2 * include/linux/backing-dev.h
4 * low-level device information and state which is propagated up through
8 #ifndef _LINUX_BACKING_DEV_H
9 #define _LINUX_BACKING_DEV_H
11 #include <linux/kernel.h>
13 #include <linux/sched.h>
14 #include <linux/blkdev.h>
15 #include <linux/writeback.h>
16 #include <linux/blk-cgroup.h>
17 #include <linux/backing-dev-defs.h>
18 #include <linux/slab.h>
20 int __must_check bdi_init(struct backing_dev_info *bdi);
22 static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
24 kref_get(&bdi->refcnt);
28 void bdi_put(struct backing_dev_info *bdi);
31 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
32 const char *fmt, ...);
33 int bdi_register_va(struct backing_dev_info *bdi, struct device *parent,
34 const char *fmt, va_list args);
35 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
36 int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
37 void bdi_unregister(struct backing_dev_info *bdi);
39 int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
40 void bdi_destroy(struct backing_dev_info *bdi);
41 struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
42 static inline struct backing_dev_info *bdi_alloc(gfp_t gfp_mask)
44 return bdi_alloc_node(gfp_mask, NUMA_NO_NODE);
47 void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
48 bool range_cyclic, enum wb_reason reason);
49 void wb_start_background_writeback(struct bdi_writeback *wb);
50 void wb_workfn(struct work_struct *work);
51 void wb_wakeup_delayed(struct bdi_writeback *wb);
53 extern spinlock_t bdi_lock;
54 extern struct list_head bdi_list;
56 extern struct workqueue_struct *bdi_wq;
58 static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
60 return test_bit(WB_has_dirty_io, &wb->state);
63 static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
66 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
67 * any dirty wbs. See wb_update_write_bandwidth().
69 return atomic_long_read(&bdi->tot_write_bandwidth);
72 static inline void __add_wb_stat(struct bdi_writeback *wb,
73 enum wb_stat_item item, s64 amount)
75 __percpu_counter_add(&wb->stat[item], amount, WB_STAT_BATCH);
78 static inline void __inc_wb_stat(struct bdi_writeback *wb,
79 enum wb_stat_item item)
81 __add_wb_stat(wb, item, 1);
84 static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
88 local_irq_save(flags);
89 __inc_wb_stat(wb, item);
90 local_irq_restore(flags);
93 static inline void __dec_wb_stat(struct bdi_writeback *wb,
94 enum wb_stat_item item)
96 __add_wb_stat(wb, item, -1);
99 static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
103 local_irq_save(flags);
104 __dec_wb_stat(wb, item);
105 local_irq_restore(flags);
108 static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
110 return percpu_counter_read_positive(&wb->stat[item]);
113 static inline s64 __wb_stat_sum(struct bdi_writeback *wb,
114 enum wb_stat_item item)
116 return percpu_counter_sum_positive(&wb->stat[item]);
119 static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
124 local_irq_save(flags);
125 sum = __wb_stat_sum(wb, item);
126 local_irq_restore(flags);
131 extern void wb_writeout_inc(struct bdi_writeback *wb);
134 * maximal error of a stat counter.
136 static inline unsigned long wb_stat_error(struct bdi_writeback *wb)
139 return nr_cpu_ids * WB_STAT_BATCH;
145 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
146 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
149 * Flags in backing_dev_info::capability
151 * The first three flags control whether dirty pages will contribute to the
152 * VM's accounting and whether writepages() should be called for dirty pages
153 * (something that would not, for example, be appropriate for ramfs)
155 * WARNING: these flags are closely related and should not normally be
156 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
157 * three flags into a single convenience macro.
159 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
160 * BDI_CAP_NO_WRITEBACK: Don't write pages back
161 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
162 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
164 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
166 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
167 #define BDI_CAP_NO_WRITEBACK 0x00000002
168 #define BDI_CAP_NO_ACCT_WB 0x00000004
169 #define BDI_CAP_STABLE_WRITES 0x00000008
170 #define BDI_CAP_STRICTLIMIT 0x00000010
171 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
173 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
174 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
176 extern struct backing_dev_info noop_backing_dev_info;
179 * writeback_in_progress - determine whether there is writeback in progress
180 * @wb: bdi_writeback of interest
182 * Determine whether there is writeback waiting to be handled against a
185 static inline bool writeback_in_progress(struct bdi_writeback *wb)
187 return test_bit(WB_writeback_running, &wb->state);
190 static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
192 struct super_block *sb;
195 return &noop_backing_dev_info;
199 if (sb_is_blkdev_sb(sb))
200 return I_BDEV(inode)->bd_bdi;
205 static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
207 struct backing_dev_info *bdi = wb->bdi;
209 if (bdi->congested_fn)
210 return bdi->congested_fn(bdi->congested_data, cong_bits);
211 return wb->congested->state & cong_bits;
214 long congestion_wait(int sync, long timeout);
215 long wait_iff_congested(struct pglist_data *pgdat, int sync, long timeout);
216 int pdflush_proc_obsolete(struct ctl_table *table, int write,
217 void __user *buffer, size_t *lenp, loff_t *ppos);
219 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
221 return bdi->capabilities & BDI_CAP_STABLE_WRITES;
224 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
226 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
229 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
231 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
234 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
236 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
237 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
238 BDI_CAP_NO_WRITEBACK));
241 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
243 return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
246 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
248 return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
251 static inline int bdi_sched_wait(void *word)
257 #ifdef CONFIG_CGROUP_WRITEBACK
259 struct bdi_writeback_congested *
260 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
261 void wb_congested_put(struct bdi_writeback_congested *congested);
262 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
263 struct cgroup_subsys_state *memcg_css,
265 void wb_memcg_offline(struct mem_cgroup *memcg);
266 void wb_blkcg_offline(struct blkcg *blkcg);
267 int inode_congested(struct inode *inode, int cong_bits);
270 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
271 * @inode: inode of interest
273 * cgroup writeback requires support from both the bdi and filesystem.
274 * Also, both memcg and iocg have to be on the default hierarchy. Test
275 * whether all conditions are met.
277 * Note that the test result may change dynamically on the same inode
278 * depending on how memcg and iocg are configured.
280 static inline bool inode_cgwb_enabled(struct inode *inode)
282 struct backing_dev_info *bdi = inode_to_bdi(inode);
284 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
285 cgroup_subsys_on_dfl(io_cgrp_subsys) &&
286 bdi_cap_account_dirty(bdi) &&
287 (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
288 (inode->i_sb->s_iflags & SB_I_CGROUPWB);
292 * wb_find_current - find wb for %current on a bdi
293 * @bdi: bdi of interest
295 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
296 * Must be called under rcu_read_lock() which protects the returend wb.
299 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
301 struct cgroup_subsys_state *memcg_css;
302 struct bdi_writeback *wb;
304 memcg_css = task_css(current, memory_cgrp_id);
305 if (!memcg_css->parent)
308 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
311 * %current's blkcg equals the effective blkcg of its memcg. No
312 * need to use the relatively expensive cgroup_get_e_css().
314 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
320 * wb_get_create_current - get or create wb for %current on a bdi
321 * @bdi: bdi of interest
322 * @gfp: allocation mask
324 * Equivalent to wb_get_create() on %current's memcg. This function is
325 * called from a relatively hot path and optimizes the common cases using
328 static inline struct bdi_writeback *
329 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
331 struct bdi_writeback *wb;
334 wb = wb_find_current(bdi);
335 if (wb && unlikely(!wb_tryget(wb)))
340 struct cgroup_subsys_state *memcg_css;
342 memcg_css = task_get_css(current, memory_cgrp_id);
343 wb = wb_get_create(bdi, memcg_css, gfp);
350 * inode_to_wb_is_valid - test whether an inode has a wb associated
351 * @inode: inode of interest
353 * Returns %true if @inode has a wb associated. May be called without any
356 static inline bool inode_to_wb_is_valid(struct inode *inode)
362 * inode_to_wb - determine the wb of an inode
363 * @inode: inode of interest
365 * Returns the wb @inode is currently associated with. The caller must be
366 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
367 * associated wb's list_lock.
369 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
371 #ifdef CONFIG_LOCKDEP
372 WARN_ON_ONCE(debug_locks &&
373 (!lockdep_is_held(&inode->i_lock) &&
374 !lockdep_is_held(&inode->i_mapping->tree_lock) &&
375 !lockdep_is_held(&inode->i_wb->list_lock)));
381 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
382 * @inode: target inode
383 * @lockedp: temp bool output param, to be passed to the end function
385 * The caller wants to access the wb associated with @inode but isn't
386 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
387 * function determines the wb associated with @inode and ensures that the
388 * association doesn't change until the transaction is finished with
389 * unlocked_inode_to_wb_end().
391 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
392 * afterwards and can't sleep during transaction. IRQ may or may not be
393 * disabled on return.
395 static inline struct bdi_writeback *
396 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
401 * Paired with store_release in inode_switch_wb_work_fn() and
402 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
404 *lockedp = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
406 if (unlikely(*lockedp))
407 spin_lock_irq(&inode->i_mapping->tree_lock);
410 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
411 * inode_to_wb() will bark. Deref directly.
417 * unlocked_inode_to_wb_end - end inode wb access transaction
418 * @inode: target inode
419 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
421 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
423 if (unlikely(locked))
424 spin_unlock_irq(&inode->i_mapping->tree_lock);
429 #else /* CONFIG_CGROUP_WRITEBACK */
431 static inline bool inode_cgwb_enabled(struct inode *inode)
436 static inline struct bdi_writeback_congested *
437 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
439 atomic_inc(&bdi->wb_congested->refcnt);
440 return bdi->wb_congested;
443 static inline void wb_congested_put(struct bdi_writeback_congested *congested)
445 if (atomic_dec_and_test(&congested->refcnt))
449 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
454 static inline struct bdi_writeback *
455 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
460 static inline bool inode_to_wb_is_valid(struct inode *inode)
465 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
467 return &inode_to_bdi(inode)->wb;
470 static inline struct bdi_writeback *
471 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
473 return inode_to_wb(inode);
476 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
480 static inline void wb_memcg_offline(struct mem_cgroup *memcg)
484 static inline void wb_blkcg_offline(struct blkcg *blkcg)
488 static inline int inode_congested(struct inode *inode, int cong_bits)
490 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
493 #endif /* CONFIG_CGROUP_WRITEBACK */
495 static inline int inode_read_congested(struct inode *inode)
497 return inode_congested(inode, 1 << WB_sync_congested);
500 static inline int inode_write_congested(struct inode *inode)
502 return inode_congested(inode, 1 << WB_async_congested);
505 static inline int inode_rw_congested(struct inode *inode)
507 return inode_congested(inode, (1 << WB_sync_congested) |
508 (1 << WB_async_congested));
511 static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
513 return wb_congested(&bdi->wb, cong_bits);
516 static inline int bdi_read_congested(struct backing_dev_info *bdi)
518 return bdi_congested(bdi, 1 << WB_sync_congested);
521 static inline int bdi_write_congested(struct backing_dev_info *bdi)
523 return bdi_congested(bdi, 1 << WB_async_congested);
526 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
528 return bdi_congested(bdi, (1 << WB_sync_congested) |
529 (1 << WB_async_congested));
532 #endif /* _LINUX_BACKING_DEV_H */