summaryrefslogtreecommitdiffstats
path: root/include/linux/backing-dev.h
blob: e6cbb915ee56a2572e649460be1e484446fcfd2d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * include/linux/backing-dev.h
 *
 * low-level device information and state which is propagated up through
 * to high-level code.
 */

#ifndef _LINUX_BACKING_DEV_H
#define _LINUX_BACKING_DEV_H

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/blkdev.h>
#include <linux/writeback.h>
#include <linux/blk-cgroup.h>
#include <linux/backing-dev-defs.h>
#include <linux/slab.h>

static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
{
	kref_get(&bdi->refcnt);
	return bdi;
}

void bdi_put(struct backing_dev_info *bdi);

__printf(2, 3)
int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
		    va_list args);
int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
void bdi_unregister(struct backing_dev_info *bdi);

struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
static inline struct backing_dev_info *bdi_alloc(gfp_t gfp_mask)
{
	return bdi_alloc_node(gfp_mask, NUMA_NO_NODE);
}

void wb_start_background_writeback(struct bdi_writeback *wb);
void wb_workfn(struct work_struct *work);
void wb_wakeup_delayed(struct bdi_writeback *wb);

extern spinlock_t bdi_lock;
extern struct list_head bdi_list;

extern struct workqueue_struct *bdi_wq;

static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
{
	return test_bit(WB_has_dirty_io, &wb->state);
}

static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
{
	/*
	 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
	 * any dirty wbs.  See wb_update_write_bandwidth().
	 */
	return atomic_long_read(&bdi->tot_write_bandwidth);
}

static inline void __add_wb_stat(struct bdi_writeback *wb,
				 enum wb_stat_item item, s64 amount)
{
	percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);
}

static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
{
	__add_wb_stat(wb, item, 1);
}

static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
{
	__add_wb_stat(wb, item, -1);
}

static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
{
	return percpu_counter_read_positive(&wb->stat[item]);
}

static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
{
	return percpu_counter_sum_positive(&wb->stat[item]);
}

extern void wb_writeout_inc(struct bdi_writeback *wb);

/*
 * maximal error of a stat counter.
 */
static inline unsigned long wb_stat_error(void)
{
#ifdef CONFIG_SMP
	return nr_cpu_ids * WB_STAT_BATCH;
#else
	return 1;
#endif
}

int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);

/*
 * Flags in backing_dev_info::capability
 *
 * The first three flags control whether dirty pages will contribute to the
 * VM's accounting and whether writepages() should be called for dirty pages
 * (something that would not, for example, be appropriate for ramfs)
 *
 * WARNING: these flags are closely related and should not normally be
 * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
 * three flags into a single convenience macro.
 *
 * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
 * BDI_CAP_NO_WRITEBACK:   Don't write pages back
 * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
 * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold.
 *
 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
 * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
 *			   inefficient.
 */
#define BDI_CAP_NO_ACCT_DIRTY	0x00000001
#define BDI_CAP_NO_WRITEBACK	0x00000002
#define BDI_CAP_NO_ACCT_WB	0x00000004
#define BDI_CAP_STABLE_WRITES	0x00000008
#define BDI_CAP_STRICTLIMIT	0x00000010
#define BDI_CAP_CGROUP_WRITEBACK 0x00000020
#define BDI_CAP_SYNCHRONOUS_IO	0x00000040

#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
	(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)

extern struct backing_dev_info noop_backing_dev_info;

/**
 * writeback_in_progress - determine whether there is writeback in progress
 * @wb: bdi_writeback of interest
 *
 * Determine whether there is writeback waiting to be handled against a
 * bdi_writeback.
 */
static inline bool writeback_in_progress(struct bdi_writeback *wb)
{
	return test_bit(WB_writeback_running, &wb->state);
}

static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
{
	struct super_block *sb;

	if (!inode)
		return &noop_backing_dev_info;

	sb = inode->i_sb;
#ifdef CONFIG_BLOCK
	if (sb_is_blkdev_sb(sb))
		return I_BDEV(inode)->bd_bdi;
#endif
	return sb->s_bdi;
}

static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
{
	struct backing_dev_info *bdi = wb->bdi;

	if (bdi->congested_fn)
		return bdi->congested_fn(bdi->congested_data, cong_bits);
	return wb->congested->state & cong_bits;
}

long congestion_wait(int sync, long timeout);
long wait_iff_congested(int sync, long timeout);

static inline bool bdi_cap_synchronous_io(struct backing_dev_info *bdi)
{
	return bdi->capabilities & BDI_CAP_SYNCHRONOUS_IO;
}

static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
{
	return bdi->capabilities & BDI_CAP_STABLE_WRITES;
}

static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
{
	return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
}

static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
{
	return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
}

static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
{
	/* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
	return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
				      BDI_CAP_NO_WRITEBACK));
}

static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
{
	return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
}

static inline bool mapping_cap_account_dirty(struct address_space *mapping)
{
	return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
}

static inline int bdi_sched_wait(void *word)
{
	schedule();
	return 0;
}

#ifdef CONFIG_CGROUP_WRITEBACK

struct bdi_writeback_congested *
wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
void wb_congested_put(struct bdi_writeback_congested *congested);
struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
				    struct cgroup_subsys_state *memcg_css,
				    gfp_t gfp);
void wb_memcg_offline(struct mem_cgroup *memcg);
void wb_blkcg_offline(struct blkcg *blkcg);
int inode_congested(struct inode *inode, int cong_bits);

/**
 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
 * @inode: inode of interest
 *
 * cgroup writeback requires support from both the bdi and filesystem.
 * Also, both memcg and iocg have to be on the default hierarchy.  Test
 * whether all conditions are met.
 *
 * Note that the test result may change dynamically on the same inode
 * depending on how memcg and iocg are configured.
 */
static inline bool inode_cgwb_enabled(struct inode *inode)
{
	struct backing_dev_info *bdi = inode_to_bdi(inode);

	return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
		cgroup_subsys_on_dfl(io_cgrp_subsys) &&
		bdi_cap_account_dirty(bdi) &&
		(bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
		(inode->i_sb->s_iflags & SB_I_CGROUPWB);
}

/**
 * wb_find_current - find wb for %current on a bdi
 * @bdi: bdi of interest
 *
 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
 * Must be called under rcu_read_lock() which protects the returend wb.
 * NULL if not found.
 */
static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
{
	struct cgroup_subsys_state *memcg_css;
	struct bdi_writeback *wb;

	memcg_css = task_css(current, memory_cgrp_id);
	if (!memcg_css->parent)
		return &bdi->wb;

	wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);

	/*
	 * %current's blkcg equals the effective blkcg of its memcg.  No
	 * need to use the relatively expensive cgroup_get_e_css().
	 */
	if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
		return wb;
	return NULL;
}

/**
 * wb_get_create_current - get or create wb for %current on a bdi
 * @bdi: bdi of interest
 * @gfp: allocation mask
 *
 * Equivalent to wb_get_create() on %current's memcg.  This function is
 * called from a relatively hot path and optimizes the common cases using
 * wb_find_current().
 */
static inline struct bdi_writeback *
wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
{
	struct bdi_writeback *wb;

	rcu_read_lock();
	wb = wb_find_current(bdi);
	if (wb && unlikely(!wb_tryget(wb)))
		wb = NULL;
	rcu_read_unlock();

	if (unlikely(!wb)) {
		struct cgroup_subsys_state *memcg_css;

		memcg_css = task_get_css(current, memory_cgrp_id);
		wb = wb_get_create(bdi, memcg_css, gfp);
		css_put(memcg_css);
	}
	return wb;
}

/**
 * inode_to_wb_is_valid - test whether an inode has a wb associated
 * @inode: inode of interest
 *
 * Returns %true if @inode has a wb associated.  May be called without any
 * locking.
 */
static inline bool inode_to_wb_is_valid(struct inode *inode)
{
	return inode->i_wb;
}

/**
 * inode_to_wb - determine the wb of an inode
 * @inode: inode of interest
 *
 * Returns the wb @inode is currently associated with.  The caller must be
 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
 * associated wb's list_lock.
 */
static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
{
#ifdef CONFIG_LOCKDEP
	WARN_ON_ONCE(debug_locks &&
		     (!lockdep_is_held(&inode->i_lock) &&
		      !lockdep_is_held(&inode->i_mapping->tree_lock) &&
		      !lockdep_is_held(&inode->i_wb->list_lock)));
#endif
	return inode->i_wb;
}

/**
 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
 * @inode: target inode
 * @lockedp: temp bool output param, to be passed to the end function
 *
 * The caller wants to access the wb associated with @inode but isn't
 * holding inode->i_lock, mapping->tree_lock or wb->list_lock.  This
 * function determines the wb associated with @inode and ensures that the
 * association doesn't change until the transaction is finished with
 * unlocked_inode_to_wb_end().
 *
 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
 * afterwards and can't sleep during transaction.  IRQ may or may not be
 * disabled on return.
 */
static inline struct bdi_writeback *
unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
{
	rcu_read_lock();

	/*
	 * Paired with store_release in inode_switch_wb_work_fn() and
	 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
	 */
	*lockedp = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;

	if (unlikely(*lockedp))
		spin_lock_irq(&inode->i_mapping->tree_lock);

	/*
	 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
	 * inode_to_wb() will bark.  Deref directly.
	 */
	return inode->i_wb;
}

/**
 * unlocked_inode_to_wb_end - end inode wb access transaction
 * @inode: target inode
 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
 */
static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
{
	if (unlikely(locked))
		spin_unlock_irq(&inode->i_mapping->tree_lock);

	rcu_read_unlock();
}

#else	/* CONFIG_CGROUP_WRITEBACK */

static inline bool inode_cgwb_enabled(struct inode *inode)
{
	return false;
}

static inline struct bdi_writeback_congested *
wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
{
	atomic_inc(&bdi->wb_congested->refcnt);
	return bdi->wb_congested;
}

static inline void wb_congested_put(struct bdi_writeback_congested *congested)
{
	if (atomic_dec_and_test(&congested->refcnt))
		kfree(congested);
}

static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
{
	return &bdi->wb;
}

static inline struct bdi_writeback *
wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
{
	return &bdi->wb;
}

static inline bool inode_to_wb_is_valid(struct inode *inode)
{
	return true;
}

static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
{
	return &inode_to_bdi(inode)->wb;
}

static inline struct bdi_writeback *
unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp)
{
	return inode_to_wb(inode);
}

static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
{
}

static inline void wb_memcg_offline(struct mem_cgroup *memcg)
{
}

static inline void wb_blkcg_offline(struct blkcg *blkcg)
{
}

static inline int inode_congested(struct inode *inode, int cong_bits)
{
	return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
}

#endif	/* CONFIG_CGROUP_WRITEBACK */

static inline int inode_read_congested(struct inode *inode)
{
	return inode_congested(inode, 1 << WB_sync_congested);
}

static inline int inode_write_congested(struct inode *inode)
{
	return inode_congested(inode, 1 << WB_async_congested);
}

static inline int inode_rw_congested(struct inode *inode)
{
	return inode_congested(inode, (1 << WB_sync_congested) |
				      (1 << WB_async_congested));
}

static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
{
	return wb_congested(&bdi->wb, cong_bits);
}

static inline int bdi_read_congested(struct backing_dev_info *bdi)
{
	return bdi_congested(bdi, 1 << WB_sync_congested);
}

static inline int bdi_write_congested(struct backing_dev_info *bdi)
{
	return bdi_congested(bdi, 1 << WB_async_congested);
}

static inline int bdi_rw_congested(struct backing_dev_info *bdi)
{
	return bdi_congested(bdi, (1 << WB_sync_congested) |
				  (1 << WB_async_congested));
}

#endif	/* _LINUX_BACKING_DEV_H */