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 static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
22 kref_get(&bdi->refcnt);
26 void bdi_put(struct backing_dev_info *bdi);
29 int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
30 int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
32 int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
33 void bdi_unregister(struct backing_dev_info *bdi);
35 struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
36 static inline struct backing_dev_info *bdi_alloc(gfp_t gfp_mask)
38 return bdi_alloc_node(gfp_mask, NUMA_NO_NODE);
41 void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
42 bool range_cyclic, enum wb_reason reason);
43 void wb_start_background_writeback(struct bdi_writeback *wb);
44 void wb_workfn(struct work_struct *work);
45 void wb_wakeup_delayed(struct bdi_writeback *wb);
47 extern spinlock_t bdi_lock;
48 extern struct list_head bdi_list;
50 extern struct workqueue_struct *bdi_wq;
52 static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
54 return test_bit(WB_has_dirty_io, &wb->state);
57 static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
60 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
61 * any dirty wbs. See wb_update_write_bandwidth().
63 return atomic_long_read(&bdi->tot_write_bandwidth);
66 static inline void __add_wb_stat(struct bdi_writeback *wb,
67 enum wb_stat_item item, s64 amount)
69 __percpu_counter_add(&wb->stat[item], amount, WB_STAT_BATCH);
72 static inline void __inc_wb_stat(struct bdi_writeback *wb,
73 enum wb_stat_item item)
75 __add_wb_stat(wb, item, 1);
78 static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
82 local_irq_save(flags);
83 __inc_wb_stat(wb, item);
84 local_irq_restore(flags);
87 static inline void __dec_wb_stat(struct bdi_writeback *wb,
88 enum wb_stat_item item)
90 __add_wb_stat(wb, item, -1);
93 static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
97 local_irq_save(flags);
98 __dec_wb_stat(wb, item);
99 local_irq_restore(flags);
102 static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
104 return percpu_counter_read_positive(&wb->stat[item]);
107 static inline s64 __wb_stat_sum(struct bdi_writeback *wb,
108 enum wb_stat_item item)
110 return percpu_counter_sum_positive(&wb->stat[item]);
113 static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
118 local_irq_save(flags);
119 sum = __wb_stat_sum(wb, item);
120 local_irq_restore(flags);
125 extern void wb_writeout_inc(struct bdi_writeback *wb);
128 * maximal error of a stat counter.
130 static inline unsigned long wb_stat_error(struct bdi_writeback *wb)
133 return nr_cpu_ids * WB_STAT_BATCH;
139 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
140 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
143 * Flags in backing_dev_info::capability
145 * The first three flags control whether dirty pages will contribute to the
146 * VM's accounting and whether writepages() should be called for dirty pages
147 * (something that would not, for example, be appropriate for ramfs)
149 * WARNING: these flags are closely related and should not normally be
150 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
151 * three flags into a single convenience macro.
153 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
154 * BDI_CAP_NO_WRITEBACK: Don't write pages back
155 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
156 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
158 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
160 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
161 #define BDI_CAP_NO_WRITEBACK 0x00000002
162 #define BDI_CAP_NO_ACCT_WB 0x00000004
163 #define BDI_CAP_STABLE_WRITES 0x00000008
164 #define BDI_CAP_STRICTLIMIT 0x00000010
165 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
167 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
168 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
170 extern struct backing_dev_info noop_backing_dev_info;
173 * writeback_in_progress - determine whether there is writeback in progress
174 * @wb: bdi_writeback of interest
176 * Determine whether there is writeback waiting to be handled against a
179 static inline bool writeback_in_progress(struct bdi_writeback *wb)
181 return test_bit(WB_writeback_running, &wb->state);
184 static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
186 struct super_block *sb;
189 return &noop_backing_dev_info;
193 if (sb_is_blkdev_sb(sb))
194 return I_BDEV(inode)->bd_bdi;
199 static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
201 struct backing_dev_info *bdi = wb->bdi;
203 if (bdi->congested_fn)
204 return bdi->congested_fn(bdi->congested_data, cong_bits);
205 return wb->congested->state & cong_bits;
208 long congestion_wait(int sync, long timeout);
209 long wait_iff_congested(struct pglist_data *pgdat, int sync, long timeout);
210 int pdflush_proc_obsolete(struct ctl_table *table, int write,
211 void __user *buffer, size_t *lenp, loff_t *ppos);
213 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
215 return bdi->capabilities & BDI_CAP_STABLE_WRITES;
218 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
220 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
223 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
225 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
228 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
230 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
231 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
232 BDI_CAP_NO_WRITEBACK));
235 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
237 return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
240 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
242 return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
245 static inline int bdi_sched_wait(void *word)
251 #ifdef CONFIG_CGROUP_WRITEBACK
253 struct bdi_writeback_congested *
254 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
255 void wb_congested_put(struct bdi_writeback_congested *congested);
256 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
257 struct cgroup_subsys_state *memcg_css,
259 void wb_memcg_offline(struct mem_cgroup *memcg);
260 void wb_blkcg_offline(struct blkcg *blkcg);
261 int inode_congested(struct inode *inode, int cong_bits);
264 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
265 * @inode: inode of interest
267 * cgroup writeback requires support from both the bdi and filesystem.
268 * Also, both memcg and iocg have to be on the default hierarchy. Test
269 * whether all conditions are met.
271 * Note that the test result may change dynamically on the same inode
272 * depending on how memcg and iocg are configured.
274 static inline bool inode_cgwb_enabled(struct inode *inode)
276 struct backing_dev_info *bdi = inode_to_bdi(inode);
278 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
279 cgroup_subsys_on_dfl(io_cgrp_subsys) &&
280 bdi_cap_account_dirty(bdi) &&
281 (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
282 (inode->i_sb->s_iflags & SB_I_CGROUPWB);
286 * wb_find_current - find wb for %current on a bdi
287 * @bdi: bdi of interest
289 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
290 * Must be called under rcu_read_lock() which protects the returend wb.
293 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
295 struct cgroup_subsys_state *memcg_css;
296 struct bdi_writeback *wb;
298 memcg_css = task_css(current, memory_cgrp_id);
299 if (!memcg_css->parent)
302 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
305 * %current's blkcg equals the effective blkcg of its memcg. No
306 * need to use the relatively expensive cgroup_get_e_css().
308 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
314 * wb_get_create_current - get or create wb for %current on a bdi
315 * @bdi: bdi of interest
316 * @gfp: allocation mask
318 * Equivalent to wb_get_create() on %current's memcg. This function is
319 * called from a relatively hot path and optimizes the common cases using
322 static inline struct bdi_writeback *
323 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
325 struct bdi_writeback *wb;
328 wb = wb_find_current(bdi);
329 if (wb && unlikely(!wb_tryget(wb)))
334 struct cgroup_subsys_state *memcg_css;
336 memcg_css = task_get_css(current, memory_cgrp_id);
337 wb = wb_get_create(bdi, memcg_css, gfp);
344 * inode_to_wb_is_valid - test whether an inode has a wb associated
345 * @inode: inode of interest
347 * Returns %true if @inode has a wb associated. May be called without any
350 static inline bool inode_to_wb_is_valid(struct inode *inode)
356 * inode_to_wb - determine the wb of an inode
357 * @inode: inode of interest
359 * Returns the wb @inode is currently associated with. The caller must be
360 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
361 * associated wb's list_lock.
363 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
365 #ifdef CONFIG_LOCKDEP
366 WARN_ON_ONCE(debug_locks &&
367 (!lockdep_is_held(&inode->i_lock) &&
368 !lockdep_is_held(&inode->i_mapping->tree_lock) &&
369 !lockdep_is_held(&inode->i_wb->list_lock)));
375 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
376 * @inode: target inode
377 * @lockedp: temp bool output param, to be passed to the end function
379 * The caller wants to access the wb associated with @inode but isn't
380 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
381 * function determines the wb associated with @inode and ensures that the
382 * association doesn't change until the transaction is finished with
383 * unlocked_inode_to_wb_end().
385 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
386 * afterwards and can't sleep during transaction. IRQ may or may not be
387 * disabled on return.
389 static inline struct bdi_writeback *
390 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
395 * Paired with store_release in inode_switch_wb_work_fn() and
396 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
398 *lockedp = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
400 if (unlikely(*lockedp))
401 spin_lock_irq(&inode->i_mapping->tree_lock);
404 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
405 * inode_to_wb() will bark. Deref directly.
411 * unlocked_inode_to_wb_end - end inode wb access transaction
412 * @inode: target inode
413 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
415 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
417 if (unlikely(locked))
418 spin_unlock_irq(&inode->i_mapping->tree_lock);
423 #else /* CONFIG_CGROUP_WRITEBACK */
425 static inline bool inode_cgwb_enabled(struct inode *inode)
430 static inline struct bdi_writeback_congested *
431 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
433 atomic_inc(&bdi->wb_congested->refcnt);
434 return bdi->wb_congested;
437 static inline void wb_congested_put(struct bdi_writeback_congested *congested)
439 if (atomic_dec_and_test(&congested->refcnt))
443 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
448 static inline struct bdi_writeback *
449 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
454 static inline bool inode_to_wb_is_valid(struct inode *inode)
459 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
461 return &inode_to_bdi(inode)->wb;
464 static inline struct bdi_writeback *
465 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
467 return inode_to_wb(inode);
470 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
474 static inline void wb_memcg_offline(struct mem_cgroup *memcg)
478 static inline void wb_blkcg_offline(struct blkcg *blkcg)
482 static inline int inode_congested(struct inode *inode, int cong_bits)
484 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
487 #endif /* CONFIG_CGROUP_WRITEBACK */
489 static inline int inode_read_congested(struct inode *inode)
491 return inode_congested(inode, 1 << WB_sync_congested);
494 static inline int inode_write_congested(struct inode *inode)
496 return inode_congested(inode, 1 << WB_async_congested);
499 static inline int inode_rw_congested(struct inode *inode)
501 return inode_congested(inode, (1 << WB_sync_congested) |
502 (1 << WB_async_congested));
505 static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
507 return wb_congested(&bdi->wb, cong_bits);
510 static inline int bdi_read_congested(struct backing_dev_info *bdi)
512 return bdi_congested(bdi, 1 << WB_sync_congested);
515 static inline int bdi_write_congested(struct backing_dev_info *bdi)
517 return bdi_congested(bdi, 1 << WB_async_congested);
520 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
522 return bdi_congested(bdi, (1 << WB_sync_congested) |
523 (1 << WB_async_congested));
526 #endif /* _LINUX_BACKING_DEV_H */