Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : /*
3 : * include/linux/backing-dev.h
4 : *
5 : * low-level device information and state which is propagated up through
6 : * to high-level code.
7 : */
8 :
9 : #ifndef _LINUX_BACKING_DEV_H
10 : #define _LINUX_BACKING_DEV_H
11 :
12 : #include <linux/kernel.h>
13 : #include <linux/fs.h>
14 : #include <linux/sched.h>
15 : #include <linux/blkdev.h>
16 : #include <linux/device.h>
17 : #include <linux/writeback.h>
18 : #include <linux/blk-cgroup.h>
19 : #include <linux/backing-dev-defs.h>
20 : #include <linux/slab.h>
21 :
22 12 : static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
23 : {
24 12 : kref_get(&bdi->refcnt);
25 12 : return bdi;
26 : }
27 :
28 : struct backing_dev_info *bdi_get_by_id(u64 id);
29 : void bdi_put(struct backing_dev_info *bdi);
30 :
31 : __printf(2, 3)
32 : int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
33 : __printf(2, 0)
34 : int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
35 : va_list args);
36 : void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner);
37 : void bdi_unregister(struct backing_dev_info *bdi);
38 :
39 : struct backing_dev_info *bdi_alloc(int node_id);
40 :
41 : void wb_start_background_writeback(struct bdi_writeback *wb);
42 : void wb_workfn(struct work_struct *work);
43 : void wb_wakeup_delayed(struct bdi_writeback *wb);
44 :
45 : void wb_wait_for_completion(struct wb_completion *done);
46 :
47 : extern spinlock_t bdi_lock;
48 : extern struct list_head bdi_list;
49 :
50 : extern struct workqueue_struct *bdi_wq;
51 : extern struct workqueue_struct *bdi_async_bio_wq;
52 :
53 3746 : static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
54 : {
55 3746 : return test_bit(WB_has_dirty_io, &wb->state);
56 : }
57 :
58 101 : static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
59 : {
60 : /*
61 : * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
62 : * any dirty wbs. See wb_update_write_bandwidth().
63 : */
64 101 : return atomic_long_read(&bdi->tot_write_bandwidth);
65 : }
66 :
67 10622 : static inline void __add_wb_stat(struct bdi_writeback *wb,
68 : enum wb_stat_item item, s64 amount)
69 : {
70 10622 : percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);
71 10622 : }
72 :
73 7554 : static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
74 : {
75 5061 : __add_wb_stat(wb, item, 1);
76 1284 : }
77 :
78 3068 : static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
79 : {
80 3068 : __add_wb_stat(wb, item, -1);
81 : }
82 :
83 7 : static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
84 : {
85 7 : return percpu_counter_read_positive(&wb->stat[item]);
86 : }
87 :
88 0 : static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
89 : {
90 0 : return percpu_counter_sum_positive(&wb->stat[item]);
91 : }
92 :
93 : extern void wb_writeout_inc(struct bdi_writeback *wb);
94 :
95 : /*
96 : * maximal error of a stat counter.
97 : */
98 0 : static inline unsigned long wb_stat_error(void)
99 : {
100 : #ifdef CONFIG_SMP
101 0 : return nr_cpu_ids * WB_STAT_BATCH;
102 : #else
103 : return 1;
104 : #endif
105 : }
106 :
107 : int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
108 : int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
109 :
110 : /*
111 : * Flags in backing_dev_info::capability
112 : *
113 : * BDI_CAP_WRITEBACK: Supports dirty page writeback, and dirty pages
114 : * should contribute to accounting
115 : * BDI_CAP_WRITEBACK_ACCT: Automatically account writeback pages
116 : * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold
117 : */
118 : #define BDI_CAP_WRITEBACK (1 << 0)
119 : #define BDI_CAP_WRITEBACK_ACCT (1 << 1)
120 : #define BDI_CAP_STRICTLIMIT (1 << 2)
121 :
122 : extern struct backing_dev_info noop_backing_dev_info;
123 :
124 : /**
125 : * writeback_in_progress - determine whether there is writeback in progress
126 : * @wb: bdi_writeback of interest
127 : *
128 : * Determine whether there is writeback waiting to be handled against a
129 : * bdi_writeback.
130 : */
131 25 : static inline bool writeback_in_progress(struct bdi_writeback *wb)
132 : {
133 25 : return test_bit(WB_writeback_running, &wb->state);
134 : }
135 :
136 40884 : static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
137 : {
138 40884 : struct super_block *sb;
139 :
140 40884 : if (!inode)
141 : return &noop_backing_dev_info;
142 :
143 40884 : sb = inode->i_sb;
144 : #ifdef CONFIG_BLOCK
145 40884 : if (sb_is_blkdev_sb(sb))
146 8029 : return I_BDEV(inode)->bd_bdi;
147 : #endif
148 32855 : return sb->s_bdi;
149 : }
150 :
151 815 : static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
152 : {
153 815 : return wb->congested & cong_bits;
154 : }
155 :
156 : long congestion_wait(int sync, long timeout);
157 : long wait_iff_congested(int sync, long timeout);
158 :
159 5447 : static inline bool mapping_can_writeback(struct address_space *mapping)
160 : {
161 5447 : return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK;
162 : }
163 :
164 : static inline int bdi_sched_wait(void *word)
165 : {
166 : schedule();
167 : return 0;
168 : }
169 :
170 : #ifdef CONFIG_CGROUP_WRITEBACK
171 :
172 : struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
173 : struct cgroup_subsys_state *memcg_css);
174 : struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
175 : struct cgroup_subsys_state *memcg_css,
176 : gfp_t gfp);
177 : void wb_memcg_offline(struct mem_cgroup *memcg);
178 : void wb_blkcg_offline(struct blkcg *blkcg);
179 : int inode_congested(struct inode *inode, int cong_bits);
180 :
181 : /**
182 : * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
183 : * @inode: inode of interest
184 : *
185 : * Cgroup writeback requires support from the filesystem. Also, both memcg and
186 : * iocg have to be on the default hierarchy. Test whether all conditions are
187 : * met.
188 : *
189 : * Note that the test result may change dynamically on the same inode
190 : * depending on how memcg and iocg are configured.
191 : */
192 : static inline bool inode_cgwb_enabled(struct inode *inode)
193 : {
194 : struct backing_dev_info *bdi = inode_to_bdi(inode);
195 :
196 : return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
197 : cgroup_subsys_on_dfl(io_cgrp_subsys) &&
198 : (bdi->capabilities & BDI_CAP_WRITEBACK) &&
199 : (inode->i_sb->s_iflags & SB_I_CGROUPWB);
200 : }
201 :
202 : /**
203 : * wb_find_current - find wb for %current on a bdi
204 : * @bdi: bdi of interest
205 : *
206 : * Find the wb of @bdi which matches both the memcg and blkcg of %current.
207 : * Must be called under rcu_read_lock() which protects the returend wb.
208 : * NULL if not found.
209 : */
210 : static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
211 : {
212 : struct cgroup_subsys_state *memcg_css;
213 : struct bdi_writeback *wb;
214 :
215 : memcg_css = task_css(current, memory_cgrp_id);
216 : if (!memcg_css->parent)
217 : return &bdi->wb;
218 :
219 : wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
220 :
221 : /*
222 : * %current's blkcg equals the effective blkcg of its memcg. No
223 : * need to use the relatively expensive cgroup_get_e_css().
224 : */
225 : if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
226 : return wb;
227 : return NULL;
228 : }
229 :
230 : /**
231 : * wb_get_create_current - get or create wb for %current on a bdi
232 : * @bdi: bdi of interest
233 : * @gfp: allocation mask
234 : *
235 : * Equivalent to wb_get_create() on %current's memcg. This function is
236 : * called from a relatively hot path and optimizes the common cases using
237 : * wb_find_current().
238 : */
239 : static inline struct bdi_writeback *
240 : wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
241 : {
242 : struct bdi_writeback *wb;
243 :
244 : rcu_read_lock();
245 : wb = wb_find_current(bdi);
246 : if (wb && unlikely(!wb_tryget(wb)))
247 : wb = NULL;
248 : rcu_read_unlock();
249 :
250 : if (unlikely(!wb)) {
251 : struct cgroup_subsys_state *memcg_css;
252 :
253 : memcg_css = task_get_css(current, memory_cgrp_id);
254 : wb = wb_get_create(bdi, memcg_css, gfp);
255 : css_put(memcg_css);
256 : }
257 : return wb;
258 : }
259 :
260 : /**
261 : * inode_to_wb_is_valid - test whether an inode has a wb associated
262 : * @inode: inode of interest
263 : *
264 : * Returns %true if @inode has a wb associated. May be called without any
265 : * locking.
266 : */
267 : static inline bool inode_to_wb_is_valid(struct inode *inode)
268 : {
269 : return inode->i_wb;
270 : }
271 :
272 : /**
273 : * inode_to_wb - determine the wb of an inode
274 : * @inode: inode of interest
275 : *
276 : * Returns the wb @inode is currently associated with. The caller must be
277 : * holding either @inode->i_lock, the i_pages lock, or the
278 : * associated wb's list_lock.
279 : */
280 : static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
281 : {
282 : #ifdef CONFIG_LOCKDEP
283 : WARN_ON_ONCE(debug_locks &&
284 : (!lockdep_is_held(&inode->i_lock) &&
285 : !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&
286 : !lockdep_is_held(&inode->i_wb->list_lock)));
287 : #endif
288 : return inode->i_wb;
289 : }
290 :
291 : /**
292 : * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
293 : * @inode: target inode
294 : * @cookie: output param, to be passed to the end function
295 : *
296 : * The caller wants to access the wb associated with @inode but isn't
297 : * holding inode->i_lock, the i_pages lock or wb->list_lock. This
298 : * function determines the wb associated with @inode and ensures that the
299 : * association doesn't change until the transaction is finished with
300 : * unlocked_inode_to_wb_end().
301 : *
302 : * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and
303 : * can't sleep during the transaction. IRQs may or may not be disabled on
304 : * return.
305 : */
306 : static inline struct bdi_writeback *
307 : unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
308 : {
309 : rcu_read_lock();
310 :
311 : /*
312 : * Paired with store_release in inode_switch_wbs_work_fn() and
313 : * ensures that we see the new wb if we see cleared I_WB_SWITCH.
314 : */
315 : cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
316 :
317 : if (unlikely(cookie->locked))
318 : xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);
319 :
320 : /*
321 : * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages
322 : * lock. inode_to_wb() will bark. Deref directly.
323 : */
324 : return inode->i_wb;
325 : }
326 :
327 : /**
328 : * unlocked_inode_to_wb_end - end inode wb access transaction
329 : * @inode: target inode
330 : * @cookie: @cookie from unlocked_inode_to_wb_begin()
331 : */
332 : static inline void unlocked_inode_to_wb_end(struct inode *inode,
333 : struct wb_lock_cookie *cookie)
334 : {
335 : if (unlikely(cookie->locked))
336 : xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags);
337 :
338 : rcu_read_unlock();
339 : }
340 :
341 : #else /* CONFIG_CGROUP_WRITEBACK */
342 :
343 2181 : static inline bool inode_cgwb_enabled(struct inode *inode)
344 : {
345 2181 : return false;
346 : }
347 :
348 : static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
349 : {
350 : return &bdi->wb;
351 : }
352 :
353 : static inline struct bdi_writeback *
354 : wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
355 : {
356 : return &bdi->wb;
357 : }
358 :
359 : static inline bool inode_to_wb_is_valid(struct inode *inode)
360 : {
361 : return true;
362 : }
363 :
364 10577 : static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
365 : {
366 8793 : return &inode_to_bdi(inode)->wb;
367 : }
368 :
369 : static inline struct bdi_writeback *
370 1784 : unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
371 : {
372 1784 : return inode_to_wb(inode);
373 : }
374 :
375 1784 : static inline void unlocked_inode_to_wb_end(struct inode *inode,
376 : struct wb_lock_cookie *cookie)
377 : {
378 1784 : }
379 :
380 : static inline void wb_memcg_offline(struct mem_cgroup *memcg)
381 : {
382 : }
383 :
384 : static inline void wb_blkcg_offline(struct blkcg *blkcg)
385 : {
386 : }
387 :
388 815 : static inline int inode_congested(struct inode *inode, int cong_bits)
389 : {
390 1630 : return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
391 : }
392 :
393 : #endif /* CONFIG_CGROUP_WRITEBACK */
394 :
395 815 : static inline int inode_read_congested(struct inode *inode)
396 : {
397 815 : return inode_congested(inode, 1 << WB_sync_congested);
398 : }
399 :
400 0 : static inline int inode_write_congested(struct inode *inode)
401 : {
402 0 : return inode_congested(inode, 1 << WB_async_congested);
403 : }
404 :
405 : static inline int inode_rw_congested(struct inode *inode)
406 : {
407 : return inode_congested(inode, (1 << WB_sync_congested) |
408 : (1 << WB_async_congested));
409 : }
410 :
411 0 : static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
412 : {
413 0 : return wb_congested(&bdi->wb, cong_bits);
414 : }
415 :
416 : static inline int bdi_read_congested(struct backing_dev_info *bdi)
417 : {
418 : return bdi_congested(bdi, 1 << WB_sync_congested);
419 : }
420 :
421 0 : static inline int bdi_write_congested(struct backing_dev_info *bdi)
422 : {
423 0 : return bdi_congested(bdi, 1 << WB_async_congested);
424 : }
425 :
426 : static inline int bdi_rw_congested(struct backing_dev_info *bdi)
427 : {
428 : return bdi_congested(bdi, (1 << WB_sync_congested) |
429 : (1 << WB_async_congested));
430 : }
431 :
432 : const char *bdi_dev_name(struct backing_dev_info *bdi);
433 :
434 : #endif /* _LINUX_BACKING_DEV_H */
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