4 * Copyright (C) 2002, Linus Torvalds.
5 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
7 * Contains functions related to writing back dirty pages at the
10 * 10Apr2002 Andrew Morton
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/spinlock.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>
25 #include <linux/task_io_accounting_ops.h>
26 #include <linux/blkdev.h>
27 #include <linux/mpage.h>
28 #include <linux/rmap.h>
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>
35 #include <linux/buffer_head.h>
36 #include <linux/pagevec.h>
37 #include <trace/events/writeback.h>
40 * Sleep at most 200ms at a time in balance_dirty_pages().
42 #define MAX_PAUSE max(HZ/5, 1)
45 * Estimate write bandwidth at 200ms intervals.
47 #define BANDWIDTH_INTERVAL max(HZ/5, 1)
50 * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited
51 * will look to see if it needs to force writeback or throttling.
53 static long ratelimit_pages
= 32;
56 * When balance_dirty_pages decides that the caller needs to perform some
57 * non-background writeback, this is how many pages it will attempt to write.
58 * It should be somewhat larger than dirtied pages to ensure that reasonably
59 * large amounts of I/O are submitted.
61 static inline long sync_writeback_pages(unsigned long dirtied
)
63 if (dirtied
< ratelimit_pages
)
64 dirtied
= ratelimit_pages
;
66 return dirtied
+ dirtied
/ 2;
69 /* The following parameters are exported via /proc/sys/vm */
72 * Start background writeback (via writeback threads) at this percentage
74 int dirty_background_ratio
= 10;
77 * dirty_background_bytes starts at 0 (disabled) so that it is a function of
78 * dirty_background_ratio * the amount of dirtyable memory
80 unsigned long dirty_background_bytes
;
83 * free highmem will not be subtracted from the total free memory
84 * for calculating free ratios if vm_highmem_is_dirtyable is true
86 int vm_highmem_is_dirtyable
;
89 * The generator of dirty data starts writeback at this percentage
91 int vm_dirty_ratio
= 20;
94 * vm_dirty_bytes starts at 0 (disabled) so that it is a function of
95 * vm_dirty_ratio * the amount of dirtyable memory
97 unsigned long vm_dirty_bytes
;
100 * The interval between `kupdate'-style writebacks
102 unsigned int dirty_writeback_interval
= 5 * 100; /* centiseconds */
105 * The longest time for which data is allowed to remain dirty
107 unsigned int dirty_expire_interval
= 30 * 100; /* centiseconds */
110 * Flag that makes the machine dump writes/reads and block dirtyings.
115 * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies:
116 * a full sync is triggered after this time elapses without any disk activity.
120 EXPORT_SYMBOL(laptop_mode
);
122 /* End of sysctl-exported parameters */
124 unsigned long global_dirty_limit
;
127 * Scale the writeback cache size proportional to the relative writeout speeds.
129 * We do this by keeping a floating proportion between BDIs, based on page
130 * writeback completions [end_page_writeback()]. Those devices that write out
131 * pages fastest will get the larger share, while the slower will get a smaller
134 * We use page writeout completions because we are interested in getting rid of
135 * dirty pages. Having them written out is the primary goal.
137 * We introduce a concept of time, a period over which we measure these events,
138 * because demand can/will vary over time. The length of this period itself is
139 * measured in page writeback completions.
142 static struct prop_descriptor vm_completions
;
143 static struct prop_descriptor vm_dirties
;
146 * couple the period to the dirty_ratio:
148 * period/2 ~ roundup_pow_of_two(dirty limit)
150 static int calc_period_shift(void)
152 unsigned long dirty_total
;
155 dirty_total
= vm_dirty_bytes
/ PAGE_SIZE
;
157 dirty_total
= (vm_dirty_ratio
* determine_dirtyable_memory()) /
159 return 2 + ilog2(dirty_total
- 1);
163 * update the period when the dirty threshold changes.
165 static void update_completion_period(void)
167 int shift
= calc_period_shift();
168 prop_change_shift(&vm_completions
, shift
);
169 prop_change_shift(&vm_dirties
, shift
);
172 int dirty_background_ratio_handler(struct ctl_table
*table
, int write
,
173 void __user
*buffer
, size_t *lenp
,
178 ret
= proc_dointvec_minmax(table
, write
, buffer
, lenp
, ppos
);
179 if (ret
== 0 && write
)
180 dirty_background_bytes
= 0;
184 int dirty_background_bytes_handler(struct ctl_table
*table
, int write
,
185 void __user
*buffer
, size_t *lenp
,
190 ret
= proc_doulongvec_minmax(table
, write
, buffer
, lenp
, ppos
);
191 if (ret
== 0 && write
)
192 dirty_background_ratio
= 0;
196 int dirty_ratio_handler(struct ctl_table
*table
, int write
,
197 void __user
*buffer
, size_t *lenp
,
200 int old_ratio
= vm_dirty_ratio
;
203 ret
= proc_dointvec_minmax(table
, write
, buffer
, lenp
, ppos
);
204 if (ret
== 0 && write
&& vm_dirty_ratio
!= old_ratio
) {
205 update_completion_period();
212 int dirty_bytes_handler(struct ctl_table
*table
, int write
,
213 void __user
*buffer
, size_t *lenp
,
216 unsigned long old_bytes
= vm_dirty_bytes
;
219 ret
= proc_doulongvec_minmax(table
, write
, buffer
, lenp
, ppos
);
220 if (ret
== 0 && write
&& vm_dirty_bytes
!= old_bytes
) {
221 update_completion_period();
228 * Increment the BDI's writeout completion count and the global writeout
229 * completion count. Called from test_clear_page_writeback().
231 static inline void __bdi_writeout_inc(struct backing_dev_info
*bdi
)
233 __inc_bdi_stat(bdi
, BDI_WRITTEN
);
234 __prop_inc_percpu_max(&vm_completions
, &bdi
->completions
,
238 void bdi_writeout_inc(struct backing_dev_info
*bdi
)
242 local_irq_save(flags
);
243 __bdi_writeout_inc(bdi
);
244 local_irq_restore(flags
);
246 EXPORT_SYMBOL_GPL(bdi_writeout_inc
);
248 void task_dirty_inc(struct task_struct
*tsk
)
250 prop_inc_single(&vm_dirties
, &tsk
->dirties
);
254 * Obtain an accurate fraction of the BDI's portion.
256 static void bdi_writeout_fraction(struct backing_dev_info
*bdi
,
257 long *numerator
, long *denominator
)
259 prop_fraction_percpu(&vm_completions
, &bdi
->completions
,
260 numerator
, denominator
);
263 static inline void task_dirties_fraction(struct task_struct
*tsk
,
264 long *numerator
, long *denominator
)
266 prop_fraction_single(&vm_dirties
, &tsk
->dirties
,
267 numerator
, denominator
);
271 * task_dirty_limit - scale down dirty throttling threshold for one task
273 * task specific dirty limit:
275 * dirty -= (dirty/8) * p_{t}
277 * To protect light/slow dirtying tasks from heavier/fast ones, we start
278 * throttling individual tasks before reaching the bdi dirty limit.
279 * Relatively low thresholds will be allocated to heavy dirtiers. So when
280 * dirty pages grow large, heavy dirtiers will be throttled first, which will
281 * effectively curb the growth of dirty pages. Light dirtiers with high enough
282 * dirty threshold may never get throttled.
284 #define TASK_LIMIT_FRACTION 8
285 static unsigned long task_dirty_limit(struct task_struct
*tsk
,
286 unsigned long bdi_dirty
)
288 long numerator
, denominator
;
289 unsigned long dirty
= bdi_dirty
;
290 u64 inv
= dirty
/ TASK_LIMIT_FRACTION
;
292 task_dirties_fraction(tsk
, &numerator
, &denominator
);
294 do_div(inv
, denominator
);
298 return max(dirty
, bdi_dirty
/2);
301 /* Minimum limit for any task */
302 static unsigned long task_min_dirty_limit(unsigned long bdi_dirty
)
304 return bdi_dirty
- bdi_dirty
/ TASK_LIMIT_FRACTION
;
308 * bdi_min_ratio keeps the sum of the minimum dirty shares of all
309 * registered backing devices, which, for obvious reasons, can not
312 static unsigned int bdi_min_ratio
;
314 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
)
318 spin_lock_bh(&bdi_lock
);
319 if (min_ratio
> bdi
->max_ratio
) {
322 min_ratio
-= bdi
->min_ratio
;
323 if (bdi_min_ratio
+ min_ratio
< 100) {
324 bdi_min_ratio
+= min_ratio
;
325 bdi
->min_ratio
+= min_ratio
;
330 spin_unlock_bh(&bdi_lock
);
335 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned max_ratio
)
342 spin_lock_bh(&bdi_lock
);
343 if (bdi
->min_ratio
> max_ratio
) {
346 bdi
->max_ratio
= max_ratio
;
347 bdi
->max_prop_frac
= (PROP_FRAC_BASE
* max_ratio
) / 100;
349 spin_unlock_bh(&bdi_lock
);
353 EXPORT_SYMBOL(bdi_set_max_ratio
);
356 * Work out the current dirty-memory clamping and background writeout
359 * The main aim here is to lower them aggressively if there is a lot of mapped
360 * memory around. To avoid stressing page reclaim with lots of unreclaimable
361 * pages. It is better to clamp down on writers than to start swapping, and
362 * performing lots of scanning.
364 * We only allow 1/2 of the currently-unmapped memory to be dirtied.
366 * We don't permit the clamping level to fall below 5% - that is getting rather
369 * We make sure that the background writeout level is below the adjusted
373 static unsigned long highmem_dirtyable_memory(unsigned long total
)
375 #ifdef CONFIG_HIGHMEM
379 for_each_node_state(node
, N_HIGH_MEMORY
) {
381 &NODE_DATA(node
)->node_zones
[ZONE_HIGHMEM
];
383 x
+= zone_page_state(z
, NR_FREE_PAGES
) +
384 zone_reclaimable_pages(z
);
387 * Make sure that the number of highmem pages is never larger
388 * than the number of the total dirtyable memory. This can only
389 * occur in very strange VM situations but we want to make sure
390 * that this does not occur.
392 return min(x
, total
);
399 * determine_dirtyable_memory - amount of memory that may be used
401 * Returns the numebr of pages that can currently be freed and used
402 * by the kernel for direct mappings.
404 unsigned long determine_dirtyable_memory(void)
408 x
= global_page_state(NR_FREE_PAGES
) + global_reclaimable_pages();
410 if (!vm_highmem_is_dirtyable
)
411 x
-= highmem_dirtyable_memory(x
);
413 return x
+ 1; /* Ensure that we never return 0 */
416 static unsigned long hard_dirty_limit(unsigned long thresh
)
418 return max(thresh
, global_dirty_limit
);
422 * global_dirty_limits - background-writeback and dirty-throttling thresholds
424 * Calculate the dirty thresholds based on sysctl parameters
425 * - vm.dirty_background_ratio or vm.dirty_background_bytes
426 * - vm.dirty_ratio or vm.dirty_bytes
427 * The dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and
430 void global_dirty_limits(unsigned long *pbackground
, unsigned long *pdirty
)
432 unsigned long background
;
434 unsigned long uninitialized_var(available_memory
);
435 struct task_struct
*tsk
;
437 if (!vm_dirty_bytes
|| !dirty_background_bytes
)
438 available_memory
= determine_dirtyable_memory();
441 dirty
= DIV_ROUND_UP(vm_dirty_bytes
, PAGE_SIZE
);
443 dirty
= (vm_dirty_ratio
* available_memory
) / 100;
445 if (dirty_background_bytes
)
446 background
= DIV_ROUND_UP(dirty_background_bytes
, PAGE_SIZE
);
448 background
= (dirty_background_ratio
* available_memory
) / 100;
450 if (background
>= dirty
)
451 background
= dirty
/ 2;
453 if (tsk
->flags
& PF_LESS_THROTTLE
|| rt_task(tsk
)) {
454 background
+= background
/ 4;
457 *pbackground
= background
;
459 trace_global_dirty_state(background
, dirty
);
463 * bdi_dirty_limit - @bdi's share of dirty throttling threshold
464 * @bdi: the backing_dev_info to query
465 * @dirty: global dirty limit in pages
467 * Returns @bdi's dirty limit in pages. The term "dirty" in the context of
468 * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages.
469 * And the "limit" in the name is not seriously taken as hard limit in
470 * balance_dirty_pages().
472 * It allocates high/low dirty limits to fast/slow devices, in order to prevent
473 * - starving fast devices
474 * - piling up dirty pages (that will take long time to sync) on slow devices
476 * The bdi's share of dirty limit will be adapting to its throughput and
477 * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set.
479 unsigned long bdi_dirty_limit(struct backing_dev_info
*bdi
, unsigned long dirty
)
482 long numerator
, denominator
;
485 * Calculate this BDI's share of the dirty ratio.
487 bdi_writeout_fraction(bdi
, &numerator
, &denominator
);
489 bdi_dirty
= (dirty
* (100 - bdi_min_ratio
)) / 100;
490 bdi_dirty
*= numerator
;
491 do_div(bdi_dirty
, denominator
);
493 bdi_dirty
+= (dirty
* bdi
->min_ratio
) / 100;
494 if (bdi_dirty
> (dirty
* bdi
->max_ratio
) / 100)
495 bdi_dirty
= dirty
* bdi
->max_ratio
/ 100;
500 static void bdi_update_write_bandwidth(struct backing_dev_info
*bdi
,
501 unsigned long elapsed
,
502 unsigned long written
)
504 const unsigned long period
= roundup_pow_of_two(3 * HZ
);
505 unsigned long avg
= bdi
->avg_write_bandwidth
;
506 unsigned long old
= bdi
->write_bandwidth
;
510 * bw = written * HZ / elapsed
512 * bw * elapsed + write_bandwidth * (period - elapsed)
513 * write_bandwidth = ---------------------------------------------------
516 bw
= written
- bdi
->written_stamp
;
518 if (unlikely(elapsed
> period
)) {
523 bw
+= (u64
)bdi
->write_bandwidth
* (period
- elapsed
);
524 bw
>>= ilog2(period
);
527 * one more level of smoothing, for filtering out sudden spikes
529 if (avg
> old
&& old
>= (unsigned long)bw
)
530 avg
-= (avg
- old
) >> 3;
532 if (avg
< old
&& old
<= (unsigned long)bw
)
533 avg
+= (old
- avg
) >> 3;
536 bdi
->write_bandwidth
= bw
;
537 bdi
->avg_write_bandwidth
= avg
;
541 * The global dirtyable memory and dirty threshold could be suddenly knocked
542 * down by a large amount (eg. on the startup of KVM in a swapless system).
543 * This may throw the system into deep dirty exceeded state and throttle
544 * heavy/light dirtiers alike. To retain good responsiveness, maintain
545 * global_dirty_limit for tracking slowly down to the knocked down dirty
548 static void update_dirty_limit(unsigned long thresh
, unsigned long dirty
)
550 unsigned long limit
= global_dirty_limit
;
553 * Follow up in one step.
555 if (limit
< thresh
) {
561 * Follow down slowly. Use the higher one as the target, because thresh
562 * may drop below dirty. This is exactly the reason to introduce
563 * global_dirty_limit which is guaranteed to lie above the dirty pages.
565 thresh
= max(thresh
, dirty
);
566 if (limit
> thresh
) {
567 limit
-= (limit
- thresh
) >> 5;
572 global_dirty_limit
= limit
;
575 static void global_update_bandwidth(unsigned long thresh
,
579 static DEFINE_SPINLOCK(dirty_lock
);
580 static unsigned long update_time
;
583 * check locklessly first to optimize away locking for the most time
585 if (time_before(now
, update_time
+ BANDWIDTH_INTERVAL
))
588 spin_lock(&dirty_lock
);
589 if (time_after_eq(now
, update_time
+ BANDWIDTH_INTERVAL
)) {
590 update_dirty_limit(thresh
, dirty
);
593 spin_unlock(&dirty_lock
);
596 void __bdi_update_bandwidth(struct backing_dev_info
*bdi
,
597 unsigned long thresh
,
599 unsigned long bdi_thresh
,
600 unsigned long bdi_dirty
,
601 unsigned long start_time
)
603 unsigned long now
= jiffies
;
604 unsigned long elapsed
= now
- bdi
->bw_time_stamp
;
605 unsigned long written
;
608 * rate-limit, only update once every 200ms.
610 if (elapsed
< BANDWIDTH_INTERVAL
)
613 written
= percpu_counter_read(&bdi
->bdi_stat
[BDI_WRITTEN
]);
616 * Skip quiet periods when disk bandwidth is under-utilized.
617 * (at least 1s idle time between two flusher runs)
619 if (elapsed
> HZ
&& time_before(bdi
->bw_time_stamp
, start_time
))
623 global_update_bandwidth(thresh
, dirty
, now
);
625 bdi_update_write_bandwidth(bdi
, elapsed
, written
);
628 bdi
->written_stamp
= written
;
629 bdi
->bw_time_stamp
= now
;
632 static void bdi_update_bandwidth(struct backing_dev_info
*bdi
,
633 unsigned long thresh
,
635 unsigned long bdi_thresh
,
636 unsigned long bdi_dirty
,
637 unsigned long start_time
)
639 if (time_is_after_eq_jiffies(bdi
->bw_time_stamp
+ BANDWIDTH_INTERVAL
))
641 spin_lock(&bdi
->wb
.list_lock
);
642 __bdi_update_bandwidth(bdi
, thresh
, dirty
, bdi_thresh
, bdi_dirty
,
644 spin_unlock(&bdi
->wb
.list_lock
);
648 * balance_dirty_pages() must be called by processes which are generating dirty
649 * data. It looks at the number of dirty pages in the machine and will force
650 * the caller to perform writeback if the system is over `vm_dirty_ratio'.
651 * If we're over `background_thresh' then the writeback threads are woken to
652 * perform some writeout.
654 static void balance_dirty_pages(struct address_space
*mapping
,
655 unsigned long write_chunk
)
657 unsigned long nr_reclaimable
, bdi_nr_reclaimable
;
658 unsigned long nr_dirty
; /* = file_dirty + writeback + unstable_nfs */
659 unsigned long bdi_dirty
;
660 unsigned long background_thresh
;
661 unsigned long dirty_thresh
;
662 unsigned long bdi_thresh
;
663 unsigned long task_bdi_thresh
;
664 unsigned long min_task_bdi_thresh
;
665 unsigned long pages_written
= 0;
666 unsigned long pause
= 1;
667 bool dirty_exceeded
= false;
668 bool clear_dirty_exceeded
= true;
669 struct backing_dev_info
*bdi
= mapping
->backing_dev_info
;
670 unsigned long start_time
= jiffies
;
673 nr_reclaimable
= global_page_state(NR_FILE_DIRTY
) +
674 global_page_state(NR_UNSTABLE_NFS
);
675 nr_dirty
= nr_reclaimable
+ global_page_state(NR_WRITEBACK
);
677 global_dirty_limits(&background_thresh
, &dirty_thresh
);
680 * Throttle it only when the background writeback cannot
681 * catch-up. This avoids (excessively) small writeouts
682 * when the bdi limits are ramping up.
684 if (nr_dirty
<= (background_thresh
+ dirty_thresh
) / 2)
687 bdi_thresh
= bdi_dirty_limit(bdi
, dirty_thresh
);
688 min_task_bdi_thresh
= task_min_dirty_limit(bdi_thresh
);
689 task_bdi_thresh
= task_dirty_limit(current
, bdi_thresh
);
692 * In order to avoid the stacked BDI deadlock we need
693 * to ensure we accurately count the 'dirty' pages when
694 * the threshold is low.
696 * Otherwise it would be possible to get thresh+n pages
697 * reported dirty, even though there are thresh-m pages
698 * actually dirty; with m+n sitting in the percpu
701 if (task_bdi_thresh
< 2 * bdi_stat_error(bdi
)) {
702 bdi_nr_reclaimable
= bdi_stat_sum(bdi
, BDI_RECLAIMABLE
);
703 bdi_dirty
= bdi_nr_reclaimable
+
704 bdi_stat_sum(bdi
, BDI_WRITEBACK
);
706 bdi_nr_reclaimable
= bdi_stat(bdi
, BDI_RECLAIMABLE
);
707 bdi_dirty
= bdi_nr_reclaimable
+
708 bdi_stat(bdi
, BDI_WRITEBACK
);
712 * The bdi thresh is somehow "soft" limit derived from the
713 * global "hard" limit. The former helps to prevent heavy IO
714 * bdi or process from holding back light ones; The latter is
715 * the last resort safeguard.
717 dirty_exceeded
= (bdi_dirty
> task_bdi_thresh
) ||
718 (nr_dirty
> dirty_thresh
);
719 clear_dirty_exceeded
= (bdi_dirty
<= min_task_bdi_thresh
) &&
720 (nr_dirty
<= dirty_thresh
);
725 if (!bdi
->dirty_exceeded
)
726 bdi
->dirty_exceeded
= 1;
728 bdi_update_bandwidth(bdi
, dirty_thresh
, nr_dirty
,
729 bdi_thresh
, bdi_dirty
, start_time
);
731 /* Note: nr_reclaimable denotes nr_dirty + nr_unstable.
732 * Unstable writes are a feature of certain networked
733 * filesystems (i.e. NFS) in which data may have been
734 * written to the server's write cache, but has not yet
735 * been flushed to permanent storage.
736 * Only move pages to writeback if this bdi is over its
737 * threshold otherwise wait until the disk writes catch
740 trace_balance_dirty_start(bdi
);
741 if (bdi_nr_reclaimable
> task_bdi_thresh
) {
742 pages_written
+= writeback_inodes_wb(&bdi
->wb
,
744 trace_balance_dirty_written(bdi
, pages_written
);
745 if (pages_written
>= write_chunk
)
746 break; /* We've done our duty */
748 __set_current_state(TASK_UNINTERRUPTIBLE
);
749 io_schedule_timeout(pause
);
750 trace_balance_dirty_wait(bdi
);
752 dirty_thresh
= hard_dirty_limit(dirty_thresh
);
754 * max-pause area. If dirty exceeded but still within this
755 * area, no need to sleep for more than 200ms: (a) 8 pages per
756 * 200ms is typically more than enough to curb heavy dirtiers;
757 * (b) the pause time limit makes the dirtiers more responsive.
759 if (nr_dirty
< dirty_thresh
&&
760 bdi_dirty
< (task_bdi_thresh
+ bdi_thresh
) / 2 &&
761 time_after(jiffies
, start_time
+ MAX_PAUSE
))
765 * Increase the delay for each loop, up to our previous
766 * default of taking a 100ms nap.
773 /* Clear dirty_exceeded flag only when no task can exceed the limit */
774 if (clear_dirty_exceeded
&& bdi
->dirty_exceeded
)
775 bdi
->dirty_exceeded
= 0;
777 if (writeback_in_progress(bdi
))
781 * In laptop mode, we wait until hitting the higher threshold before
782 * starting background writeout, and then write out all the way down
783 * to the lower threshold. So slow writers cause minimal disk activity.
785 * In normal mode, we start background writeout at the lower
786 * background_thresh, to keep the amount of dirty memory low.
788 if ((laptop_mode
&& pages_written
) ||
789 (!laptop_mode
&& (nr_reclaimable
> background_thresh
)))
790 bdi_start_background_writeback(bdi
);
793 void set_page_dirty_balance(struct page
*page
, int page_mkwrite
)
795 if (set_page_dirty(page
) || page_mkwrite
) {
796 struct address_space
*mapping
= page_mapping(page
);
799 balance_dirty_pages_ratelimited(mapping
);
803 static DEFINE_PER_CPU(unsigned long, bdp_ratelimits
) = 0;
806 * balance_dirty_pages_ratelimited_nr - balance dirty memory state
807 * @mapping: address_space which was dirtied
808 * @nr_pages_dirtied: number of pages which the caller has just dirtied
810 * Processes which are dirtying memory should call in here once for each page
811 * which was newly dirtied. The function will periodically check the system's
812 * dirty state and will initiate writeback if needed.
814 * On really big machines, get_writeback_state is expensive, so try to avoid
815 * calling it too often (ratelimiting). But once we're over the dirty memory
816 * limit we decrease the ratelimiting by a lot, to prevent individual processes
817 * from overshooting the limit by (ratelimit_pages) each.
819 void balance_dirty_pages_ratelimited_nr(struct address_space
*mapping
,
820 unsigned long nr_pages_dirtied
)
822 struct backing_dev_info
*bdi
= mapping
->backing_dev_info
;
823 unsigned long ratelimit
;
826 if (!bdi_cap_account_dirty(bdi
))
829 ratelimit
= ratelimit_pages
;
830 if (mapping
->backing_dev_info
->dirty_exceeded
)
834 * Check the rate limiting. Also, we do not want to throttle real-time
835 * tasks in balance_dirty_pages(). Period.
838 p
= &__get_cpu_var(bdp_ratelimits
);
839 *p
+= nr_pages_dirtied
;
840 if (unlikely(*p
>= ratelimit
)) {
841 ratelimit
= sync_writeback_pages(*p
);
844 balance_dirty_pages(mapping
, ratelimit
);
849 EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr
);
851 void throttle_vm_writeout(gfp_t gfp_mask
)
853 unsigned long background_thresh
;
854 unsigned long dirty_thresh
;
857 global_dirty_limits(&background_thresh
, &dirty_thresh
);
860 * Boost the allowable dirty threshold a bit for page
861 * allocators so they don't get DoS'ed by heavy writers
863 dirty_thresh
+= dirty_thresh
/ 10; /* wheeee... */
865 if (global_page_state(NR_UNSTABLE_NFS
) +
866 global_page_state(NR_WRITEBACK
) <= dirty_thresh
)
868 congestion_wait(BLK_RW_ASYNC
, HZ
/10);
871 * The caller might hold locks which can prevent IO completion
872 * or progress in the filesystem. So we cannot just sit here
873 * waiting for IO to complete.
875 if ((gfp_mask
& (__GFP_FS
|__GFP_IO
)) != (__GFP_FS
|__GFP_IO
))
881 * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs
883 int dirty_writeback_centisecs_handler(ctl_table
*table
, int write
,
884 void __user
*buffer
, size_t *length
, loff_t
*ppos
)
886 proc_dointvec(table
, write
, buffer
, length
, ppos
);
887 bdi_arm_supers_timer();
892 void laptop_mode_timer_fn(unsigned long data
)
894 struct request_queue
*q
= (struct request_queue
*)data
;
895 int nr_pages
= global_page_state(NR_FILE_DIRTY
) +
896 global_page_state(NR_UNSTABLE_NFS
);
899 * We want to write everything out, not just down to the dirty
902 if (bdi_has_dirty_io(&q
->backing_dev_info
))
903 bdi_start_writeback(&q
->backing_dev_info
, nr_pages
);
907 * We've spun up the disk and we're in laptop mode: schedule writeback
908 * of all dirty data a few seconds from now. If the flush is already scheduled
909 * then push it back - the user is still using the disk.
911 void laptop_io_completion(struct backing_dev_info
*info
)
913 mod_timer(&info
->laptop_mode_wb_timer
, jiffies
+ laptop_mode
);
917 * We're in laptop mode and we've just synced. The sync's writes will have
918 * caused another writeback to be scheduled by laptop_io_completion.
919 * Nothing needs to be written back anymore, so we unschedule the writeback.
921 void laptop_sync_completion(void)
923 struct backing_dev_info
*bdi
;
927 list_for_each_entry_rcu(bdi
, &bdi_list
, bdi_list
)
928 del_timer(&bdi
->laptop_mode_wb_timer
);
935 * If ratelimit_pages is too high then we can get into dirty-data overload
936 * if a large number of processes all perform writes at the same time.
937 * If it is too low then SMP machines will call the (expensive)
938 * get_writeback_state too often.
940 * Here we set ratelimit_pages to a level which ensures that when all CPUs are
941 * dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory
942 * thresholds before writeback cuts in.
944 * But the limit should not be set too high. Because it also controls the
945 * amount of memory which the balance_dirty_pages() caller has to write back.
946 * If this is too large then the caller will block on the IO queue all the
947 * time. So limit it to four megabytes - the balance_dirty_pages() caller
948 * will write six megabyte chunks, max.
951 void writeback_set_ratelimit(void)
953 ratelimit_pages
= vm_total_pages
/ (num_online_cpus() * 32);
954 if (ratelimit_pages
< 16)
955 ratelimit_pages
= 16;
956 if (ratelimit_pages
* PAGE_CACHE_SIZE
> 4096 * 1024)
957 ratelimit_pages
= (4096 * 1024) / PAGE_CACHE_SIZE
;
961 ratelimit_handler(struct notifier_block
*self
, unsigned long u
, void *v
)
963 writeback_set_ratelimit();
967 static struct notifier_block __cpuinitdata ratelimit_nb
= {
968 .notifier_call
= ratelimit_handler
,
973 * Called early on to tune the page writeback dirty limits.
975 * We used to scale dirty pages according to how total memory
976 * related to pages that could be allocated for buffers (by
977 * comparing nr_free_buffer_pages() to vm_total_pages.
979 * However, that was when we used "dirty_ratio" to scale with
980 * all memory, and we don't do that any more. "dirty_ratio"
981 * is now applied to total non-HIGHPAGE memory (by subtracting
982 * totalhigh_pages from vm_total_pages), and as such we can't
983 * get into the old insane situation any more where we had
984 * large amounts of dirty pages compared to a small amount of
985 * non-HIGHMEM memory.
987 * But we might still want to scale the dirty_ratio by how
988 * much memory the box has..
990 void __init
page_writeback_init(void)
994 writeback_set_ratelimit();
995 register_cpu_notifier(&ratelimit_nb
);
997 shift
= calc_period_shift();
998 prop_descriptor_init(&vm_completions
, shift
);
999 prop_descriptor_init(&vm_dirties
, shift
);
1003 * tag_pages_for_writeback - tag pages to be written by write_cache_pages
1004 * @mapping: address space structure to write
1005 * @start: starting page index
1006 * @end: ending page index (inclusive)
1008 * This function scans the page range from @start to @end (inclusive) and tags
1009 * all pages that have DIRTY tag set with a special TOWRITE tag. The idea is
1010 * that write_cache_pages (or whoever calls this function) will then use
1011 * TOWRITE tag to identify pages eligible for writeback. This mechanism is
1012 * used to avoid livelocking of writeback by a process steadily creating new
1013 * dirty pages in the file (thus it is important for this function to be quick
1014 * so that it can tag pages faster than a dirtying process can create them).
1017 * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce tree_lock latency.
1019 void tag_pages_for_writeback(struct address_space
*mapping
,
1020 pgoff_t start
, pgoff_t end
)
1022 #define WRITEBACK_TAG_BATCH 4096
1023 unsigned long tagged
;
1026 spin_lock_irq(&mapping
->tree_lock
);
1027 tagged
= radix_tree_range_tag_if_tagged(&mapping
->page_tree
,
1028 &start
, end
, WRITEBACK_TAG_BATCH
,
1029 PAGECACHE_TAG_DIRTY
, PAGECACHE_TAG_TOWRITE
);
1030 spin_unlock_irq(&mapping
->tree_lock
);
1031 WARN_ON_ONCE(tagged
> WRITEBACK_TAG_BATCH
);
1033 /* We check 'start' to handle wrapping when end == ~0UL */
1034 } while (tagged
>= WRITEBACK_TAG_BATCH
&& start
);
1036 EXPORT_SYMBOL(tag_pages_for_writeback
);
1039 * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
1040 * @mapping: address space structure to write
1041 * @wbc: subtract the number of written pages from *@wbc->nr_to_write
1042 * @writepage: function called for each page
1043 * @data: data passed to writepage function
1045 * If a page is already under I/O, write_cache_pages() skips it, even
1046 * if it's dirty. This is desirable behaviour for memory-cleaning writeback,
1047 * but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
1048 * and msync() need to guarantee that all the data which was dirty at the time
1049 * the call was made get new I/O started against them. If wbc->sync_mode is
1050 * WB_SYNC_ALL then we were called for data integrity and we must wait for
1051 * existing IO to complete.
1053 * To avoid livelocks (when other process dirties new pages), we first tag
1054 * pages which should be written back with TOWRITE tag and only then start
1055 * writing them. For data-integrity sync we have to be careful so that we do
1056 * not miss some pages (e.g., because some other process has cleared TOWRITE
1057 * tag we set). The rule we follow is that TOWRITE tag can be cleared only
1058 * by the process clearing the DIRTY tag (and submitting the page for IO).
1060 int write_cache_pages(struct address_space
*mapping
,
1061 struct writeback_control
*wbc
, writepage_t writepage
,
1066 struct pagevec pvec
;
1068 pgoff_t
uninitialized_var(writeback_index
);
1070 pgoff_t end
; /* Inclusive */
1073 int range_whole
= 0;
1076 pagevec_init(&pvec
, 0);
1077 if (wbc
->range_cyclic
) {
1078 writeback_index
= mapping
->writeback_index
; /* prev offset */
1079 index
= writeback_index
;
1086 index
= wbc
->range_start
>> PAGE_CACHE_SHIFT
;
1087 end
= wbc
->range_end
>> PAGE_CACHE_SHIFT
;
1088 if (wbc
->range_start
== 0 && wbc
->range_end
== LLONG_MAX
)
1090 cycled
= 1; /* ignore range_cyclic tests */
1092 if (wbc
->sync_mode
== WB_SYNC_ALL
|| wbc
->tagged_writepages
)
1093 tag
= PAGECACHE_TAG_TOWRITE
;
1095 tag
= PAGECACHE_TAG_DIRTY
;
1097 if (wbc
->sync_mode
== WB_SYNC_ALL
|| wbc
->tagged_writepages
)
1098 tag_pages_for_writeback(mapping
, index
, end
);
1100 while (!done
&& (index
<= end
)) {
1103 nr_pages
= pagevec_lookup_tag(&pvec
, mapping
, &index
, tag
,
1104 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
-1) + 1);
1108 for (i
= 0; i
< nr_pages
; i
++) {
1109 struct page
*page
= pvec
.pages
[i
];
1112 * At this point, the page may be truncated or
1113 * invalidated (changing page->mapping to NULL), or
1114 * even swizzled back from swapper_space to tmpfs file
1115 * mapping. However, page->index will not change
1116 * because we have a reference on the page.
1118 if (page
->index
> end
) {
1120 * can't be range_cyclic (1st pass) because
1121 * end == -1 in that case.
1127 done_index
= page
->index
;
1132 * Page truncated or invalidated. We can freely skip it
1133 * then, even for data integrity operations: the page
1134 * has disappeared concurrently, so there could be no
1135 * real expectation of this data interity operation
1136 * even if there is now a new, dirty page at the same
1137 * pagecache address.
1139 if (unlikely(page
->mapping
!= mapping
)) {
1145 if (!PageDirty(page
)) {
1146 /* someone wrote it for us */
1147 goto continue_unlock
;
1150 if (PageWriteback(page
)) {
1151 if (wbc
->sync_mode
!= WB_SYNC_NONE
)
1152 wait_on_page_writeback(page
);
1154 goto continue_unlock
;
1157 BUG_ON(PageWriteback(page
));
1158 if (!clear_page_dirty_for_io(page
))
1159 goto continue_unlock
;
1161 trace_wbc_writepage(wbc
, mapping
->backing_dev_info
);
1162 ret
= (*writepage
)(page
, wbc
, data
);
1163 if (unlikely(ret
)) {
1164 if (ret
== AOP_WRITEPAGE_ACTIVATE
) {
1169 * done_index is set past this page,
1170 * so media errors will not choke
1171 * background writeout for the entire
1172 * file. This has consequences for
1173 * range_cyclic semantics (ie. it may
1174 * not be suitable for data integrity
1177 done_index
= page
->index
+ 1;
1184 * We stop writing back only if we are not doing
1185 * integrity sync. In case of integrity sync we have to
1186 * keep going until we have written all the pages
1187 * we tagged for writeback prior to entering this loop.
1189 if (--wbc
->nr_to_write
<= 0 &&
1190 wbc
->sync_mode
== WB_SYNC_NONE
) {
1195 pagevec_release(&pvec
);
1198 if (!cycled
&& !done
) {
1201 * We hit the last page and there is more work to be done: wrap
1202 * back to the start of the file
1206 end
= writeback_index
- 1;
1209 if (wbc
->range_cyclic
|| (range_whole
&& wbc
->nr_to_write
> 0))
1210 mapping
->writeback_index
= done_index
;
1214 EXPORT_SYMBOL(write_cache_pages
);
1217 * Function used by generic_writepages to call the real writepage
1218 * function and set the mapping flags on error
1220 static int __writepage(struct page
*page
, struct writeback_control
*wbc
,
1223 struct address_space
*mapping
= data
;
1224 int ret
= mapping
->a_ops
->writepage(page
, wbc
);
1225 mapping_set_error(mapping
, ret
);
1230 * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
1231 * @mapping: address space structure to write
1232 * @wbc: subtract the number of written pages from *@wbc->nr_to_write
1234 * This is a library function, which implements the writepages()
1235 * address_space_operation.
1237 int generic_writepages(struct address_space
*mapping
,
1238 struct writeback_control
*wbc
)
1240 struct blk_plug plug
;
1243 /* deal with chardevs and other special file */
1244 if (!mapping
->a_ops
->writepage
)
1247 blk_start_plug(&plug
);
1248 ret
= write_cache_pages(mapping
, wbc
, __writepage
, mapping
);
1249 blk_finish_plug(&plug
);
1253 EXPORT_SYMBOL(generic_writepages
);
1255 int do_writepages(struct address_space
*mapping
, struct writeback_control
*wbc
)
1259 if (wbc
->nr_to_write
<= 0)
1261 if (mapping
->a_ops
->writepages
)
1262 ret
= mapping
->a_ops
->writepages(mapping
, wbc
);
1264 ret
= generic_writepages(mapping
, wbc
);
1269 * write_one_page - write out a single page and optionally wait on I/O
1270 * @page: the page to write
1271 * @wait: if true, wait on writeout
1273 * The page must be locked by the caller and will be unlocked upon return.
1275 * write_one_page() returns a negative error code if I/O failed.
1277 int write_one_page(struct page
*page
, int wait
)
1279 struct address_space
*mapping
= page
->mapping
;
1281 struct writeback_control wbc
= {
1282 .sync_mode
= WB_SYNC_ALL
,
1286 BUG_ON(!PageLocked(page
));
1289 wait_on_page_writeback(page
);
1291 if (clear_page_dirty_for_io(page
)) {
1292 page_cache_get(page
);
1293 ret
= mapping
->a_ops
->writepage(page
, &wbc
);
1294 if (ret
== 0 && wait
) {
1295 wait_on_page_writeback(page
);
1296 if (PageError(page
))
1299 page_cache_release(page
);
1305 EXPORT_SYMBOL(write_one_page
);
1308 * For address_spaces which do not use buffers nor write back.
1310 int __set_page_dirty_no_writeback(struct page
*page
)
1312 if (!PageDirty(page
))
1313 return !TestSetPageDirty(page
);
1318 * Helper function for set_page_dirty family.
1319 * NOTE: This relies on being atomic wrt interrupts.
1321 void account_page_dirtied(struct page
*page
, struct address_space
*mapping
)
1323 if (mapping_cap_account_dirty(mapping
)) {
1324 __inc_zone_page_state(page
, NR_FILE_DIRTY
);
1325 __inc_zone_page_state(page
, NR_DIRTIED
);
1326 __inc_bdi_stat(mapping
->backing_dev_info
, BDI_RECLAIMABLE
);
1327 task_dirty_inc(current
);
1328 task_io_account_write(PAGE_CACHE_SIZE
);
1331 EXPORT_SYMBOL(account_page_dirtied
);
1334 * Helper function for set_page_writeback family.
1335 * NOTE: Unlike account_page_dirtied this does not rely on being atomic
1338 void account_page_writeback(struct page
*page
)
1340 inc_zone_page_state(page
, NR_WRITEBACK
);
1342 EXPORT_SYMBOL(account_page_writeback
);
1345 * For address_spaces which do not use buffers. Just tag the page as dirty in
1348 * This is also used when a single buffer is being dirtied: we want to set the
1349 * page dirty in that case, but not all the buffers. This is a "bottom-up"
1350 * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying.
1352 * Most callers have locked the page, which pins the address_space in memory.
1353 * But zap_pte_range() does not lock the page, however in that case the
1354 * mapping is pinned by the vma's ->vm_file reference.
1356 * We take care to handle the case where the page was truncated from the
1357 * mapping by re-checking page_mapping() inside tree_lock.
1359 int __set_page_dirty_nobuffers(struct page
*page
)
1361 if (!TestSetPageDirty(page
)) {
1362 struct address_space
*mapping
= page_mapping(page
);
1363 struct address_space
*mapping2
;
1368 spin_lock_irq(&mapping
->tree_lock
);
1369 mapping2
= page_mapping(page
);
1370 if (mapping2
) { /* Race with truncate? */
1371 BUG_ON(mapping2
!= mapping
);
1372 WARN_ON_ONCE(!PagePrivate(page
) && !PageUptodate(page
));
1373 account_page_dirtied(page
, mapping
);
1374 radix_tree_tag_set(&mapping
->page_tree
,
1375 page_index(page
), PAGECACHE_TAG_DIRTY
);
1377 spin_unlock_irq(&mapping
->tree_lock
);
1378 if (mapping
->host
) {
1379 /* !PageAnon && !swapper_space */
1380 __mark_inode_dirty(mapping
->host
, I_DIRTY_PAGES
);
1386 EXPORT_SYMBOL(__set_page_dirty_nobuffers
);
1389 * When a writepage implementation decides that it doesn't want to write this
1390 * page for some reason, it should redirty the locked page via
1391 * redirty_page_for_writepage() and it should then unlock the page and return 0
1393 int redirty_page_for_writepage(struct writeback_control
*wbc
, struct page
*page
)
1395 wbc
->pages_skipped
++;
1396 return __set_page_dirty_nobuffers(page
);
1398 EXPORT_SYMBOL(redirty_page_for_writepage
);
1403 * For pages with a mapping this should be done under the page lock
1404 * for the benefit of asynchronous memory errors who prefer a consistent
1405 * dirty state. This rule can be broken in some special cases,
1406 * but should be better not to.
1408 * If the mapping doesn't provide a set_page_dirty a_op, then
1409 * just fall through and assume that it wants buffer_heads.
1411 int set_page_dirty(struct page
*page
)
1413 struct address_space
*mapping
= page_mapping(page
);
1415 if (likely(mapping
)) {
1416 int (*spd
)(struct page
*) = mapping
->a_ops
->set_page_dirty
;
1418 * readahead/lru_deactivate_page could remain
1419 * PG_readahead/PG_reclaim due to race with end_page_writeback
1420 * About readahead, if the page is written, the flags would be
1421 * reset. So no problem.
1422 * About lru_deactivate_page, if the page is redirty, the flag
1423 * will be reset. So no problem. but if the page is used by readahead
1424 * it will confuse readahead and make it restart the size rampup
1425 * process. But it's a trivial problem.
1427 ClearPageReclaim(page
);
1430 spd
= __set_page_dirty_buffers
;
1432 return (*spd
)(page
);
1434 if (!PageDirty(page
)) {
1435 if (!TestSetPageDirty(page
))
1440 EXPORT_SYMBOL(set_page_dirty
);
1443 * set_page_dirty() is racy if the caller has no reference against
1444 * page->mapping->host, and if the page is unlocked. This is because another
1445 * CPU could truncate the page off the mapping and then free the mapping.
1447 * Usually, the page _is_ locked, or the caller is a user-space process which
1448 * holds a reference on the inode by having an open file.
1450 * In other cases, the page should be locked before running set_page_dirty().
1452 int set_page_dirty_lock(struct page
*page
)
1457 ret
= set_page_dirty(page
);
1461 EXPORT_SYMBOL(set_page_dirty_lock
);
1464 * Clear a page's dirty flag, while caring for dirty memory accounting.
1465 * Returns true if the page was previously dirty.
1467 * This is for preparing to put the page under writeout. We leave the page
1468 * tagged as dirty in the radix tree so that a concurrent write-for-sync
1469 * can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage
1470 * implementation will run either set_page_writeback() or set_page_dirty(),
1471 * at which stage we bring the page's dirty flag and radix-tree dirty tag
1474 * This incoherency between the page's dirty flag and radix-tree tag is
1475 * unfortunate, but it only exists while the page is locked.
1477 int clear_page_dirty_for_io(struct page
*page
)
1479 struct address_space
*mapping
= page_mapping(page
);
1481 BUG_ON(!PageLocked(page
));
1483 if (mapping
&& mapping_cap_account_dirty(mapping
)) {
1485 * Yes, Virginia, this is indeed insane.
1487 * We use this sequence to make sure that
1488 * (a) we account for dirty stats properly
1489 * (b) we tell the low-level filesystem to
1490 * mark the whole page dirty if it was
1491 * dirty in a pagetable. Only to then
1492 * (c) clean the page again and return 1 to
1493 * cause the writeback.
1495 * This way we avoid all nasty races with the
1496 * dirty bit in multiple places and clearing
1497 * them concurrently from different threads.
1499 * Note! Normally the "set_page_dirty(page)"
1500 * has no effect on the actual dirty bit - since
1501 * that will already usually be set. But we
1502 * need the side effects, and it can help us
1505 * We basically use the page "master dirty bit"
1506 * as a serialization point for all the different
1507 * threads doing their things.
1509 if (page_mkclean(page
))
1510 set_page_dirty(page
);
1512 * We carefully synchronise fault handlers against
1513 * installing a dirty pte and marking the page dirty
1514 * at this point. We do this by having them hold the
1515 * page lock at some point after installing their
1516 * pte, but before marking the page dirty.
1517 * Pages are always locked coming in here, so we get
1518 * the desired exclusion. See mm/memory.c:do_wp_page()
1519 * for more comments.
1521 if (TestClearPageDirty(page
)) {
1522 dec_zone_page_state(page
, NR_FILE_DIRTY
);
1523 dec_bdi_stat(mapping
->backing_dev_info
,
1529 return TestClearPageDirty(page
);
1531 EXPORT_SYMBOL(clear_page_dirty_for_io
);
1533 int test_clear_page_writeback(struct page
*page
)
1535 struct address_space
*mapping
= page_mapping(page
);
1539 struct backing_dev_info
*bdi
= mapping
->backing_dev_info
;
1540 unsigned long flags
;
1542 spin_lock_irqsave(&mapping
->tree_lock
, flags
);
1543 ret
= TestClearPageWriteback(page
);
1545 radix_tree_tag_clear(&mapping
->page_tree
,
1547 PAGECACHE_TAG_WRITEBACK
);
1548 if (bdi_cap_account_writeback(bdi
)) {
1549 __dec_bdi_stat(bdi
, BDI_WRITEBACK
);
1550 __bdi_writeout_inc(bdi
);
1553 spin_unlock_irqrestore(&mapping
->tree_lock
, flags
);
1555 ret
= TestClearPageWriteback(page
);
1558 dec_zone_page_state(page
, NR_WRITEBACK
);
1559 inc_zone_page_state(page
, NR_WRITTEN
);
1564 int test_set_page_writeback(struct page
*page
)
1566 struct address_space
*mapping
= page_mapping(page
);
1570 struct backing_dev_info
*bdi
= mapping
->backing_dev_info
;
1571 unsigned long flags
;
1573 spin_lock_irqsave(&mapping
->tree_lock
, flags
);
1574 ret
= TestSetPageWriteback(page
);
1576 radix_tree_tag_set(&mapping
->page_tree
,
1578 PAGECACHE_TAG_WRITEBACK
);
1579 if (bdi_cap_account_writeback(bdi
))
1580 __inc_bdi_stat(bdi
, BDI_WRITEBACK
);
1582 if (!PageDirty(page
))
1583 radix_tree_tag_clear(&mapping
->page_tree
,
1585 PAGECACHE_TAG_DIRTY
);
1586 radix_tree_tag_clear(&mapping
->page_tree
,
1588 PAGECACHE_TAG_TOWRITE
);
1589 spin_unlock_irqrestore(&mapping
->tree_lock
, flags
);
1591 ret
= TestSetPageWriteback(page
);
1594 account_page_writeback(page
);
1598 EXPORT_SYMBOL(test_set_page_writeback
);
1601 * Return true if any of the pages in the mapping are marked with the
1604 int mapping_tagged(struct address_space
*mapping
, int tag
)
1606 return radix_tree_tagged(&mapping
->page_tree
, tag
);
1608 EXPORT_SYMBOL(mapping_tagged
);