Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
[cris-mirror.git] / include / linux / backing-dev.h
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1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * include/linux/backing-dev.h
5 * low-level device information and state which is propagated up through
6 * to high-level code.
7 */
9 #ifndef _LINUX_BACKING_DEV_H
10 #define _LINUX_BACKING_DEV_H
12 #include <linux/kernel.h>
13 #include <linux/fs.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);
24 return bdi;
27 void bdi_put(struct backing_dev_info *bdi);
29 __printf(2, 3)
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,
32 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_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(void)
98 #ifdef CONFIG_SMP
99 return nr_cpu_ids * WB_STAT_BATCH;
100 #else
101 return 1;
102 #endif
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.
125 * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
126 * inefficient.
128 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
129 #define BDI_CAP_NO_WRITEBACK 0x00000002
130 #define BDI_CAP_NO_ACCT_WB 0x00000004
131 #define BDI_CAP_STABLE_WRITES 0x00000008
132 #define BDI_CAP_STRICTLIMIT 0x00000010
133 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
134 #define BDI_CAP_SYNCHRONOUS_IO 0x00000040
136 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
137 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
139 extern struct backing_dev_info noop_backing_dev_info;
142 * writeback_in_progress - determine whether there is writeback in progress
143 * @wb: bdi_writeback of interest
145 * Determine whether there is writeback waiting to be handled against a
146 * bdi_writeback.
148 static inline bool writeback_in_progress(struct bdi_writeback *wb)
150 return test_bit(WB_writeback_running, &wb->state);
153 static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
155 struct super_block *sb;
157 if (!inode)
158 return &noop_backing_dev_info;
160 sb = inode->i_sb;
161 #ifdef CONFIG_BLOCK
162 if (sb_is_blkdev_sb(sb))
163 return I_BDEV(inode)->bd_bdi;
164 #endif
165 return sb->s_bdi;
168 static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
170 struct backing_dev_info *bdi = wb->bdi;
172 if (bdi->congested_fn)
173 return bdi->congested_fn(bdi->congested_data, cong_bits);
174 return wb->congested->state & cong_bits;
177 long congestion_wait(int sync, long timeout);
178 long wait_iff_congested(struct pglist_data *pgdat, int sync, long timeout);
180 static inline bool bdi_cap_synchronous_io(struct backing_dev_info *bdi)
182 return bdi->capabilities & BDI_CAP_SYNCHRONOUS_IO;
185 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
187 return bdi->capabilities & BDI_CAP_STABLE_WRITES;
190 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
192 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
195 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
197 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
200 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
202 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
203 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
204 BDI_CAP_NO_WRITEBACK));
207 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
209 return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
212 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
214 return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
217 static inline int bdi_sched_wait(void *word)
219 schedule();
220 return 0;
223 #ifdef CONFIG_CGROUP_WRITEBACK
225 struct bdi_writeback_congested *
226 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
227 void wb_congested_put(struct bdi_writeback_congested *congested);
228 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
229 struct cgroup_subsys_state *memcg_css,
230 gfp_t gfp);
231 void wb_memcg_offline(struct mem_cgroup *memcg);
232 void wb_blkcg_offline(struct blkcg *blkcg);
233 int inode_congested(struct inode *inode, int cong_bits);
236 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
237 * @inode: inode of interest
239 * cgroup writeback requires support from both the bdi and filesystem.
240 * Also, both memcg and iocg have to be on the default hierarchy. Test
241 * whether all conditions are met.
243 * Note that the test result may change dynamically on the same inode
244 * depending on how memcg and iocg are configured.
246 static inline bool inode_cgwb_enabled(struct inode *inode)
248 struct backing_dev_info *bdi = inode_to_bdi(inode);
250 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
251 cgroup_subsys_on_dfl(io_cgrp_subsys) &&
252 bdi_cap_account_dirty(bdi) &&
253 (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
254 (inode->i_sb->s_iflags & SB_I_CGROUPWB);
258 * wb_find_current - find wb for %current on a bdi
259 * @bdi: bdi of interest
261 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
262 * Must be called under rcu_read_lock() which protects the returend wb.
263 * NULL if not found.
265 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
267 struct cgroup_subsys_state *memcg_css;
268 struct bdi_writeback *wb;
270 memcg_css = task_css(current, memory_cgrp_id);
271 if (!memcg_css->parent)
272 return &bdi->wb;
274 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
277 * %current's blkcg equals the effective blkcg of its memcg. No
278 * need to use the relatively expensive cgroup_get_e_css().
280 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
281 return wb;
282 return NULL;
286 * wb_get_create_current - get or create wb for %current on a bdi
287 * @bdi: bdi of interest
288 * @gfp: allocation mask
290 * Equivalent to wb_get_create() on %current's memcg. This function is
291 * called from a relatively hot path and optimizes the common cases using
292 * wb_find_current().
294 static inline struct bdi_writeback *
295 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
297 struct bdi_writeback *wb;
299 rcu_read_lock();
300 wb = wb_find_current(bdi);
301 if (wb && unlikely(!wb_tryget(wb)))
302 wb = NULL;
303 rcu_read_unlock();
305 if (unlikely(!wb)) {
306 struct cgroup_subsys_state *memcg_css;
308 memcg_css = task_get_css(current, memory_cgrp_id);
309 wb = wb_get_create(bdi, memcg_css, gfp);
310 css_put(memcg_css);
312 return wb;
316 * inode_to_wb_is_valid - test whether an inode has a wb associated
317 * @inode: inode of interest
319 * Returns %true if @inode has a wb associated. May be called without any
320 * locking.
322 static inline bool inode_to_wb_is_valid(struct inode *inode)
324 return inode->i_wb;
328 * inode_to_wb - determine the wb of an inode
329 * @inode: inode of interest
331 * Returns the wb @inode is currently associated with. The caller must be
332 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
333 * associated wb's list_lock.
335 static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
337 #ifdef CONFIG_LOCKDEP
338 WARN_ON_ONCE(debug_locks &&
339 (!lockdep_is_held(&inode->i_lock) &&
340 !lockdep_is_held(&inode->i_mapping->tree_lock) &&
341 !lockdep_is_held(&inode->i_wb->list_lock)));
342 #endif
343 return inode->i_wb;
347 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
348 * @inode: target inode
349 * @lockedp: temp bool output param, to be passed to the end function
351 * The caller wants to access the wb associated with @inode but isn't
352 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
353 * function determines the wb associated with @inode and ensures that the
354 * association doesn't change until the transaction is finished with
355 * unlocked_inode_to_wb_end().
357 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
358 * afterwards and can't sleep during transaction. IRQ may or may not be
359 * disabled on return.
361 static inline struct bdi_writeback *
362 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
364 rcu_read_lock();
367 * Paired with store_release in inode_switch_wb_work_fn() and
368 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
370 *lockedp = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
372 if (unlikely(*lockedp))
373 spin_lock_irq(&inode->i_mapping->tree_lock);
376 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
377 * inode_to_wb() will bark. Deref directly.
379 return inode->i_wb;
383 * unlocked_inode_to_wb_end - end inode wb access transaction
384 * @inode: target inode
385 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
387 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
389 if (unlikely(locked))
390 spin_unlock_irq(&inode->i_mapping->tree_lock);
392 rcu_read_unlock();
395 #else /* CONFIG_CGROUP_WRITEBACK */
397 static inline bool inode_cgwb_enabled(struct inode *inode)
399 return false;
402 static inline struct bdi_writeback_congested *
403 wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
405 atomic_inc(&bdi->wb_congested->refcnt);
406 return bdi->wb_congested;
409 static inline void wb_congested_put(struct bdi_writeback_congested *congested)
411 if (atomic_dec_and_test(&congested->refcnt))
412 kfree(congested);
415 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
417 return &bdi->wb;
420 static inline struct bdi_writeback *
421 wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
423 return &bdi->wb;
426 static inline bool inode_to_wb_is_valid(struct inode *inode)
428 return true;
431 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
433 return &inode_to_bdi(inode)->wb;
436 static inline struct bdi_writeback *
437 unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
439 return inode_to_wb(inode);
442 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
446 static inline void wb_memcg_offline(struct mem_cgroup *memcg)
450 static inline void wb_blkcg_offline(struct blkcg *blkcg)
454 static inline int inode_congested(struct inode *inode, int cong_bits)
456 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
459 #endif /* CONFIG_CGROUP_WRITEBACK */
461 static inline int inode_read_congested(struct inode *inode)
463 return inode_congested(inode, 1 << WB_sync_congested);
466 static inline int inode_write_congested(struct inode *inode)
468 return inode_congested(inode, 1 << WB_async_congested);
471 static inline int inode_rw_congested(struct inode *inode)
473 return inode_congested(inode, (1 << WB_sync_congested) |
474 (1 << WB_async_congested));
477 static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
479 return wb_congested(&bdi->wb, cong_bits);
482 static inline int bdi_read_congested(struct backing_dev_info *bdi)
484 return bdi_congested(bdi, 1 << WB_sync_congested);
487 static inline int bdi_write_congested(struct backing_dev_info *bdi)
489 return bdi_congested(bdi, 1 << WB_async_congested);
492 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
494 return bdi_congested(bdi, (1 << WB_sync_congested) |
495 (1 << WB_async_congested));
498 #endif /* _LINUX_BACKING_DEV_H */