ |
93 | int wb_lcand_id; /* last foreign candidate wb id */ |
94 | int wb_tcand_id; /* this foreign candidate wb id */ |
95 | size_t wb_bytes; /* bytes written by current wb */ |
96 | size_t wb_lcand_bytes; /* bytes written by last candidate */ |
97 | size_t wb_tcand_bytes; /* bytes written by this candidate */ |
98 | #endif |
99 | }; |
100 | |
101 | static inline blk_opf_t wbc_to_write_flags(struct writeback_control *wbc) |
102 | { |
103 | blk_opf_t flags = 0; |
104 | |
105 | if (wbc->sync_mode == WB_SYNC_ALL) |
106 | flags |= REQ_SYNC; |
107 | else if (wbc->for_kupdate || wbc->for_background) |
108 | flags |= REQ_BACKGROUND; |
109 | |
110 | return flags; |
111 | } |
112 | |
113 | #ifdef CONFIG_CGROUP_WRITEBACK |
114 | #define wbc_blkcg_css(wbc) \ |
115 | ((wbc)->wb ? (wbc)->wb->blkcg_css : blkcg_root_css) |
116 | #else |
117 | #define wbc_blkcg_css(wbc) (blkcg_root_css) |
118 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
119 | |
120 | /* |
121 | * A wb_domain represents a domain that wb's (bdi_writeback's) belong to |
122 | * and are measured against each other in. There always is one global |
123 | * domain, global_wb_domain, that every wb in the system is a member of. |
124 | * This allows measuring the relative bandwidth of each wb to distribute |
125 | * dirtyable memory accordingly. |
126 | */ |
127 | struct wb_domain { |
128 | spinlock_t lock; |
129 | |
130 | /* |
131 | * Scale the writeback cache size proportional to the relative |
132 | * writeout speed. |
133 | * |
134 | * We do this by keeping a floating proportion between BDIs, based |
135 | * on page writeback completions [end_page_writeback()]. Those |
136 | * devices that write out pages fastest will get the larger share, |
137 | * while the slower will get a smaller share. |
138 | * |
139 | * We use page writeout completions because we are interested in |
140 | * getting rid of dirty pages. Having them written out is the |
141 | * primary goal. |
142 | * |
143 | * We introduce a concept of time, a period over which we measure |
144 | * these events, because demand can/will vary over time. The length |
145 | * of this period itself is measured in page writeback completions. |
146 | */ |
147 | struct fprop_global completions; |
148 | struct timer_list period_timer; /* timer for aging of completions */ |
149 | unsigned long period_time; |
150 | |
151 | /* |
152 | * The dirtyable memory and dirty threshold could be suddenly |
153 | * knocked down by a large amount (eg. on the startup of KVM in a |
154 | * swapless system). This may throw the system into deep dirty |
155 | * exceeded state and throttle heavy/light dirtiers alike. To |
156 | * retain good responsiveness, maintain global_dirty_limit for |
157 | * tracking slowly down to the knocked down dirty threshold. |
158 | * |
159 | * Both fields are protected by ->lock. |
160 | */ |
161 | unsigned long dirty_limit_tstamp; |
162 | unsigned long dirty_limit; |
163 | }; |
164 | |
165 | /** |
166 | * wb_domain_size_changed - memory available to a wb_domain has changed |
167 | * @dom: wb_domain of interest |
168 | * |
169 | * This function should be called when the amount of memory available to |
170 | * @dom has changed. It resets @dom's dirty limit parameters to prevent |
171 | * the past values which don't match the current configuration from skewing |
172 | * dirty throttling. Without this, when memory size of a wb_domain is |
173 | * greatly reduced, the dirty throttling logic may allow too many pages to |
174 | * be dirtied leading to consecutive unnecessary OOMs and may get stuck in |
175 | * that situation. |
176 | */ |
177 | static inline void wb_domain_size_changed(struct wb_domain *dom) |
178 | { |
179 | spin_lock(lock: &dom->lock); |
180 | dom->dirty_limit_tstamp = jiffies; |
181 | dom->dirty_limit = 0; |
182 | spin_unlock(lock: &dom->lock); |
183 | } |
184 | |
185 | /* |
186 | * fs/fs-writeback.c |
187 | */ |
188 | struct bdi_writeback; |
189 | void writeback_inodes_sb(struct super_block *, enum wb_reason reason); |
190 | void writeback_inodes_sb_nr(struct super_block *, unsigned long nr, |
191 | enum wb_reason reason); |
192 | void try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason); |
193 | void sync_inodes_sb(struct super_block *); |
194 | void wakeup_flusher_threads(enum wb_reason reason); |
195 | void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, |
196 | enum wb_reason reason); |
197 | void inode_wait_for_writeback(struct inode *inode); |
198 | void inode_io_list_del(struct inode *inode); |
199 | |
200 | /* writeback.h requires fs.h; it, too, is not included from here. */ |
201 | static inline void wait_on_inode(struct inode *inode) |
202 | { |
203 | wait_on_bit(word: &inode->i_state, __I_NEW, TASK_UNINTERRUPTIBLE); |
204 | } |
205 | |
206 | #ifdef CONFIG_CGROUP_WRITEBACK |
207 | |
208 | #include <linux/cgroup.h> |
209 | #include <linux/bio.h> |
210 | |
211 | void __inode_attach_wb(struct inode *inode, struct folio *folio); |
212 | void wbc_attach_and_unlock_inode(struct writeback_control *wbc, |
213 | struct inode *inode) |
214 | __releases(&inode->i_lock); |
215 | void wbc_detach_inode(struct writeback_control *wbc); |
216 | void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, |
217 | size_t bytes); |
218 | int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, |
219 | enum wb_reason reason, struct wb_completion *done); |
220 | void cgroup_writeback_umount(void); |
221 | bool cleanup_offline_cgwb(struct bdi_writeback *wb); |
222 | |
223 | /** |
224 | * inode_attach_wb - associate an inode with its wb |
225 | * @inode: inode of interest |
226 | * @folio: folio being dirtied (may be NULL) |
227 | * |
228 | * If @inode doesn't have its wb, associate it with the wb matching the |
229 | * memcg of @folio or, if @folio is NULL, %current. May be called w/ or w/o |
230 | * @inode->i_lock. |
231 | */ |
232 | static inline void inode_attach_wb(struct inode *inode, struct folio *folio) |
233 | { |
234 | if (!inode->i_wb) |
235 | __inode_attach_wb(inode, folio); |
236 | } |
237 | |
238 | /** |
239 | * inode_detach_wb - disassociate an inode from its wb |
240 | * @inode: inode of interest |
241 | * |
242 | * @inode is being freed. Detach from its wb. |
243 | */ |
244 | static inline void inode_detach_wb(struct inode *inode) |
245 | { |
246 | if (inode->i_wb) { |
247 | WARN_ON_ONCE(!(inode->i_state & I_CLEAR)); |
248 | wb_put(wb: inode->i_wb); |
249 | inode->i_wb = NULL; |
250 | } |
251 | } |
252 | |
253 | /** |
254 | * wbc_attach_fdatawrite_inode - associate wbc and inode for fdatawrite |
255 | * @wbc: writeback_control of interest |
256 | * @inode: target inode |
257 | * |
258 | * This function is to be used by __filemap_fdatawrite_range(), which is an |
259 | * alternative entry point into writeback code, and first ensures @inode is |
260 | * associated with a bdi_writeback and attaches it to @wbc. |
261 | */ |
262 | static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc, |
263 | struct inode *inode) |
264 | { |
265 | spin_lock(lock: &inode->i_lock); |
266 | inode_attach_wb(inode, NULL); |
267 | wbc_attach_and_unlock_inode(wbc, inode); |
268 | } |
269 | |
270 | /** |
271 | * wbc_init_bio - writeback specific initializtion of bio |
272 | * @wbc: writeback_control for the writeback in progress |
273 | * @bio: bio to be initialized |
274 | * |
275 | * @bio is a part of the writeback in progress controlled by @wbc. Perform |
276 | * writeback specific initialization. This is used to apply the cgroup |
277 | * writeback context. Must be called after the bio has been associated with |
278 | * a device. |
279 | */ |
280 | static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio) |
281 | { |
282 | /* |
283 | * pageout() path doesn't attach @wbc to the inode being written |
284 | * out. This is intentional as we don't want the function to block |
285 | * behind a slow cgroup. Ultimately, we want pageout() to kick off |
286 | * regular writeback instead of writing things out itself. |
287 | */ |
288 | if (wbc->wb) |
289 | bio_associate_blkg_from_css(bio, css: wbc->wb->blkcg_css); |
290 | } |
291 | |
292 | #else /* CONFIG_CGROUP_WRITEBACK */ |
293 | |
294 | static inline void inode_attach_wb(struct inode *inode, struct folio *folio) |
295 | { |
296 | } |
297 | |
298 | static inline void inode_detach_wb(struct inode *inode) |
299 | { |
300 | } |
301 | |
302 | static inline void wbc_attach_and_unlock_inode(struct writeback_control *wbc, |
303 | struct inode *inode) |
304 | __releases(&inode->i_lock) |
305 | { |
306 | spin_unlock(&inode->i_lock); |
307 | } |
308 | |
309 | static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc, |
310 | struct inode *inode) |
311 | { |
312 | } |
313 | |
314 | static inline void wbc_detach_inode(struct writeback_control *wbc) |
315 | { |
316 | } |
317 | |
318 | static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio) |
319 | { |
320 | } |
321 | |
322 | static inline void wbc_account_cgroup_owner(struct writeback_control *wbc, |
323 | struct page *page, size_t bytes) |
324 | { |
325 | } |
326 | |
327 | static inline void cgroup_writeback_umount(void) |
328 | { |
329 | } |
330 | |
331 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
332 | |
333 | /* |
334 | * mm/page-writeback.c |
335 | */ |
336 | void laptop_io_completion(struct backing_dev_info *info); |
337 | void laptop_sync_completion(void); |
338 | void laptop_mode_timer_fn(struct timer_list *t); |
339 | bool node_dirty_ok(struct pglist_data *pgdat); |
340 | int wb_domain_init(struct wb_domain *dom, gfp_t gfp); |
341 | #ifdef CONFIG_CGROUP_WRITEBACK |
342 | void wb_domain_exit(struct wb_domain *dom); |
343 | #endif |
344 | |
345 | extern struct wb_domain global_wb_domain; |
346 | |
347 | /* These are exported to sysctl. */ |
348 | extern unsigned int dirty_writeback_interval; |
349 | extern unsigned int dirty_expire_interval; |
350 | extern unsigned int dirtytime_expire_interval; |
351 | extern int laptop_mode; |
352 | |
353 | int dirtytime_interval_handler(struct ctl_table *table, int write, |
354 | void *buffer, size_t *lenp, loff_t *ppos); |
355 | |
356 | void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); |
357 | unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh); |
358 | |
359 | void wb_update_bandwidth(struct bdi_writeback *wb); |
360 | |
361 | /* Invoke balance dirty pages in async mode. */ |
362 | #define BDP_ASYNC 0x0001 |
363 | |
364 | void balance_dirty_pages_ratelimited(struct address_space *mapping); |
365 | int balance_dirty_pages_ratelimited_flags(struct address_space *mapping, |
366 | unsigned int flags); |
367 | |
368 | bool wb_over_bg_thresh(struct bdi_writeback *wb); |
369 | |
370 | struct folio *writeback_iter(struct address_space *mapping, |
371 | struct writeback_control *wbc, struct folio *folio, int *error); |
372 | |
373 | typedef int (*writepage_t)(struct folio *folio, struct writeback_control *wbc, |
374 | void *data); |
375 | |
376 | int write_cache_pages(struct address_space *mapping, |
377 | struct writeback_control *wbc, writepage_t writepage, |
378 | void *data); |
379 | int do_writepages(struct address_space *mapping, struct writeback_control *wbc); |
380 | void writeback_set_ratelimit(void); |
381 | void tag_pages_for_writeback(struct address_space *mapping, |
382 | pgoff_t start, pgoff_t end); |
383 | |
384 | bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio); |
385 | bool folio_redirty_for_writepage(struct writeback_control *, struct folio *); |
386 | bool redirty_page_for_writepage(struct writeback_control *, struct page *); |
387 | |
388 | void sb_mark_inode_writeback(struct inode *inode); |
389 | void sb_clear_inode_writeback(struct inode *inode); |
390 | |
391 | #endif /* WRITEBACK_H */ |
392 | |