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 void bdi_put(struct backing_dev_info *bdi);
30 int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
31 int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
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_background_writeback(struct bdi_writeback *wb);
43 void wb_workfn(struct work_struct *work);
44 void wb_wakeup_delayed(struct bdi_writeback *wb);
46 extern spinlock_t bdi_lock;
47 extern struct list_head bdi_list;
49 extern struct workqueue_struct *bdi_wq;
51 static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
53 return test_bit(WB_has_dirty_io, &wb->state);
56 static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
59 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
60 * any dirty wbs. See wb_update_write_bandwidth().
62 return atomic_long_read(&bdi->tot_write_bandwidth);
65 static inline void __add_wb_stat(struct bdi_writeback *wb,
66 enum wb_stat_item item, s64 amount)
68 percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);
71 static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
73 __add_wb_stat(wb, item, 1);
76 static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
78 __add_wb_stat(wb, item, -1);
81 static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
83 return percpu_counter_read_positive(&wb->stat[item]);
86 static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
88 return percpu_counter_sum_positive(&wb->stat[item]);
91 extern void wb_writeout_inc(struct bdi_writeback *wb);
94 * maximal error of a stat counter.
96 static inline unsigned long wb_stat_error(struct bdi_writeback *wb)
99 return nr_cpu_ids * WB_STAT_BATCH;
105 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
106 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
109 * Flags in backing_dev_info::capability
111 * The first three flags control whether dirty pages will contribute to the
112 * VM's accounting and whether writepages() should be called for dirty pages
113 * (something that would not, for example, be appropriate for ramfs)
115 * WARNING: these flags are closely related and should not normally be
116 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
117 * three flags into a single convenience macro.
119 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
120 * BDI_CAP_NO_WRITEBACK: Don't write pages back
121 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
122 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
124 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
126 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
127 #define BDI_CAP_NO_WRITEBACK 0x00000002
128 #define BDI_CAP_NO_ACCT_WB 0x00000004
129 #define BDI_CAP_STABLE_WRITES 0x00000008
130 #define BDI_CAP_STRICTLIMIT 0x00000010
131 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
133 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
134 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
136 extern struct backing_dev_info noop_backing_dev_info;
139 * writeback_in_progress - determine whether there is writeback in progress
140 * @wb: bdi_writeback of interest
142 * Determine whether there is writeback waiting to be handled against a
145 static inline bool writeback_in_progress(struct bdi_writeback *wb)
147 return test_bit(WB_writeback_running, &wb->state);
150 static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
152 struct super_block *sb;
155 return &noop_backing_dev_info;
159 if (sb_is_blkdev_sb(sb))
160 return I_BDEV(inode)->bd_bdi;
165 static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
167 struct backing_dev_info *bdi = wb->bdi;
169 if (bdi->congested_fn)
170 return bdi->congested_fn(bdi->congested_data, cong_bits);
171 return wb->congested->state & cong_bits;
174 long congestion_wait(int sync, long timeout);
175 long wait_iff_congested(struct pglist_data *pgdat, int sync, long timeout);
177 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
179 return bdi->capabilities & BDI_CAP_STABLE_WRITES;
182 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
184 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
187 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
189 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
192 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
194 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
195 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
196 BDI_CAP_NO_WRITEBACK));
199 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
201 return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
204 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
206 return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
209 static inline int bdi_sched_wait(void *word)
215 #ifdef CONFIG_CGROUP_WRITEBACK
217 struct bdi_writeback_congested *
218 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
219 void wb_congested_put(struct bdi_writeback_congested *congested);
220 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
221 struct cgroup_subsys_state *memcg_css,
223 void wb_memcg_offline(struct mem_cgroup *memcg);
224 void wb_blkcg_offline(struct blkcg *blkcg);
225 int inode_congested(struct inode *inode, int cong_bits);
228 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
229 * @inode: inode of interest
231 * cgroup writeback requires support from both the bdi and filesystem.
232 * Also, both memcg and iocg have to be on the default hierarchy. Test
233 * whether all conditions are met.
235 * Note that the test result may change dynamically on the same inode
236 * depending on how memcg and iocg are configured.
238 static inline bool inode_cgwb_enabled(struct inode *inode)
240 struct backing_dev_info *bdi = inode_to_bdi(inode);
242 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
243 cgroup_subsys_on_dfl(io_cgrp_subsys) &&
244 bdi_cap_account_dirty(bdi) &&
245 (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
246 (inode->i_sb->s_iflags & SB_I_CGROUPWB);
250 * wb_find_current - find wb for %current on a bdi
251 * @bdi: bdi of interest
253 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
254 * Must be called under rcu_read_lock() which protects the returend wb.
257 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
259 struct cgroup_subsys_state *memcg_css;
260 struct bdi_writeback *wb;
262 memcg_css = task_css(current, memory_cgrp_id);
263 if (!memcg_css->parent)
266 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
269 * %current's blkcg equals the effective blkcg of its memcg. No
270 * need to use the relatively expensive cgroup_get_e_css().
272 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
278 * wb_get_create_current - get or create wb for %current on a bdi
279 * @bdi: bdi of interest
280 * @gfp: allocation mask
282 * Equivalent to wb_get_create() on %current's memcg. This function is
283 * called from a relatively hot path and optimizes the common cases using
286 static inline struct bdi_writeback *
287 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
289 struct bdi_writeback *wb;
292 wb = wb_find_current(bdi);
293 if (wb && unlikely(!wb_tryget(wb)))
298 struct cgroup_subsys_state *memcg_css;
300 memcg_css = task_get_css(current, memory_cgrp_id);
301 wb = wb_get_create(bdi, memcg_css, gfp);
308 * inode_to_wb_is_valid - test whether an inode has a wb associated
309 * @inode: inode of interest
311 * Returns %true if @inode has a wb associated. May be called without any
314 static inline bool inode_to_wb_is_valid(struct inode *inode)
320 * inode_to_wb - determine the wb of an inode
321 * @inode: inode of interest
323 * Returns the wb @inode is currently associated with. The caller must be
324 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
325 * associated wb's list_lock.
327 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
329 #ifdef CONFIG_LOCKDEP
330 WARN_ON_ONCE(debug_locks &&
331 (!lockdep_is_held(&inode->i_lock) &&
332 !lockdep_is_held(&inode->i_mapping->tree_lock) &&
333 !lockdep_is_held(&inode->i_wb->list_lock)));
339 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
340 * @inode: target inode
341 * @lockedp: temp bool output param, to be passed to the end function
343 * The caller wants to access the wb associated with @inode but isn't
344 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
345 * function determines the wb associated with @inode and ensures that the
346 * association doesn't change until the transaction is finished with
347 * unlocked_inode_to_wb_end().
349 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
350 * afterwards and can't sleep during transaction. IRQ may or may not be
351 * disabled on return.
353 static inline struct bdi_writeback *
354 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
359 * Paired with store_release in inode_switch_wb_work_fn() and
360 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
362 *lockedp = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
364 if (unlikely(*lockedp))
365 spin_lock_irq(&inode->i_mapping->tree_lock);
368 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
369 * inode_to_wb() will bark. Deref directly.
375 * unlocked_inode_to_wb_end - end inode wb access transaction
376 * @inode: target inode
377 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
379 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
381 if (unlikely(locked))
382 spin_unlock_irq(&inode->i_mapping->tree_lock);
387 #else /* CONFIG_CGROUP_WRITEBACK */
389 static inline bool inode_cgwb_enabled(struct inode *inode)
394 static inline struct bdi_writeback_congested *
395 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
397 atomic_inc(&bdi->wb_congested->refcnt);
398 return bdi->wb_congested;
401 static inline void wb_congested_put(struct bdi_writeback_congested *congested)
403 if (atomic_dec_and_test(&congested->refcnt))
407 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
412 static inline struct bdi_writeback *
413 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
418 static inline bool inode_to_wb_is_valid(struct inode *inode)
423 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
425 return &inode_to_bdi(inode)->wb;
428 static inline struct bdi_writeback *
429 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
431 return inode_to_wb(inode);
434 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
438 static inline void wb_memcg_offline(struct mem_cgroup *memcg)
442 static inline void wb_blkcg_offline(struct blkcg *blkcg)
446 static inline int inode_congested(struct inode *inode, int cong_bits)
448 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
451 #endif /* CONFIG_CGROUP_WRITEBACK */
453 static inline int inode_read_congested(struct inode *inode)
455 return inode_congested(inode, 1 << WB_sync_congested);
458 static inline int inode_write_congested(struct inode *inode)
460 return inode_congested(inode, 1 << WB_async_congested);
463 static inline int inode_rw_congested(struct inode *inode)
465 return inode_congested(inode, (1 << WB_sync_congested) |
466 (1 << WB_async_congested));
469 static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
471 return wb_congested(&bdi->wb, cong_bits);
474 static inline int bdi_read_congested(struct backing_dev_info *bdi)
476 return bdi_congested(bdi, 1 << WB_sync_congested);
479 static inline int bdi_write_congested(struct backing_dev_info *bdi)
481 return bdi_congested(bdi, 1 << WB_async_congested);
484 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
486 return bdi_congested(bdi, (1 << WB_sync_congested) |
487 (1 << WB_async_congested));
490 #endif /* _LINUX_BACKING_DEV_H */