Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Uwe Zeisberger | f30c226 | 2006-10-03 23:01:26 +0200 | [diff] [blame] | 2 | * mm/page-writeback.c |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * |
| 4 | * Copyright (C) 2002, Linus Torvalds. |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 5 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 6 | * |
| 7 | * Contains functions related to writing back dirty pages at the |
| 8 | * address_space level. |
| 9 | * |
Francois Cami | e1f8e87 | 2008-10-15 22:01:59 -0700 | [diff] [blame] | 10 | * 10Apr2002 Andrew Morton |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | * Initial version |
| 12 | */ |
| 13 | |
| 14 | #include <linux/kernel.h> |
Paul Gortmaker | b95f1b31 | 2011-10-16 02:01:52 -0400 | [diff] [blame] | 15 | #include <linux/export.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/spinlock.h> |
| 17 | #include <linux/fs.h> |
| 18 | #include <linux/mm.h> |
| 19 | #include <linux/swap.h> |
| 20 | #include <linux/slab.h> |
| 21 | #include <linux/pagemap.h> |
| 22 | #include <linux/writeback.h> |
| 23 | #include <linux/init.h> |
| 24 | #include <linux/backing-dev.h> |
Andrew Morton | 55e829a | 2006-12-10 02:19:27 -0800 | [diff] [blame] | 25 | #include <linux/task_io_accounting_ops.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | #include <linux/blkdev.h> |
| 27 | #include <linux/mpage.h> |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 28 | #include <linux/rmap.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | #include <linux/percpu.h> |
| 30 | #include <linux/notifier.h> |
| 31 | #include <linux/smp.h> |
| 32 | #include <linux/sysctl.h> |
| 33 | #include <linux/cpu.h> |
| 34 | #include <linux/syscalls.h> |
Al Viro | ff01bb48 | 2011-09-16 02:31:11 -0400 | [diff] [blame] | 35 | #include <linux/buffer_head.h> /* __set_page_dirty_buffers */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 36 | #include <linux/pagevec.h> |
Dave Chinner | 028c2dd | 2010-07-07 13:24:07 +1000 | [diff] [blame] | 37 | #include <trace/events/writeback.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | |
| 39 | /* |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 40 | * Sleep at most 200ms at a time in balance_dirty_pages(). |
| 41 | */ |
| 42 | #define MAX_PAUSE max(HZ/5, 1) |
| 43 | |
| 44 | /* |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 45 | * Estimate write bandwidth at 200ms intervals. |
| 46 | */ |
| 47 | #define BANDWIDTH_INTERVAL max(HZ/5, 1) |
| 48 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 49 | #define RATELIMIT_CALC_SHIFT 10 |
| 50 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 51 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited |
| 53 | * will look to see if it needs to force writeback or throttling. |
| 54 | */ |
| 55 | static long ratelimit_pages = 32; |
| 56 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | /* The following parameters are exported via /proc/sys/vm */ |
| 58 | |
| 59 | /* |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 60 | * Start background writeback (via writeback threads) at this percentage |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 61 | */ |
Wu Fengguang | 1b5e62b | 2009-03-23 08:57:38 +0800 | [diff] [blame] | 62 | int dirty_background_ratio = 10; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | |
| 64 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 65 | * dirty_background_bytes starts at 0 (disabled) so that it is a function of |
| 66 | * dirty_background_ratio * the amount of dirtyable memory |
| 67 | */ |
| 68 | unsigned long dirty_background_bytes; |
| 69 | |
| 70 | /* |
Bron Gondwana | 195cf453 | 2008-02-04 22:29:20 -0800 | [diff] [blame] | 71 | * free highmem will not be subtracted from the total free memory |
| 72 | * for calculating free ratios if vm_highmem_is_dirtyable is true |
| 73 | */ |
| 74 | int vm_highmem_is_dirtyable; |
| 75 | |
| 76 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 77 | * The generator of dirty data starts writeback at this percentage |
| 78 | */ |
Wu Fengguang | 1b5e62b | 2009-03-23 08:57:38 +0800 | [diff] [blame] | 79 | int vm_dirty_ratio = 20; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 80 | |
| 81 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 82 | * vm_dirty_bytes starts at 0 (disabled) so that it is a function of |
| 83 | * vm_dirty_ratio * the amount of dirtyable memory |
| 84 | */ |
| 85 | unsigned long vm_dirty_bytes; |
| 86 | |
| 87 | /* |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 88 | * The interval between `kupdate'-style writebacks |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 89 | */ |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 90 | unsigned int dirty_writeback_interval = 5 * 100; /* centiseconds */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 91 | |
| 92 | /* |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 93 | * The longest time for which data is allowed to remain dirty |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 94 | */ |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 95 | unsigned int dirty_expire_interval = 30 * 100; /* centiseconds */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | |
| 97 | /* |
| 98 | * Flag that makes the machine dump writes/reads and block dirtyings. |
| 99 | */ |
| 100 | int block_dump; |
| 101 | |
| 102 | /* |
Bart Samwel | ed5b43f | 2006-03-24 03:15:49 -0800 | [diff] [blame] | 103 | * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies: |
| 104 | * a full sync is triggered after this time elapses without any disk activity. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | */ |
| 106 | int laptop_mode; |
| 107 | |
| 108 | EXPORT_SYMBOL(laptop_mode); |
| 109 | |
| 110 | /* End of sysctl-exported parameters */ |
| 111 | |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 112 | unsigned long global_dirty_limit; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 113 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | /* |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 115 | * Scale the writeback cache size proportional to the relative writeout speeds. |
| 116 | * |
| 117 | * We do this by keeping a floating proportion between BDIs, based on page |
| 118 | * writeback completions [end_page_writeback()]. Those devices that write out |
| 119 | * pages fastest will get the larger share, while the slower will get a smaller |
| 120 | * share. |
| 121 | * |
| 122 | * We use page writeout completions because we are interested in getting rid of |
| 123 | * dirty pages. Having them written out is the primary goal. |
| 124 | * |
| 125 | * We introduce a concept of time, a period over which we measure these events, |
| 126 | * because demand can/will vary over time. The length of this period itself is |
| 127 | * measured in page writeback completions. |
| 128 | * |
| 129 | */ |
| 130 | static struct prop_descriptor vm_completions; |
| 131 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 132 | /* |
| 133 | * couple the period to the dirty_ratio: |
| 134 | * |
| 135 | * period/2 ~ roundup_pow_of_two(dirty limit) |
| 136 | */ |
| 137 | static int calc_period_shift(void) |
| 138 | { |
| 139 | unsigned long dirty_total; |
| 140 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 141 | if (vm_dirty_bytes) |
| 142 | dirty_total = vm_dirty_bytes / PAGE_SIZE; |
| 143 | else |
| 144 | dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) / |
| 145 | 100; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 146 | return 2 + ilog2(dirty_total - 1); |
| 147 | } |
| 148 | |
| 149 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 150 | * update the period when the dirty threshold changes. |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 151 | */ |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 152 | static void update_completion_period(void) |
| 153 | { |
| 154 | int shift = calc_period_shift(); |
| 155 | prop_change_shift(&vm_completions, shift); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 156 | |
| 157 | writeback_set_ratelimit(); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 158 | } |
| 159 | |
| 160 | int dirty_background_ratio_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 161 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 162 | loff_t *ppos) |
| 163 | { |
| 164 | int ret; |
| 165 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 166 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 167 | if (ret == 0 && write) |
| 168 | dirty_background_bytes = 0; |
| 169 | return ret; |
| 170 | } |
| 171 | |
| 172 | int dirty_background_bytes_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 173 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 174 | loff_t *ppos) |
| 175 | { |
| 176 | int ret; |
| 177 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 178 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 179 | if (ret == 0 && write) |
| 180 | dirty_background_ratio = 0; |
| 181 | return ret; |
| 182 | } |
| 183 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 184 | int dirty_ratio_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 185 | void __user *buffer, size_t *lenp, |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 186 | loff_t *ppos) |
| 187 | { |
| 188 | int old_ratio = vm_dirty_ratio; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 189 | int ret; |
| 190 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 191 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 192 | if (ret == 0 && write && vm_dirty_ratio != old_ratio) { |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 193 | update_completion_period(); |
| 194 | vm_dirty_bytes = 0; |
| 195 | } |
| 196 | return ret; |
| 197 | } |
| 198 | |
| 199 | |
| 200 | int dirty_bytes_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 201 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 202 | loff_t *ppos) |
| 203 | { |
Sven Wegener | fc3501d | 2009-02-11 13:04:23 -0800 | [diff] [blame] | 204 | unsigned long old_bytes = vm_dirty_bytes; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 205 | int ret; |
| 206 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 207 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 208 | if (ret == 0 && write && vm_dirty_bytes != old_bytes) { |
| 209 | update_completion_period(); |
| 210 | vm_dirty_ratio = 0; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 211 | } |
| 212 | return ret; |
| 213 | } |
| 214 | |
| 215 | /* |
| 216 | * Increment the BDI's writeout completion count and the global writeout |
| 217 | * completion count. Called from test_clear_page_writeback(). |
| 218 | */ |
| 219 | static inline void __bdi_writeout_inc(struct backing_dev_info *bdi) |
| 220 | { |
Jan Kara | f7d2b1e | 2010-12-08 22:44:24 -0600 | [diff] [blame] | 221 | __inc_bdi_stat(bdi, BDI_WRITTEN); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 222 | __prop_inc_percpu_max(&vm_completions, &bdi->completions, |
| 223 | bdi->max_prop_frac); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 224 | } |
| 225 | |
Miklos Szeredi | dd5656e | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 226 | void bdi_writeout_inc(struct backing_dev_info *bdi) |
| 227 | { |
| 228 | unsigned long flags; |
| 229 | |
| 230 | local_irq_save(flags); |
| 231 | __bdi_writeout_inc(bdi); |
| 232 | local_irq_restore(flags); |
| 233 | } |
| 234 | EXPORT_SYMBOL_GPL(bdi_writeout_inc); |
| 235 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 236 | /* |
| 237 | * Obtain an accurate fraction of the BDI's portion. |
| 238 | */ |
| 239 | static void bdi_writeout_fraction(struct backing_dev_info *bdi, |
| 240 | long *numerator, long *denominator) |
| 241 | { |
Wu Fengguang | 3efaf0f | 2010-12-16 22:22:00 -0600 | [diff] [blame] | 242 | prop_fraction_percpu(&vm_completions, &bdi->completions, |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 243 | numerator, denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 244 | } |
| 245 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 246 | /* |
Johannes Weiner | d08c429 | 2011-10-31 17:07:05 -0700 | [diff] [blame] | 247 | * bdi_min_ratio keeps the sum of the minimum dirty shares of all |
| 248 | * registered backing devices, which, for obvious reasons, can not |
| 249 | * exceed 100%. |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 250 | */ |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 251 | static unsigned int bdi_min_ratio; |
| 252 | |
| 253 | int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) |
| 254 | { |
| 255 | int ret = 0; |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 256 | |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 257 | spin_lock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 258 | if (min_ratio > bdi->max_ratio) { |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 259 | ret = -EINVAL; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 260 | } else { |
| 261 | min_ratio -= bdi->min_ratio; |
| 262 | if (bdi_min_ratio + min_ratio < 100) { |
| 263 | bdi_min_ratio += min_ratio; |
| 264 | bdi->min_ratio += min_ratio; |
| 265 | } else { |
| 266 | ret = -EINVAL; |
| 267 | } |
| 268 | } |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 269 | spin_unlock_bh(&bdi_lock); |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 270 | |
| 271 | return ret; |
| 272 | } |
| 273 | |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 274 | int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) |
| 275 | { |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 276 | int ret = 0; |
| 277 | |
| 278 | if (max_ratio > 100) |
| 279 | return -EINVAL; |
| 280 | |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 281 | spin_lock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 282 | if (bdi->min_ratio > max_ratio) { |
| 283 | ret = -EINVAL; |
| 284 | } else { |
| 285 | bdi->max_ratio = max_ratio; |
| 286 | bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100; |
| 287 | } |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 288 | spin_unlock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 289 | |
| 290 | return ret; |
| 291 | } |
| 292 | EXPORT_SYMBOL(bdi_set_max_ratio); |
| 293 | |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 294 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 295 | * Work out the current dirty-memory clamping and background writeout |
| 296 | * thresholds. |
| 297 | * |
| 298 | * The main aim here is to lower them aggressively if there is a lot of mapped |
| 299 | * memory around. To avoid stressing page reclaim with lots of unreclaimable |
| 300 | * pages. It is better to clamp down on writers than to start swapping, and |
| 301 | * performing lots of scanning. |
| 302 | * |
| 303 | * We only allow 1/2 of the currently-unmapped memory to be dirtied. |
| 304 | * |
| 305 | * We don't permit the clamping level to fall below 5% - that is getting rather |
| 306 | * excessive. |
| 307 | * |
| 308 | * We make sure that the background writeout level is below the adjusted |
| 309 | * clamping level. |
| 310 | */ |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 311 | |
| 312 | static unsigned long highmem_dirtyable_memory(unsigned long total) |
| 313 | { |
| 314 | #ifdef CONFIG_HIGHMEM |
| 315 | int node; |
| 316 | unsigned long x = 0; |
| 317 | |
Lee Schermerhorn | 37b07e4 | 2007-10-16 01:25:39 -0700 | [diff] [blame] | 318 | for_each_node_state(node, N_HIGH_MEMORY) { |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 319 | struct zone *z = |
| 320 | &NODE_DATA(node)->node_zones[ZONE_HIGHMEM]; |
| 321 | |
Wu Fengguang | adea02a | 2009-09-21 17:01:42 -0700 | [diff] [blame] | 322 | x += zone_page_state(z, NR_FREE_PAGES) + |
| 323 | zone_reclaimable_pages(z); |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 324 | } |
| 325 | /* |
| 326 | * Make sure that the number of highmem pages is never larger |
| 327 | * than the number of the total dirtyable memory. This can only |
| 328 | * occur in very strange VM situations but we want to make sure |
| 329 | * that this does not occur. |
| 330 | */ |
| 331 | return min(x, total); |
| 332 | #else |
| 333 | return 0; |
| 334 | #endif |
| 335 | } |
| 336 | |
Steven Rostedt | 3eefae9 | 2008-05-12 21:21:04 +0200 | [diff] [blame] | 337 | /** |
| 338 | * determine_dirtyable_memory - amount of memory that may be used |
| 339 | * |
| 340 | * Returns the numebr of pages that can currently be freed and used |
| 341 | * by the kernel for direct mappings. |
| 342 | */ |
| 343 | unsigned long determine_dirtyable_memory(void) |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 344 | { |
| 345 | unsigned long x; |
| 346 | |
Wu Fengguang | adea02a | 2009-09-21 17:01:42 -0700 | [diff] [blame] | 347 | x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages(); |
Bron Gondwana | 195cf453 | 2008-02-04 22:29:20 -0800 | [diff] [blame] | 348 | |
| 349 | if (!vm_highmem_is_dirtyable) |
| 350 | x -= highmem_dirtyable_memory(x); |
| 351 | |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 352 | return x + 1; /* Ensure that we never return 0 */ |
| 353 | } |
| 354 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 355 | static unsigned long dirty_freerun_ceiling(unsigned long thresh, |
| 356 | unsigned long bg_thresh) |
| 357 | { |
| 358 | return (thresh + bg_thresh) / 2; |
| 359 | } |
| 360 | |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 361 | static unsigned long hard_dirty_limit(unsigned long thresh) |
| 362 | { |
| 363 | return max(thresh, global_dirty_limit); |
| 364 | } |
| 365 | |
Randy Dunlap | 03ab450 | 2010-08-14 13:05:17 -0700 | [diff] [blame] | 366 | /* |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 367 | * global_dirty_limits - background-writeback and dirty-throttling thresholds |
| 368 | * |
| 369 | * Calculate the dirty thresholds based on sysctl parameters |
| 370 | * - vm.dirty_background_ratio or vm.dirty_background_bytes |
| 371 | * - vm.dirty_ratio or vm.dirty_bytes |
| 372 | * The dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and |
Minchan Kim | ebd1373 | 2011-01-04 01:36:48 +0900 | [diff] [blame] | 373 | * real-time tasks. |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 374 | */ |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 375 | void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 376 | { |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 377 | unsigned long background; |
| 378 | unsigned long dirty; |
Minchan Kim | 240c879 | 2011-01-13 15:46:27 -0800 | [diff] [blame] | 379 | unsigned long uninitialized_var(available_memory); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 380 | struct task_struct *tsk; |
| 381 | |
Minchan Kim | 240c879 | 2011-01-13 15:46:27 -0800 | [diff] [blame] | 382 | if (!vm_dirty_bytes || !dirty_background_bytes) |
| 383 | available_memory = determine_dirtyable_memory(); |
| 384 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 385 | if (vm_dirty_bytes) |
| 386 | dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE); |
Wu Fengguang | 4cbec4c | 2010-10-26 14:21:45 -0700 | [diff] [blame] | 387 | else |
| 388 | dirty = (vm_dirty_ratio * available_memory) / 100; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 389 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 390 | if (dirty_background_bytes) |
| 391 | background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE); |
| 392 | else |
| 393 | background = (dirty_background_ratio * available_memory) / 100; |
| 394 | |
| 395 | if (background >= dirty) |
| 396 | background = dirty / 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 397 | tsk = current; |
| 398 | if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) { |
| 399 | background += background / 4; |
| 400 | dirty += dirty / 4; |
| 401 | } |
| 402 | *pbackground = background; |
| 403 | *pdirty = dirty; |
Wu Fengguang | e1cbe23 | 2010-12-06 22:34:29 -0600 | [diff] [blame] | 404 | trace_global_dirty_state(background, dirty); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 405 | } |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 406 | |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 407 | /** |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 408 | * bdi_dirty_limit - @bdi's share of dirty throttling threshold |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 409 | * @bdi: the backing_dev_info to query |
| 410 | * @dirty: global dirty limit in pages |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 411 | * |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 412 | * Returns @bdi's dirty limit in pages. The term "dirty" in the context of |
| 413 | * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages. |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 414 | * |
| 415 | * Note that balance_dirty_pages() will only seriously take it as a hard limit |
| 416 | * when sleeping max_pause per page is not enough to keep the dirty pages under |
| 417 | * control. For example, when the device is completely stalled due to some error |
| 418 | * conditions, or when there are 1000 dd tasks writing to a slow 10MB/s USB key. |
| 419 | * In the other normal situations, it acts more gently by throttling the tasks |
| 420 | * more (rather than completely block them) when the bdi dirty pages go high. |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 421 | * |
| 422 | * It allocates high/low dirty limits to fast/slow devices, in order to prevent |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 423 | * - starving fast devices |
| 424 | * - piling up dirty pages (that will take long time to sync) on slow devices |
| 425 | * |
| 426 | * The bdi's share of dirty limit will be adapting to its throughput and |
| 427 | * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set. |
| 428 | */ |
| 429 | unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, unsigned long dirty) |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 430 | { |
| 431 | u64 bdi_dirty; |
| 432 | long numerator, denominator; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 433 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 434 | /* |
| 435 | * Calculate this BDI's share of the dirty ratio. |
| 436 | */ |
| 437 | bdi_writeout_fraction(bdi, &numerator, &denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 438 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 439 | bdi_dirty = (dirty * (100 - bdi_min_ratio)) / 100; |
| 440 | bdi_dirty *= numerator; |
| 441 | do_div(bdi_dirty, denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 442 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 443 | bdi_dirty += (dirty * bdi->min_ratio) / 100; |
| 444 | if (bdi_dirty > (dirty * bdi->max_ratio) / 100) |
| 445 | bdi_dirty = dirty * bdi->max_ratio / 100; |
| 446 | |
| 447 | return bdi_dirty; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 448 | } |
| 449 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 450 | /* |
| 451 | * Dirty position control. |
| 452 | * |
| 453 | * (o) global/bdi setpoints |
| 454 | * |
| 455 | * We want the dirty pages be balanced around the global/bdi setpoints. |
| 456 | * When the number of dirty pages is higher/lower than the setpoint, the |
| 457 | * dirty position control ratio (and hence task dirty ratelimit) will be |
| 458 | * decreased/increased to bring the dirty pages back to the setpoint. |
| 459 | * |
| 460 | * pos_ratio = 1 << RATELIMIT_CALC_SHIFT |
| 461 | * |
| 462 | * if (dirty < setpoint) scale up pos_ratio |
| 463 | * if (dirty > setpoint) scale down pos_ratio |
| 464 | * |
| 465 | * if (bdi_dirty < bdi_setpoint) scale up pos_ratio |
| 466 | * if (bdi_dirty > bdi_setpoint) scale down pos_ratio |
| 467 | * |
| 468 | * task_ratelimit = dirty_ratelimit * pos_ratio >> RATELIMIT_CALC_SHIFT |
| 469 | * |
| 470 | * (o) global control line |
| 471 | * |
| 472 | * ^ pos_ratio |
| 473 | * | |
| 474 | * | |<===== global dirty control scope ======>| |
| 475 | * 2.0 .............* |
| 476 | * | .* |
| 477 | * | . * |
| 478 | * | . * |
| 479 | * | . * |
| 480 | * | . * |
| 481 | * | . * |
| 482 | * 1.0 ................................* |
| 483 | * | . . * |
| 484 | * | . . * |
| 485 | * | . . * |
| 486 | * | . . * |
| 487 | * | . . * |
| 488 | * 0 +------------.------------------.----------------------*-------------> |
| 489 | * freerun^ setpoint^ limit^ dirty pages |
| 490 | * |
| 491 | * (o) bdi control line |
| 492 | * |
| 493 | * ^ pos_ratio |
| 494 | * | |
| 495 | * | * |
| 496 | * | * |
| 497 | * | * |
| 498 | * | * |
| 499 | * | * |<=========== span ============>| |
| 500 | * 1.0 .......................* |
| 501 | * | . * |
| 502 | * | . * |
| 503 | * | . * |
| 504 | * | . * |
| 505 | * | . * |
| 506 | * | . * |
| 507 | * | . * |
| 508 | * | . * |
| 509 | * | . * |
| 510 | * | . * |
| 511 | * | . * |
| 512 | * 1/4 ...............................................* * * * * * * * * * * * |
| 513 | * | . . |
| 514 | * | . . |
| 515 | * | . . |
| 516 | * 0 +----------------------.-------------------------------.-------------> |
| 517 | * bdi_setpoint^ x_intercept^ |
| 518 | * |
| 519 | * The bdi control line won't drop below pos_ratio=1/4, so that bdi_dirty can |
| 520 | * be smoothly throttled down to normal if it starts high in situations like |
| 521 | * - start writing to a slow SD card and a fast disk at the same time. The SD |
| 522 | * card's bdi_dirty may rush to many times higher than bdi_setpoint. |
| 523 | * - the bdi dirty thresh drops quickly due to change of JBOD workload |
| 524 | */ |
| 525 | static unsigned long bdi_position_ratio(struct backing_dev_info *bdi, |
| 526 | unsigned long thresh, |
| 527 | unsigned long bg_thresh, |
| 528 | unsigned long dirty, |
| 529 | unsigned long bdi_thresh, |
| 530 | unsigned long bdi_dirty) |
| 531 | { |
| 532 | unsigned long write_bw = bdi->avg_write_bandwidth; |
| 533 | unsigned long freerun = dirty_freerun_ceiling(thresh, bg_thresh); |
| 534 | unsigned long limit = hard_dirty_limit(thresh); |
| 535 | unsigned long x_intercept; |
| 536 | unsigned long setpoint; /* dirty pages' target balance point */ |
| 537 | unsigned long bdi_setpoint; |
| 538 | unsigned long span; |
| 539 | long long pos_ratio; /* for scaling up/down the rate limit */ |
| 540 | long x; |
| 541 | |
| 542 | if (unlikely(dirty >= limit)) |
| 543 | return 0; |
| 544 | |
| 545 | /* |
| 546 | * global setpoint |
| 547 | * |
| 548 | * setpoint - dirty 3 |
| 549 | * f(dirty) := 1.0 + (----------------) |
| 550 | * limit - setpoint |
| 551 | * |
| 552 | * it's a 3rd order polynomial that subjects to |
| 553 | * |
| 554 | * (1) f(freerun) = 2.0 => rampup dirty_ratelimit reasonably fast |
| 555 | * (2) f(setpoint) = 1.0 => the balance point |
| 556 | * (3) f(limit) = 0 => the hard limit |
| 557 | * (4) df/dx <= 0 => negative feedback control |
| 558 | * (5) the closer to setpoint, the smaller |df/dx| (and the reverse) |
| 559 | * => fast response on large errors; small oscillation near setpoint |
| 560 | */ |
| 561 | setpoint = (freerun + limit) / 2; |
| 562 | x = div_s64((setpoint - dirty) << RATELIMIT_CALC_SHIFT, |
| 563 | limit - setpoint + 1); |
| 564 | pos_ratio = x; |
| 565 | pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT; |
| 566 | pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT; |
| 567 | pos_ratio += 1 << RATELIMIT_CALC_SHIFT; |
| 568 | |
| 569 | /* |
| 570 | * We have computed basic pos_ratio above based on global situation. If |
| 571 | * the bdi is over/under its share of dirty pages, we want to scale |
| 572 | * pos_ratio further down/up. That is done by the following mechanism. |
| 573 | */ |
| 574 | |
| 575 | /* |
| 576 | * bdi setpoint |
| 577 | * |
| 578 | * f(bdi_dirty) := 1.0 + k * (bdi_dirty - bdi_setpoint) |
| 579 | * |
| 580 | * x_intercept - bdi_dirty |
| 581 | * := -------------------------- |
| 582 | * x_intercept - bdi_setpoint |
| 583 | * |
| 584 | * The main bdi control line is a linear function that subjects to |
| 585 | * |
| 586 | * (1) f(bdi_setpoint) = 1.0 |
| 587 | * (2) k = - 1 / (8 * write_bw) (in single bdi case) |
| 588 | * or equally: x_intercept = bdi_setpoint + 8 * write_bw |
| 589 | * |
| 590 | * For single bdi case, the dirty pages are observed to fluctuate |
| 591 | * regularly within range |
| 592 | * [bdi_setpoint - write_bw/2, bdi_setpoint + write_bw/2] |
| 593 | * for various filesystems, where (2) can yield in a reasonable 12.5% |
| 594 | * fluctuation range for pos_ratio. |
| 595 | * |
| 596 | * For JBOD case, bdi_thresh (not bdi_dirty!) could fluctuate up to its |
| 597 | * own size, so move the slope over accordingly and choose a slope that |
| 598 | * yields 100% pos_ratio fluctuation on suddenly doubled bdi_thresh. |
| 599 | */ |
| 600 | if (unlikely(bdi_thresh > thresh)) |
| 601 | bdi_thresh = thresh; |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 602 | /* |
| 603 | * It's very possible that bdi_thresh is close to 0 not because the |
| 604 | * device is slow, but that it has remained inactive for long time. |
| 605 | * Honour such devices a reasonable good (hopefully IO efficient) |
| 606 | * threshold, so that the occasional writes won't be blocked and active |
| 607 | * writes can rampup the threshold quickly. |
| 608 | */ |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 609 | bdi_thresh = max(bdi_thresh, (limit - dirty) / 8); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 610 | /* |
| 611 | * scale global setpoint to bdi's: |
| 612 | * bdi_setpoint = setpoint * bdi_thresh / thresh |
| 613 | */ |
| 614 | x = div_u64((u64)bdi_thresh << 16, thresh + 1); |
| 615 | bdi_setpoint = setpoint * (u64)x >> 16; |
| 616 | /* |
| 617 | * Use span=(8*write_bw) in single bdi case as indicated by |
| 618 | * (thresh - bdi_thresh ~= 0) and transit to bdi_thresh in JBOD case. |
| 619 | * |
| 620 | * bdi_thresh thresh - bdi_thresh |
| 621 | * span = ---------- * (8 * write_bw) + ------------------- * bdi_thresh |
| 622 | * thresh thresh |
| 623 | */ |
| 624 | span = (thresh - bdi_thresh + 8 * write_bw) * (u64)x >> 16; |
| 625 | x_intercept = bdi_setpoint + span; |
| 626 | |
| 627 | if (bdi_dirty < x_intercept - span / 4) { |
Wu Fengguang | 50657fc | 2011-10-11 17:06:33 -0600 | [diff] [blame] | 628 | pos_ratio = div_u64(pos_ratio * (x_intercept - bdi_dirty), |
| 629 | x_intercept - bdi_setpoint + 1); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 630 | } else |
| 631 | pos_ratio /= 4; |
| 632 | |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 633 | /* |
| 634 | * bdi reserve area, safeguard against dirty pool underrun and disk idle |
| 635 | * It may push the desired control point of global dirty pages higher |
| 636 | * than setpoint. |
| 637 | */ |
| 638 | x_intercept = bdi_thresh / 2; |
| 639 | if (bdi_dirty < x_intercept) { |
Wu Fengguang | 50657fc | 2011-10-11 17:06:33 -0600 | [diff] [blame] | 640 | if (bdi_dirty > x_intercept / 8) |
| 641 | pos_ratio = div_u64(pos_ratio * x_intercept, bdi_dirty); |
| 642 | else |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 643 | pos_ratio *= 8; |
| 644 | } |
| 645 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 646 | return pos_ratio; |
| 647 | } |
| 648 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 649 | static void bdi_update_write_bandwidth(struct backing_dev_info *bdi, |
| 650 | unsigned long elapsed, |
| 651 | unsigned long written) |
| 652 | { |
| 653 | const unsigned long period = roundup_pow_of_two(3 * HZ); |
| 654 | unsigned long avg = bdi->avg_write_bandwidth; |
| 655 | unsigned long old = bdi->write_bandwidth; |
| 656 | u64 bw; |
| 657 | |
| 658 | /* |
| 659 | * bw = written * HZ / elapsed |
| 660 | * |
| 661 | * bw * elapsed + write_bandwidth * (period - elapsed) |
| 662 | * write_bandwidth = --------------------------------------------------- |
| 663 | * period |
| 664 | */ |
| 665 | bw = written - bdi->written_stamp; |
| 666 | bw *= HZ; |
| 667 | if (unlikely(elapsed > period)) { |
| 668 | do_div(bw, elapsed); |
| 669 | avg = bw; |
| 670 | goto out; |
| 671 | } |
| 672 | bw += (u64)bdi->write_bandwidth * (period - elapsed); |
| 673 | bw >>= ilog2(period); |
| 674 | |
| 675 | /* |
| 676 | * one more level of smoothing, for filtering out sudden spikes |
| 677 | */ |
| 678 | if (avg > old && old >= (unsigned long)bw) |
| 679 | avg -= (avg - old) >> 3; |
| 680 | |
| 681 | if (avg < old && old <= (unsigned long)bw) |
| 682 | avg += (old - avg) >> 3; |
| 683 | |
| 684 | out: |
| 685 | bdi->write_bandwidth = bw; |
| 686 | bdi->avg_write_bandwidth = avg; |
| 687 | } |
| 688 | |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 689 | /* |
| 690 | * The global dirtyable memory and dirty threshold could be suddenly knocked |
| 691 | * down by a large amount (eg. on the startup of KVM in a swapless system). |
| 692 | * This may throw the system into deep dirty exceeded state and throttle |
| 693 | * heavy/light dirtiers alike. To retain good responsiveness, maintain |
| 694 | * global_dirty_limit for tracking slowly down to the knocked down dirty |
| 695 | * threshold. |
| 696 | */ |
| 697 | static void update_dirty_limit(unsigned long thresh, unsigned long dirty) |
| 698 | { |
| 699 | unsigned long limit = global_dirty_limit; |
| 700 | |
| 701 | /* |
| 702 | * Follow up in one step. |
| 703 | */ |
| 704 | if (limit < thresh) { |
| 705 | limit = thresh; |
| 706 | goto update; |
| 707 | } |
| 708 | |
| 709 | /* |
| 710 | * Follow down slowly. Use the higher one as the target, because thresh |
| 711 | * may drop below dirty. This is exactly the reason to introduce |
| 712 | * global_dirty_limit which is guaranteed to lie above the dirty pages. |
| 713 | */ |
| 714 | thresh = max(thresh, dirty); |
| 715 | if (limit > thresh) { |
| 716 | limit -= (limit - thresh) >> 5; |
| 717 | goto update; |
| 718 | } |
| 719 | return; |
| 720 | update: |
| 721 | global_dirty_limit = limit; |
| 722 | } |
| 723 | |
| 724 | static void global_update_bandwidth(unsigned long thresh, |
| 725 | unsigned long dirty, |
| 726 | unsigned long now) |
| 727 | { |
| 728 | static DEFINE_SPINLOCK(dirty_lock); |
| 729 | static unsigned long update_time; |
| 730 | |
| 731 | /* |
| 732 | * check locklessly first to optimize away locking for the most time |
| 733 | */ |
| 734 | if (time_before(now, update_time + BANDWIDTH_INTERVAL)) |
| 735 | return; |
| 736 | |
| 737 | spin_lock(&dirty_lock); |
| 738 | if (time_after_eq(now, update_time + BANDWIDTH_INTERVAL)) { |
| 739 | update_dirty_limit(thresh, dirty); |
| 740 | update_time = now; |
| 741 | } |
| 742 | spin_unlock(&dirty_lock); |
| 743 | } |
| 744 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 745 | /* |
| 746 | * Maintain bdi->dirty_ratelimit, the base dirty throttle rate. |
| 747 | * |
| 748 | * Normal bdi tasks will be curbed at or below it in long term. |
| 749 | * Obviously it should be around (write_bw / N) when there are N dd tasks. |
| 750 | */ |
| 751 | static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi, |
| 752 | unsigned long thresh, |
| 753 | unsigned long bg_thresh, |
| 754 | unsigned long dirty, |
| 755 | unsigned long bdi_thresh, |
| 756 | unsigned long bdi_dirty, |
| 757 | unsigned long dirtied, |
| 758 | unsigned long elapsed) |
| 759 | { |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 760 | unsigned long freerun = dirty_freerun_ceiling(thresh, bg_thresh); |
| 761 | unsigned long limit = hard_dirty_limit(thresh); |
| 762 | unsigned long setpoint = (freerun + limit) / 2; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 763 | unsigned long write_bw = bdi->avg_write_bandwidth; |
| 764 | unsigned long dirty_ratelimit = bdi->dirty_ratelimit; |
| 765 | unsigned long dirty_rate; |
| 766 | unsigned long task_ratelimit; |
| 767 | unsigned long balanced_dirty_ratelimit; |
| 768 | unsigned long pos_ratio; |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 769 | unsigned long step; |
| 770 | unsigned long x; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 771 | |
| 772 | /* |
| 773 | * The dirty rate will match the writeout rate in long term, except |
| 774 | * when dirty pages are truncated by userspace or re-dirtied by FS. |
| 775 | */ |
| 776 | dirty_rate = (dirtied - bdi->dirtied_stamp) * HZ / elapsed; |
| 777 | |
| 778 | pos_ratio = bdi_position_ratio(bdi, thresh, bg_thresh, dirty, |
| 779 | bdi_thresh, bdi_dirty); |
| 780 | /* |
| 781 | * task_ratelimit reflects each dd's dirty rate for the past 200ms. |
| 782 | */ |
| 783 | task_ratelimit = (u64)dirty_ratelimit * |
| 784 | pos_ratio >> RATELIMIT_CALC_SHIFT; |
| 785 | task_ratelimit++; /* it helps rampup dirty_ratelimit from tiny values */ |
| 786 | |
| 787 | /* |
| 788 | * A linear estimation of the "balanced" throttle rate. The theory is, |
| 789 | * if there are N dd tasks, each throttled at task_ratelimit, the bdi's |
| 790 | * dirty_rate will be measured to be (N * task_ratelimit). So the below |
| 791 | * formula will yield the balanced rate limit (write_bw / N). |
| 792 | * |
| 793 | * Note that the expanded form is not a pure rate feedback: |
| 794 | * rate_(i+1) = rate_(i) * (write_bw / dirty_rate) (1) |
| 795 | * but also takes pos_ratio into account: |
| 796 | * rate_(i+1) = rate_(i) * (write_bw / dirty_rate) * pos_ratio (2) |
| 797 | * |
| 798 | * (1) is not realistic because pos_ratio also takes part in balancing |
| 799 | * the dirty rate. Consider the state |
| 800 | * pos_ratio = 0.5 (3) |
| 801 | * rate = 2 * (write_bw / N) (4) |
| 802 | * If (1) is used, it will stuck in that state! Because each dd will |
| 803 | * be throttled at |
| 804 | * task_ratelimit = pos_ratio * rate = (write_bw / N) (5) |
| 805 | * yielding |
| 806 | * dirty_rate = N * task_ratelimit = write_bw (6) |
| 807 | * put (6) into (1) we get |
| 808 | * rate_(i+1) = rate_(i) (7) |
| 809 | * |
| 810 | * So we end up using (2) to always keep |
| 811 | * rate_(i+1) ~= (write_bw / N) (8) |
| 812 | * regardless of the value of pos_ratio. As long as (8) is satisfied, |
| 813 | * pos_ratio is able to drive itself to 1.0, which is not only where |
| 814 | * the dirty count meet the setpoint, but also where the slope of |
| 815 | * pos_ratio is most flat and hence task_ratelimit is least fluctuated. |
| 816 | */ |
| 817 | balanced_dirty_ratelimit = div_u64((u64)task_ratelimit * write_bw, |
| 818 | dirty_rate | 1); |
| 819 | |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 820 | /* |
| 821 | * We could safely do this and return immediately: |
| 822 | * |
| 823 | * bdi->dirty_ratelimit = balanced_dirty_ratelimit; |
| 824 | * |
| 825 | * However to get a more stable dirty_ratelimit, the below elaborated |
| 826 | * code makes use of task_ratelimit to filter out sigular points and |
| 827 | * limit the step size. |
| 828 | * |
| 829 | * The below code essentially only uses the relative value of |
| 830 | * |
| 831 | * task_ratelimit - dirty_ratelimit |
| 832 | * = (pos_ratio - 1) * dirty_ratelimit |
| 833 | * |
| 834 | * which reflects the direction and size of dirty position error. |
| 835 | */ |
| 836 | |
| 837 | /* |
| 838 | * dirty_ratelimit will follow balanced_dirty_ratelimit iff |
| 839 | * task_ratelimit is on the same side of dirty_ratelimit, too. |
| 840 | * For example, when |
| 841 | * - dirty_ratelimit > balanced_dirty_ratelimit |
| 842 | * - dirty_ratelimit > task_ratelimit (dirty pages are above setpoint) |
| 843 | * lowering dirty_ratelimit will help meet both the position and rate |
| 844 | * control targets. Otherwise, don't update dirty_ratelimit if it will |
| 845 | * only help meet the rate target. After all, what the users ultimately |
| 846 | * feel and care are stable dirty rate and small position error. |
| 847 | * |
| 848 | * |task_ratelimit - dirty_ratelimit| is used to limit the step size |
| 849 | * and filter out the sigular points of balanced_dirty_ratelimit. Which |
| 850 | * keeps jumping around randomly and can even leap far away at times |
| 851 | * due to the small 200ms estimation period of dirty_rate (we want to |
| 852 | * keep that period small to reduce time lags). |
| 853 | */ |
| 854 | step = 0; |
| 855 | if (dirty < setpoint) { |
| 856 | x = min(bdi->balanced_dirty_ratelimit, |
| 857 | min(balanced_dirty_ratelimit, task_ratelimit)); |
| 858 | if (dirty_ratelimit < x) |
| 859 | step = x - dirty_ratelimit; |
| 860 | } else { |
| 861 | x = max(bdi->balanced_dirty_ratelimit, |
| 862 | max(balanced_dirty_ratelimit, task_ratelimit)); |
| 863 | if (dirty_ratelimit > x) |
| 864 | step = dirty_ratelimit - x; |
| 865 | } |
| 866 | |
| 867 | /* |
| 868 | * Don't pursue 100% rate matching. It's impossible since the balanced |
| 869 | * rate itself is constantly fluctuating. So decrease the track speed |
| 870 | * when it gets close to the target. Helps eliminate pointless tremors. |
| 871 | */ |
| 872 | step >>= dirty_ratelimit / (2 * step + 1); |
| 873 | /* |
| 874 | * Limit the tracking speed to avoid overshooting. |
| 875 | */ |
| 876 | step = (step + 7) / 8; |
| 877 | |
| 878 | if (dirty_ratelimit < balanced_dirty_ratelimit) |
| 879 | dirty_ratelimit += step; |
| 880 | else |
| 881 | dirty_ratelimit -= step; |
| 882 | |
| 883 | bdi->dirty_ratelimit = max(dirty_ratelimit, 1UL); |
| 884 | bdi->balanced_dirty_ratelimit = balanced_dirty_ratelimit; |
Wu Fengguang | b48c104 | 2011-03-02 17:22:49 -0600 | [diff] [blame] | 885 | |
| 886 | trace_bdi_dirty_ratelimit(bdi, dirty_rate, task_ratelimit); |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 887 | } |
| 888 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 889 | void __bdi_update_bandwidth(struct backing_dev_info *bdi, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 890 | unsigned long thresh, |
Wu Fengguang | af6a311 | 2011-10-03 20:46:17 -0600 | [diff] [blame] | 891 | unsigned long bg_thresh, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 892 | unsigned long dirty, |
| 893 | unsigned long bdi_thresh, |
| 894 | unsigned long bdi_dirty, |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 895 | unsigned long start_time) |
| 896 | { |
| 897 | unsigned long now = jiffies; |
| 898 | unsigned long elapsed = now - bdi->bw_time_stamp; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 899 | unsigned long dirtied; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 900 | unsigned long written; |
| 901 | |
| 902 | /* |
| 903 | * rate-limit, only update once every 200ms. |
| 904 | */ |
| 905 | if (elapsed < BANDWIDTH_INTERVAL) |
| 906 | return; |
| 907 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 908 | dirtied = percpu_counter_read(&bdi->bdi_stat[BDI_DIRTIED]); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 909 | written = percpu_counter_read(&bdi->bdi_stat[BDI_WRITTEN]); |
| 910 | |
| 911 | /* |
| 912 | * Skip quiet periods when disk bandwidth is under-utilized. |
| 913 | * (at least 1s idle time between two flusher runs) |
| 914 | */ |
| 915 | if (elapsed > HZ && time_before(bdi->bw_time_stamp, start_time)) |
| 916 | goto snapshot; |
| 917 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 918 | if (thresh) { |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 919 | global_update_bandwidth(thresh, dirty, now); |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 920 | bdi_update_dirty_ratelimit(bdi, thresh, bg_thresh, dirty, |
| 921 | bdi_thresh, bdi_dirty, |
| 922 | dirtied, elapsed); |
| 923 | } |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 924 | bdi_update_write_bandwidth(bdi, elapsed, written); |
| 925 | |
| 926 | snapshot: |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 927 | bdi->dirtied_stamp = dirtied; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 928 | bdi->written_stamp = written; |
| 929 | bdi->bw_time_stamp = now; |
| 930 | } |
| 931 | |
| 932 | static void bdi_update_bandwidth(struct backing_dev_info *bdi, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 933 | unsigned long thresh, |
Wu Fengguang | af6a311 | 2011-10-03 20:46:17 -0600 | [diff] [blame] | 934 | unsigned long bg_thresh, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 935 | unsigned long dirty, |
| 936 | unsigned long bdi_thresh, |
| 937 | unsigned long bdi_dirty, |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 938 | unsigned long start_time) |
| 939 | { |
| 940 | if (time_is_after_eq_jiffies(bdi->bw_time_stamp + BANDWIDTH_INTERVAL)) |
| 941 | return; |
| 942 | spin_lock(&bdi->wb.list_lock); |
Wu Fengguang | af6a311 | 2011-10-03 20:46:17 -0600 | [diff] [blame] | 943 | __bdi_update_bandwidth(bdi, thresh, bg_thresh, dirty, |
| 944 | bdi_thresh, bdi_dirty, start_time); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 945 | spin_unlock(&bdi->wb.list_lock); |
| 946 | } |
| 947 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 948 | /* |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 949 | * After a task dirtied this many pages, balance_dirty_pages_ratelimited_nr() |
| 950 | * will look to see if it needs to start dirty throttling. |
| 951 | * |
| 952 | * If dirty_poll_interval is too low, big NUMA machines will call the expensive |
| 953 | * global_page_state() too often. So scale it near-sqrt to the safety margin |
| 954 | * (the number of pages we may dirty without exceeding the dirty limits). |
| 955 | */ |
| 956 | static unsigned long dirty_poll_interval(unsigned long dirty, |
| 957 | unsigned long thresh) |
| 958 | { |
| 959 | if (thresh > dirty) |
| 960 | return 1UL << (ilog2(thresh - dirty) >> 1); |
| 961 | |
| 962 | return 1; |
| 963 | } |
| 964 | |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 965 | static unsigned long bdi_max_pause(struct backing_dev_info *bdi, |
| 966 | unsigned long bdi_dirty) |
| 967 | { |
| 968 | unsigned long bw = bdi->avg_write_bandwidth; |
| 969 | unsigned long hi = ilog2(bw); |
| 970 | unsigned long lo = ilog2(bdi->dirty_ratelimit); |
| 971 | unsigned long t; |
| 972 | |
| 973 | /* target for 20ms max pause on 1-dd case */ |
| 974 | t = HZ / 50; |
| 975 | |
| 976 | /* |
| 977 | * Scale up pause time for concurrent dirtiers in order to reduce CPU |
| 978 | * overheads. |
| 979 | * |
| 980 | * (N * 20ms) on 2^N concurrent tasks. |
| 981 | */ |
| 982 | if (hi > lo) |
| 983 | t += (hi - lo) * (20 * HZ) / 1024; |
| 984 | |
| 985 | /* |
| 986 | * Limit pause time for small memory systems. If sleeping for too long |
| 987 | * time, a small pool of dirty/writeback pages may go empty and disk go |
| 988 | * idle. |
| 989 | * |
| 990 | * 8 serves as the safety ratio. |
| 991 | */ |
Wu Fengguang | 82e230a | 2011-12-02 18:21:51 -0600 | [diff] [blame] | 992 | t = min(t, bdi_dirty * HZ / (8 * bw + 1)); |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 993 | |
| 994 | /* |
| 995 | * The pause time will be settled within range (max_pause/4, max_pause). |
| 996 | * Apply a minimal value of 4 to get a non-zero max_pause/4. |
| 997 | */ |
| 998 | return clamp_val(t, 4, MAX_PAUSE); |
| 999 | } |
| 1000 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1001 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1002 | * balance_dirty_pages() must be called by processes which are generating dirty |
| 1003 | * data. It looks at the number of dirty pages in the machine and will force |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1004 | * the caller to wait once crossing the (background_thresh + dirty_thresh) / 2. |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 1005 | * If we're over `background_thresh' then the writeback threads are woken to |
| 1006 | * perform some writeout. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1007 | */ |
Wu Fengguang | 3a2e9a5 | 2009-09-23 21:56:00 +0800 | [diff] [blame] | 1008 | static void balance_dirty_pages(struct address_space *mapping, |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1009 | unsigned long pages_dirtied) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1010 | { |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1011 | unsigned long nr_reclaimable; /* = file_dirty + unstable_nfs */ |
| 1012 | unsigned long bdi_reclaimable; |
Wu Fengguang | 7762741 | 2010-09-12 13:34:05 -0600 | [diff] [blame] | 1013 | unsigned long nr_dirty; /* = file_dirty + writeback + unstable_nfs */ |
| 1014 | unsigned long bdi_dirty; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1015 | unsigned long freerun; |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 1016 | unsigned long background_thresh; |
| 1017 | unsigned long dirty_thresh; |
| 1018 | unsigned long bdi_thresh; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1019 | long pause = 0; |
Wu Fengguang | 50657fc | 2011-10-11 17:06:33 -0600 | [diff] [blame] | 1020 | long uninitialized_var(max_pause); |
Wu Fengguang | e50e372 | 2010-08-11 14:17:37 -0700 | [diff] [blame] | 1021 | bool dirty_exceeded = false; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1022 | unsigned long task_ratelimit; |
Wu Fengguang | 50657fc | 2011-10-11 17:06:33 -0600 | [diff] [blame] | 1023 | unsigned long uninitialized_var(dirty_ratelimit); |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1024 | unsigned long pos_ratio; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1025 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1026 | unsigned long start_time = jiffies; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1027 | |
| 1028 | for (;;) { |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1029 | /* |
| 1030 | * Unstable writes are a feature of certain networked |
| 1031 | * filesystems (i.e. NFS) in which data may have been |
| 1032 | * written to the server's write cache, but has not yet |
| 1033 | * been flushed to permanent storage. |
| 1034 | */ |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1035 | nr_reclaimable = global_page_state(NR_FILE_DIRTY) + |
| 1036 | global_page_state(NR_UNSTABLE_NFS); |
Wu Fengguang | 7762741 | 2010-09-12 13:34:05 -0600 | [diff] [blame] | 1037 | nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1038 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1039 | global_dirty_limits(&background_thresh, &dirty_thresh); |
| 1040 | |
| 1041 | /* |
| 1042 | * Throttle it only when the background writeback cannot |
| 1043 | * catch-up. This avoids (excessively) small writeouts |
| 1044 | * when the bdi limits are ramping up. |
| 1045 | */ |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1046 | freerun = dirty_freerun_ceiling(dirty_thresh, |
| 1047 | background_thresh); |
| 1048 | if (nr_dirty <= freerun) |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1049 | break; |
| 1050 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1051 | if (unlikely(!writeback_in_progress(bdi))) |
| 1052 | bdi_start_background_writeback(bdi); |
| 1053 | |
| 1054 | /* |
| 1055 | * bdi_thresh is not treated as some limiting factor as |
| 1056 | * dirty_thresh, due to reasons |
| 1057 | * - in JBOD setup, bdi_thresh can fluctuate a lot |
| 1058 | * - in a system with HDD and USB key, the USB key may somehow |
| 1059 | * go into state (bdi_dirty >> bdi_thresh) either because |
| 1060 | * bdi_dirty starts high, or because bdi_thresh drops low. |
| 1061 | * In this case we don't want to hard throttle the USB key |
| 1062 | * dirtiers for 100 seconds until bdi_dirty drops under |
| 1063 | * bdi_thresh. Instead the auxiliary bdi control line in |
| 1064 | * bdi_position_ratio() will let the dirtier task progress |
| 1065 | * at some rate <= (write_bw / 2) for bringing down bdi_dirty. |
| 1066 | */ |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1067 | bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1068 | |
Wu Fengguang | e50e372 | 2010-08-11 14:17:37 -0700 | [diff] [blame] | 1069 | /* |
| 1070 | * In order to avoid the stacked BDI deadlock we need |
| 1071 | * to ensure we accurately count the 'dirty' pages when |
| 1072 | * the threshold is low. |
| 1073 | * |
| 1074 | * Otherwise it would be possible to get thresh+n pages |
| 1075 | * reported dirty, even though there are thresh-m pages |
| 1076 | * actually dirty; with m+n sitting in the percpu |
| 1077 | * deltas. |
| 1078 | */ |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1079 | if (bdi_thresh < 2 * bdi_stat_error(bdi)) { |
| 1080 | bdi_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE); |
| 1081 | bdi_dirty = bdi_reclaimable + |
Wu Fengguang | 7762741 | 2010-09-12 13:34:05 -0600 | [diff] [blame] | 1082 | bdi_stat_sum(bdi, BDI_WRITEBACK); |
Wu Fengguang | e50e372 | 2010-08-11 14:17:37 -0700 | [diff] [blame] | 1083 | } else { |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1084 | bdi_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE); |
| 1085 | bdi_dirty = bdi_reclaimable + |
Wu Fengguang | 7762741 | 2010-09-12 13:34:05 -0600 | [diff] [blame] | 1086 | bdi_stat(bdi, BDI_WRITEBACK); |
Wu Fengguang | e50e372 | 2010-08-11 14:17:37 -0700 | [diff] [blame] | 1087 | } |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1088 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1089 | dirty_exceeded = (bdi_dirty > bdi_thresh) || |
Wu Fengguang | 7762741 | 2010-09-12 13:34:05 -0600 | [diff] [blame] | 1090 | (nr_dirty > dirty_thresh); |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1091 | if (dirty_exceeded && !bdi->dirty_exceeded) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1092 | bdi->dirty_exceeded = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1093 | |
Wu Fengguang | af6a311 | 2011-10-03 20:46:17 -0600 | [diff] [blame] | 1094 | bdi_update_bandwidth(bdi, dirty_thresh, background_thresh, |
| 1095 | nr_dirty, bdi_thresh, bdi_dirty, |
| 1096 | start_time); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1097 | |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1098 | max_pause = bdi_max_pause(bdi, bdi_dirty); |
| 1099 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1100 | dirty_ratelimit = bdi->dirty_ratelimit; |
| 1101 | pos_ratio = bdi_position_ratio(bdi, dirty_thresh, |
| 1102 | background_thresh, nr_dirty, |
| 1103 | bdi_thresh, bdi_dirty); |
Wu Fengguang | 3a73dbb | 2011-11-07 19:19:28 +0800 | [diff] [blame] | 1104 | task_ratelimit = ((u64)dirty_ratelimit * pos_ratio) >> |
| 1105 | RATELIMIT_CALC_SHIFT; |
| 1106 | if (unlikely(task_ratelimit == 0)) { |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1107 | pause = max_pause; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1108 | goto pause; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1109 | } |
Wu Fengguang | 3a73dbb | 2011-11-07 19:19:28 +0800 | [diff] [blame] | 1110 | pause = HZ * pages_dirtied / task_ratelimit; |
Wu Fengguang | 57fc978 | 2011-06-11 19:32:32 -0600 | [diff] [blame] | 1111 | if (unlikely(pause <= 0)) { |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1112 | trace_balance_dirty_pages(bdi, |
| 1113 | dirty_thresh, |
| 1114 | background_thresh, |
| 1115 | nr_dirty, |
| 1116 | bdi_thresh, |
| 1117 | bdi_dirty, |
| 1118 | dirty_ratelimit, |
| 1119 | task_ratelimit, |
| 1120 | pages_dirtied, |
| 1121 | pause, |
| 1122 | start_time); |
Wu Fengguang | 57fc978 | 2011-06-11 19:32:32 -0600 | [diff] [blame] | 1123 | pause = 1; /* avoid resetting nr_dirtied_pause below */ |
| 1124 | break; |
| 1125 | } |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1126 | pause = min(pause, max_pause); |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1127 | |
| 1128 | pause: |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1129 | trace_balance_dirty_pages(bdi, |
| 1130 | dirty_thresh, |
| 1131 | background_thresh, |
| 1132 | nr_dirty, |
| 1133 | bdi_thresh, |
| 1134 | bdi_dirty, |
| 1135 | dirty_ratelimit, |
| 1136 | task_ratelimit, |
| 1137 | pages_dirtied, |
| 1138 | pause, |
| 1139 | start_time); |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1140 | __set_current_state(TASK_KILLABLE); |
Wu Fengguang | d25105e | 2009-10-09 12:40:42 +0200 | [diff] [blame] | 1141 | io_schedule_timeout(pause); |
Jens Axboe | 87c6a9b | 2009-09-17 19:59:14 +0200 | [diff] [blame] | 1142 | |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1143 | /* |
Wu Fengguang | 1df6471 | 2011-11-13 19:47:32 -0600 | [diff] [blame] | 1144 | * This is typically equal to (nr_dirty < dirty_thresh) and can |
| 1145 | * also keep "1000+ dd on a slow USB stick" under control. |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1146 | */ |
Wu Fengguang | 1df6471 | 2011-11-13 19:47:32 -0600 | [diff] [blame] | 1147 | if (task_ratelimit) |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1148 | break; |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1149 | |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1150 | /* |
| 1151 | * In the case of an unresponding NFS server and the NFS dirty |
| 1152 | * pages exceeds dirty_thresh, give the other good bdi's a pipe |
| 1153 | * to go through, so that tasks on them still remain responsive. |
| 1154 | * |
| 1155 | * In theory 1 page is enough to keep the comsumer-producer |
| 1156 | * pipe going: the flusher cleans 1 page => the task dirties 1 |
| 1157 | * more page. However bdi_dirty has accounting errors. So use |
| 1158 | * the larger and more IO friendly bdi_stat_error. |
| 1159 | */ |
| 1160 | if (bdi_dirty <= bdi_stat_error(bdi)) |
| 1161 | break; |
| 1162 | |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1163 | if (fatal_signal_pending(current)) |
| 1164 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1165 | } |
| 1166 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1167 | if (!dirty_exceeded && bdi->dirty_exceeded) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1168 | bdi->dirty_exceeded = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1169 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1170 | current->nr_dirtied = 0; |
Wu Fengguang | 57fc978 | 2011-06-11 19:32:32 -0600 | [diff] [blame] | 1171 | if (pause == 0) { /* in freerun area */ |
| 1172 | current->nr_dirtied_pause = |
| 1173 | dirty_poll_interval(nr_dirty, dirty_thresh); |
| 1174 | } else if (pause <= max_pause / 4 && |
| 1175 | pages_dirtied >= current->nr_dirtied_pause) { |
| 1176 | current->nr_dirtied_pause = clamp_val( |
| 1177 | dirty_ratelimit * (max_pause / 2) / HZ, |
| 1178 | pages_dirtied + pages_dirtied / 8, |
| 1179 | pages_dirtied * 4); |
| 1180 | } else if (pause >= max_pause) { |
| 1181 | current->nr_dirtied_pause = 1 | clamp_val( |
| 1182 | dirty_ratelimit * (max_pause / 2) / HZ, |
| 1183 | pages_dirtied / 4, |
| 1184 | pages_dirtied - pages_dirtied / 8); |
| 1185 | } |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1186 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1187 | if (writeback_in_progress(bdi)) |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 1188 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1189 | |
| 1190 | /* |
| 1191 | * In laptop mode, we wait until hitting the higher threshold before |
| 1192 | * starting background writeout, and then write out all the way down |
| 1193 | * to the lower threshold. So slow writers cause minimal disk activity. |
| 1194 | * |
| 1195 | * In normal mode, we start background writeout at the lower |
| 1196 | * background_thresh, to keep the amount of dirty memory low. |
| 1197 | */ |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1198 | if (laptop_mode) |
| 1199 | return; |
| 1200 | |
| 1201 | if (nr_reclaimable > background_thresh) |
Christoph Hellwig | c544419 | 2010-06-08 18:15:15 +0200 | [diff] [blame] | 1202 | bdi_start_background_writeback(bdi); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1203 | } |
| 1204 | |
Peter Zijlstra | a200ee1 | 2007-10-08 18:54:37 +0200 | [diff] [blame] | 1205 | void set_page_dirty_balance(struct page *page, int page_mkwrite) |
Peter Zijlstra | edc79b2 | 2006-09-25 23:30:58 -0700 | [diff] [blame] | 1206 | { |
Peter Zijlstra | a200ee1 | 2007-10-08 18:54:37 +0200 | [diff] [blame] | 1207 | if (set_page_dirty(page) || page_mkwrite) { |
Peter Zijlstra | edc79b2 | 2006-09-25 23:30:58 -0700 | [diff] [blame] | 1208 | struct address_space *mapping = page_mapping(page); |
| 1209 | |
| 1210 | if (mapping) |
| 1211 | balance_dirty_pages_ratelimited(mapping); |
| 1212 | } |
| 1213 | } |
| 1214 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1215 | static DEFINE_PER_CPU(int, bdp_ratelimits); |
Tejun Heo | 245b2e7 | 2009-06-24 15:13:48 +0900 | [diff] [blame] | 1216 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1217 | /** |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1218 | * balance_dirty_pages_ratelimited_nr - balance dirty memory state |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 1219 | * @mapping: address_space which was dirtied |
Martin Waitz | a580290 | 2006-04-02 13:59:55 +0200 | [diff] [blame] | 1220 | * @nr_pages_dirtied: number of pages which the caller has just dirtied |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1221 | * |
| 1222 | * Processes which are dirtying memory should call in here once for each page |
| 1223 | * which was newly dirtied. The function will periodically check the system's |
| 1224 | * dirty state and will initiate writeback if needed. |
| 1225 | * |
| 1226 | * On really big machines, get_writeback_state is expensive, so try to avoid |
| 1227 | * calling it too often (ratelimiting). But once we're over the dirty memory |
| 1228 | * limit we decrease the ratelimiting by a lot, to prevent individual processes |
| 1229 | * from overshooting the limit by (ratelimit_pages) each. |
| 1230 | */ |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1231 | void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, |
| 1232 | unsigned long nr_pages_dirtied) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1233 | { |
Wu Fengguang | 36715ce | 2011-06-11 17:53:57 -0600 | [diff] [blame] | 1234 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1235 | int ratelimit; |
| 1236 | int *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1237 | |
Wu Fengguang | 36715ce | 2011-06-11 17:53:57 -0600 | [diff] [blame] | 1238 | if (!bdi_cap_account_dirty(bdi)) |
| 1239 | return; |
| 1240 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1241 | ratelimit = current->nr_dirtied_pause; |
| 1242 | if (bdi->dirty_exceeded) |
| 1243 | ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1244 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1245 | current->nr_dirtied += nr_pages_dirtied; |
| 1246 | |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1247 | preempt_disable(); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1248 | /* |
| 1249 | * This prevents one CPU to accumulate too many dirtied pages without |
| 1250 | * calling into balance_dirty_pages(), which can happen when there are |
| 1251 | * 1000+ tasks, all of them start dirtying pages at exactly the same |
| 1252 | * time, hence all honoured too large initial task->nr_dirtied_pause. |
| 1253 | */ |
Tejun Heo | 245b2e7 | 2009-06-24 15:13:48 +0900 | [diff] [blame] | 1254 | p = &__get_cpu_var(bdp_ratelimits); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1255 | if (unlikely(current->nr_dirtied >= ratelimit)) |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1256 | *p = 0; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1257 | else { |
| 1258 | *p += nr_pages_dirtied; |
| 1259 | if (unlikely(*p >= ratelimit_pages)) { |
| 1260 | *p = 0; |
| 1261 | ratelimit = 0; |
| 1262 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1263 | } |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1264 | preempt_enable(); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1265 | |
| 1266 | if (unlikely(current->nr_dirtied >= ratelimit)) |
| 1267 | balance_dirty_pages(mapping, current->nr_dirtied); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1268 | } |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1269 | EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1270 | |
Andrew Morton | 232ea4d | 2007-02-28 20:13:21 -0800 | [diff] [blame] | 1271 | void throttle_vm_writeout(gfp_t gfp_mask) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1272 | { |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 1273 | unsigned long background_thresh; |
| 1274 | unsigned long dirty_thresh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1275 | |
| 1276 | for ( ; ; ) { |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1277 | global_dirty_limits(&background_thresh, &dirty_thresh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1278 | |
| 1279 | /* |
| 1280 | * Boost the allowable dirty threshold a bit for page |
| 1281 | * allocators so they don't get DoS'ed by heavy writers |
| 1282 | */ |
| 1283 | dirty_thresh += dirty_thresh / 10; /* wheeee... */ |
| 1284 | |
Christoph Lameter | c24f21b | 2006-06-30 01:55:42 -0700 | [diff] [blame] | 1285 | if (global_page_state(NR_UNSTABLE_NFS) + |
| 1286 | global_page_state(NR_WRITEBACK) <= dirty_thresh) |
| 1287 | break; |
Jens Axboe | 8aa7e84 | 2009-07-09 14:52:32 +0200 | [diff] [blame] | 1288 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
Fengguang Wu | 369f238 | 2007-10-16 23:30:45 -0700 | [diff] [blame] | 1289 | |
| 1290 | /* |
| 1291 | * The caller might hold locks which can prevent IO completion |
| 1292 | * or progress in the filesystem. So we cannot just sit here |
| 1293 | * waiting for IO to complete. |
| 1294 | */ |
| 1295 | if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) |
| 1296 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1297 | } |
| 1298 | } |
| 1299 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1300 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1301 | * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs |
| 1302 | */ |
| 1303 | int dirty_writeback_centisecs_handler(ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 1304 | void __user *buffer, size_t *length, loff_t *ppos) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1305 | { |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 1306 | proc_dointvec(table, write, buffer, length, ppos); |
Jens Axboe | 6423104 | 2010-05-21 20:00:35 +0200 | [diff] [blame] | 1307 | bdi_arm_supers_timer(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1308 | return 0; |
| 1309 | } |
| 1310 | |
Jens Axboe | c2c4986 | 2010-05-20 09:18:47 +0200 | [diff] [blame] | 1311 | #ifdef CONFIG_BLOCK |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1312 | void laptop_mode_timer_fn(unsigned long data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1313 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1314 | struct request_queue *q = (struct request_queue *)data; |
| 1315 | int nr_pages = global_page_state(NR_FILE_DIRTY) + |
| 1316 | global_page_state(NR_UNSTABLE_NFS); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1317 | |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1318 | /* |
| 1319 | * We want to write everything out, not just down to the dirty |
| 1320 | * threshold |
| 1321 | */ |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1322 | if (bdi_has_dirty_io(&q->backing_dev_info)) |
Curt Wohlgemuth | 0e175a1 | 2011-10-07 21:54:10 -0600 | [diff] [blame] | 1323 | bdi_start_writeback(&q->backing_dev_info, nr_pages, |
| 1324 | WB_REASON_LAPTOP_TIMER); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1325 | } |
| 1326 | |
| 1327 | /* |
| 1328 | * We've spun up the disk and we're in laptop mode: schedule writeback |
| 1329 | * of all dirty data a few seconds from now. If the flush is already scheduled |
| 1330 | * then push it back - the user is still using the disk. |
| 1331 | */ |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1332 | void laptop_io_completion(struct backing_dev_info *info) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1333 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1334 | mod_timer(&info->laptop_mode_wb_timer, jiffies + laptop_mode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1335 | } |
| 1336 | |
| 1337 | /* |
| 1338 | * We're in laptop mode and we've just synced. The sync's writes will have |
| 1339 | * caused another writeback to be scheduled by laptop_io_completion. |
| 1340 | * Nothing needs to be written back anymore, so we unschedule the writeback. |
| 1341 | */ |
| 1342 | void laptop_sync_completion(void) |
| 1343 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1344 | struct backing_dev_info *bdi; |
| 1345 | |
| 1346 | rcu_read_lock(); |
| 1347 | |
| 1348 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) |
| 1349 | del_timer(&bdi->laptop_mode_wb_timer); |
| 1350 | |
| 1351 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1352 | } |
Jens Axboe | c2c4986 | 2010-05-20 09:18:47 +0200 | [diff] [blame] | 1353 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1354 | |
| 1355 | /* |
| 1356 | * If ratelimit_pages is too high then we can get into dirty-data overload |
| 1357 | * if a large number of processes all perform writes at the same time. |
| 1358 | * If it is too low then SMP machines will call the (expensive) |
| 1359 | * get_writeback_state too often. |
| 1360 | * |
| 1361 | * Here we set ratelimit_pages to a level which ensures that when all CPUs are |
| 1362 | * dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1363 | * thresholds. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1364 | */ |
| 1365 | |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 1366 | void writeback_set_ratelimit(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1367 | { |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1368 | unsigned long background_thresh; |
| 1369 | unsigned long dirty_thresh; |
| 1370 | global_dirty_limits(&background_thresh, &dirty_thresh); |
| 1371 | ratelimit_pages = dirty_thresh / (num_online_cpus() * 32); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1372 | if (ratelimit_pages < 16) |
| 1373 | ratelimit_pages = 16; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1374 | } |
| 1375 | |
Chandra Seetharaman | 26c2143 | 2006-06-27 02:54:10 -0700 | [diff] [blame] | 1376 | static int __cpuinit |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1377 | ratelimit_handler(struct notifier_block *self, unsigned long u, void *v) |
| 1378 | { |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 1379 | writeback_set_ratelimit(); |
Paul E. McKenney | aa0f030 | 2007-02-10 01:46:37 -0800 | [diff] [blame] | 1380 | return NOTIFY_DONE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1381 | } |
| 1382 | |
Chandra Seetharaman | 74b85f3 | 2006-06-27 02:54:09 -0700 | [diff] [blame] | 1383 | static struct notifier_block __cpuinitdata ratelimit_nb = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1384 | .notifier_call = ratelimit_handler, |
| 1385 | .next = NULL, |
| 1386 | }; |
| 1387 | |
| 1388 | /* |
Linus Torvalds | dc6e29d | 2007-01-29 16:37:38 -0800 | [diff] [blame] | 1389 | * Called early on to tune the page writeback dirty limits. |
| 1390 | * |
| 1391 | * We used to scale dirty pages according to how total memory |
| 1392 | * related to pages that could be allocated for buffers (by |
| 1393 | * comparing nr_free_buffer_pages() to vm_total_pages. |
| 1394 | * |
| 1395 | * However, that was when we used "dirty_ratio" to scale with |
| 1396 | * all memory, and we don't do that any more. "dirty_ratio" |
| 1397 | * is now applied to total non-HIGHPAGE memory (by subtracting |
| 1398 | * totalhigh_pages from vm_total_pages), and as such we can't |
| 1399 | * get into the old insane situation any more where we had |
| 1400 | * large amounts of dirty pages compared to a small amount of |
| 1401 | * non-HIGHMEM memory. |
| 1402 | * |
| 1403 | * But we might still want to scale the dirty_ratio by how |
| 1404 | * much memory the box has.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1405 | */ |
| 1406 | void __init page_writeback_init(void) |
| 1407 | { |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1408 | int shift; |
| 1409 | |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 1410 | writeback_set_ratelimit(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1411 | register_cpu_notifier(&ratelimit_nb); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1412 | |
| 1413 | shift = calc_period_shift(); |
| 1414 | prop_descriptor_init(&vm_completions, shift); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1415 | } |
| 1416 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1417 | /** |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1418 | * tag_pages_for_writeback - tag pages to be written by write_cache_pages |
| 1419 | * @mapping: address space structure to write |
| 1420 | * @start: starting page index |
| 1421 | * @end: ending page index (inclusive) |
| 1422 | * |
| 1423 | * This function scans the page range from @start to @end (inclusive) and tags |
| 1424 | * all pages that have DIRTY tag set with a special TOWRITE tag. The idea is |
| 1425 | * that write_cache_pages (or whoever calls this function) will then use |
| 1426 | * TOWRITE tag to identify pages eligible for writeback. This mechanism is |
| 1427 | * used to avoid livelocking of writeback by a process steadily creating new |
| 1428 | * dirty pages in the file (thus it is important for this function to be quick |
| 1429 | * so that it can tag pages faster than a dirtying process can create them). |
| 1430 | */ |
| 1431 | /* |
| 1432 | * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce tree_lock latency. |
| 1433 | */ |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1434 | void tag_pages_for_writeback(struct address_space *mapping, |
| 1435 | pgoff_t start, pgoff_t end) |
| 1436 | { |
Randy Dunlap | 3c111a0 | 2010-08-11 14:17:30 -0700 | [diff] [blame] | 1437 | #define WRITEBACK_TAG_BATCH 4096 |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1438 | unsigned long tagged; |
| 1439 | |
| 1440 | do { |
| 1441 | spin_lock_irq(&mapping->tree_lock); |
| 1442 | tagged = radix_tree_range_tag_if_tagged(&mapping->page_tree, |
| 1443 | &start, end, WRITEBACK_TAG_BATCH, |
| 1444 | PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE); |
| 1445 | spin_unlock_irq(&mapping->tree_lock); |
| 1446 | WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH); |
| 1447 | cond_resched(); |
Jan Kara | d5ed3a4 | 2010-08-19 14:13:33 -0700 | [diff] [blame] | 1448 | /* We check 'start' to handle wrapping when end == ~0UL */ |
| 1449 | } while (tagged >= WRITEBACK_TAG_BATCH && start); |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1450 | } |
| 1451 | EXPORT_SYMBOL(tag_pages_for_writeback); |
| 1452 | |
| 1453 | /** |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1454 | * write_cache_pages - walk the list of dirty pages of the given address space and write all of them. |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1455 | * @mapping: address space structure to write |
| 1456 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1457 | * @writepage: function called for each page |
| 1458 | * @data: data passed to writepage function |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1459 | * |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1460 | * If a page is already under I/O, write_cache_pages() skips it, even |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1461 | * if it's dirty. This is desirable behaviour for memory-cleaning writeback, |
| 1462 | * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() |
| 1463 | * and msync() need to guarantee that all the data which was dirty at the time |
| 1464 | * the call was made get new I/O started against them. If wbc->sync_mode is |
| 1465 | * WB_SYNC_ALL then we were called for data integrity and we must wait for |
| 1466 | * existing IO to complete. |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1467 | * |
| 1468 | * To avoid livelocks (when other process dirties new pages), we first tag |
| 1469 | * pages which should be written back with TOWRITE tag and only then start |
| 1470 | * writing them. For data-integrity sync we have to be careful so that we do |
| 1471 | * not miss some pages (e.g., because some other process has cleared TOWRITE |
| 1472 | * tag we set). The rule we follow is that TOWRITE tag can be cleared only |
| 1473 | * by the process clearing the DIRTY tag (and submitting the page for IO). |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1474 | */ |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1475 | int write_cache_pages(struct address_space *mapping, |
| 1476 | struct writeback_control *wbc, writepage_t writepage, |
| 1477 | void *data) |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1478 | { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1479 | int ret = 0; |
| 1480 | int done = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1481 | struct pagevec pvec; |
| 1482 | int nr_pages; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1483 | pgoff_t uninitialized_var(writeback_index); |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1484 | pgoff_t index; |
| 1485 | pgoff_t end; /* Inclusive */ |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1486 | pgoff_t done_index; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1487 | int cycled; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1488 | int range_whole = 0; |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1489 | int tag; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1490 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1491 | pagevec_init(&pvec, 0); |
| 1492 | if (wbc->range_cyclic) { |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1493 | writeback_index = mapping->writeback_index; /* prev offset */ |
| 1494 | index = writeback_index; |
| 1495 | if (index == 0) |
| 1496 | cycled = 1; |
| 1497 | else |
| 1498 | cycled = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1499 | end = -1; |
| 1500 | } else { |
| 1501 | index = wbc->range_start >> PAGE_CACHE_SHIFT; |
| 1502 | end = wbc->range_end >> PAGE_CACHE_SHIFT; |
| 1503 | if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) |
| 1504 | range_whole = 1; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1505 | cycled = 1; /* ignore range_cyclic tests */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1506 | } |
Wu Fengguang | 6e6938b | 2010-06-06 10:38:15 -0600 | [diff] [blame] | 1507 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1508 | tag = PAGECACHE_TAG_TOWRITE; |
| 1509 | else |
| 1510 | tag = PAGECACHE_TAG_DIRTY; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1511 | retry: |
Wu Fengguang | 6e6938b | 2010-06-06 10:38:15 -0600 | [diff] [blame] | 1512 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1513 | tag_pages_for_writeback(mapping, index, end); |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1514 | done_index = index; |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1515 | while (!done && (index <= end)) { |
| 1516 | int i; |
| 1517 | |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1518 | nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag, |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1519 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1); |
| 1520 | if (nr_pages == 0) |
| 1521 | break; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1522 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1523 | for (i = 0; i < nr_pages; i++) { |
| 1524 | struct page *page = pvec.pages[i]; |
| 1525 | |
Nick Piggin | d5482cd | 2009-01-06 14:39:11 -0800 | [diff] [blame] | 1526 | /* |
| 1527 | * At this point, the page may be truncated or |
| 1528 | * invalidated (changing page->mapping to NULL), or |
| 1529 | * even swizzled back from swapper_space to tmpfs file |
| 1530 | * mapping. However, page->index will not change |
| 1531 | * because we have a reference on the page. |
| 1532 | */ |
| 1533 | if (page->index > end) { |
| 1534 | /* |
| 1535 | * can't be range_cyclic (1st pass) because |
| 1536 | * end == -1 in that case. |
| 1537 | */ |
| 1538 | done = 1; |
| 1539 | break; |
| 1540 | } |
| 1541 | |
Jun'ichi Nomura | cf15b07 | 2011-03-22 16:33:40 -0700 | [diff] [blame] | 1542 | done_index = page->index; |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1543 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1544 | lock_page(page); |
| 1545 | |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1546 | /* |
| 1547 | * Page truncated or invalidated. We can freely skip it |
| 1548 | * then, even for data integrity operations: the page |
| 1549 | * has disappeared concurrently, so there could be no |
| 1550 | * real expectation of this data interity operation |
| 1551 | * even if there is now a new, dirty page at the same |
| 1552 | * pagecache address. |
| 1553 | */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1554 | if (unlikely(page->mapping != mapping)) { |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1555 | continue_unlock: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1556 | unlock_page(page); |
| 1557 | continue; |
| 1558 | } |
| 1559 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 1560 | if (!PageDirty(page)) { |
| 1561 | /* someone wrote it for us */ |
| 1562 | goto continue_unlock; |
| 1563 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1564 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 1565 | if (PageWriteback(page)) { |
| 1566 | if (wbc->sync_mode != WB_SYNC_NONE) |
| 1567 | wait_on_page_writeback(page); |
| 1568 | else |
| 1569 | goto continue_unlock; |
| 1570 | } |
| 1571 | |
| 1572 | BUG_ON(PageWriteback(page)); |
| 1573 | if (!clear_page_dirty_for_io(page)) |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1574 | goto continue_unlock; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1575 | |
Dave Chinner | 9e09438 | 2010-07-07 13:24:08 +1000 | [diff] [blame] | 1576 | trace_wbc_writepage(wbc, mapping->backing_dev_info); |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1577 | ret = (*writepage)(page, wbc, data); |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1578 | if (unlikely(ret)) { |
| 1579 | if (ret == AOP_WRITEPAGE_ACTIVATE) { |
| 1580 | unlock_page(page); |
| 1581 | ret = 0; |
| 1582 | } else { |
| 1583 | /* |
| 1584 | * done_index is set past this page, |
| 1585 | * so media errors will not choke |
| 1586 | * background writeout for the entire |
| 1587 | * file. This has consequences for |
| 1588 | * range_cyclic semantics (ie. it may |
| 1589 | * not be suitable for data integrity |
| 1590 | * writeout). |
| 1591 | */ |
Jun'ichi Nomura | cf15b07 | 2011-03-22 16:33:40 -0700 | [diff] [blame] | 1592 | done_index = page->index + 1; |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1593 | done = 1; |
| 1594 | break; |
| 1595 | } |
Dave Chinner | 0b56492 | 2010-06-09 10:37:18 +1000 | [diff] [blame] | 1596 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1597 | |
Dave Chinner | 546a192 | 2010-08-24 11:44:34 +1000 | [diff] [blame] | 1598 | /* |
| 1599 | * We stop writing back only if we are not doing |
| 1600 | * integrity sync. In case of integrity sync we have to |
| 1601 | * keep going until we have written all the pages |
| 1602 | * we tagged for writeback prior to entering this loop. |
| 1603 | */ |
| 1604 | if (--wbc->nr_to_write <= 0 && |
| 1605 | wbc->sync_mode == WB_SYNC_NONE) { |
| 1606 | done = 1; |
| 1607 | break; |
Nick Piggin | 05fe478 | 2009-01-06 14:39:08 -0800 | [diff] [blame] | 1608 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1609 | } |
| 1610 | pagevec_release(&pvec); |
| 1611 | cond_resched(); |
| 1612 | } |
Nick Piggin | 3a4c680 | 2009-02-12 04:34:23 +0100 | [diff] [blame] | 1613 | if (!cycled && !done) { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1614 | /* |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1615 | * range_cyclic: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1616 | * We hit the last page and there is more work to be done: wrap |
| 1617 | * back to the start of the file |
| 1618 | */ |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1619 | cycled = 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1620 | index = 0; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1621 | end = writeback_index - 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1622 | goto retry; |
| 1623 | } |
Dave Chinner | 0b56492 | 2010-06-09 10:37:18 +1000 | [diff] [blame] | 1624 | if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) |
| 1625 | mapping->writeback_index = done_index; |
Aneesh Kumar K.V | 06d6cf6 | 2008-07-11 19:27:31 -0400 | [diff] [blame] | 1626 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1627 | return ret; |
| 1628 | } |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1629 | EXPORT_SYMBOL(write_cache_pages); |
| 1630 | |
| 1631 | /* |
| 1632 | * Function used by generic_writepages to call the real writepage |
| 1633 | * function and set the mapping flags on error |
| 1634 | */ |
| 1635 | static int __writepage(struct page *page, struct writeback_control *wbc, |
| 1636 | void *data) |
| 1637 | { |
| 1638 | struct address_space *mapping = data; |
| 1639 | int ret = mapping->a_ops->writepage(page, wbc); |
| 1640 | mapping_set_error(mapping, ret); |
| 1641 | return ret; |
| 1642 | } |
| 1643 | |
| 1644 | /** |
| 1645 | * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them. |
| 1646 | * @mapping: address space structure to write |
| 1647 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
| 1648 | * |
| 1649 | * This is a library function, which implements the writepages() |
| 1650 | * address_space_operation. |
| 1651 | */ |
| 1652 | int generic_writepages(struct address_space *mapping, |
| 1653 | struct writeback_control *wbc) |
| 1654 | { |
Shaohua Li | 9b6096a | 2011-03-17 10:47:06 +0100 | [diff] [blame] | 1655 | struct blk_plug plug; |
| 1656 | int ret; |
| 1657 | |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1658 | /* deal with chardevs and other special file */ |
| 1659 | if (!mapping->a_ops->writepage) |
| 1660 | return 0; |
| 1661 | |
Shaohua Li | 9b6096a | 2011-03-17 10:47:06 +0100 | [diff] [blame] | 1662 | blk_start_plug(&plug); |
| 1663 | ret = write_cache_pages(mapping, wbc, __writepage, mapping); |
| 1664 | blk_finish_plug(&plug); |
| 1665 | return ret; |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1666 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1667 | |
| 1668 | EXPORT_SYMBOL(generic_writepages); |
| 1669 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1670 | int do_writepages(struct address_space *mapping, struct writeback_control *wbc) |
| 1671 | { |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 1672 | int ret; |
| 1673 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1674 | if (wbc->nr_to_write <= 0) |
| 1675 | return 0; |
| 1676 | if (mapping->a_ops->writepages) |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 1677 | ret = mapping->a_ops->writepages(mapping, wbc); |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 1678 | else |
| 1679 | ret = generic_writepages(mapping, wbc); |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 1680 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1681 | } |
| 1682 | |
| 1683 | /** |
| 1684 | * write_one_page - write out a single page and optionally wait on I/O |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 1685 | * @page: the page to write |
| 1686 | * @wait: if true, wait on writeout |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1687 | * |
| 1688 | * The page must be locked by the caller and will be unlocked upon return. |
| 1689 | * |
| 1690 | * write_one_page() returns a negative error code if I/O failed. |
| 1691 | */ |
| 1692 | int write_one_page(struct page *page, int wait) |
| 1693 | { |
| 1694 | struct address_space *mapping = page->mapping; |
| 1695 | int ret = 0; |
| 1696 | struct writeback_control wbc = { |
| 1697 | .sync_mode = WB_SYNC_ALL, |
| 1698 | .nr_to_write = 1, |
| 1699 | }; |
| 1700 | |
| 1701 | BUG_ON(!PageLocked(page)); |
| 1702 | |
| 1703 | if (wait) |
| 1704 | wait_on_page_writeback(page); |
| 1705 | |
| 1706 | if (clear_page_dirty_for_io(page)) { |
| 1707 | page_cache_get(page); |
| 1708 | ret = mapping->a_ops->writepage(page, &wbc); |
| 1709 | if (ret == 0 && wait) { |
| 1710 | wait_on_page_writeback(page); |
| 1711 | if (PageError(page)) |
| 1712 | ret = -EIO; |
| 1713 | } |
| 1714 | page_cache_release(page); |
| 1715 | } else { |
| 1716 | unlock_page(page); |
| 1717 | } |
| 1718 | return ret; |
| 1719 | } |
| 1720 | EXPORT_SYMBOL(write_one_page); |
| 1721 | |
| 1722 | /* |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 1723 | * For address_spaces which do not use buffers nor write back. |
| 1724 | */ |
| 1725 | int __set_page_dirty_no_writeback(struct page *page) |
| 1726 | { |
| 1727 | if (!PageDirty(page)) |
Bob Liu | c3f0da6 | 2011-01-13 15:45:49 -0800 | [diff] [blame] | 1728 | return !TestSetPageDirty(page); |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 1729 | return 0; |
| 1730 | } |
| 1731 | |
| 1732 | /* |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 1733 | * Helper function for set_page_dirty family. |
| 1734 | * NOTE: This relies on being atomic wrt interrupts. |
| 1735 | */ |
| 1736 | void account_page_dirtied(struct page *page, struct address_space *mapping) |
| 1737 | { |
| 1738 | if (mapping_cap_account_dirty(mapping)) { |
| 1739 | __inc_zone_page_state(page, NR_FILE_DIRTY); |
Michael Rubin | ea941f0 | 2010-10-26 14:21:35 -0700 | [diff] [blame] | 1740 | __inc_zone_page_state(page, NR_DIRTIED); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 1741 | __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); |
Wu Fengguang | c8e28ce | 2011-01-23 10:07:47 -0600 | [diff] [blame] | 1742 | __inc_bdi_stat(mapping->backing_dev_info, BDI_DIRTIED); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 1743 | task_io_account_write(PAGE_CACHE_SIZE); |
| 1744 | } |
| 1745 | } |
Michael Rubin | 679ceac | 2010-08-20 02:31:26 -0700 | [diff] [blame] | 1746 | EXPORT_SYMBOL(account_page_dirtied); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 1747 | |
| 1748 | /* |
Michael Rubin | f629d1c | 2010-10-26 14:21:33 -0700 | [diff] [blame] | 1749 | * Helper function for set_page_writeback family. |
| 1750 | * NOTE: Unlike account_page_dirtied this does not rely on being atomic |
| 1751 | * wrt interrupts. |
| 1752 | */ |
| 1753 | void account_page_writeback(struct page *page) |
| 1754 | { |
| 1755 | inc_zone_page_state(page, NR_WRITEBACK); |
| 1756 | } |
| 1757 | EXPORT_SYMBOL(account_page_writeback); |
| 1758 | |
| 1759 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1760 | * For address_spaces which do not use buffers. Just tag the page as dirty in |
| 1761 | * its radix tree. |
| 1762 | * |
| 1763 | * This is also used when a single buffer is being dirtied: we want to set the |
| 1764 | * page dirty in that case, but not all the buffers. This is a "bottom-up" |
| 1765 | * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying. |
| 1766 | * |
| 1767 | * Most callers have locked the page, which pins the address_space in memory. |
| 1768 | * But zap_pte_range() does not lock the page, however in that case the |
| 1769 | * mapping is pinned by the vma's ->vm_file reference. |
| 1770 | * |
| 1771 | * We take care to handle the case where the page was truncated from the |
Simon Arlott | 183ff22 | 2007-10-20 01:27:18 +0200 | [diff] [blame] | 1772 | * mapping by re-checking page_mapping() inside tree_lock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1773 | */ |
| 1774 | int __set_page_dirty_nobuffers(struct page *page) |
| 1775 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1776 | if (!TestSetPageDirty(page)) { |
| 1777 | struct address_space *mapping = page_mapping(page); |
| 1778 | struct address_space *mapping2; |
| 1779 | |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1780 | if (!mapping) |
| 1781 | return 1; |
| 1782 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1783 | spin_lock_irq(&mapping->tree_lock); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1784 | mapping2 = page_mapping(page); |
| 1785 | if (mapping2) { /* Race with truncate? */ |
| 1786 | BUG_ON(mapping2 != mapping); |
Nick Piggin | 787d221 | 2007-07-17 04:03:34 -0700 | [diff] [blame] | 1787 | WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page)); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 1788 | account_page_dirtied(page, mapping); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1789 | radix_tree_tag_set(&mapping->page_tree, |
| 1790 | page_index(page), PAGECACHE_TAG_DIRTY); |
| 1791 | } |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1792 | spin_unlock_irq(&mapping->tree_lock); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1793 | if (mapping->host) { |
| 1794 | /* !PageAnon && !swapper_space */ |
| 1795 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1796 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 1797 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1798 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 1799 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1800 | } |
| 1801 | EXPORT_SYMBOL(__set_page_dirty_nobuffers); |
| 1802 | |
| 1803 | /* |
| 1804 | * When a writepage implementation decides that it doesn't want to write this |
| 1805 | * page for some reason, it should redirty the locked page via |
| 1806 | * redirty_page_for_writepage() and it should then unlock the page and return 0 |
| 1807 | */ |
| 1808 | int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page) |
| 1809 | { |
| 1810 | wbc->pages_skipped++; |
| 1811 | return __set_page_dirty_nobuffers(page); |
| 1812 | } |
| 1813 | EXPORT_SYMBOL(redirty_page_for_writepage); |
| 1814 | |
| 1815 | /* |
Wu Fengguang | 6746aff | 2009-09-16 11:50:14 +0200 | [diff] [blame] | 1816 | * Dirty a page. |
| 1817 | * |
| 1818 | * For pages with a mapping this should be done under the page lock |
| 1819 | * for the benefit of asynchronous memory errors who prefer a consistent |
| 1820 | * dirty state. This rule can be broken in some special cases, |
| 1821 | * but should be better not to. |
| 1822 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1823 | * If the mapping doesn't provide a set_page_dirty a_op, then |
| 1824 | * just fall through and assume that it wants buffer_heads. |
| 1825 | */ |
Nick Piggin | 1cf6e7d | 2009-02-18 14:48:18 -0800 | [diff] [blame] | 1826 | int set_page_dirty(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1827 | { |
| 1828 | struct address_space *mapping = page_mapping(page); |
| 1829 | |
| 1830 | if (likely(mapping)) { |
| 1831 | int (*spd)(struct page *) = mapping->a_ops->set_page_dirty; |
Minchan Kim | 278df9f | 2011-03-22 16:32:54 -0700 | [diff] [blame] | 1832 | /* |
| 1833 | * readahead/lru_deactivate_page could remain |
| 1834 | * PG_readahead/PG_reclaim due to race with end_page_writeback |
| 1835 | * About readahead, if the page is written, the flags would be |
| 1836 | * reset. So no problem. |
| 1837 | * About lru_deactivate_page, if the page is redirty, the flag |
| 1838 | * will be reset. So no problem. but if the page is used by readahead |
| 1839 | * it will confuse readahead and make it restart the size rampup |
| 1840 | * process. But it's a trivial problem. |
| 1841 | */ |
| 1842 | ClearPageReclaim(page); |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 1843 | #ifdef CONFIG_BLOCK |
| 1844 | if (!spd) |
| 1845 | spd = __set_page_dirty_buffers; |
| 1846 | #endif |
| 1847 | return (*spd)(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1848 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 1849 | if (!PageDirty(page)) { |
| 1850 | if (!TestSetPageDirty(page)) |
| 1851 | return 1; |
| 1852 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1853 | return 0; |
| 1854 | } |
| 1855 | EXPORT_SYMBOL(set_page_dirty); |
| 1856 | |
| 1857 | /* |
| 1858 | * set_page_dirty() is racy if the caller has no reference against |
| 1859 | * page->mapping->host, and if the page is unlocked. This is because another |
| 1860 | * CPU could truncate the page off the mapping and then free the mapping. |
| 1861 | * |
| 1862 | * Usually, the page _is_ locked, or the caller is a user-space process which |
| 1863 | * holds a reference on the inode by having an open file. |
| 1864 | * |
| 1865 | * In other cases, the page should be locked before running set_page_dirty(). |
| 1866 | */ |
| 1867 | int set_page_dirty_lock(struct page *page) |
| 1868 | { |
| 1869 | int ret; |
| 1870 | |
Jens Axboe | 7eaceac | 2011-03-10 08:52:07 +0100 | [diff] [blame] | 1871 | lock_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1872 | ret = set_page_dirty(page); |
| 1873 | unlock_page(page); |
| 1874 | return ret; |
| 1875 | } |
| 1876 | EXPORT_SYMBOL(set_page_dirty_lock); |
| 1877 | |
| 1878 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1879 | * Clear a page's dirty flag, while caring for dirty memory accounting. |
| 1880 | * Returns true if the page was previously dirty. |
| 1881 | * |
| 1882 | * This is for preparing to put the page under writeout. We leave the page |
| 1883 | * tagged as dirty in the radix tree so that a concurrent write-for-sync |
| 1884 | * can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage |
| 1885 | * implementation will run either set_page_writeback() or set_page_dirty(), |
| 1886 | * at which stage we bring the page's dirty flag and radix-tree dirty tag |
| 1887 | * back into sync. |
| 1888 | * |
| 1889 | * This incoherency between the page's dirty flag and radix-tree tag is |
| 1890 | * unfortunate, but it only exists while the page is locked. |
| 1891 | */ |
| 1892 | int clear_page_dirty_for_io(struct page *page) |
| 1893 | { |
| 1894 | struct address_space *mapping = page_mapping(page); |
| 1895 | |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 1896 | BUG_ON(!PageLocked(page)); |
| 1897 | |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1898 | if (mapping && mapping_cap_account_dirty(mapping)) { |
| 1899 | /* |
| 1900 | * Yes, Virginia, this is indeed insane. |
| 1901 | * |
| 1902 | * We use this sequence to make sure that |
| 1903 | * (a) we account for dirty stats properly |
| 1904 | * (b) we tell the low-level filesystem to |
| 1905 | * mark the whole page dirty if it was |
| 1906 | * dirty in a pagetable. Only to then |
| 1907 | * (c) clean the page again and return 1 to |
| 1908 | * cause the writeback. |
| 1909 | * |
| 1910 | * This way we avoid all nasty races with the |
| 1911 | * dirty bit in multiple places and clearing |
| 1912 | * them concurrently from different threads. |
| 1913 | * |
| 1914 | * Note! Normally the "set_page_dirty(page)" |
| 1915 | * has no effect on the actual dirty bit - since |
| 1916 | * that will already usually be set. But we |
| 1917 | * need the side effects, and it can help us |
| 1918 | * avoid races. |
| 1919 | * |
| 1920 | * We basically use the page "master dirty bit" |
| 1921 | * as a serialization point for all the different |
| 1922 | * threads doing their things. |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1923 | */ |
| 1924 | if (page_mkclean(page)) |
| 1925 | set_page_dirty(page); |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 1926 | /* |
| 1927 | * We carefully synchronise fault handlers against |
| 1928 | * installing a dirty pte and marking the page dirty |
| 1929 | * at this point. We do this by having them hold the |
| 1930 | * page lock at some point after installing their |
| 1931 | * pte, but before marking the page dirty. |
| 1932 | * Pages are always locked coming in here, so we get |
| 1933 | * the desired exclusion. See mm/memory.c:do_wp_page() |
| 1934 | * for more comments. |
| 1935 | */ |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1936 | if (TestClearPageDirty(page)) { |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1937 | dec_zone_page_state(page, NR_FILE_DIRTY); |
Peter Zijlstra | c9e51e4 | 2007-10-16 23:25:47 -0700 | [diff] [blame] | 1938 | dec_bdi_stat(mapping->backing_dev_info, |
| 1939 | BDI_RECLAIMABLE); |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1940 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1941 | } |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1942 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1943 | } |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1944 | return TestClearPageDirty(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1945 | } |
Hans Reiser | 58bb01a | 2005-11-18 01:10:53 -0800 | [diff] [blame] | 1946 | EXPORT_SYMBOL(clear_page_dirty_for_io); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1947 | |
| 1948 | int test_clear_page_writeback(struct page *page) |
| 1949 | { |
| 1950 | struct address_space *mapping = page_mapping(page); |
| 1951 | int ret; |
| 1952 | |
| 1953 | if (mapping) { |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1954 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1955 | unsigned long flags; |
| 1956 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1957 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1958 | ret = TestClearPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1959 | if (ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1960 | radix_tree_tag_clear(&mapping->page_tree, |
| 1961 | page_index(page), |
| 1962 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 1963 | if (bdi_cap_account_writeback(bdi)) { |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1964 | __dec_bdi_stat(bdi, BDI_WRITEBACK); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1965 | __bdi_writeout_inc(bdi); |
| 1966 | } |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1967 | } |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1968 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1969 | } else { |
| 1970 | ret = TestClearPageWriteback(page); |
| 1971 | } |
Wu Fengguang | 99b12e3 | 2011-07-25 17:12:37 -0700 | [diff] [blame] | 1972 | if (ret) { |
Andrew Morton | d688abf | 2007-07-19 01:49:17 -0700 | [diff] [blame] | 1973 | dec_zone_page_state(page, NR_WRITEBACK); |
Wu Fengguang | 99b12e3 | 2011-07-25 17:12:37 -0700 | [diff] [blame] | 1974 | inc_zone_page_state(page, NR_WRITTEN); |
| 1975 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1976 | return ret; |
| 1977 | } |
| 1978 | |
| 1979 | int test_set_page_writeback(struct page *page) |
| 1980 | { |
| 1981 | struct address_space *mapping = page_mapping(page); |
| 1982 | int ret; |
| 1983 | |
| 1984 | if (mapping) { |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1985 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1986 | unsigned long flags; |
| 1987 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1988 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1989 | ret = TestSetPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1990 | if (!ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1991 | radix_tree_tag_set(&mapping->page_tree, |
| 1992 | page_index(page), |
| 1993 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 1994 | if (bdi_cap_account_writeback(bdi)) |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1995 | __inc_bdi_stat(bdi, BDI_WRITEBACK); |
| 1996 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1997 | if (!PageDirty(page)) |
| 1998 | radix_tree_tag_clear(&mapping->page_tree, |
| 1999 | page_index(page), |
| 2000 | PAGECACHE_TAG_DIRTY); |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2001 | radix_tree_tag_clear(&mapping->page_tree, |
| 2002 | page_index(page), |
| 2003 | PAGECACHE_TAG_TOWRITE); |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2004 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2005 | } else { |
| 2006 | ret = TestSetPageWriteback(page); |
| 2007 | } |
Andrew Morton | d688abf | 2007-07-19 01:49:17 -0700 | [diff] [blame] | 2008 | if (!ret) |
Michael Rubin | f629d1c | 2010-10-26 14:21:33 -0700 | [diff] [blame] | 2009 | account_page_writeback(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2010 | return ret; |
| 2011 | |
| 2012 | } |
| 2013 | EXPORT_SYMBOL(test_set_page_writeback); |
| 2014 | |
| 2015 | /* |
Nick Piggin | 0012818 | 2007-10-16 01:24:40 -0700 | [diff] [blame] | 2016 | * Return true if any of the pages in the mapping are marked with the |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2017 | * passed tag. |
| 2018 | */ |
| 2019 | int mapping_tagged(struct address_space *mapping, int tag) |
| 2020 | { |
Konstantin Khlebnikov | 72c4783 | 2011-07-25 17:12:31 -0700 | [diff] [blame] | 2021 | return radix_tree_tagged(&mapping->page_tree, tag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2022 | } |
| 2023 | EXPORT_SYMBOL(mapping_tagged); |