1/*
2 * include/linux/backing-dev.h
3 *
4 * low-level device information and state which is propagated up through
5 * to high-level code.
6 */
7
8#ifndef _LINUX_BACKING_DEV_H
9#define _LINUX_BACKING_DEV_H
10
11#include <linux/percpu_counter.h>
12#include <linux/log2.h>
13#include <linux/flex_proportions.h>
14#include <linux/kernel.h>
15#include <linux/fs.h>
16#include <linux/sched.h>
17#include <linux/timer.h>
18#include <linux/writeback.h>
19#include <linux/atomic.h>
20#include <linux/sysctl.h>
21#include <linux/workqueue.h>
22
23struct page;
24struct device;
25struct dentry;
26
27/*
28 * Bits in backing_dev_info.state
29 */
30enum bdi_state {
31	BDI_async_congested,	/* The async (write) queue is getting full */
32	BDI_sync_congested,	/* The sync queue is getting full */
33	BDI_registered,		/* bdi_register() was done */
34	BDI_writeback_running,	/* Writeback is in progress */
35};
36
37typedef int (congested_fn)(void *, int);
38
39enum bdi_stat_item {
40	BDI_RECLAIMABLE,
41	BDI_WRITEBACK,
42	BDI_DIRTIED,
43	BDI_WRITTEN,
44	NR_BDI_STAT_ITEMS
45};
46
47#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
48
49struct bdi_writeback {
50	struct backing_dev_info *bdi;	/* our parent bdi */
51
52	unsigned long last_old_flush;	/* last old data flush */
53
54	struct delayed_work dwork;	/* work item used for writeback */
55	struct list_head b_dirty;	/* dirty inodes */
56	struct list_head b_io;		/* parked for writeback */
57	struct list_head b_more_io;	/* parked for more writeback */
58	struct list_head b_dirty_time;	/* time stamps are dirty */
59	spinlock_t list_lock;		/* protects the b_* lists */
60};
61
62struct backing_dev_info {
63	struct list_head bdi_list;
64	unsigned long ra_pages;	/* max readahead in PAGE_CACHE_SIZE units */
65	unsigned long state;	/* Always use atomic bitops on this */
66	unsigned int capabilities; /* Device capabilities */
67	congested_fn *congested_fn; /* Function pointer if device is md/dm */
68	void *congested_data;	/* Pointer to aux data for congested func */
69
70	char *name;
71
72	struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
73
74	unsigned long bw_time_stamp;	/* last time write bw is updated */
75	unsigned long dirtied_stamp;
76	unsigned long written_stamp;	/* pages written at bw_time_stamp */
77	unsigned long write_bandwidth;	/* the estimated write bandwidth */
78	unsigned long avg_write_bandwidth; /* further smoothed write bw */
79
80	/*
81	 * The base dirty throttle rate, re-calculated on every 200ms.
82	 * All the bdi tasks' dirty rate will be curbed under it.
83	 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
84	 * in small steps and is much more smooth/stable than the latter.
85	 */
86	unsigned long dirty_ratelimit;
87	unsigned long balanced_dirty_ratelimit;
88
89	struct fprop_local_percpu completions;
90	int dirty_exceeded;
91
92	unsigned int min_ratio;
93	unsigned int max_ratio, max_prop_frac;
94
95	struct bdi_writeback wb;  /* default writeback info for this bdi */
96	spinlock_t wb_lock;	  /* protects work_list & wb.dwork scheduling */
97
98	struct list_head work_list;
99
100	struct device *dev;
101
102	struct timer_list laptop_mode_wb_timer;
103
104#ifdef CONFIG_DEBUG_FS
105	struct dentry *debug_dir;
106	struct dentry *debug_stats;
107#endif
108};
109
110struct backing_dev_info *inode_to_bdi(struct inode *inode);
111
112int __must_check bdi_init(struct backing_dev_info *bdi);
113void bdi_destroy(struct backing_dev_info *bdi);
114
115__printf(3, 4)
116int bdi_register(struct backing_dev_info *bdi, struct device *parent,
117		const char *fmt, ...);
118int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
119int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
120void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
121			enum wb_reason reason);
122void bdi_start_background_writeback(struct backing_dev_info *bdi);
123void bdi_writeback_workfn(struct work_struct *work);
124int bdi_has_dirty_io(struct backing_dev_info *bdi);
125void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
126
127extern spinlock_t bdi_lock;
128extern struct list_head bdi_list;
129
130extern struct workqueue_struct *bdi_wq;
131
132static inline int wb_has_dirty_io(struct bdi_writeback *wb)
133{
134	return !list_empty(&wb->b_dirty) ||
135	       !list_empty(&wb->b_io) ||
136	       !list_empty(&wb->b_more_io);
137}
138
139static inline void __add_bdi_stat(struct backing_dev_info *bdi,
140		enum bdi_stat_item item, s64 amount)
141{
142	__percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
143}
144
145static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
146		enum bdi_stat_item item)
147{
148	__add_bdi_stat(bdi, item, 1);
149}
150
151static inline void inc_bdi_stat(struct backing_dev_info *bdi,
152		enum bdi_stat_item item)
153{
154	unsigned long flags;
155
156	local_irq_save(flags);
157	__inc_bdi_stat(bdi, item);
158	local_irq_restore(flags);
159}
160
161static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
162		enum bdi_stat_item item)
163{
164	__add_bdi_stat(bdi, item, -1);
165}
166
167static inline void dec_bdi_stat(struct backing_dev_info *bdi,
168		enum bdi_stat_item item)
169{
170	unsigned long flags;
171
172	local_irq_save(flags);
173	__dec_bdi_stat(bdi, item);
174	local_irq_restore(flags);
175}
176
177static inline s64 bdi_stat(struct backing_dev_info *bdi,
178		enum bdi_stat_item item)
179{
180	return percpu_counter_read_positive(&bdi->bdi_stat[item]);
181}
182
183static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
184		enum bdi_stat_item item)
185{
186	return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
187}
188
189static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
190		enum bdi_stat_item item)
191{
192	s64 sum;
193	unsigned long flags;
194
195	local_irq_save(flags);
196	sum = __bdi_stat_sum(bdi, item);
197	local_irq_restore(flags);
198
199	return sum;
200}
201
202extern void bdi_writeout_inc(struct backing_dev_info *bdi);
203
204/*
205 * maximal error of a stat counter.
206 */
207static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
208{
209#ifdef CONFIG_SMP
210	return nr_cpu_ids * BDI_STAT_BATCH;
211#else
212	return 1;
213#endif
214}
215
216int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
217int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
218
219/*
220 * Flags in backing_dev_info::capability
221 *
222 * The first three flags control whether dirty pages will contribute to the
223 * VM's accounting and whether writepages() should be called for dirty pages
224 * (something that would not, for example, be appropriate for ramfs)
225 *
226 * WARNING: these flags are closely related and should not normally be
227 * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
228 * three flags into a single convenience macro.
229 *
230 * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
231 * BDI_CAP_NO_WRITEBACK:   Don't write pages back
232 * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
233 * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold.
234 */
235#define BDI_CAP_NO_ACCT_DIRTY	0x00000001
236#define BDI_CAP_NO_WRITEBACK	0x00000002
237#define BDI_CAP_NO_ACCT_WB	0x00000004
238#define BDI_CAP_STABLE_WRITES	0x00000008
239#define BDI_CAP_STRICTLIMIT	0x00000010
240
241#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
242	(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
243
244extern struct backing_dev_info noop_backing_dev_info;
245
246int writeback_in_progress(struct backing_dev_info *bdi);
247
248static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
249{
250	if (bdi->congested_fn)
251		return bdi->congested_fn(bdi->congested_data, bdi_bits);
252	return (bdi->state & bdi_bits);
253}
254
255static inline int bdi_read_congested(struct backing_dev_info *bdi)
256{
257	return bdi_congested(bdi, 1 << BDI_sync_congested);
258}
259
260static inline int bdi_write_congested(struct backing_dev_info *bdi)
261{
262	return bdi_congested(bdi, 1 << BDI_async_congested);
263}
264
265static inline int bdi_rw_congested(struct backing_dev_info *bdi)
266{
267	return bdi_congested(bdi, (1 << BDI_sync_congested) |
268				  (1 << BDI_async_congested));
269}
270
271enum {
272	BLK_RW_ASYNC	= 0,
273	BLK_RW_SYNC	= 1,
274};
275
276void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
277void set_bdi_congested(struct backing_dev_info *bdi, int sync);
278long congestion_wait(int sync, long timeout);
279long wait_iff_congested(struct zone *zone, int sync, long timeout);
280int pdflush_proc_obsolete(struct ctl_table *table, int write,
281		void __user *buffer, size_t *lenp, loff_t *ppos);
282
283static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
284{
285	return bdi->capabilities & BDI_CAP_STABLE_WRITES;
286}
287
288static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
289{
290	return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
291}
292
293static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
294{
295	return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
296}
297
298static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
299{
300	/* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
301	return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
302				      BDI_CAP_NO_WRITEBACK));
303}
304
305static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
306{
307	return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
308}
309
310static inline bool mapping_cap_account_dirty(struct address_space *mapping)
311{
312	return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
313}
314
315static inline int bdi_sched_wait(void *word)
316{
317	schedule();
318	return 0;
319}
320
321#endif		/* _LINUX_BACKING_DEV_H */
322