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 | 90eec10 | 2015-11-16 11:08:45 +0100 | [diff] [blame] | 5 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra |
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 | |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 125 | struct wb_domain global_wb_domain; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 126 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 127 | /* consolidated parameters for balance_dirty_pages() and its subroutines */ |
| 128 | struct dirty_throttle_control { |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 129 | #ifdef CONFIG_CGROUP_WRITEBACK |
| 130 | struct wb_domain *dom; |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 131 | struct dirty_throttle_control *gdtc; /* only set in memcg dtc's */ |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 132 | #endif |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 133 | struct bdi_writeback *wb; |
Tejun Heo | e9770b3 | 2015-05-22 18:23:27 -0400 | [diff] [blame] | 134 | struct fprop_local_percpu *wb_completions; |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 135 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 136 | unsigned long avail; /* dirtyable */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 137 | unsigned long dirty; /* file_dirty + write + nfs */ |
| 138 | unsigned long thresh; /* dirty threshold */ |
| 139 | unsigned long bg_thresh; /* dirty background threshold */ |
| 140 | |
| 141 | unsigned long wb_dirty; /* per-wb counterparts */ |
| 142 | unsigned long wb_thresh; |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 143 | unsigned long wb_bg_thresh; |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 144 | |
| 145 | unsigned long pos_ratio; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 146 | }; |
| 147 | |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 148 | /* |
| 149 | * Length of period for aging writeout fractions of bdis. This is an |
| 150 | * arbitrarily chosen number. The longer the period, the slower fractions will |
| 151 | * reflect changes in current writeout rate. |
| 152 | */ |
| 153 | #define VM_COMPLETIONS_PERIOD_LEN (3*HZ) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 154 | |
Tejun Heo | 693108a | 2015-05-22 17:13:49 -0400 | [diff] [blame] | 155 | #ifdef CONFIG_CGROUP_WRITEBACK |
| 156 | |
Tejun Heo | d60d1bd | 2015-09-29 12:47:53 -0400 | [diff] [blame] | 157 | #define GDTC_INIT(__wb) .wb = (__wb), \ |
| 158 | .dom = &global_wb_domain, \ |
| 159 | .wb_completions = &(__wb)->completions |
| 160 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 161 | #define GDTC_INIT_NO_WB .dom = &global_wb_domain |
Tejun Heo | d60d1bd | 2015-09-29 12:47:53 -0400 | [diff] [blame] | 162 | |
| 163 | #define MDTC_INIT(__wb, __gdtc) .wb = (__wb), \ |
| 164 | .dom = mem_cgroup_wb_domain(__wb), \ |
| 165 | .wb_completions = &(__wb)->memcg_completions, \ |
| 166 | .gdtc = __gdtc |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 167 | |
| 168 | static bool mdtc_valid(struct dirty_throttle_control *dtc) |
| 169 | { |
| 170 | return dtc->dom; |
| 171 | } |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 172 | |
| 173 | static struct wb_domain *dtc_dom(struct dirty_throttle_control *dtc) |
| 174 | { |
| 175 | return dtc->dom; |
| 176 | } |
| 177 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 178 | static struct dirty_throttle_control *mdtc_gdtc(struct dirty_throttle_control *mdtc) |
| 179 | { |
| 180 | return mdtc->gdtc; |
| 181 | } |
| 182 | |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 183 | static struct fprop_local_percpu *wb_memcg_completions(struct bdi_writeback *wb) |
| 184 | { |
| 185 | return &wb->memcg_completions; |
| 186 | } |
| 187 | |
Tejun Heo | 693108a | 2015-05-22 17:13:49 -0400 | [diff] [blame] | 188 | static void wb_min_max_ratio(struct bdi_writeback *wb, |
| 189 | unsigned long *minp, unsigned long *maxp) |
| 190 | { |
| 191 | unsigned long this_bw = wb->avg_write_bandwidth; |
| 192 | unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); |
| 193 | unsigned long long min = wb->bdi->min_ratio; |
| 194 | unsigned long long max = wb->bdi->max_ratio; |
| 195 | |
| 196 | /* |
| 197 | * @wb may already be clean by the time control reaches here and |
| 198 | * the total may not include its bw. |
| 199 | */ |
| 200 | if (this_bw < tot_bw) { |
| 201 | if (min) { |
| 202 | min *= this_bw; |
| 203 | do_div(min, tot_bw); |
| 204 | } |
| 205 | if (max < 100) { |
| 206 | max *= this_bw; |
| 207 | do_div(max, tot_bw); |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | *minp = min; |
| 212 | *maxp = max; |
| 213 | } |
| 214 | |
| 215 | #else /* CONFIG_CGROUP_WRITEBACK */ |
| 216 | |
Tejun Heo | d60d1bd | 2015-09-29 12:47:53 -0400 | [diff] [blame] | 217 | #define GDTC_INIT(__wb) .wb = (__wb), \ |
| 218 | .wb_completions = &(__wb)->completions |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 219 | #define GDTC_INIT_NO_WB |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 220 | #define MDTC_INIT(__wb, __gdtc) |
| 221 | |
| 222 | static bool mdtc_valid(struct dirty_throttle_control *dtc) |
| 223 | { |
| 224 | return false; |
| 225 | } |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 226 | |
| 227 | static struct wb_domain *dtc_dom(struct dirty_throttle_control *dtc) |
| 228 | { |
| 229 | return &global_wb_domain; |
| 230 | } |
| 231 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 232 | static struct dirty_throttle_control *mdtc_gdtc(struct dirty_throttle_control *mdtc) |
| 233 | { |
| 234 | return NULL; |
| 235 | } |
| 236 | |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 237 | static struct fprop_local_percpu *wb_memcg_completions(struct bdi_writeback *wb) |
| 238 | { |
| 239 | return NULL; |
| 240 | } |
| 241 | |
Tejun Heo | 693108a | 2015-05-22 17:13:49 -0400 | [diff] [blame] | 242 | static void wb_min_max_ratio(struct bdi_writeback *wb, |
| 243 | unsigned long *minp, unsigned long *maxp) |
| 244 | { |
| 245 | *minp = wb->bdi->min_ratio; |
| 246 | *maxp = wb->bdi->max_ratio; |
| 247 | } |
| 248 | |
| 249 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
| 250 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 251 | /* |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 252 | * In a memory zone, there is a certain amount of pages we consider |
| 253 | * available for the page cache, which is essentially the number of |
| 254 | * free and reclaimable pages, minus some zone reserves to protect |
| 255 | * lowmem and the ability to uphold the zone's watermarks without |
| 256 | * requiring writeback. |
| 257 | * |
| 258 | * This number of dirtyable pages is the base value of which the |
| 259 | * user-configurable dirty ratio is the effictive number of pages that |
| 260 | * are allowed to be actually dirtied. Per individual zone, or |
| 261 | * globally by using the sum of dirtyable pages over all zones. |
| 262 | * |
| 263 | * Because the user is allowed to specify the dirty limit globally as |
| 264 | * absolute number of bytes, calculating the per-zone dirty limit can |
| 265 | * require translating the configured limit into a percentage of |
| 266 | * global dirtyable memory first. |
| 267 | */ |
| 268 | |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 269 | /** |
| 270 | * zone_dirtyable_memory - number of dirtyable pages in a zone |
| 271 | * @zone: the zone |
| 272 | * |
| 273 | * Returns the zone's number of pages potentially available for dirty |
| 274 | * page cache. This is the base value for the per-zone dirty limits. |
| 275 | */ |
| 276 | static unsigned long zone_dirtyable_memory(struct zone *zone) |
| 277 | { |
| 278 | unsigned long nr_pages; |
| 279 | |
| 280 | nr_pages = zone_page_state(zone, NR_FREE_PAGES); |
Johannes Weiner | a8d0143 | 2016-01-14 15:20:15 -0800 | [diff] [blame] | 281 | /* |
| 282 | * Pages reserved for the kernel should not be considered |
| 283 | * dirtyable, to prevent a situation where reclaim has to |
| 284 | * clean pages in order to balance the zones. |
| 285 | */ |
| 286 | nr_pages -= min(nr_pages, zone->totalreserve_pages); |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 287 | |
Johannes Weiner | a1c3bfb | 2014-01-29 14:05:41 -0800 | [diff] [blame] | 288 | nr_pages += zone_page_state(zone, NR_INACTIVE_FILE); |
| 289 | nr_pages += zone_page_state(zone, NR_ACTIVE_FILE); |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 290 | |
| 291 | return nr_pages; |
| 292 | } |
| 293 | |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 294 | static unsigned long highmem_dirtyable_memory(unsigned long total) |
| 295 | { |
| 296 | #ifdef CONFIG_HIGHMEM |
| 297 | int node; |
| 298 | unsigned long x = 0; |
| 299 | |
| 300 | for_each_node_state(node, N_HIGH_MEMORY) { |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 301 | struct zone *z = &NODE_DATA(node)->node_zones[ZONE_HIGHMEM]; |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 302 | |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 303 | x += zone_dirtyable_memory(z); |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 304 | } |
| 305 | /* |
Sonny Rao | c8b74c2f | 2012-12-20 15:05:07 -0800 | [diff] [blame] | 306 | * Unreclaimable memory (kernel memory or anonymous memory |
| 307 | * without swap) can bring down the dirtyable pages below |
| 308 | * the zone's dirty balance reserve and the above calculation |
| 309 | * will underflow. However we still want to add in nodes |
| 310 | * which are below threshold (negative values) to get a more |
| 311 | * accurate calculation but make sure that the total never |
| 312 | * underflows. |
| 313 | */ |
| 314 | if ((long)x < 0) |
| 315 | x = 0; |
| 316 | |
| 317 | /* |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 318 | * Make sure that the number of highmem pages is never larger |
| 319 | * than the number of the total dirtyable memory. This can only |
| 320 | * occur in very strange VM situations but we want to make sure |
| 321 | * that this does not occur. |
| 322 | */ |
| 323 | return min(x, total); |
| 324 | #else |
| 325 | return 0; |
| 326 | #endif |
| 327 | } |
| 328 | |
| 329 | /** |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 330 | * global_dirtyable_memory - number of globally dirtyable pages |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 331 | * |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 332 | * Returns the global number of pages potentially available for dirty |
| 333 | * page cache. This is the base value for the global dirty limits. |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 334 | */ |
H Hartley Sweeten | 18cf8cf | 2012-04-12 13:44:20 -0700 | [diff] [blame] | 335 | static unsigned long global_dirtyable_memory(void) |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 336 | { |
| 337 | unsigned long x; |
| 338 | |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 339 | x = global_page_state(NR_FREE_PAGES); |
Johannes Weiner | a8d0143 | 2016-01-14 15:20:15 -0800 | [diff] [blame] | 340 | /* |
| 341 | * Pages reserved for the kernel should not be considered |
| 342 | * dirtyable, to prevent a situation where reclaim has to |
| 343 | * clean pages in order to balance the zones. |
| 344 | */ |
| 345 | x -= min(x, totalreserve_pages); |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 346 | |
Johannes Weiner | a1c3bfb | 2014-01-29 14:05:41 -0800 | [diff] [blame] | 347 | x += global_page_state(NR_INACTIVE_FILE); |
| 348 | x += global_page_state(NR_ACTIVE_FILE); |
Johannes Weiner | a804552 | 2014-01-29 14:05:39 -0800 | [diff] [blame] | 349 | |
Johannes Weiner | 1edf223 | 2012-01-10 15:06:57 -0800 | [diff] [blame] | 350 | if (!vm_highmem_is_dirtyable) |
| 351 | x -= highmem_dirtyable_memory(x); |
| 352 | |
| 353 | return x + 1; /* Ensure that we never return 0 */ |
| 354 | } |
| 355 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 356 | /** |
| 357 | * domain_dirty_limits - calculate thresh and bg_thresh for a wb_domain |
| 358 | * @dtc: dirty_throttle_control of interest |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 359 | * |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 360 | * Calculate @dtc->thresh and ->bg_thresh considering |
| 361 | * vm_dirty_{bytes|ratio} and dirty_background_{bytes|ratio}. The caller |
| 362 | * must ensure that @dtc->avail is set before calling this function. The |
| 363 | * dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 364 | * real-time tasks. |
| 365 | */ |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 366 | static void domain_dirty_limits(struct dirty_throttle_control *dtc) |
| 367 | { |
| 368 | const unsigned long available_memory = dtc->avail; |
| 369 | struct dirty_throttle_control *gdtc = mdtc_gdtc(dtc); |
| 370 | unsigned long bytes = vm_dirty_bytes; |
| 371 | unsigned long bg_bytes = dirty_background_bytes; |
| 372 | unsigned long ratio = vm_dirty_ratio; |
| 373 | unsigned long bg_ratio = dirty_background_ratio; |
| 374 | unsigned long thresh; |
| 375 | unsigned long bg_thresh; |
| 376 | struct task_struct *tsk; |
| 377 | |
| 378 | /* gdtc is !NULL iff @dtc is for memcg domain */ |
| 379 | if (gdtc) { |
| 380 | unsigned long global_avail = gdtc->avail; |
| 381 | |
| 382 | /* |
| 383 | * The byte settings can't be applied directly to memcg |
| 384 | * domains. Convert them to ratios by scaling against |
| 385 | * globally available memory. |
| 386 | */ |
| 387 | if (bytes) |
| 388 | ratio = min(DIV_ROUND_UP(bytes, PAGE_SIZE) * 100 / |
| 389 | global_avail, 100UL); |
| 390 | if (bg_bytes) |
| 391 | bg_ratio = min(DIV_ROUND_UP(bg_bytes, PAGE_SIZE) * 100 / |
| 392 | global_avail, 100UL); |
| 393 | bytes = bg_bytes = 0; |
| 394 | } |
| 395 | |
| 396 | if (bytes) |
| 397 | thresh = DIV_ROUND_UP(bytes, PAGE_SIZE); |
| 398 | else |
| 399 | thresh = (ratio * available_memory) / 100; |
| 400 | |
| 401 | if (bg_bytes) |
| 402 | bg_thresh = DIV_ROUND_UP(bg_bytes, PAGE_SIZE); |
| 403 | else |
| 404 | bg_thresh = (bg_ratio * available_memory) / 100; |
| 405 | |
| 406 | if (bg_thresh >= thresh) |
| 407 | bg_thresh = thresh / 2; |
| 408 | tsk = current; |
| 409 | if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) { |
| 410 | bg_thresh += bg_thresh / 4; |
| 411 | thresh += thresh / 4; |
| 412 | } |
| 413 | dtc->thresh = thresh; |
| 414 | dtc->bg_thresh = bg_thresh; |
| 415 | |
| 416 | /* we should eventually report the domain in the TP */ |
| 417 | if (!gdtc) |
| 418 | trace_global_dirty_state(bg_thresh, thresh); |
| 419 | } |
| 420 | |
| 421 | /** |
| 422 | * global_dirty_limits - background-writeback and dirty-throttling thresholds |
| 423 | * @pbackground: out parameter for bg_thresh |
| 424 | * @pdirty: out parameter for thresh |
| 425 | * |
| 426 | * Calculate bg_thresh and thresh for global_wb_domain. See |
| 427 | * domain_dirty_limits() for details. |
| 428 | */ |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 429 | void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty) |
| 430 | { |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 431 | struct dirty_throttle_control gdtc = { GDTC_INIT_NO_WB }; |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 432 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 433 | gdtc.avail = global_dirtyable_memory(); |
| 434 | domain_dirty_limits(&gdtc); |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 435 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 436 | *pbackground = gdtc.bg_thresh; |
| 437 | *pdirty = gdtc.thresh; |
Johannes Weiner | ccafa28 | 2012-01-10 15:07:44 -0800 | [diff] [blame] | 438 | } |
| 439 | |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 440 | /** |
Johannes Weiner | a756cf5 | 2012-01-10 15:07:49 -0800 | [diff] [blame] | 441 | * zone_dirty_limit - maximum number of dirty pages allowed in a zone |
| 442 | * @zone: the zone |
| 443 | * |
| 444 | * Returns the maximum number of dirty pages allowed in a zone, based |
| 445 | * on the zone's dirtyable memory. |
| 446 | */ |
| 447 | static unsigned long zone_dirty_limit(struct zone *zone) |
| 448 | { |
| 449 | unsigned long zone_memory = zone_dirtyable_memory(zone); |
| 450 | struct task_struct *tsk = current; |
| 451 | unsigned long dirty; |
| 452 | |
| 453 | if (vm_dirty_bytes) |
| 454 | dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE) * |
| 455 | zone_memory / global_dirtyable_memory(); |
| 456 | else |
| 457 | dirty = vm_dirty_ratio * zone_memory / 100; |
| 458 | |
| 459 | if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) |
| 460 | dirty += dirty / 4; |
| 461 | |
| 462 | return dirty; |
| 463 | } |
| 464 | |
| 465 | /** |
| 466 | * zone_dirty_ok - tells whether a zone is within its dirty limits |
| 467 | * @zone: the zone to check |
| 468 | * |
| 469 | * Returns %true when the dirty pages in @zone are within the zone's |
| 470 | * dirty limit, %false if the limit is exceeded. |
| 471 | */ |
| 472 | bool zone_dirty_ok(struct zone *zone) |
| 473 | { |
| 474 | unsigned long limit = zone_dirty_limit(zone); |
| 475 | |
| 476 | return zone_page_state(zone, NR_FILE_DIRTY) + |
| 477 | zone_page_state(zone, NR_UNSTABLE_NFS) + |
| 478 | zone_page_state(zone, NR_WRITEBACK) <= limit; |
| 479 | } |
| 480 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 481 | int dirty_background_ratio_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 482 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 483 | loff_t *ppos) |
| 484 | { |
| 485 | int ret; |
| 486 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 487 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 488 | if (ret == 0 && write) |
| 489 | dirty_background_bytes = 0; |
| 490 | return ret; |
| 491 | } |
| 492 | |
| 493 | int dirty_background_bytes_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 494 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 495 | loff_t *ppos) |
| 496 | { |
| 497 | int ret; |
| 498 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 499 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 500 | if (ret == 0 && write) |
| 501 | dirty_background_ratio = 0; |
| 502 | return ret; |
| 503 | } |
| 504 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 505 | int dirty_ratio_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 506 | void __user *buffer, size_t *lenp, |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 507 | loff_t *ppos) |
| 508 | { |
| 509 | int old_ratio = vm_dirty_ratio; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 510 | int ret; |
| 511 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 512 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 513 | if (ret == 0 && write && vm_dirty_ratio != old_ratio) { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 514 | writeback_set_ratelimit(); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 515 | vm_dirty_bytes = 0; |
| 516 | } |
| 517 | return ret; |
| 518 | } |
| 519 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 520 | int dirty_bytes_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 521 | void __user *buffer, size_t *lenp, |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 522 | loff_t *ppos) |
| 523 | { |
Sven Wegener | fc3501d | 2009-02-11 13:04:23 -0800 | [diff] [blame] | 524 | unsigned long old_bytes = vm_dirty_bytes; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 525 | int ret; |
| 526 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 527 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 528 | if (ret == 0 && write && vm_dirty_bytes != old_bytes) { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 529 | writeback_set_ratelimit(); |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 530 | vm_dirty_ratio = 0; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 531 | } |
| 532 | return ret; |
| 533 | } |
| 534 | |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 535 | static unsigned long wp_next_time(unsigned long cur_time) |
| 536 | { |
| 537 | cur_time += VM_COMPLETIONS_PERIOD_LEN; |
| 538 | /* 0 has a special meaning... */ |
| 539 | if (!cur_time) |
| 540 | return 1; |
| 541 | return cur_time; |
| 542 | } |
| 543 | |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 544 | static void wb_domain_writeout_inc(struct wb_domain *dom, |
| 545 | struct fprop_local_percpu *completions, |
| 546 | unsigned int max_prop_frac) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 547 | { |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 548 | __fprop_inc_percpu_max(&dom->completions, completions, |
| 549 | max_prop_frac); |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 550 | /* First event after period switching was turned off? */ |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 551 | if (!unlikely(dom->period_time)) { |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 552 | /* |
| 553 | * We can race with other __bdi_writeout_inc calls here but |
| 554 | * it does not cause any harm since the resulting time when |
| 555 | * timer will fire and what is in writeout_period_time will be |
| 556 | * roughly the same. |
| 557 | */ |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 558 | dom->period_time = wp_next_time(jiffies); |
| 559 | mod_timer(&dom->period_timer, dom->period_time); |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 560 | } |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 561 | } |
| 562 | |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 563 | /* |
| 564 | * Increment @wb's writeout completion count and the global writeout |
| 565 | * completion count. Called from test_clear_page_writeback(). |
| 566 | */ |
| 567 | static inline void __wb_writeout_inc(struct bdi_writeback *wb) |
| 568 | { |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 569 | struct wb_domain *cgdom; |
| 570 | |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 571 | __inc_wb_stat(wb, WB_WRITTEN); |
| 572 | wb_domain_writeout_inc(&global_wb_domain, &wb->completions, |
| 573 | wb->bdi->max_prop_frac); |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 574 | |
| 575 | cgdom = mem_cgroup_wb_domain(wb); |
| 576 | if (cgdom) |
| 577 | wb_domain_writeout_inc(cgdom, wb_memcg_completions(wb), |
| 578 | wb->bdi->max_prop_frac); |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 579 | } |
| 580 | |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 581 | void wb_writeout_inc(struct bdi_writeback *wb) |
Miklos Szeredi | dd5656e | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 582 | { |
| 583 | unsigned long flags; |
| 584 | |
| 585 | local_irq_save(flags); |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 586 | __wb_writeout_inc(wb); |
Miklos Szeredi | dd5656e | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 587 | local_irq_restore(flags); |
| 588 | } |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 589 | EXPORT_SYMBOL_GPL(wb_writeout_inc); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 590 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 591 | /* |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 592 | * On idle system, we can be called long after we scheduled because we use |
| 593 | * deferred timers so count with missed periods. |
| 594 | */ |
| 595 | static void writeout_period(unsigned long t) |
| 596 | { |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 597 | struct wb_domain *dom = (void *)t; |
| 598 | int miss_periods = (jiffies - dom->period_time) / |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 599 | VM_COMPLETIONS_PERIOD_LEN; |
| 600 | |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 601 | if (fprop_new_period(&dom->completions, miss_periods + 1)) { |
| 602 | dom->period_time = wp_next_time(dom->period_time + |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 603 | miss_periods * VM_COMPLETIONS_PERIOD_LEN); |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 604 | mod_timer(&dom->period_timer, dom->period_time); |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 605 | } else { |
| 606 | /* |
| 607 | * Aging has zeroed all fractions. Stop wasting CPU on period |
| 608 | * updates. |
| 609 | */ |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 610 | dom->period_time = 0; |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 611 | } |
| 612 | } |
| 613 | |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 614 | int wb_domain_init(struct wb_domain *dom, gfp_t gfp) |
| 615 | { |
| 616 | memset(dom, 0, sizeof(*dom)); |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 617 | |
| 618 | spin_lock_init(&dom->lock); |
| 619 | |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 620 | init_timer_deferrable(&dom->period_timer); |
| 621 | dom->period_timer.function = writeout_period; |
| 622 | dom->period_timer.data = (unsigned long)dom; |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 623 | |
| 624 | dom->dirty_limit_tstamp = jiffies; |
| 625 | |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 626 | return fprop_global_init(&dom->completions, gfp); |
| 627 | } |
| 628 | |
Tejun Heo | 841710a | 2015-05-22 18:23:33 -0400 | [diff] [blame] | 629 | #ifdef CONFIG_CGROUP_WRITEBACK |
| 630 | void wb_domain_exit(struct wb_domain *dom) |
| 631 | { |
| 632 | del_timer_sync(&dom->period_timer); |
| 633 | fprop_global_destroy(&dom->completions); |
| 634 | } |
| 635 | #endif |
| 636 | |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 637 | /* |
Johannes Weiner | d08c429 | 2011-10-31 17:07:05 -0700 | [diff] [blame] | 638 | * bdi_min_ratio keeps the sum of the minimum dirty shares of all |
| 639 | * registered backing devices, which, for obvious reasons, can not |
| 640 | * exceed 100%. |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 641 | */ |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 642 | static unsigned int bdi_min_ratio; |
| 643 | |
| 644 | int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) |
| 645 | { |
| 646 | int ret = 0; |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 647 | |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 648 | spin_lock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 649 | if (min_ratio > bdi->max_ratio) { |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 650 | ret = -EINVAL; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 651 | } else { |
| 652 | min_ratio -= bdi->min_ratio; |
| 653 | if (bdi_min_ratio + min_ratio < 100) { |
| 654 | bdi_min_ratio += min_ratio; |
| 655 | bdi->min_ratio += min_ratio; |
| 656 | } else { |
| 657 | ret = -EINVAL; |
| 658 | } |
| 659 | } |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 660 | spin_unlock_bh(&bdi_lock); |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 661 | |
| 662 | return ret; |
| 663 | } |
| 664 | |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 665 | int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) |
| 666 | { |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 667 | int ret = 0; |
| 668 | |
| 669 | if (max_ratio > 100) |
| 670 | return -EINVAL; |
| 671 | |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 672 | spin_lock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 673 | if (bdi->min_ratio > max_ratio) { |
| 674 | ret = -EINVAL; |
| 675 | } else { |
| 676 | bdi->max_ratio = max_ratio; |
Jan Kara | eb608e3 | 2012-05-24 18:59:11 +0200 | [diff] [blame] | 677 | bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 678 | } |
Jens Axboe | cfc4ba5 | 2009-09-14 13:12:40 +0200 | [diff] [blame] | 679 | spin_unlock_bh(&bdi_lock); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 680 | |
| 681 | return ret; |
| 682 | } |
| 683 | EXPORT_SYMBOL(bdi_set_max_ratio); |
| 684 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 685 | static unsigned long dirty_freerun_ceiling(unsigned long thresh, |
| 686 | unsigned long bg_thresh) |
| 687 | { |
| 688 | return (thresh + bg_thresh) / 2; |
| 689 | } |
| 690 | |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 691 | static unsigned long hard_dirty_limit(struct wb_domain *dom, |
| 692 | unsigned long thresh) |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 693 | { |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 694 | return max(thresh, dom->dirty_limit); |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 695 | } |
| 696 | |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 697 | /* |
| 698 | * Memory which can be further allocated to a memcg domain is capped by |
| 699 | * system-wide clean memory excluding the amount being used in the domain. |
| 700 | */ |
| 701 | static void mdtc_calc_avail(struct dirty_throttle_control *mdtc, |
| 702 | unsigned long filepages, unsigned long headroom) |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 703 | { |
| 704 | struct dirty_throttle_control *gdtc = mdtc_gdtc(mdtc); |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 705 | unsigned long clean = filepages - min(filepages, mdtc->dirty); |
| 706 | unsigned long global_clean = gdtc->avail - min(gdtc->avail, gdtc->dirty); |
| 707 | unsigned long other_clean = global_clean - min(global_clean, clean); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 708 | |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 709 | mdtc->avail = filepages + min(headroom, other_clean); |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 710 | } |
| 711 | |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 712 | /** |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 713 | * __wb_calc_thresh - @wb's share of dirty throttling threshold |
| 714 | * @dtc: dirty_throttle_context of interest |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 715 | * |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 716 | * Returns @wb's dirty limit in pages. The term "dirty" in the context of |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 717 | * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages. |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 718 | * |
| 719 | * Note that balance_dirty_pages() will only seriously take it as a hard limit |
| 720 | * when sleeping max_pause per page is not enough to keep the dirty pages under |
| 721 | * control. For example, when the device is completely stalled due to some error |
| 722 | * conditions, or when there are 1000 dd tasks writing to a slow 10MB/s USB key. |
| 723 | * In the other normal situations, it acts more gently by throttling the tasks |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 724 | * more (rather than completely block them) when the wb dirty pages go high. |
Wu Fengguang | 6f71865 | 2011-03-02 17:14:34 -0600 | [diff] [blame] | 725 | * |
| 726 | * 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] | 727 | * - starving fast devices |
| 728 | * - piling up dirty pages (that will take long time to sync) on slow devices |
| 729 | * |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 730 | * The wb's share of dirty limit will be adapting to its throughput and |
Wu Fengguang | 1babe18 | 2010-08-11 14:17:40 -0700 | [diff] [blame] | 731 | * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set. |
| 732 | */ |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 733 | static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc) |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 734 | { |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 735 | struct wb_domain *dom = dtc_dom(dtc); |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 736 | unsigned long thresh = dtc->thresh; |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 737 | u64 wb_thresh; |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 738 | long numerator, denominator; |
Tejun Heo | 693108a | 2015-05-22 17:13:49 -0400 | [diff] [blame] | 739 | unsigned long wb_min_ratio, wb_max_ratio; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 740 | |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 741 | /* |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 742 | * Calculate this BDI's share of the thresh ratio. |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 743 | */ |
Tejun Heo | e9770b3 | 2015-05-22 18:23:27 -0400 | [diff] [blame] | 744 | fprop_fraction_percpu(&dom->completions, dtc->wb_completions, |
Tejun Heo | 380c27c | 2015-05-22 18:23:21 -0400 | [diff] [blame] | 745 | &numerator, &denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 746 | |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 747 | wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100; |
| 748 | wb_thresh *= numerator; |
| 749 | do_div(wb_thresh, denominator); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 750 | |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 751 | wb_min_max_ratio(dtc->wb, &wb_min_ratio, &wb_max_ratio); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 752 | |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 753 | wb_thresh += (thresh * wb_min_ratio) / 100; |
| 754 | if (wb_thresh > (thresh * wb_max_ratio) / 100) |
| 755 | wb_thresh = thresh * wb_max_ratio / 100; |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 756 | |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 757 | return wb_thresh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 758 | } |
| 759 | |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 760 | unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh) |
| 761 | { |
| 762 | struct dirty_throttle_control gdtc = { GDTC_INIT(wb), |
| 763 | .thresh = thresh }; |
| 764 | return __wb_calc_thresh(&gdtc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 765 | } |
| 766 | |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 767 | /* |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 768 | * setpoint - dirty 3 |
| 769 | * f(dirty) := 1.0 + (----------------) |
| 770 | * limit - setpoint |
| 771 | * |
| 772 | * it's a 3rd order polynomial that subjects to |
| 773 | * |
| 774 | * (1) f(freerun) = 2.0 => rampup dirty_ratelimit reasonably fast |
| 775 | * (2) f(setpoint) = 1.0 => the balance point |
| 776 | * (3) f(limit) = 0 => the hard limit |
| 777 | * (4) df/dx <= 0 => negative feedback control |
| 778 | * (5) the closer to setpoint, the smaller |df/dx| (and the reverse) |
| 779 | * => fast response on large errors; small oscillation near setpoint |
| 780 | */ |
Rik van Riel | d5c9fde | 2014-05-06 12:50:01 -0700 | [diff] [blame] | 781 | static long long pos_ratio_polynom(unsigned long setpoint, |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 782 | unsigned long dirty, |
| 783 | unsigned long limit) |
| 784 | { |
| 785 | long long pos_ratio; |
| 786 | long x; |
| 787 | |
Rik van Riel | d5c9fde | 2014-05-06 12:50:01 -0700 | [diff] [blame] | 788 | x = div64_s64(((s64)setpoint - (s64)dirty) << RATELIMIT_CALC_SHIFT, |
Tejun Heo | 464d138 | 2015-04-21 16:49:13 -0400 | [diff] [blame] | 789 | (limit - setpoint) | 1); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 790 | pos_ratio = x; |
| 791 | pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT; |
| 792 | pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT; |
| 793 | pos_ratio += 1 << RATELIMIT_CALC_SHIFT; |
| 794 | |
| 795 | return clamp(pos_ratio, 0LL, 2LL << RATELIMIT_CALC_SHIFT); |
| 796 | } |
| 797 | |
| 798 | /* |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 799 | * Dirty position control. |
| 800 | * |
| 801 | * (o) global/bdi setpoints |
| 802 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 803 | * We want the dirty pages be balanced around the global/wb setpoints. |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 804 | * When the number of dirty pages is higher/lower than the setpoint, the |
| 805 | * dirty position control ratio (and hence task dirty ratelimit) will be |
| 806 | * decreased/increased to bring the dirty pages back to the setpoint. |
| 807 | * |
| 808 | * pos_ratio = 1 << RATELIMIT_CALC_SHIFT |
| 809 | * |
| 810 | * if (dirty < setpoint) scale up pos_ratio |
| 811 | * if (dirty > setpoint) scale down pos_ratio |
| 812 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 813 | * if (wb_dirty < wb_setpoint) scale up pos_ratio |
| 814 | * if (wb_dirty > wb_setpoint) scale down pos_ratio |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 815 | * |
| 816 | * task_ratelimit = dirty_ratelimit * pos_ratio >> RATELIMIT_CALC_SHIFT |
| 817 | * |
| 818 | * (o) global control line |
| 819 | * |
| 820 | * ^ pos_ratio |
| 821 | * | |
| 822 | * | |<===== global dirty control scope ======>| |
| 823 | * 2.0 .............* |
| 824 | * | .* |
| 825 | * | . * |
| 826 | * | . * |
| 827 | * | . * |
| 828 | * | . * |
| 829 | * | . * |
| 830 | * 1.0 ................................* |
| 831 | * | . . * |
| 832 | * | . . * |
| 833 | * | . . * |
| 834 | * | . . * |
| 835 | * | . . * |
| 836 | * 0 +------------.------------------.----------------------*-------------> |
| 837 | * freerun^ setpoint^ limit^ dirty pages |
| 838 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 839 | * (o) wb control line |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 840 | * |
| 841 | * ^ pos_ratio |
| 842 | * | |
| 843 | * | * |
| 844 | * | * |
| 845 | * | * |
| 846 | * | * |
| 847 | * | * |<=========== span ============>| |
| 848 | * 1.0 .......................* |
| 849 | * | . * |
| 850 | * | . * |
| 851 | * | . * |
| 852 | * | . * |
| 853 | * | . * |
| 854 | * | . * |
| 855 | * | . * |
| 856 | * | . * |
| 857 | * | . * |
| 858 | * | . * |
| 859 | * | . * |
| 860 | * 1/4 ...............................................* * * * * * * * * * * * |
| 861 | * | . . |
| 862 | * | . . |
| 863 | * | . . |
| 864 | * 0 +----------------------.-------------------------------.-------------> |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 865 | * wb_setpoint^ x_intercept^ |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 866 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 867 | * The wb control line won't drop below pos_ratio=1/4, so that wb_dirty can |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 868 | * be smoothly throttled down to normal if it starts high in situations like |
| 869 | * - start writing to a slow SD card and a fast disk at the same time. The SD |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 870 | * card's wb_dirty may rush to many times higher than wb_setpoint. |
| 871 | * - the wb dirty thresh drops quickly due to change of JBOD workload |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 872 | */ |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 873 | static void wb_position_ratio(struct dirty_throttle_control *dtc) |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 874 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 875 | struct bdi_writeback *wb = dtc->wb; |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 876 | unsigned long write_bw = wb->avg_write_bandwidth; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 877 | unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh); |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 878 | unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 879 | unsigned long wb_thresh = dtc->wb_thresh; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 880 | unsigned long x_intercept; |
| 881 | unsigned long setpoint; /* dirty pages' target balance point */ |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 882 | unsigned long wb_setpoint; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 883 | unsigned long span; |
| 884 | long long pos_ratio; /* for scaling up/down the rate limit */ |
| 885 | long x; |
| 886 | |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 887 | dtc->pos_ratio = 0; |
| 888 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 889 | if (unlikely(dtc->dirty >= limit)) |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 890 | return; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 891 | |
| 892 | /* |
| 893 | * global setpoint |
| 894 | * |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 895 | * See comment for pos_ratio_polynom(). |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 896 | */ |
| 897 | setpoint = (freerun + limit) / 2; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 898 | pos_ratio = pos_ratio_polynom(setpoint, dtc->dirty, limit); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 899 | |
| 900 | /* |
| 901 | * The strictlimit feature is a tool preventing mistrusted filesystems |
| 902 | * from growing a large number of dirty pages before throttling. For |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 903 | * such filesystems balance_dirty_pages always checks wb counters |
| 904 | * against wb limits. Even if global "nr_dirty" is under "freerun". |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 905 | * This is especially important for fuse which sets bdi->max_ratio to |
| 906 | * 1% by default. Without strictlimit feature, fuse writeback may |
| 907 | * consume arbitrary amount of RAM because it is accounted in |
| 908 | * NR_WRITEBACK_TEMP which is not involved in calculating "nr_dirty". |
| 909 | * |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 910 | * Here, in wb_position_ratio(), we calculate pos_ratio based on |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 911 | * two values: wb_dirty and wb_thresh. Let's consider an example: |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 912 | * total amount of RAM is 16GB, bdi->max_ratio is equal to 1%, global |
| 913 | * limits are set by default to 10% and 20% (background and throttle). |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 914 | * Then wb_thresh is 1% of 20% of 16GB. This amounts to ~8K pages. |
Tejun Heo | 0d960a3 | 2015-05-22 18:23:19 -0400 | [diff] [blame] | 915 | * wb_calc_thresh(wb, bg_thresh) is about ~4K pages. wb_setpoint is |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 916 | * about ~6K pages (as the average of background and throttle wb |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 917 | * limits). The 3rd order polynomial will provide positive feedback if |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 918 | * wb_dirty is under wb_setpoint and vice versa. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 919 | * |
| 920 | * Note, that we cannot use global counters in these calculations |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 921 | * because we want to throttle process writing to a strictlimit wb |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 922 | * much earlier than global "freerun" is reached (~23MB vs. ~2.3GB |
| 923 | * in the example above). |
| 924 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 925 | if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) { |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 926 | long long wb_pos_ratio; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 927 | |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 928 | if (dtc->wb_dirty < 8) { |
| 929 | dtc->pos_ratio = min_t(long long, pos_ratio * 2, |
| 930 | 2 << RATELIMIT_CALC_SHIFT); |
| 931 | return; |
| 932 | } |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 933 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 934 | if (dtc->wb_dirty >= wb_thresh) |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 935 | return; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 936 | |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 937 | wb_setpoint = dirty_freerun_ceiling(wb_thresh, |
| 938 | dtc->wb_bg_thresh); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 939 | |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 940 | if (wb_setpoint == 0 || wb_setpoint == wb_thresh) |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 941 | return; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 942 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 943 | wb_pos_ratio = pos_ratio_polynom(wb_setpoint, dtc->wb_dirty, |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 944 | wb_thresh); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 945 | |
| 946 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 947 | * Typically, for strictlimit case, wb_setpoint << setpoint |
| 948 | * and pos_ratio >> wb_pos_ratio. In the other words global |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 949 | * state ("dirty") is not limiting factor and we have to |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 950 | * make decision based on wb counters. But there is an |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 951 | * important case when global pos_ratio should get precedence: |
| 952 | * global limits are exceeded (e.g. due to activities on other |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 953 | * wb's) while given strictlimit wb is below limit. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 954 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 955 | * "pos_ratio * wb_pos_ratio" would work for the case above, |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 956 | * but it would look too non-natural for the case of all |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 957 | * activity in the system coming from a single strictlimit wb |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 958 | * with bdi->max_ratio == 100%. |
| 959 | * |
| 960 | * Note that min() below somewhat changes the dynamics of the |
| 961 | * control system. Normally, pos_ratio value can be well over 3 |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 962 | * (when globally we are at freerun and wb is well below wb |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 963 | * setpoint). Now the maximum pos_ratio in the same situation |
| 964 | * is 2. We might want to tweak this if we observe the control |
| 965 | * system is too slow to adapt. |
| 966 | */ |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 967 | dtc->pos_ratio = min(pos_ratio, wb_pos_ratio); |
| 968 | return; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 969 | } |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 970 | |
| 971 | /* |
| 972 | * We have computed basic pos_ratio above based on global situation. If |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 973 | * the wb is over/under its share of dirty pages, we want to scale |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 974 | * pos_ratio further down/up. That is done by the following mechanism. |
| 975 | */ |
| 976 | |
| 977 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 978 | * wb setpoint |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 979 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 980 | * f(wb_dirty) := 1.0 + k * (wb_dirty - wb_setpoint) |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 981 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 982 | * x_intercept - wb_dirty |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 983 | * := -------------------------- |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 984 | * x_intercept - wb_setpoint |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 985 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 986 | * The main wb control line is a linear function that subjects to |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 987 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 988 | * (1) f(wb_setpoint) = 1.0 |
| 989 | * (2) k = - 1 / (8 * write_bw) (in single wb case) |
| 990 | * or equally: x_intercept = wb_setpoint + 8 * write_bw |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 991 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 992 | * For single wb case, the dirty pages are observed to fluctuate |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 993 | * regularly within range |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 994 | * [wb_setpoint - write_bw/2, wb_setpoint + write_bw/2] |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 995 | * for various filesystems, where (2) can yield in a reasonable 12.5% |
| 996 | * fluctuation range for pos_ratio. |
| 997 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 998 | * For JBOD case, wb_thresh (not wb_dirty!) could fluctuate up to its |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 999 | * own size, so move the slope over accordingly and choose a slope that |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1000 | * yields 100% pos_ratio fluctuation on suddenly doubled wb_thresh. |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1001 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1002 | if (unlikely(wb_thresh > dtc->thresh)) |
| 1003 | wb_thresh = dtc->thresh; |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 1004 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1005 | * It's very possible that wb_thresh is close to 0 not because the |
Wu Fengguang | aed21ad | 2011-11-23 11:44:41 -0600 | [diff] [blame] | 1006 | * device is slow, but that it has remained inactive for long time. |
| 1007 | * Honour such devices a reasonable good (hopefully IO efficient) |
| 1008 | * threshold, so that the occasional writes won't be blocked and active |
| 1009 | * writes can rampup the threshold quickly. |
| 1010 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1011 | wb_thresh = max(wb_thresh, (limit - dtc->dirty) / 8); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1012 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1013 | * scale global setpoint to wb's: |
| 1014 | * wb_setpoint = setpoint * wb_thresh / thresh |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1015 | */ |
Linus Torvalds | e4bc13a | 2015-06-25 16:00:17 -0700 | [diff] [blame] | 1016 | x = div_u64((u64)wb_thresh << 16, dtc->thresh | 1); |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1017 | wb_setpoint = setpoint * (u64)x >> 16; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1018 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1019 | * Use span=(8*write_bw) in single wb case as indicated by |
| 1020 | * (thresh - wb_thresh ~= 0) and transit to wb_thresh in JBOD case. |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1021 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1022 | * wb_thresh thresh - wb_thresh |
| 1023 | * span = --------- * (8 * write_bw) + ------------------ * wb_thresh |
| 1024 | * thresh thresh |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1025 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1026 | span = (dtc->thresh - wb_thresh + 8 * write_bw) * (u64)x >> 16; |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1027 | x_intercept = wb_setpoint + span; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1028 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1029 | if (dtc->wb_dirty < x_intercept - span / 4) { |
| 1030 | pos_ratio = div64_u64(pos_ratio * (x_intercept - dtc->wb_dirty), |
Linus Torvalds | e4bc13a | 2015-06-25 16:00:17 -0700 | [diff] [blame] | 1031 | (x_intercept - wb_setpoint) | 1); |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1032 | } else |
| 1033 | pos_ratio /= 4; |
| 1034 | |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 1035 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1036 | * wb reserve area, safeguard against dirty pool underrun and disk idle |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 1037 | * It may push the desired control point of global dirty pages higher |
| 1038 | * than setpoint. |
| 1039 | */ |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1040 | x_intercept = wb_thresh / 2; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1041 | if (dtc->wb_dirty < x_intercept) { |
| 1042 | if (dtc->wb_dirty > x_intercept / 8) |
| 1043 | pos_ratio = div_u64(pos_ratio * x_intercept, |
| 1044 | dtc->wb_dirty); |
Wu Fengguang | 50657fc | 2011-10-11 17:06:33 -0600 | [diff] [blame] | 1045 | else |
Wu Fengguang | 8927f66 | 2011-08-04 22:16:46 -0600 | [diff] [blame] | 1046 | pos_ratio *= 8; |
| 1047 | } |
| 1048 | |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 1049 | dtc->pos_ratio = pos_ratio; |
Wu Fengguang | 6c14ae1 | 2011-03-02 16:04:18 -0600 | [diff] [blame] | 1050 | } |
| 1051 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1052 | static void wb_update_write_bandwidth(struct bdi_writeback *wb, |
| 1053 | unsigned long elapsed, |
| 1054 | unsigned long written) |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1055 | { |
| 1056 | const unsigned long period = roundup_pow_of_two(3 * HZ); |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1057 | unsigned long avg = wb->avg_write_bandwidth; |
| 1058 | unsigned long old = wb->write_bandwidth; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1059 | u64 bw; |
| 1060 | |
| 1061 | /* |
| 1062 | * bw = written * HZ / elapsed |
| 1063 | * |
| 1064 | * bw * elapsed + write_bandwidth * (period - elapsed) |
| 1065 | * write_bandwidth = --------------------------------------------------- |
| 1066 | * period |
Tejun Heo | c72efb6 | 2015-03-23 00:18:48 -0400 | [diff] [blame] | 1067 | * |
| 1068 | * @written may have decreased due to account_page_redirty(). |
| 1069 | * Avoid underflowing @bw calculation. |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1070 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1071 | bw = written - min(written, wb->written_stamp); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1072 | bw *= HZ; |
| 1073 | if (unlikely(elapsed > period)) { |
| 1074 | do_div(bw, elapsed); |
| 1075 | avg = bw; |
| 1076 | goto out; |
| 1077 | } |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1078 | bw += (u64)wb->write_bandwidth * (period - elapsed); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1079 | bw >>= ilog2(period); |
| 1080 | |
| 1081 | /* |
| 1082 | * one more level of smoothing, for filtering out sudden spikes |
| 1083 | */ |
| 1084 | if (avg > old && old >= (unsigned long)bw) |
| 1085 | avg -= (avg - old) >> 3; |
| 1086 | |
| 1087 | if (avg < old && old <= (unsigned long)bw) |
| 1088 | avg += (old - avg) >> 3; |
| 1089 | |
| 1090 | out: |
Tejun Heo | 95a46c6 | 2015-05-22 17:13:47 -0400 | [diff] [blame] | 1091 | /* keep avg > 0 to guarantee that tot > 0 if there are dirty wbs */ |
| 1092 | avg = max(avg, 1LU); |
| 1093 | if (wb_has_dirty_io(wb)) { |
| 1094 | long delta = avg - wb->avg_write_bandwidth; |
| 1095 | WARN_ON_ONCE(atomic_long_add_return(delta, |
| 1096 | &wb->bdi->tot_write_bandwidth) <= 0); |
| 1097 | } |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1098 | wb->write_bandwidth = bw; |
| 1099 | wb->avg_write_bandwidth = avg; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1100 | } |
| 1101 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1102 | static void update_dirty_limit(struct dirty_throttle_control *dtc) |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1103 | { |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 1104 | struct wb_domain *dom = dtc_dom(dtc); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1105 | unsigned long thresh = dtc->thresh; |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1106 | unsigned long limit = dom->dirty_limit; |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1107 | |
| 1108 | /* |
| 1109 | * Follow up in one step. |
| 1110 | */ |
| 1111 | if (limit < thresh) { |
| 1112 | limit = thresh; |
| 1113 | goto update; |
| 1114 | } |
| 1115 | |
| 1116 | /* |
| 1117 | * Follow down slowly. Use the higher one as the target, because thresh |
| 1118 | * may drop below dirty. This is exactly the reason to introduce |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1119 | * dom->dirty_limit which is guaranteed to lie above the dirty pages. |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1120 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1121 | thresh = max(thresh, dtc->dirty); |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1122 | if (limit > thresh) { |
| 1123 | limit -= (limit - thresh) >> 5; |
| 1124 | goto update; |
| 1125 | } |
| 1126 | return; |
| 1127 | update: |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1128 | dom->dirty_limit = limit; |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1129 | } |
| 1130 | |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 1131 | static void domain_update_bandwidth(struct dirty_throttle_control *dtc, |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1132 | unsigned long now) |
| 1133 | { |
Tejun Heo | e9f07df | 2015-05-22 18:23:28 -0400 | [diff] [blame] | 1134 | struct wb_domain *dom = dtc_dom(dtc); |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1135 | |
| 1136 | /* |
| 1137 | * check locklessly first to optimize away locking for the most time |
| 1138 | */ |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1139 | if (time_before(now, dom->dirty_limit_tstamp + BANDWIDTH_INTERVAL)) |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1140 | return; |
| 1141 | |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1142 | spin_lock(&dom->lock); |
| 1143 | if (time_after_eq(now, dom->dirty_limit_tstamp + BANDWIDTH_INTERVAL)) { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1144 | update_dirty_limit(dtc); |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1145 | dom->dirty_limit_tstamp = now; |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1146 | } |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 1147 | spin_unlock(&dom->lock); |
Wu Fengguang | c42843f | 2011-03-02 15:54:09 -0600 | [diff] [blame] | 1148 | } |
| 1149 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1150 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1151 | * Maintain wb->dirty_ratelimit, the base dirty throttle rate. |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1152 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1153 | * Normal wb tasks will be curbed at or below it in long term. |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1154 | * Obviously it should be around (write_bw / N) when there are N dd tasks. |
| 1155 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1156 | static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc, |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1157 | unsigned long dirtied, |
| 1158 | unsigned long elapsed) |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1159 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1160 | struct bdi_writeback *wb = dtc->wb; |
| 1161 | unsigned long dirty = dtc->dirty; |
| 1162 | unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh); |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 1163 | unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh); |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1164 | unsigned long setpoint = (freerun + limit) / 2; |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1165 | unsigned long write_bw = wb->avg_write_bandwidth; |
| 1166 | unsigned long dirty_ratelimit = wb->dirty_ratelimit; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1167 | unsigned long dirty_rate; |
| 1168 | unsigned long task_ratelimit; |
| 1169 | unsigned long balanced_dirty_ratelimit; |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1170 | unsigned long step; |
| 1171 | unsigned long x; |
Andrey Ryabinin | d59b108 | 2016-03-15 14:55:27 -0700 | [diff] [blame] | 1172 | unsigned long shift; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1173 | |
| 1174 | /* |
| 1175 | * The dirty rate will match the writeout rate in long term, except |
| 1176 | * when dirty pages are truncated by userspace or re-dirtied by FS. |
| 1177 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1178 | dirty_rate = (dirtied - wb->dirtied_stamp) * HZ / elapsed; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1179 | |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1180 | /* |
| 1181 | * task_ratelimit reflects each dd's dirty rate for the past 200ms. |
| 1182 | */ |
| 1183 | task_ratelimit = (u64)dirty_ratelimit * |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 1184 | dtc->pos_ratio >> RATELIMIT_CALC_SHIFT; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1185 | task_ratelimit++; /* it helps rampup dirty_ratelimit from tiny values */ |
| 1186 | |
| 1187 | /* |
| 1188 | * A linear estimation of the "balanced" throttle rate. The theory is, |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1189 | * if there are N dd tasks, each throttled at task_ratelimit, the wb's |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1190 | * dirty_rate will be measured to be (N * task_ratelimit). So the below |
| 1191 | * formula will yield the balanced rate limit (write_bw / N). |
| 1192 | * |
| 1193 | * Note that the expanded form is not a pure rate feedback: |
| 1194 | * rate_(i+1) = rate_(i) * (write_bw / dirty_rate) (1) |
| 1195 | * but also takes pos_ratio into account: |
| 1196 | * rate_(i+1) = rate_(i) * (write_bw / dirty_rate) * pos_ratio (2) |
| 1197 | * |
| 1198 | * (1) is not realistic because pos_ratio also takes part in balancing |
| 1199 | * the dirty rate. Consider the state |
| 1200 | * pos_ratio = 0.5 (3) |
| 1201 | * rate = 2 * (write_bw / N) (4) |
| 1202 | * If (1) is used, it will stuck in that state! Because each dd will |
| 1203 | * be throttled at |
| 1204 | * task_ratelimit = pos_ratio * rate = (write_bw / N) (5) |
| 1205 | * yielding |
| 1206 | * dirty_rate = N * task_ratelimit = write_bw (6) |
| 1207 | * put (6) into (1) we get |
| 1208 | * rate_(i+1) = rate_(i) (7) |
| 1209 | * |
| 1210 | * So we end up using (2) to always keep |
| 1211 | * rate_(i+1) ~= (write_bw / N) (8) |
| 1212 | * regardless of the value of pos_ratio. As long as (8) is satisfied, |
| 1213 | * pos_ratio is able to drive itself to 1.0, which is not only where |
| 1214 | * the dirty count meet the setpoint, but also where the slope of |
| 1215 | * pos_ratio is most flat and hence task_ratelimit is least fluctuated. |
| 1216 | */ |
| 1217 | balanced_dirty_ratelimit = div_u64((u64)task_ratelimit * write_bw, |
| 1218 | dirty_rate | 1); |
Wu Fengguang | bdaac49 | 2011-08-03 14:30:36 -0600 | [diff] [blame] | 1219 | /* |
| 1220 | * balanced_dirty_ratelimit ~= (write_bw / N) <= write_bw |
| 1221 | */ |
| 1222 | if (unlikely(balanced_dirty_ratelimit > write_bw)) |
| 1223 | balanced_dirty_ratelimit = write_bw; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1224 | |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1225 | /* |
| 1226 | * We could safely do this and return immediately: |
| 1227 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1228 | * wb->dirty_ratelimit = balanced_dirty_ratelimit; |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1229 | * |
| 1230 | * However to get a more stable dirty_ratelimit, the below elaborated |
Wanpeng Li | 331cbde | 2012-06-09 11:10:55 +0800 | [diff] [blame] | 1231 | * code makes use of task_ratelimit to filter out singular points and |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1232 | * limit the step size. |
| 1233 | * |
| 1234 | * The below code essentially only uses the relative value of |
| 1235 | * |
| 1236 | * task_ratelimit - dirty_ratelimit |
| 1237 | * = (pos_ratio - 1) * dirty_ratelimit |
| 1238 | * |
| 1239 | * which reflects the direction and size of dirty position error. |
| 1240 | */ |
| 1241 | |
| 1242 | /* |
| 1243 | * dirty_ratelimit will follow balanced_dirty_ratelimit iff |
| 1244 | * task_ratelimit is on the same side of dirty_ratelimit, too. |
| 1245 | * For example, when |
| 1246 | * - dirty_ratelimit > balanced_dirty_ratelimit |
| 1247 | * - dirty_ratelimit > task_ratelimit (dirty pages are above setpoint) |
| 1248 | * lowering dirty_ratelimit will help meet both the position and rate |
| 1249 | * control targets. Otherwise, don't update dirty_ratelimit if it will |
| 1250 | * only help meet the rate target. After all, what the users ultimately |
| 1251 | * feel and care are stable dirty rate and small position error. |
| 1252 | * |
| 1253 | * |task_ratelimit - dirty_ratelimit| is used to limit the step size |
Wanpeng Li | 331cbde | 2012-06-09 11:10:55 +0800 | [diff] [blame] | 1254 | * and filter out the singular points of balanced_dirty_ratelimit. Which |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1255 | * keeps jumping around randomly and can even leap far away at times |
| 1256 | * due to the small 200ms estimation period of dirty_rate (we want to |
| 1257 | * keep that period small to reduce time lags). |
| 1258 | */ |
| 1259 | step = 0; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1260 | |
| 1261 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1262 | * For strictlimit case, calculations above were based on wb counters |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1263 | * and limits (starting from pos_ratio = wb_position_ratio() and up to |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1264 | * balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate). |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1265 | * Hence, to calculate "step" properly, we have to use wb_dirty as |
| 1266 | * "dirty" and wb_setpoint as "setpoint". |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1267 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1268 | * We rampup dirty_ratelimit forcibly if wb_dirty is low because |
| 1269 | * it's possible that wb_thresh is close to zero due to inactivity |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1270 | * of backing device. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1271 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1272 | if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1273 | dirty = dtc->wb_dirty; |
| 1274 | if (dtc->wb_dirty < 8) |
| 1275 | setpoint = dtc->wb_dirty + 1; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1276 | else |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1277 | setpoint = (dtc->wb_thresh + dtc->wb_bg_thresh) / 2; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1278 | } |
| 1279 | |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1280 | if (dirty < setpoint) { |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1281 | x = min3(wb->balanced_dirty_ratelimit, |
Mark Rustad | 7c80996 | 2014-10-09 15:28:15 -0700 | [diff] [blame] | 1282 | balanced_dirty_ratelimit, task_ratelimit); |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1283 | if (dirty_ratelimit < x) |
| 1284 | step = x - dirty_ratelimit; |
| 1285 | } else { |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1286 | x = max3(wb->balanced_dirty_ratelimit, |
Mark Rustad | 7c80996 | 2014-10-09 15:28:15 -0700 | [diff] [blame] | 1287 | balanced_dirty_ratelimit, task_ratelimit); |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1288 | if (dirty_ratelimit > x) |
| 1289 | step = dirty_ratelimit - x; |
| 1290 | } |
| 1291 | |
| 1292 | /* |
| 1293 | * Don't pursue 100% rate matching. It's impossible since the balanced |
| 1294 | * rate itself is constantly fluctuating. So decrease the track speed |
| 1295 | * when it gets close to the target. Helps eliminate pointless tremors. |
| 1296 | */ |
Andrey Ryabinin | d59b108 | 2016-03-15 14:55:27 -0700 | [diff] [blame] | 1297 | shift = dirty_ratelimit / (2 * step + 1); |
| 1298 | if (shift < BITS_PER_LONG) |
| 1299 | step = DIV_ROUND_UP(step >> shift, 8); |
| 1300 | else |
| 1301 | step = 0; |
Wu Fengguang | 7381131 | 2011-08-26 15:53:24 -0600 | [diff] [blame] | 1302 | |
| 1303 | if (dirty_ratelimit < balanced_dirty_ratelimit) |
| 1304 | dirty_ratelimit += step; |
| 1305 | else |
| 1306 | dirty_ratelimit -= step; |
| 1307 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1308 | wb->dirty_ratelimit = max(dirty_ratelimit, 1UL); |
| 1309 | wb->balanced_dirty_ratelimit = balanced_dirty_ratelimit; |
Wu Fengguang | b48c104 | 2011-03-02 17:22:49 -0600 | [diff] [blame] | 1310 | |
Tejun Heo | 5634cc2 | 2015-08-18 14:54:56 -0700 | [diff] [blame] | 1311 | trace_bdi_dirty_ratelimit(wb, dirty_rate, task_ratelimit); |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1312 | } |
| 1313 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1314 | static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc, |
| 1315 | struct dirty_throttle_control *mdtc, |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1316 | unsigned long start_time, |
| 1317 | bool update_ratelimit) |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1318 | { |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1319 | struct bdi_writeback *wb = gdtc->wb; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1320 | unsigned long now = jiffies; |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1321 | unsigned long elapsed = now - wb->bw_time_stamp; |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1322 | unsigned long dirtied; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1323 | unsigned long written; |
| 1324 | |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1325 | lockdep_assert_held(&wb->list_lock); |
| 1326 | |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1327 | /* |
| 1328 | * rate-limit, only update once every 200ms. |
| 1329 | */ |
| 1330 | if (elapsed < BANDWIDTH_INTERVAL) |
| 1331 | return; |
| 1332 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1333 | dirtied = percpu_counter_read(&wb->stat[WB_DIRTIED]); |
| 1334 | written = percpu_counter_read(&wb->stat[WB_WRITTEN]); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1335 | |
| 1336 | /* |
| 1337 | * Skip quiet periods when disk bandwidth is under-utilized. |
| 1338 | * (at least 1s idle time between two flusher runs) |
| 1339 | */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1340 | if (elapsed > HZ && time_before(wb->bw_time_stamp, start_time)) |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1341 | goto snapshot; |
| 1342 | |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1343 | if (update_ratelimit) { |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1344 | domain_update_bandwidth(gdtc, now); |
| 1345 | wb_update_dirty_ratelimit(gdtc, dirtied, elapsed); |
| 1346 | |
| 1347 | /* |
| 1348 | * @mdtc is always NULL if !CGROUP_WRITEBACK but the |
| 1349 | * compiler has no way to figure that out. Help it. |
| 1350 | */ |
| 1351 | if (IS_ENABLED(CONFIG_CGROUP_WRITEBACK) && mdtc) { |
| 1352 | domain_update_bandwidth(mdtc, now); |
| 1353 | wb_update_dirty_ratelimit(mdtc, dirtied, elapsed); |
| 1354 | } |
Wu Fengguang | be3ffa2 | 2011-06-12 10:51:31 -0600 | [diff] [blame] | 1355 | } |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1356 | wb_update_write_bandwidth(wb, elapsed, written); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1357 | |
| 1358 | snapshot: |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1359 | wb->dirtied_stamp = dirtied; |
| 1360 | wb->written_stamp = written; |
| 1361 | wb->bw_time_stamp = now; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1362 | } |
| 1363 | |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1364 | void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time) |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1365 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1366 | struct dirty_throttle_control gdtc = { GDTC_INIT(wb) }; |
| 1367 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1368 | __wb_update_bandwidth(&gdtc, NULL, start_time, false); |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1369 | } |
| 1370 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1371 | /* |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1372 | * After a task dirtied this many pages, balance_dirty_pages_ratelimited() |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1373 | * will look to see if it needs to start dirty throttling. |
| 1374 | * |
| 1375 | * If dirty_poll_interval is too low, big NUMA machines will call the expensive |
| 1376 | * global_page_state() too often. So scale it near-sqrt to the safety margin |
| 1377 | * (the number of pages we may dirty without exceeding the dirty limits). |
| 1378 | */ |
| 1379 | static unsigned long dirty_poll_interval(unsigned long dirty, |
| 1380 | unsigned long thresh) |
| 1381 | { |
| 1382 | if (thresh > dirty) |
| 1383 | return 1UL << (ilog2(thresh - dirty) >> 1); |
| 1384 | |
| 1385 | return 1; |
| 1386 | } |
| 1387 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1388 | static unsigned long wb_max_pause(struct bdi_writeback *wb, |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1389 | unsigned long wb_dirty) |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1390 | { |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1391 | unsigned long bw = wb->avg_write_bandwidth; |
Fengguang Wu | e3b6c65 | 2013-10-16 13:47:03 -0700 | [diff] [blame] | 1392 | unsigned long t; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1393 | |
| 1394 | /* |
| 1395 | * Limit pause time for small memory systems. If sleeping for too long |
| 1396 | * time, a small pool of dirty/writeback pages may go empty and disk go |
| 1397 | * idle. |
| 1398 | * |
| 1399 | * 8 serves as the safety ratio. |
| 1400 | */ |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1401 | t = wb_dirty / (1 + bw / roundup_pow_of_two(1 + HZ / 8)); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1402 | t++; |
| 1403 | |
Fengguang Wu | e3b6c65 | 2013-10-16 13:47:03 -0700 | [diff] [blame] | 1404 | return min_t(unsigned long, t, MAX_PAUSE); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1405 | } |
| 1406 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1407 | static long wb_min_pause(struct bdi_writeback *wb, |
| 1408 | long max_pause, |
| 1409 | unsigned long task_ratelimit, |
| 1410 | unsigned long dirty_ratelimit, |
| 1411 | int *nr_dirtied_pause) |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1412 | { |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1413 | long hi = ilog2(wb->avg_write_bandwidth); |
| 1414 | long lo = ilog2(wb->dirty_ratelimit); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1415 | long t; /* target pause */ |
| 1416 | long pause; /* estimated next pause */ |
| 1417 | int pages; /* target nr_dirtied_pause */ |
| 1418 | |
| 1419 | /* target for 10ms pause on 1-dd case */ |
| 1420 | t = max(1, HZ / 100); |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1421 | |
| 1422 | /* |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1423 | * Scale up pause time for concurrent dirtiers in order to reduce CPU |
| 1424 | * overheads. |
| 1425 | * |
| 1426 | * (N * 10ms) on 2^N concurrent tasks. |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1427 | */ |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1428 | if (hi > lo) |
| 1429 | t += (hi - lo) * (10 * HZ) / 1024; |
| 1430 | |
| 1431 | /* |
| 1432 | * This is a bit convoluted. We try to base the next nr_dirtied_pause |
| 1433 | * on the much more stable dirty_ratelimit. However the next pause time |
| 1434 | * will be computed based on task_ratelimit and the two rate limits may |
| 1435 | * depart considerably at some time. Especially if task_ratelimit goes |
| 1436 | * below dirty_ratelimit/2 and the target pause is max_pause, the next |
| 1437 | * pause time will be max_pause*2 _trimmed down_ to max_pause. As a |
| 1438 | * result task_ratelimit won't be executed faithfully, which could |
| 1439 | * eventually bring down dirty_ratelimit. |
| 1440 | * |
| 1441 | * We apply two rules to fix it up: |
| 1442 | * 1) try to estimate the next pause time and if necessary, use a lower |
| 1443 | * nr_dirtied_pause so as not to exceed max_pause. When this happens, |
| 1444 | * nr_dirtied_pause will be "dancing" with task_ratelimit. |
| 1445 | * 2) limit the target pause time to max_pause/2, so that the normal |
| 1446 | * small fluctuations of task_ratelimit won't trigger rule (1) and |
| 1447 | * nr_dirtied_pause will remain as stable as dirty_ratelimit. |
| 1448 | */ |
| 1449 | t = min(t, 1 + max_pause / 2); |
| 1450 | pages = dirty_ratelimit * t / roundup_pow_of_two(HZ); |
| 1451 | |
Wu Fengguang | 5b9b357 | 2011-12-06 13:17:17 -0600 | [diff] [blame] | 1452 | /* |
| 1453 | * Tiny nr_dirtied_pause is found to hurt I/O performance in the test |
| 1454 | * case fio-mmap-randwrite-64k, which does 16*{sync read, async write}. |
| 1455 | * When the 16 consecutive reads are often interrupted by some dirty |
| 1456 | * throttling pause during the async writes, cfq will go into idles |
| 1457 | * (deadline is fine). So push nr_dirtied_pause as high as possible |
| 1458 | * until reaches DIRTY_POLL_THRESH=32 pages. |
| 1459 | */ |
| 1460 | if (pages < DIRTY_POLL_THRESH) { |
| 1461 | t = max_pause; |
| 1462 | pages = dirty_ratelimit * t / roundup_pow_of_two(HZ); |
| 1463 | if (pages > DIRTY_POLL_THRESH) { |
| 1464 | pages = DIRTY_POLL_THRESH; |
| 1465 | t = HZ * DIRTY_POLL_THRESH / dirty_ratelimit; |
| 1466 | } |
| 1467 | } |
| 1468 | |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1469 | pause = HZ * pages / (task_ratelimit + 1); |
| 1470 | if (pause > max_pause) { |
| 1471 | t = max_pause; |
| 1472 | pages = task_ratelimit * t / roundup_pow_of_two(HZ); |
| 1473 | } |
| 1474 | |
| 1475 | *nr_dirtied_pause = pages; |
| 1476 | /* |
| 1477 | * The minimal pause time will normally be half the target pause time. |
| 1478 | */ |
Wu Fengguang | 5b9b357 | 2011-12-06 13:17:17 -0600 | [diff] [blame] | 1479 | return pages >= DIRTY_POLL_THRESH ? 1 + t / 2 : t; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1480 | } |
| 1481 | |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1482 | static inline void wb_dirty_limits(struct dirty_throttle_control *dtc) |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1483 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1484 | struct bdi_writeback *wb = dtc->wb; |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 1485 | unsigned long wb_reclaimable; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1486 | |
| 1487 | /* |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1488 | * wb_thresh is not treated as some limiting factor as |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1489 | * dirty_thresh, due to reasons |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1490 | * - in JBOD setup, wb_thresh can fluctuate a lot |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1491 | * - in a system with HDD and USB key, the USB key may somehow |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1492 | * go into state (wb_dirty >> wb_thresh) either because |
| 1493 | * wb_dirty starts high, or because wb_thresh drops low. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1494 | * In this case we don't want to hard throttle the USB key |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1495 | * dirtiers for 100 seconds until wb_dirty drops under |
| 1496 | * wb_thresh. Instead the auxiliary wb control line in |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1497 | * wb_position_ratio() will let the dirtier task progress |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1498 | * at some rate <= (write_bw / 2) for bringing down wb_dirty. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1499 | */ |
Tejun Heo | b1cbc6d | 2015-05-22 18:23:25 -0400 | [diff] [blame] | 1500 | dtc->wb_thresh = __wb_calc_thresh(dtc); |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1501 | dtc->wb_bg_thresh = dtc->thresh ? |
| 1502 | div_u64((u64)dtc->wb_thresh * dtc->bg_thresh, dtc->thresh) : 0; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1503 | |
| 1504 | /* |
| 1505 | * In order to avoid the stacked BDI deadlock we need |
| 1506 | * to ensure we accurately count the 'dirty' pages when |
| 1507 | * the threshold is low. |
| 1508 | * |
| 1509 | * Otherwise it would be possible to get thresh+n pages |
| 1510 | * reported dirty, even though there are thresh-m pages |
| 1511 | * actually dirty; with m+n sitting in the percpu |
| 1512 | * deltas. |
| 1513 | */ |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1514 | if (dtc->wb_thresh < 2 * wb_stat_error(wb)) { |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 1515 | wb_reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1516 | dtc->wb_dirty = wb_reclaimable + wb_stat_sum(wb, WB_WRITEBACK); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1517 | } else { |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 1518 | wb_reclaimable = wb_stat(wb, WB_RECLAIMABLE); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1519 | dtc->wb_dirty = wb_reclaimable + wb_stat(wb, WB_WRITEBACK); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1520 | } |
| 1521 | } |
| 1522 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1523 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1524 | * balance_dirty_pages() must be called by processes which are generating dirty |
| 1525 | * 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] | 1526 | * the caller to wait once crossing the (background_thresh + dirty_thresh) / 2. |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 1527 | * If we're over `background_thresh' then the writeback threads are woken to |
| 1528 | * perform some writeout. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1529 | */ |
Wu Fengguang | 3a2e9a5 | 2009-09-23 21:56:00 +0800 | [diff] [blame] | 1530 | static void balance_dirty_pages(struct address_space *mapping, |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1531 | struct bdi_writeback *wb, |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1532 | unsigned long pages_dirtied) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1533 | { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1534 | struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) }; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1535 | struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) }; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1536 | struct dirty_throttle_control * const gdtc = &gdtc_stor; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1537 | struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ? |
| 1538 | &mdtc_stor : NULL; |
| 1539 | struct dirty_throttle_control *sdtc; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1540 | unsigned long nr_reclaimable; /* = file_dirty + unstable_nfs */ |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1541 | long period; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1542 | long pause; |
| 1543 | long max_pause; |
| 1544 | long min_pause; |
| 1545 | int nr_dirtied_pause; |
Wu Fengguang | e50e372 | 2010-08-11 14:17:37 -0700 | [diff] [blame] | 1546 | bool dirty_exceeded = false; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1547 | unsigned long task_ratelimit; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1548 | unsigned long dirty_ratelimit; |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1549 | struct backing_dev_info *bdi = wb->bdi; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1550 | bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1551 | unsigned long start_time = jiffies; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1552 | |
| 1553 | for (;;) { |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1554 | unsigned long now = jiffies; |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1555 | unsigned long dirty, thresh, bg_thresh; |
Yang Shi | 50e55bf | 2015-11-20 15:57:10 -0800 | [diff] [blame] | 1556 | unsigned long m_dirty = 0; /* stop bogus uninit warnings */ |
| 1557 | unsigned long m_thresh = 0; |
| 1558 | unsigned long m_bg_thresh = 0; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1559 | |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1560 | /* |
| 1561 | * Unstable writes are a feature of certain networked |
| 1562 | * filesystems (i.e. NFS) in which data may have been |
| 1563 | * written to the server's write cache, but has not yet |
| 1564 | * been flushed to permanent storage. |
| 1565 | */ |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1566 | nr_reclaimable = global_page_state(NR_FILE_DIRTY) + |
| 1567 | global_page_state(NR_UNSTABLE_NFS); |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 1568 | gdtc->avail = global_dirtyable_memory(); |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1569 | gdtc->dirty = nr_reclaimable + global_page_state(NR_WRITEBACK); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1570 | |
Tejun Heo | 9fc3a43 | 2015-05-22 18:23:30 -0400 | [diff] [blame] | 1571 | domain_dirty_limits(gdtc); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1572 | |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1573 | if (unlikely(strictlimit)) { |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1574 | wb_dirty_limits(gdtc); |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1575 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1576 | dirty = gdtc->wb_dirty; |
| 1577 | thresh = gdtc->wb_thresh; |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1578 | bg_thresh = gdtc->wb_bg_thresh; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1579 | } else { |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1580 | dirty = gdtc->dirty; |
| 1581 | thresh = gdtc->thresh; |
| 1582 | bg_thresh = gdtc->bg_thresh; |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1583 | } |
| 1584 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1585 | if (mdtc) { |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1586 | unsigned long filepages, headroom, writeback; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1587 | |
| 1588 | /* |
| 1589 | * If @wb belongs to !root memcg, repeat the same |
| 1590 | * basic calculations for the memcg domain. |
| 1591 | */ |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1592 | mem_cgroup_wb_stats(wb, &filepages, &headroom, |
| 1593 | &mdtc->dirty, &writeback); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1594 | mdtc->dirty += writeback; |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1595 | mdtc_calc_avail(mdtc, filepages, headroom); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1596 | |
| 1597 | domain_dirty_limits(mdtc); |
| 1598 | |
| 1599 | if (unlikely(strictlimit)) { |
| 1600 | wb_dirty_limits(mdtc); |
| 1601 | m_dirty = mdtc->wb_dirty; |
| 1602 | m_thresh = mdtc->wb_thresh; |
| 1603 | m_bg_thresh = mdtc->wb_bg_thresh; |
| 1604 | } else { |
| 1605 | m_dirty = mdtc->dirty; |
| 1606 | m_thresh = mdtc->thresh; |
| 1607 | m_bg_thresh = mdtc->bg_thresh; |
| 1608 | } |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1609 | } |
| 1610 | |
| 1611 | /* |
| 1612 | * Throttle it only when the background writeback cannot |
| 1613 | * catch-up. This avoids (excessively) small writeouts |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1614 | * when the wb limits are ramping up in case of !strictlimit. |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1615 | * |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1616 | * In strictlimit case make decision based on the wb counters |
| 1617 | * and limits. Small writeouts when the wb limits are ramping |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1618 | * up are the price we consciously pay for strictlimit-ing. |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1619 | * |
| 1620 | * If memcg domain is in effect, @dirty should be under |
| 1621 | * both global and memcg freerun ceilings. |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1622 | */ |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1623 | if (dirty <= dirty_freerun_ceiling(thresh, bg_thresh) && |
| 1624 | (!mdtc || |
| 1625 | m_dirty <= dirty_freerun_ceiling(m_thresh, m_bg_thresh))) { |
| 1626 | unsigned long intv = dirty_poll_interval(dirty, thresh); |
| 1627 | unsigned long m_intv = ULONG_MAX; |
| 1628 | |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1629 | current->dirty_paused_when = now; |
| 1630 | current->nr_dirtied = 0; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1631 | if (mdtc) |
| 1632 | m_intv = dirty_poll_interval(m_dirty, m_thresh); |
| 1633 | current->nr_dirtied_pause = min(intv, m_intv); |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1634 | break; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1635 | } |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1636 | |
Tejun Heo | bc05873 | 2015-05-22 17:13:53 -0400 | [diff] [blame] | 1637 | if (unlikely(!writeback_in_progress(wb))) |
Tejun Heo | 9ecf4866 | 2015-05-22 17:13:54 -0400 | [diff] [blame] | 1638 | wb_start_background_writeback(wb); |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1639 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1640 | /* |
| 1641 | * Calculate global domain's pos_ratio and select the |
| 1642 | * global dtc by default. |
| 1643 | */ |
Maxim Patlasov | 5a53748 | 2013-09-11 14:22:46 -0700 | [diff] [blame] | 1644 | if (!strictlimit) |
Tejun Heo | 970fb01 | 2015-05-22 18:23:24 -0400 | [diff] [blame] | 1645 | wb_dirty_limits(gdtc); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 1646 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1647 | dirty_exceeded = (gdtc->wb_dirty > gdtc->wb_thresh) && |
| 1648 | ((gdtc->dirty > gdtc->thresh) || strictlimit); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1649 | |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 1650 | wb_position_ratio(gdtc); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1651 | sdtc = gdtc; |
Wu Fengguang | e98be2d | 2010-08-29 11:22:30 -0600 | [diff] [blame] | 1652 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1653 | if (mdtc) { |
| 1654 | /* |
| 1655 | * If memcg domain is in effect, calculate its |
| 1656 | * pos_ratio. @wb should satisfy constraints from |
| 1657 | * both global and memcg domains. Choose the one |
| 1658 | * w/ lower pos_ratio. |
| 1659 | */ |
| 1660 | if (!strictlimit) |
| 1661 | wb_dirty_limits(mdtc); |
| 1662 | |
| 1663 | dirty_exceeded |= (mdtc->wb_dirty > mdtc->wb_thresh) && |
| 1664 | ((mdtc->dirty > mdtc->thresh) || strictlimit); |
| 1665 | |
| 1666 | wb_position_ratio(mdtc); |
| 1667 | if (mdtc->pos_ratio < gdtc->pos_ratio) |
| 1668 | sdtc = mdtc; |
| 1669 | } |
Tejun Heo | daddfa3 | 2015-05-22 18:23:26 -0400 | [diff] [blame] | 1670 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1671 | if (dirty_exceeded && !wb->dirty_exceeded) |
| 1672 | wb->dirty_exceeded = 1; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1673 | |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1674 | if (time_is_before_jiffies(wb->bw_time_stamp + |
| 1675 | BANDWIDTH_INTERVAL)) { |
| 1676 | spin_lock(&wb->list_lock); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1677 | __wb_update_bandwidth(gdtc, mdtc, start_time, true); |
Tejun Heo | 8a73179 | 2015-05-22 18:23:20 -0400 | [diff] [blame] | 1678 | spin_unlock(&wb->list_lock); |
| 1679 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1680 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1681 | /* throttle according to the chosen dtc */ |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1682 | dirty_ratelimit = wb->dirty_ratelimit; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1683 | task_ratelimit = ((u64)dirty_ratelimit * sdtc->pos_ratio) >> |
Wu Fengguang | 3a73dbb | 2011-11-07 19:19:28 +0800 | [diff] [blame] | 1684 | RATELIMIT_CALC_SHIFT; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1685 | max_pause = wb_max_pause(wb, sdtc->wb_dirty); |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1686 | min_pause = wb_min_pause(wb, max_pause, |
| 1687 | task_ratelimit, dirty_ratelimit, |
| 1688 | &nr_dirtied_pause); |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1689 | |
Wu Fengguang | 3a73dbb | 2011-11-07 19:19:28 +0800 | [diff] [blame] | 1690 | if (unlikely(task_ratelimit == 0)) { |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1691 | period = max_pause; |
Wu Fengguang | c8462cc | 2011-06-11 19:21:43 -0600 | [diff] [blame] | 1692 | pause = max_pause; |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1693 | goto pause; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1694 | } |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1695 | period = HZ * pages_dirtied / task_ratelimit; |
| 1696 | pause = period; |
| 1697 | if (current->dirty_paused_when) |
| 1698 | pause -= now - current->dirty_paused_when; |
| 1699 | /* |
| 1700 | * For less than 1s think time (ext3/4 may block the dirtier |
| 1701 | * for up to 800ms from time to time on 1-HDD; so does xfs, |
| 1702 | * however at much less frequency), try to compensate it in |
| 1703 | * future periods by updating the virtual time; otherwise just |
| 1704 | * do a reset, as it may be a light dirtier. |
| 1705 | */ |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1706 | if (pause < min_pause) { |
Tejun Heo | 5634cc2 | 2015-08-18 14:54:56 -0700 | [diff] [blame] | 1707 | trace_balance_dirty_pages(wb, |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1708 | sdtc->thresh, |
| 1709 | sdtc->bg_thresh, |
| 1710 | sdtc->dirty, |
| 1711 | sdtc->wb_thresh, |
| 1712 | sdtc->wb_dirty, |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1713 | dirty_ratelimit, |
| 1714 | task_ratelimit, |
| 1715 | pages_dirtied, |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1716 | period, |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1717 | min(pause, 0L), |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1718 | start_time); |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1719 | if (pause < -HZ) { |
| 1720 | current->dirty_paused_when = now; |
| 1721 | current->nr_dirtied = 0; |
| 1722 | } else if (period) { |
| 1723 | current->dirty_paused_when += period; |
| 1724 | current->nr_dirtied = 0; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1725 | } else if (current->nr_dirtied_pause <= pages_dirtied) |
| 1726 | current->nr_dirtied_pause += pages_dirtied; |
Wu Fengguang | 57fc978 | 2011-06-11 19:32:32 -0600 | [diff] [blame] | 1727 | break; |
| 1728 | } |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1729 | if (unlikely(pause > max_pause)) { |
| 1730 | /* for occasional dropped task_ratelimit */ |
| 1731 | now += min(pause - max_pause, max_pause); |
| 1732 | pause = max_pause; |
| 1733 | } |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1734 | |
| 1735 | pause: |
Tejun Heo | 5634cc2 | 2015-08-18 14:54:56 -0700 | [diff] [blame] | 1736 | trace_balance_dirty_pages(wb, |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1737 | sdtc->thresh, |
| 1738 | sdtc->bg_thresh, |
| 1739 | sdtc->dirty, |
| 1740 | sdtc->wb_thresh, |
| 1741 | sdtc->wb_dirty, |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1742 | dirty_ratelimit, |
| 1743 | task_ratelimit, |
| 1744 | pages_dirtied, |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1745 | period, |
Wu Fengguang | ece13ac | 2010-08-29 23:33:20 -0600 | [diff] [blame] | 1746 | pause, |
| 1747 | start_time); |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1748 | __set_current_state(TASK_KILLABLE); |
Wu Fengguang | d25105e | 2009-10-09 12:40:42 +0200 | [diff] [blame] | 1749 | io_schedule_timeout(pause); |
Jens Axboe | 87c6a9b | 2009-09-17 19:59:14 +0200 | [diff] [blame] | 1750 | |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1751 | current->dirty_paused_when = now + pause; |
| 1752 | current->nr_dirtied = 0; |
Wu Fengguang | 7ccb9ad | 2011-11-30 11:08:55 -0600 | [diff] [blame] | 1753 | current->nr_dirtied_pause = nr_dirtied_pause; |
Wu Fengguang | 8371235 | 2011-06-11 19:25:42 -0600 | [diff] [blame] | 1754 | |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1755 | /* |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1756 | * This is typically equal to (dirty < thresh) and can also |
| 1757 | * keep "1000+ dd on a slow USB stick" under control. |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1758 | */ |
Wu Fengguang | 1df6471 | 2011-11-13 19:47:32 -0600 | [diff] [blame] | 1759 | if (task_ratelimit) |
Wu Fengguang | ffd1f60 | 2011-06-19 22:18:42 -0600 | [diff] [blame] | 1760 | break; |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1761 | |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1762 | /* |
| 1763 | * In the case of an unresponding NFS server and the NFS dirty |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1764 | * pages exceeds dirty_thresh, give the other good wb's a pipe |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1765 | * to go through, so that tasks on them still remain responsive. |
| 1766 | * |
| 1767 | * In theory 1 page is enough to keep the comsumer-producer |
| 1768 | * pipe going: the flusher cleans 1 page => the task dirties 1 |
Tejun Heo | de1fff3 | 2015-05-22 17:13:29 -0400 | [diff] [blame] | 1769 | * more page. However wb_dirty has accounting errors. So use |
Tejun Heo | 93f78d8 | 2015-05-22 17:13:27 -0400 | [diff] [blame] | 1770 | * the larger and more IO friendly wb_stat_error. |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1771 | */ |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1772 | if (sdtc->wb_dirty <= wb_stat_error(wb)) |
Wu Fengguang | c5c6343 | 2011-12-02 10:21:33 -0600 | [diff] [blame] | 1773 | break; |
| 1774 | |
Jan Kara | 499d05e | 2011-11-16 19:34:48 +0800 | [diff] [blame] | 1775 | if (fatal_signal_pending(current)) |
| 1776 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1777 | } |
| 1778 | |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1779 | if (!dirty_exceeded && wb->dirty_exceeded) |
| 1780 | wb->dirty_exceeded = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1781 | |
Tejun Heo | bc05873 | 2015-05-22 17:13:53 -0400 | [diff] [blame] | 1782 | if (writeback_in_progress(wb)) |
Jens Axboe | 5b0830c | 2009-09-23 19:37:09 +0200 | [diff] [blame] | 1783 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1784 | |
| 1785 | /* |
| 1786 | * In laptop mode, we wait until hitting the higher threshold before |
| 1787 | * starting background writeout, and then write out all the way down |
| 1788 | * to the lower threshold. So slow writers cause minimal disk activity. |
| 1789 | * |
| 1790 | * In normal mode, we start background writeout at the lower |
| 1791 | * background_thresh, to keep the amount of dirty memory low. |
| 1792 | */ |
Wu Fengguang | 143dfe8 | 2010-08-27 18:45:12 -0600 | [diff] [blame] | 1793 | if (laptop_mode) |
| 1794 | return; |
| 1795 | |
Tejun Heo | 2bc00ae | 2015-05-22 18:23:23 -0400 | [diff] [blame] | 1796 | if (nr_reclaimable > gdtc->bg_thresh) |
Tejun Heo | 9ecf4866 | 2015-05-22 17:13:54 -0400 | [diff] [blame] | 1797 | wb_start_background_writeback(wb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1798 | } |
| 1799 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1800 | static DEFINE_PER_CPU(int, bdp_ratelimits); |
Tejun Heo | 245b2e7 | 2009-06-24 15:13:48 +0900 | [diff] [blame] | 1801 | |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1802 | /* |
| 1803 | * Normal tasks are throttled by |
| 1804 | * loop { |
| 1805 | * dirty tsk->nr_dirtied_pause pages; |
| 1806 | * take a snap in balance_dirty_pages(); |
| 1807 | * } |
| 1808 | * However there is a worst case. If every task exit immediately when dirtied |
| 1809 | * (tsk->nr_dirtied_pause - 1) pages, balance_dirty_pages() will never be |
| 1810 | * called to throttle the page dirties. The solution is to save the not yet |
| 1811 | * throttled page dirties in dirty_throttle_leaks on task exit and charge them |
| 1812 | * randomly into the running tasks. This works well for the above worst case, |
| 1813 | * as the new task will pick up and accumulate the old task's leaked dirty |
| 1814 | * count and eventually get throttled. |
| 1815 | */ |
| 1816 | DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0; |
| 1817 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1818 | /** |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1819 | * balance_dirty_pages_ratelimited - balance dirty memory state |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 1820 | * @mapping: address_space which was dirtied |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1821 | * |
| 1822 | * Processes which are dirtying memory should call in here once for each page |
| 1823 | * which was newly dirtied. The function will periodically check the system's |
| 1824 | * dirty state and will initiate writeback if needed. |
| 1825 | * |
| 1826 | * On really big machines, get_writeback_state is expensive, so try to avoid |
| 1827 | * calling it too often (ratelimiting). But once we're over the dirty memory |
| 1828 | * limit we decrease the ratelimiting by a lot, to prevent individual processes |
| 1829 | * from overshooting the limit by (ratelimit_pages) each. |
| 1830 | */ |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1831 | void balance_dirty_pages_ratelimited(struct address_space *mapping) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1832 | { |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1833 | struct inode *inode = mapping->host; |
| 1834 | struct backing_dev_info *bdi = inode_to_bdi(inode); |
| 1835 | struct bdi_writeback *wb = NULL; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1836 | int ratelimit; |
| 1837 | int *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1838 | |
Wu Fengguang | 36715ce | 2011-06-11 17:53:57 -0600 | [diff] [blame] | 1839 | if (!bdi_cap_account_dirty(bdi)) |
| 1840 | return; |
| 1841 | |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1842 | if (inode_cgwb_enabled(inode)) |
| 1843 | wb = wb_get_create_current(bdi, GFP_KERNEL); |
| 1844 | if (!wb) |
| 1845 | wb = &bdi->wb; |
| 1846 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1847 | ratelimit = current->nr_dirtied_pause; |
Tejun Heo | a88a341 | 2015-05-22 17:13:28 -0400 | [diff] [blame] | 1848 | if (wb->dirty_exceeded) |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1849 | ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1850 | |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1851 | preempt_disable(); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1852 | /* |
| 1853 | * This prevents one CPU to accumulate too many dirtied pages without |
| 1854 | * calling into balance_dirty_pages(), which can happen when there are |
| 1855 | * 1000+ tasks, all of them start dirtying pages at exactly the same |
| 1856 | * time, hence all honoured too large initial task->nr_dirtied_pause. |
| 1857 | */ |
Christoph Lameter | 7c8e018 | 2014-06-04 16:07:56 -0700 | [diff] [blame] | 1858 | p = this_cpu_ptr(&bdp_ratelimits); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1859 | if (unlikely(current->nr_dirtied >= ratelimit)) |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1860 | *p = 0; |
Wu Fengguang | d3bc1fe | 2011-04-14 07:52:37 -0600 | [diff] [blame] | 1861 | else if (unlikely(*p >= ratelimit_pages)) { |
| 1862 | *p = 0; |
| 1863 | ratelimit = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1864 | } |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1865 | /* |
| 1866 | * Pick up the dirtied pages by the exited tasks. This avoids lots of |
| 1867 | * short-lived tasks (eg. gcc invocations in a kernel build) escaping |
| 1868 | * the dirty throttling and livelock other long-run dirtiers. |
| 1869 | */ |
Christoph Lameter | 7c8e018 | 2014-06-04 16:07:56 -0700 | [diff] [blame] | 1870 | p = this_cpu_ptr(&dirty_throttle_leaks); |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1871 | if (*p > 0 && current->nr_dirtied < ratelimit) { |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1872 | unsigned long nr_pages_dirtied; |
Wu Fengguang | 54848d7 | 2011-04-05 13:21:19 -0600 | [diff] [blame] | 1873 | nr_pages_dirtied = min(*p, ratelimit - current->nr_dirtied); |
| 1874 | *p -= nr_pages_dirtied; |
| 1875 | current->nr_dirtied += nr_pages_dirtied; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1876 | } |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 1877 | preempt_enable(); |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 1878 | |
| 1879 | if (unlikely(current->nr_dirtied >= ratelimit)) |
Tejun Heo | dfb8ae5 | 2015-05-22 17:13:40 -0400 | [diff] [blame] | 1880 | balance_dirty_pages(mapping, wb, current->nr_dirtied); |
| 1881 | |
| 1882 | wb_put(wb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1883 | } |
Namjae Jeon | d0e1d66 | 2012-12-11 16:00:21 -0800 | [diff] [blame] | 1884 | EXPORT_SYMBOL(balance_dirty_pages_ratelimited); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1885 | |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1886 | /** |
| 1887 | * wb_over_bg_thresh - does @wb need to be written back? |
| 1888 | * @wb: bdi_writeback of interest |
| 1889 | * |
| 1890 | * Determines whether background writeback should keep writing @wb or it's |
| 1891 | * clean enough. Returns %true if writeback should continue. |
| 1892 | */ |
| 1893 | bool wb_over_bg_thresh(struct bdi_writeback *wb) |
| 1894 | { |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1895 | struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) }; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1896 | struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) }; |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1897 | struct dirty_throttle_control * const gdtc = &gdtc_stor; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1898 | struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ? |
| 1899 | &mdtc_stor : NULL; |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1900 | |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1901 | /* |
| 1902 | * Similar to balance_dirty_pages() but ignores pages being written |
| 1903 | * as we're trying to decide whether to put more under writeback. |
| 1904 | */ |
| 1905 | gdtc->avail = global_dirtyable_memory(); |
| 1906 | gdtc->dirty = global_page_state(NR_FILE_DIRTY) + |
| 1907 | global_page_state(NR_UNSTABLE_NFS); |
| 1908 | domain_dirty_limits(gdtc); |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1909 | |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1910 | if (gdtc->dirty > gdtc->bg_thresh) |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1911 | return true; |
| 1912 | |
Tejun Heo | 947e976 | 2015-05-22 18:23:32 -0400 | [diff] [blame] | 1913 | if (wb_stat(wb, WB_RECLAIMABLE) > __wb_calc_thresh(gdtc)) |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1914 | return true; |
| 1915 | |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1916 | if (mdtc) { |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1917 | unsigned long filepages, headroom, writeback; |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1918 | |
Tejun Heo | c5edf9c | 2015-09-29 13:04:26 -0400 | [diff] [blame] | 1919 | mem_cgroup_wb_stats(wb, &filepages, &headroom, &mdtc->dirty, |
| 1920 | &writeback); |
| 1921 | mdtc_calc_avail(mdtc, filepages, headroom); |
Tejun Heo | c2aa723 | 2015-05-22 18:23:35 -0400 | [diff] [blame] | 1922 | domain_dirty_limits(mdtc); /* ditto, ignore writeback */ |
| 1923 | |
| 1924 | if (mdtc->dirty > mdtc->bg_thresh) |
| 1925 | return true; |
| 1926 | |
| 1927 | if (wb_stat(wb, WB_RECLAIMABLE) > __wb_calc_thresh(mdtc)) |
| 1928 | return true; |
| 1929 | } |
| 1930 | |
Tejun Heo | aa661bb | 2015-05-22 18:23:31 -0400 | [diff] [blame] | 1931 | return false; |
| 1932 | } |
| 1933 | |
Andrew Morton | 232ea4d | 2007-02-28 20:13:21 -0800 | [diff] [blame] | 1934 | void throttle_vm_writeout(gfp_t gfp_mask) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1935 | { |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 1936 | unsigned long background_thresh; |
| 1937 | unsigned long dirty_thresh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1938 | |
| 1939 | for ( ; ; ) { |
Wu Fengguang | 16c4042 | 2010-08-11 14:17:39 -0700 | [diff] [blame] | 1940 | global_dirty_limits(&background_thresh, &dirty_thresh); |
Tejun Heo | c798143 | 2015-05-22 18:23:29 -0400 | [diff] [blame] | 1941 | dirty_thresh = hard_dirty_limit(&global_wb_domain, dirty_thresh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1942 | |
| 1943 | /* |
| 1944 | * Boost the allowable dirty threshold a bit for page |
| 1945 | * allocators so they don't get DoS'ed by heavy writers |
| 1946 | */ |
| 1947 | dirty_thresh += dirty_thresh / 10; /* wheeee... */ |
| 1948 | |
Christoph Lameter | c24f21b | 2006-06-30 01:55:42 -0700 | [diff] [blame] | 1949 | if (global_page_state(NR_UNSTABLE_NFS) + |
| 1950 | global_page_state(NR_WRITEBACK) <= dirty_thresh) |
| 1951 | break; |
Jens Axboe | 8aa7e84 | 2009-07-09 14:52:32 +0200 | [diff] [blame] | 1952 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
Fengguang Wu | 369f238 | 2007-10-16 23:30:45 -0700 | [diff] [blame] | 1953 | |
| 1954 | /* |
| 1955 | * The caller might hold locks which can prevent IO completion |
| 1956 | * or progress in the filesystem. So we cannot just sit here |
| 1957 | * waiting for IO to complete. |
| 1958 | */ |
| 1959 | if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) |
| 1960 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1961 | } |
| 1962 | } |
| 1963 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1964 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1965 | * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs |
| 1966 | */ |
Joe Perches | cccad5b | 2014-06-06 14:38:09 -0700 | [diff] [blame] | 1967 | int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 1968 | void __user *buffer, size_t *length, loff_t *ppos) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1969 | { |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 1970 | proc_dointvec(table, write, buffer, length, ppos); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1971 | return 0; |
| 1972 | } |
| 1973 | |
Jens Axboe | c2c4986 | 2010-05-20 09:18:47 +0200 | [diff] [blame] | 1974 | #ifdef CONFIG_BLOCK |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1975 | void laptop_mode_timer_fn(unsigned long data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1976 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1977 | struct request_queue *q = (struct request_queue *)data; |
| 1978 | int nr_pages = global_page_state(NR_FILE_DIRTY) + |
| 1979 | global_page_state(NR_UNSTABLE_NFS); |
Tejun Heo | a06fd6b | 2015-05-22 17:13:52 -0400 | [diff] [blame] | 1980 | struct bdi_writeback *wb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1981 | |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 1982 | /* |
| 1983 | * We want to write everything out, not just down to the dirty |
| 1984 | * threshold |
| 1985 | */ |
Tejun Heo | a06fd6b | 2015-05-22 17:13:52 -0400 | [diff] [blame] | 1986 | if (!bdi_has_dirty_io(&q->backing_dev_info)) |
| 1987 | return; |
| 1988 | |
Tejun Heo | 9ad18ab | 2015-09-29 12:47:50 -0400 | [diff] [blame] | 1989 | rcu_read_lock(); |
Tejun Heo | b817525 | 2015-10-02 14:47:05 -0400 | [diff] [blame] | 1990 | list_for_each_entry_rcu(wb, &q->backing_dev_info.wb_list, bdi_node) |
Tejun Heo | a06fd6b | 2015-05-22 17:13:52 -0400 | [diff] [blame] | 1991 | if (wb_has_dirty_io(wb)) |
| 1992 | wb_start_writeback(wb, nr_pages, true, |
| 1993 | WB_REASON_LAPTOP_TIMER); |
Tejun Heo | 9ad18ab | 2015-09-29 12:47:50 -0400 | [diff] [blame] | 1994 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1995 | } |
| 1996 | |
| 1997 | /* |
| 1998 | * We've spun up the disk and we're in laptop mode: schedule writeback |
| 1999 | * of all dirty data a few seconds from now. If the flush is already scheduled |
| 2000 | * then push it back - the user is still using the disk. |
| 2001 | */ |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 2002 | void laptop_io_completion(struct backing_dev_info *info) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2003 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 2004 | mod_timer(&info->laptop_mode_wb_timer, jiffies + laptop_mode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2005 | } |
| 2006 | |
| 2007 | /* |
| 2008 | * We're in laptop mode and we've just synced. The sync's writes will have |
| 2009 | * caused another writeback to be scheduled by laptop_io_completion. |
| 2010 | * Nothing needs to be written back anymore, so we unschedule the writeback. |
| 2011 | */ |
| 2012 | void laptop_sync_completion(void) |
| 2013 | { |
Matthew Garrett | 31373d0 | 2010-04-06 14:25:14 +0200 | [diff] [blame] | 2014 | struct backing_dev_info *bdi; |
| 2015 | |
| 2016 | rcu_read_lock(); |
| 2017 | |
| 2018 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) |
| 2019 | del_timer(&bdi->laptop_mode_wb_timer); |
| 2020 | |
| 2021 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2022 | } |
Jens Axboe | c2c4986 | 2010-05-20 09:18:47 +0200 | [diff] [blame] | 2023 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2024 | |
| 2025 | /* |
| 2026 | * If ratelimit_pages is too high then we can get into dirty-data overload |
| 2027 | * if a large number of processes all perform writes at the same time. |
| 2028 | * If it is too low then SMP machines will call the (expensive) |
| 2029 | * get_writeback_state too often. |
| 2030 | * |
| 2031 | * Here we set ratelimit_pages to a level which ensures that when all CPUs are |
| 2032 | * 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] | 2033 | * thresholds. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2034 | */ |
| 2035 | |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 2036 | void writeback_set_ratelimit(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2037 | { |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 2038 | struct wb_domain *dom = &global_wb_domain; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 2039 | unsigned long background_thresh; |
| 2040 | unsigned long dirty_thresh; |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 2041 | |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 2042 | global_dirty_limits(&background_thresh, &dirty_thresh); |
Tejun Heo | dcc25ae | 2015-05-22 18:23:22 -0400 | [diff] [blame] | 2043 | dom->dirty_limit = dirty_thresh; |
Wu Fengguang | 9d823e8 | 2011-06-11 18:10:12 -0600 | [diff] [blame] | 2044 | ratelimit_pages = dirty_thresh / (num_online_cpus() * 32); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2045 | if (ratelimit_pages < 16) |
| 2046 | ratelimit_pages = 16; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2047 | } |
| 2048 | |
Paul Gortmaker | 0db0628 | 2013-06-19 14:53:51 -0400 | [diff] [blame] | 2049 | static int |
Srivatsa S. Bhat | 2f60d62 | 2012-09-28 20:27:49 +0800 | [diff] [blame] | 2050 | ratelimit_handler(struct notifier_block *self, unsigned long action, |
| 2051 | void *hcpu) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2052 | { |
Srivatsa S. Bhat | 2f60d62 | 2012-09-28 20:27:49 +0800 | [diff] [blame] | 2053 | |
| 2054 | switch (action & ~CPU_TASKS_FROZEN) { |
| 2055 | case CPU_ONLINE: |
| 2056 | case CPU_DEAD: |
| 2057 | writeback_set_ratelimit(); |
| 2058 | return NOTIFY_OK; |
| 2059 | default: |
| 2060 | return NOTIFY_DONE; |
| 2061 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2062 | } |
| 2063 | |
Paul Gortmaker | 0db0628 | 2013-06-19 14:53:51 -0400 | [diff] [blame] | 2064 | static struct notifier_block ratelimit_nb = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2065 | .notifier_call = ratelimit_handler, |
| 2066 | .next = NULL, |
| 2067 | }; |
| 2068 | |
| 2069 | /* |
Linus Torvalds | dc6e29d | 2007-01-29 16:37:38 -0800 | [diff] [blame] | 2070 | * Called early on to tune the page writeback dirty limits. |
| 2071 | * |
| 2072 | * We used to scale dirty pages according to how total memory |
| 2073 | * related to pages that could be allocated for buffers (by |
| 2074 | * comparing nr_free_buffer_pages() to vm_total_pages. |
| 2075 | * |
| 2076 | * However, that was when we used "dirty_ratio" to scale with |
| 2077 | * all memory, and we don't do that any more. "dirty_ratio" |
| 2078 | * is now applied to total non-HIGHPAGE memory (by subtracting |
| 2079 | * totalhigh_pages from vm_total_pages), and as such we can't |
| 2080 | * get into the old insane situation any more where we had |
| 2081 | * large amounts of dirty pages compared to a small amount of |
| 2082 | * non-HIGHMEM memory. |
| 2083 | * |
| 2084 | * But we might still want to scale the dirty_ratio by how |
| 2085 | * much memory the box has.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2086 | */ |
| 2087 | void __init page_writeback_init(void) |
| 2088 | { |
Rabin Vincent | a50fcb5 | 2015-08-06 15:47:14 -0700 | [diff] [blame] | 2089 | BUG_ON(wb_domain_init(&global_wb_domain, GFP_KERNEL)); |
| 2090 | |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 2091 | writeback_set_ratelimit(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2092 | register_cpu_notifier(&ratelimit_nb); |
| 2093 | } |
| 2094 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2095 | /** |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2096 | * tag_pages_for_writeback - tag pages to be written by write_cache_pages |
| 2097 | * @mapping: address space structure to write |
| 2098 | * @start: starting page index |
| 2099 | * @end: ending page index (inclusive) |
| 2100 | * |
| 2101 | * This function scans the page range from @start to @end (inclusive) and tags |
| 2102 | * all pages that have DIRTY tag set with a special TOWRITE tag. The idea is |
| 2103 | * that write_cache_pages (or whoever calls this function) will then use |
| 2104 | * TOWRITE tag to identify pages eligible for writeback. This mechanism is |
| 2105 | * used to avoid livelocking of writeback by a process steadily creating new |
| 2106 | * dirty pages in the file (thus it is important for this function to be quick |
| 2107 | * so that it can tag pages faster than a dirtying process can create them). |
| 2108 | */ |
| 2109 | /* |
| 2110 | * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce tree_lock latency. |
| 2111 | */ |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2112 | void tag_pages_for_writeback(struct address_space *mapping, |
| 2113 | pgoff_t start, pgoff_t end) |
| 2114 | { |
Randy Dunlap | 3c111a0 | 2010-08-11 14:17:30 -0700 | [diff] [blame] | 2115 | #define WRITEBACK_TAG_BATCH 4096 |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2116 | unsigned long tagged; |
| 2117 | |
| 2118 | do { |
| 2119 | spin_lock_irq(&mapping->tree_lock); |
| 2120 | tagged = radix_tree_range_tag_if_tagged(&mapping->page_tree, |
| 2121 | &start, end, WRITEBACK_TAG_BATCH, |
| 2122 | PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE); |
| 2123 | spin_unlock_irq(&mapping->tree_lock); |
| 2124 | WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH); |
| 2125 | cond_resched(); |
Jan Kara | d5ed3a4 | 2010-08-19 14:13:33 -0700 | [diff] [blame] | 2126 | /* We check 'start' to handle wrapping when end == ~0UL */ |
| 2127 | } while (tagged >= WRITEBACK_TAG_BATCH && start); |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2128 | } |
| 2129 | EXPORT_SYMBOL(tag_pages_for_writeback); |
| 2130 | |
| 2131 | /** |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2132 | * 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] | 2133 | * @mapping: address space structure to write |
| 2134 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2135 | * @writepage: function called for each page |
| 2136 | * @data: data passed to writepage function |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2137 | * |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2138 | * 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] | 2139 | * if it's dirty. This is desirable behaviour for memory-cleaning writeback, |
| 2140 | * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() |
| 2141 | * and msync() need to guarantee that all the data which was dirty at the time |
| 2142 | * the call was made get new I/O started against them. If wbc->sync_mode is |
| 2143 | * WB_SYNC_ALL then we were called for data integrity and we must wait for |
| 2144 | * existing IO to complete. |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2145 | * |
| 2146 | * To avoid livelocks (when other process dirties new pages), we first tag |
| 2147 | * pages which should be written back with TOWRITE tag and only then start |
| 2148 | * writing them. For data-integrity sync we have to be careful so that we do |
| 2149 | * not miss some pages (e.g., because some other process has cleared TOWRITE |
| 2150 | * tag we set). The rule we follow is that TOWRITE tag can be cleared only |
| 2151 | * 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] | 2152 | */ |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2153 | int write_cache_pages(struct address_space *mapping, |
| 2154 | struct writeback_control *wbc, writepage_t writepage, |
| 2155 | void *data) |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2156 | { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2157 | int ret = 0; |
| 2158 | int done = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2159 | struct pagevec pvec; |
| 2160 | int nr_pages; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2161 | pgoff_t uninitialized_var(writeback_index); |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2162 | pgoff_t index; |
| 2163 | pgoff_t end; /* Inclusive */ |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2164 | pgoff_t done_index; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2165 | int cycled; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2166 | int range_whole = 0; |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2167 | int tag; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2168 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2169 | pagevec_init(&pvec, 0); |
| 2170 | if (wbc->range_cyclic) { |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2171 | writeback_index = mapping->writeback_index; /* prev offset */ |
| 2172 | index = writeback_index; |
| 2173 | if (index == 0) |
| 2174 | cycled = 1; |
| 2175 | else |
| 2176 | cycled = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2177 | end = -1; |
| 2178 | } else { |
| 2179 | index = wbc->range_start >> PAGE_CACHE_SHIFT; |
| 2180 | end = wbc->range_end >> PAGE_CACHE_SHIFT; |
| 2181 | if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) |
| 2182 | range_whole = 1; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2183 | cycled = 1; /* ignore range_cyclic tests */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2184 | } |
Wu Fengguang | 6e6938b | 2010-06-06 10:38:15 -0600 | [diff] [blame] | 2185 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2186 | tag = PAGECACHE_TAG_TOWRITE; |
| 2187 | else |
| 2188 | tag = PAGECACHE_TAG_DIRTY; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2189 | retry: |
Wu Fengguang | 6e6938b | 2010-06-06 10:38:15 -0600 | [diff] [blame] | 2190 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2191 | tag_pages_for_writeback(mapping, index, end); |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2192 | done_index = index; |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2193 | while (!done && (index <= end)) { |
| 2194 | int i; |
| 2195 | |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 2196 | nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag, |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2197 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1); |
| 2198 | if (nr_pages == 0) |
| 2199 | break; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2200 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2201 | for (i = 0; i < nr_pages; i++) { |
| 2202 | struct page *page = pvec.pages[i]; |
| 2203 | |
Nick Piggin | d5482cd | 2009-01-06 14:39:11 -0800 | [diff] [blame] | 2204 | /* |
| 2205 | * At this point, the page may be truncated or |
| 2206 | * invalidated (changing page->mapping to NULL), or |
| 2207 | * even swizzled back from swapper_space to tmpfs file |
| 2208 | * mapping. However, page->index will not change |
| 2209 | * because we have a reference on the page. |
| 2210 | */ |
| 2211 | if (page->index > end) { |
| 2212 | /* |
| 2213 | * can't be range_cyclic (1st pass) because |
| 2214 | * end == -1 in that case. |
| 2215 | */ |
| 2216 | done = 1; |
| 2217 | break; |
| 2218 | } |
| 2219 | |
Jun'ichi Nomura | cf15b07 | 2011-03-22 16:33:40 -0700 | [diff] [blame] | 2220 | done_index = page->index; |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2221 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2222 | lock_page(page); |
| 2223 | |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2224 | /* |
| 2225 | * Page truncated or invalidated. We can freely skip it |
| 2226 | * then, even for data integrity operations: the page |
| 2227 | * has disappeared concurrently, so there could be no |
| 2228 | * real expectation of this data interity operation |
| 2229 | * even if there is now a new, dirty page at the same |
| 2230 | * pagecache address. |
| 2231 | */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2232 | if (unlikely(page->mapping != mapping)) { |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2233 | continue_unlock: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2234 | unlock_page(page); |
| 2235 | continue; |
| 2236 | } |
| 2237 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 2238 | if (!PageDirty(page)) { |
| 2239 | /* someone wrote it for us */ |
| 2240 | goto continue_unlock; |
| 2241 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2242 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 2243 | if (PageWriteback(page)) { |
| 2244 | if (wbc->sync_mode != WB_SYNC_NONE) |
| 2245 | wait_on_page_writeback(page); |
| 2246 | else |
| 2247 | goto continue_unlock; |
| 2248 | } |
| 2249 | |
| 2250 | BUG_ON(PageWriteback(page)); |
| 2251 | if (!clear_page_dirty_for_io(page)) |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 2252 | goto continue_unlock; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2253 | |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2254 | trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2255 | ret = (*writepage)(page, wbc, data); |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2256 | if (unlikely(ret)) { |
| 2257 | if (ret == AOP_WRITEPAGE_ACTIVATE) { |
| 2258 | unlock_page(page); |
| 2259 | ret = 0; |
| 2260 | } else { |
| 2261 | /* |
| 2262 | * done_index is set past this page, |
| 2263 | * so media errors will not choke |
| 2264 | * background writeout for the entire |
| 2265 | * file. This has consequences for |
| 2266 | * range_cyclic semantics (ie. it may |
| 2267 | * not be suitable for data integrity |
| 2268 | * writeout). |
| 2269 | */ |
Jun'ichi Nomura | cf15b07 | 2011-03-22 16:33:40 -0700 | [diff] [blame] | 2270 | done_index = page->index + 1; |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 2271 | done = 1; |
| 2272 | break; |
| 2273 | } |
Dave Chinner | 0b56492 | 2010-06-09 10:37:18 +1000 | [diff] [blame] | 2274 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2275 | |
Dave Chinner | 546a192 | 2010-08-24 11:44:34 +1000 | [diff] [blame] | 2276 | /* |
| 2277 | * We stop writing back only if we are not doing |
| 2278 | * integrity sync. In case of integrity sync we have to |
| 2279 | * keep going until we have written all the pages |
| 2280 | * we tagged for writeback prior to entering this loop. |
| 2281 | */ |
| 2282 | if (--wbc->nr_to_write <= 0 && |
| 2283 | wbc->sync_mode == WB_SYNC_NONE) { |
| 2284 | done = 1; |
| 2285 | break; |
Nick Piggin | 05fe478 | 2009-01-06 14:39:08 -0800 | [diff] [blame] | 2286 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2287 | } |
| 2288 | pagevec_release(&pvec); |
| 2289 | cond_resched(); |
| 2290 | } |
Nick Piggin | 3a4c680 | 2009-02-12 04:34:23 +0100 | [diff] [blame] | 2291 | if (!cycled && !done) { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2292 | /* |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2293 | * range_cyclic: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2294 | * We hit the last page and there is more work to be done: wrap |
| 2295 | * back to the start of the file |
| 2296 | */ |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2297 | cycled = 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2298 | index = 0; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 2299 | end = writeback_index - 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2300 | goto retry; |
| 2301 | } |
Dave Chinner | 0b56492 | 2010-06-09 10:37:18 +1000 | [diff] [blame] | 2302 | if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) |
| 2303 | mapping->writeback_index = done_index; |
Aneesh Kumar K.V | 06d6cf6 | 2008-07-11 19:27:31 -0400 | [diff] [blame] | 2304 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2305 | return ret; |
| 2306 | } |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2307 | EXPORT_SYMBOL(write_cache_pages); |
| 2308 | |
| 2309 | /* |
| 2310 | * Function used by generic_writepages to call the real writepage |
| 2311 | * function and set the mapping flags on error |
| 2312 | */ |
| 2313 | static int __writepage(struct page *page, struct writeback_control *wbc, |
| 2314 | void *data) |
| 2315 | { |
| 2316 | struct address_space *mapping = data; |
| 2317 | int ret = mapping->a_ops->writepage(page, wbc); |
| 2318 | mapping_set_error(mapping, ret); |
| 2319 | return ret; |
| 2320 | } |
| 2321 | |
| 2322 | /** |
| 2323 | * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them. |
| 2324 | * @mapping: address space structure to write |
| 2325 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
| 2326 | * |
| 2327 | * This is a library function, which implements the writepages() |
| 2328 | * address_space_operation. |
| 2329 | */ |
| 2330 | int generic_writepages(struct address_space *mapping, |
| 2331 | struct writeback_control *wbc) |
| 2332 | { |
Shaohua Li | 9b6096a | 2011-03-17 10:47:06 +0100 | [diff] [blame] | 2333 | struct blk_plug plug; |
| 2334 | int ret; |
| 2335 | |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2336 | /* deal with chardevs and other special file */ |
| 2337 | if (!mapping->a_ops->writepage) |
| 2338 | return 0; |
| 2339 | |
Shaohua Li | 9b6096a | 2011-03-17 10:47:06 +0100 | [diff] [blame] | 2340 | blk_start_plug(&plug); |
| 2341 | ret = write_cache_pages(mapping, wbc, __writepage, mapping); |
| 2342 | blk_finish_plug(&plug); |
| 2343 | return ret; |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 2344 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 2345 | |
| 2346 | EXPORT_SYMBOL(generic_writepages); |
| 2347 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2348 | int do_writepages(struct address_space *mapping, struct writeback_control *wbc) |
| 2349 | { |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 2350 | int ret; |
| 2351 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2352 | if (wbc->nr_to_write <= 0) |
| 2353 | return 0; |
| 2354 | if (mapping->a_ops->writepages) |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 2355 | ret = mapping->a_ops->writepages(mapping, wbc); |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 2356 | else |
| 2357 | ret = generic_writepages(mapping, wbc); |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 2358 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2359 | } |
| 2360 | |
| 2361 | /** |
| 2362 | * 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] | 2363 | * @page: the page to write |
| 2364 | * @wait: if true, wait on writeout |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2365 | * |
| 2366 | * The page must be locked by the caller and will be unlocked upon return. |
| 2367 | * |
| 2368 | * write_one_page() returns a negative error code if I/O failed. |
| 2369 | */ |
| 2370 | int write_one_page(struct page *page, int wait) |
| 2371 | { |
| 2372 | struct address_space *mapping = page->mapping; |
| 2373 | int ret = 0; |
| 2374 | struct writeback_control wbc = { |
| 2375 | .sync_mode = WB_SYNC_ALL, |
| 2376 | .nr_to_write = 1, |
| 2377 | }; |
| 2378 | |
| 2379 | BUG_ON(!PageLocked(page)); |
| 2380 | |
| 2381 | if (wait) |
| 2382 | wait_on_page_writeback(page); |
| 2383 | |
| 2384 | if (clear_page_dirty_for_io(page)) { |
| 2385 | page_cache_get(page); |
| 2386 | ret = mapping->a_ops->writepage(page, &wbc); |
| 2387 | if (ret == 0 && wait) { |
| 2388 | wait_on_page_writeback(page); |
| 2389 | if (PageError(page)) |
| 2390 | ret = -EIO; |
| 2391 | } |
| 2392 | page_cache_release(page); |
| 2393 | } else { |
| 2394 | unlock_page(page); |
| 2395 | } |
| 2396 | return ret; |
| 2397 | } |
| 2398 | EXPORT_SYMBOL(write_one_page); |
| 2399 | |
| 2400 | /* |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 2401 | * For address_spaces which do not use buffers nor write back. |
| 2402 | */ |
| 2403 | int __set_page_dirty_no_writeback(struct page *page) |
| 2404 | { |
| 2405 | if (!PageDirty(page)) |
Bob Liu | c3f0da6 | 2011-01-13 15:45:49 -0800 | [diff] [blame] | 2406 | return !TestSetPageDirty(page); |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 2407 | return 0; |
| 2408 | } |
| 2409 | |
| 2410 | /* |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2411 | * Helper function for set_page_dirty family. |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2412 | * |
Johannes Weiner | 81f8c3a | 2016-03-15 14:57:04 -0700 | [diff] [blame] | 2413 | * Caller must hold lock_page_memcg(). |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2414 | * |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2415 | * NOTE: This relies on being atomic wrt interrupts. |
| 2416 | */ |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2417 | void account_page_dirtied(struct page *page, struct address_space *mapping) |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2418 | { |
Tejun Heo | 52ebea7 | 2015-05-22 17:13:37 -0400 | [diff] [blame] | 2419 | struct inode *inode = mapping->host; |
| 2420 | |
Tejun Heo | 9fb0a7d | 2013-01-11 13:06:37 -0800 | [diff] [blame] | 2421 | trace_writeback_dirty_page(page, mapping); |
| 2422 | |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2423 | if (mapping_cap_account_dirty(mapping)) { |
Tejun Heo | 52ebea7 | 2015-05-22 17:13:37 -0400 | [diff] [blame] | 2424 | struct bdi_writeback *wb; |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2425 | |
Tejun Heo | 52ebea7 | 2015-05-22 17:13:37 -0400 | [diff] [blame] | 2426 | inode_attach_wb(inode, page); |
| 2427 | wb = inode_to_wb(inode); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2428 | |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2429 | mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_DIRTY); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2430 | __inc_zone_page_state(page, NR_FILE_DIRTY); |
Michael Rubin | ea941f0 | 2010-10-26 14:21:35 -0700 | [diff] [blame] | 2431 | __inc_zone_page_state(page, NR_DIRTIED); |
Tejun Heo | 52ebea7 | 2015-05-22 17:13:37 -0400 | [diff] [blame] | 2432 | __inc_wb_stat(wb, WB_RECLAIMABLE); |
| 2433 | __inc_wb_stat(wb, WB_DIRTIED); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2434 | task_io_account_write(PAGE_CACHE_SIZE); |
Wu Fengguang | d3bc1fe | 2011-04-14 07:52:37 -0600 | [diff] [blame] | 2435 | current->nr_dirtied++; |
| 2436 | this_cpu_inc(bdp_ratelimits); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2437 | } |
| 2438 | } |
Michael Rubin | 679ceac | 2010-08-20 02:31:26 -0700 | [diff] [blame] | 2439 | EXPORT_SYMBOL(account_page_dirtied); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 2440 | |
| 2441 | /* |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2442 | * Helper function for deaccounting dirty page without writeback. |
| 2443 | * |
Johannes Weiner | 81f8c3a | 2016-03-15 14:57:04 -0700 | [diff] [blame] | 2444 | * Caller must hold lock_page_memcg(). |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2445 | */ |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2446 | void account_page_cleaned(struct page *page, struct address_space *mapping, |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2447 | struct bdi_writeback *wb) |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2448 | { |
| 2449 | if (mapping_cap_account_dirty(mapping)) { |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2450 | mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_DIRTY); |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2451 | dec_zone_page_state(page, NR_FILE_DIRTY); |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2452 | dec_wb_stat(wb, WB_RECLAIMABLE); |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2453 | task_io_account_cancelled_write(PAGE_CACHE_SIZE); |
| 2454 | } |
| 2455 | } |
Konstantin Khlebnikov | b9ea251 | 2015-04-14 15:45:27 -0700 | [diff] [blame] | 2456 | |
| 2457 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2458 | * For address_spaces which do not use buffers. Just tag the page as dirty in |
| 2459 | * its radix tree. |
| 2460 | * |
| 2461 | * This is also used when a single buffer is being dirtied: we want to set the |
| 2462 | * page dirty in that case, but not all the buffers. This is a "bottom-up" |
| 2463 | * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying. |
| 2464 | * |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2465 | * The caller must ensure this doesn't race with truncation. Most will simply |
| 2466 | * hold the page lock, but e.g. zap_pte_range() calls with the page mapped and |
| 2467 | * the pte lock held, which also locks out truncation. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2468 | */ |
| 2469 | int __set_page_dirty_nobuffers(struct page *page) |
| 2470 | { |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2471 | lock_page_memcg(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2472 | if (!TestSetPageDirty(page)) { |
| 2473 | struct address_space *mapping = page_mapping(page); |
KOSAKI Motohiro | a85d9df | 2014-02-06 12:04:24 -0800 | [diff] [blame] | 2474 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2475 | |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2476 | if (!mapping) { |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2477 | unlock_page_memcg(page); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2478 | return 1; |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2479 | } |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2480 | |
KOSAKI Motohiro | a85d9df | 2014-02-06 12:04:24 -0800 | [diff] [blame] | 2481 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2482 | BUG_ON(page_mapping(page) != mapping); |
| 2483 | WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page)); |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2484 | account_page_dirtied(page, mapping); |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2485 | radix_tree_tag_set(&mapping->page_tree, page_index(page), |
| 2486 | PAGECACHE_TAG_DIRTY); |
KOSAKI Motohiro | a85d9df | 2014-02-06 12:04:24 -0800 | [diff] [blame] | 2487 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2488 | unlock_page_memcg(page); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2489 | |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2490 | if (mapping->host) { |
| 2491 | /* !PageAnon && !swapper_space */ |
| 2492 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2493 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2494 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2495 | } |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2496 | unlock_page_memcg(page); |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2497 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2498 | } |
| 2499 | EXPORT_SYMBOL(__set_page_dirty_nobuffers); |
| 2500 | |
| 2501 | /* |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2502 | * Call this whenever redirtying a page, to de-account the dirty counters |
| 2503 | * (NR_DIRTIED, BDI_DIRTIED, tsk->nr_dirtied), so that they match the written |
| 2504 | * counters (NR_WRITTEN, BDI_WRITTEN) in long term. The mismatches will lead to |
| 2505 | * systematic errors in balanced_dirty_ratelimit and the dirty pages position |
| 2506 | * control. |
| 2507 | */ |
| 2508 | void account_page_redirty(struct page *page) |
| 2509 | { |
| 2510 | struct address_space *mapping = page->mapping; |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2511 | |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2512 | if (mapping && mapping_cap_account_dirty(mapping)) { |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2513 | struct inode *inode = mapping->host; |
| 2514 | struct bdi_writeback *wb; |
| 2515 | bool locked; |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2516 | |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2517 | wb = unlocked_inode_to_wb_begin(inode, &locked); |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2518 | current->nr_dirtied--; |
| 2519 | dec_zone_page_state(page, NR_DIRTIED); |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2520 | dec_wb_stat(wb, WB_DIRTIED); |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2521 | unlocked_inode_to_wb_end(inode, locked); |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2522 | } |
| 2523 | } |
| 2524 | EXPORT_SYMBOL(account_page_redirty); |
| 2525 | |
| 2526 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2527 | * When a writepage implementation decides that it doesn't want to write this |
| 2528 | * page for some reason, it should redirty the locked page via |
| 2529 | * redirty_page_for_writepage() and it should then unlock the page and return 0 |
| 2530 | */ |
| 2531 | int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page) |
| 2532 | { |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2533 | int ret; |
| 2534 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2535 | wbc->pages_skipped++; |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2536 | ret = __set_page_dirty_nobuffers(page); |
Wu Fengguang | 2f800fb | 2011-08-08 15:22:00 -0600 | [diff] [blame] | 2537 | account_page_redirty(page); |
Konstantin Khebnikov | 8d38633 | 2015-02-11 15:26:55 -0800 | [diff] [blame] | 2538 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2539 | } |
| 2540 | EXPORT_SYMBOL(redirty_page_for_writepage); |
| 2541 | |
| 2542 | /* |
Wu Fengguang | 6746aff | 2009-09-16 11:50:14 +0200 | [diff] [blame] | 2543 | * Dirty a page. |
| 2544 | * |
| 2545 | * For pages with a mapping this should be done under the page lock |
| 2546 | * for the benefit of asynchronous memory errors who prefer a consistent |
| 2547 | * dirty state. This rule can be broken in some special cases, |
| 2548 | * but should be better not to. |
| 2549 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2550 | * If the mapping doesn't provide a set_page_dirty a_op, then |
| 2551 | * just fall through and assume that it wants buffer_heads. |
| 2552 | */ |
Nick Piggin | 1cf6e7d | 2009-02-18 14:48:18 -0800 | [diff] [blame] | 2553 | int set_page_dirty(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2554 | { |
| 2555 | struct address_space *mapping = page_mapping(page); |
| 2556 | |
| 2557 | if (likely(mapping)) { |
| 2558 | int (*spd)(struct page *) = mapping->a_ops->set_page_dirty; |
Minchan Kim | 278df9f | 2011-03-22 16:32:54 -0700 | [diff] [blame] | 2559 | /* |
| 2560 | * readahead/lru_deactivate_page could remain |
| 2561 | * PG_readahead/PG_reclaim due to race with end_page_writeback |
| 2562 | * About readahead, if the page is written, the flags would be |
| 2563 | * reset. So no problem. |
| 2564 | * About lru_deactivate_page, if the page is redirty, the flag |
| 2565 | * will be reset. So no problem. but if the page is used by readahead |
| 2566 | * it will confuse readahead and make it restart the size rampup |
| 2567 | * process. But it's a trivial problem. |
| 2568 | */ |
Naoya Horiguchi | a4bb3ec | 2015-04-15 16:13:17 -0700 | [diff] [blame] | 2569 | if (PageReclaim(page)) |
| 2570 | ClearPageReclaim(page); |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 2571 | #ifdef CONFIG_BLOCK |
| 2572 | if (!spd) |
| 2573 | spd = __set_page_dirty_buffers; |
| 2574 | #endif |
| 2575 | return (*spd)(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2576 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 2577 | if (!PageDirty(page)) { |
| 2578 | if (!TestSetPageDirty(page)) |
| 2579 | return 1; |
| 2580 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2581 | return 0; |
| 2582 | } |
| 2583 | EXPORT_SYMBOL(set_page_dirty); |
| 2584 | |
| 2585 | /* |
| 2586 | * set_page_dirty() is racy if the caller has no reference against |
| 2587 | * page->mapping->host, and if the page is unlocked. This is because another |
| 2588 | * CPU could truncate the page off the mapping and then free the mapping. |
| 2589 | * |
| 2590 | * Usually, the page _is_ locked, or the caller is a user-space process which |
| 2591 | * holds a reference on the inode by having an open file. |
| 2592 | * |
| 2593 | * In other cases, the page should be locked before running set_page_dirty(). |
| 2594 | */ |
| 2595 | int set_page_dirty_lock(struct page *page) |
| 2596 | { |
| 2597 | int ret; |
| 2598 | |
Jens Axboe | 7eaceac | 2011-03-10 08:52:07 +0100 | [diff] [blame] | 2599 | lock_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2600 | ret = set_page_dirty(page); |
| 2601 | unlock_page(page); |
| 2602 | return ret; |
| 2603 | } |
| 2604 | EXPORT_SYMBOL(set_page_dirty_lock); |
| 2605 | |
| 2606 | /* |
Tejun Heo | 11f81be | 2015-05-22 17:13:15 -0400 | [diff] [blame] | 2607 | * This cancels just the dirty bit on the kernel page itself, it does NOT |
| 2608 | * actually remove dirty bits on any mmap's that may be around. It also |
| 2609 | * leaves the page tagged dirty, so any sync activity will still find it on |
| 2610 | * the dirty lists, and in particular, clear_page_dirty_for_io() will still |
| 2611 | * look at the dirty bits in the VM. |
| 2612 | * |
| 2613 | * Doing this should *normally* only ever be done when a page is truncated, |
| 2614 | * and is not actually mapped anywhere at all. However, fs/buffer.c does |
| 2615 | * this when it notices that somebody has cleaned out all the buffers on a |
| 2616 | * page without actually doing it through the VM. Can you say "ext3 is |
| 2617 | * horribly ugly"? Thought you could. |
| 2618 | */ |
| 2619 | void cancel_dirty_page(struct page *page) |
| 2620 | { |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2621 | struct address_space *mapping = page_mapping(page); |
| 2622 | |
| 2623 | if (mapping_cap_account_dirty(mapping)) { |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2624 | struct inode *inode = mapping->host; |
| 2625 | struct bdi_writeback *wb; |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2626 | bool locked; |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2627 | |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2628 | lock_page_memcg(page); |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2629 | wb = unlocked_inode_to_wb_begin(inode, &locked); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2630 | |
| 2631 | if (TestClearPageDirty(page)) |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2632 | account_page_cleaned(page, mapping, wb); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2633 | |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2634 | unlocked_inode_to_wb_end(inode, locked); |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2635 | unlock_page_memcg(page); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2636 | } else { |
| 2637 | ClearPageDirty(page); |
| 2638 | } |
Tejun Heo | 11f81be | 2015-05-22 17:13:15 -0400 | [diff] [blame] | 2639 | } |
| 2640 | EXPORT_SYMBOL(cancel_dirty_page); |
| 2641 | |
| 2642 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2643 | * Clear a page's dirty flag, while caring for dirty memory accounting. |
| 2644 | * Returns true if the page was previously dirty. |
| 2645 | * |
| 2646 | * This is for preparing to put the page under writeout. We leave the page |
| 2647 | * tagged as dirty in the radix tree so that a concurrent write-for-sync |
| 2648 | * can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage |
| 2649 | * implementation will run either set_page_writeback() or set_page_dirty(), |
| 2650 | * at which stage we bring the page's dirty flag and radix-tree dirty tag |
| 2651 | * back into sync. |
| 2652 | * |
| 2653 | * This incoherency between the page's dirty flag and radix-tree tag is |
| 2654 | * unfortunate, but it only exists while the page is locked. |
| 2655 | */ |
| 2656 | int clear_page_dirty_for_io(struct page *page) |
| 2657 | { |
| 2658 | struct address_space *mapping = page_mapping(page); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2659 | int ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2660 | |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2661 | BUG_ON(!PageLocked(page)); |
| 2662 | |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2663 | if (mapping && mapping_cap_account_dirty(mapping)) { |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2664 | struct inode *inode = mapping->host; |
| 2665 | struct bdi_writeback *wb; |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2666 | bool locked; |
| 2667 | |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2668 | /* |
| 2669 | * Yes, Virginia, this is indeed insane. |
| 2670 | * |
| 2671 | * We use this sequence to make sure that |
| 2672 | * (a) we account for dirty stats properly |
| 2673 | * (b) we tell the low-level filesystem to |
| 2674 | * mark the whole page dirty if it was |
| 2675 | * dirty in a pagetable. Only to then |
| 2676 | * (c) clean the page again and return 1 to |
| 2677 | * cause the writeback. |
| 2678 | * |
| 2679 | * This way we avoid all nasty races with the |
| 2680 | * dirty bit in multiple places and clearing |
| 2681 | * them concurrently from different threads. |
| 2682 | * |
| 2683 | * Note! Normally the "set_page_dirty(page)" |
| 2684 | * has no effect on the actual dirty bit - since |
| 2685 | * that will already usually be set. But we |
| 2686 | * need the side effects, and it can help us |
| 2687 | * avoid races. |
| 2688 | * |
| 2689 | * We basically use the page "master dirty bit" |
| 2690 | * as a serialization point for all the different |
| 2691 | * threads doing their things. |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2692 | */ |
| 2693 | if (page_mkclean(page)) |
| 2694 | set_page_dirty(page); |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2695 | /* |
| 2696 | * We carefully synchronise fault handlers against |
| 2697 | * installing a dirty pte and marking the page dirty |
Johannes Weiner | 2d6d7f9 | 2015-01-08 14:32:18 -0800 | [diff] [blame] | 2698 | * at this point. We do this by having them hold the |
| 2699 | * page lock while dirtying the page, and pages are |
| 2700 | * always locked coming in here, so we get the desired |
| 2701 | * exclusion. |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 2702 | */ |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2703 | wb = unlocked_inode_to_wb_begin(inode, &locked); |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2704 | if (TestClearPageDirty(page)) { |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2705 | mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_DIRTY); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 2706 | dec_zone_page_state(page, NR_FILE_DIRTY); |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2707 | dec_wb_stat(wb, WB_RECLAIMABLE); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2708 | ret = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2709 | } |
Tejun Heo | 682aa8e | 2015-05-28 14:50:53 -0400 | [diff] [blame] | 2710 | unlocked_inode_to_wb_end(inode, locked); |
Greg Thelen | c4843a7 | 2015-05-22 17:13:16 -0400 | [diff] [blame] | 2711 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2712 | } |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 2713 | return TestClearPageDirty(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2714 | } |
Hans Reiser | 58bb01a | 2005-11-18 01:10:53 -0800 | [diff] [blame] | 2715 | EXPORT_SYMBOL(clear_page_dirty_for_io); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2716 | |
| 2717 | int test_clear_page_writeback(struct page *page) |
| 2718 | { |
| 2719 | struct address_space *mapping = page_mapping(page); |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2720 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2721 | |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2722 | lock_page_memcg(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2723 | if (mapping) { |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2724 | struct inode *inode = mapping->host; |
| 2725 | struct backing_dev_info *bdi = inode_to_bdi(inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2726 | unsigned long flags; |
| 2727 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2728 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2729 | ret = TestClearPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2730 | if (ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2731 | radix_tree_tag_clear(&mapping->page_tree, |
| 2732 | page_index(page), |
| 2733 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 2734 | if (bdi_cap_account_writeback(bdi)) { |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2735 | struct bdi_writeback *wb = inode_to_wb(inode); |
| 2736 | |
| 2737 | __dec_wb_stat(wb, WB_WRITEBACK); |
| 2738 | __wb_writeout_inc(wb); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 2739 | } |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2740 | } |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2741 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2742 | } else { |
| 2743 | ret = TestClearPageWriteback(page); |
| 2744 | } |
Wu Fengguang | 99b12e3 | 2011-07-25 17:12:37 -0700 | [diff] [blame] | 2745 | if (ret) { |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2746 | mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_WRITEBACK); |
Andrew Morton | d688abf | 2007-07-19 01:49:17 -0700 | [diff] [blame] | 2747 | dec_zone_page_state(page, NR_WRITEBACK); |
Wu Fengguang | 99b12e3 | 2011-07-25 17:12:37 -0700 | [diff] [blame] | 2748 | inc_zone_page_state(page, NR_WRITTEN); |
| 2749 | } |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2750 | unlock_page_memcg(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2751 | return ret; |
| 2752 | } |
| 2753 | |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2754 | int __test_set_page_writeback(struct page *page, bool keep_write) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2755 | { |
| 2756 | struct address_space *mapping = page_mapping(page); |
Johannes Weiner | d7365e7 | 2014-10-29 14:50:48 -0700 | [diff] [blame] | 2757 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2758 | |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2759 | lock_page_memcg(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2760 | if (mapping) { |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2761 | struct inode *inode = mapping->host; |
| 2762 | struct backing_dev_info *bdi = inode_to_bdi(inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2763 | unsigned long flags; |
| 2764 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2765 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2766 | ret = TestSetPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2767 | if (!ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2768 | radix_tree_tag_set(&mapping->page_tree, |
| 2769 | page_index(page), |
| 2770 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 2771 | if (bdi_cap_account_writeback(bdi)) |
Tejun Heo | 9101813 | 2015-05-22 17:13:39 -0400 | [diff] [blame] | 2772 | __inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 2773 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2774 | if (!PageDirty(page)) |
| 2775 | radix_tree_tag_clear(&mapping->page_tree, |
| 2776 | page_index(page), |
| 2777 | PAGECACHE_TAG_DIRTY); |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2778 | if (!keep_write) |
| 2779 | radix_tree_tag_clear(&mapping->page_tree, |
| 2780 | page_index(page), |
| 2781 | PAGECACHE_TAG_TOWRITE); |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 2782 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2783 | } else { |
| 2784 | ret = TestSetPageWriteback(page); |
| 2785 | } |
Johannes Weiner | 3a3c02e | 2014-10-29 14:50:46 -0700 | [diff] [blame] | 2786 | if (!ret) { |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2787 | mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_WRITEBACK); |
Johannes Weiner | 3a3c02e | 2014-10-29 14:50:46 -0700 | [diff] [blame] | 2788 | inc_zone_page_state(page, NR_WRITEBACK); |
| 2789 | } |
Johannes Weiner | 62cccb8 | 2016-03-15 14:57:22 -0700 | [diff] [blame] | 2790 | unlock_page_memcg(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2791 | return ret; |
| 2792 | |
| 2793 | } |
Namjae Jeon | 1c8349a | 2014-05-12 08:12:25 -0400 | [diff] [blame] | 2794 | EXPORT_SYMBOL(__test_set_page_writeback); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2795 | |
| 2796 | /* |
Nick Piggin | 0012818 | 2007-10-16 01:24:40 -0700 | [diff] [blame] | 2797 | * 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] | 2798 | * passed tag. |
| 2799 | */ |
| 2800 | int mapping_tagged(struct address_space *mapping, int tag) |
| 2801 | { |
Konstantin Khlebnikov | 72c4783 | 2011-07-25 17:12:31 -0700 | [diff] [blame] | 2802 | return radix_tree_tagged(&mapping->page_tree, tag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2803 | } |
| 2804 | EXPORT_SYMBOL(mapping_tagged); |
Darrick J. Wong | 1d1d1a7 | 2013-02-21 16:42:51 -0800 | [diff] [blame] | 2805 | |
| 2806 | /** |
| 2807 | * wait_for_stable_page() - wait for writeback to finish, if necessary. |
| 2808 | * @page: The page to wait on. |
| 2809 | * |
| 2810 | * This function determines if the given page is related to a backing device |
| 2811 | * that requires page contents to be held stable during writeback. If so, then |
| 2812 | * it will wait for any pending writeback to complete. |
| 2813 | */ |
| 2814 | void wait_for_stable_page(struct page *page) |
| 2815 | { |
Christoph Hellwig | de1414a | 2015-01-14 10:42:36 +0100 | [diff] [blame] | 2816 | if (bdi_cap_stable_pages_required(inode_to_bdi(page->mapping->host))) |
| 2817 | wait_on_page_writeback(page); |
Darrick J. Wong | 1d1d1a7 | 2013-02-21 16:42:51 -0800 | [diff] [blame] | 2818 | } |
| 2819 | EXPORT_SYMBOL_GPL(wait_for_stable_page); |