Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Uwe Zeisberger | f30c226 | 2006-10-03 23:01:26 +0200 | [diff] [blame] | 2 | * mm/page-writeback.c |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * |
| 4 | * Copyright (C) 2002, Linus Torvalds. |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 5 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 6 | * |
| 7 | * Contains functions related to writing back dirty pages at the |
| 8 | * address_space level. |
| 9 | * |
Francois Cami | e1f8e87 | 2008-10-15 22:01:59 -0700 | [diff] [blame] | 10 | * 10Apr2002 Andrew Morton |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | * Initial version |
| 12 | */ |
| 13 | |
| 14 | #include <linux/kernel.h> |
| 15 | #include <linux/module.h> |
| 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> |
David Howells | cf9a2ae | 2006-08-29 19:05:54 +0100 | [diff] [blame] | 35 | #include <linux/buffer_head.h> |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 36 | #include <linux/pagevec.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | |
| 38 | /* |
| 39 | * The maximum number of pages to writeout in a single bdflush/kupdate |
Joern Engel | 1c0eeaf | 2007-10-16 23:30:44 -0700 | [diff] [blame] | 40 | * operation. We do this so we don't hold I_SYNC against an inode for |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | * enormous amounts of time, which would block a userspace task which has |
| 42 | * been forced to throttle against that inode. Also, the code reevaluates |
| 43 | * the dirty each time it has written this many pages. |
| 44 | */ |
| 45 | #define MAX_WRITEBACK_PAGES 1024 |
| 46 | |
| 47 | /* |
| 48 | * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited |
| 49 | * will look to see if it needs to force writeback or throttling. |
| 50 | */ |
| 51 | static long ratelimit_pages = 32; |
| 52 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 53 | /* |
| 54 | * When balance_dirty_pages decides that the caller needs to perform some |
| 55 | * non-background writeback, this is how many pages it will attempt to write. |
| 56 | * It should be somewhat larger than RATELIMIT_PAGES to ensure that reasonably |
| 57 | * large amounts of I/O are submitted. |
| 58 | */ |
| 59 | static inline long sync_writeback_pages(void) |
| 60 | { |
| 61 | return ratelimit_pages + ratelimit_pages / 2; |
| 62 | } |
| 63 | |
| 64 | /* The following parameters are exported via /proc/sys/vm */ |
| 65 | |
| 66 | /* |
| 67 | * Start background writeback (via pdflush) at this percentage |
| 68 | */ |
Wu Fengguang | 1b5e62b | 2009-03-23 08:57:38 +0800 | [diff] [blame] | 69 | int dirty_background_ratio = 10; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 70 | |
| 71 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 72 | * dirty_background_bytes starts at 0 (disabled) so that it is a function of |
| 73 | * dirty_background_ratio * the amount of dirtyable memory |
| 74 | */ |
| 75 | unsigned long dirty_background_bytes; |
| 76 | |
| 77 | /* |
Bron Gondwana | 195cf453 | 2008-02-04 22:29:20 -0800 | [diff] [blame] | 78 | * free highmem will not be subtracted from the total free memory |
| 79 | * for calculating free ratios if vm_highmem_is_dirtyable is true |
| 80 | */ |
| 81 | int vm_highmem_is_dirtyable; |
| 82 | |
| 83 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 84 | * The generator of dirty data starts writeback at this percentage |
| 85 | */ |
Wu Fengguang | 1b5e62b | 2009-03-23 08:57:38 +0800 | [diff] [blame] | 86 | int vm_dirty_ratio = 20; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 87 | |
| 88 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 89 | * vm_dirty_bytes starts at 0 (disabled) so that it is a function of |
| 90 | * vm_dirty_ratio * the amount of dirtyable memory |
| 91 | */ |
| 92 | unsigned long vm_dirty_bytes; |
| 93 | |
| 94 | /* |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 95 | * The interval between `kupdate'-style writebacks |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | */ |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 97 | unsigned int dirty_writeback_interval = 5 * 100; /* centiseconds */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | |
| 99 | /* |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 100 | * The longest time for which data is allowed to remain dirty |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | */ |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 102 | unsigned int dirty_expire_interval = 30 * 100; /* centiseconds */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | |
| 104 | /* |
| 105 | * Flag that makes the machine dump writes/reads and block dirtyings. |
| 106 | */ |
| 107 | int block_dump; |
| 108 | |
| 109 | /* |
Bart Samwel | ed5b43f | 2006-03-24 03:15:49 -0800 | [diff] [blame] | 110 | * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies: |
| 111 | * 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] | 112 | */ |
| 113 | int laptop_mode; |
| 114 | |
| 115 | EXPORT_SYMBOL(laptop_mode); |
| 116 | |
| 117 | /* End of sysctl-exported parameters */ |
| 118 | |
| 119 | |
| 120 | static void background_writeout(unsigned long _min_pages); |
| 121 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 122 | /* |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 123 | * Scale the writeback cache size proportional to the relative writeout speeds. |
| 124 | * |
| 125 | * We do this by keeping a floating proportion between BDIs, based on page |
| 126 | * writeback completions [end_page_writeback()]. Those devices that write out |
| 127 | * pages fastest will get the larger share, while the slower will get a smaller |
| 128 | * share. |
| 129 | * |
| 130 | * We use page writeout completions because we are interested in getting rid of |
| 131 | * dirty pages. Having them written out is the primary goal. |
| 132 | * |
| 133 | * We introduce a concept of time, a period over which we measure these events, |
| 134 | * because demand can/will vary over time. The length of this period itself is |
| 135 | * measured in page writeback completions. |
| 136 | * |
| 137 | */ |
| 138 | static struct prop_descriptor vm_completions; |
Peter Zijlstra | 3e26c14 | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 139 | static struct prop_descriptor vm_dirties; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 140 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 141 | /* |
| 142 | * couple the period to the dirty_ratio: |
| 143 | * |
| 144 | * period/2 ~ roundup_pow_of_two(dirty limit) |
| 145 | */ |
| 146 | static int calc_period_shift(void) |
| 147 | { |
| 148 | unsigned long dirty_total; |
| 149 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 150 | if (vm_dirty_bytes) |
| 151 | dirty_total = vm_dirty_bytes / PAGE_SIZE; |
| 152 | else |
| 153 | dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) / |
| 154 | 100; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 155 | return 2 + ilog2(dirty_total - 1); |
| 156 | } |
| 157 | |
| 158 | /* |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 159 | * update the period when the dirty threshold changes. |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 160 | */ |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 161 | static void update_completion_period(void) |
| 162 | { |
| 163 | int shift = calc_period_shift(); |
| 164 | prop_change_shift(&vm_completions, shift); |
| 165 | prop_change_shift(&vm_dirties, shift); |
| 166 | } |
| 167 | |
| 168 | int dirty_background_ratio_handler(struct ctl_table *table, int write, |
| 169 | struct file *filp, void __user *buffer, size_t *lenp, |
| 170 | loff_t *ppos) |
| 171 | { |
| 172 | int ret; |
| 173 | |
| 174 | ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos); |
| 175 | if (ret == 0 && write) |
| 176 | dirty_background_bytes = 0; |
| 177 | return ret; |
| 178 | } |
| 179 | |
| 180 | int dirty_background_bytes_handler(struct ctl_table *table, int write, |
| 181 | struct file *filp, void __user *buffer, size_t *lenp, |
| 182 | loff_t *ppos) |
| 183 | { |
| 184 | int ret; |
| 185 | |
| 186 | ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos); |
| 187 | if (ret == 0 && write) |
| 188 | dirty_background_ratio = 0; |
| 189 | return ret; |
| 190 | } |
| 191 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 192 | int dirty_ratio_handler(struct ctl_table *table, int write, |
| 193 | struct file *filp, void __user *buffer, size_t *lenp, |
| 194 | loff_t *ppos) |
| 195 | { |
| 196 | int old_ratio = vm_dirty_ratio; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 197 | int ret; |
| 198 | |
| 199 | ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 200 | if (ret == 0 && write && vm_dirty_ratio != old_ratio) { |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 201 | update_completion_period(); |
| 202 | vm_dirty_bytes = 0; |
| 203 | } |
| 204 | return ret; |
| 205 | } |
| 206 | |
| 207 | |
| 208 | int dirty_bytes_handler(struct ctl_table *table, int write, |
| 209 | struct file *filp, void __user *buffer, size_t *lenp, |
| 210 | loff_t *ppos) |
| 211 | { |
Sven Wegener | fc3501d | 2009-02-11 13:04:23 -0800 | [diff] [blame] | 212 | unsigned long old_bytes = vm_dirty_bytes; |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 213 | int ret; |
| 214 | |
| 215 | ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos); |
| 216 | if (ret == 0 && write && vm_dirty_bytes != old_bytes) { |
| 217 | update_completion_period(); |
| 218 | vm_dirty_ratio = 0; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 219 | } |
| 220 | return ret; |
| 221 | } |
| 222 | |
| 223 | /* |
| 224 | * Increment the BDI's writeout completion count and the global writeout |
| 225 | * completion count. Called from test_clear_page_writeback(). |
| 226 | */ |
| 227 | static inline void __bdi_writeout_inc(struct backing_dev_info *bdi) |
| 228 | { |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 229 | __prop_inc_percpu_max(&vm_completions, &bdi->completions, |
| 230 | bdi->max_prop_frac); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 231 | } |
| 232 | |
Miklos Szeredi | dd5656e | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 233 | void bdi_writeout_inc(struct backing_dev_info *bdi) |
| 234 | { |
| 235 | unsigned long flags; |
| 236 | |
| 237 | local_irq_save(flags); |
| 238 | __bdi_writeout_inc(bdi); |
| 239 | local_irq_restore(flags); |
| 240 | } |
| 241 | EXPORT_SYMBOL_GPL(bdi_writeout_inc); |
| 242 | |
Nick Piggin | 1cf6e7d | 2009-02-18 14:48:18 -0800 | [diff] [blame] | 243 | void task_dirty_inc(struct task_struct *tsk) |
Peter Zijlstra | 3e26c14 | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 244 | { |
| 245 | prop_inc_single(&vm_dirties, &tsk->dirties); |
| 246 | } |
| 247 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 248 | /* |
| 249 | * Obtain an accurate fraction of the BDI's portion. |
| 250 | */ |
| 251 | static void bdi_writeout_fraction(struct backing_dev_info *bdi, |
| 252 | long *numerator, long *denominator) |
| 253 | { |
| 254 | if (bdi_cap_writeback_dirty(bdi)) { |
| 255 | prop_fraction_percpu(&vm_completions, &bdi->completions, |
| 256 | numerator, denominator); |
| 257 | } else { |
| 258 | *numerator = 0; |
| 259 | *denominator = 1; |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | /* |
| 264 | * Clip the earned share of dirty pages to that which is actually available. |
| 265 | * This avoids exceeding the total dirty_limit when the floating averages |
| 266 | * fluctuate too quickly. |
| 267 | */ |
H Hartley Sweeten | dcf975d | 2009-06-16 15:31:44 -0700 | [diff] [blame] | 268 | static void clip_bdi_dirty_limit(struct backing_dev_info *bdi, |
| 269 | unsigned long dirty, unsigned long *pbdi_dirty) |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 270 | { |
H Hartley Sweeten | dcf975d | 2009-06-16 15:31:44 -0700 | [diff] [blame] | 271 | unsigned long avail_dirty; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 272 | |
H Hartley Sweeten | dcf975d | 2009-06-16 15:31:44 -0700 | [diff] [blame] | 273 | avail_dirty = global_page_state(NR_FILE_DIRTY) + |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 274 | global_page_state(NR_WRITEBACK) + |
Miklos Szeredi | fc3ba69 | 2008-04-30 00:54:38 -0700 | [diff] [blame] | 275 | global_page_state(NR_UNSTABLE_NFS) + |
H Hartley Sweeten | dcf975d | 2009-06-16 15:31:44 -0700 | [diff] [blame] | 276 | global_page_state(NR_WRITEBACK_TEMP); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 277 | |
H Hartley Sweeten | dcf975d | 2009-06-16 15:31:44 -0700 | [diff] [blame] | 278 | if (avail_dirty < dirty) |
| 279 | avail_dirty = dirty - avail_dirty; |
| 280 | else |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 281 | avail_dirty = 0; |
| 282 | |
| 283 | avail_dirty += bdi_stat(bdi, BDI_RECLAIMABLE) + |
| 284 | bdi_stat(bdi, BDI_WRITEBACK); |
| 285 | |
| 286 | *pbdi_dirty = min(*pbdi_dirty, avail_dirty); |
| 287 | } |
| 288 | |
Peter Zijlstra | 3e26c14 | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 289 | static inline void task_dirties_fraction(struct task_struct *tsk, |
| 290 | long *numerator, long *denominator) |
| 291 | { |
| 292 | prop_fraction_single(&vm_dirties, &tsk->dirties, |
| 293 | numerator, denominator); |
| 294 | } |
| 295 | |
| 296 | /* |
| 297 | * scale the dirty limit |
| 298 | * |
| 299 | * task specific dirty limit: |
| 300 | * |
| 301 | * dirty -= (dirty/8) * p_{t} |
| 302 | */ |
H Hartley Sweeten | dcf975d | 2009-06-16 15:31:44 -0700 | [diff] [blame] | 303 | static void task_dirty_limit(struct task_struct *tsk, unsigned long *pdirty) |
Peter Zijlstra | 3e26c14 | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 304 | { |
| 305 | long numerator, denominator; |
H Hartley Sweeten | dcf975d | 2009-06-16 15:31:44 -0700 | [diff] [blame] | 306 | unsigned long dirty = *pdirty; |
Peter Zijlstra | 3e26c14 | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 307 | u64 inv = dirty >> 3; |
| 308 | |
| 309 | task_dirties_fraction(tsk, &numerator, &denominator); |
| 310 | inv *= numerator; |
| 311 | do_div(inv, denominator); |
| 312 | |
| 313 | dirty -= inv; |
| 314 | if (dirty < *pdirty/2) |
| 315 | dirty = *pdirty/2; |
| 316 | |
| 317 | *pdirty = dirty; |
| 318 | } |
| 319 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 320 | /* |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 321 | * |
| 322 | */ |
| 323 | static DEFINE_SPINLOCK(bdi_lock); |
| 324 | static unsigned int bdi_min_ratio; |
| 325 | |
| 326 | int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) |
| 327 | { |
| 328 | int ret = 0; |
| 329 | unsigned long flags; |
| 330 | |
| 331 | spin_lock_irqsave(&bdi_lock, flags); |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 332 | if (min_ratio > bdi->max_ratio) { |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 333 | ret = -EINVAL; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 334 | } else { |
| 335 | min_ratio -= bdi->min_ratio; |
| 336 | if (bdi_min_ratio + min_ratio < 100) { |
| 337 | bdi_min_ratio += min_ratio; |
| 338 | bdi->min_ratio += min_ratio; |
| 339 | } else { |
| 340 | ret = -EINVAL; |
| 341 | } |
| 342 | } |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 343 | spin_unlock_irqrestore(&bdi_lock, flags); |
| 344 | |
| 345 | return ret; |
| 346 | } |
| 347 | |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 348 | int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) |
| 349 | { |
| 350 | unsigned long flags; |
| 351 | int ret = 0; |
| 352 | |
| 353 | if (max_ratio > 100) |
| 354 | return -EINVAL; |
| 355 | |
| 356 | spin_lock_irqsave(&bdi_lock, flags); |
| 357 | if (bdi->min_ratio > max_ratio) { |
| 358 | ret = -EINVAL; |
| 359 | } else { |
| 360 | bdi->max_ratio = max_ratio; |
| 361 | bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100; |
| 362 | } |
| 363 | spin_unlock_irqrestore(&bdi_lock, flags); |
| 364 | |
| 365 | return ret; |
| 366 | } |
| 367 | EXPORT_SYMBOL(bdi_set_max_ratio); |
| 368 | |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 369 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 370 | * Work out the current dirty-memory clamping and background writeout |
| 371 | * thresholds. |
| 372 | * |
| 373 | * The main aim here is to lower them aggressively if there is a lot of mapped |
| 374 | * memory around. To avoid stressing page reclaim with lots of unreclaimable |
| 375 | * pages. It is better to clamp down on writers than to start swapping, and |
| 376 | * performing lots of scanning. |
| 377 | * |
| 378 | * We only allow 1/2 of the currently-unmapped memory to be dirtied. |
| 379 | * |
| 380 | * We don't permit the clamping level to fall below 5% - that is getting rather |
| 381 | * excessive. |
| 382 | * |
| 383 | * We make sure that the background writeout level is below the adjusted |
| 384 | * clamping level. |
| 385 | */ |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 386 | |
| 387 | static unsigned long highmem_dirtyable_memory(unsigned long total) |
| 388 | { |
| 389 | #ifdef CONFIG_HIGHMEM |
| 390 | int node; |
| 391 | unsigned long x = 0; |
| 392 | |
Lee Schermerhorn | 37b07e4 | 2007-10-16 01:25:39 -0700 | [diff] [blame] | 393 | for_each_node_state(node, N_HIGH_MEMORY) { |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 394 | struct zone *z = |
| 395 | &NODE_DATA(node)->node_zones[ZONE_HIGHMEM]; |
| 396 | |
Rik van Riel | 4f98a2f | 2008-10-18 20:26:32 -0700 | [diff] [blame] | 397 | x += zone_page_state(z, NR_FREE_PAGES) + zone_lru_pages(z); |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 398 | } |
| 399 | /* |
| 400 | * Make sure that the number of highmem pages is never larger |
| 401 | * than the number of the total dirtyable memory. This can only |
| 402 | * occur in very strange VM situations but we want to make sure |
| 403 | * that this does not occur. |
| 404 | */ |
| 405 | return min(x, total); |
| 406 | #else |
| 407 | return 0; |
| 408 | #endif |
| 409 | } |
| 410 | |
Steven Rostedt | 3eefae9 | 2008-05-12 21:21:04 +0200 | [diff] [blame] | 411 | /** |
| 412 | * determine_dirtyable_memory - amount of memory that may be used |
| 413 | * |
| 414 | * Returns the numebr of pages that can currently be freed and used |
| 415 | * by the kernel for direct mappings. |
| 416 | */ |
| 417 | unsigned long determine_dirtyable_memory(void) |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 418 | { |
| 419 | unsigned long x; |
| 420 | |
Rik van Riel | 4f98a2f | 2008-10-18 20:26:32 -0700 | [diff] [blame] | 421 | x = global_page_state(NR_FREE_PAGES) + global_lru_pages(); |
Bron Gondwana | 195cf453 | 2008-02-04 22:29:20 -0800 | [diff] [blame] | 422 | |
| 423 | if (!vm_highmem_is_dirtyable) |
| 424 | x -= highmem_dirtyable_memory(x); |
| 425 | |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 426 | return x + 1; /* Ensure that we never return 0 */ |
| 427 | } |
| 428 | |
Peter Zijlstra | cf0ca9f | 2008-04-30 00:54:32 -0700 | [diff] [blame] | 429 | void |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 430 | get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty, |
| 431 | unsigned long *pbdi_dirty, struct backing_dev_info *bdi) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 432 | { |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 433 | unsigned long background; |
| 434 | unsigned long dirty; |
Christoph Lameter | 1b42446 | 2007-05-06 14:48:59 -0700 | [diff] [blame] | 435 | unsigned long available_memory = determine_dirtyable_memory(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 436 | struct task_struct *tsk; |
| 437 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 438 | if (vm_dirty_bytes) |
| 439 | dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE); |
| 440 | else { |
| 441 | int dirty_ratio; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 442 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 443 | dirty_ratio = vm_dirty_ratio; |
| 444 | if (dirty_ratio < 5) |
| 445 | dirty_ratio = 5; |
| 446 | dirty = (dirty_ratio * available_memory) / 100; |
| 447 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 448 | |
David Rientjes | 2da0299 | 2009-01-06 14:39:31 -0800 | [diff] [blame] | 449 | if (dirty_background_bytes) |
| 450 | background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE); |
| 451 | else |
| 452 | background = (dirty_background_ratio * available_memory) / 100; |
| 453 | |
| 454 | if (background >= dirty) |
| 455 | background = dirty / 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 456 | tsk = current; |
| 457 | if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) { |
| 458 | background += background / 4; |
| 459 | dirty += dirty / 4; |
| 460 | } |
| 461 | *pbackground = background; |
| 462 | *pdirty = dirty; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 463 | |
| 464 | if (bdi) { |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 465 | u64 bdi_dirty; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 466 | long numerator, denominator; |
| 467 | |
| 468 | /* |
| 469 | * Calculate this BDI's share of the dirty ratio. |
| 470 | */ |
| 471 | bdi_writeout_fraction(bdi, &numerator, &denominator); |
| 472 | |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 473 | bdi_dirty = (dirty * (100 - bdi_min_ratio)) / 100; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 474 | bdi_dirty *= numerator; |
| 475 | do_div(bdi_dirty, denominator); |
Peter Zijlstra | 189d3c4 | 2008-04-30 00:54:35 -0700 | [diff] [blame] | 476 | bdi_dirty += (dirty * bdi->min_ratio) / 100; |
Peter Zijlstra | a42dde0 | 2008-04-30 00:54:36 -0700 | [diff] [blame] | 477 | if (bdi_dirty > (dirty * bdi->max_ratio) / 100) |
| 478 | bdi_dirty = dirty * bdi->max_ratio / 100; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 479 | |
| 480 | *pbdi_dirty = bdi_dirty; |
| 481 | clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty); |
Peter Zijlstra | 3e26c14 | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 482 | task_dirty_limit(current, pbdi_dirty); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 483 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 484 | } |
| 485 | |
| 486 | /* |
| 487 | * balance_dirty_pages() must be called by processes which are generating dirty |
| 488 | * data. It looks at the number of dirty pages in the machine and will force |
| 489 | * the caller to perform writeback if the system is over `vm_dirty_ratio'. |
| 490 | * If we're over `background_thresh' then pdflush is woken to perform some |
| 491 | * writeout. |
| 492 | */ |
| 493 | static void balance_dirty_pages(struct address_space *mapping) |
| 494 | { |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 495 | long nr_reclaimable, bdi_nr_reclaimable; |
| 496 | long nr_writeback, bdi_nr_writeback; |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 497 | unsigned long background_thresh; |
| 498 | unsigned long dirty_thresh; |
| 499 | unsigned long bdi_thresh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 500 | unsigned long pages_written = 0; |
| 501 | unsigned long write_chunk = sync_writeback_pages(); |
| 502 | |
| 503 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
| 504 | |
| 505 | for (;;) { |
| 506 | struct writeback_control wbc = { |
| 507 | .bdi = bdi, |
| 508 | .sync_mode = WB_SYNC_NONE, |
| 509 | .older_than_this = NULL, |
| 510 | .nr_to_write = write_chunk, |
OGAWA Hirofumi | 111ebb6 | 2006-06-23 02:03:26 -0700 | [diff] [blame] | 511 | .range_cyclic = 1, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 512 | }; |
| 513 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 514 | get_dirty_limits(&background_thresh, &dirty_thresh, |
| 515 | &bdi_thresh, bdi); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 516 | |
| 517 | nr_reclaimable = global_page_state(NR_FILE_DIRTY) + |
| 518 | global_page_state(NR_UNSTABLE_NFS); |
| 519 | nr_writeback = global_page_state(NR_WRITEBACK); |
| 520 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 521 | bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE); |
| 522 | bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK); |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 523 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 524 | if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh) |
| 525 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 526 | |
Peter Zijlstra | 5fce25a | 2007-11-14 16:59:15 -0800 | [diff] [blame] | 527 | /* |
| 528 | * Throttle it only when the background writeback cannot |
| 529 | * catch-up. This avoids (excessively) small writeouts |
| 530 | * when the bdi limits are ramping up. |
| 531 | */ |
| 532 | if (nr_reclaimable + nr_writeback < |
| 533 | (background_thresh + dirty_thresh) / 2) |
| 534 | break; |
| 535 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 536 | if (!bdi->dirty_exceeded) |
| 537 | bdi->dirty_exceeded = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 538 | |
| 539 | /* Note: nr_reclaimable denotes nr_dirty + nr_unstable. |
| 540 | * Unstable writes are a feature of certain networked |
| 541 | * filesystems (i.e. NFS) in which data may have been |
| 542 | * written to the server's write cache, but has not yet |
| 543 | * been flushed to permanent storage. |
Richard Kennedy | d7831a0 | 2009-06-30 11:41:35 -0700 | [diff] [blame] | 544 | * Only move pages to writeback if this bdi is over its |
| 545 | * threshold otherwise wait until the disk writes catch |
| 546 | * up. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 547 | */ |
Richard Kennedy | d7831a0 | 2009-06-30 11:41:35 -0700 | [diff] [blame] | 548 | if (bdi_nr_reclaimable > bdi_thresh) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 549 | writeback_inodes(&wbc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 550 | pages_written += write_chunk - wbc.nr_to_write; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 551 | get_dirty_limits(&background_thresh, &dirty_thresh, |
| 552 | &bdi_thresh, bdi); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 553 | } |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 554 | |
| 555 | /* |
| 556 | * In order to avoid the stacked BDI deadlock we need |
| 557 | * to ensure we accurately count the 'dirty' pages when |
| 558 | * the threshold is low. |
| 559 | * |
| 560 | * Otherwise it would be possible to get thresh+n pages |
| 561 | * reported dirty, even though there are thresh-m pages |
| 562 | * actually dirty; with m+n sitting in the percpu |
| 563 | * deltas. |
| 564 | */ |
| 565 | if (bdi_thresh < 2*bdi_stat_error(bdi)) { |
| 566 | bdi_nr_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE); |
| 567 | bdi_nr_writeback = bdi_stat_sum(bdi, BDI_WRITEBACK); |
| 568 | } else if (bdi_nr_reclaimable) { |
| 569 | bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE); |
| 570 | bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK); |
| 571 | } |
| 572 | |
| 573 | if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh) |
| 574 | break; |
| 575 | if (pages_written >= write_chunk) |
| 576 | break; /* We've done our duty */ |
| 577 | |
Jens Axboe | 8aa7e84 | 2009-07-09 14:52:32 +0200 | [diff] [blame] | 578 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 579 | } |
| 580 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 581 | if (bdi_nr_reclaimable + bdi_nr_writeback < bdi_thresh && |
| 582 | bdi->dirty_exceeded) |
| 583 | bdi->dirty_exceeded = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 584 | |
| 585 | if (writeback_in_progress(bdi)) |
| 586 | return; /* pdflush is already working this queue */ |
| 587 | |
| 588 | /* |
| 589 | * In laptop mode, we wait until hitting the higher threshold before |
| 590 | * starting background writeout, and then write out all the way down |
| 591 | * to the lower threshold. So slow writers cause minimal disk activity. |
| 592 | * |
| 593 | * In normal mode, we start background writeout at the lower |
| 594 | * background_thresh, to keep the amount of dirty memory low. |
| 595 | */ |
| 596 | if ((laptop_mode && pages_written) || |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 597 | (!laptop_mode && (global_page_state(NR_FILE_DIRTY) |
| 598 | + global_page_state(NR_UNSTABLE_NFS) |
| 599 | > background_thresh))) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 600 | pdflush_operation(background_writeout, 0); |
| 601 | } |
| 602 | |
Peter Zijlstra | a200ee1 | 2007-10-08 18:54:37 +0200 | [diff] [blame] | 603 | void set_page_dirty_balance(struct page *page, int page_mkwrite) |
Peter Zijlstra | edc79b2 | 2006-09-25 23:30:58 -0700 | [diff] [blame] | 604 | { |
Peter Zijlstra | a200ee1 | 2007-10-08 18:54:37 +0200 | [diff] [blame] | 605 | if (set_page_dirty(page) || page_mkwrite) { |
Peter Zijlstra | edc79b2 | 2006-09-25 23:30:58 -0700 | [diff] [blame] | 606 | struct address_space *mapping = page_mapping(page); |
| 607 | |
| 608 | if (mapping) |
| 609 | balance_dirty_pages_ratelimited(mapping); |
| 610 | } |
| 611 | } |
| 612 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 613 | /** |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 614 | * balance_dirty_pages_ratelimited_nr - balance dirty memory state |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 615 | * @mapping: address_space which was dirtied |
Martin Waitz | a580290 | 2006-04-02 13:59:55 +0200 | [diff] [blame] | 616 | * @nr_pages_dirtied: number of pages which the caller has just dirtied |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 617 | * |
| 618 | * Processes which are dirtying memory should call in here once for each page |
| 619 | * which was newly dirtied. The function will periodically check the system's |
| 620 | * dirty state and will initiate writeback if needed. |
| 621 | * |
| 622 | * On really big machines, get_writeback_state is expensive, so try to avoid |
| 623 | * calling it too often (ratelimiting). But once we're over the dirty memory |
| 624 | * limit we decrease the ratelimiting by a lot, to prevent individual processes |
| 625 | * from overshooting the limit by (ratelimit_pages) each. |
| 626 | */ |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 627 | void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, |
| 628 | unsigned long nr_pages_dirtied) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 629 | { |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 630 | static DEFINE_PER_CPU(unsigned long, ratelimits) = 0; |
| 631 | unsigned long ratelimit; |
| 632 | unsigned long *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 633 | |
| 634 | ratelimit = ratelimit_pages; |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 635 | if (mapping->backing_dev_info->dirty_exceeded) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 636 | ratelimit = 8; |
| 637 | |
| 638 | /* |
| 639 | * Check the rate limiting. Also, we do not want to throttle real-time |
| 640 | * tasks in balance_dirty_pages(). Period. |
| 641 | */ |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 642 | preempt_disable(); |
| 643 | p = &__get_cpu_var(ratelimits); |
| 644 | *p += nr_pages_dirtied; |
| 645 | if (unlikely(*p >= ratelimit)) { |
| 646 | *p = 0; |
| 647 | preempt_enable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 648 | balance_dirty_pages(mapping); |
| 649 | return; |
| 650 | } |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 651 | preempt_enable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 652 | } |
Andrew Morton | fa5a734 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 653 | EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 654 | |
Andrew Morton | 232ea4d | 2007-02-28 20:13:21 -0800 | [diff] [blame] | 655 | void throttle_vm_writeout(gfp_t gfp_mask) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 656 | { |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 657 | unsigned long background_thresh; |
| 658 | unsigned long dirty_thresh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 659 | |
| 660 | for ( ; ; ) { |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 661 | get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 662 | |
| 663 | /* |
| 664 | * Boost the allowable dirty threshold a bit for page |
| 665 | * allocators so they don't get DoS'ed by heavy writers |
| 666 | */ |
| 667 | dirty_thresh += dirty_thresh / 10; /* wheeee... */ |
| 668 | |
Christoph Lameter | c24f21b | 2006-06-30 01:55:42 -0700 | [diff] [blame] | 669 | if (global_page_state(NR_UNSTABLE_NFS) + |
| 670 | global_page_state(NR_WRITEBACK) <= dirty_thresh) |
| 671 | break; |
Jens Axboe | 8aa7e84 | 2009-07-09 14:52:32 +0200 | [diff] [blame] | 672 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
Fengguang Wu | 369f238 | 2007-10-16 23:30:45 -0700 | [diff] [blame] | 673 | |
| 674 | /* |
| 675 | * The caller might hold locks which can prevent IO completion |
| 676 | * or progress in the filesystem. So we cannot just sit here |
| 677 | * waiting for IO to complete. |
| 678 | */ |
| 679 | if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) |
| 680 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 681 | } |
| 682 | } |
| 683 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 684 | /* |
| 685 | * writeback at least _min_pages, and keep writing until the amount of dirty |
| 686 | * memory is less than the background threshold, or until we're all clean. |
| 687 | */ |
| 688 | static void background_writeout(unsigned long _min_pages) |
| 689 | { |
| 690 | long min_pages = _min_pages; |
| 691 | struct writeback_control wbc = { |
| 692 | .bdi = NULL, |
| 693 | .sync_mode = WB_SYNC_NONE, |
| 694 | .older_than_this = NULL, |
| 695 | .nr_to_write = 0, |
| 696 | .nonblocking = 1, |
OGAWA Hirofumi | 111ebb6 | 2006-06-23 02:03:26 -0700 | [diff] [blame] | 697 | .range_cyclic = 1, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 698 | }; |
| 699 | |
| 700 | for ( ; ; ) { |
David Rientjes | 364aeb2 | 2009-01-06 14:39:29 -0800 | [diff] [blame] | 701 | unsigned long background_thresh; |
| 702 | unsigned long dirty_thresh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 703 | |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 704 | get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); |
Christoph Lameter | c24f21b | 2006-06-30 01:55:42 -0700 | [diff] [blame] | 705 | if (global_page_state(NR_FILE_DIRTY) + |
| 706 | global_page_state(NR_UNSTABLE_NFS) < background_thresh |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 707 | && min_pages <= 0) |
| 708 | break; |
Fengguang Wu | 8bc3be2 | 2008-02-04 22:29:36 -0800 | [diff] [blame] | 709 | wbc.more_io = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 710 | wbc.encountered_congestion = 0; |
| 711 | wbc.nr_to_write = MAX_WRITEBACK_PAGES; |
| 712 | wbc.pages_skipped = 0; |
| 713 | writeback_inodes(&wbc); |
| 714 | min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
| 715 | if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) { |
| 716 | /* Wrote less than expected */ |
Fengguang Wu | 8bc3be2 | 2008-02-04 22:29:36 -0800 | [diff] [blame] | 717 | if (wbc.encountered_congestion || wbc.more_io) |
Jens Axboe | 8aa7e84 | 2009-07-09 14:52:32 +0200 | [diff] [blame] | 718 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
Fengguang Wu | 8bc3be2 | 2008-02-04 22:29:36 -0800 | [diff] [blame] | 719 | else |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 720 | break; |
| 721 | } |
| 722 | } |
| 723 | } |
| 724 | |
| 725 | /* |
| 726 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
| 727 | * the whole world. Returns 0 if a pdflush thread was dispatched. Returns |
| 728 | * -1 if all pdflush threads were busy. |
| 729 | */ |
Pekka J Enberg | 687a21c | 2005-06-28 20:44:55 -0700 | [diff] [blame] | 730 | int wakeup_pdflush(long nr_pages) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 731 | { |
Christoph Lameter | c24f21b | 2006-06-30 01:55:42 -0700 | [diff] [blame] | 732 | if (nr_pages == 0) |
| 733 | nr_pages = global_page_state(NR_FILE_DIRTY) + |
| 734 | global_page_state(NR_UNSTABLE_NFS); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 735 | return pdflush_operation(background_writeout, nr_pages); |
| 736 | } |
| 737 | |
| 738 | static void wb_timer_fn(unsigned long unused); |
| 739 | static void laptop_timer_fn(unsigned long unused); |
| 740 | |
Ingo Molnar | 8d06afa | 2005-09-09 13:10:40 -0700 | [diff] [blame] | 741 | static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0); |
| 742 | static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 743 | |
| 744 | /* |
| 745 | * Periodic writeback of "old" data. |
| 746 | * |
| 747 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
| 748 | * dirtying-time in the inode's address_space. So this periodic writeback code |
| 749 | * just walks the superblock inode list, writing back any inodes which are |
| 750 | * older than a specific point in time. |
| 751 | * |
Bart Samwel | f6ef943 | 2006-03-24 03:15:48 -0800 | [diff] [blame] | 752 | * Try to run once per dirty_writeback_interval. But if a writeback event |
| 753 | * takes longer than a dirty_writeback_interval interval, then leave a |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 754 | * one-second gap. |
| 755 | * |
| 756 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
| 757 | * all dirty pages if they are all attached to "old" mappings. |
| 758 | */ |
| 759 | static void wb_kupdate(unsigned long arg) |
| 760 | { |
| 761 | unsigned long oldest_jif; |
| 762 | unsigned long start_jif; |
| 763 | unsigned long next_jif; |
| 764 | long nr_to_write; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 765 | struct writeback_control wbc = { |
| 766 | .bdi = NULL, |
| 767 | .sync_mode = WB_SYNC_NONE, |
| 768 | .older_than_this = &oldest_jif, |
| 769 | .nr_to_write = 0, |
| 770 | .nonblocking = 1, |
| 771 | .for_kupdate = 1, |
OGAWA Hirofumi | 111ebb6 | 2006-06-23 02:03:26 -0700 | [diff] [blame] | 772 | .range_cyclic = 1, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 773 | }; |
| 774 | |
| 775 | sync_supers(); |
| 776 | |
Toshiyuki Okajima | 22ef37e | 2009-05-16 22:56:28 -0700 | [diff] [blame] | 777 | oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 778 | start_jif = jiffies; |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 779 | next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10); |
Christoph Lameter | c24f21b | 2006-06-30 01:55:42 -0700 | [diff] [blame] | 780 | nr_to_write = global_page_state(NR_FILE_DIRTY) + |
| 781 | global_page_state(NR_UNSTABLE_NFS) + |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 782 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); |
| 783 | while (nr_to_write > 0) { |
Fengguang Wu | 8bc3be2 | 2008-02-04 22:29:36 -0800 | [diff] [blame] | 784 | wbc.more_io = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 785 | wbc.encountered_congestion = 0; |
| 786 | wbc.nr_to_write = MAX_WRITEBACK_PAGES; |
| 787 | writeback_inodes(&wbc); |
| 788 | if (wbc.nr_to_write > 0) { |
Fengguang Wu | 8bc3be2 | 2008-02-04 22:29:36 -0800 | [diff] [blame] | 789 | if (wbc.encountered_congestion || wbc.more_io) |
Jens Axboe | 8aa7e84 | 2009-07-09 14:52:32 +0200 | [diff] [blame] | 790 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 791 | else |
| 792 | break; /* All the old data is written */ |
| 793 | } |
| 794 | nr_to_write -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
| 795 | } |
| 796 | if (time_before(next_jif, jiffies + HZ)) |
| 797 | next_jif = jiffies + HZ; |
Bart Samwel | f6ef943 | 2006-03-24 03:15:48 -0800 | [diff] [blame] | 798 | if (dirty_writeback_interval) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 799 | mod_timer(&wb_timer, next_jif); |
| 800 | } |
| 801 | |
| 802 | /* |
| 803 | * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs |
| 804 | */ |
| 805 | int dirty_writeback_centisecs_handler(ctl_table *table, int write, |
Andrew Morton | 3e733f0 | 2007-07-15 23:41:05 -0700 | [diff] [blame] | 806 | struct file *file, void __user *buffer, size_t *length, loff_t *ppos) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 807 | { |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 808 | proc_dointvec(table, write, file, buffer, length, ppos); |
Andrew Morton | 3e733f0 | 2007-07-15 23:41:05 -0700 | [diff] [blame] | 809 | if (dirty_writeback_interval) |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 810 | mod_timer(&wb_timer, jiffies + |
| 811 | msecs_to_jiffies(dirty_writeback_interval * 10)); |
Andrew Morton | 3e733f0 | 2007-07-15 23:41:05 -0700 | [diff] [blame] | 812 | else |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 813 | del_timer(&wb_timer); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 814 | return 0; |
| 815 | } |
| 816 | |
| 817 | static void wb_timer_fn(unsigned long unused) |
| 818 | { |
| 819 | if (pdflush_operation(wb_kupdate, 0) < 0) |
| 820 | mod_timer(&wb_timer, jiffies + HZ); /* delay 1 second */ |
| 821 | } |
| 822 | |
| 823 | static void laptop_flush(unsigned long unused) |
| 824 | { |
| 825 | sys_sync(); |
| 826 | } |
| 827 | |
| 828 | static void laptop_timer_fn(unsigned long unused) |
| 829 | { |
| 830 | pdflush_operation(laptop_flush, 0); |
| 831 | } |
| 832 | |
| 833 | /* |
| 834 | * We've spun up the disk and we're in laptop mode: schedule writeback |
| 835 | * of all dirty data a few seconds from now. If the flush is already scheduled |
| 836 | * then push it back - the user is still using the disk. |
| 837 | */ |
| 838 | void laptop_io_completion(void) |
| 839 | { |
Bart Samwel | ed5b43f | 2006-03-24 03:15:49 -0800 | [diff] [blame] | 840 | mod_timer(&laptop_mode_wb_timer, jiffies + laptop_mode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 841 | } |
| 842 | |
| 843 | /* |
| 844 | * We're in laptop mode and we've just synced. The sync's writes will have |
| 845 | * caused another writeback to be scheduled by laptop_io_completion. |
| 846 | * Nothing needs to be written back anymore, so we unschedule the writeback. |
| 847 | */ |
| 848 | void laptop_sync_completion(void) |
| 849 | { |
| 850 | del_timer(&laptop_mode_wb_timer); |
| 851 | } |
| 852 | |
| 853 | /* |
| 854 | * If ratelimit_pages is too high then we can get into dirty-data overload |
| 855 | * if a large number of processes all perform writes at the same time. |
| 856 | * If it is too low then SMP machines will call the (expensive) |
| 857 | * get_writeback_state too often. |
| 858 | * |
| 859 | * Here we set ratelimit_pages to a level which ensures that when all CPUs are |
| 860 | * dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory |
| 861 | * thresholds before writeback cuts in. |
| 862 | * |
| 863 | * But the limit should not be set too high. Because it also controls the |
| 864 | * amount of memory which the balance_dirty_pages() caller has to write back. |
| 865 | * If this is too large then the caller will block on the IO queue all the |
| 866 | * time. So limit it to four megabytes - the balance_dirty_pages() caller |
| 867 | * will write six megabyte chunks, max. |
| 868 | */ |
| 869 | |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 870 | void writeback_set_ratelimit(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 871 | { |
Chandra Seetharaman | 40c99aa | 2006-09-29 02:01:24 -0700 | [diff] [blame] | 872 | ratelimit_pages = vm_total_pages / (num_online_cpus() * 32); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 873 | if (ratelimit_pages < 16) |
| 874 | ratelimit_pages = 16; |
| 875 | if (ratelimit_pages * PAGE_CACHE_SIZE > 4096 * 1024) |
| 876 | ratelimit_pages = (4096 * 1024) / PAGE_CACHE_SIZE; |
| 877 | } |
| 878 | |
Chandra Seetharaman | 26c2143 | 2006-06-27 02:54:10 -0700 | [diff] [blame] | 879 | static int __cpuinit |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 880 | ratelimit_handler(struct notifier_block *self, unsigned long u, void *v) |
| 881 | { |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 882 | writeback_set_ratelimit(); |
Paul E. McKenney | aa0f030 | 2007-02-10 01:46:37 -0800 | [diff] [blame] | 883 | return NOTIFY_DONE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 884 | } |
| 885 | |
Chandra Seetharaman | 74b85f3 | 2006-06-27 02:54:09 -0700 | [diff] [blame] | 886 | static struct notifier_block __cpuinitdata ratelimit_nb = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 887 | .notifier_call = ratelimit_handler, |
| 888 | .next = NULL, |
| 889 | }; |
| 890 | |
| 891 | /* |
Linus Torvalds | dc6e29d | 2007-01-29 16:37:38 -0800 | [diff] [blame] | 892 | * Called early on to tune the page writeback dirty limits. |
| 893 | * |
| 894 | * We used to scale dirty pages according to how total memory |
| 895 | * related to pages that could be allocated for buffers (by |
| 896 | * comparing nr_free_buffer_pages() to vm_total_pages. |
| 897 | * |
| 898 | * However, that was when we used "dirty_ratio" to scale with |
| 899 | * all memory, and we don't do that any more. "dirty_ratio" |
| 900 | * is now applied to total non-HIGHPAGE memory (by subtracting |
| 901 | * totalhigh_pages from vm_total_pages), and as such we can't |
| 902 | * get into the old insane situation any more where we had |
| 903 | * large amounts of dirty pages compared to a small amount of |
| 904 | * non-HIGHMEM memory. |
| 905 | * |
| 906 | * But we might still want to scale the dirty_ratio by how |
| 907 | * much memory the box has.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 908 | */ |
| 909 | void __init page_writeback_init(void) |
| 910 | { |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 911 | int shift; |
| 912 | |
Alexey Dobriyan | 704503d | 2009-03-31 15:23:18 -0700 | [diff] [blame] | 913 | mod_timer(&wb_timer, |
| 914 | jiffies + msecs_to_jiffies(dirty_writeback_interval * 10)); |
Chandra Seetharaman | 2d1d43f | 2006-09-29 02:01:25 -0700 | [diff] [blame] | 915 | writeback_set_ratelimit(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 916 | register_cpu_notifier(&ratelimit_nb); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 917 | |
| 918 | shift = calc_period_shift(); |
| 919 | prop_descriptor_init(&vm_completions, shift); |
Peter Zijlstra | 3e26c14 | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 920 | prop_descriptor_init(&vm_dirties, shift); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 921 | } |
| 922 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 923 | /** |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 924 | * 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] | 925 | * @mapping: address space structure to write |
| 926 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 927 | * @writepage: function called for each page |
| 928 | * @data: data passed to writepage function |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 929 | * |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 930 | * 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] | 931 | * if it's dirty. This is desirable behaviour for memory-cleaning writeback, |
| 932 | * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() |
| 933 | * and msync() need to guarantee that all the data which was dirty at the time |
| 934 | * the call was made get new I/O started against them. If wbc->sync_mode is |
| 935 | * WB_SYNC_ALL then we were called for data integrity and we must wait for |
| 936 | * existing IO to complete. |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 937 | */ |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 938 | int write_cache_pages(struct address_space *mapping, |
| 939 | struct writeback_control *wbc, writepage_t writepage, |
| 940 | void *data) |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 941 | { |
| 942 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
| 943 | int ret = 0; |
| 944 | int done = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 945 | struct pagevec pvec; |
| 946 | int nr_pages; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 947 | pgoff_t uninitialized_var(writeback_index); |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 948 | pgoff_t index; |
| 949 | pgoff_t end; /* Inclusive */ |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 950 | pgoff_t done_index; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 951 | int cycled; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 952 | int range_whole = 0; |
Aneesh Kumar K.V | 17bc6c3 | 2008-10-16 10:09:17 -0400 | [diff] [blame] | 953 | long nr_to_write = wbc->nr_to_write; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 954 | |
| 955 | if (wbc->nonblocking && bdi_write_congested(bdi)) { |
| 956 | wbc->encountered_congestion = 1; |
| 957 | return 0; |
| 958 | } |
| 959 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 960 | pagevec_init(&pvec, 0); |
| 961 | if (wbc->range_cyclic) { |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 962 | writeback_index = mapping->writeback_index; /* prev offset */ |
| 963 | index = writeback_index; |
| 964 | if (index == 0) |
| 965 | cycled = 1; |
| 966 | else |
| 967 | cycled = 0; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 968 | end = -1; |
| 969 | } else { |
| 970 | index = wbc->range_start >> PAGE_CACHE_SHIFT; |
| 971 | end = wbc->range_end >> PAGE_CACHE_SHIFT; |
| 972 | if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) |
| 973 | range_whole = 1; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 974 | cycled = 1; /* ignore range_cyclic tests */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 975 | } |
| 976 | retry: |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 977 | done_index = index; |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 978 | while (!done && (index <= end)) { |
| 979 | int i; |
| 980 | |
| 981 | nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, |
| 982 | PAGECACHE_TAG_DIRTY, |
| 983 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1); |
| 984 | if (nr_pages == 0) |
| 985 | break; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 986 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 987 | for (i = 0; i < nr_pages; i++) { |
| 988 | struct page *page = pvec.pages[i]; |
| 989 | |
Nick Piggin | d5482cd | 2009-01-06 14:39:11 -0800 | [diff] [blame] | 990 | /* |
| 991 | * At this point, the page may be truncated or |
| 992 | * invalidated (changing page->mapping to NULL), or |
| 993 | * even swizzled back from swapper_space to tmpfs file |
| 994 | * mapping. However, page->index will not change |
| 995 | * because we have a reference on the page. |
| 996 | */ |
| 997 | if (page->index > end) { |
| 998 | /* |
| 999 | * can't be range_cyclic (1st pass) because |
| 1000 | * end == -1 in that case. |
| 1001 | */ |
| 1002 | done = 1; |
| 1003 | break; |
| 1004 | } |
| 1005 | |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1006 | done_index = page->index + 1; |
| 1007 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1008 | lock_page(page); |
| 1009 | |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1010 | /* |
| 1011 | * Page truncated or invalidated. We can freely skip it |
| 1012 | * then, even for data integrity operations: the page |
| 1013 | * has disappeared concurrently, so there could be no |
| 1014 | * real expectation of this data interity operation |
| 1015 | * even if there is now a new, dirty page at the same |
| 1016 | * pagecache address. |
| 1017 | */ |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1018 | if (unlikely(page->mapping != mapping)) { |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1019 | continue_unlock: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1020 | unlock_page(page); |
| 1021 | continue; |
| 1022 | } |
| 1023 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 1024 | if (!PageDirty(page)) { |
| 1025 | /* someone wrote it for us */ |
| 1026 | goto continue_unlock; |
| 1027 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1028 | |
Nick Piggin | 515f4a0 | 2009-01-06 14:39:10 -0800 | [diff] [blame] | 1029 | if (PageWriteback(page)) { |
| 1030 | if (wbc->sync_mode != WB_SYNC_NONE) |
| 1031 | wait_on_page_writeback(page); |
| 1032 | else |
| 1033 | goto continue_unlock; |
| 1034 | } |
| 1035 | |
| 1036 | BUG_ON(PageWriteback(page)); |
| 1037 | if (!clear_page_dirty_for_io(page)) |
Nick Piggin | 5a3d5c9 | 2009-01-06 14:39:09 -0800 | [diff] [blame] | 1038 | goto continue_unlock; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1039 | |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1040 | ret = (*writepage)(page, wbc, data); |
Nick Piggin | 0026677 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1041 | if (unlikely(ret)) { |
| 1042 | if (ret == AOP_WRITEPAGE_ACTIVATE) { |
| 1043 | unlock_page(page); |
| 1044 | ret = 0; |
| 1045 | } else { |
| 1046 | /* |
| 1047 | * done_index is set past this page, |
| 1048 | * so media errors will not choke |
| 1049 | * background writeout for the entire |
| 1050 | * file. This has consequences for |
| 1051 | * range_cyclic semantics (ie. it may |
| 1052 | * not be suitable for data integrity |
| 1053 | * writeout). |
| 1054 | */ |
| 1055 | done = 1; |
| 1056 | break; |
| 1057 | } |
| 1058 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1059 | |
Federico Cuello | 89e1219 | 2009-02-11 13:04:39 -0800 | [diff] [blame] | 1060 | if (nr_to_write > 0) { |
Artem Bityutskiy | dcf6a79 | 2009-02-02 18:33:49 +0200 | [diff] [blame] | 1061 | nr_to_write--; |
Federico Cuello | 89e1219 | 2009-02-11 13:04:39 -0800 | [diff] [blame] | 1062 | if (nr_to_write == 0 && |
| 1063 | wbc->sync_mode == WB_SYNC_NONE) { |
| 1064 | /* |
| 1065 | * We stop writing back only if we are |
| 1066 | * not doing integrity sync. In case of |
| 1067 | * integrity sync we have to keep going |
| 1068 | * because someone may be concurrently |
| 1069 | * dirtying pages, and we might have |
| 1070 | * synced a lot of newly appeared dirty |
| 1071 | * pages, but have not synced all of the |
| 1072 | * old dirty pages. |
| 1073 | */ |
| 1074 | done = 1; |
| 1075 | break; |
| 1076 | } |
Nick Piggin | 05fe478 | 2009-01-06 14:39:08 -0800 | [diff] [blame] | 1077 | } |
Artem Bityutskiy | dcf6a79 | 2009-02-02 18:33:49 +0200 | [diff] [blame] | 1078 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1079 | if (wbc->nonblocking && bdi_write_congested(bdi)) { |
| 1080 | wbc->encountered_congestion = 1; |
| 1081 | done = 1; |
Andrew Morton | 82fd1a9 | 2009-01-06 14:39:11 -0800 | [diff] [blame] | 1082 | break; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1083 | } |
| 1084 | } |
| 1085 | pagevec_release(&pvec); |
| 1086 | cond_resched(); |
| 1087 | } |
Nick Piggin | 3a4c680 | 2009-02-12 04:34:23 +0100 | [diff] [blame] | 1088 | if (!cycled && !done) { |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1089 | /* |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1090 | * range_cyclic: |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1091 | * We hit the last page and there is more work to be done: wrap |
| 1092 | * back to the start of the file |
| 1093 | */ |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1094 | cycled = 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1095 | index = 0; |
Nick Piggin | 31a1266 | 2009-01-06 14:39:04 -0800 | [diff] [blame] | 1096 | end = writeback_index - 1; |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1097 | goto retry; |
| 1098 | } |
Aneesh Kumar K.V | 17bc6c3 | 2008-10-16 10:09:17 -0400 | [diff] [blame] | 1099 | if (!wbc->no_nrwrite_index_update) { |
| 1100 | if (wbc->range_cyclic || (range_whole && nr_to_write > 0)) |
Nick Piggin | bd19e01 | 2009-01-06 14:39:06 -0800 | [diff] [blame] | 1101 | mapping->writeback_index = done_index; |
Aneesh Kumar K.V | 17bc6c3 | 2008-10-16 10:09:17 -0400 | [diff] [blame] | 1102 | wbc->nr_to_write = nr_to_write; |
| 1103 | } |
Aneesh Kumar K.V | 06d6cf6 | 2008-07-11 19:27:31 -0400 | [diff] [blame] | 1104 | |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1105 | return ret; |
| 1106 | } |
Miklos Szeredi | 0ea9718 | 2007-05-10 22:22:51 -0700 | [diff] [blame] | 1107 | EXPORT_SYMBOL(write_cache_pages); |
| 1108 | |
| 1109 | /* |
| 1110 | * Function used by generic_writepages to call the real writepage |
| 1111 | * function and set the mapping flags on error |
| 1112 | */ |
| 1113 | static int __writepage(struct page *page, struct writeback_control *wbc, |
| 1114 | void *data) |
| 1115 | { |
| 1116 | struct address_space *mapping = data; |
| 1117 | int ret = mapping->a_ops->writepage(page, wbc); |
| 1118 | mapping_set_error(mapping, ret); |
| 1119 | return ret; |
| 1120 | } |
| 1121 | |
| 1122 | /** |
| 1123 | * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them. |
| 1124 | * @mapping: address space structure to write |
| 1125 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
| 1126 | * |
| 1127 | * This is a library function, which implements the writepages() |
| 1128 | * address_space_operation. |
| 1129 | */ |
| 1130 | int generic_writepages(struct address_space *mapping, |
| 1131 | struct writeback_control *wbc) |
| 1132 | { |
| 1133 | /* deal with chardevs and other special file */ |
| 1134 | if (!mapping->a_ops->writepage) |
| 1135 | return 0; |
| 1136 | |
| 1137 | return write_cache_pages(mapping, wbc, __writepage, mapping); |
| 1138 | } |
David Howells | 811d736 | 2006-08-29 19:06:09 +0100 | [diff] [blame] | 1139 | |
| 1140 | EXPORT_SYMBOL(generic_writepages); |
| 1141 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1142 | int do_writepages(struct address_space *mapping, struct writeback_control *wbc) |
| 1143 | { |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 1144 | int ret; |
| 1145 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1146 | if (wbc->nr_to_write <= 0) |
| 1147 | return 0; |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 1148 | wbc->for_writepages = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1149 | if (mapping->a_ops->writepages) |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 1150 | ret = mapping->a_ops->writepages(mapping, wbc); |
Andrew Morton | 22905f7 | 2005-11-16 15:07:01 -0800 | [diff] [blame] | 1151 | else |
| 1152 | ret = generic_writepages(mapping, wbc); |
| 1153 | wbc->for_writepages = 0; |
| 1154 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1155 | } |
| 1156 | |
| 1157 | /** |
| 1158 | * 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] | 1159 | * @page: the page to write |
| 1160 | * @wait: if true, wait on writeout |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1161 | * |
| 1162 | * The page must be locked by the caller and will be unlocked upon return. |
| 1163 | * |
| 1164 | * write_one_page() returns a negative error code if I/O failed. |
| 1165 | */ |
| 1166 | int write_one_page(struct page *page, int wait) |
| 1167 | { |
| 1168 | struct address_space *mapping = page->mapping; |
| 1169 | int ret = 0; |
| 1170 | struct writeback_control wbc = { |
| 1171 | .sync_mode = WB_SYNC_ALL, |
| 1172 | .nr_to_write = 1, |
| 1173 | }; |
| 1174 | |
| 1175 | BUG_ON(!PageLocked(page)); |
| 1176 | |
| 1177 | if (wait) |
| 1178 | wait_on_page_writeback(page); |
| 1179 | |
| 1180 | if (clear_page_dirty_for_io(page)) { |
| 1181 | page_cache_get(page); |
| 1182 | ret = mapping->a_ops->writepage(page, &wbc); |
| 1183 | if (ret == 0 && wait) { |
| 1184 | wait_on_page_writeback(page); |
| 1185 | if (PageError(page)) |
| 1186 | ret = -EIO; |
| 1187 | } |
| 1188 | page_cache_release(page); |
| 1189 | } else { |
| 1190 | unlock_page(page); |
| 1191 | } |
| 1192 | return ret; |
| 1193 | } |
| 1194 | EXPORT_SYMBOL(write_one_page); |
| 1195 | |
| 1196 | /* |
Ken Chen | 7671932 | 2007-02-10 01:43:15 -0800 | [diff] [blame] | 1197 | * For address_spaces which do not use buffers nor write back. |
| 1198 | */ |
| 1199 | int __set_page_dirty_no_writeback(struct page *page) |
| 1200 | { |
| 1201 | if (!PageDirty(page)) |
| 1202 | SetPageDirty(page); |
| 1203 | return 0; |
| 1204 | } |
| 1205 | |
| 1206 | /* |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 1207 | * Helper function for set_page_dirty family. |
| 1208 | * NOTE: This relies on being atomic wrt interrupts. |
| 1209 | */ |
| 1210 | void account_page_dirtied(struct page *page, struct address_space *mapping) |
| 1211 | { |
| 1212 | if (mapping_cap_account_dirty(mapping)) { |
| 1213 | __inc_zone_page_state(page, NR_FILE_DIRTY); |
| 1214 | __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); |
| 1215 | task_dirty_inc(current); |
| 1216 | task_io_account_write(PAGE_CACHE_SIZE); |
| 1217 | } |
| 1218 | } |
| 1219 | |
| 1220 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1221 | * For address_spaces which do not use buffers. Just tag the page as dirty in |
| 1222 | * its radix tree. |
| 1223 | * |
| 1224 | * This is also used when a single buffer is being dirtied: we want to set the |
| 1225 | * page dirty in that case, but not all the buffers. This is a "bottom-up" |
| 1226 | * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying. |
| 1227 | * |
| 1228 | * Most callers have locked the page, which pins the address_space in memory. |
| 1229 | * But zap_pte_range() does not lock the page, however in that case the |
| 1230 | * mapping is pinned by the vma's ->vm_file reference. |
| 1231 | * |
| 1232 | * We take care to handle the case where the page was truncated from the |
Simon Arlott | 183ff22 | 2007-10-20 01:27:18 +0200 | [diff] [blame] | 1233 | * mapping by re-checking page_mapping() inside tree_lock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1234 | */ |
| 1235 | int __set_page_dirty_nobuffers(struct page *page) |
| 1236 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1237 | if (!TestSetPageDirty(page)) { |
| 1238 | struct address_space *mapping = page_mapping(page); |
| 1239 | struct address_space *mapping2; |
| 1240 | |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1241 | if (!mapping) |
| 1242 | return 1; |
| 1243 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1244 | spin_lock_irq(&mapping->tree_lock); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1245 | mapping2 = page_mapping(page); |
| 1246 | if (mapping2) { /* Race with truncate? */ |
| 1247 | BUG_ON(mapping2 != mapping); |
Nick Piggin | 787d221 | 2007-07-17 04:03:34 -0700 | [diff] [blame] | 1248 | WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page)); |
Edward Shishkin | e3a7cca | 2009-03-31 15:19:39 -0700 | [diff] [blame] | 1249 | account_page_dirtied(page, mapping); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1250 | radix_tree_tag_set(&mapping->page_tree, |
| 1251 | page_index(page), PAGECACHE_TAG_DIRTY); |
| 1252 | } |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1253 | spin_unlock_irq(&mapping->tree_lock); |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1254 | if (mapping->host) { |
| 1255 | /* !PageAnon && !swapper_space */ |
| 1256 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1257 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 1258 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1259 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 1260 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1261 | } |
| 1262 | EXPORT_SYMBOL(__set_page_dirty_nobuffers); |
| 1263 | |
| 1264 | /* |
| 1265 | * When a writepage implementation decides that it doesn't want to write this |
| 1266 | * page for some reason, it should redirty the locked page via |
| 1267 | * redirty_page_for_writepage() and it should then unlock the page and return 0 |
| 1268 | */ |
| 1269 | int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page) |
| 1270 | { |
| 1271 | wbc->pages_skipped++; |
| 1272 | return __set_page_dirty_nobuffers(page); |
| 1273 | } |
| 1274 | EXPORT_SYMBOL(redirty_page_for_writepage); |
| 1275 | |
| 1276 | /* |
| 1277 | * If the mapping doesn't provide a set_page_dirty a_op, then |
| 1278 | * just fall through and assume that it wants buffer_heads. |
| 1279 | */ |
Nick Piggin | 1cf6e7d | 2009-02-18 14:48:18 -0800 | [diff] [blame] | 1280 | int set_page_dirty(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1281 | { |
| 1282 | struct address_space *mapping = page_mapping(page); |
| 1283 | |
| 1284 | if (likely(mapping)) { |
| 1285 | int (*spd)(struct page *) = mapping->a_ops->set_page_dirty; |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 1286 | #ifdef CONFIG_BLOCK |
| 1287 | if (!spd) |
| 1288 | spd = __set_page_dirty_buffers; |
| 1289 | #endif |
| 1290 | return (*spd)(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1291 | } |
Andrew Morton | 4741c9f | 2006-03-24 03:18:11 -0800 | [diff] [blame] | 1292 | if (!PageDirty(page)) { |
| 1293 | if (!TestSetPageDirty(page)) |
| 1294 | return 1; |
| 1295 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1296 | return 0; |
| 1297 | } |
| 1298 | EXPORT_SYMBOL(set_page_dirty); |
| 1299 | |
| 1300 | /* |
| 1301 | * set_page_dirty() is racy if the caller has no reference against |
| 1302 | * page->mapping->host, and if the page is unlocked. This is because another |
| 1303 | * CPU could truncate the page off the mapping and then free the mapping. |
| 1304 | * |
| 1305 | * Usually, the page _is_ locked, or the caller is a user-space process which |
| 1306 | * holds a reference on the inode by having an open file. |
| 1307 | * |
| 1308 | * In other cases, the page should be locked before running set_page_dirty(). |
| 1309 | */ |
| 1310 | int set_page_dirty_lock(struct page *page) |
| 1311 | { |
| 1312 | int ret; |
| 1313 | |
Nick Piggin | db37648 | 2006-09-25 23:31:24 -0700 | [diff] [blame] | 1314 | lock_page_nosync(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1315 | ret = set_page_dirty(page); |
| 1316 | unlock_page(page); |
| 1317 | return ret; |
| 1318 | } |
| 1319 | EXPORT_SYMBOL(set_page_dirty_lock); |
| 1320 | |
| 1321 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1322 | * Clear a page's dirty flag, while caring for dirty memory accounting. |
| 1323 | * Returns true if the page was previously dirty. |
| 1324 | * |
| 1325 | * This is for preparing to put the page under writeout. We leave the page |
| 1326 | * tagged as dirty in the radix tree so that a concurrent write-for-sync |
| 1327 | * can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage |
| 1328 | * implementation will run either set_page_writeback() or set_page_dirty(), |
| 1329 | * at which stage we bring the page's dirty flag and radix-tree dirty tag |
| 1330 | * back into sync. |
| 1331 | * |
| 1332 | * This incoherency between the page's dirty flag and radix-tree tag is |
| 1333 | * unfortunate, but it only exists while the page is locked. |
| 1334 | */ |
| 1335 | int clear_page_dirty_for_io(struct page *page) |
| 1336 | { |
| 1337 | struct address_space *mapping = page_mapping(page); |
| 1338 | |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 1339 | BUG_ON(!PageLocked(page)); |
| 1340 | |
Fengguang Wu | fe3cba1 | 2007-07-19 01:48:07 -0700 | [diff] [blame] | 1341 | ClearPageReclaim(page); |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1342 | if (mapping && mapping_cap_account_dirty(mapping)) { |
| 1343 | /* |
| 1344 | * Yes, Virginia, this is indeed insane. |
| 1345 | * |
| 1346 | * We use this sequence to make sure that |
| 1347 | * (a) we account for dirty stats properly |
| 1348 | * (b) we tell the low-level filesystem to |
| 1349 | * mark the whole page dirty if it was |
| 1350 | * dirty in a pagetable. Only to then |
| 1351 | * (c) clean the page again and return 1 to |
| 1352 | * cause the writeback. |
| 1353 | * |
| 1354 | * This way we avoid all nasty races with the |
| 1355 | * dirty bit in multiple places and clearing |
| 1356 | * them concurrently from different threads. |
| 1357 | * |
| 1358 | * Note! Normally the "set_page_dirty(page)" |
| 1359 | * has no effect on the actual dirty bit - since |
| 1360 | * that will already usually be set. But we |
| 1361 | * need the side effects, and it can help us |
| 1362 | * avoid races. |
| 1363 | * |
| 1364 | * We basically use the page "master dirty bit" |
| 1365 | * as a serialization point for all the different |
| 1366 | * threads doing their things. |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1367 | */ |
| 1368 | if (page_mkclean(page)) |
| 1369 | set_page_dirty(page); |
Nick Piggin | 7935289 | 2007-07-19 01:47:22 -0700 | [diff] [blame] | 1370 | /* |
| 1371 | * We carefully synchronise fault handlers against |
| 1372 | * installing a dirty pte and marking the page dirty |
| 1373 | * at this point. We do this by having them hold the |
| 1374 | * page lock at some point after installing their |
| 1375 | * pte, but before marking the page dirty. |
| 1376 | * Pages are always locked coming in here, so we get |
| 1377 | * the desired exclusion. See mm/memory.c:do_wp_page() |
| 1378 | * for more comments. |
| 1379 | */ |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1380 | if (TestClearPageDirty(page)) { |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 1381 | dec_zone_page_state(page, NR_FILE_DIRTY); |
Peter Zijlstra | c9e51e4 | 2007-10-16 23:25:47 -0700 | [diff] [blame] | 1382 | dec_bdi_stat(mapping->backing_dev_info, |
| 1383 | BDI_RECLAIMABLE); |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1384 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1385 | } |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1386 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1387 | } |
Linus Torvalds | 7658cc2 | 2006-12-29 10:00:58 -0800 | [diff] [blame] | 1388 | return TestClearPageDirty(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1389 | } |
Hans Reiser | 58bb01a | 2005-11-18 01:10:53 -0800 | [diff] [blame] | 1390 | EXPORT_SYMBOL(clear_page_dirty_for_io); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1391 | |
| 1392 | int test_clear_page_writeback(struct page *page) |
| 1393 | { |
| 1394 | struct address_space *mapping = page_mapping(page); |
| 1395 | int ret; |
| 1396 | |
| 1397 | if (mapping) { |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1398 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1399 | unsigned long flags; |
| 1400 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1401 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1402 | ret = TestClearPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1403 | if (ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1404 | radix_tree_tag_clear(&mapping->page_tree, |
| 1405 | page_index(page), |
| 1406 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 1407 | if (bdi_cap_account_writeback(bdi)) { |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1408 | __dec_bdi_stat(bdi, BDI_WRITEBACK); |
Peter Zijlstra | 04fbfdc | 2007-10-16 23:25:50 -0700 | [diff] [blame] | 1409 | __bdi_writeout_inc(bdi); |
| 1410 | } |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1411 | } |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1412 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1413 | } else { |
| 1414 | ret = TestClearPageWriteback(page); |
| 1415 | } |
Andrew Morton | d688abf | 2007-07-19 01:49:17 -0700 | [diff] [blame] | 1416 | if (ret) |
| 1417 | dec_zone_page_state(page, NR_WRITEBACK); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1418 | return ret; |
| 1419 | } |
| 1420 | |
| 1421 | int test_set_page_writeback(struct page *page) |
| 1422 | { |
| 1423 | struct address_space *mapping = page_mapping(page); |
| 1424 | int ret; |
| 1425 | |
| 1426 | if (mapping) { |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1427 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1428 | unsigned long flags; |
| 1429 | |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1430 | spin_lock_irqsave(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1431 | ret = TestSetPageWriteback(page); |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1432 | if (!ret) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1433 | radix_tree_tag_set(&mapping->page_tree, |
| 1434 | page_index(page), |
| 1435 | PAGECACHE_TAG_WRITEBACK); |
Miklos Szeredi | e4ad08f | 2008-04-30 00:54:37 -0700 | [diff] [blame] | 1436 | if (bdi_cap_account_writeback(bdi)) |
Peter Zijlstra | 69cb51d | 2007-10-16 23:25:48 -0700 | [diff] [blame] | 1437 | __inc_bdi_stat(bdi, BDI_WRITEBACK); |
| 1438 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1439 | if (!PageDirty(page)) |
| 1440 | radix_tree_tag_clear(&mapping->page_tree, |
| 1441 | page_index(page), |
| 1442 | PAGECACHE_TAG_DIRTY); |
Nick Piggin | 19fd623 | 2008-07-25 19:45:32 -0700 | [diff] [blame] | 1443 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1444 | } else { |
| 1445 | ret = TestSetPageWriteback(page); |
| 1446 | } |
Andrew Morton | d688abf | 2007-07-19 01:49:17 -0700 | [diff] [blame] | 1447 | if (!ret) |
| 1448 | inc_zone_page_state(page, NR_WRITEBACK); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1449 | return ret; |
| 1450 | |
| 1451 | } |
| 1452 | EXPORT_SYMBOL(test_set_page_writeback); |
| 1453 | |
| 1454 | /* |
Nick Piggin | 0012818 | 2007-10-16 01:24:40 -0700 | [diff] [blame] | 1455 | * 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] | 1456 | * passed tag. |
| 1457 | */ |
| 1458 | int mapping_tagged(struct address_space *mapping, int tag) |
| 1459 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1460 | int ret; |
Nick Piggin | 0012818 | 2007-10-16 01:24:40 -0700 | [diff] [blame] | 1461 | rcu_read_lock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1462 | ret = radix_tree_tagged(&mapping->page_tree, tag); |
Nick Piggin | 0012818 | 2007-10-16 01:24:40 -0700 | [diff] [blame] | 1463 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1464 | return ret; |
| 1465 | } |
| 1466 | EXPORT_SYMBOL(mapping_tagged); |