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, struct device *parent,
30 const char *fmt, ...);
31 int bdi_register_va(struct backing_dev_info *bdi, struct device *parent,
32 const char *fmt, va_list args);
33 int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
34 void bdi_unregister(struct backing_dev_info *bdi);
36 struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
37 static inline struct backing_dev_info *bdi_alloc(gfp_t gfp_mask)
39 return bdi_alloc_node(gfp_mask, NUMA_NO_NODE);
42 void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
43 bool range_cyclic, enum wb_reason reason);
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 extern spinlock_t bdi_lock;
49 extern struct list_head bdi_list;
51 extern struct workqueue_struct *bdi_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(&wb->stat[item], amount, WB_STAT_BATCH);
73 static inline void __inc_wb_stat(struct bdi_writeback *wb,
74 enum wb_stat_item item)
76 __add_wb_stat(wb, item, 1);
79 static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
83 local_irq_save(flags);
84 __inc_wb_stat(wb, item);
85 local_irq_restore(flags);
88 static inline void __dec_wb_stat(struct bdi_writeback *wb,
89 enum wb_stat_item item)
91 __add_wb_stat(wb, item, -1);
94 static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
98 local_irq_save(flags);
99 __dec_wb_stat(wb, item);
100 local_irq_restore(flags);
103 static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
105 return percpu_counter_read_positive(&wb->stat[item]);
108 static inline s64 __wb_stat_sum(struct bdi_writeback *wb,
109 enum wb_stat_item item)
111 return percpu_counter_sum_positive(&wb->stat[item]);
114 static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
119 local_irq_save(flags);
120 sum = __wb_stat_sum(wb, item);
121 local_irq_restore(flags);
126 extern void wb_writeout_inc(struct bdi_writeback *wb);
129 * maximal error of a stat counter.
131 static inline unsigned long wb_stat_error(struct bdi_writeback *wb)
134 return nr_cpu_ids * WB_STAT_BATCH;
140 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
141 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
144 * Flags in backing_dev_info::capability
146 * The first three flags control whether dirty pages will contribute to the
147 * VM's accounting and whether writepages() should be called for dirty pages
148 * (something that would not, for example, be appropriate for ramfs)
150 * WARNING: these flags are closely related and should not normally be
151 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
152 * three flags into a single convenience macro.
154 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
155 * BDI_CAP_NO_WRITEBACK: Don't write pages back
156 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
157 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
159 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
161 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
162 #define BDI_CAP_NO_WRITEBACK 0x00000002
163 #define BDI_CAP_NO_ACCT_WB 0x00000004
164 #define BDI_CAP_STABLE_WRITES 0x00000008
165 #define BDI_CAP_STRICTLIMIT 0x00000010
166 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
168 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
169 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
171 extern struct backing_dev_info noop_backing_dev_info;
174 * writeback_in_progress - determine whether there is writeback in progress
175 * @wb: bdi_writeback of interest
177 * Determine whether there is writeback waiting to be handled against a
180 static inline bool writeback_in_progress(struct bdi_writeback *wb)
182 return test_bit(WB_writeback_running, &wb->state);
185 static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
187 struct super_block *sb;
190 return &noop_backing_dev_info;
194 if (sb_is_blkdev_sb(sb))
195 return I_BDEV(inode)->bd_bdi;
200 static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
202 struct backing_dev_info *bdi = wb->bdi;
204 if (bdi->congested_fn)
205 return bdi->congested_fn(bdi->congested_data, cong_bits);
206 return wb->congested->state & cong_bits;
209 long congestion_wait(int sync, long timeout);
210 long wait_iff_congested(struct pglist_data *pgdat, int sync, long timeout);
211 int pdflush_proc_obsolete(struct ctl_table *table, int write,
212 void __user *buffer, size_t *lenp, loff_t *ppos);
214 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
216 return bdi->capabilities & BDI_CAP_STABLE_WRITES;
219 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
221 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
224 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
226 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
229 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
231 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
232 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
233 BDI_CAP_NO_WRITEBACK));
236 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
238 return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
241 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
243 return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
246 static inline int bdi_sched_wait(void *word)
252 #ifdef CONFIG_CGROUP_WRITEBACK
254 struct bdi_writeback_congested *
255 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
256 void wb_congested_put(struct bdi_writeback_congested *congested);
257 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
258 struct cgroup_subsys_state *memcg_css,
260 void wb_memcg_offline(struct mem_cgroup *memcg);
261 void wb_blkcg_offline(struct blkcg *blkcg);
262 int inode_congested(struct inode *inode, int cong_bits);
265 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
266 * @inode: inode of interest
268 * cgroup writeback requires support from both the bdi and filesystem.
269 * Also, both memcg and iocg have to be on the default hierarchy. Test
270 * whether all conditions are met.
272 * Note that the test result may change dynamically on the same inode
273 * depending on how memcg and iocg are configured.
275 static inline bool inode_cgwb_enabled(struct inode *inode)
277 struct backing_dev_info *bdi = inode_to_bdi(inode);
279 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
280 cgroup_subsys_on_dfl(io_cgrp_subsys) &&
281 bdi_cap_account_dirty(bdi) &&
282 (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
283 (inode->i_sb->s_iflags & SB_I_CGROUPWB);
287 * wb_find_current - find wb for %current on a bdi
288 * @bdi: bdi of interest
290 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
291 * Must be called under rcu_read_lock() which protects the returend wb.
294 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
296 struct cgroup_subsys_state *memcg_css;
297 struct bdi_writeback *wb;
299 memcg_css = task_css(current, memory_cgrp_id);
300 if (!memcg_css->parent)
303 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
306 * %current's blkcg equals the effective blkcg of its memcg. No
307 * need to use the relatively expensive cgroup_get_e_css().
309 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
315 * wb_get_create_current - get or create wb for %current on a bdi
316 * @bdi: bdi of interest
317 * @gfp: allocation mask
319 * Equivalent to wb_get_create() on %current's memcg. This function is
320 * called from a relatively hot path and optimizes the common cases using
323 static inline struct bdi_writeback *
324 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
326 struct bdi_writeback *wb;
329 wb = wb_find_current(bdi);
330 if (wb && unlikely(!wb_tryget(wb)))
335 struct cgroup_subsys_state *memcg_css;
337 memcg_css = task_get_css(current, memory_cgrp_id);
338 wb = wb_get_create(bdi, memcg_css, gfp);
345 * inode_to_wb_is_valid - test whether an inode has a wb associated
346 * @inode: inode of interest
348 * Returns %true if @inode has a wb associated. May be called without any
351 static inline bool inode_to_wb_is_valid(struct inode *inode)
357 * inode_to_wb - determine the wb of an inode
358 * @inode: inode of interest
360 * Returns the wb @inode is currently associated with. The caller must be
361 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
362 * associated wb's list_lock.
364 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
366 #ifdef CONFIG_LOCKDEP
367 WARN_ON_ONCE(debug_locks &&
368 (!lockdep_is_held(&inode->i_lock) &&
369 !lockdep_is_held(&inode->i_mapping->tree_lock) &&
370 !lockdep_is_held(&inode->i_wb->list_lock)));
376 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
377 * @inode: target inode
378 * @lockedp: temp bool output param, to be passed to the end function
380 * The caller wants to access the wb associated with @inode but isn't
381 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
382 * function determines the wb associated with @inode and ensures that the
383 * association doesn't change until the transaction is finished with
384 * unlocked_inode_to_wb_end().
386 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
387 * afterwards and can't sleep during transaction. IRQ may or may not be
388 * disabled on return.
390 static inline struct bdi_writeback *
391 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
396 * Paired with store_release in inode_switch_wb_work_fn() and
397 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
399 *lockedp = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
401 if (unlikely(*lockedp))
402 spin_lock_irq(&inode->i_mapping->tree_lock);
405 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
406 * inode_to_wb() will bark. Deref directly.
412 * unlocked_inode_to_wb_end - end inode wb access transaction
413 * @inode: target inode
414 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
416 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
418 if (unlikely(locked))
419 spin_unlock_irq(&inode->i_mapping->tree_lock);
424 #else /* CONFIG_CGROUP_WRITEBACK */
426 static inline bool inode_cgwb_enabled(struct inode *inode)
431 static inline struct bdi_writeback_congested *
432 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
434 atomic_inc(&bdi->wb_congested->refcnt);
435 return bdi->wb_congested;
438 static inline void wb_congested_put(struct bdi_writeback_congested *congested)
440 if (atomic_dec_and_test(&congested->refcnt))
444 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
449 static inline struct bdi_writeback *
450 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
455 static inline bool inode_to_wb_is_valid(struct inode *inode)
460 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
462 return &inode_to_bdi(inode)->wb;
465 static inline struct bdi_writeback *
466 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
468 return inode_to_wb(inode);
471 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
475 static inline void wb_memcg_offline(struct mem_cgroup *memcg)
479 static inline void wb_blkcg_offline(struct blkcg *blkcg)
483 static inline int inode_congested(struct inode *inode, int cong_bits)
485 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
488 #endif /* CONFIG_CGROUP_WRITEBACK */
490 static inline int inode_read_congested(struct inode *inode)
492 return inode_congested(inode, 1 << WB_sync_congested);
495 static inline int inode_write_congested(struct inode *inode)
497 return inode_congested(inode, 1 << WB_async_congested);
500 static inline int inode_rw_congested(struct inode *inode)
502 return inode_congested(inode, (1 << WB_sync_congested) |
503 (1 << WB_async_congested));
506 static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
508 return wb_congested(&bdi->wb, cong_bits);
511 static inline int bdi_read_congested(struct backing_dev_info *bdi)
513 return bdi_congested(bdi, 1 << WB_sync_congested);
516 static inline int bdi_write_congested(struct backing_dev_info *bdi)
518 return bdi_congested(bdi, 1 << WB_async_congested);
521 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
523 return bdi_congested(bdi, (1 << WB_sync_congested) |
524 (1 << WB_async_congested));
527 #endif /* _LINUX_BACKING_DEV_H */