blob: 35b00746c712fc11776e78345edf786b98f9063b [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -070011#include <linux/percpu_counter.h>
12#include <linux/log2.h>
Peter Zijlstra04fbfdc2007-10-16 23:25:50 -070013#include <linux/proportions.h>
Peter Zijlstracf0ca9f2008-04-30 00:54:32 -070014#include <linux/kernel.h>
Miklos Szeredie4ad08f2008-04-30 00:54:37 -070015#include <linux/fs.h>
Jens Axboe03ba3782009-09-09 09:08:54 +020016#include <linux/sched.h>
Matthew Garrett31373d02010-04-06 14:25:14 +020017#include <linux/timer.h>
Jens Axboe03ba3782009-09-09 09:08:54 +020018#include <linux/writeback.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <asm/atomic.h>
20
Andrew Morton3fcfab12006-10-19 23:28:16 -070021struct page;
Peter Zijlstracf0ca9f2008-04-30 00:54:32 -070022struct device;
Miklos Szeredi76f14182008-04-30 00:54:36 -070023struct dentry;
Andrew Morton3fcfab12006-10-19 23:28:16 -070024
Linus Torvalds1da177e2005-04-16 15:20:36 -070025/*
26 * Bits in backing_dev_info.state
27 */
28enum bdi_state {
Jens Axboe03ba3782009-09-09 09:08:54 +020029 BDI_pending, /* On its way to being activated */
30 BDI_wb_alloc, /* Default embedded wb allocated */
Jens Axboe1faa16d2009-04-06 14:48:01 +020031 BDI_async_congested, /* The async (write) queue is getting full */
32 BDI_sync_congested, /* The sync queue is getting full */
Jens Axboe500b0672009-09-09 09:10:25 +020033 BDI_registered, /* bdi_register() was done */
Jan Kara81d73a32010-08-11 14:17:44 -070034 BDI_writeback_running, /* Writeback is in progress */
Linus Torvalds1da177e2005-04-16 15:20:36 -070035 BDI_unused, /* Available bits start here */
36};
37
38typedef int (congested_fn)(void *, int);
39
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -070040enum bdi_stat_item {
Peter Zijlstrac9e51e42007-10-16 23:25:47 -070041 BDI_RECLAIMABLE,
Peter Zijlstra69cb51d2007-10-16 23:25:48 -070042 BDI_WRITEBACK,
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -070043 NR_BDI_STAT_ITEMS
44};
45
46#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
47
Jens Axboe03ba3782009-09-09 09:08:54 +020048struct bdi_writeback {
Artem Bityutskiyecd58402010-07-25 14:29:18 +030049 struct backing_dev_info *bdi; /* our parent bdi */
Jens Axboe03ba3782009-09-09 09:08:54 +020050 unsigned int nr;
51
Artem Bityutskiyecd58402010-07-25 14:29:18 +030052 unsigned long last_old_flush; /* last old data flush */
53 unsigned long last_active; /* last time bdi thread was active */
Jens Axboe03ba3782009-09-09 09:08:54 +020054
Artem Bityutskiyecd58402010-07-25 14:29:18 +030055 struct task_struct *task; /* writeback thread */
Artem Bityutskiy64677162010-07-25 14:29:22 +030056 struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
Artem Bityutskiyecd58402010-07-25 14:29:18 +030057 struct list_head b_dirty; /* dirty inodes */
58 struct list_head b_io; /* parked for writeback */
59 struct list_head b_more_io; /* parked for more writeback */
Jens Axboe03ba3782009-09-09 09:08:54 +020060};
61
Linus Torvalds1da177e2005-04-16 15:20:36 -070062struct backing_dev_info {
Jens Axboe66f3b8e2009-09-02 09:19:46 +020063 struct list_head bdi_list;
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 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 void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
70 void *unplug_io_data;
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -070071
Jens Axboed9938312009-06-12 14:45:52 +020072 char *name;
73
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -070074 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
Peter Zijlstra04fbfdc2007-10-16 23:25:50 -070075
76 struct prop_local_percpu completions;
77 int dirty_exceeded;
Peter Zijlstracf0ca9f2008-04-30 00:54:32 -070078
Peter Zijlstra189d3c42008-04-30 00:54:35 -070079 unsigned int min_ratio;
Peter Zijlstraa42dde02008-04-30 00:54:36 -070080 unsigned int max_ratio, max_prop_frac;
Peter Zijlstra189d3c42008-04-30 00:54:35 -070081
Jens Axboe03ba3782009-09-09 09:08:54 +020082 struct bdi_writeback wb; /* default writeback info for this bdi */
Christoph Hellwigc1955ce2010-06-19 23:08:06 +020083 spinlock_t wb_lock; /* protects work_list */
Miklos Szeredi76f14182008-04-30 00:54:36 -070084
Jens Axboe03ba3782009-09-09 09:08:54 +020085 struct list_head work_list;
86
87 struct device *dev;
Jens Axboe66f3b8e2009-09-02 09:19:46 +020088
Matthew Garrett31373d02010-04-06 14:25:14 +020089 struct timer_list laptop_mode_wb_timer;
90
Miklos Szeredi76f14182008-04-30 00:54:36 -070091#ifdef CONFIG_DEBUG_FS
92 struct dentry *debug_dir;
93 struct dentry *debug_stats;
94#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070095};
96
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -070097int bdi_init(struct backing_dev_info *bdi);
98void bdi_destroy(struct backing_dev_info *bdi);
99
Peter Zijlstracf0ca9f2008-04-30 00:54:32 -0700100int bdi_register(struct backing_dev_info *bdi, struct device *parent,
101 const char *fmt, ...);
102int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
103void bdi_unregister(struct backing_dev_info *bdi);
Jens Axboec3c53202010-04-22 11:37:01 +0200104int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
Christoph Hellwigc5444192010-06-08 18:15:15 +0200105void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
106void bdi_start_background_writeback(struct backing_dev_info *bdi);
Christoph Hellwig08243902010-06-19 23:08:22 +0200107int bdi_writeback_thread(void *data);
Jens Axboe03ba3782009-09-09 09:08:54 +0200108int bdi_has_dirty_io(struct backing_dev_info *bdi);
Jens Axboe64231042010-05-21 20:00:35 +0200109void bdi_arm_supers_timer(void);
Artem Bityutskiy64677162010-07-25 14:29:22 +0300110void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
Peter Zijlstracf0ca9f2008-04-30 00:54:32 -0700111
Jens Axboe03ba3782009-09-09 09:08:54 +0200112extern spinlock_t bdi_lock;
Jens Axboe66f3b8e2009-09-02 09:19:46 +0200113extern struct list_head bdi_list;
114
Jens Axboe03ba3782009-09-09 09:08:54 +0200115static inline int wb_has_dirty_io(struct bdi_writeback *wb)
116{
117 return !list_empty(&wb->b_dirty) ||
118 !list_empty(&wb->b_io) ||
119 !list_empty(&wb->b_more_io);
120}
121
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -0700122static inline void __add_bdi_stat(struct backing_dev_info *bdi,
123 enum bdi_stat_item item, s64 amount)
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700124{
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -0700125 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700126}
127
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -0700128static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
129 enum bdi_stat_item item)
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700130{
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -0700131 __add_bdi_stat(bdi, item, 1);
132}
133
134static inline void inc_bdi_stat(struct backing_dev_info *bdi,
135 enum bdi_stat_item item)
136{
137 unsigned long flags;
138
139 local_irq_save(flags);
140 __inc_bdi_stat(bdi, item);
141 local_irq_restore(flags);
142}
143
144static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
145 enum bdi_stat_item item)
146{
147 __add_bdi_stat(bdi, item, -1);
148}
149
150static inline void dec_bdi_stat(struct backing_dev_info *bdi,
151 enum bdi_stat_item item)
152{
153 unsigned long flags;
154
155 local_irq_save(flags);
156 __dec_bdi_stat(bdi, item);
157 local_irq_restore(flags);
158}
159
160static inline s64 bdi_stat(struct backing_dev_info *bdi,
161 enum bdi_stat_item item)
162{
163 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
164}
165
166static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
167 enum bdi_stat_item item)
168{
169 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
170}
171
172static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
173 enum bdi_stat_item item)
174{
175 s64 sum;
176 unsigned long flags;
177
178 local_irq_save(flags);
179 sum = __bdi_stat_sum(bdi, item);
180 local_irq_restore(flags);
181
182 return sum;
183}
184
Miklos Szeredidd5656e2008-04-30 00:54:37 -0700185extern void bdi_writeout_inc(struct backing_dev_info *bdi);
186
Peter Zijlstrab2e8fb62007-10-16 23:25:47 -0700187/*
188 * maximal error of a stat counter.
189 */
190static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
191{
192#ifdef CONFIG_SMP
193 return nr_cpu_ids * BDI_STAT_BATCH;
194#else
195 return 1;
196#endif
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700197}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198
Peter Zijlstra189d3c42008-04-30 00:54:35 -0700199int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
Peter Zijlstraa42dde02008-04-30 00:54:36 -0700200int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
Peter Zijlstra189d3c42008-04-30 00:54:35 -0700201
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202/*
203 * Flags in backing_dev_info::capability
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700204 *
205 * The first three flags control whether dirty pages will contribute to the
206 * VM's accounting and whether writepages() should be called for dirty pages
207 * (something that would not, for example, be appropriate for ramfs)
208 *
209 * WARNING: these flags are closely related and should not normally be
210 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
211 * three flags into a single convenience macro.
212 *
213 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
214 * BDI_CAP_NO_WRITEBACK: Don't write pages back
215 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
216 *
217 * These flags let !MMU mmap() govern direct device mapping vs immediate
218 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
219 *
220 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
221 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
222 * BDI_CAP_READ_MAP: Can be mapped for reading
223 * BDI_CAP_WRITE_MAP: Can be mapped for writing
224 * BDI_CAP_EXEC_MAP: Can be mapped for execution
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700225 *
226 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 */
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700228#define BDI_CAP_NO_ACCT_DIRTY 0x00000001
229#define BDI_CAP_NO_WRITEBACK 0x00000002
230#define BDI_CAP_MAP_COPY 0x00000004
231#define BDI_CAP_MAP_DIRECT 0x00000008
232#define BDI_CAP_READ_MAP 0x00000010
233#define BDI_CAP_WRITE_MAP 0x00000020
234#define BDI_CAP_EXEC_MAP 0x00000040
235#define BDI_CAP_NO_ACCT_WB 0x00000080
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700236#define BDI_CAP_SWAP_BACKED 0x00000100
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700237
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238#define BDI_CAP_VMFLAGS \
239 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
240
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700241#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
242 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
243
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244#if defined(VM_MAYREAD) && \
245 (BDI_CAP_READ_MAP != VM_MAYREAD || \
246 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
247 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
248#error please change backing_dev_info::capabilities flags
249#endif
250
251extern struct backing_dev_info default_backing_dev_info;
Jörn Engel5129a462010-04-25 08:54:42 +0200252extern struct backing_dev_info noop_backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
254
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255int writeback_in_progress(struct backing_dev_info *bdi);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256
257static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
258{
259 if (bdi->congested_fn)
260 return bdi->congested_fn(bdi->congested_data, bdi_bits);
261 return (bdi->state & bdi_bits);
262}
263
264static inline int bdi_read_congested(struct backing_dev_info *bdi)
265{
Jens Axboe1faa16d2009-04-06 14:48:01 +0200266 return bdi_congested(bdi, 1 << BDI_sync_congested);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267}
268
269static inline int bdi_write_congested(struct backing_dev_info *bdi)
270{
Jens Axboe1faa16d2009-04-06 14:48:01 +0200271 return bdi_congested(bdi, 1 << BDI_async_congested);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272}
273
274static inline int bdi_rw_congested(struct backing_dev_info *bdi)
275{
Jens Axboe1faa16d2009-04-06 14:48:01 +0200276 return bdi_congested(bdi, (1 << BDI_sync_congested) |
277 (1 << BDI_async_congested));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278}
279
Trond Myklebust373c0a72009-07-11 10:06:54 -0400280enum {
281 BLK_RW_ASYNC = 0,
282 BLK_RW_SYNC = 1,
283};
284
Jens Axboe8aa7e842009-07-09 14:52:32 +0200285void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
286void set_bdi_congested(struct backing_dev_info *bdi, int sync);
287long congestion_wait(int sync, long timeout);
Andrew Morton3fcfab12006-10-19 23:28:16 -0700288
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700290static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
291{
292 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
293}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700295static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
296{
297 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
298}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700300static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
301{
302 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
303 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
304 BDI_CAP_NO_WRITEBACK));
305}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700307static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
308{
309 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
310}
311
Jens Axboe03ba3782009-09-09 09:08:54 +0200312static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
313{
314 return bdi == &default_backing_dev_info;
315}
316
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700317static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
318{
319 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
320}
321
322static inline bool mapping_cap_account_dirty(struct address_space *mapping)
323{
324 return bdi_cap_account_dirty(mapping->backing_dev_info);
325}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700327static inline bool mapping_cap_swap_backed(struct address_space *mapping)
328{
329 return bdi_cap_swap_backed(mapping->backing_dev_info);
330}
331
Jens Axboe03ba3782009-09-09 09:08:54 +0200332static inline int bdi_sched_wait(void *word)
333{
334 schedule();
335 return 0;
336}
337
Jens Axboeb9d128f2009-10-29 13:59:26 +0100338static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
339 struct page *page)
340{
341 if (bdi && bdi->unplug_io_fn)
342 bdi->unplug_io_fn(bdi, page);
343}
344
345static inline void blk_run_address_space(struct address_space *mapping)
346{
347 if (mapping)
348 blk_run_backing_dev(mapping->backing_dev_info, NULL);
349}
350
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351#endif /* _LINUX_BACKING_DEV_H */