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 | ff01bb4 | 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> |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 37 | #include <linux/timer.h> |
Clark Williams | 8bd75c7 | 2013-02-07 09:47:07 -0600 | [diff] [blame] | 38 | #include <linux/sched/rt.h> |
Lisa Du | 6e543d5 | 2013-09-11 14:22:36 -0700 | [diff] [blame] | 39 | #include <linux/mm_inline.h> |
Dave Chinner | 028c2dd | 2010-07-07 13:24:07 +1000 | [diff] [blame] | 40 | #include <trace/events/writeback.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | |
Lisa Du | 6e543d5 | 2013-09-11 14:22:36 -0700 | [diff] [blame] | 42 | #include "internal.h" |
| 43 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | /* |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 45 | * Sleep at most 200ms at a time in balance_dirty_pages(). |
| 46 | */ |
| 47 | #define MAX_PAUSE max(HZ/5, 1) |
| 48 | |
| 49 | /* |
Wu Fengguang | 5b9b357 | 2011-12-06 13:17:17 -0600 | [diff] [blame] | 50 | * Try to keep balance_dirty_pages() call intervals higher than this many pages |
| 51 | * by raising pause time to max_pause when falls below it. |
| 52 | */ |
| 53 | #define DIRTY_POLL_THRESH (128 >> (PAGE_SHIFT - 10)) |
| 54 | |
| 55 | /* |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 56 | * Estimate write bandwidth at 200ms intervals. |
| 57 | */ |
| 58 | #define BANDWIDTH_INTERVAL max(HZ/5, 1) |
| 59 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 60 | #define RATELIMIT_CALC_SHIFT 10 |
| 61 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 62 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited |
| 64 | * will look to see if it needs to force writeback or throttling. |
| 65 | */ |
| 66 | static long ratelimit_pages = 32; |
| 67 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | /* The following parameters are exported via /proc/sys/vm */ |
| 69 | |
| 70 | /* |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 71 | * Start background writeback (via writeback threads) at this percentage |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 72 | */ |
Wu Fengguang | 1b5e62b | 2009-03-23 08:57:38 +0800 | [diff] [blame] | 73 | int dirty_background_ratio = 10; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | |
| 75 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 76 | * dirty_background_bytes starts at 0 (disabled) so that it is a function of |
| 77 | * dirty_background_ratio * the amount of dirtyable memory |
| 78 | */ |
| 79 | unsigned long dirty_background_bytes; |
| 80 | |
| 81 | /* |
Bron Gondwana | 195cf453 | 2008-02-04 22:29:20 -0800 | [diff] [blame] | 82 | * free highmem will not be subtracted from the total free memory |
| 83 | * for calculating free ratios if vm_highmem_is_dirtyable is true |
| 84 | */ |
| 85 | int vm_highmem_is_dirtyable; |
| 86 | |
| 87 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | * The generator of dirty data starts writeback at this percentage |
| 89 | */ |
Wu Fengguang | 1b5e62b | 2009-03-23 08:57:38 +0800 | [diff] [blame] | 90 | int vm_dirty_ratio = 20; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 91 | |
| 92 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 93 | * vm_dirty_bytes starts at 0 (disabled) so that it is a function of |
| 94 | * vm_dirty_ratio * the amount of dirtyable memory |
| 95 | */ |
| 96 | unsigned long vm_dirty_bytes; |
| 97 | |
| 98 | /* |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 99 | * The interval between `kupdate'-style writebacks |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 100 | */ |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 101 | unsigned int dirty_writeback_interval = 5 * 100; /* centiseconds */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 102 | |
Artem Bityutskiy | 91913a2 | 2012-03-21 22:33:00 -0400 | [diff] [blame] | 103 | EXPORT_SYMBOL_GPL(dirty_writeback_interval); |
| 104 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | /* |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 106 | * The longest time for which data is allowed to remain dirty |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 107 | */ |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 108 | unsigned int dirty_expire_interval = 30 * 100; /* centiseconds */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 109 | |
| 110 | /* |
| 111 | * Flag that makes the machine dump writes/reads and block dirtyings. |
| 112 | */ |
| 113 | int block_dump; |
| 114 | |
| 115 | /* |
Bart Samwel | ed5b43f | 2006-03-24 03:15:49 -0800 | [diff] [blame] | 116 | * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies: |
| 117 | * 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] | 118 | */ |
| 119 | int laptop_mode; |
| 120 | |
| 121 | EXPORT_SYMBOL(laptop_mode); |
| 122 | |
| 123 | /* End of sysctl-exported parameters */ |
| 124 | |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 125 | unsigned long global_dirty_limit; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 126 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 127 | /* |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 128 | * Scale the writeback cache size proportional to the relative writeout speeds. |
| 129 | * |
| 130 | * We do this by keeping a floating proportion between BDIs, based on page |
| 131 | * writeback completions [end_page_writeback()]. Those devices that write out |
| 132 | * pages fastest will get the larger share, while the slower will get a smaller |
| 133 | * share. |
| 134 | * |
| 135 | * We use page writeout completions because we are interested in getting rid of |
| 136 | * dirty pages. Having them written out is the primary goal. |
| 137 | * |
| 138 | * We introduce a concept of time, a period over which we measure these events, |
| 139 | * because demand can/will vary over time. The length of this period itself is |
| 140 | * measured in page writeback completions. |
| 141 | * |
| 142 | */ |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 143 | static struct fprop_global writeout_completions; |
| 144 | |
| 145 | static void writeout_period(unsigned long t); |
| 146 | /* Timer for aging of writeout_completions */ |
| 147 | static struct timer_list writeout_period_timer = |
| 148 | TIMER_DEFERRED_INITIALIZER(writeout_period, 0, 0); |
| 149 | static unsigned long writeout_period_time = 0; |
| 150 | |
| 151 | /* |
| 152 | * Length of period for aging writeout fractions of bdis. This is an |
| 153 | * arbitrarily chosen number. The longer the period, the slower fractions will |
| 154 | * reflect changes in current writeout rate. |
| 155 | */ |
| 156 | #define VM_COMPLETIONS_PERIOD_LEN (3*HZ) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 157 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 158 | /* |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 159 | * In a memory zone, there is a certain amount of pages we consider |
| 160 | * available for the page cache, which is essentially the number of |
| 161 | * free and reclaimable pages, minus some zone reserves to protect |
| 162 | * lowmem and the ability to uphold the zone's watermarks without |
| 163 | * requiring writeback. |
| 164 | * |
| 165 | * This number of dirtyable pages is the base value of which the |
| 166 | * user-configurable dirty ratio is the effictive number of pages that |
| 167 | * are allowed to be actually dirtied. Per individual zone, or |
| 168 | * globally by using the sum of dirtyable pages over all zones. |
| 169 | * |
| 170 | * Because the user is allowed to specify the dirty limit globally as |
| 171 | * absolute number of bytes, calculating the per-zone dirty limit can |
| 172 | * require translating the configured limit into a percentage of |
| 173 | * global dirtyable memory first. |
| 174 | */ |
| 175 | |
Johannes Weiner | a804552b | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 176 | /** |
| 177 | * zone_dirtyable_memory - number of dirtyable pages in a zone |
| 178 | * @zone: the zone |
| 179 | * |
| 180 | * Returns the zone's number of pages potentially available for dirty |
| 181 | * page cache. This is the base value for the per-zone dirty limits. |
| 182 | */ |
| 183 | static unsigned long zone_dirtyable_memory(struct zone *zone) |
| 184 | { |
| 185 | unsigned long nr_pages; |
| 186 | |
| 187 | nr_pages = zone_page_state(zone, NR_FREE_PAGES); |
| 188 | nr_pages -= min(nr_pages, zone->dirty_balance_reserve); |
| 189 | |
Johannes Weiner | a1c3bfb | 2014-01-29 14:05:41 -0800 | [diff] [blame] | 190 | nr_pages += zone_page_state(zone, NR_INACTIVE_FILE); |
| 191 | nr_pages += zone_page_state(zone, NR_ACTIVE_FILE); |
Johannes Weiner | a804552b | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 192 | |
| 193 | return nr_pages; |
| 194 | } |
| 195 | |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 196 | static unsigned long highmem_dirtyable_memory(unsigned long total) |
| 197 | { |
| 198 | #ifdef CONFIG_HIGHMEM |
| 199 | int node; |
| 200 | unsigned long x = 0; |
| 201 | |
| 202 | for_each_node_state(node, N_HIGH_MEMORY) { |
Johannes Weiner | a804552b | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 203 | struct zone *z = &NODE_DATA(node)->node_zones[ZONE_HIGHMEM]; |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 204 | |
Johannes Weiner | a804552b | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 205 | x += zone_dirtyable_memory(z); |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 206 | } |
| 207 | /* |
Sonny Rao | c8b74c2f | 2012-12-20 15:05:07 -0800 | [diff] [blame] | 208 | * Unreclaimable memory (kernel memory or anonymous memory |
| 209 | * without swap) can bring down the dirtyable pages below |
| 210 | * the zone's dirty balance reserve and the above calculation |
| 211 | * will underflow. However we still want to add in nodes |
| 212 | * which are below threshold (negative values) to get a more |
| 213 | * accurate calculation but make sure that the total never |
| 214 | * underflows. |
| 215 | */ |
| 216 | if ((long)x < 0) |
| 217 | x = 0; |
| 218 | |
| 219 | /* |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 220 | * Make sure that the number of highmem pages is never larger |
| 221 | * than the number of the total dirtyable memory. This can only |
| 222 | * occur in very strange VM situations but we want to make sure |
| 223 | * that this does not occur. |
| 224 | */ |
| 225 | return min(x, total); |
| 226 | #else |
| 227 | return 0; |
| 228 | #endif |
| 229 | } |
| 230 | |
| 231 | /** |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 232 | * global_dirtyable_memory - number of globally dirtyable pages |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 233 | * |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 234 | * Returns the global number of pages potentially available for dirty |
| 235 | * page cache. This is the base value for the global dirty limits. |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 236 | */ |
H Hartley Sweeten | 18cf8cf | 2012-04-12 13:44:20 -0700 | [diff] [blame] | 237 | static unsigned long global_dirtyable_memory(void) |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 238 | { |
| 239 | unsigned long x; |
| 240 | |
Johannes Weiner | a804552b | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 241 | x = global_page_state(NR_FREE_PAGES); |
Sonny Rao | c8b74c2f | 2012-12-20 15:05:07 -0800 | [diff] [blame] | 242 | x -= min(x, dirty_balance_reserve); |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 243 | |
Johannes Weiner | a1c3bfb | 2014-01-29 14:05:41 -0800 | [diff] [blame] | 244 | x += global_page_state(NR_INACTIVE_FILE); |
| 245 | x += global_page_state(NR_ACTIVE_FILE); |
Johannes Weiner | a804552b | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 246 | |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 247 | if (!vm_highmem_is_dirtyable) |
| 248 | x -= highmem_dirtyable_memory(x); |
| 249 | |
| 250 | return x + 1; /* Ensure that we never return 0 */ |
| 251 | } |
| 252 | |
| 253 | /* |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 254 | * global_dirty_limits - background-writeback and dirty-throttling thresholds |
| 255 | * |
| 256 | * Calculate the dirty thresholds based on sysctl parameters |
| 257 | * - vm.dirty_background_ratio or vm.dirty_background_bytes |
| 258 | * - vm.dirty_ratio or vm.dirty_bytes |
| 259 | * The dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and |
| 260 | * real-time tasks. |
| 261 | */ |
| 262 | void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty) |
| 263 | { |
David Rientjes | 9ef0a0f | 2014-08-06 16:07:31 -0700 | [diff] [blame] | 264 | const unsigned long available_memory = global_dirtyable_memory(); |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 265 | unsigned long background; |
| 266 | unsigned long dirty; |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 267 | struct task_struct *tsk; |
| 268 | |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 269 | if (vm_dirty_bytes) |
| 270 | dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE); |
| 271 | else |
| 272 | dirty = (vm_dirty_ratio * available_memory) / 100; |
| 273 | |
| 274 | if (dirty_background_bytes) |
| 275 | background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE); |
| 276 | else |
| 277 | background = (dirty_background_ratio * available_memory) / 100; |
| 278 | |
| 279 | if (background >= dirty) |
| 280 | background = dirty / 2; |
| 281 | tsk = current; |
| 282 | if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) { |
| 283 | background += background / 4; |
| 284 | dirty += dirty / 4; |
| 285 | } |
| 286 | *pbackground = background; |
| 287 | *pdirty = dirty; |
| 288 | trace_global_dirty_state(background, dirty); |
| 289 | } |
| 290 | |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 291 | /** |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 292 | * zone_dirty_limit - maximum number of dirty pages allowed in a zone |
| 293 | * @zone: the zone |
| 294 | * |
| 295 | * Returns the maximum number of dirty pages allowed in a zone, based |
| 296 | * on the zone's dirtyable memory. |
| 297 | */ |
| 298 | static unsigned long zone_dirty_limit(struct zone *zone) |
| 299 | { |
| 300 | unsigned long zone_memory = zone_dirtyable_memory(zone); |
| 301 | struct task_struct *tsk = current; |
| 302 | unsigned long dirty; |
| 303 | |
| 304 | if (vm_dirty_bytes) |
| 305 | dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE) * |
| 306 | zone_memory / global_dirtyable_memory(); |
| 307 | else |
| 308 | dirty = vm_dirty_ratio * zone_memory / 100; |
| 309 | |
| 310 | if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) |
| 311 | dirty += dirty / 4; |
| 312 | |
| 313 | return dirty; |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * zone_dirty_ok - tells whether a zone is within its dirty limits |
| 318 | * @zone: the zone to check |
| 319 | * |
| 320 | * Returns %true when the dirty pages in @zone are within the zone's |
| 321 | * dirty limit, %false if the limit is exceeded. |
| 322 | */ |
| 323 | bool zone_dirty_ok(struct zone *zone) |
| 324 | { |
| 325 | unsigned long limit = zone_dirty_limit(zone); |
| 326 | |
| 327 | return zone_page_state(zone, NR_FILE_DIRTY) + |
| 328 | zone_page_state(zone, NR_UNSTABLE_NFS) + |
| 329 | zone_page_state(zone, NR_WRITEBACK) <= limit; |
| 330 | } |
| 331 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 332 | int dirty_background_ratio_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 333 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 334 | loff_t *ppos) |
| 335 | { |
| 336 | int ret; |
| 337 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 338 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 339 | if (ret == 0 && write) |
| 340 | dirty_background_bytes = 0; |
| 341 | return ret; |
| 342 | } |
| 343 | |
| 344 | int dirty_background_bytes_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 345 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 346 | loff_t *ppos) |
| 347 | { |
| 348 | int ret; |
| 349 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 350 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 351 | if (ret == 0 && write) |
| 352 | dirty_background_ratio = 0; |
| 353 | return ret; |
| 354 | } |
| 355 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 356 | int dirty_ratio_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 357 | void __user *buffer, size_t *lenp, |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 358 | loff_t *ppos) |
| 359 | { |
| 360 | int old_ratio = vm_dirty_ratio; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 361 | int ret; |
| 362 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 363 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 364 | if (ret == 0 && write && vm_dirty_ratio != old_ratio) { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 365 | writeback_set_ratelimit(); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 366 | vm_dirty_bytes = 0; |
| 367 | } |
| 368 | return ret; |
| 369 | } |
| 370 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 371 | int dirty_bytes_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 372 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 373 | loff_t *ppos) |
| 374 | { |
Sven Wegener | fc3501d | 2009-02-11 13:04:23 -0800 | [diff] [blame] | 375 | unsigned long old_bytes = vm_dirty_bytes; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 376 | int ret; |
| 377 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 378 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 379 | if (ret == 0 && write && vm_dirty_bytes != old_bytes) { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 380 | writeback_set_ratelimit(); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 381 | vm_dirty_ratio = 0; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 382 | } |
| 383 | return ret; |
| 384 | } |
| 385 | |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 386 | static unsigned long wp_next_time(unsigned long cur_time) |
| 387 | { |
| 388 | cur_time += VM_COMPLETIONS_PERIOD_LEN; |
| 389 | /* 0 has a special meaning... */ |
| 390 | if (!cur_time) |
| 391 | return 1; |
| 392 | return cur_time; |
| 393 | } |
| 394 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 395 | /* |
| 396 | * Increment the BDI's writeout completion count and the global writeout |
| 397 | * completion count. Called from test_clear_page_writeback(). |
| 398 | */ |
| 399 | static inline void __bdi_writeout_inc(struct backing_dev_info *bdi) |
| 400 | { |
Jan Kara | f7d2b1e | 2010-12-08 22:44:24 -0600 | [diff] [blame] | 401 | __inc_bdi_stat(bdi, BDI_WRITTEN); |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 402 | __fprop_inc_percpu_max(&writeout_completions, &bdi->completions, |
| 403 | bdi->max_prop_frac); |
| 404 | /* First event after period switching was turned off? */ |
| 405 | if (!unlikely(writeout_period_time)) { |
| 406 | /* |
| 407 | * We can race with other __bdi_writeout_inc calls here but |
| 408 | * it does not cause any harm since the resulting time when |
| 409 | * timer will fire and what is in writeout_period_time will be |
| 410 | * roughly the same. |
| 411 | */ |
| 412 | writeout_period_time = wp_next_time(jiffies); |
| 413 | mod_timer(&writeout_period_timer, writeout_period_time); |
| 414 | } |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 415 | } |
| 416 | |
Miklos Szeredi | dd5656e | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 417 | void bdi_writeout_inc(struct backing_dev_info *bdi) |
| 418 | { |
| 419 | unsigned long flags; |
| 420 | |
| 421 | local_irq_save(flags); |
| 422 | __bdi_writeout_inc(bdi); |
| 423 | local_irq_restore(flags); |
| 424 | } |
| 425 | EXPORT_SYMBOL_GPL(bdi_writeout_inc); |
| 426 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 427 | /* |
| 428 | * Obtain an accurate fraction of the BDI's portion. |
| 429 | */ |
| 430 | static void bdi_writeout_fraction(struct backing_dev_info *bdi, |
| 431 | long *numerator, long *denominator) |
| 432 | { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 433 | fprop_fraction_percpu(&writeout_completions, &bdi->completions, |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 434 | numerator, denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 435 | } |
| 436 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 437 | /* |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 438 | * On idle system, we can be called long after we scheduled because we use |
| 439 | * deferred timers so count with missed periods. |
| 440 | */ |
| 441 | static void writeout_period(unsigned long t) |
| 442 | { |
| 443 | int miss_periods = (jiffies - writeout_period_time) / |
| 444 | VM_COMPLETIONS_PERIOD_LEN; |
| 445 | |
| 446 | if (fprop_new_period(&writeout_completions, miss_periods + 1)) { |
| 447 | writeout_period_time = wp_next_time(writeout_period_time + |
| 448 | miss_periods * VM_COMPLETIONS_PERIOD_LEN); |
| 449 | mod_timer(&writeout_period_timer, writeout_period_time); |
| 450 | } else { |
| 451 | /* |
| 452 | * Aging has zeroed all fractions. Stop wasting CPU on period |
| 453 | * updates. |
| 454 | */ |
| 455 | writeout_period_time = 0; |
| 456 | } |
| 457 | } |
| 458 | |
| 459 | /* |
Johannes Weiner | d08c429 | 2011-10-31 17:07:05 -0700 | [diff] [blame] | 460 | * bdi_min_ratio keeps the sum of the minimum dirty shares of all |
| 461 | * registered backing devices, which, for obvious reasons, can not |
| 462 | * exceed 100%. |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 463 | */ |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 464 | static unsigned int bdi_min_ratio; |
| 465 | |
| 466 | int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) |
| 467 | { |
| 468 | int ret = 0; |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 469 | |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 470 | spin_lock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 471 | if (min_ratio > bdi->max_ratio) { |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 472 | ret = -EINVAL; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 473 | } else { |
| 474 | min_ratio -= bdi->min_ratio; |
| 475 | if (bdi_min_ratio + min_ratio < 100) { |
| 476 | bdi_min_ratio += min_ratio; |
| 477 | bdi->min_ratio += min_ratio; |
| 478 | } else { |
| 479 | ret = -EINVAL; |
| 480 | } |
| 481 | } |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 482 | spin_unlock_bh(&bdi_lock); |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 483 | |
| 484 | return ret; |
| 485 | } |
| 486 | |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 487 | int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) |
| 488 | { |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 489 | int ret = 0; |
| 490 | |
| 491 | if (max_ratio > 100) |
| 492 | return -EINVAL; |
| 493 | |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 494 | spin_lock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 495 | if (bdi->min_ratio > max_ratio) { |
| 496 | ret = -EINVAL; |
| 497 | } else { |
| 498 | bdi->max_ratio = max_ratio; |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 499 | bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 500 | } |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 501 | spin_unlock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 502 | |
| 503 | return ret; |
| 504 | } |
| 505 | EXPORT_SYMBOL(bdi_set_max_ratio); |
| 506 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 507 | static unsigned long dirty_freerun_ceiling(unsigned long thresh, |
| 508 | unsigned long bg_thresh) |
| 509 | { |
| 510 | return (thresh + bg_thresh) / 2; |
| 511 | } |
| 512 | |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 513 | static unsigned long hard_dirty_limit(unsigned long thresh) |
| 514 | { |
| 515 | return max(thresh, global_dirty_limit); |
| 516 | } |
| 517 | |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 518 | /** |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 519 | * bdi_dirty_limit - @bdi's share of dirty throttling threshold |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 520 | * @bdi: the backing_dev_info to query |
| 521 | * @dirty: global dirty limit in pages |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 522 | * |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 523 | * Returns @bdi's dirty limit in pages. The term "dirty" in the context of |
| 524 | * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages. |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 525 | * |
| 526 | * Note that balance_dirty_pages() will only seriously take it as a hard limit |
| 527 | * when sleeping max_pause per page is not enough to keep the dirty pages under |
| 528 | * control. For example, when the device is completely stalled due to some error |
| 529 | * conditions, or when there are 1000 dd tasks writing to a slow 10MB/s USB key. |
| 530 | * In the other normal situations, it acts more gently by throttling the tasks |
| 531 | * 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] | 532 | * |
| 533 | * 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] | 534 | * - starving fast devices |
| 535 | * - piling up dirty pages (that will take long time to sync) on slow devices |
| 536 | * |
| 537 | * The bdi's share of dirty limit will be adapting to its throughput and |
| 538 | * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set. |
| 539 | */ |
| 540 | 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] | 541 | { |
| 542 | u64 bdi_dirty; |
| 543 | long numerator, denominator; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 544 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 545 | /* |
| 546 | * Calculate this BDI's share of the dirty ratio. |
| 547 | */ |
| 548 | bdi_writeout_fraction(bdi, &numerator, &denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 549 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 550 | bdi_dirty = (dirty * (100 - bdi_min_ratio)) / 100; |
| 551 | bdi_dirty *= numerator; |
| 552 | do_div(bdi_dirty, denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 553 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 554 | bdi_dirty += (dirty * bdi->min_ratio) / 100; |
| 555 | if (bdi_dirty > (dirty * bdi->max_ratio) / 100) |
| 556 | bdi_dirty = dirty * bdi->max_ratio / 100; |
| 557 | |
| 558 | return bdi_dirty; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 559 | } |
| 560 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 561 | /* |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 562 | * setpoint - dirty 3 |
| 563 | * f(dirty) := 1.0 + (----------------) |
| 564 | * limit - setpoint |
| 565 | * |
| 566 | * it's a 3rd order polynomial that subjects to |
| 567 | * |
| 568 | * (1) f(freerun) = 2.0 => rampup dirty_ratelimit reasonably fast |
| 569 | * (2) f(setpoint) = 1.0 => the balance point |
| 570 | * (3) f(limit) = 0 => the hard limit |
| 571 | * (4) df/dx <= 0 => negative feedback control |
| 572 | * (5) the closer to setpoint, the smaller |df/dx| (and the reverse) |
| 573 | * => fast response on large errors; small oscillation near setpoint |
| 574 | */ |
Rik van Riel | d5c9fde | 2014-05-06 12:50:01 -0700 | [diff] [blame] | 575 | static long long pos_ratio_polynom(unsigned long setpoint, |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 576 | unsigned long dirty, |
| 577 | unsigned long limit) |
| 578 | { |
| 579 | long long pos_ratio; |
| 580 | long x; |
| 581 | |
Rik van Riel | d5c9fde | 2014-05-06 12:50:01 -0700 | [diff] [blame] | 582 | x = div64_s64(((s64)setpoint - (s64)dirty) << RATELIMIT_CALC_SHIFT, |
Tejun Heo | 464d138 | 2015-04-21 16:49:13 -0400 | [diff] [blame] | 583 | (limit - setpoint) | 1); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 584 | pos_ratio = x; |
| 585 | pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT; |
| 586 | pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT; |
| 587 | pos_ratio += 1 << RATELIMIT_CALC_SHIFT; |
| 588 | |
| 589 | return clamp(pos_ratio, 0LL, 2LL << RATELIMIT_CALC_SHIFT); |
| 590 | } |
| 591 | |
| 592 | /* |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 593 | * Dirty position control. |
| 594 | * |
| 595 | * (o) global/bdi setpoints |
| 596 | * |
| 597 | * We want the dirty pages be balanced around the global/bdi setpoints. |
| 598 | * When the number of dirty pages is higher/lower than the setpoint, the |
| 599 | * dirty position control ratio (and hence task dirty ratelimit) will be |
| 600 | * decreased/increased to bring the dirty pages back to the setpoint. |
| 601 | * |
| 602 | * pos_ratio = 1 << RATELIMIT_CALC_SHIFT |
| 603 | * |
| 604 | * if (dirty < setpoint) scale up pos_ratio |
| 605 | * if (dirty > setpoint) scale down pos_ratio |
| 606 | * |
| 607 | * if (bdi_dirty < bdi_setpoint) scale up pos_ratio |
| 608 | * if (bdi_dirty > bdi_setpoint) scale down pos_ratio |
| 609 | * |
| 610 | * task_ratelimit = dirty_ratelimit * pos_ratio >> RATELIMIT_CALC_SHIFT |
| 611 | * |
| 612 | * (o) global control line |
| 613 | * |
| 614 | * ^ pos_ratio |
| 615 | * | |
| 616 | * | |<===== global dirty control scope ======>| |
| 617 | * 2.0 .............* |
| 618 | * | .* |
| 619 | * | . * |
| 620 | * | . * |
| 621 | * | . * |
| 622 | * | . * |
| 623 | * | . * |
| 624 | * 1.0 ................................* |
| 625 | * | . . * |
| 626 | * | . . * |
| 627 | * | . . * |
| 628 | * | . . * |
| 629 | * | . . * |
| 630 | * 0 +------------.------------------.----------------------*-------------> |
| 631 | * freerun^ setpoint^ limit^ dirty pages |
| 632 | * |
| 633 | * (o) bdi control line |
| 634 | * |
| 635 | * ^ pos_ratio |
| 636 | * | |
| 637 | * | * |
| 638 | * | * |
| 639 | * | * |
| 640 | * | * |
| 641 | * | * |<=========== span ============>| |
| 642 | * 1.0 .......................* |
| 643 | * | . * |
| 644 | * | . * |
| 645 | * | . * |
| 646 | * | . * |
| 647 | * | . * |
| 648 | * | . * |
| 649 | * | . * |
| 650 | * | . * |
| 651 | * | . * |
| 652 | * | . * |
| 653 | * | . * |
| 654 | * 1/4 ...............................................* * * * * * * * * * * * |
| 655 | * | . . |
| 656 | * | . . |
| 657 | * | . . |
| 658 | * 0 +----------------------.-------------------------------.-------------> |
| 659 | * bdi_setpoint^ x_intercept^ |
| 660 | * |
| 661 | * The bdi control line won't drop below pos_ratio=1/4, so that bdi_dirty can |
| 662 | * be smoothly throttled down to normal if it starts high in situations like |
| 663 | * - start writing to a slow SD card and a fast disk at the same time. The SD |
| 664 | * card's bdi_dirty may rush to many times higher than bdi_setpoint. |
| 665 | * - the bdi dirty thresh drops quickly due to change of JBOD workload |
| 666 | */ |
| 667 | static unsigned long bdi_position_ratio(struct backing_dev_info *bdi, |
| 668 | unsigned long thresh, |
| 669 | unsigned long bg_thresh, |
| 670 | unsigned long dirty, |
| 671 | unsigned long bdi_thresh, |
| 672 | unsigned long bdi_dirty) |
| 673 | { |
| 674 | unsigned long write_bw = bdi->avg_write_bandwidth; |
| 675 | unsigned long freerun = dirty_freerun_ceiling(thresh, bg_thresh); |
| 676 | unsigned long limit = hard_dirty_limit(thresh); |
| 677 | unsigned long x_intercept; |
| 678 | unsigned long setpoint; /* dirty pages' target balance point */ |
| 679 | unsigned long bdi_setpoint; |
| 680 | unsigned long span; |
| 681 | long long pos_ratio; /* for scaling up/down the rate limit */ |
| 682 | long x; |
| 683 | |
| 684 | if (unlikely(dirty >= limit)) |
| 685 | return 0; |
| 686 | |
| 687 | /* |
| 688 | * global setpoint |
| 689 | * |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 690 | * See comment for pos_ratio_polynom(). |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 691 | */ |
| 692 | setpoint = (freerun + limit) / 2; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 693 | pos_ratio = pos_ratio_polynom(setpoint, dirty, limit); |
| 694 | |
| 695 | /* |
| 696 | * The strictlimit feature is a tool preventing mistrusted filesystems |
| 697 | * from growing a large number of dirty pages before throttling. For |
| 698 | * such filesystems balance_dirty_pages always checks bdi counters |
| 699 | * against bdi limits. Even if global "nr_dirty" is under "freerun". |
| 700 | * This is especially important for fuse which sets bdi->max_ratio to |
| 701 | * 1% by default. Without strictlimit feature, fuse writeback may |
| 702 | * consume arbitrary amount of RAM because it is accounted in |
| 703 | * NR_WRITEBACK_TEMP which is not involved in calculating "nr_dirty". |
| 704 | * |
| 705 | * Here, in bdi_position_ratio(), we calculate pos_ratio based on |
| 706 | * two values: bdi_dirty and bdi_thresh. Let's consider an example: |
| 707 | * total amount of RAM is 16GB, bdi->max_ratio is equal to 1%, global |
| 708 | * limits are set by default to 10% and 20% (background and throttle). |
| 709 | * Then bdi_thresh is 1% of 20% of 16GB. This amounts to ~8K pages. |
| 710 | * bdi_dirty_limit(bdi, bg_thresh) is about ~4K pages. bdi_setpoint is |
| 711 | * about ~6K pages (as the average of background and throttle bdi |
| 712 | * limits). The 3rd order polynomial will provide positive feedback if |
| 713 | * bdi_dirty is under bdi_setpoint and vice versa. |
| 714 | * |
| 715 | * Note, that we cannot use global counters in these calculations |
| 716 | * because we want to throttle process writing to a strictlimit BDI |
| 717 | * much earlier than global "freerun" is reached (~23MB vs. ~2.3GB |
| 718 | * in the example above). |
| 719 | */ |
| 720 | if (unlikely(bdi->capabilities & BDI_CAP_STRICTLIMIT)) { |
| 721 | long long bdi_pos_ratio; |
| 722 | unsigned long bdi_bg_thresh; |
| 723 | |
| 724 | if (bdi_dirty < 8) |
| 725 | return min_t(long long, pos_ratio * 2, |
| 726 | 2 << RATELIMIT_CALC_SHIFT); |
| 727 | |
| 728 | if (bdi_dirty >= bdi_thresh) |
| 729 | return 0; |
| 730 | |
| 731 | bdi_bg_thresh = div_u64((u64)bdi_thresh * bg_thresh, thresh); |
| 732 | bdi_setpoint = dirty_freerun_ceiling(bdi_thresh, |
| 733 | bdi_bg_thresh); |
| 734 | |
| 735 | if (bdi_setpoint == 0 || bdi_setpoint == bdi_thresh) |
| 736 | return 0; |
| 737 | |
| 738 | bdi_pos_ratio = pos_ratio_polynom(bdi_setpoint, bdi_dirty, |
| 739 | bdi_thresh); |
| 740 | |
| 741 | /* |
| 742 | * Typically, for strictlimit case, bdi_setpoint << setpoint |
| 743 | * and pos_ratio >> bdi_pos_ratio. In the other words global |
| 744 | * state ("dirty") is not limiting factor and we have to |
| 745 | * make decision based on bdi counters. But there is an |
| 746 | * important case when global pos_ratio should get precedence: |
| 747 | * global limits are exceeded (e.g. due to activities on other |
| 748 | * BDIs) while given strictlimit BDI is below limit. |
| 749 | * |
| 750 | * "pos_ratio * bdi_pos_ratio" would work for the case above, |
| 751 | * but it would look too non-natural for the case of all |
| 752 | * activity in the system coming from a single strictlimit BDI |
| 753 | * with bdi->max_ratio == 100%. |
| 754 | * |
| 755 | * Note that min() below somewhat changes the dynamics of the |
| 756 | * control system. Normally, pos_ratio value can be well over 3 |
| 757 | * (when globally we are at freerun and bdi is well below bdi |
| 758 | * setpoint). Now the maximum pos_ratio in the same situation |
| 759 | * is 2. We might want to tweak this if we observe the control |
| 760 | * system is too slow to adapt. |
| 761 | */ |
| 762 | return min(pos_ratio, bdi_pos_ratio); |
| 763 | } |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 764 | |
| 765 | /* |
| 766 | * We have computed basic pos_ratio above based on global situation. If |
| 767 | * the bdi is over/under its share of dirty pages, we want to scale |
| 768 | * pos_ratio further down/up. That is done by the following mechanism. |
| 769 | */ |
| 770 | |
| 771 | /* |
| 772 | * bdi setpoint |
| 773 | * |
| 774 | * f(bdi_dirty) := 1.0 + k * (bdi_dirty - bdi_setpoint) |
| 775 | * |
| 776 | * x_intercept - bdi_dirty |
| 777 | * := -------------------------- |
| 778 | * x_intercept - bdi_setpoint |
| 779 | * |
| 780 | * The main bdi control line is a linear function that subjects to |
| 781 | * |
| 782 | * (1) f(bdi_setpoint) = 1.0 |
| 783 | * (2) k = - 1 / (8 * write_bw) (in single bdi case) |
| 784 | * or equally: x_intercept = bdi_setpoint + 8 * write_bw |
| 785 | * |
| 786 | * For single bdi case, the dirty pages are observed to fluctuate |
| 787 | * regularly within range |
| 788 | * [bdi_setpoint - write_bw/2, bdi_setpoint + write_bw/2] |
| 789 | * for various filesystems, where (2) can yield in a reasonable 12.5% |
| 790 | * fluctuation range for pos_ratio. |
| 791 | * |
| 792 | * For JBOD case, bdi_thresh (not bdi_dirty!) could fluctuate up to its |
| 793 | * own size, so move the slope over accordingly and choose a slope that |
| 794 | * yields 100% pos_ratio fluctuation on suddenly doubled bdi_thresh. |
| 795 | */ |
| 796 | if (unlikely(bdi_thresh > thresh)) |
| 797 | bdi_thresh = thresh; |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 798 | /* |
| 799 | * It's very possible that bdi_thresh is close to 0 not because the |
| 800 | * device is slow, but that it has remained inactive for long time. |
| 801 | * Honour such devices a reasonable good (hopefully IO efficient) |
| 802 | * threshold, so that the occasional writes won't be blocked and active |
| 803 | * writes can rampup the threshold quickly. |
| 804 | */ |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 805 | bdi_thresh = max(bdi_thresh, (limit - dirty) / 8); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 806 | /* |
| 807 | * scale global setpoint to bdi's: |
| 808 | * bdi_setpoint = setpoint * bdi_thresh / thresh |
| 809 | */ |
Tejun Heo | 464d138 | 2015-04-21 16:49:13 -0400 | [diff] [blame] | 810 | x = div_u64((u64)bdi_thresh << 16, thresh | 1); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 811 | bdi_setpoint = setpoint * (u64)x >> 16; |
| 812 | /* |
| 813 | * Use span=(8*write_bw) in single bdi case as indicated by |
| 814 | * (thresh - bdi_thresh ~= 0) and transit to bdi_thresh in JBOD case. |
| 815 | * |
| 816 | * bdi_thresh thresh - bdi_thresh |
| 817 | * span = ---------- * (8 * write_bw) + ------------------- * bdi_thresh |
| 818 | * thresh thresh |
| 819 | */ |
| 820 | span = (thresh - bdi_thresh + 8 * write_bw) * (u64)x >> 16; |
| 821 | x_intercept = bdi_setpoint + span; |
| 822 | |
| 823 | if (bdi_dirty < x_intercept - span / 4) { |
Rik van Riel | d5c9fde | 2014-05-06 12:50:01 -0700 | [diff] [blame] | 824 | pos_ratio = div64_u64(pos_ratio * (x_intercept - bdi_dirty), |
Tejun Heo | 464d138 | 2015-04-21 16:49:13 -0400 | [diff] [blame] | 825 | (x_intercept - bdi_setpoint) | 1); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 826 | } else |
| 827 | pos_ratio /= 4; |
| 828 | |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 829 | /* |
| 830 | * bdi reserve area, safeguard against dirty pool underrun and disk idle |
| 831 | * It may push the desired control point of global dirty pages higher |
| 832 | * than setpoint. |
| 833 | */ |
| 834 | x_intercept = bdi_thresh / 2; |
| 835 | if (bdi_dirty < x_intercept) { |
Wu Fengguang | 50657fc | 2011-10-11 17:06:33 -0600 | [diff] [blame] | 836 | if (bdi_dirty > x_intercept / 8) |
| 837 | pos_ratio = div_u64(pos_ratio * x_intercept, bdi_dirty); |
| 838 | else |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 839 | pos_ratio *= 8; |
| 840 | } |
| 841 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 842 | return pos_ratio; |
| 843 | } |
| 844 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 845 | static void bdi_update_write_bandwidth(struct backing_dev_info *bdi, |
| 846 | unsigned long elapsed, |
| 847 | unsigned long written) |
| 848 | { |
| 849 | const unsigned long period = roundup_pow_of_two(3 * HZ); |
| 850 | unsigned long avg = bdi->avg_write_bandwidth; |
| 851 | unsigned long old = bdi->write_bandwidth; |
| 852 | u64 bw; |
| 853 | |
| 854 | /* |
| 855 | * bw = written * HZ / elapsed |
| 856 | * |
| 857 | * bw * elapsed + write_bandwidth * (period - elapsed) |
| 858 | * write_bandwidth = --------------------------------------------------- |
| 859 | * period |
Tejun Heo | c72efb6 | 2015-03-23 00:18:48 -0400 | [diff] [blame] | 860 | * |
| 861 | * @written may have decreased due to account_page_redirty(). |
| 862 | * Avoid underflowing @bw calculation. |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 863 | */ |
Tejun Heo | c72efb6 | 2015-03-23 00:18:48 -0400 | [diff] [blame] | 864 | bw = written - min(written, bdi->written_stamp); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 865 | bw *= HZ; |
| 866 | if (unlikely(elapsed > period)) { |
| 867 | do_div(bw, elapsed); |
| 868 | avg = bw; |
| 869 | goto out; |
| 870 | } |
| 871 | bw += (u64)bdi->write_bandwidth * (period - elapsed); |
| 872 | bw >>= ilog2(period); |
| 873 | |
| 874 | /* |
| 875 | * one more level of smoothing, for filtering out sudden spikes |
| 876 | */ |
| 877 | if (avg > old && old >= (unsigned long)bw) |
| 878 | avg -= (avg - old) >> 3; |
| 879 | |
| 880 | if (avg < old && old <= (unsigned long)bw) |
| 881 | avg += (old - avg) >> 3; |
| 882 | |
| 883 | out: |
| 884 | bdi->write_bandwidth = bw; |
| 885 | bdi->avg_write_bandwidth = avg; |
| 886 | } |
| 887 | |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 888 | /* |
| 889 | * The global dirtyable memory and dirty threshold could be suddenly knocked |
| 890 | * down by a large amount (eg. on the startup of KVM in a swapless system). |
| 891 | * This may throw the system into deep dirty exceeded state and throttle |
| 892 | * heavy/light dirtiers alike. To retain good responsiveness, maintain |
| 893 | * global_dirty_limit for tracking slowly down to the knocked down dirty |
| 894 | * threshold. |
| 895 | */ |
| 896 | static void update_dirty_limit(unsigned long thresh, unsigned long dirty) |
| 897 | { |
| 898 | unsigned long limit = global_dirty_limit; |
| 899 | |
| 900 | /* |
| 901 | * Follow up in one step. |
| 902 | */ |
| 903 | if (limit < thresh) { |
| 904 | limit = thresh; |
| 905 | goto update; |
| 906 | } |
| 907 | |
| 908 | /* |
| 909 | * Follow down slowly. Use the higher one as the target, because thresh |
| 910 | * may drop below dirty. This is exactly the reason to introduce |
| 911 | * global_dirty_limit which is guaranteed to lie above the dirty pages. |
| 912 | */ |
| 913 | thresh = max(thresh, dirty); |
| 914 | if (limit > thresh) { |
| 915 | limit -= (limit - thresh) >> 5; |
| 916 | goto update; |
| 917 | } |
| 918 | return; |
| 919 | update: |
| 920 | global_dirty_limit = limit; |
| 921 | } |
| 922 | |
| 923 | static void global_update_bandwidth(unsigned long thresh, |
| 924 | unsigned long dirty, |
| 925 | unsigned long now) |
| 926 | { |
| 927 | static DEFINE_SPINLOCK(dirty_lock); |
Tejun Heo | 7d70e15 | 2015-03-04 10:37:43 -0500 | [diff] [blame] | 928 | static unsigned long update_time = INITIAL_JIFFIES; |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 929 | |
| 930 | /* |
| 931 | * check locklessly first to optimize away locking for the most time |
| 932 | */ |
| 933 | if (time_before(now, update_time + BANDWIDTH_INTERVAL)) |
| 934 | return; |
| 935 | |
| 936 | spin_lock(&dirty_lock); |
| 937 | if (time_after_eq(now, update_time + BANDWIDTH_INTERVAL)) { |
| 938 | update_dirty_limit(thresh, dirty); |
| 939 | update_time = now; |
| 940 | } |
| 941 | spin_unlock(&dirty_lock); |
| 942 | } |
| 943 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 944 | /* |
| 945 | * Maintain bdi->dirty_ratelimit, the base dirty throttle rate. |
| 946 | * |
| 947 | * Normal bdi tasks will be curbed at or below it in long term. |
| 948 | * Obviously it should be around (write_bw / N) when there are N dd tasks. |
| 949 | */ |
| 950 | static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi, |
| 951 | unsigned long thresh, |
| 952 | unsigned long bg_thresh, |
| 953 | unsigned long dirty, |
| 954 | unsigned long bdi_thresh, |
| 955 | unsigned long bdi_dirty, |
| 956 | unsigned long dirtied, |
| 957 | unsigned long elapsed) |
| 958 | { |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 959 | unsigned long freerun = dirty_freerun_ceiling(thresh, bg_thresh); |
| 960 | unsigned long limit = hard_dirty_limit(thresh); |
| 961 | unsigned long setpoint = (freerun + limit) / 2; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 962 | unsigned long write_bw = bdi->avg_write_bandwidth; |
| 963 | unsigned long dirty_ratelimit = bdi->dirty_ratelimit; |
| 964 | unsigned long dirty_rate; |
| 965 | unsigned long task_ratelimit; |
| 966 | unsigned long balanced_dirty_ratelimit; |
| 967 | unsigned long pos_ratio; |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 968 | unsigned long step; |
| 969 | unsigned long x; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 970 | |
| 971 | /* |
| 972 | * The dirty rate will match the writeout rate in long term, except |
| 973 | * when dirty pages are truncated by userspace or re-dirtied by FS. |
| 974 | */ |
| 975 | dirty_rate = (dirtied - bdi->dirtied_stamp) * HZ / elapsed; |
| 976 | |
| 977 | pos_ratio = bdi_position_ratio(bdi, thresh, bg_thresh, dirty, |
| 978 | bdi_thresh, bdi_dirty); |
| 979 | /* |
| 980 | * task_ratelimit reflects each dd's dirty rate for the past 200ms. |
| 981 | */ |
| 982 | task_ratelimit = (u64)dirty_ratelimit * |
| 983 | pos_ratio >> RATELIMIT_CALC_SHIFT; |
| 984 | task_ratelimit++; /* it helps rampup dirty_ratelimit from tiny values */ |
| 985 | |
| 986 | /* |
| 987 | * A linear estimation of the "balanced" throttle rate. The theory is, |
| 988 | * if there are N dd tasks, each throttled at task_ratelimit, the bdi's |
| 989 | * dirty_rate will be measured to be (N * task_ratelimit). So the below |
| 990 | * formula will yield the balanced rate limit (write_bw / N). |
| 991 | * |
| 992 | * Note that the expanded form is not a pure rate feedback: |
| 993 | * rate_(i+1) = rate_(i) * (write_bw / dirty_rate) (1) |
| 994 | * but also takes pos_ratio into account: |
| 995 | * rate_(i+1) = rate_(i) * (write_bw / dirty_rate) * pos_ratio (2) |
| 996 | * |
| 997 | * (1) is not realistic because pos_ratio also takes part in balancing |
| 998 | * the dirty rate. Consider the state |
| 999 | * pos_ratio = 0.5 (3) |
| 1000 | * rate = 2 * (write_bw / N) (4) |
| 1001 | * If (1) is used, it will stuck in that state! Because each dd will |
| 1002 | * be throttled at |
| 1003 | * task_ratelimit = pos_ratio * rate = (write_bw / N) (5) |
| 1004 | * yielding |
| 1005 | * dirty_rate = N * task_ratelimit = write_bw (6) |
| 1006 | * put (6) into (1) we get |
| 1007 | * rate_(i+1) = rate_(i) (7) |
| 1008 | * |
| 1009 | * So we end up using (2) to always keep |
| 1010 | * rate_(i+1) ~= (write_bw / N) (8) |
| 1011 | * regardless of the value of pos_ratio. As long as (8) is satisfied, |
| 1012 | * pos_ratio is able to drive itself to 1.0, which is not only where |
| 1013 | * the dirty count meet the setpoint, but also where the slope of |
| 1014 | * pos_ratio is most flat and hence task_ratelimit is least fluctuated. |
| 1015 | */ |
| 1016 | balanced_dirty_ratelimit = div_u64((u64)task_ratelimit * write_bw, |
| 1017 | dirty_rate | 1); |
Wu Fengguang | bdaac49 | 2011-08-03 14:30:36 -0600 | [diff] [blame] | 1018 | /* |
| 1019 | * balanced_dirty_ratelimit ~= (write_bw / N) <= write_bw |
| 1020 | */ |
| 1021 | if (unlikely(balanced_dirty_ratelimit > write_bw)) |
| 1022 | balanced_dirty_ratelimit = write_bw; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1023 | |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1024 | /* |
| 1025 | * We could safely do this and return immediately: |
| 1026 | * |
| 1027 | * bdi->dirty_ratelimit = balanced_dirty_ratelimit; |
| 1028 | * |
| 1029 | * However to get a more stable dirty_ratelimit, the below elaborated |
Wanpeng Li | 331cbde | 2012-06-09 11:10:55 +0800 | [diff] [blame] | 1030 | * code makes use of task_ratelimit to filter out singular points and |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1031 | * limit the step size. |
| 1032 | * |
| 1033 | * The below code essentially only uses the relative value of |
| 1034 | * |
| 1035 | * task_ratelimit - dirty_ratelimit |
| 1036 | * = (pos_ratio - 1) * dirty_ratelimit |
| 1037 | * |
| 1038 | * which reflects the direction and size of dirty position error. |
| 1039 | */ |
| 1040 | |
| 1041 | /* |
| 1042 | * dirty_ratelimit will follow balanced_dirty_ratelimit iff |
| 1043 | * task_ratelimit is on the same side of dirty_ratelimit, too. |
| 1044 | * For example, when |
| 1045 | * - dirty_ratelimit > balanced_dirty_ratelimit |
| 1046 | * - dirty_ratelimit > task_ratelimit (dirty pages are above setpoint) |
| 1047 | * lowering dirty_ratelimit will help meet both the position and rate |
| 1048 | * control targets. Otherwise, don't update dirty_ratelimit if it will |
| 1049 | * only help meet the rate target. After all, what the users ultimately |
| 1050 | * feel and care are stable dirty rate and small position error. |
| 1051 | * |
| 1052 | * |task_ratelimit - dirty_ratelimit| is used to limit the step size |
Wanpeng Li | 331cbde | 2012-06-09 11:10:55 +0800 | [diff] [blame] | 1053 | * and filter out the singular points of balanced_dirty_ratelimit. Which |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1054 | * keeps jumping around randomly and can even leap far away at times |
| 1055 | * due to the small 200ms estimation period of dirty_rate (we want to |
| 1056 | * keep that period small to reduce time lags). |
| 1057 | */ |
| 1058 | step = 0; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1059 | |
| 1060 | /* |
| 1061 | * For strictlimit case, calculations above were based on bdi counters |
| 1062 | * and limits (starting from pos_ratio = bdi_position_ratio() and up to |
| 1063 | * balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate). |
| 1064 | * Hence, to calculate "step" properly, we have to use bdi_dirty as |
| 1065 | * "dirty" and bdi_setpoint as "setpoint". |
| 1066 | * |
| 1067 | * We rampup dirty_ratelimit forcibly if bdi_dirty is low because |
| 1068 | * it's possible that bdi_thresh is close to zero due to inactivity |
| 1069 | * of backing device (see the implementation of bdi_dirty_limit()). |
| 1070 | */ |
| 1071 | if (unlikely(bdi->capabilities & BDI_CAP_STRICTLIMIT)) { |
| 1072 | dirty = bdi_dirty; |
| 1073 | if (bdi_dirty < 8) |
| 1074 | setpoint = bdi_dirty + 1; |
| 1075 | else |
| 1076 | setpoint = (bdi_thresh + |
| 1077 | bdi_dirty_limit(bdi, bg_thresh)) / 2; |
| 1078 | } |
| 1079 | |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1080 | if (dirty < setpoint) { |
Mark Rustad | 7c80996 | 2014-10-09 15:28:15 -0700 | [diff] [blame] | 1081 | x = min3(bdi->balanced_dirty_ratelimit, |
| 1082 | balanced_dirty_ratelimit, task_ratelimit); |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1083 | if (dirty_ratelimit < x) |
| 1084 | step = x - dirty_ratelimit; |
| 1085 | } else { |
Mark Rustad | 7c80996 | 2014-10-09 15:28:15 -0700 | [diff] [blame] | 1086 | x = max3(bdi->balanced_dirty_ratelimit, |
| 1087 | balanced_dirty_ratelimit, task_ratelimit); |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1088 | if (dirty_ratelimit > x) |
| 1089 | step = dirty_ratelimit - x; |
| 1090 | } |
| 1091 | |
| 1092 | /* |
| 1093 | * Don't pursue 100% rate matching. It's impossible since the balanced |
| 1094 | * rate itself is constantly fluctuating. So decrease the track speed |
| 1095 | * when it gets close to the target. Helps eliminate pointless tremors. |
| 1096 | */ |
| 1097 | step >>= dirty_ratelimit / (2 * step + 1); |
| 1098 | /* |
| 1099 | * Limit the tracking speed to avoid overshooting. |
| 1100 | */ |
| 1101 | step = (step + 7) / 8; |
| 1102 | |
| 1103 | if (dirty_ratelimit < balanced_dirty_ratelimit) |
| 1104 | dirty_ratelimit += step; |
| 1105 | else |
| 1106 | dirty_ratelimit -= step; |
| 1107 | |
| 1108 | bdi->dirty_ratelimit = max(dirty_ratelimit, 1UL); |
| 1109 | bdi->balanced_dirty_ratelimit = balanced_dirty_ratelimit; |
Wu Fengguang | b48c104 | 2011-03-02 17:22:49 -0600 | [diff] [blame] | 1110 | |
| 1111 | trace_bdi_dirty_ratelimit(bdi, dirty_rate, task_ratelimit); |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1112 | } |
| 1113 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1114 | void __bdi_update_bandwidth(struct backing_dev_info *bdi, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1115 | unsigned long thresh, |
Wu Fengguang | af6a311 | 2011-10-03 20:46:17 -0600 | [diff] [blame] | 1116 | unsigned long bg_thresh, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1117 | unsigned long dirty, |
| 1118 | unsigned long bdi_thresh, |
| 1119 | unsigned long bdi_dirty, |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1120 | unsigned long start_time) |
| 1121 | { |
| 1122 | unsigned long now = jiffies; |
| 1123 | unsigned long elapsed = now - bdi->bw_time_stamp; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1124 | unsigned long dirtied; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1125 | unsigned long written; |
| 1126 | |
| 1127 | /* |
| 1128 | * rate-limit, only update once every 200ms. |
| 1129 | */ |
| 1130 | if (elapsed < BANDWIDTH_INTERVAL) |
| 1131 | return; |
| 1132 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1133 | dirtied = percpu_counter_read(&bdi->bdi_stat[BDI_DIRTIED]); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1134 | written = percpu_counter_read(&bdi->bdi_stat[BDI_WRITTEN]); |
| 1135 | |
| 1136 | /* |
| 1137 | * Skip quiet periods when disk bandwidth is under-utilized. |
| 1138 | * (at least 1s idle time between two flusher runs) |
| 1139 | */ |
| 1140 | if (elapsed > HZ && time_before(bdi->bw_time_stamp, start_time)) |
| 1141 | goto snapshot; |
| 1142 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1143 | if (thresh) { |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1144 | global_update_bandwidth(thresh, dirty, now); |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1145 | bdi_update_dirty_ratelimit(bdi, thresh, bg_thresh, dirty, |
| 1146 | bdi_thresh, bdi_dirty, |
| 1147 | dirtied, elapsed); |
| 1148 | } |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1149 | bdi_update_write_bandwidth(bdi, elapsed, written); |
| 1150 | |
| 1151 | snapshot: |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1152 | bdi->dirtied_stamp = dirtied; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1153 | bdi->written_stamp = written; |
| 1154 | bdi->bw_time_stamp = now; |
| 1155 | } |
| 1156 | |
| 1157 | static void bdi_update_bandwidth(struct backing_dev_info *bdi, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1158 | unsigned long thresh, |
Wu Fengguang | af6a311 | 2011-10-03 20:46:17 -0600 | [diff] [blame] | 1159 | unsigned long bg_thresh, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1160 | unsigned long dirty, |
| 1161 | unsigned long bdi_thresh, |
| 1162 | unsigned long bdi_dirty, |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1163 | unsigned long start_time) |
| 1164 | { |
| 1165 | if (time_is_after_eq_jiffies(bdi->bw_time_stamp + BANDWIDTH_INTERVAL)) |
| 1166 | return; |
| 1167 | spin_lock(&bdi->wb.list_lock); |
Wu Fengguang | af6a311 | 2011-10-03 20:46:17 -0600 | [diff] [blame] | 1168 | __bdi_update_bandwidth(bdi, thresh, bg_thresh, dirty, |
| 1169 | bdi_thresh, bdi_dirty, start_time); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1170 | spin_unlock(&bdi->wb.list_lock); |
| 1171 | } |
| 1172 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1173 | /* |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1174 | * After a task dirtied this many pages, balance_dirty_pages_ratelimited() |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1175 | * will look to see if it needs to start dirty throttling. |
| 1176 | * |
| 1177 | * If dirty_poll_interval is too low, big NUMA machines will call the expensive |
| 1178 | * global_page_state() too often. So scale it near-sqrt to the safety margin |
| 1179 | * (the number of pages we may dirty without exceeding the dirty limits). |
| 1180 | */ |
| 1181 | static unsigned long dirty_poll_interval(unsigned long dirty, |
| 1182 | unsigned long thresh) |
| 1183 | { |
| 1184 | if (thresh > dirty) |
| 1185 | return 1UL << (ilog2(thresh - dirty) >> 1); |
| 1186 | |
| 1187 | return 1; |
| 1188 | } |
| 1189 | |
Fengguang Wu | e3b6c65 | 2013-10-16 13:47:03 -0700 | [diff] [blame] | 1190 | static unsigned long bdi_max_pause(struct backing_dev_info *bdi, |
| 1191 | unsigned long bdi_dirty) |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1192 | { |
Fengguang Wu | e3b6c65 | 2013-10-16 13:47:03 -0700 | [diff] [blame] | 1193 | unsigned long bw = bdi->avg_write_bandwidth; |
| 1194 | unsigned long t; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1195 | |
| 1196 | /* |
| 1197 | * Limit pause time for small memory systems. If sleeping for too long |
| 1198 | * time, a small pool of dirty/writeback pages may go empty and disk go |
| 1199 | * idle. |
| 1200 | * |
| 1201 | * 8 serves as the safety ratio. |
| 1202 | */ |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1203 | t = bdi_dirty / (1 + bw / roundup_pow_of_two(1 + HZ / 8)); |
| 1204 | t++; |
| 1205 | |
Fengguang Wu | e3b6c65 | 2013-10-16 13:47:03 -0700 | [diff] [blame] | 1206 | return min_t(unsigned long, t, MAX_PAUSE); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1207 | } |
| 1208 | |
| 1209 | static long bdi_min_pause(struct backing_dev_info *bdi, |
| 1210 | long max_pause, |
| 1211 | unsigned long task_ratelimit, |
| 1212 | unsigned long dirty_ratelimit, |
| 1213 | int *nr_dirtied_pause) |
| 1214 | { |
| 1215 | long hi = ilog2(bdi->avg_write_bandwidth); |
| 1216 | long lo = ilog2(bdi->dirty_ratelimit); |
| 1217 | long t; /* target pause */ |
| 1218 | long pause; /* estimated next pause */ |
| 1219 | int pages; /* target nr_dirtied_pause */ |
| 1220 | |
| 1221 | /* target for 10ms pause on 1-dd case */ |
| 1222 | t = max(1, HZ / 100); |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1223 | |
| 1224 | /* |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1225 | * Scale up pause time for concurrent dirtiers in order to reduce CPU |
| 1226 | * overheads. |
| 1227 | * |
| 1228 | * (N * 10ms) on 2^N concurrent tasks. |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1229 | */ |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1230 | if (hi > lo) |
| 1231 | t += (hi - lo) * (10 * HZ) / 1024; |
| 1232 | |
| 1233 | /* |
| 1234 | * This is a bit convoluted. We try to base the next nr_dirtied_pause |
| 1235 | * on the much more stable dirty_ratelimit. However the next pause time |
| 1236 | * will be computed based on task_ratelimit and the two rate limits may |
| 1237 | * depart considerably at some time. Especially if task_ratelimit goes |
| 1238 | * below dirty_ratelimit/2 and the target pause is max_pause, the next |
| 1239 | * pause time will be max_pause*2 _trimmed down_ to max_pause. As a |
| 1240 | * result task_ratelimit won't be executed faithfully, which could |
| 1241 | * eventually bring down dirty_ratelimit. |
| 1242 | * |
| 1243 | * We apply two rules to fix it up: |
| 1244 | * 1) try to estimate the next pause time and if necessary, use a lower |
| 1245 | * nr_dirtied_pause so as not to exceed max_pause. When this happens, |
| 1246 | * nr_dirtied_pause will be "dancing" with task_ratelimit. |
| 1247 | * 2) limit the target pause time to max_pause/2, so that the normal |
| 1248 | * small fluctuations of task_ratelimit won't trigger rule (1) and |
| 1249 | * nr_dirtied_pause will remain as stable as dirty_ratelimit. |
| 1250 | */ |
| 1251 | t = min(t, 1 + max_pause / 2); |
| 1252 | pages = dirty_ratelimit * t / roundup_pow_of_two(HZ); |
| 1253 | |
Wu Fengguang | 5b9b357 | 2011-12-06 13:17:17 -0600 | [diff] [blame] | 1254 | /* |
| 1255 | * Tiny nr_dirtied_pause is found to hurt I/O performance in the test |
| 1256 | * case fio-mmap-randwrite-64k, which does 16*{sync read, async write}. |
| 1257 | * When the 16 consecutive reads are often interrupted by some dirty |
| 1258 | * throttling pause during the async writes, cfq will go into idles |
| 1259 | * (deadline is fine). So push nr_dirtied_pause as high as possible |
| 1260 | * until reaches DIRTY_POLL_THRESH=32 pages. |
| 1261 | */ |
| 1262 | if (pages < DIRTY_POLL_THRESH) { |
| 1263 | t = max_pause; |
| 1264 | pages = dirty_ratelimit * t / roundup_pow_of_two(HZ); |
| 1265 | if (pages > DIRTY_POLL_THRESH) { |
| 1266 | pages = DIRTY_POLL_THRESH; |
| 1267 | t = HZ * DIRTY_POLL_THRESH / dirty_ratelimit; |
| 1268 | } |
| 1269 | } |
| 1270 | |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1271 | pause = HZ * pages / (task_ratelimit + 1); |
| 1272 | if (pause > max_pause) { |
| 1273 | t = max_pause; |
| 1274 | pages = task_ratelimit * t / roundup_pow_of_two(HZ); |
| 1275 | } |
| 1276 | |
| 1277 | *nr_dirtied_pause = pages; |
| 1278 | /* |
| 1279 | * The minimal pause time will normally be half the target pause time. |
| 1280 | */ |
Wu Fengguang | 5b9b357 | 2011-12-06 13:17:17 -0600 | [diff] [blame] | 1281 | return pages >= DIRTY_POLL_THRESH ? 1 + t / 2 : t; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1282 | } |
| 1283 | |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1284 | static inline void bdi_dirty_limits(struct backing_dev_info *bdi, |
| 1285 | unsigned long dirty_thresh, |
| 1286 | unsigned long background_thresh, |
| 1287 | unsigned long *bdi_dirty, |
| 1288 | unsigned long *bdi_thresh, |
| 1289 | unsigned long *bdi_bg_thresh) |
| 1290 | { |
| 1291 | unsigned long bdi_reclaimable; |
| 1292 | |
| 1293 | /* |
| 1294 | * bdi_thresh is not treated as some limiting factor as |
| 1295 | * dirty_thresh, due to reasons |
| 1296 | * - in JBOD setup, bdi_thresh can fluctuate a lot |
| 1297 | * - in a system with HDD and USB key, the USB key may somehow |
| 1298 | * go into state (bdi_dirty >> bdi_thresh) either because |
| 1299 | * bdi_dirty starts high, or because bdi_thresh drops low. |
| 1300 | * In this case we don't want to hard throttle the USB key |
| 1301 | * dirtiers for 100 seconds until bdi_dirty drops under |
| 1302 | * bdi_thresh. Instead the auxiliary bdi control line in |
| 1303 | * bdi_position_ratio() will let the dirtier task progress |
| 1304 | * at some rate <= (write_bw / 2) for bringing down bdi_dirty. |
| 1305 | */ |
| 1306 | *bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); |
| 1307 | |
| 1308 | if (bdi_bg_thresh) |
Maxim Patlasov | f678959 | 2014-07-30 16:08:21 -0700 | [diff] [blame] | 1309 | *bdi_bg_thresh = dirty_thresh ? div_u64((u64)*bdi_thresh * |
| 1310 | background_thresh, |
| 1311 | dirty_thresh) : 0; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1312 | |
| 1313 | /* |
| 1314 | * In order to avoid the stacked BDI deadlock we need |
| 1315 | * to ensure we accurately count the 'dirty' pages when |
| 1316 | * the threshold is low. |
| 1317 | * |
| 1318 | * Otherwise it would be possible to get thresh+n pages |
| 1319 | * reported dirty, even though there are thresh-m pages |
| 1320 | * actually dirty; with m+n sitting in the percpu |
| 1321 | * deltas. |
| 1322 | */ |
| 1323 | if (*bdi_thresh < 2 * bdi_stat_error(bdi)) { |
| 1324 | bdi_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE); |
| 1325 | *bdi_dirty = bdi_reclaimable + |
| 1326 | bdi_stat_sum(bdi, BDI_WRITEBACK); |
| 1327 | } else { |
| 1328 | bdi_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE); |
| 1329 | *bdi_dirty = bdi_reclaimable + |
| 1330 | bdi_stat(bdi, BDI_WRITEBACK); |
| 1331 | } |
| 1332 | } |
| 1333 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1334 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1335 | * balance_dirty_pages() must be called by processes which are generating dirty |
| 1336 | * 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] | 1337 | * the caller to wait once crossing the (background_thresh + dirty_thresh) / 2. |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 1338 | * If we're over `background_thresh' then the writeback threads are woken to |
| 1339 | * perform some writeout. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1340 | */ |
Wu Fengguang | 3a2e9a5 | 2009-09-23 21:56:00 +0800 | [diff] [blame] | 1341 | static void balance_dirty_pages(struct address_space *mapping, |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1342 | unsigned long pages_dirtied) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1343 | { |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1344 | unsigned long nr_reclaimable; /* = file_dirty + unstable_nfs */ |
Wu Fengguang | 7762741 | 2010-09-12 13:34:05 -0600 | [diff] [blame] | 1345 | unsigned long nr_dirty; /* = file_dirty + writeback + unstable_nfs */ |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 1346 | unsigned long background_thresh; |
| 1347 | unsigned long dirty_thresh; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1348 | long period; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1349 | long pause; |
| 1350 | long max_pause; |
| 1351 | long min_pause; |
| 1352 | int nr_dirtied_pause; |
Wu Fengguang | e50e372 | 2010-08-11 14:17:37 -0700 | [diff] [blame] | 1353 | bool dirty_exceeded = false; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1354 | unsigned long task_ratelimit; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1355 | unsigned long dirty_ratelimit; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1356 | unsigned long pos_ratio; |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 1357 | struct backing_dev_info *bdi = inode_to_bdi(mapping->host); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1358 | bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1359 | unsigned long start_time = jiffies; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1360 | |
| 1361 | for (;;) { |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1362 | unsigned long now = jiffies; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1363 | unsigned long uninitialized_var(bdi_thresh); |
| 1364 | unsigned long thresh; |
| 1365 | unsigned long uninitialized_var(bdi_dirty); |
| 1366 | unsigned long dirty; |
| 1367 | unsigned long bg_thresh; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1368 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1369 | /* |
| 1370 | * Unstable writes are a feature of certain networked |
| 1371 | * filesystems (i.e. NFS) in which data may have been |
| 1372 | * written to the server's write cache, but has not yet |
| 1373 | * been flushed to permanent storage. |
| 1374 | */ |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1375 | nr_reclaimable = global_page_state(NR_FILE_DIRTY) + |
| 1376 | global_page_state(NR_UNSTABLE_NFS); |
Wu Fengguang | 7762741 | 2010-09-12 13:34:05 -0600 | [diff] [blame] | 1377 | nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1378 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1379 | global_dirty_limits(&background_thresh, &dirty_thresh); |
| 1380 | |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1381 | if (unlikely(strictlimit)) { |
| 1382 | bdi_dirty_limits(bdi, dirty_thresh, background_thresh, |
| 1383 | &bdi_dirty, &bdi_thresh, &bg_thresh); |
| 1384 | |
| 1385 | dirty = bdi_dirty; |
| 1386 | thresh = bdi_thresh; |
| 1387 | } else { |
| 1388 | dirty = nr_dirty; |
| 1389 | thresh = dirty_thresh; |
| 1390 | bg_thresh = background_thresh; |
| 1391 | } |
| 1392 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1393 | /* |
| 1394 | * Throttle it only when the background writeback cannot |
| 1395 | * catch-up. This avoids (excessively) small writeouts |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1396 | * when the bdi limits are ramping up in case of !strictlimit. |
| 1397 | * |
| 1398 | * In strictlimit case make decision based on the bdi counters |
| 1399 | * and limits. Small writeouts when the bdi limits are ramping |
| 1400 | * up are the price we consciously pay for strictlimit-ing. |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1401 | */ |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1402 | if (dirty <= dirty_freerun_ceiling(thresh, bg_thresh)) { |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1403 | current->dirty_paused_when = now; |
| 1404 | current->nr_dirtied = 0; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1405 | current->nr_dirtied_pause = |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1406 | dirty_poll_interval(dirty, thresh); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1407 | break; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1408 | } |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1409 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1410 | if (unlikely(!writeback_in_progress(bdi))) |
| 1411 | bdi_start_background_writeback(bdi); |
| 1412 | |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1413 | if (!strictlimit) |
| 1414 | bdi_dirty_limits(bdi, dirty_thresh, background_thresh, |
| 1415 | &bdi_dirty, &bdi_thresh, NULL); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1416 | |
Wu Fengguang | 8279194 | 2011-12-03 21:26:01 -0600 | [diff] [blame] | 1417 | dirty_exceeded = (bdi_dirty > bdi_thresh) && |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1418 | ((nr_dirty > dirty_thresh) || strictlimit); |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1419 | if (dirty_exceeded && !bdi->dirty_exceeded) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1420 | bdi->dirty_exceeded = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1421 | |
Wu Fengguang | af6a311 | 2011-10-03 20:46:17 -0600 | [diff] [blame] | 1422 | bdi_update_bandwidth(bdi, dirty_thresh, background_thresh, |
| 1423 | nr_dirty, bdi_thresh, bdi_dirty, |
| 1424 | start_time); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1425 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1426 | dirty_ratelimit = bdi->dirty_ratelimit; |
| 1427 | pos_ratio = bdi_position_ratio(bdi, dirty_thresh, |
| 1428 | background_thresh, nr_dirty, |
| 1429 | bdi_thresh, bdi_dirty); |
Wu Fengguang | 3a73dbb | 2011-11-07 19:19:28 +0800 | [diff] [blame] | 1430 | task_ratelimit = ((u64)dirty_ratelimit * pos_ratio) >> |
| 1431 | RATELIMIT_CALC_SHIFT; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1432 | max_pause = bdi_max_pause(bdi, bdi_dirty); |
| 1433 | min_pause = bdi_min_pause(bdi, max_pause, |
| 1434 | task_ratelimit, dirty_ratelimit, |
| 1435 | &nr_dirtied_pause); |
| 1436 | |
Wu Fengguang | 3a73dbb | 2011-11-07 19:19:28 +0800 | [diff] [blame] | 1437 | if (unlikely(task_ratelimit == 0)) { |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1438 | period = max_pause; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1439 | pause = max_pause; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1440 | goto pause; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1441 | } |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1442 | period = HZ * pages_dirtied / task_ratelimit; |
| 1443 | pause = period; |
| 1444 | if (current->dirty_paused_when) |
| 1445 | pause -= now - current->dirty_paused_when; |
| 1446 | /* |
| 1447 | * For less than 1s think time (ext3/4 may block the dirtier |
| 1448 | * for up to 800ms from time to time on 1-HDD; so does xfs, |
| 1449 | * however at much less frequency), try to compensate it in |
| 1450 | * future periods by updating the virtual time; otherwise just |
| 1451 | * do a reset, as it may be a light dirtier. |
| 1452 | */ |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1453 | if (pause < min_pause) { |
Wu Fengguang | ece13ac3 | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1454 | trace_balance_dirty_pages(bdi, |
| 1455 | dirty_thresh, |
| 1456 | background_thresh, |
| 1457 | nr_dirty, |
| 1458 | bdi_thresh, |
| 1459 | bdi_dirty, |
| 1460 | dirty_ratelimit, |
| 1461 | task_ratelimit, |
| 1462 | pages_dirtied, |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1463 | period, |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1464 | min(pause, 0L), |
Wu Fengguang | ece13ac3 | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1465 | start_time); |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1466 | if (pause < -HZ) { |
| 1467 | current->dirty_paused_when = now; |
| 1468 | current->nr_dirtied = 0; |
| 1469 | } else if (period) { |
| 1470 | current->dirty_paused_when += period; |
| 1471 | current->nr_dirtied = 0; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1472 | } else if (current->nr_dirtied_pause <= pages_dirtied) |
| 1473 | current->nr_dirtied_pause += pages_dirtied; |
Wu Fengguang | 57fc978 | 2011-06-11 19:32:32 -0600 | [diff] [blame] | 1474 | break; |
| 1475 | } |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1476 | if (unlikely(pause > max_pause)) { |
| 1477 | /* for occasional dropped task_ratelimit */ |
| 1478 | now += min(pause - max_pause, max_pause); |
| 1479 | pause = max_pause; |
| 1480 | } |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1481 | |
| 1482 | pause: |
Wu Fengguang | ece13ac3 | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1483 | trace_balance_dirty_pages(bdi, |
| 1484 | dirty_thresh, |
| 1485 | background_thresh, |
| 1486 | nr_dirty, |
| 1487 | bdi_thresh, |
| 1488 | bdi_dirty, |
| 1489 | dirty_ratelimit, |
| 1490 | task_ratelimit, |
| 1491 | pages_dirtied, |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1492 | period, |
Wu Fengguang | ece13ac3 | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1493 | pause, |
| 1494 | start_time); |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1495 | __set_current_state(TASK_KILLABLE); |
Wu Fengguang | d25105e | 2009-10-09 12:40:42 +0200 | [diff] [blame] | 1496 | io_schedule_timeout(pause); |
Jens Axboe | 87c6a9b | 2009-09-17 19:59:14 +0200 | [diff] [blame] | 1497 | |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1498 | current->dirty_paused_when = now + pause; |
| 1499 | current->nr_dirtied = 0; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1500 | current->nr_dirtied_pause = nr_dirtied_pause; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1501 | |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1502 | /* |
Wu Fengguang | 1df64719 | 2011-11-13 19:47:32 -0600 | [diff] [blame] | 1503 | * This is typically equal to (nr_dirty < dirty_thresh) and can |
| 1504 | * also keep "1000+ dd on a slow USB stick" under control. |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1505 | */ |
Wu Fengguang | 1df64719 | 2011-11-13 19:47:32 -0600 | [diff] [blame] | 1506 | if (task_ratelimit) |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1507 | break; |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1508 | |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1509 | /* |
| 1510 | * In the case of an unresponding NFS server and the NFS dirty |
| 1511 | * pages exceeds dirty_thresh, give the other good bdi's a pipe |
| 1512 | * to go through, so that tasks on them still remain responsive. |
| 1513 | * |
| 1514 | * In theory 1 page is enough to keep the comsumer-producer |
| 1515 | * pipe going: the flusher cleans 1 page => the task dirties 1 |
| 1516 | * more page. However bdi_dirty has accounting errors. So use |
| 1517 | * the larger and more IO friendly bdi_stat_error. |
| 1518 | */ |
| 1519 | if (bdi_dirty <= bdi_stat_error(bdi)) |
| 1520 | break; |
| 1521 | |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1522 | if (fatal_signal_pending(current)) |
| 1523 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1524 | } |
| 1525 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1526 | if (!dirty_exceeded && bdi->dirty_exceeded) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1527 | bdi->dirty_exceeded = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1528 | |
| 1529 | if (writeback_in_progress(bdi)) |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 1530 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1531 | |
| 1532 | /* |
| 1533 | * In laptop mode, we wait until hitting the higher threshold before |
| 1534 | * starting background writeout, and then write out all the way down |
| 1535 | * to the lower threshold. So slow writers cause minimal disk activity. |
| 1536 | * |
| 1537 | * In normal mode, we start background writeout at the lower |
| 1538 | * background_thresh, to keep the amount of dirty memory low. |
| 1539 | */ |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1540 | if (laptop_mode) |
| 1541 | return; |
| 1542 | |
| 1543 | if (nr_reclaimable > background_thresh) |
Christoph Hellwig | c544419 | 2010-06-08 18:15:15 +0200 | [diff] [blame] | 1544 | bdi_start_background_writeback(bdi); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1545 | } |
| 1546 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1547 | static DEFINE_PER_CPU(int, bdp_ratelimits); |
Tejun Heo | 245b2e7 | 2009-06-24 15:13:48 +0900 | [diff] [blame] | 1548 | |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1549 | /* |
| 1550 | * Normal tasks are throttled by |
| 1551 | * loop { |
| 1552 | * dirty tsk->nr_dirtied_pause pages; |
| 1553 | * take a snap in balance_dirty_pages(); |
| 1554 | * } |
| 1555 | * However there is a worst case. If every task exit immediately when dirtied |
| 1556 | * (tsk->nr_dirtied_pause - 1) pages, balance_dirty_pages() will never be |
| 1557 | * called to throttle the page dirties. The solution is to save the not yet |
| 1558 | * throttled page dirties in dirty_throttle_leaks on task exit and charge them |
| 1559 | * randomly into the running tasks. This works well for the above worst case, |
| 1560 | * as the new task will pick up and accumulate the old task's leaked dirty |
| 1561 | * count and eventually get throttled. |
| 1562 | */ |
| 1563 | DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0; |
| 1564 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1565 | /** |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1566 | * balance_dirty_pages_ratelimited - balance dirty memory state |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 1567 | * @mapping: address_space which was dirtied |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1568 | * |
| 1569 | * Processes which are dirtying memory should call in here once for each page |
| 1570 | * which was newly dirtied. The function will periodically check the system's |
| 1571 | * dirty state and will initiate writeback if needed. |
| 1572 | * |
| 1573 | * On really big machines, get_writeback_state is expensive, so try to avoid |
| 1574 | * calling it too often (ratelimiting). But once we're over the dirty memory |
| 1575 | * limit we decrease the ratelimiting by a lot, to prevent individual processes |
| 1576 | * from overshooting the limit by (ratelimit_pages) each. |
| 1577 | */ |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1578 | void balance_dirty_pages_ratelimited(struct address_space *mapping) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1579 | { |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 1580 | struct backing_dev_info *bdi = inode_to_bdi(mapping->host); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1581 | int ratelimit; |
| 1582 | int *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1583 | |
Wu Fengguang | 36715ce | 2011-06-11 17:53:57 -0600 | [diff] [blame] | 1584 | if (!bdi_cap_account_dirty(bdi)) |
| 1585 | return; |
| 1586 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1587 | ratelimit = current->nr_dirtied_pause; |
| 1588 | if (bdi->dirty_exceeded) |
| 1589 | ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1590 | |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1591 | preempt_disable(); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1592 | /* |
| 1593 | * This prevents one CPU to accumulate too many dirtied pages without |
| 1594 | * calling into balance_dirty_pages(), which can happen when there are |
| 1595 | * 1000+ tasks, all of them start dirtying pages at exactly the same |
| 1596 | * time, hence all honoured too large initial task->nr_dirtied_pause. |
| 1597 | */ |
Christoph Lameter | 7c8e018 | 2014-06-04 16:07:56 -0700 | [diff] [blame] | 1598 | p = this_cpu_ptr(&bdp_ratelimits); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1599 | if (unlikely(current->nr_dirtied >= ratelimit)) |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1600 | *p = 0; |
Wu Fengguang | d3bc1fe | 2011-04-14 07:52:37 -0600 | [diff] [blame] | 1601 | else if (unlikely(*p >= ratelimit_pages)) { |
| 1602 | *p = 0; |
| 1603 | ratelimit = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1604 | } |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1605 | /* |
| 1606 | * Pick up the dirtied pages by the exited tasks. This avoids lots of |
| 1607 | * short-lived tasks (eg. gcc invocations in a kernel build) escaping |
| 1608 | * the dirty throttling and livelock other long-run dirtiers. |
| 1609 | */ |
Christoph Lameter | 7c8e018 | 2014-06-04 16:07:56 -0700 | [diff] [blame] | 1610 | p = this_cpu_ptr(&dirty_throttle_leaks); |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1611 | if (*p > 0 && current->nr_dirtied < ratelimit) { |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1612 | unsigned long nr_pages_dirtied; |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1613 | nr_pages_dirtied = min(*p, ratelimit - current->nr_dirtied); |
| 1614 | *p -= nr_pages_dirtied; |
| 1615 | current->nr_dirtied += nr_pages_dirtied; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1616 | } |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1617 | preempt_enable(); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1618 | |
| 1619 | if (unlikely(current->nr_dirtied >= ratelimit)) |
| 1620 | balance_dirty_pages(mapping, current->nr_dirtied); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1621 | } |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1622 | EXPORT_SYMBOL(balance_dirty_pages_ratelimited); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1623 | |
Andrew Morton | 232ea4d | 2007-02-28 20:13:21 -0800 | [diff] [blame] | 1624 | void throttle_vm_writeout(gfp_t gfp_mask) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1625 | { |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 1626 | unsigned long background_thresh; |
| 1627 | unsigned long dirty_thresh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1628 | |
| 1629 | for ( ; ; ) { |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1630 | global_dirty_limits(&background_thresh, &dirty_thresh); |
Fengguang Wu | 47a1333 | 2012-03-21 16:34:09 -0700 | [diff] [blame] | 1631 | dirty_thresh = hard_dirty_limit(dirty_thresh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1632 | |
| 1633 | /* |
| 1634 | * Boost the allowable dirty threshold a bit for page |
| 1635 | * allocators so they don't get DoS'ed by heavy writers |
| 1636 | */ |
| 1637 | dirty_thresh += dirty_thresh / 10; /* wheeee... */ |
| 1638 | |
Christoph Lameter | c24f21b | 2006-06-30 01:55:42 -0700 | [diff] [blame] | 1639 | if (global_page_state(NR_UNSTABLE_NFS) + |
| 1640 | global_page_state(NR_WRITEBACK) <= dirty_thresh) |
| 1641 | break; |
Jens Axboe | 8aa7e84 | 2009-07-09 14:52:32 +0200 | [diff] [blame] | 1642 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
Fengguang Wu | 369f238 | 2007-10-16 23:30:45 -0700 | [diff] [blame] | 1643 | |
| 1644 | /* |
| 1645 | * The caller might hold locks which can prevent IO completion |
| 1646 | * or progress in the filesystem. So we cannot just sit here |
| 1647 | * waiting for IO to complete. |
| 1648 | */ |
| 1649 | if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) |
| 1650 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1651 | } |
| 1652 | } |
| 1653 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1654 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1655 | * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs |
| 1656 | */ |
Joe Perches | cccad5b | 2014-06-06 14:38:09 -0700 | [diff] [blame] | 1657 | int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 1658 | void __user *buffer, size_t *length, loff_t *ppos) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1659 | { |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 1660 | proc_dointvec(table, write, buffer, length, ppos); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1661 | return 0; |
| 1662 | } |
| 1663 | |
Jens Axboe | c2c4986 | 2010-05-20 09:18:47 +0200 | [diff] [blame] | 1664 | #ifdef CONFIG_BLOCK |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1665 | void laptop_mode_timer_fn(unsigned long data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1666 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1667 | struct request_queue *q = (struct request_queue *)data; |
| 1668 | int nr_pages = global_page_state(NR_FILE_DIRTY) + |
| 1669 | global_page_state(NR_UNSTABLE_NFS); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1670 | |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1671 | /* |
| 1672 | * We want to write everything out, not just down to the dirty |
| 1673 | * threshold |
| 1674 | */ |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1675 | if (bdi_has_dirty_io(&q->backing_dev_info)) |
Curt Wohlgemuth | 0e175a1 | 2011-10-07 21:54:10 -0600 | [diff] [blame] | 1676 | bdi_start_writeback(&q->backing_dev_info, nr_pages, |
| 1677 | WB_REASON_LAPTOP_TIMER); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1678 | } |
| 1679 | |
| 1680 | /* |
| 1681 | * We've spun up the disk and we're in laptop mode: schedule writeback |
| 1682 | * of all dirty data a few seconds from now. If the flush is already scheduled |
| 1683 | * then push it back - the user is still using the disk. |
| 1684 | */ |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1685 | void laptop_io_completion(struct backing_dev_info *info) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1686 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1687 | mod_timer(&info->laptop_mode_wb_timer, jiffies + laptop_mode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1688 | } |
| 1689 | |
| 1690 | /* |
| 1691 | * We're in laptop mode and we've just synced. The sync's writes will have |
| 1692 | * caused another writeback to be scheduled by laptop_io_completion. |
| 1693 | * Nothing needs to be written back anymore, so we unschedule the writeback. |
| 1694 | */ |
| 1695 | void laptop_sync_completion(void) |
| 1696 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1697 | struct backing_dev_info *bdi; |
| 1698 | |
| 1699 | rcu_read_lock(); |
| 1700 | |
| 1701 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) |
| 1702 | del_timer(&bdi->laptop_mode_wb_timer); |
| 1703 | |
| 1704 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1705 | } |
Jens Axboe | c2c4986 | 2010-05-20 09:18:47 +0200 | [diff] [blame] | 1706 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1707 | |
| 1708 | /* |
| 1709 | * If ratelimit_pages is too high then we can get into dirty-data overload |
| 1710 | * if a large number of processes all perform writes at the same time. |
| 1711 | * If it is too low then SMP machines will call the (expensive) |
| 1712 | * get_writeback_state too often. |
| 1713 | * |
| 1714 | * Here we set ratelimit_pages to a level which ensures that when all CPUs are |
| 1715 | * 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] | 1716 | * thresholds. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1717 | */ |
| 1718 | |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 1719 | void writeback_set_ratelimit(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1720 | { |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1721 | unsigned long background_thresh; |
| 1722 | unsigned long dirty_thresh; |
| 1723 | global_dirty_limits(&background_thresh, &dirty_thresh); |
Fengguang Wu | 68809c7 | 2012-05-06 13:21:42 +0800 | [diff] [blame] | 1724 | global_dirty_limit = dirty_thresh; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1725 | ratelimit_pages = dirty_thresh / (num_online_cpus() * 32); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1726 | if (ratelimit_pages < 16) |
| 1727 | ratelimit_pages = 16; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1728 | } |
| 1729 | |
Paul Gortmaker | 0db0628 | 2013-06-19 14:53:51 -0400 | [diff] [blame] | 1730 | static int |
Srivatsa S. Bhat | 2f60d62 | 2012-09-28 20:27:49 +0800 | [diff] [blame] | 1731 | ratelimit_handler(struct notifier_block *self, unsigned long action, |
| 1732 | void *hcpu) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1733 | { |
Srivatsa S. Bhat | 2f60d62 | 2012-09-28 20:27:49 +0800 | [diff] [blame] | 1734 | |
| 1735 | switch (action & ~CPU_TASKS_FROZEN) { |
| 1736 | case CPU_ONLINE: |
| 1737 | case CPU_DEAD: |
| 1738 | writeback_set_ratelimit(); |
| 1739 | return NOTIFY_OK; |
| 1740 | default: |
| 1741 | return NOTIFY_DONE; |
| 1742 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1743 | } |
| 1744 | |
Paul Gortmaker | 0db0628 | 2013-06-19 14:53:51 -0400 | [diff] [blame] | 1745 | static struct notifier_block ratelimit_nb = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1746 | .notifier_call = ratelimit_handler, |
| 1747 | .next = NULL, |
| 1748 | }; |
| 1749 | |
| 1750 | /* |
Linus Torvalds | dc6e29d | 2007-01-29 16:37:38 -0800 | [diff] [blame] | 1751 | * Called early on to tune the page writeback dirty limits. |
| 1752 | * |
| 1753 | * We used to scale dirty pages according to how total memory |
| 1754 | * related to pages that could be allocated for buffers (by |
| 1755 | * comparing nr_free_buffer_pages() to vm_total_pages. |
| 1756 | * |
| 1757 | * However, that was when we used "dirty_ratio" to scale with |
| 1758 | * all memory, and we don't do that any more. "dirty_ratio" |
| 1759 | * is now applied to total non-HIGHPAGE memory (by subtracting |
| 1760 | * totalhigh_pages from vm_total_pages), and as such we can't |
| 1761 | * get into the old insane situation any more where we had |
| 1762 | * large amounts of dirty pages compared to a small amount of |
| 1763 | * non-HIGHMEM memory. |
| 1764 | * |
| 1765 | * But we might still want to scale the dirty_ratio by how |
| 1766 | * much memory the box has.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1767 | */ |
| 1768 | void __init page_writeback_init(void) |
| 1769 | { |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 1770 | writeback_set_ratelimit(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1771 | register_cpu_notifier(&ratelimit_nb); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1772 | |
Tejun Heo | 20ae007 | 2014-09-08 09:51:30 +0900 | [diff] [blame] | 1773 | fprop_global_init(&writeout_completions, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1774 | } |
| 1775 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1776 | /** |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1777 | * tag_pages_for_writeback - tag pages to be written by write_cache_pages |
| 1778 | * @mapping: address space structure to write |
| 1779 | * @start: starting page index |
| 1780 | * @end: ending page index (inclusive) |
| 1781 | * |
| 1782 | * This function scans the page range from @start to @end (inclusive) and tags |
| 1783 | * all pages that have DIRTY tag set with a special TOWRITE tag. The idea is |
| 1784 | * that write_cache_pages (or whoever calls this function) will then use |
| 1785 | * TOWRITE tag to identify pages eligible for writeback. This mechanism is |
| 1786 | * used to avoid livelocking of writeback by a process steadily creating new |
| 1787 | * dirty pages in the file (thus it is important for this function to be quick |
| 1788 | * so that it can tag pages faster than a dirtying process can create them). |
| 1789 | */ |
| 1790 | /* |
| 1791 | * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce tree_lock latency. |
| 1792 | */ |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1793 | void tag_pages_for_writeback(struct address_space *mapping, |
| 1794 | pgoff_t start, pgoff_t end) |
| 1795 | { |
Randy Dunlap | 3c111a0 | 2010-08-11 14:17:30 -0700 | [diff] [blame] | 1796 | #define WRITEBACK_TAG_BATCH 4096 |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1797 | unsigned long tagged; |
| 1798 | |
| 1799 | do { |
| 1800 | spin_lock_irq(&mapping->tree_lock); |
| 1801 | tagged = radix_tree_range_tag_if_tagged(&mapping->page_tree, |
| 1802 | &start, end, WRITEBACK_TAG_BATCH, |
| 1803 | PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE); |
| 1804 | spin_unlock_irq(&mapping->tree_lock); |
| 1805 | WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH); |
| 1806 | cond_resched(); |
Jan Kara | d5ed3a4 | 2010-08-19 14:13:33 -0700 | [diff] [blame] | 1807 | /* We check 'start' to handle wrapping when end == ~0UL */ |
| 1808 | } while (tagged >= WRITEBACK_TAG_BATCH && start); |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1809 | } |
| 1810 | EXPORT_SYMBOL(tag_pages_for_writeback); |
| 1811 | |
| 1812 | /** |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1813 | * 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] | 1814 | * @mapping: address space structure to write |
| 1815 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1816 | * @writepage: function called for each page |
| 1817 | * @data: data passed to writepage function |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1818 | * |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1819 | * 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] | 1820 | * if it's dirty. This is desirable behaviour for memory-cleaning writeback, |
| 1821 | * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() |
| 1822 | * and msync() need to guarantee that all the data which was dirty at the time |
| 1823 | * the call was made get new I/O started against them. If wbc->sync_mode is |
| 1824 | * WB_SYNC_ALL then we were called for data integrity and we must wait for |
| 1825 | * existing IO to complete. |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1826 | * |
| 1827 | * To avoid livelocks (when other process dirties new pages), we first tag |
| 1828 | * pages which should be written back with TOWRITE tag and only then start |
| 1829 | * writing them. For data-integrity sync we have to be careful so that we do |
| 1830 | * not miss some pages (e.g., because some other process has cleared TOWRITE |
| 1831 | * tag we set). The rule we follow is that TOWRITE tag can be cleared only |
| 1832 | * 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] | 1833 | */ |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1834 | int write_cache_pages(struct address_space *mapping, |
| 1835 | struct writeback_control *wbc, writepage_t writepage, |
| 1836 | void *data) |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1837 | { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1838 | int ret = 0; |
| 1839 | int done = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1840 | struct pagevec pvec; |
| 1841 | int nr_pages; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1842 | pgoff_t uninitialized_var(writeback_index); |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1843 | pgoff_t index; |
| 1844 | pgoff_t end; /* Inclusive */ |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1845 | pgoff_t done_index; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1846 | int cycled; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1847 | int range_whole = 0; |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1848 | int tag; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1849 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1850 | pagevec_init(&pvec, 0); |
| 1851 | if (wbc->range_cyclic) { |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1852 | writeback_index = mapping->writeback_index; /* prev offset */ |
| 1853 | index = writeback_index; |
| 1854 | if (index == 0) |
| 1855 | cycled = 1; |
| 1856 | else |
| 1857 | cycled = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1858 | end = -1; |
| 1859 | } else { |
| 1860 | index = wbc->range_start >> PAGE_CACHE_SHIFT; |
| 1861 | end = wbc->range_end >> PAGE_CACHE_SHIFT; |
| 1862 | if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) |
| 1863 | range_whole = 1; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1864 | cycled = 1; /* ignore range_cyclic tests */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1865 | } |
Wu Fengguang | 6e6938b | 2010-06-06 10:38:15 -0600 | [diff] [blame] | 1866 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1867 | tag = PAGECACHE_TAG_TOWRITE; |
| 1868 | else |
| 1869 | tag = PAGECACHE_TAG_DIRTY; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1870 | retry: |
Wu Fengguang | 6e6938b | 2010-06-06 10:38:15 -0600 | [diff] [blame] | 1871 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1872 | tag_pages_for_writeback(mapping, index, end); |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1873 | done_index = index; |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1874 | while (!done && (index <= end)) { |
| 1875 | int i; |
| 1876 | |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 1877 | nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag, |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1878 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1); |
| 1879 | if (nr_pages == 0) |
| 1880 | break; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1881 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1882 | for (i = 0; i < nr_pages; i++) { |
| 1883 | struct page *page = pvec.pages[i]; |
| 1884 | |
Nick Piggin | d5482cd | 2009-01-06 14:39:11 -0800 | [diff] [blame] | 1885 | /* |
| 1886 | * At this point, the page may be truncated or |
| 1887 | * invalidated (changing page->mapping to NULL), or |
| 1888 | * even swizzled back from swapper_space to tmpfs file |
| 1889 | * mapping. However, page->index will not change |
| 1890 | * because we have a reference on the page. |
| 1891 | */ |
| 1892 | if (page->index > end) { |
| 1893 | /* |
| 1894 | * can't be range_cyclic (1st pass) because |
| 1895 | * end == -1 in that case. |
| 1896 | */ |
| 1897 | done = 1; |
| 1898 | break; |
| 1899 | } |
| 1900 | |
Jun'ichi Nomura | cf15b07 | 2011-03-22 16:33:40 -0700 | [diff] [blame] | 1901 | done_index = page->index; |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1902 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1903 | lock_page(page); |
| 1904 | |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1905 | /* |
| 1906 | * Page truncated or invalidated. We can freely skip it |
| 1907 | * then, even for data integrity operations: the page |
| 1908 | * has disappeared concurrently, so there could be no |
| 1909 | * real expectation of this data interity operation |
| 1910 | * even if there is now a new, dirty page at the same |
| 1911 | * pagecache address. |
| 1912 | */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1913 | if (unlikely(page->mapping != mapping)) { |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1914 | continue_unlock: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1915 | unlock_page(page); |
| 1916 | continue; |
| 1917 | } |
| 1918 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 1919 | if (!PageDirty(page)) { |
| 1920 | /* someone wrote it for us */ |
| 1921 | goto continue_unlock; |
| 1922 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1923 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 1924 | if (PageWriteback(page)) { |
| 1925 | if (wbc->sync_mode != WB_SYNC_NONE) |
| 1926 | wait_on_page_writeback(page); |
| 1927 | else |
| 1928 | goto continue_unlock; |
| 1929 | } |
| 1930 | |
| 1931 | BUG_ON(PageWriteback(page)); |
| 1932 | if (!clear_page_dirty_for_io(page)) |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1933 | goto continue_unlock; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1934 | |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 1935 | trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1936 | ret = (*writepage)(page, wbc, data); |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1937 | if (unlikely(ret)) { |
| 1938 | if (ret == AOP_WRITEPAGE_ACTIVATE) { |
| 1939 | unlock_page(page); |
| 1940 | ret = 0; |
| 1941 | } else { |
| 1942 | /* |
| 1943 | * done_index is set past this page, |
| 1944 | * so media errors will not choke |
| 1945 | * background writeout for the entire |
| 1946 | * file. This has consequences for |
| 1947 | * range_cyclic semantics (ie. it may |
| 1948 | * not be suitable for data integrity |
| 1949 | * writeout). |
| 1950 | */ |
Jun'ichi Nomura | cf15b07 | 2011-03-22 16:33:40 -0700 | [diff] [blame] | 1951 | done_index = page->index + 1; |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1952 | done = 1; |
| 1953 | break; |
| 1954 | } |
Dave Chinner | 0b56492 | 2010-06-09 10:37:18 +1000 | [diff] [blame] | 1955 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1956 | |
Dave Chinner | 546a192 | 2010-08-24 11:44:34 +1000 | [diff] [blame] | 1957 | /* |
| 1958 | * We stop writing back only if we are not doing |
| 1959 | * integrity sync. In case of integrity sync we have to |
| 1960 | * keep going until we have written all the pages |
| 1961 | * we tagged for writeback prior to entering this loop. |
| 1962 | */ |
| 1963 | if (--wbc->nr_to_write <= 0 && |
| 1964 | wbc->sync_mode == WB_SYNC_NONE) { |
| 1965 | done = 1; |
| 1966 | break; |
Nick Piggin | 05fe478 | 2009-01-06 14:39:08 -0800 | [diff] [blame] | 1967 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1968 | } |
| 1969 | pagevec_release(&pvec); |
| 1970 | cond_resched(); |
| 1971 | } |
Nick Piggin | 3a4c680 | 2009-02-12 04:34:23 +0100 | [diff] [blame] | 1972 | if (!cycled && !done) { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1973 | /* |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1974 | * range_cyclic: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1975 | * We hit the last page and there is more work to be done: wrap |
| 1976 | * back to the start of the file |
| 1977 | */ |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1978 | cycled = 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1979 | index = 0; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1980 | end = writeback_index - 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1981 | goto retry; |
| 1982 | } |
Dave Chinner | 0b56492 | 2010-06-09 10:37:18 +1000 | [diff] [blame] | 1983 | if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) |
| 1984 | mapping->writeback_index = done_index; |
Aneesh Kumar K.V | 06d6cf6 | 2008-07-11 19:27:31 -0400 | [diff] [blame] | 1985 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1986 | return ret; |
| 1987 | } |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1988 | EXPORT_SYMBOL(write_cache_pages); |
| 1989 | |
| 1990 | /* |
| 1991 | * Function used by generic_writepages to call the real writepage |
| 1992 | * function and set the mapping flags on error |
| 1993 | */ |
| 1994 | static int __writepage(struct page *page, struct writeback_control *wbc, |
| 1995 | void *data) |
| 1996 | { |
| 1997 | struct address_space *mapping = data; |
| 1998 | int ret = mapping->a_ops->writepage(page, wbc); |
| 1999 | mapping_set_error(mapping, ret); |
| 2000 | return ret; |
| 2001 | } |
| 2002 | |
| 2003 | /** |
| 2004 | * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them. |
| 2005 | * @mapping: address space structure to write |
| 2006 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
| 2007 | * |
| 2008 | * This is a library function, which implements the writepages() |
| 2009 | * address_space_operation. |
| 2010 | */ |
| 2011 | int generic_writepages(struct address_space *mapping, |
| 2012 | struct writeback_control *wbc) |
| 2013 | { |
Shaohua Li | 9b6096a | 2011-03-17 10:47:06 +0100 | [diff] [blame] | 2014 | struct blk_plug plug; |
| 2015 | int ret; |
| 2016 | |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2017 | /* deal with chardevs and other special file */ |
| 2018 | if (!mapping->a_ops->writepage) |
| 2019 | return 0; |
| 2020 | |
Shaohua Li | 9b6096a | 2011-03-17 10:47:06 +0100 | [diff] [blame] | 2021 | blk_start_plug(&plug); |
| 2022 | ret = write_cache_pages(mapping, wbc, __writepage, mapping); |
| 2023 | blk_finish_plug(&plug); |
| 2024 | return ret; |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2025 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2026 | |
| 2027 | EXPORT_SYMBOL(generic_writepages); |
| 2028 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2029 | int do_writepages(struct address_space *mapping, struct writeback_control *wbc) |
| 2030 | { |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 2031 | int ret; |
| 2032 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2033 | if (wbc->nr_to_write <= 0) |
| 2034 | return 0; |
| 2035 | if (mapping->a_ops->writepages) |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 2036 | ret = mapping->a_ops->writepages(mapping, wbc); |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 2037 | else |
| 2038 | ret = generic_writepages(mapping, wbc); |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 2039 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2040 | } |
| 2041 | |
| 2042 | /** |
| 2043 | * 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] | 2044 | * @page: the page to write |
| 2045 | * @wait: if true, wait on writeout |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2046 | * |
| 2047 | * The page must be locked by the caller and will be unlocked upon return. |
| 2048 | * |
| 2049 | * write_one_page() returns a negative error code if I/O failed. |
| 2050 | */ |
| 2051 | int write_one_page(struct page *page, int wait) |
| 2052 | { |
| 2053 | struct address_space *mapping = page->mapping; |
| 2054 | int ret = 0; |
| 2055 | struct writeback_control wbc = { |
| 2056 | .sync_mode = WB_SYNC_ALL, |
| 2057 | .nr_to_write = 1, |
| 2058 | }; |
| 2059 | |
| 2060 | BUG_ON(!PageLocked(page)); |
| 2061 | |
| 2062 | if (wait) |
| 2063 | wait_on_page_writeback(page); |
| 2064 | |
| 2065 | if (clear_page_dirty_for_io(page)) { |
| 2066 | page_cache_get(page); |
| 2067 | ret = mapping->a_ops->writepage(page, &wbc); |
| 2068 | if (ret == 0 && wait) { |
| 2069 | wait_on_page_writeback(page); |
| 2070 | if (PageError(page)) |
| 2071 | ret = -EIO; |
| 2072 | } |
| 2073 | page_cache_release(page); |
| 2074 | } else { |
| 2075 | unlock_page(page); |
| 2076 | } |
| 2077 | return ret; |
| 2078 | } |
| 2079 | EXPORT_SYMBOL(write_one_page); |
| 2080 | |
| 2081 | /* |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 2082 | * For address_spaces which do not use buffers nor write back. |
| 2083 | */ |
| 2084 | int __set_page_dirty_no_writeback(struct page *page) |
| 2085 | { |
| 2086 | if (!PageDirty(page)) |
Bob Liu | c3f0da6 | 2011-01-13 15:45:49 -0800 | [diff] [blame] | 2087 | return !TestSetPageDirty(page); |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 2088 | return 0; |
| 2089 | } |
| 2090 | |
| 2091 | /* |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2092 | * Helper function for set_page_dirty family. |
| 2093 | * NOTE: This relies on being atomic wrt interrupts. |
| 2094 | */ |
| 2095 | void account_page_dirtied(struct page *page, struct address_space *mapping) |
| 2096 | { |
Tejun Heo | 9fb0a7d | 2013-01-11 13:06:37 -0800 | [diff] [blame] | 2097 | trace_writeback_dirty_page(page, mapping); |
| 2098 | |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2099 | if (mapping_cap_account_dirty(mapping)) { |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2100 | struct backing_dev_info *bdi = inode_to_bdi(mapping->host); |
| 2101 | |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2102 | __inc_zone_page_state(page, NR_FILE_DIRTY); |
Michael Rubin | ea941f0 | 2010-10-26 14:21:35 -0700 | [diff] [blame] | 2103 | __inc_zone_page_state(page, NR_DIRTIED); |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2104 | __inc_bdi_stat(bdi, BDI_RECLAIMABLE); |
| 2105 | __inc_bdi_stat(bdi, BDI_DIRTIED); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2106 | task_io_account_write(PAGE_CACHE_SIZE); |
Wu Fengguang | d3bc1fe | 2011-04-14 07:52:37 -0600 | [diff] [blame] | 2107 | current->nr_dirtied++; |
| 2108 | this_cpu_inc(bdp_ratelimits); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2109 | } |
| 2110 | } |
Michael Rubin | 679ceac | 2010-08-20 02:31:26 -0700 | [diff] [blame] | 2111 | EXPORT_SYMBOL(account_page_dirtied); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2112 | |
| 2113 | /* |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2114 | * Helper function for deaccounting dirty page without writeback. |
| 2115 | * |
| 2116 | * Doing this should *normally* only ever be done when a page |
| 2117 | * is truncated, and is not actually mapped anywhere at all. However, |
| 2118 | * fs/buffer.c does this when it notices that somebody has cleaned |
| 2119 | * out all the buffers on a page without actually doing it through |
| 2120 | * the VM. Can you say "ext3 is horribly ugly"? Thought you could. |
| 2121 | */ |
| 2122 | void account_page_cleaned(struct page *page, struct address_space *mapping) |
| 2123 | { |
| 2124 | if (mapping_cap_account_dirty(mapping)) { |
| 2125 | dec_zone_page_state(page, NR_FILE_DIRTY); |
| 2126 | dec_bdi_stat(inode_to_bdi(mapping->host), BDI_RECLAIMABLE); |
| 2127 | task_io_account_cancelled_write(PAGE_CACHE_SIZE); |
| 2128 | } |
| 2129 | } |
| 2130 | EXPORT_SYMBOL(account_page_cleaned); |
| 2131 | |
| 2132 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2133 | * For address_spaces which do not use buffers. Just tag the page as dirty in |
| 2134 | * its radix tree. |
| 2135 | * |
| 2136 | * This is also used when a single buffer is being dirtied: we want to set the |
| 2137 | * page dirty in that case, but not all the buffers. This is a "bottom-up" |
| 2138 | * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying. |
| 2139 | * |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2140 | * The caller must ensure this doesn't race with truncation. Most will simply |
| 2141 | * hold the page lock, but e.g. zap_pte_range() calls with the page mapped and |
| 2142 | * the pte lock held, which also locks out truncation. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2143 | */ |
| 2144 | int __set_page_dirty_nobuffers(struct page *page) |
| 2145 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2146 | if (!TestSetPageDirty(page)) { |
| 2147 | struct address_space *mapping = page_mapping(page); |
KOSAKI Motohiro | a85d9df | 2014-02-06 12:04:24 -0800 | [diff] [blame] | 2148 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2149 | |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2150 | if (!mapping) |
| 2151 | return 1; |
| 2152 | |
KOSAKI Motohiro | a85d9df | 2014-02-06 12:04:24 -0800 | [diff] [blame] | 2153 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2154 | BUG_ON(page_mapping(page) != mapping); |
| 2155 | WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page)); |
| 2156 | account_page_dirtied(page, mapping); |
| 2157 | radix_tree_tag_set(&mapping->page_tree, page_index(page), |
| 2158 | PAGECACHE_TAG_DIRTY); |
KOSAKI Motohiro | a85d9df | 2014-02-06 12:04:24 -0800 | [diff] [blame] | 2159 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2160 | if (mapping->host) { |
| 2161 | /* !PageAnon && !swapper_space */ |
| 2162 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2163 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2164 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2165 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2166 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2167 | } |
| 2168 | EXPORT_SYMBOL(__set_page_dirty_nobuffers); |
| 2169 | |
| 2170 | /* |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2171 | * Call this whenever redirtying a page, to de-account the dirty counters |
| 2172 | * (NR_DIRTIED, BDI_DIRTIED, tsk->nr_dirtied), so that they match the written |
| 2173 | * counters (NR_WRITTEN, BDI_WRITTEN) in long term. The mismatches will lead to |
| 2174 | * systematic errors in balanced_dirty_ratelimit and the dirty pages position |
| 2175 | * control. |
| 2176 | */ |
| 2177 | void account_page_redirty(struct page *page) |
| 2178 | { |
| 2179 | struct address_space *mapping = page->mapping; |
| 2180 | if (mapping && mapping_cap_account_dirty(mapping)) { |
| 2181 | current->nr_dirtied--; |
| 2182 | dec_zone_page_state(page, NR_DIRTIED); |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2183 | dec_bdi_stat(inode_to_bdi(mapping->host), BDI_DIRTIED); |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2184 | } |
| 2185 | } |
| 2186 | EXPORT_SYMBOL(account_page_redirty); |
| 2187 | |
| 2188 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2189 | * When a writepage implementation decides that it doesn't want to write this |
| 2190 | * page for some reason, it should redirty the locked page via |
| 2191 | * redirty_page_for_writepage() and it should then unlock the page and return 0 |
| 2192 | */ |
| 2193 | int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page) |
| 2194 | { |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2195 | int ret; |
| 2196 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2197 | wbc->pages_skipped++; |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2198 | ret = __set_page_dirty_nobuffers(page); |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2199 | account_page_redirty(page); |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2200 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2201 | } |
| 2202 | EXPORT_SYMBOL(redirty_page_for_writepage); |
| 2203 | |
| 2204 | /* |
Wu Fengguang | 6746aff | 2009-09-16 11:50:14 +0200 | [diff] [blame] | 2205 | * Dirty a page. |
| 2206 | * |
| 2207 | * For pages with a mapping this should be done under the page lock |
| 2208 | * for the benefit of asynchronous memory errors who prefer a consistent |
| 2209 | * dirty state. This rule can be broken in some special cases, |
| 2210 | * but should be better not to. |
| 2211 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2212 | * If the mapping doesn't provide a set_page_dirty a_op, then |
| 2213 | * just fall through and assume that it wants buffer_heads. |
| 2214 | */ |
Nick Piggin | 1cf6e7d | 2009-02-18 14:48:18 -0800 | [diff] [blame] | 2215 | int set_page_dirty(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2216 | { |
| 2217 | struct address_space *mapping = page_mapping(page); |
| 2218 | |
| 2219 | if (likely(mapping)) { |
| 2220 | int (*spd)(struct page *) = mapping->a_ops->set_page_dirty; |
Minchan Kim | 278df9f | 2011-03-22 16:32:54 -0700 | [diff] [blame] | 2221 | /* |
| 2222 | * readahead/lru_deactivate_page could remain |
| 2223 | * PG_readahead/PG_reclaim due to race with end_page_writeback |
| 2224 | * About readahead, if the page is written, the flags would be |
| 2225 | * reset. So no problem. |
| 2226 | * About lru_deactivate_page, if the page is redirty, the flag |
| 2227 | * will be reset. So no problem. but if the page is used by readahead |
| 2228 | * it will confuse readahead and make it restart the size rampup |
| 2229 | * process. But it's a trivial problem. |
| 2230 | */ |
Naoya Horiguchi | a4bb3ec | 2015-04-15 16:13:17 -0700 | [diff] [blame] | 2231 | if (PageReclaim(page)) |
| 2232 | ClearPageReclaim(page); |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 2233 | #ifdef CONFIG_BLOCK |
| 2234 | if (!spd) |
| 2235 | spd = __set_page_dirty_buffers; |
| 2236 | #endif |
| 2237 | return (*spd)(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2238 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2239 | if (!PageDirty(page)) { |
| 2240 | if (!TestSetPageDirty(page)) |
| 2241 | return 1; |
| 2242 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2243 | return 0; |
| 2244 | } |
| 2245 | EXPORT_SYMBOL(set_page_dirty); |
| 2246 | |
| 2247 | /* |
| 2248 | * set_page_dirty() is racy if the caller has no reference against |
| 2249 | * page->mapping->host, and if the page is unlocked. This is because another |
| 2250 | * CPU could truncate the page off the mapping and then free the mapping. |
| 2251 | * |
| 2252 | * Usually, the page _is_ locked, or the caller is a user-space process which |
| 2253 | * holds a reference on the inode by having an open file. |
| 2254 | * |
| 2255 | * In other cases, the page should be locked before running set_page_dirty(). |
| 2256 | */ |
| 2257 | int set_page_dirty_lock(struct page *page) |
| 2258 | { |
| 2259 | int ret; |
| 2260 | |
Jens Axboe | 7eaceac | 2011-03-10 08:52:07 +0100 | [diff] [blame] | 2261 | lock_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2262 | ret = set_page_dirty(page); |
| 2263 | unlock_page(page); |
| 2264 | return ret; |
| 2265 | } |
| 2266 | EXPORT_SYMBOL(set_page_dirty_lock); |
| 2267 | |
| 2268 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2269 | * Clear a page's dirty flag, while caring for dirty memory accounting. |
| 2270 | * Returns true if the page was previously dirty. |
| 2271 | * |
| 2272 | * This is for preparing to put the page under writeout. We leave the page |
| 2273 | * tagged as dirty in the radix tree so that a concurrent write-for-sync |
| 2274 | * can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage |
| 2275 | * implementation will run either set_page_writeback() or set_page_dirty(), |
| 2276 | * at which stage we bring the page's dirty flag and radix-tree dirty tag |
| 2277 | * back into sync. |
| 2278 | * |
| 2279 | * This incoherency between the page's dirty flag and radix-tree tag is |
| 2280 | * unfortunate, but it only exists while the page is locked. |
| 2281 | */ |
| 2282 | int clear_page_dirty_for_io(struct page *page) |
| 2283 | { |
| 2284 | struct address_space *mapping = page_mapping(page); |
| 2285 | |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2286 | BUG_ON(!PageLocked(page)); |
| 2287 | |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2288 | if (mapping && mapping_cap_account_dirty(mapping)) { |
| 2289 | /* |
| 2290 | * Yes, Virginia, this is indeed insane. |
| 2291 | * |
| 2292 | * We use this sequence to make sure that |
| 2293 | * (a) we account for dirty stats properly |
| 2294 | * (b) we tell the low-level filesystem to |
| 2295 | * mark the whole page dirty if it was |
| 2296 | * dirty in a pagetable. Only to then |
| 2297 | * (c) clean the page again and return 1 to |
| 2298 | * cause the writeback. |
| 2299 | * |
| 2300 | * This way we avoid all nasty races with the |
| 2301 | * dirty bit in multiple places and clearing |
| 2302 | * them concurrently from different threads. |
| 2303 | * |
| 2304 | * Note! Normally the "set_page_dirty(page)" |
| 2305 | * has no effect on the actual dirty bit - since |
| 2306 | * that will already usually be set. But we |
| 2307 | * need the side effects, and it can help us |
| 2308 | * avoid races. |
| 2309 | * |
| 2310 | * We basically use the page "master dirty bit" |
| 2311 | * as a serialization point for all the different |
| 2312 | * threads doing their things. |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2313 | */ |
| 2314 | if (page_mkclean(page)) |
| 2315 | set_page_dirty(page); |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2316 | /* |
| 2317 | * We carefully synchronise fault handlers against |
| 2318 | * installing a dirty pte and marking the page dirty |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2319 | * at this point. We do this by having them hold the |
| 2320 | * page lock while dirtying the page, and pages are |
| 2321 | * always locked coming in here, so we get the desired |
| 2322 | * exclusion. |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2323 | */ |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2324 | if (TestClearPageDirty(page)) { |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2325 | dec_zone_page_state(page, NR_FILE_DIRTY); |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2326 | dec_bdi_stat(inode_to_bdi(mapping->host), |
Peter Zijlstra | c9e51e4 | 2007-10-16 23:25:47 -0700 | [diff] [blame] | 2327 | BDI_RECLAIMABLE); |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2328 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2329 | } |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2330 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2331 | } |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2332 | return TestClearPageDirty(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2333 | } |
Hans Reiser | 58bb01a | 2005-11-18 01:10:53 -0800 | [diff] [blame] | 2334 | EXPORT_SYMBOL(clear_page_dirty_for_io); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2335 | |
| 2336 | int test_clear_page_writeback(struct page *page) |
| 2337 | { |
| 2338 | struct address_space *mapping = page_mapping(page); |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2339 | struct mem_cgroup *memcg; |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2340 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2341 | |
Johannes Weiner | 6de2261 | 2015-02-11 15:25:01 -0800 | [diff] [blame] | 2342 | memcg = mem_cgroup_begin_page_stat(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2343 | if (mapping) { |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2344 | struct backing_dev_info *bdi = inode_to_bdi(mapping->host); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2345 | unsigned long flags; |
| 2346 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2347 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2348 | ret = TestClearPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2349 | if (ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2350 | radix_tree_tag_clear(&mapping->page_tree, |
| 2351 | page_index(page), |
| 2352 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 2353 | if (bdi_cap_account_writeback(bdi)) { |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2354 | __dec_bdi_stat(bdi, BDI_WRITEBACK); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 2355 | __bdi_writeout_inc(bdi); |
| 2356 | } |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2357 | } |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2358 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2359 | } else { |
| 2360 | ret = TestClearPageWriteback(page); |
| 2361 | } |
Wu Fengguang | 99b12e3 | 2011-07-25 17:12:37 -0700 | [diff] [blame] | 2362 | if (ret) { |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2363 | mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_WRITEBACK); |
Andrew Morton | d688abf | 2007-07-19 01:49:17 -0700 | [diff] [blame] | 2364 | dec_zone_page_state(page, NR_WRITEBACK); |
Wu Fengguang | 99b12e3 | 2011-07-25 17:12:37 -0700 | [diff] [blame] | 2365 | inc_zone_page_state(page, NR_WRITTEN); |
| 2366 | } |
Johannes Weiner | 6de2261 | 2015-02-11 15:25:01 -0800 | [diff] [blame] | 2367 | mem_cgroup_end_page_stat(memcg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2368 | return ret; |
| 2369 | } |
| 2370 | |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2371 | int __test_set_page_writeback(struct page *page, bool keep_write) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2372 | { |
| 2373 | struct address_space *mapping = page_mapping(page); |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2374 | struct mem_cgroup *memcg; |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2375 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2376 | |
Johannes Weiner | 6de2261 | 2015-02-11 15:25:01 -0800 | [diff] [blame] | 2377 | memcg = mem_cgroup_begin_page_stat(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2378 | if (mapping) { |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2379 | struct backing_dev_info *bdi = inode_to_bdi(mapping->host); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2380 | unsigned long flags; |
| 2381 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2382 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2383 | ret = TestSetPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2384 | if (!ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2385 | radix_tree_tag_set(&mapping->page_tree, |
| 2386 | page_index(page), |
| 2387 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 2388 | if (bdi_cap_account_writeback(bdi)) |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2389 | __inc_bdi_stat(bdi, BDI_WRITEBACK); |
| 2390 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2391 | if (!PageDirty(page)) |
| 2392 | radix_tree_tag_clear(&mapping->page_tree, |
| 2393 | page_index(page), |
| 2394 | PAGECACHE_TAG_DIRTY); |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2395 | if (!keep_write) |
| 2396 | radix_tree_tag_clear(&mapping->page_tree, |
| 2397 | page_index(page), |
| 2398 | PAGECACHE_TAG_TOWRITE); |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2399 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2400 | } else { |
| 2401 | ret = TestSetPageWriteback(page); |
| 2402 | } |
Johannes Weiner | 3a3c02e | 2014-10-29 14:50:46 -0700 | [diff] [blame] | 2403 | if (!ret) { |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2404 | mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_WRITEBACK); |
Johannes Weiner | 3a3c02e | 2014-10-29 14:50:46 -0700 | [diff] [blame] | 2405 | inc_zone_page_state(page, NR_WRITEBACK); |
| 2406 | } |
Johannes Weiner | 6de2261 | 2015-02-11 15:25:01 -0800 | [diff] [blame] | 2407 | mem_cgroup_end_page_stat(memcg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2408 | return ret; |
| 2409 | |
| 2410 | } |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2411 | EXPORT_SYMBOL(__test_set_page_writeback); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2412 | |
| 2413 | /* |
Nick Piggin | 0012818 | 2007-10-16 01:24:40 -0700 | [diff] [blame] | 2414 | * 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] | 2415 | * passed tag. |
| 2416 | */ |
| 2417 | int mapping_tagged(struct address_space *mapping, int tag) |
| 2418 | { |
Konstantin Khlebnikov | 72c4783 | 2011-07-25 17:12:31 -0700 | [diff] [blame] | 2419 | return radix_tree_tagged(&mapping->page_tree, tag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2420 | } |
| 2421 | EXPORT_SYMBOL(mapping_tagged); |
Darrick J. Wong | 1d1d1a7 | 2013-02-21 16:42:51 -0800 | [diff] [blame] | 2422 | |
| 2423 | /** |
| 2424 | * wait_for_stable_page() - wait for writeback to finish, if necessary. |
| 2425 | * @page: The page to wait on. |
| 2426 | * |
| 2427 | * This function determines if the given page is related to a backing device |
| 2428 | * that requires page contents to be held stable during writeback. If so, then |
| 2429 | * it will wait for any pending writeback to complete. |
| 2430 | */ |
| 2431 | void wait_for_stable_page(struct page *page) |
| 2432 | { |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2433 | if (bdi_cap_stable_pages_required(inode_to_bdi(page->mapping->host))) |
| 2434 | wait_on_page_writeback(page); |
Darrick J. Wong | 1d1d1a7 | 2013-02-21 16:42:51 -0800 | [diff] [blame] | 2435 | } |
| 2436 | EXPORT_SYMBOL_GPL(wait_for_stable_page); |