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/writeback.h>
17 #include <linux/blk-cgroup.h>
18 #include <linux/backing-dev-defs.h>
19 #include <linux/slab.h>
21 static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
23 kref_get(&bdi->refcnt);
27 struct backing_dev_info *bdi_get_by_id(u64 id);
28 void bdi_put(struct backing_dev_info *bdi);
31 int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
33 int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
35 int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
36 void bdi_unregister(struct backing_dev_info *bdi);
38 struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
39 static inline struct backing_dev_info *bdi_alloc(gfp_t gfp_mask)
41 return bdi_alloc_node(gfp_mask, NUMA_NO_NODE);
44 void wb_start_background_writeback(struct bdi_writeback *wb);
45 void wb_workfn(struct work_struct *work);
46 void wb_wakeup_delayed(struct bdi_writeback *wb);
48 void wb_wait_for_completion(struct wb_completion *done);
50 extern spinlock_t bdi_lock;
51 extern struct list_head bdi_list;
53 extern struct workqueue_struct *bdi_wq;
54 extern struct workqueue_struct *bdi_async_bio_wq;
56 static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
58 return test_bit(WB_has_dirty_io, &wb->state);
61 static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
64 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
65 * any dirty wbs. See wb_update_write_bandwidth().
67 return atomic_long_read(&bdi->tot_write_bandwidth);
70 static inline void __add_wb_stat(struct bdi_writeback *wb,
71 enum wb_stat_item item, s64 amount)
73 percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);
76 static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
78 __add_wb_stat(wb, item, 1);
81 static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
83 __add_wb_stat(wb, item, -1);
86 static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
88 return percpu_counter_read_positive(&wb->stat[item]);
91 static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
93 return percpu_counter_sum_positive(&wb->stat[item]);
96 extern void wb_writeout_inc(struct bdi_writeback *wb);
99 * maximal error of a stat counter.
101 static inline unsigned long wb_stat_error(void)
104 return nr_cpu_ids * WB_STAT_BATCH;
110 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
111 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
114 * Flags in backing_dev_info::capability
116 * The first three flags control whether dirty pages will contribute to the
117 * VM's accounting and whether writepages() should be called for dirty pages
118 * (something that would not, for example, be appropriate for ramfs)
120 * WARNING: these flags are closely related and should not normally be
121 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
122 * three flags into a single convenience macro.
124 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
125 * BDI_CAP_NO_WRITEBACK: Don't write pages back
126 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
127 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
129 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
130 * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
133 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
134 #define BDI_CAP_NO_WRITEBACK 0x00000002
135 #define BDI_CAP_NO_ACCT_WB 0x00000004
136 #define BDI_CAP_STABLE_WRITES 0x00000008
137 #define BDI_CAP_STRICTLIMIT 0x00000010
138 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
139 #define BDI_CAP_SYNCHRONOUS_IO 0x00000040
141 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
142 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
144 extern struct backing_dev_info noop_backing_dev_info;
147 * writeback_in_progress - determine whether there is writeback in progress
148 * @wb: bdi_writeback of interest
150 * Determine whether there is writeback waiting to be handled against a
153 static inline bool writeback_in_progress(struct bdi_writeback *wb)
155 return test_bit(WB_writeback_running, &wb->state);
158 static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
160 struct super_block *sb;
163 return &noop_backing_dev_info;
167 if (sb_is_blkdev_sb(sb))
168 return I_BDEV(inode)->bd_bdi;
173 static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
175 struct backing_dev_info *bdi = wb->bdi;
177 if (bdi->congested_fn)
178 return bdi->congested_fn(bdi->congested_data, cong_bits);
179 return wb->congested->state & cong_bits;
182 long congestion_wait(int sync, long timeout);
183 long wait_iff_congested(int sync, long timeout);
185 static inline bool bdi_cap_synchronous_io(struct backing_dev_info *bdi)
187 return bdi->capabilities & BDI_CAP_SYNCHRONOUS_IO;
190 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
192 return bdi->capabilities & BDI_CAP_STABLE_WRITES;
195 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
197 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
200 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
202 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
205 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
207 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
208 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
209 BDI_CAP_NO_WRITEBACK));
212 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
214 return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
217 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
219 return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
222 static inline int bdi_sched_wait(void *word)
228 #ifdef CONFIG_CGROUP_WRITEBACK
230 struct bdi_writeback_congested *
231 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
232 void wb_congested_put(struct bdi_writeback_congested *congested);
233 struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
234 struct cgroup_subsys_state *memcg_css);
235 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
236 struct cgroup_subsys_state *memcg_css,
238 void wb_memcg_offline(struct mem_cgroup *memcg);
239 void wb_blkcg_offline(struct blkcg *blkcg);
240 int inode_congested(struct inode *inode, int cong_bits);
243 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
244 * @inode: inode of interest
246 * cgroup writeback requires support from both the bdi and filesystem.
247 * Also, both memcg and iocg have to be on the default hierarchy. Test
248 * whether all conditions are met.
250 * Note that the test result may change dynamically on the same inode
251 * depending on how memcg and iocg are configured.
253 static inline bool inode_cgwb_enabled(struct inode *inode)
255 struct backing_dev_info *bdi = inode_to_bdi(inode);
257 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
258 cgroup_subsys_on_dfl(io_cgrp_subsys) &&
259 bdi_cap_account_dirty(bdi) &&
260 (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
261 (inode->i_sb->s_iflags & SB_I_CGROUPWB);
265 * wb_find_current - find wb for %current on a bdi
266 * @bdi: bdi of interest
268 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
269 * Must be called under rcu_read_lock() which protects the returend wb.
272 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
274 struct cgroup_subsys_state *memcg_css;
275 struct bdi_writeback *wb;
277 memcg_css = task_css(current, memory_cgrp_id);
278 if (!memcg_css->parent)
281 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
284 * %current's blkcg equals the effective blkcg of its memcg. No
285 * need to use the relatively expensive cgroup_get_e_css().
287 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
293 * wb_get_create_current - get or create wb for %current on a bdi
294 * @bdi: bdi of interest
295 * @gfp: allocation mask
297 * Equivalent to wb_get_create() on %current's memcg. This function is
298 * called from a relatively hot path and optimizes the common cases using
301 static inline struct bdi_writeback *
302 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
304 struct bdi_writeback *wb;
307 wb = wb_find_current(bdi);
308 if (wb && unlikely(!wb_tryget(wb)))
313 struct cgroup_subsys_state *memcg_css;
315 memcg_css = task_get_css(current, memory_cgrp_id);
316 wb = wb_get_create(bdi, memcg_css, gfp);
323 * inode_to_wb_is_valid - test whether an inode has a wb associated
324 * @inode: inode of interest
326 * Returns %true if @inode has a wb associated. May be called without any
329 static inline bool inode_to_wb_is_valid(struct inode *inode)
335 * inode_to_wb - determine the wb of an inode
336 * @inode: inode of interest
338 * Returns the wb @inode is currently associated with. The caller must be
339 * holding either @inode->i_lock, the i_pages lock, or the
340 * associated wb's list_lock.
342 static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
344 #ifdef CONFIG_LOCKDEP
345 WARN_ON_ONCE(debug_locks &&
346 (!lockdep_is_held(&inode->i_lock) &&
347 !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&
348 !lockdep_is_held(&inode->i_wb->list_lock)));
354 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
355 * @inode: target inode
356 * @cookie: output param, to be passed to the end function
358 * The caller wants to access the wb associated with @inode but isn't
359 * holding inode->i_lock, the i_pages lock or wb->list_lock. This
360 * function determines the wb associated with @inode and ensures that the
361 * association doesn't change until the transaction is finished with
362 * unlocked_inode_to_wb_end().
364 * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and
365 * can't sleep during the transaction. IRQs may or may not be disabled on
368 static inline struct bdi_writeback *
369 unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
374 * Paired with store_release in inode_switch_wbs_work_fn() and
375 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
377 cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
379 if (unlikely(cookie->locked))
380 xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);
383 * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages
384 * lock. inode_to_wb() will bark. Deref directly.
390 * unlocked_inode_to_wb_end - end inode wb access transaction
391 * @inode: target inode
392 * @cookie: @cookie from unlocked_inode_to_wb_begin()
394 static inline void unlocked_inode_to_wb_end(struct inode *inode,
395 struct wb_lock_cookie *cookie)
397 if (unlikely(cookie->locked))
398 xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags);
403 #else /* CONFIG_CGROUP_WRITEBACK */
405 static inline bool inode_cgwb_enabled(struct inode *inode)
410 static inline struct bdi_writeback_congested *
411 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
413 refcount_inc(&bdi->wb_congested->refcnt);
414 return bdi->wb_congested;
417 static inline void wb_congested_put(struct bdi_writeback_congested *congested)
419 if (refcount_dec_and_test(&congested->refcnt))
423 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
428 static inline struct bdi_writeback *
429 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
434 static inline bool inode_to_wb_is_valid(struct inode *inode)
439 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
441 return &inode_to_bdi(inode)->wb;
444 static inline struct bdi_writeback *
445 unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
447 return inode_to_wb(inode);
450 static inline void unlocked_inode_to_wb_end(struct inode *inode,
451 struct wb_lock_cookie *cookie)
455 static inline void wb_memcg_offline(struct mem_cgroup *memcg)
459 static inline void wb_blkcg_offline(struct blkcg *blkcg)
463 static inline int inode_congested(struct inode *inode, int cong_bits)
465 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
468 #endif /* CONFIG_CGROUP_WRITEBACK */
470 static inline int inode_read_congested(struct inode *inode)
472 return inode_congested(inode, 1 << WB_sync_congested);
475 static inline int inode_write_congested(struct inode *inode)
477 return inode_congested(inode, 1 << WB_async_congested);
480 static inline int inode_rw_congested(struct inode *inode)
482 return inode_congested(inode, (1 << WB_sync_congested) |
483 (1 << WB_async_congested));
486 static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
488 return wb_congested(&bdi->wb, cong_bits);
491 static inline int bdi_read_congested(struct backing_dev_info *bdi)
493 return bdi_congested(bdi, 1 << WB_sync_congested);
496 static inline int bdi_write_congested(struct backing_dev_info *bdi)
498 return bdi_congested(bdi, 1 << WB_async_congested);
501 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
503 return bdi_congested(bdi, (1 << WB_sync_congested) |
504 (1 << WB_async_congested));
507 #endif /* _LINUX_BACKING_DEV_H */