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/device.h> |
16 | #include <linux/writeback.h> |
17 | #include <linux/backing-dev-defs.h> |
18 | #include <linux/slab.h> |
19 | |
20 | static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi) |
21 | { |
22 | kref_get(kref: &bdi->refcnt); |
23 | return bdi; |
24 | } |
25 | |
26 | struct backing_dev_info *bdi_get_by_id(u64 id); |
27 | void bdi_put(struct backing_dev_info *bdi); |
28 | |
29 | __printf(2, 3) |
30 | int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...); |
31 | __printf(2, 0) |
32 | int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, |
33 | va_list args); |
34 | void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner); |
35 | void bdi_unregister(struct backing_dev_info *bdi); |
36 | |
37 | struct backing_dev_info *bdi_alloc(int node_id); |
38 | |
39 | void wb_start_background_writeback(struct bdi_writeback *wb); |
40 | void wb_workfn(struct work_struct *work); |
41 | |
42 | void wb_wait_for_completion(struct wb_completion *done); |
43 | |
44 | extern spinlock_t bdi_lock; |
45 | extern struct list_head bdi_list; |
46 | |
47 | extern struct workqueue_struct *bdi_wq; |
48 | |
49 | static inline bool wb_has_dirty_io(struct bdi_writeback *wb) |
50 | { |
51 | return test_bit(WB_has_dirty_io, &wb->state); |
52 | } |
53 | |
54 | static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi) |
55 | { |
56 | /* |
57 | * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are |
58 | * any dirty wbs. See wb_update_write_bandwidth(). |
59 | */ |
60 | return atomic_long_read(v: &bdi->tot_write_bandwidth); |
61 | } |
62 | |
63 | static inline void wb_stat_mod(struct bdi_writeback *wb, |
64 | enum wb_stat_item item, s64 amount) |
65 | { |
66 | percpu_counter_add_batch(fbc: &wb->stat[item], amount, WB_STAT_BATCH); |
67 | } |
68 | |
69 | static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item) |
70 | { |
71 | wb_stat_mod(wb, item, amount: 1); |
72 | } |
73 | |
74 | static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item) |
75 | { |
76 | wb_stat_mod(wb, item, amount: -1); |
77 | } |
78 | |
79 | static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item) |
80 | { |
81 | return percpu_counter_read_positive(fbc: &wb->stat[item]); |
82 | } |
83 | |
84 | static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item) |
85 | { |
86 | return percpu_counter_sum_positive(fbc: &wb->stat[item]); |
87 | } |
88 | |
89 | extern void wb_writeout_inc(struct bdi_writeback *wb); |
90 | |
91 | /* |
92 | * maximal error of a stat counter. |
93 | */ |
94 | static inline unsigned long wb_stat_error(void) |
95 | { |
96 | #ifdef CONFIG_SMP |
97 | return nr_cpu_ids * WB_STAT_BATCH; |
98 | #else |
99 | return 1; |
100 | #endif |
101 | } |
102 | |
103 | /* BDI ratio is expressed as part per 1000000 for finer granularity. */ |
104 | #define BDI_RATIO_SCALE 10000 |
105 | |
106 | u64 bdi_get_min_bytes(struct backing_dev_info *bdi); |
107 | u64 bdi_get_max_bytes(struct backing_dev_info *bdi); |
108 | int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); |
109 | int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); |
110 | int bdi_set_min_ratio_no_scale(struct backing_dev_info *bdi, unsigned int min_ratio); |
111 | int bdi_set_max_ratio_no_scale(struct backing_dev_info *bdi, unsigned int max_ratio); |
112 | int bdi_set_min_bytes(struct backing_dev_info *bdi, u64 min_bytes); |
113 | int bdi_set_max_bytes(struct backing_dev_info *bdi, u64 max_bytes); |
114 | int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit); |
115 | |
116 | /* |
117 | * Flags in backing_dev_info::capability |
118 | * |
119 | * BDI_CAP_WRITEBACK: Supports dirty page writeback, and dirty pages |
120 | * should contribute to accounting |
121 | * BDI_CAP_WRITEBACK_ACCT: Automatically account writeback pages |
122 | * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold |
123 | */ |
124 | #define BDI_CAP_WRITEBACK (1 << 0) |
125 | #define BDI_CAP_WRITEBACK_ACCT (1 << 1) |
126 | #define BDI_CAP_STRICTLIMIT (1 << 2) |
127 | |
128 | extern struct backing_dev_info noop_backing_dev_info; |
129 | |
130 | int bdi_init(struct backing_dev_info *bdi); |
131 | |
132 | /** |
133 | * writeback_in_progress - determine whether there is writeback in progress |
134 | * @wb: bdi_writeback of interest |
135 | * |
136 | * Determine whether there is writeback waiting to be handled against a |
137 | * bdi_writeback. |
138 | */ |
139 | static inline bool writeback_in_progress(struct bdi_writeback *wb) |
140 | { |
141 | return test_bit(WB_writeback_running, &wb->state); |
142 | } |
143 | |
144 | struct backing_dev_info *inode_to_bdi(struct inode *inode); |
145 | |
146 | static inline bool mapping_can_writeback(struct address_space *mapping) |
147 | { |
148 | return inode_to_bdi(inode: mapping->host)->capabilities & BDI_CAP_WRITEBACK; |
149 | } |
150 | |
151 | #ifdef CONFIG_CGROUP_WRITEBACK |
152 | |
153 | struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, |
154 | struct cgroup_subsys_state *memcg_css); |
155 | struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, |
156 | struct cgroup_subsys_state *memcg_css, |
157 | gfp_t gfp); |
158 | void wb_memcg_offline(struct mem_cgroup *memcg); |
159 | void wb_blkcg_offline(struct cgroup_subsys_state *css); |
160 | |
161 | /** |
162 | * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode |
163 | * @inode: inode of interest |
164 | * |
165 | * Cgroup writeback requires support from the filesystem. Also, both memcg and |
166 | * iocg have to be on the default hierarchy. Test whether all conditions are |
167 | * met. |
168 | * |
169 | * Note that the test result may change dynamically on the same inode |
170 | * depending on how memcg and iocg are configured. |
171 | */ |
172 | static inline bool inode_cgwb_enabled(struct inode *inode) |
173 | { |
174 | struct backing_dev_info *bdi = inode_to_bdi(inode); |
175 | |
176 | return cgroup_subsys_on_dfl(memory_cgrp_subsys) && |
177 | cgroup_subsys_on_dfl(io_cgrp_subsys) && |
178 | (bdi->capabilities & BDI_CAP_WRITEBACK) && |
179 | (inode->i_sb->s_iflags & SB_I_CGROUPWB); |
180 | } |
181 | |
182 | /** |
183 | * wb_find_current - find wb for %current on a bdi |
184 | * @bdi: bdi of interest |
185 | * |
186 | * Find the wb of @bdi which matches both the memcg and blkcg of %current. |
187 | * Must be called under rcu_read_lock() which protects the returend wb. |
188 | * NULL if not found. |
189 | */ |
190 | static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi) |
191 | { |
192 | struct cgroup_subsys_state *memcg_css; |
193 | struct bdi_writeback *wb; |
194 | |
195 | memcg_css = task_css(current, subsys_id: memory_cgrp_id); |
196 | if (!memcg_css->parent) |
197 | return &bdi->wb; |
198 | |
199 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); |
200 | |
201 | /* |
202 | * %current's blkcg equals the effective blkcg of its memcg. No |
203 | * need to use the relatively expensive cgroup_get_e_css(). |
204 | */ |
205 | if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id))) |
206 | return wb; |
207 | return NULL; |
208 | } |
209 | |
210 | /** |
211 | * wb_get_create_current - get or create wb for %current on a bdi |
212 | * @bdi: bdi of interest |
213 | * @gfp: allocation mask |
214 | * |
215 | * Equivalent to wb_get_create() on %current's memcg. This function is |
216 | * called from a relatively hot path and optimizes the common cases using |
217 | * wb_find_current(). |
218 | */ |
219 | static inline struct bdi_writeback * |
220 | wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp) |
221 | { |
222 | struct bdi_writeback *wb; |
223 | |
224 | rcu_read_lock(); |
225 | wb = wb_find_current(bdi); |
226 | if (wb && unlikely(!wb_tryget(wb))) |
227 | wb = NULL; |
228 | rcu_read_unlock(); |
229 | |
230 | if (unlikely(!wb)) { |
231 | struct cgroup_subsys_state *memcg_css; |
232 | |
233 | memcg_css = task_get_css(current, subsys_id: memory_cgrp_id); |
234 | wb = wb_get_create(bdi, memcg_css, gfp); |
235 | css_put(css: memcg_css); |
236 | } |
237 | return wb; |
238 | } |
239 | |
240 | /** |
241 | * inode_to_wb - determine the wb of an inode |
242 | * @inode: inode of interest |
243 | * |
244 | * Returns the wb @inode is currently associated with. The caller must be |
245 | * holding either @inode->i_lock, the i_pages lock, or the |
246 | * associated wb's list_lock. |
247 | */ |
248 | static inline struct bdi_writeback *inode_to_wb(const struct inode *inode) |
249 | { |
250 | #ifdef CONFIG_LOCKDEP |
251 | WARN_ON_ONCE(debug_locks && |
252 | (!lockdep_is_held(&inode->i_lock) && |
253 | !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) && |
254 | !lockdep_is_held(&inode->i_wb->list_lock))); |
255 | #endif |
256 | return inode->i_wb; |
257 | } |
258 | |
259 | static inline struct bdi_writeback *inode_to_wb_wbc( |
260 | struct inode *inode, |
261 | struct writeback_control *wbc) |
262 | { |
263 | /* |
264 | * If wbc does not have inode attached, it means cgroup writeback was |
265 | * disabled when wbc started. Just use the default wb in that case. |
266 | */ |
267 | return wbc->wb ? wbc->wb : &inode_to_bdi(inode)->wb; |
268 | } |
269 | |
270 | /** |
271 | * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction |
272 | * @inode: target inode |
273 | * @cookie: output param, to be passed to the end function |
274 | * |
275 | * The caller wants to access the wb associated with @inode but isn't |
276 | * holding inode->i_lock, the i_pages lock or wb->list_lock. This |
277 | * function determines the wb associated with @inode and ensures that the |
278 | * association doesn't change until the transaction is finished with |
279 | * unlocked_inode_to_wb_end(). |
280 | * |
281 | * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and |
282 | * can't sleep during the transaction. IRQs may or may not be disabled on |
283 | * return. |
284 | */ |
285 | static inline struct bdi_writeback * |
286 | unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie) |
287 | { |
288 | rcu_read_lock(); |
289 | |
290 | /* |
291 | * Paired with store_release in inode_switch_wbs_work_fn() and |
292 | * ensures that we see the new wb if we see cleared I_WB_SWITCH. |
293 | */ |
294 | cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH; |
295 | |
296 | if (unlikely(cookie->locked)) |
297 | xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags); |
298 | |
299 | /* |
300 | * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages |
301 | * lock. inode_to_wb() will bark. Deref directly. |
302 | */ |
303 | return inode->i_wb; |
304 | } |
305 | |
306 | /** |
307 | * unlocked_inode_to_wb_end - end inode wb access transaction |
308 | * @inode: target inode |
309 | * @cookie: @cookie from unlocked_inode_to_wb_begin() |
310 | */ |
311 | static inline void unlocked_inode_to_wb_end(struct inode *inode, |
312 | struct wb_lock_cookie *cookie) |
313 | { |
314 | if (unlikely(cookie->locked)) |
315 | xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags); |
316 | |
317 | rcu_read_unlock(); |
318 | } |
319 | |
320 | #else /* CONFIG_CGROUP_WRITEBACK */ |
321 | |
322 | static inline bool inode_cgwb_enabled(struct inode *inode) |
323 | { |
324 | return false; |
325 | } |
326 | |
327 | static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi) |
328 | { |
329 | return &bdi->wb; |
330 | } |
331 | |
332 | static inline struct bdi_writeback * |
333 | wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp) |
334 | { |
335 | return &bdi->wb; |
336 | } |
337 | |
338 | static inline struct bdi_writeback *inode_to_wb(struct inode *inode) |
339 | { |
340 | return &inode_to_bdi(inode)->wb; |
341 | } |
342 | |
343 | static inline struct bdi_writeback *inode_to_wb_wbc( |
344 | struct inode *inode, |
345 | struct writeback_control *wbc) |
346 | { |
347 | return inode_to_wb(inode); |
348 | } |
349 | |
350 | |
351 | static inline struct bdi_writeback * |
352 | unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie) |
353 | { |
354 | return inode_to_wb(inode); |
355 | } |
356 | |
357 | static inline void unlocked_inode_to_wb_end(struct inode *inode, |
358 | struct wb_lock_cookie *cookie) |
359 | { |
360 | } |
361 | |
362 | static inline void wb_memcg_offline(struct mem_cgroup *memcg) |
363 | { |
364 | } |
365 | |
366 | static inline void wb_blkcg_offline(struct cgroup_subsys_state *css) |
367 | { |
368 | } |
369 | |
370 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
371 | |
372 | const char *bdi_dev_name(struct backing_dev_info *bdi); |
373 | |
374 | #endif /* _LINUX_BACKING_DEV_H */ |
375 | |