1 /* SPDX-License-Identifier: GPL-2.0 */
3 * include/linux/backing-dev.h
5 * low-level device information and state which is propagated up through
9 #ifndef _LINUX_BACKING_DEV_H
10 #define _LINUX_BACKING_DEV_H
12 #include <linux/kernel.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>
22 static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
24 kref_get(&bdi->refcnt);
28 struct backing_dev_info *bdi_get_by_id(u64 id);
29 void bdi_put(struct backing_dev_info *bdi);
32 int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
34 int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
36 void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner);
37 void bdi_unregister(struct backing_dev_info *bdi);
39 struct backing_dev_info *bdi_alloc(int node_id);
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);
45 void wb_wait_for_completion(struct wb_completion *done);
47 extern spinlock_t bdi_lock;
48 extern struct list_head bdi_list;
50 extern struct workqueue_struct *bdi_wq;
51 extern struct workqueue_struct *bdi_async_bio_wq;
53 static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
55 return test_bit(WB_has_dirty_io, &wb->state);
58 static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
61 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
62 * any dirty wbs. See wb_update_write_bandwidth().
64 return atomic_long_read(&bdi->tot_write_bandwidth);
67 static inline void wb_stat_mod(struct bdi_writeback *wb,
68 enum wb_stat_item item, s64 amount)
70 percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);
73 static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
75 wb_stat_mod(wb, item, 1);
78 static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
80 wb_stat_mod(wb, item, -1);
83 static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
85 return percpu_counter_read_positive(&wb->stat[item]);
88 static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
90 return percpu_counter_sum_positive(&wb->stat[item]);
93 extern void wb_writeout_inc(struct bdi_writeback *wb);
96 * maximal error of a stat counter.
98 static inline unsigned long wb_stat_error(void)
101 return nr_cpu_ids * WB_STAT_BATCH;
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);
111 * Flags in backing_dev_info::capability
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
118 #define BDI_CAP_WRITEBACK (1 << 0)
119 #define BDI_CAP_WRITEBACK_ACCT (1 << 1)
120 #define BDI_CAP_STRICTLIMIT (1 << 2)
122 extern struct backing_dev_info noop_backing_dev_info;
125 * writeback_in_progress - determine whether there is writeback in progress
126 * @wb: bdi_writeback of interest
128 * Determine whether there is writeback waiting to be handled against a
131 static inline bool writeback_in_progress(struct bdi_writeback *wb)
133 return test_bit(WB_writeback_running, &wb->state);
136 struct backing_dev_info *inode_to_bdi(struct inode *inode);
138 static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
140 return wb->congested & cong_bits;
143 long congestion_wait(int sync, long timeout);
145 static inline bool mapping_can_writeback(struct address_space *mapping)
147 return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK;
150 static inline int bdi_sched_wait(void *word)
156 #ifdef CONFIG_CGROUP_WRITEBACK
158 struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
159 struct cgroup_subsys_state *memcg_css);
160 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
161 struct cgroup_subsys_state *memcg_css,
163 void wb_memcg_offline(struct mem_cgroup *memcg);
164 void wb_blkcg_offline(struct blkcg *blkcg);
165 int inode_congested(struct inode *inode, int cong_bits);
168 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
169 * @inode: inode of interest
171 * Cgroup writeback requires support from the filesystem. Also, both memcg and
172 * iocg have to be on the default hierarchy. Test whether all conditions are
175 * Note that the test result may change dynamically on the same inode
176 * depending on how memcg and iocg are configured.
178 static inline bool inode_cgwb_enabled(struct inode *inode)
180 struct backing_dev_info *bdi = inode_to_bdi(inode);
182 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
183 cgroup_subsys_on_dfl(io_cgrp_subsys) &&
184 (bdi->capabilities & BDI_CAP_WRITEBACK) &&
185 (inode->i_sb->s_iflags & SB_I_CGROUPWB);
189 * wb_find_current - find wb for %current on a bdi
190 * @bdi: bdi of interest
192 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
193 * Must be called under rcu_read_lock() which protects the returend wb.
196 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
198 struct cgroup_subsys_state *memcg_css;
199 struct bdi_writeback *wb;
201 memcg_css = task_css(current, memory_cgrp_id);
202 if (!memcg_css->parent)
205 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
208 * %current's blkcg equals the effective blkcg of its memcg. No
209 * need to use the relatively expensive cgroup_get_e_css().
211 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
217 * wb_get_create_current - get or create wb for %current on a bdi
218 * @bdi: bdi of interest
219 * @gfp: allocation mask
221 * Equivalent to wb_get_create() on %current's memcg. This function is
222 * called from a relatively hot path and optimizes the common cases using
225 static inline struct bdi_writeback *
226 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
228 struct bdi_writeback *wb;
231 wb = wb_find_current(bdi);
232 if (wb && unlikely(!wb_tryget(wb)))
237 struct cgroup_subsys_state *memcg_css;
239 memcg_css = task_get_css(current, memory_cgrp_id);
240 wb = wb_get_create(bdi, memcg_css, gfp);
247 * inode_to_wb_is_valid - test whether an inode has a wb associated
248 * @inode: inode of interest
250 * Returns %true if @inode has a wb associated. May be called without any
253 static inline bool inode_to_wb_is_valid(struct inode *inode)
259 * inode_to_wb - determine the wb of an inode
260 * @inode: inode of interest
262 * Returns the wb @inode is currently associated with. The caller must be
263 * holding either @inode->i_lock, the i_pages lock, or the
264 * associated wb's list_lock.
266 static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
268 #ifdef CONFIG_LOCKDEP
269 WARN_ON_ONCE(debug_locks &&
270 (!lockdep_is_held(&inode->i_lock) &&
271 !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&
272 !lockdep_is_held(&inode->i_wb->list_lock)));
277 static inline struct bdi_writeback *inode_to_wb_wbc(
279 struct writeback_control *wbc)
282 * If wbc does not have inode attached, it means cgroup writeback was
283 * disabled when wbc started. Just use the default wb in that case.
285 return wbc->wb ? wbc->wb : &inode_to_bdi(inode)->wb;
289 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
290 * @inode: target inode
291 * @cookie: output param, to be passed to the end function
293 * The caller wants to access the wb associated with @inode but isn't
294 * holding inode->i_lock, the i_pages lock or wb->list_lock. This
295 * function determines the wb associated with @inode and ensures that the
296 * association doesn't change until the transaction is finished with
297 * unlocked_inode_to_wb_end().
299 * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and
300 * can't sleep during the transaction. IRQs may or may not be disabled on
303 static inline struct bdi_writeback *
304 unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
309 * Paired with store_release in inode_switch_wbs_work_fn() and
310 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
312 cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
314 if (unlikely(cookie->locked))
315 xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);
318 * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages
319 * lock. inode_to_wb() will bark. Deref directly.
325 * unlocked_inode_to_wb_end - end inode wb access transaction
326 * @inode: target inode
327 * @cookie: @cookie from unlocked_inode_to_wb_begin()
329 static inline void unlocked_inode_to_wb_end(struct inode *inode,
330 struct wb_lock_cookie *cookie)
332 if (unlikely(cookie->locked))
333 xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags);
338 #else /* CONFIG_CGROUP_WRITEBACK */
340 static inline bool inode_cgwb_enabled(struct inode *inode)
345 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
350 static inline struct bdi_writeback *
351 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
356 static inline bool inode_to_wb_is_valid(struct inode *inode)
361 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
363 return &inode_to_bdi(inode)->wb;
366 static inline struct bdi_writeback *inode_to_wb_wbc(
368 struct writeback_control *wbc)
370 return inode_to_wb(inode);
374 static inline struct bdi_writeback *
375 unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
377 return inode_to_wb(inode);
380 static inline void unlocked_inode_to_wb_end(struct inode *inode,
381 struct wb_lock_cookie *cookie)
385 static inline void wb_memcg_offline(struct mem_cgroup *memcg)
389 static inline void wb_blkcg_offline(struct blkcg *blkcg)
393 static inline int inode_congested(struct inode *inode, int cong_bits)
395 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
398 #endif /* CONFIG_CGROUP_WRITEBACK */
400 static inline int inode_read_congested(struct inode *inode)
402 return inode_congested(inode, 1 << WB_sync_congested);
405 static inline int inode_write_congested(struct inode *inode)
407 return inode_congested(inode, 1 << WB_async_congested);
410 static inline int inode_rw_congested(struct inode *inode)
412 return inode_congested(inode, (1 << WB_sync_congested) |
413 (1 << WB_async_congested));
416 static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
418 return wb_congested(&bdi->wb, cong_bits);
421 static inline int bdi_read_congested(struct backing_dev_info *bdi)
423 return bdi_congested(bdi, 1 << WB_sync_congested);
426 static inline int bdi_write_congested(struct backing_dev_info *bdi)
428 return bdi_congested(bdi, 1 << WB_async_congested);
431 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
433 return bdi_congested(bdi, (1 << WB_sync_congested) |
434 (1 << WB_async_congested));
437 const char *bdi_dev_name(struct backing_dev_info *bdi);
439 #endif /* _LINUX_BACKING_DEV_H */