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/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>
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 __add_wb_stat(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 __add_wb_stat(wb, item, 1);
78 static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
80 __add_wb_stat(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;
124 int bdi_init(struct backing_dev_info *bdi);
127 * writeback_in_progress - determine whether there is writeback in progress
128 * @wb: bdi_writeback of interest
130 * Determine whether there is writeback waiting to be handled against a
133 static inline bool writeback_in_progress(struct bdi_writeback *wb)
135 return test_bit(WB_writeback_running, &wb->state);
138 static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
140 struct super_block *sb;
143 return &noop_backing_dev_info;
147 if (sb_is_blkdev_sb(sb))
148 return I_BDEV(inode)->bd_disk->bdi;
153 static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
155 return wb->congested & cong_bits;
158 long congestion_wait(int sync, long timeout);
159 long wait_iff_congested(int sync, long timeout);
161 static inline bool mapping_can_writeback(struct address_space *mapping)
163 return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK;
166 static inline int bdi_sched_wait(void *word)
172 #ifdef CONFIG_CGROUP_WRITEBACK
174 struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
175 struct cgroup_subsys_state *memcg_css);
176 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
177 struct cgroup_subsys_state *memcg_css,
179 void wb_memcg_offline(struct mem_cgroup *memcg);
180 void wb_blkcg_offline(struct blkcg *blkcg);
181 int inode_congested(struct inode *inode, int cong_bits);
184 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
185 * @inode: inode of interest
187 * Cgroup writeback requires support from the filesystem. Also, both memcg and
188 * iocg have to be on the default hierarchy. Test whether all conditions are
191 * Note that the test result may change dynamically on the same inode
192 * depending on how memcg and iocg are configured.
194 static inline bool inode_cgwb_enabled(struct inode *inode)
196 struct backing_dev_info *bdi = inode_to_bdi(inode);
198 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
199 cgroup_subsys_on_dfl(io_cgrp_subsys) &&
200 (bdi->capabilities & BDI_CAP_WRITEBACK) &&
201 (inode->i_sb->s_iflags & SB_I_CGROUPWB);
205 * wb_find_current - find wb for %current on a bdi
206 * @bdi: bdi of interest
208 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
209 * Must be called under rcu_read_lock() which protects the returend wb.
212 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
214 struct cgroup_subsys_state *memcg_css;
215 struct bdi_writeback *wb;
217 memcg_css = task_css(current, memory_cgrp_id);
218 if (!memcg_css->parent)
221 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
224 * %current's blkcg equals the effective blkcg of its memcg. No
225 * need to use the relatively expensive cgroup_get_e_css().
227 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
233 * wb_get_create_current - get or create wb for %current on a bdi
234 * @bdi: bdi of interest
235 * @gfp: allocation mask
237 * Equivalent to wb_get_create() on %current's memcg. This function is
238 * called from a relatively hot path and optimizes the common cases using
241 static inline struct bdi_writeback *
242 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
244 struct bdi_writeback *wb;
247 wb = wb_find_current(bdi);
248 if (wb && unlikely(!wb_tryget(wb)))
253 struct cgroup_subsys_state *memcg_css;
255 memcg_css = task_get_css(current, memory_cgrp_id);
256 wb = wb_get_create(bdi, memcg_css, gfp);
263 * inode_to_wb_is_valid - test whether an inode has a wb associated
264 * @inode: inode of interest
266 * Returns %true if @inode has a wb associated. May be called without any
269 static inline bool inode_to_wb_is_valid(struct inode *inode)
275 * inode_to_wb - determine the wb of an inode
276 * @inode: inode of interest
278 * Returns the wb @inode is currently associated with. The caller must be
279 * holding either @inode->i_lock, the i_pages lock, or the
280 * associated wb's list_lock.
282 static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
284 #ifdef CONFIG_LOCKDEP
285 WARN_ON_ONCE(debug_locks &&
286 (!lockdep_is_held(&inode->i_lock) &&
287 !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&
288 !lockdep_is_held(&inode->i_wb->list_lock)));
293 static inline struct bdi_writeback *inode_to_wb_wbc(
295 struct writeback_control *wbc)
298 * If wbc does not have inode attached, it means cgroup writeback was
299 * disabled when wbc started. Just use the default wb in that case.
301 return wbc->wb ? wbc->wb : &inode_to_bdi(inode)->wb;
305 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
306 * @inode: target inode
307 * @cookie: output param, to be passed to the end function
309 * The caller wants to access the wb associated with @inode but isn't
310 * holding inode->i_lock, the i_pages lock or wb->list_lock. This
311 * function determines the wb associated with @inode and ensures that the
312 * association doesn't change until the transaction is finished with
313 * unlocked_inode_to_wb_end().
315 * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and
316 * can't sleep during the transaction. IRQs may or may not be disabled on
319 static inline struct bdi_writeback *
320 unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
325 * Paired with store_release in inode_switch_wbs_work_fn() and
326 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
328 cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
330 if (unlikely(cookie->locked))
331 xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);
334 * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages
335 * lock. inode_to_wb() will bark. Deref directly.
341 * unlocked_inode_to_wb_end - end inode wb access transaction
342 * @inode: target inode
343 * @cookie: @cookie from unlocked_inode_to_wb_begin()
345 static inline void unlocked_inode_to_wb_end(struct inode *inode,
346 struct wb_lock_cookie *cookie)
348 if (unlikely(cookie->locked))
349 xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags);
354 #else /* CONFIG_CGROUP_WRITEBACK */
356 static inline bool inode_cgwb_enabled(struct inode *inode)
361 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
366 static inline struct bdi_writeback *
367 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
372 static inline bool inode_to_wb_is_valid(struct inode *inode)
377 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
379 return &inode_to_bdi(inode)->wb;
382 static inline struct bdi_writeback *inode_to_wb_wbc(
384 struct writeback_control *wbc)
386 return inode_to_wb(inode);
390 static inline struct bdi_writeback *
391 unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
393 return inode_to_wb(inode);
396 static inline void unlocked_inode_to_wb_end(struct inode *inode,
397 struct wb_lock_cookie *cookie)
401 static inline void wb_memcg_offline(struct mem_cgroup *memcg)
405 static inline void wb_blkcg_offline(struct blkcg *blkcg)
409 static inline int inode_congested(struct inode *inode, int cong_bits)
411 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
414 #endif /* CONFIG_CGROUP_WRITEBACK */
416 static inline int inode_read_congested(struct inode *inode)
418 return inode_congested(inode, 1 << WB_sync_congested);
421 static inline int inode_write_congested(struct inode *inode)
423 return inode_congested(inode, 1 << WB_async_congested);
426 static inline int inode_rw_congested(struct inode *inode)
428 return inode_congested(inode, (1 << WB_sync_congested) |
429 (1 << WB_async_congested));
432 static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
434 return wb_congested(&bdi->wb, cong_bits);
437 static inline int bdi_read_congested(struct backing_dev_info *bdi)
439 return bdi_congested(bdi, 1 << WB_sync_congested);
442 static inline int bdi_write_congested(struct backing_dev_info *bdi)
444 return bdi_congested(bdi, 1 << WB_async_congested);
447 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
449 return bdi_congested(bdi, (1 << WB_sync_congested) |
450 (1 << WB_async_congested));
453 const char *bdi_dev_name(struct backing_dev_info *bdi);
455 #endif /* _LINUX_BACKING_DEV_H */