/*
|
/*
|
* mm/page-writeback.c
|
* mm/page-writeback.c
|
*
|
*
|
* Copyright (C) 2002, Linus Torvalds.
|
* Copyright (C) 2002, Linus Torvalds.
|
* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
|
* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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*
|
*
|
* Contains functions related to writing back dirty pages at the
|
* Contains functions related to writing back dirty pages at the
|
* address_space level.
|
* address_space level.
|
*
|
*
|
* 10Apr2002 akpm@zip.com.au
|
* 10Apr2002 akpm@zip.com.au
|
* Initial version
|
* Initial version
|
*/
|
*/
|
|
|
#include <linux/kernel.h>
|
#include <linux/kernel.h>
|
#include <linux/module.h>
|
#include <linux/module.h>
|
#include <linux/spinlock.h>
|
#include <linux/spinlock.h>
|
#include <linux/fs.h>
|
#include <linux/fs.h>
|
#include <linux/mm.h>
|
#include <linux/mm.h>
|
#include <linux/swap.h>
|
#include <linux/swap.h>
|
#include <linux/slab.h>
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#include <linux/slab.h>
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#include <linux/pagemap.h>
|
#include <linux/pagemap.h>
|
#include <linux/writeback.h>
|
#include <linux/writeback.h>
|
#include <linux/init.h>
|
#include <linux/init.h>
|
#include <linux/backing-dev.h>
|
#include <linux/backing-dev.h>
|
#include <linux/task_io_accounting_ops.h>
|
#include <linux/task_io_accounting_ops.h>
|
#include <linux/blkdev.h>
|
#include <linux/blkdev.h>
|
#include <linux/mpage.h>
|
#include <linux/mpage.h>
|
#include <linux/rmap.h>
|
#include <linux/rmap.h>
|
#include <linux/percpu.h>
|
#include <linux/percpu.h>
|
#include <linux/notifier.h>
|
#include <linux/notifier.h>
|
#include <linux/smp.h>
|
#include <linux/smp.h>
|
#include <linux/sysctl.h>
|
#include <linux/sysctl.h>
|
#include <linux/cpu.h>
|
#include <linux/cpu.h>
|
#include <linux/syscalls.h>
|
#include <linux/syscalls.h>
|
#include <linux/buffer_head.h>
|
#include <linux/buffer_head.h>
|
#include <linux/pagevec.h>
|
#include <linux/pagevec.h>
|
|
|
/*
|
/*
|
* The maximum number of pages to writeout in a single bdflush/kupdate
|
* The maximum number of pages to writeout in a single bdflush/kupdate
|
* operation. We do this so we don't hold I_SYNC against an inode for
|
* operation. We do this so we don't hold I_SYNC against an inode for
|
* enormous amounts of time, which would block a userspace task which has
|
* enormous amounts of time, which would block a userspace task which has
|
* been forced to throttle against that inode. Also, the code reevaluates
|
* been forced to throttle against that inode. Also, the code reevaluates
|
* the dirty each time it has written this many pages.
|
* the dirty each time it has written this many pages.
|
*/
|
*/
|
#define MAX_WRITEBACK_PAGES 1024
|
#define MAX_WRITEBACK_PAGES 1024
|
|
|
/*
|
/*
|
* After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited
|
* After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited
|
* will look to see if it needs to force writeback or throttling.
|
* will look to see if it needs to force writeback or throttling.
|
*/
|
*/
|
static long ratelimit_pages = 32;
|
static long ratelimit_pages = 32;
|
|
|
/*
|
/*
|
* When balance_dirty_pages decides that the caller needs to perform some
|
* When balance_dirty_pages decides that the caller needs to perform some
|
* non-background writeback, this is how many pages it will attempt to write.
|
* non-background writeback, this is how many pages it will attempt to write.
|
* It should be somewhat larger than RATELIMIT_PAGES to ensure that reasonably
|
* It should be somewhat larger than RATELIMIT_PAGES to ensure that reasonably
|
* large amounts of I/O are submitted.
|
* large amounts of I/O are submitted.
|
*/
|
*/
|
static inline long sync_writeback_pages(void)
|
static inline long sync_writeback_pages(void)
|
{
|
{
|
return ratelimit_pages + ratelimit_pages / 2;
|
return ratelimit_pages + ratelimit_pages / 2;
|
}
|
}
|
|
|
/* The following parameters are exported via /proc/sys/vm */
|
/* The following parameters are exported via /proc/sys/vm */
|
|
|
/*
|
/*
|
* Start background writeback (via pdflush) at this percentage
|
* Start background writeback (via pdflush) at this percentage
|
*/
|
*/
|
int dirty_background_ratio = 5;
|
int dirty_background_ratio = 5;
|
|
|
/*
|
/*
|
* The generator of dirty data starts writeback at this percentage
|
* The generator of dirty data starts writeback at this percentage
|
*/
|
*/
|
int vm_dirty_ratio = 10;
|
int vm_dirty_ratio = 10;
|
|
|
/*
|
/*
|
* The interval between `kupdate'-style writebacks, in jiffies
|
* The interval between `kupdate'-style writebacks, in jiffies
|
*/
|
*/
|
int dirty_writeback_interval = 5 * HZ;
|
int dirty_writeback_interval = 5 * HZ;
|
|
|
/*
|
/*
|
* The longest number of jiffies for which data is allowed to remain dirty
|
* The longest number of jiffies for which data is allowed to remain dirty
|
*/
|
*/
|
int dirty_expire_interval = 30 * HZ;
|
int dirty_expire_interval = 30 * HZ;
|
|
|
/*
|
/*
|
* Flag that makes the machine dump writes/reads and block dirtyings.
|
* Flag that makes the machine dump writes/reads and block dirtyings.
|
*/
|
*/
|
int block_dump;
|
int block_dump;
|
|
|
/*
|
/*
|
* Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies:
|
* Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies:
|
* a full sync is triggered after this time elapses without any disk activity.
|
* a full sync is triggered after this time elapses without any disk activity.
|
*/
|
*/
|
int laptop_mode;
|
int laptop_mode;
|
|
|
EXPORT_SYMBOL(laptop_mode);
|
EXPORT_SYMBOL(laptop_mode);
|
|
|
/* End of sysctl-exported parameters */
|
/* End of sysctl-exported parameters */
|
|
|
|
|
static void background_writeout(unsigned long _min_pages);
|
static void background_writeout(unsigned long _min_pages);
|
|
|
/*
|
/*
|
* Scale the writeback cache size proportional to the relative writeout speeds.
|
* Scale the writeback cache size proportional to the relative writeout speeds.
|
*
|
*
|
* We do this by keeping a floating proportion between BDIs, based on page
|
* We do this by keeping a floating proportion between BDIs, based on page
|
* writeback completions [end_page_writeback()]. Those devices that write out
|
* writeback completions [end_page_writeback()]. Those devices that write out
|
* pages fastest will get the larger share, while the slower will get a smaller
|
* pages fastest will get the larger share, while the slower will get a smaller
|
* share.
|
* share.
|
*
|
*
|
* We use page writeout completions because we are interested in getting rid of
|
* We use page writeout completions because we are interested in getting rid of
|
* dirty pages. Having them written out is the primary goal.
|
* dirty pages. Having them written out is the primary goal.
|
*
|
*
|
* We introduce a concept of time, a period over which we measure these events,
|
* We introduce a concept of time, a period over which we measure these events,
|
* because demand can/will vary over time. The length of this period itself is
|
* because demand can/will vary over time. The length of this period itself is
|
* measured in page writeback completions.
|
* measured in page writeback completions.
|
*
|
*
|
*/
|
*/
|
static struct prop_descriptor vm_completions;
|
static struct prop_descriptor vm_completions;
|
static struct prop_descriptor vm_dirties;
|
static struct prop_descriptor vm_dirties;
|
|
|
static unsigned long determine_dirtyable_memory(void);
|
static unsigned long determine_dirtyable_memory(void);
|
|
|
/*
|
/*
|
* couple the period to the dirty_ratio:
|
* couple the period to the dirty_ratio:
|
*
|
*
|
* period/2 ~ roundup_pow_of_two(dirty limit)
|
* period/2 ~ roundup_pow_of_two(dirty limit)
|
*/
|
*/
|
static int calc_period_shift(void)
|
static int calc_period_shift(void)
|
{
|
{
|
unsigned long dirty_total;
|
unsigned long dirty_total;
|
|
|
dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) / 100;
|
dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) / 100;
|
return 2 + ilog2(dirty_total - 1);
|
return 2 + ilog2(dirty_total - 1);
|
}
|
}
|
|
|
/*
|
/*
|
* update the period when the dirty ratio changes.
|
* update the period when the dirty ratio changes.
|
*/
|
*/
|
int dirty_ratio_handler(struct ctl_table *table, int write,
|
int dirty_ratio_handler(struct ctl_table *table, int write,
|
struct file *filp, void __user *buffer, size_t *lenp,
|
struct file *filp, void __user *buffer, size_t *lenp,
|
loff_t *ppos)
|
loff_t *ppos)
|
{
|
{
|
int old_ratio = vm_dirty_ratio;
|
int old_ratio = vm_dirty_ratio;
|
int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
|
int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
|
if (ret == 0 && write && vm_dirty_ratio != old_ratio) {
|
if (ret == 0 && write && vm_dirty_ratio != old_ratio) {
|
int shift = calc_period_shift();
|
int shift = calc_period_shift();
|
prop_change_shift(&vm_completions, shift);
|
prop_change_shift(&vm_completions, shift);
|
prop_change_shift(&vm_dirties, shift);
|
prop_change_shift(&vm_dirties, shift);
|
}
|
}
|
return ret;
|
return ret;
|
}
|
}
|
|
|
/*
|
/*
|
* Increment the BDI's writeout completion count and the global writeout
|
* Increment the BDI's writeout completion count and the global writeout
|
* completion count. Called from test_clear_page_writeback().
|
* completion count. Called from test_clear_page_writeback().
|
*/
|
*/
|
static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
|
static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
|
{
|
{
|
__prop_inc_percpu(&vm_completions, &bdi->completions);
|
__prop_inc_percpu(&vm_completions, &bdi->completions);
|
}
|
}
|
|
|
static inline void task_dirty_inc(struct task_struct *tsk)
|
static inline void task_dirty_inc(struct task_struct *tsk)
|
{
|
{
|
prop_inc_single(&vm_dirties, &tsk->dirties);
|
prop_inc_single(&vm_dirties, &tsk->dirties);
|
}
|
}
|
|
|
/*
|
/*
|
* Obtain an accurate fraction of the BDI's portion.
|
* Obtain an accurate fraction of the BDI's portion.
|
*/
|
*/
|
static void bdi_writeout_fraction(struct backing_dev_info *bdi,
|
static void bdi_writeout_fraction(struct backing_dev_info *bdi,
|
long *numerator, long *denominator)
|
long *numerator, long *denominator)
|
{
|
{
|
if (bdi_cap_writeback_dirty(bdi)) {
|
if (bdi_cap_writeback_dirty(bdi)) {
|
prop_fraction_percpu(&vm_completions, &bdi->completions,
|
prop_fraction_percpu(&vm_completions, &bdi->completions,
|
numerator, denominator);
|
numerator, denominator);
|
} else {
|
} else {
|
*numerator = 0;
|
*numerator = 0;
|
*denominator = 1;
|
*denominator = 1;
|
}
|
}
|
}
|
}
|
|
|
/*
|
/*
|
* Clip the earned share of dirty pages to that which is actually available.
|
* Clip the earned share of dirty pages to that which is actually available.
|
* This avoids exceeding the total dirty_limit when the floating averages
|
* This avoids exceeding the total dirty_limit when the floating averages
|
* fluctuate too quickly.
|
* fluctuate too quickly.
|
*/
|
*/
|
static void
|
static void
|
clip_bdi_dirty_limit(struct backing_dev_info *bdi, long dirty, long *pbdi_dirty)
|
clip_bdi_dirty_limit(struct backing_dev_info *bdi, long dirty, long *pbdi_dirty)
|
{
|
{
|
long avail_dirty;
|
long avail_dirty;
|
|
|
avail_dirty = dirty -
|
avail_dirty = dirty -
|
(global_page_state(NR_FILE_DIRTY) +
|
(global_page_state(NR_FILE_DIRTY) +
|
global_page_state(NR_WRITEBACK) +
|
global_page_state(NR_WRITEBACK) +
|
global_page_state(NR_UNSTABLE_NFS));
|
global_page_state(NR_UNSTABLE_NFS));
|
|
|
if (avail_dirty < 0)
|
if (avail_dirty < 0)
|
avail_dirty = 0;
|
avail_dirty = 0;
|
|
|
avail_dirty += bdi_stat(bdi, BDI_RECLAIMABLE) +
|
avail_dirty += bdi_stat(bdi, BDI_RECLAIMABLE) +
|
bdi_stat(bdi, BDI_WRITEBACK);
|
bdi_stat(bdi, BDI_WRITEBACK);
|
|
|
*pbdi_dirty = min(*pbdi_dirty, avail_dirty);
|
*pbdi_dirty = min(*pbdi_dirty, avail_dirty);
|
}
|
}
|
|
|
static inline void task_dirties_fraction(struct task_struct *tsk,
|
static inline void task_dirties_fraction(struct task_struct *tsk,
|
long *numerator, long *denominator)
|
long *numerator, long *denominator)
|
{
|
{
|
prop_fraction_single(&vm_dirties, &tsk->dirties,
|
prop_fraction_single(&vm_dirties, &tsk->dirties,
|
numerator, denominator);
|
numerator, denominator);
|
}
|
}
|
|
|
/*
|
/*
|
* scale the dirty limit
|
* scale the dirty limit
|
*
|
*
|
* task specific dirty limit:
|
* task specific dirty limit:
|
*
|
*
|
* dirty -= (dirty/8) * p_{t}
|
* dirty -= (dirty/8) * p_{t}
|
*/
|
*/
|
void task_dirty_limit(struct task_struct *tsk, long *pdirty)
|
void task_dirty_limit(struct task_struct *tsk, long *pdirty)
|
{
|
{
|
long numerator, denominator;
|
long numerator, denominator;
|
long dirty = *pdirty;
|
long dirty = *pdirty;
|
u64 inv = dirty >> 3;
|
u64 inv = dirty >> 3;
|
|
|
task_dirties_fraction(tsk, &numerator, &denominator);
|
task_dirties_fraction(tsk, &numerator, &denominator);
|
inv *= numerator;
|
inv *= numerator;
|
do_div(inv, denominator);
|
do_div(inv, denominator);
|
|
|
dirty -= inv;
|
dirty -= inv;
|
if (dirty < *pdirty/2)
|
if (dirty < *pdirty/2)
|
dirty = *pdirty/2;
|
dirty = *pdirty/2;
|
|
|
*pdirty = dirty;
|
*pdirty = dirty;
|
}
|
}
|
|
|
/*
|
/*
|
* Work out the current dirty-memory clamping and background writeout
|
* Work out the current dirty-memory clamping and background writeout
|
* thresholds.
|
* thresholds.
|
*
|
*
|
* The main aim here is to lower them aggressively if there is a lot of mapped
|
* The main aim here is to lower them aggressively if there is a lot of mapped
|
* memory around. To avoid stressing page reclaim with lots of unreclaimable
|
* memory around. To avoid stressing page reclaim with lots of unreclaimable
|
* pages. It is better to clamp down on writers than to start swapping, and
|
* pages. It is better to clamp down on writers than to start swapping, and
|
* performing lots of scanning.
|
* performing lots of scanning.
|
*
|
*
|
* We only allow 1/2 of the currently-unmapped memory to be dirtied.
|
* We only allow 1/2 of the currently-unmapped memory to be dirtied.
|
*
|
*
|
* We don't permit the clamping level to fall below 5% - that is getting rather
|
* We don't permit the clamping level to fall below 5% - that is getting rather
|
* excessive.
|
* excessive.
|
*
|
*
|
* We make sure that the background writeout level is below the adjusted
|
* We make sure that the background writeout level is below the adjusted
|
* clamping level.
|
* clamping level.
|
*/
|
*/
|
|
|
static unsigned long highmem_dirtyable_memory(unsigned long total)
|
static unsigned long highmem_dirtyable_memory(unsigned long total)
|
{
|
{
|
#ifdef CONFIG_HIGHMEM
|
#ifdef CONFIG_HIGHMEM
|
int node;
|
int node;
|
unsigned long x = 0;
|
unsigned long x = 0;
|
|
|
for_each_node_state(node, N_HIGH_MEMORY) {
|
for_each_node_state(node, N_HIGH_MEMORY) {
|
struct zone *z =
|
struct zone *z =
|
&NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
|
&NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
|
|
|
x += zone_page_state(z, NR_FREE_PAGES)
|
x += zone_page_state(z, NR_FREE_PAGES)
|
+ zone_page_state(z, NR_INACTIVE)
|
+ zone_page_state(z, NR_INACTIVE)
|
+ zone_page_state(z, NR_ACTIVE);
|
+ zone_page_state(z, NR_ACTIVE);
|
}
|
}
|
/*
|
/*
|
* Make sure that the number of highmem pages is never larger
|
* Make sure that the number of highmem pages is never larger
|
* than the number of the total dirtyable memory. This can only
|
* than the number of the total dirtyable memory. This can only
|
* occur in very strange VM situations but we want to make sure
|
* occur in very strange VM situations but we want to make sure
|
* that this does not occur.
|
* that this does not occur.
|
*/
|
*/
|
return min(x, total);
|
return min(x, total);
|
#else
|
#else
|
return 0;
|
return 0;
|
#endif
|
#endif
|
}
|
}
|
|
|
static unsigned long determine_dirtyable_memory(void)
|
static unsigned long determine_dirtyable_memory(void)
|
{
|
{
|
unsigned long x;
|
unsigned long x;
|
|
|
x = global_page_state(NR_FREE_PAGES)
|
x = global_page_state(NR_FREE_PAGES)
|
+ global_page_state(NR_INACTIVE)
|
+ global_page_state(NR_INACTIVE)
|
+ global_page_state(NR_ACTIVE);
|
+ global_page_state(NR_ACTIVE);
|
x -= highmem_dirtyable_memory(x);
|
x -= highmem_dirtyable_memory(x);
|
return x + 1; /* Ensure that we never return 0 */
|
return x + 1; /* Ensure that we never return 0 */
|
}
|
}
|
|
|
static void
|
static void
|
get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
|
get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
|
struct backing_dev_info *bdi)
|
struct backing_dev_info *bdi)
|
{
|
{
|
int background_ratio; /* Percentages */
|
int background_ratio; /* Percentages */
|
int dirty_ratio;
|
int dirty_ratio;
|
long background;
|
long background;
|
long dirty;
|
long dirty;
|
unsigned long available_memory = determine_dirtyable_memory();
|
unsigned long available_memory = determine_dirtyable_memory();
|
struct task_struct *tsk;
|
struct task_struct *tsk;
|
|
|
dirty_ratio = vm_dirty_ratio;
|
dirty_ratio = vm_dirty_ratio;
|
if (dirty_ratio < 5)
|
if (dirty_ratio < 5)
|
dirty_ratio = 5;
|
dirty_ratio = 5;
|
|
|
background_ratio = dirty_background_ratio;
|
background_ratio = dirty_background_ratio;
|
if (background_ratio >= dirty_ratio)
|
if (background_ratio >= dirty_ratio)
|
background_ratio = dirty_ratio / 2;
|
background_ratio = dirty_ratio / 2;
|
|
|
background = (background_ratio * available_memory) / 100;
|
background = (background_ratio * available_memory) / 100;
|
dirty = (dirty_ratio * available_memory) / 100;
|
dirty = (dirty_ratio * available_memory) / 100;
|
tsk = current;
|
tsk = current;
|
if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
|
if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
|
background += background / 4;
|
background += background / 4;
|
dirty += dirty / 4;
|
dirty += dirty / 4;
|
}
|
}
|
*pbackground = background;
|
*pbackground = background;
|
*pdirty = dirty;
|
*pdirty = dirty;
|
|
|
if (bdi) {
|
if (bdi) {
|
u64 bdi_dirty = dirty;
|
u64 bdi_dirty = dirty;
|
long numerator, denominator;
|
long numerator, denominator;
|
|
|
/*
|
/*
|
* Calculate this BDI's share of the dirty ratio.
|
* Calculate this BDI's share of the dirty ratio.
|
*/
|
*/
|
bdi_writeout_fraction(bdi, &numerator, &denominator);
|
bdi_writeout_fraction(bdi, &numerator, &denominator);
|
|
|
bdi_dirty *= numerator;
|
bdi_dirty *= numerator;
|
do_div(bdi_dirty, denominator);
|
do_div(bdi_dirty, denominator);
|
|
|
*pbdi_dirty = bdi_dirty;
|
*pbdi_dirty = bdi_dirty;
|
clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty);
|
clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty);
|
task_dirty_limit(current, pbdi_dirty);
|
task_dirty_limit(current, pbdi_dirty);
|
}
|
}
|
}
|
}
|
|
|
/*
|
/*
|
* balance_dirty_pages() must be called by processes which are generating dirty
|
* balance_dirty_pages() must be called by processes which are generating dirty
|
* data. It looks at the number of dirty pages in the machine and will force
|
* data. It looks at the number of dirty pages in the machine and will force
|
* the caller to perform writeback if the system is over `vm_dirty_ratio'.
|
* the caller to perform writeback if the system is over `vm_dirty_ratio'.
|
* If we're over `background_thresh' then pdflush is woken to perform some
|
* If we're over `background_thresh' then pdflush is woken to perform some
|
* writeout.
|
* writeout.
|
*/
|
*/
|
static void balance_dirty_pages(struct address_space *mapping)
|
static void balance_dirty_pages(struct address_space *mapping)
|
{
|
{
|
long nr_reclaimable, bdi_nr_reclaimable;
|
long nr_reclaimable, bdi_nr_reclaimable;
|
long nr_writeback, bdi_nr_writeback;
|
long nr_writeback, bdi_nr_writeback;
|
long background_thresh;
|
long background_thresh;
|
long dirty_thresh;
|
long dirty_thresh;
|
long bdi_thresh;
|
long bdi_thresh;
|
unsigned long pages_written = 0;
|
unsigned long pages_written = 0;
|
unsigned long write_chunk = sync_writeback_pages();
|
unsigned long write_chunk = sync_writeback_pages();
|
|
|
struct backing_dev_info *bdi = mapping->backing_dev_info;
|
struct backing_dev_info *bdi = mapping->backing_dev_info;
|
|
|
for (;;) {
|
for (;;) {
|
struct writeback_control wbc = {
|
struct writeback_control wbc = {
|
.bdi = bdi,
|
.bdi = bdi,
|
.sync_mode = WB_SYNC_NONE,
|
.sync_mode = WB_SYNC_NONE,
|
.older_than_this = NULL,
|
.older_than_this = NULL,
|
.nr_to_write = write_chunk,
|
.nr_to_write = write_chunk,
|
.range_cyclic = 1,
|
.range_cyclic = 1,
|
};
|
};
|
|
|
get_dirty_limits(&background_thresh, &dirty_thresh,
|
get_dirty_limits(&background_thresh, &dirty_thresh,
|
&bdi_thresh, bdi);
|
&bdi_thresh, bdi);
|
|
|
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
|
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
|
global_page_state(NR_UNSTABLE_NFS);
|
global_page_state(NR_UNSTABLE_NFS);
|
nr_writeback = global_page_state(NR_WRITEBACK);
|
nr_writeback = global_page_state(NR_WRITEBACK);
|
|
|
bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
|
bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
|
bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
|
bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
|
|
|
if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh)
|
if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh)
|
break;
|
break;
|
|
|
/*
|
/*
|
* Throttle it only when the background writeback cannot
|
* Throttle it only when the background writeback cannot
|
* catch-up. This avoids (excessively) small writeouts
|
* catch-up. This avoids (excessively) small writeouts
|
* when the bdi limits are ramping up.
|
* when the bdi limits are ramping up.
|
*/
|
*/
|
if (nr_reclaimable + nr_writeback <
|
if (nr_reclaimable + nr_writeback <
|
(background_thresh + dirty_thresh) / 2)
|
(background_thresh + dirty_thresh) / 2)
|
break;
|
break;
|
|
|
if (!bdi->dirty_exceeded)
|
if (!bdi->dirty_exceeded)
|
bdi->dirty_exceeded = 1;
|
bdi->dirty_exceeded = 1;
|
|
|
/* Note: nr_reclaimable denotes nr_dirty + nr_unstable.
|
/* Note: nr_reclaimable denotes nr_dirty + nr_unstable.
|
* Unstable writes are a feature of certain networked
|
* Unstable writes are a feature of certain networked
|
* filesystems (i.e. NFS) in which data may have been
|
* filesystems (i.e. NFS) in which data may have been
|
* written to the server's write cache, but has not yet
|
* written to the server's write cache, but has not yet
|
* been flushed to permanent storage.
|
* been flushed to permanent storage.
|
*/
|
*/
|
if (bdi_nr_reclaimable) {
|
if (bdi_nr_reclaimable) {
|
writeback_inodes(&wbc);
|
writeback_inodes(&wbc);
|
pages_written += write_chunk - wbc.nr_to_write;
|
pages_written += write_chunk - wbc.nr_to_write;
|
get_dirty_limits(&background_thresh, &dirty_thresh,
|
get_dirty_limits(&background_thresh, &dirty_thresh,
|
&bdi_thresh, bdi);
|
&bdi_thresh, bdi);
|
}
|
}
|
|
|
/*
|
/*
|
* In order to avoid the stacked BDI deadlock we need
|
* In order to avoid the stacked BDI deadlock we need
|
* to ensure we accurately count the 'dirty' pages when
|
* to ensure we accurately count the 'dirty' pages when
|
* the threshold is low.
|
* the threshold is low.
|
*
|
*
|
* Otherwise it would be possible to get thresh+n pages
|
* Otherwise it would be possible to get thresh+n pages
|
* reported dirty, even though there are thresh-m pages
|
* reported dirty, even though there are thresh-m pages
|
* actually dirty; with m+n sitting in the percpu
|
* actually dirty; with m+n sitting in the percpu
|
* deltas.
|
* deltas.
|
*/
|
*/
|
if (bdi_thresh < 2*bdi_stat_error(bdi)) {
|
if (bdi_thresh < 2*bdi_stat_error(bdi)) {
|
bdi_nr_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE);
|
bdi_nr_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE);
|
bdi_nr_writeback = bdi_stat_sum(bdi, BDI_WRITEBACK);
|
bdi_nr_writeback = bdi_stat_sum(bdi, BDI_WRITEBACK);
|
} else if (bdi_nr_reclaimable) {
|
} else if (bdi_nr_reclaimable) {
|
bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
|
bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
|
bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
|
bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
|
}
|
}
|
|
|
if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh)
|
if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh)
|
break;
|
break;
|
if (pages_written >= write_chunk)
|
if (pages_written >= write_chunk)
|
break; /* We've done our duty */
|
break; /* We've done our duty */
|
|
|
congestion_wait(WRITE, HZ/10);
|
congestion_wait(WRITE, HZ/10);
|
}
|
}
|
|
|
if (bdi_nr_reclaimable + bdi_nr_writeback < bdi_thresh &&
|
if (bdi_nr_reclaimable + bdi_nr_writeback < bdi_thresh &&
|
bdi->dirty_exceeded)
|
bdi->dirty_exceeded)
|
bdi->dirty_exceeded = 0;
|
bdi->dirty_exceeded = 0;
|
|
|
if (writeback_in_progress(bdi))
|
if (writeback_in_progress(bdi))
|
return; /* pdflush is already working this queue */
|
return; /* pdflush is already working this queue */
|
|
|
/*
|
/*
|
* In laptop mode, we wait until hitting the higher threshold before
|
* In laptop mode, we wait until hitting the higher threshold before
|
* starting background writeout, and then write out all the way down
|
* starting background writeout, and then write out all the way down
|
* to the lower threshold. So slow writers cause minimal disk activity.
|
* to the lower threshold. So slow writers cause minimal disk activity.
|
*
|
*
|
* In normal mode, we start background writeout at the lower
|
* In normal mode, we start background writeout at the lower
|
* background_thresh, to keep the amount of dirty memory low.
|
* background_thresh, to keep the amount of dirty memory low.
|
*/
|
*/
|
if ((laptop_mode && pages_written) ||
|
if ((laptop_mode && pages_written) ||
|
(!laptop_mode && (global_page_state(NR_FILE_DIRTY)
|
(!laptop_mode && (global_page_state(NR_FILE_DIRTY)
|
+ global_page_state(NR_UNSTABLE_NFS)
|
+ global_page_state(NR_UNSTABLE_NFS)
|
> background_thresh)))
|
> background_thresh)))
|
pdflush_operation(background_writeout, 0);
|
pdflush_operation(background_writeout, 0);
|
}
|
}
|
|
|
void set_page_dirty_balance(struct page *page, int page_mkwrite)
|
void set_page_dirty_balance(struct page *page, int page_mkwrite)
|
{
|
{
|
if (set_page_dirty(page) || page_mkwrite) {
|
if (set_page_dirty(page) || page_mkwrite) {
|
struct address_space *mapping = page_mapping(page);
|
struct address_space *mapping = page_mapping(page);
|
|
|
if (mapping)
|
if (mapping)
|
balance_dirty_pages_ratelimited(mapping);
|
balance_dirty_pages_ratelimited(mapping);
|
}
|
}
|
}
|
}
|
|
|
/**
|
/**
|
* balance_dirty_pages_ratelimited_nr - balance dirty memory state
|
* balance_dirty_pages_ratelimited_nr - balance dirty memory state
|
* @mapping: address_space which was dirtied
|
* @mapping: address_space which was dirtied
|
* @nr_pages_dirtied: number of pages which the caller has just dirtied
|
* @nr_pages_dirtied: number of pages which the caller has just dirtied
|
*
|
*
|
* Processes which are dirtying memory should call in here once for each page
|
* Processes which are dirtying memory should call in here once for each page
|
* which was newly dirtied. The function will periodically check the system's
|
* which was newly dirtied. The function will periodically check the system's
|
* dirty state and will initiate writeback if needed.
|
* dirty state and will initiate writeback if needed.
|
*
|
*
|
* On really big machines, get_writeback_state is expensive, so try to avoid
|
* On really big machines, get_writeback_state is expensive, so try to avoid
|
* calling it too often (ratelimiting). But once we're over the dirty memory
|
* calling it too often (ratelimiting). But once we're over the dirty memory
|
* limit we decrease the ratelimiting by a lot, to prevent individual processes
|
* limit we decrease the ratelimiting by a lot, to prevent individual processes
|
* from overshooting the limit by (ratelimit_pages) each.
|
* from overshooting the limit by (ratelimit_pages) each.
|
*/
|
*/
|
void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
|
void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
|
unsigned long nr_pages_dirtied)
|
unsigned long nr_pages_dirtied)
|
{
|
{
|
static DEFINE_PER_CPU(unsigned long, ratelimits) = 0;
|
static DEFINE_PER_CPU(unsigned long, ratelimits) = 0;
|
unsigned long ratelimit;
|
unsigned long ratelimit;
|
unsigned long *p;
|
unsigned long *p;
|
|
|
ratelimit = ratelimit_pages;
|
ratelimit = ratelimit_pages;
|
if (mapping->backing_dev_info->dirty_exceeded)
|
if (mapping->backing_dev_info->dirty_exceeded)
|
ratelimit = 8;
|
ratelimit = 8;
|
|
|
/*
|
/*
|
* Check the rate limiting. Also, we do not want to throttle real-time
|
* Check the rate limiting. Also, we do not want to throttle real-time
|
* tasks in balance_dirty_pages(). Period.
|
* tasks in balance_dirty_pages(). Period.
|
*/
|
*/
|
preempt_disable();
|
preempt_disable();
|
p = &__get_cpu_var(ratelimits);
|
p = &__get_cpu_var(ratelimits);
|
*p += nr_pages_dirtied;
|
*p += nr_pages_dirtied;
|
if (unlikely(*p >= ratelimit)) {
|
if (unlikely(*p >= ratelimit)) {
|
*p = 0;
|
*p = 0;
|
preempt_enable();
|
preempt_enable();
|
balance_dirty_pages(mapping);
|
balance_dirty_pages(mapping);
|
return;
|
return;
|
}
|
}
|
preempt_enable();
|
preempt_enable();
|
}
|
}
|
EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr);
|
EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr);
|
|
|
void throttle_vm_writeout(gfp_t gfp_mask)
|
void throttle_vm_writeout(gfp_t gfp_mask)
|
{
|
{
|
long background_thresh;
|
long background_thresh;
|
long dirty_thresh;
|
long dirty_thresh;
|
|
|
for ( ; ; ) {
|
for ( ; ; ) {
|
get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
|
get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
|
|
|
/*
|
/*
|
* Boost the allowable dirty threshold a bit for page
|
* Boost the allowable dirty threshold a bit for page
|
* allocators so they don't get DoS'ed by heavy writers
|
* allocators so they don't get DoS'ed by heavy writers
|
*/
|
*/
|
dirty_thresh += dirty_thresh / 10; /* wheeee... */
|
dirty_thresh += dirty_thresh / 10; /* wheeee... */
|
|
|
if (global_page_state(NR_UNSTABLE_NFS) +
|
if (global_page_state(NR_UNSTABLE_NFS) +
|
global_page_state(NR_WRITEBACK) <= dirty_thresh)
|
global_page_state(NR_WRITEBACK) <= dirty_thresh)
|
break;
|
break;
|
congestion_wait(WRITE, HZ/10);
|
congestion_wait(WRITE, HZ/10);
|
|
|
/*
|
/*
|
* The caller might hold locks which can prevent IO completion
|
* The caller might hold locks which can prevent IO completion
|
* or progress in the filesystem. So we cannot just sit here
|
* or progress in the filesystem. So we cannot just sit here
|
* waiting for IO to complete.
|
* waiting for IO to complete.
|
*/
|
*/
|
if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO))
|
if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO))
|
break;
|
break;
|
}
|
}
|
}
|
}
|
|
|
/*
|
/*
|
* writeback at least _min_pages, and keep writing until the amount of dirty
|
* writeback at least _min_pages, and keep writing until the amount of dirty
|
* memory is less than the background threshold, or until we're all clean.
|
* memory is less than the background threshold, or until we're all clean.
|
*/
|
*/
|
static void background_writeout(unsigned long _min_pages)
|
static void background_writeout(unsigned long _min_pages)
|
{
|
{
|
long min_pages = _min_pages;
|
long min_pages = _min_pages;
|
struct writeback_control wbc = {
|
struct writeback_control wbc = {
|
.bdi = NULL,
|
.bdi = NULL,
|
.sync_mode = WB_SYNC_NONE,
|
.sync_mode = WB_SYNC_NONE,
|
.older_than_this = NULL,
|
.older_than_this = NULL,
|
.nr_to_write = 0,
|
.nr_to_write = 0,
|
.nonblocking = 1,
|
.nonblocking = 1,
|
.range_cyclic = 1,
|
.range_cyclic = 1,
|
};
|
};
|
|
|
for ( ; ; ) {
|
for ( ; ; ) {
|
long background_thresh;
|
long background_thresh;
|
long dirty_thresh;
|
long dirty_thresh;
|
|
|
get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
|
get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
|
if (global_page_state(NR_FILE_DIRTY) +
|
if (global_page_state(NR_FILE_DIRTY) +
|
global_page_state(NR_UNSTABLE_NFS) < background_thresh
|
global_page_state(NR_UNSTABLE_NFS) < background_thresh
|
&& min_pages <= 0)
|
&& min_pages <= 0)
|
break;
|
break;
|
wbc.encountered_congestion = 0;
|
wbc.encountered_congestion = 0;
|
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
|
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
|
wbc.pages_skipped = 0;
|
wbc.pages_skipped = 0;
|
writeback_inodes(&wbc);
|
writeback_inodes(&wbc);
|
min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
|
min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
|
if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
|
if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
|
/* Wrote less than expected */
|
/* Wrote less than expected */
|
congestion_wait(WRITE, HZ/10);
|
congestion_wait(WRITE, HZ/10);
|
if (!wbc.encountered_congestion)
|
if (!wbc.encountered_congestion)
|
break;
|
break;
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
/*
|
/*
|
* Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
|
* Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
|
* the whole world. Returns 0 if a pdflush thread was dispatched. Returns
|
* the whole world. Returns 0 if a pdflush thread was dispatched. Returns
|
* -1 if all pdflush threads were busy.
|
* -1 if all pdflush threads were busy.
|
*/
|
*/
|
int wakeup_pdflush(long nr_pages)
|
int wakeup_pdflush(long nr_pages)
|
{
|
{
|
if (nr_pages == 0)
|
if (nr_pages == 0)
|
nr_pages = global_page_state(NR_FILE_DIRTY) +
|
nr_pages = global_page_state(NR_FILE_DIRTY) +
|
global_page_state(NR_UNSTABLE_NFS);
|
global_page_state(NR_UNSTABLE_NFS);
|
return pdflush_operation(background_writeout, nr_pages);
|
return pdflush_operation(background_writeout, nr_pages);
|
}
|
}
|
|
|
static void wb_timer_fn(unsigned long unused);
|
static void wb_timer_fn(unsigned long unused);
|
static void laptop_timer_fn(unsigned long unused);
|
static void laptop_timer_fn(unsigned long unused);
|
|
|
static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0);
|
static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0);
|
static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0);
|
static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0);
|
|
|
/*
|
/*
|
* Periodic writeback of "old" data.
|
* Periodic writeback of "old" data.
|
*
|
*
|
* Define "old": the first time one of an inode's pages is dirtied, we mark the
|
* Define "old": the first time one of an inode's pages is dirtied, we mark the
|
* dirtying-time in the inode's address_space. So this periodic writeback code
|
* dirtying-time in the inode's address_space. So this periodic writeback code
|
* just walks the superblock inode list, writing back any inodes which are
|
* just walks the superblock inode list, writing back any inodes which are
|
* older than a specific point in time.
|
* older than a specific point in time.
|
*
|
*
|
* Try to run once per dirty_writeback_interval. But if a writeback event
|
* Try to run once per dirty_writeback_interval. But if a writeback event
|
* takes longer than a dirty_writeback_interval interval, then leave a
|
* takes longer than a dirty_writeback_interval interval, then leave a
|
* one-second gap.
|
* one-second gap.
|
*
|
*
|
* older_than_this takes precedence over nr_to_write. So we'll only write back
|
* older_than_this takes precedence over nr_to_write. So we'll only write back
|
* all dirty pages if they are all attached to "old" mappings.
|
* all dirty pages if they are all attached to "old" mappings.
|
*/
|
*/
|
static void wb_kupdate(unsigned long arg)
|
static void wb_kupdate(unsigned long arg)
|
{
|
{
|
unsigned long oldest_jif;
|
unsigned long oldest_jif;
|
unsigned long start_jif;
|
unsigned long start_jif;
|
unsigned long next_jif;
|
unsigned long next_jif;
|
long nr_to_write;
|
long nr_to_write;
|
struct writeback_control wbc = {
|
struct writeback_control wbc = {
|
.bdi = NULL,
|
.bdi = NULL,
|
.sync_mode = WB_SYNC_NONE,
|
.sync_mode = WB_SYNC_NONE,
|
.older_than_this = &oldest_jif,
|
.older_than_this = &oldest_jif,
|
.nr_to_write = 0,
|
.nr_to_write = 0,
|
.nonblocking = 1,
|
.nonblocking = 1,
|
.for_kupdate = 1,
|
.for_kupdate = 1,
|
.range_cyclic = 1,
|
.range_cyclic = 1,
|
};
|
};
|
|
|
sync_supers();
|
sync_supers();
|
|
|
oldest_jif = jiffies - dirty_expire_interval;
|
oldest_jif = jiffies - dirty_expire_interval;
|
start_jif = jiffies;
|
start_jif = jiffies;
|
next_jif = start_jif + dirty_writeback_interval;
|
next_jif = start_jif + dirty_writeback_interval;
|
nr_to_write = global_page_state(NR_FILE_DIRTY) +
|
nr_to_write = global_page_state(NR_FILE_DIRTY) +
|
global_page_state(NR_UNSTABLE_NFS) +
|
global_page_state(NR_UNSTABLE_NFS) +
|
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
|
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
|
while (nr_to_write > 0) {
|
while (nr_to_write > 0) {
|
wbc.encountered_congestion = 0;
|
wbc.encountered_congestion = 0;
|
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
|
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
|
writeback_inodes(&wbc);
|
writeback_inodes(&wbc);
|
if (wbc.nr_to_write > 0) {
|
if (wbc.nr_to_write > 0) {
|
if (wbc.encountered_congestion)
|
if (wbc.encountered_congestion)
|
congestion_wait(WRITE, HZ/10);
|
congestion_wait(WRITE, HZ/10);
|
else
|
else
|
break; /* All the old data is written */
|
break; /* All the old data is written */
|
}
|
}
|
nr_to_write -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
|
nr_to_write -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
|
}
|
}
|
if (time_before(next_jif, jiffies + HZ))
|
if (time_before(next_jif, jiffies + HZ))
|
next_jif = jiffies + HZ;
|
next_jif = jiffies + HZ;
|
if (dirty_writeback_interval)
|
if (dirty_writeback_interval)
|
mod_timer(&wb_timer, next_jif);
|
mod_timer(&wb_timer, next_jif);
|
}
|
}
|
|
|
/*
|
/*
|
* sysctl handler for /proc/sys/vm/dirty_writeback_centisecs
|
* sysctl handler for /proc/sys/vm/dirty_writeback_centisecs
|
*/
|
*/
|
int dirty_writeback_centisecs_handler(ctl_table *table, int write,
|
int dirty_writeback_centisecs_handler(ctl_table *table, int write,
|
struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
|
struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
|
{
|
{
|
proc_dointvec_userhz_jiffies(table, write, file, buffer, length, ppos);
|
proc_dointvec_userhz_jiffies(table, write, file, buffer, length, ppos);
|
if (dirty_writeback_interval)
|
if (dirty_writeback_interval)
|
mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
|
mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
|
else
|
else
|
del_timer(&wb_timer);
|
del_timer(&wb_timer);
|
return 0;
|
return 0;
|
}
|
}
|
|
|
static void wb_timer_fn(unsigned long unused)
|
static void wb_timer_fn(unsigned long unused)
|
{
|
{
|
if (pdflush_operation(wb_kupdate, 0) < 0)
|
if (pdflush_operation(wb_kupdate, 0) < 0)
|
mod_timer(&wb_timer, jiffies + HZ); /* delay 1 second */
|
mod_timer(&wb_timer, jiffies + HZ); /* delay 1 second */
|
}
|
}
|
|
|
static void laptop_flush(unsigned long unused)
|
static void laptop_flush(unsigned long unused)
|
{
|
{
|
sys_sync();
|
sys_sync();
|
}
|
}
|
|
|
static void laptop_timer_fn(unsigned long unused)
|
static void laptop_timer_fn(unsigned long unused)
|
{
|
{
|
pdflush_operation(laptop_flush, 0);
|
pdflush_operation(laptop_flush, 0);
|
}
|
}
|
|
|
/*
|
/*
|
* We've spun up the disk and we're in laptop mode: schedule writeback
|
* We've spun up the disk and we're in laptop mode: schedule writeback
|
* of all dirty data a few seconds from now. If the flush is already scheduled
|
* of all dirty data a few seconds from now. If the flush is already scheduled
|
* then push it back - the user is still using the disk.
|
* then push it back - the user is still using the disk.
|
*/
|
*/
|
void laptop_io_completion(void)
|
void laptop_io_completion(void)
|
{
|
{
|
mod_timer(&laptop_mode_wb_timer, jiffies + laptop_mode);
|
mod_timer(&laptop_mode_wb_timer, jiffies + laptop_mode);
|
}
|
}
|
|
|
/*
|
/*
|
* We're in laptop mode and we've just synced. The sync's writes will have
|
* We're in laptop mode and we've just synced. The sync's writes will have
|
* caused another writeback to be scheduled by laptop_io_completion.
|
* caused another writeback to be scheduled by laptop_io_completion.
|
* Nothing needs to be written back anymore, so we unschedule the writeback.
|
* Nothing needs to be written back anymore, so we unschedule the writeback.
|
*/
|
*/
|
void laptop_sync_completion(void)
|
void laptop_sync_completion(void)
|
{
|
{
|
del_timer(&laptop_mode_wb_timer);
|
del_timer(&laptop_mode_wb_timer);
|
}
|
}
|
|
|
/*
|
/*
|
* If ratelimit_pages is too high then we can get into dirty-data overload
|
* If ratelimit_pages is too high then we can get into dirty-data overload
|
* if a large number of processes all perform writes at the same time.
|
* if a large number of processes all perform writes at the same time.
|
* If it is too low then SMP machines will call the (expensive)
|
* If it is too low then SMP machines will call the (expensive)
|
* get_writeback_state too often.
|
* get_writeback_state too often.
|
*
|
*
|
* Here we set ratelimit_pages to a level which ensures that when all CPUs are
|
* Here we set ratelimit_pages to a level which ensures that when all CPUs are
|
* dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory
|
* dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory
|
* thresholds before writeback cuts in.
|
* thresholds before writeback cuts in.
|
*
|
*
|
* But the limit should not be set too high. Because it also controls the
|
* But the limit should not be set too high. Because it also controls the
|
* amount of memory which the balance_dirty_pages() caller has to write back.
|
* amount of memory which the balance_dirty_pages() caller has to write back.
|
* If this is too large then the caller will block on the IO queue all the
|
* If this is too large then the caller will block on the IO queue all the
|
* time. So limit it to four megabytes - the balance_dirty_pages() caller
|
* time. So limit it to four megabytes - the balance_dirty_pages() caller
|
* will write six megabyte chunks, max.
|
* will write six megabyte chunks, max.
|
*/
|
*/
|
|
|
void writeback_set_ratelimit(void)
|
void writeback_set_ratelimit(void)
|
{
|
{
|
ratelimit_pages = vm_total_pages / (num_online_cpus() * 32);
|
ratelimit_pages = vm_total_pages / (num_online_cpus() * 32);
|
if (ratelimit_pages < 16)
|
if (ratelimit_pages < 16)
|
ratelimit_pages = 16;
|
ratelimit_pages = 16;
|
if (ratelimit_pages * PAGE_CACHE_SIZE > 4096 * 1024)
|
if (ratelimit_pages * PAGE_CACHE_SIZE > 4096 * 1024)
|
ratelimit_pages = (4096 * 1024) / PAGE_CACHE_SIZE;
|
ratelimit_pages = (4096 * 1024) / PAGE_CACHE_SIZE;
|
}
|
}
|
|
|
static int __cpuinit
|
static int __cpuinit
|
ratelimit_handler(struct notifier_block *self, unsigned long u, void *v)
|
ratelimit_handler(struct notifier_block *self, unsigned long u, void *v)
|
{
|
{
|
writeback_set_ratelimit();
|
writeback_set_ratelimit();
|
return NOTIFY_DONE;
|
return NOTIFY_DONE;
|
}
|
}
|
|
|
static struct notifier_block __cpuinitdata ratelimit_nb = {
|
static struct notifier_block __cpuinitdata ratelimit_nb = {
|
.notifier_call = ratelimit_handler,
|
.notifier_call = ratelimit_handler,
|
.next = NULL,
|
.next = NULL,
|
};
|
};
|
|
|
/*
|
/*
|
* Called early on to tune the page writeback dirty limits.
|
* Called early on to tune the page writeback dirty limits.
|
*
|
*
|
* We used to scale dirty pages according to how total memory
|
* We used to scale dirty pages according to how total memory
|
* related to pages that could be allocated for buffers (by
|
* related to pages that could be allocated for buffers (by
|
* comparing nr_free_buffer_pages() to vm_total_pages.
|
* comparing nr_free_buffer_pages() to vm_total_pages.
|
*
|
*
|
* However, that was when we used "dirty_ratio" to scale with
|
* However, that was when we used "dirty_ratio" to scale with
|
* all memory, and we don't do that any more. "dirty_ratio"
|
* all memory, and we don't do that any more. "dirty_ratio"
|
* is now applied to total non-HIGHPAGE memory (by subtracting
|
* is now applied to total non-HIGHPAGE memory (by subtracting
|
* totalhigh_pages from vm_total_pages), and as such we can't
|
* totalhigh_pages from vm_total_pages), and as such we can't
|
* get into the old insane situation any more where we had
|
* get into the old insane situation any more where we had
|
* large amounts of dirty pages compared to a small amount of
|
* large amounts of dirty pages compared to a small amount of
|
* non-HIGHMEM memory.
|
* non-HIGHMEM memory.
|
*
|
*
|
* But we might still want to scale the dirty_ratio by how
|
* But we might still want to scale the dirty_ratio by how
|
* much memory the box has..
|
* much memory the box has..
|
*/
|
*/
|
void __init page_writeback_init(void)
|
void __init page_writeback_init(void)
|
{
|
{
|
int shift;
|
int shift;
|
|
|
mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
|
mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
|
writeback_set_ratelimit();
|
writeback_set_ratelimit();
|
register_cpu_notifier(&ratelimit_nb);
|
register_cpu_notifier(&ratelimit_nb);
|
|
|
shift = calc_period_shift();
|
shift = calc_period_shift();
|
prop_descriptor_init(&vm_completions, shift);
|
prop_descriptor_init(&vm_completions, shift);
|
prop_descriptor_init(&vm_dirties, shift);
|
prop_descriptor_init(&vm_dirties, shift);
|
}
|
}
|
|
|
/**
|
/**
|
* write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
|
* write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
|
* @mapping: address space structure to write
|
* @mapping: address space structure to write
|
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
|
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
|
* @writepage: function called for each page
|
* @writepage: function called for each page
|
* @data: data passed to writepage function
|
* @data: data passed to writepage function
|
*
|
*
|
* If a page is already under I/O, write_cache_pages() skips it, even
|
* If a page is already under I/O, write_cache_pages() skips it, even
|
* if it's dirty. This is desirable behaviour for memory-cleaning writeback,
|
* if it's dirty. This is desirable behaviour for memory-cleaning writeback,
|
* but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
|
* but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
|
* and msync() need to guarantee that all the data which was dirty at the time
|
* and msync() need to guarantee that all the data which was dirty at the time
|
* the call was made get new I/O started against them. If wbc->sync_mode is
|
* the call was made get new I/O started against them. If wbc->sync_mode is
|
* WB_SYNC_ALL then we were called for data integrity and we must wait for
|
* WB_SYNC_ALL then we were called for data integrity and we must wait for
|
* existing IO to complete.
|
* existing IO to complete.
|
*/
|
*/
|
int write_cache_pages(struct address_space *mapping,
|
int write_cache_pages(struct address_space *mapping,
|
struct writeback_control *wbc, writepage_t writepage,
|
struct writeback_control *wbc, writepage_t writepage,
|
void *data)
|
void *data)
|
{
|
{
|
struct backing_dev_info *bdi = mapping->backing_dev_info;
|
struct backing_dev_info *bdi = mapping->backing_dev_info;
|
int ret = 0;
|
int ret = 0;
|
int done = 0;
|
int done = 0;
|
struct pagevec pvec;
|
struct pagevec pvec;
|
int nr_pages;
|
int nr_pages;
|
pgoff_t index;
|
pgoff_t index;
|
pgoff_t end; /* Inclusive */
|
pgoff_t end; /* Inclusive */
|
int scanned = 0;
|
int scanned = 0;
|
int range_whole = 0;
|
int range_whole = 0;
|
|
|
if (wbc->nonblocking && bdi_write_congested(bdi)) {
|
if (wbc->nonblocking && bdi_write_congested(bdi)) {
|
wbc->encountered_congestion = 1;
|
wbc->encountered_congestion = 1;
|
return 0;
|
return 0;
|
}
|
}
|
|
|
pagevec_init(&pvec, 0);
|
pagevec_init(&pvec, 0);
|
if (wbc->range_cyclic) {
|
if (wbc->range_cyclic) {
|
index = mapping->writeback_index; /* Start from prev offset */
|
index = mapping->writeback_index; /* Start from prev offset */
|
end = -1;
|
end = -1;
|
} else {
|
} else {
|
index = wbc->range_start >> PAGE_CACHE_SHIFT;
|
index = wbc->range_start >> PAGE_CACHE_SHIFT;
|
end = wbc->range_end >> PAGE_CACHE_SHIFT;
|
end = wbc->range_end >> PAGE_CACHE_SHIFT;
|
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
|
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
|
range_whole = 1;
|
range_whole = 1;
|
scanned = 1;
|
scanned = 1;
|
}
|
}
|
retry:
|
retry:
|
while (!done && (index <= end) &&
|
while (!done && (index <= end) &&
|
(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
|
(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
|
PAGECACHE_TAG_DIRTY,
|
PAGECACHE_TAG_DIRTY,
|
min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
|
min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
|
unsigned i;
|
unsigned i;
|
|
|
scanned = 1;
|
scanned = 1;
|
for (i = 0; i < nr_pages; i++) {
|
for (i = 0; i < nr_pages; i++) {
|
struct page *page = pvec.pages[i];
|
struct page *page = pvec.pages[i];
|
|
|
/*
|
/*
|
* At this point we hold neither mapping->tree_lock nor
|
* At this point we hold neither mapping->tree_lock nor
|
* lock on the page itself: the page may be truncated or
|
* lock on the page itself: the page may be truncated or
|
* invalidated (changing page->mapping to NULL), or even
|
* invalidated (changing page->mapping to NULL), or even
|
* swizzled back from swapper_space to tmpfs file
|
* swizzled back from swapper_space to tmpfs file
|
* mapping
|
* mapping
|
*/
|
*/
|
lock_page(page);
|
lock_page(page);
|
|
|
if (unlikely(page->mapping != mapping)) {
|
if (unlikely(page->mapping != mapping)) {
|
unlock_page(page);
|
unlock_page(page);
|
continue;
|
continue;
|
}
|
}
|
|
|
if (!wbc->range_cyclic && page->index > end) {
|
if (!wbc->range_cyclic && page->index > end) {
|
done = 1;
|
done = 1;
|
unlock_page(page);
|
unlock_page(page);
|
continue;
|
continue;
|
}
|
}
|
|
|
if (wbc->sync_mode != WB_SYNC_NONE)
|
if (wbc->sync_mode != WB_SYNC_NONE)
|
wait_on_page_writeback(page);
|
wait_on_page_writeback(page);
|
|
|
if (PageWriteback(page) ||
|
if (PageWriteback(page) ||
|
!clear_page_dirty_for_io(page)) {
|
!clear_page_dirty_for_io(page)) {
|
unlock_page(page);
|
unlock_page(page);
|
continue;
|
continue;
|
}
|
}
|
|
|
ret = (*writepage)(page, wbc, data);
|
ret = (*writepage)(page, wbc, data);
|
|
|
if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
|
if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
|
unlock_page(page);
|
unlock_page(page);
|
ret = 0;
|
ret = 0;
|
}
|
}
|
if (ret || (--(wbc->nr_to_write) <= 0))
|
if (ret || (--(wbc->nr_to_write) <= 0))
|
done = 1;
|
done = 1;
|
if (wbc->nonblocking && bdi_write_congested(bdi)) {
|
if (wbc->nonblocking && bdi_write_congested(bdi)) {
|
wbc->encountered_congestion = 1;
|
wbc->encountered_congestion = 1;
|
done = 1;
|
done = 1;
|
}
|
}
|
}
|
}
|
pagevec_release(&pvec);
|
pagevec_release(&pvec);
|
cond_resched();
|
cond_resched();
|
}
|
}
|
if (!scanned && !done) {
|
if (!scanned && !done) {
|
/*
|
/*
|
* We hit the last page and there is more work to be done: wrap
|
* We hit the last page and there is more work to be done: wrap
|
* back to the start of the file
|
* back to the start of the file
|
*/
|
*/
|
scanned = 1;
|
scanned = 1;
|
index = 0;
|
index = 0;
|
goto retry;
|
goto retry;
|
}
|
}
|
if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
|
if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
|
mapping->writeback_index = index;
|
mapping->writeback_index = index;
|
return ret;
|
return ret;
|
}
|
}
|
EXPORT_SYMBOL(write_cache_pages);
|
EXPORT_SYMBOL(write_cache_pages);
|
|
|
/*
|
/*
|
* Function used by generic_writepages to call the real writepage
|
* Function used by generic_writepages to call the real writepage
|
* function and set the mapping flags on error
|
* function and set the mapping flags on error
|
*/
|
*/
|
static int __writepage(struct page *page, struct writeback_control *wbc,
|
static int __writepage(struct page *page, struct writeback_control *wbc,
|
void *data)
|
void *data)
|
{
|
{
|
struct address_space *mapping = data;
|
struct address_space *mapping = data;
|
int ret = mapping->a_ops->writepage(page, wbc);
|
int ret = mapping->a_ops->writepage(page, wbc);
|
mapping_set_error(mapping, ret);
|
mapping_set_error(mapping, ret);
|
return ret;
|
return ret;
|
}
|
}
|
|
|
/**
|
/**
|
* generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
|
* generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
|
* @mapping: address space structure to write
|
* @mapping: address space structure to write
|
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
|
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
|
*
|
*
|
* This is a library function, which implements the writepages()
|
* This is a library function, which implements the writepages()
|
* address_space_operation.
|
* address_space_operation.
|
*/
|
*/
|
int generic_writepages(struct address_space *mapping,
|
int generic_writepages(struct address_space *mapping,
|
struct writeback_control *wbc)
|
struct writeback_control *wbc)
|
{
|
{
|
/* deal with chardevs and other special file */
|
/* deal with chardevs and other special file */
|
if (!mapping->a_ops->writepage)
|
if (!mapping->a_ops->writepage)
|
return 0;
|
return 0;
|
|
|
return write_cache_pages(mapping, wbc, __writepage, mapping);
|
return write_cache_pages(mapping, wbc, __writepage, mapping);
|
}
|
}
|
|
|
EXPORT_SYMBOL(generic_writepages);
|
EXPORT_SYMBOL(generic_writepages);
|
|
|
int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
|
int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
|
{
|
{
|
int ret;
|
int ret;
|
|
|
if (wbc->nr_to_write <= 0)
|
if (wbc->nr_to_write <= 0)
|
return 0;
|
return 0;
|
wbc->for_writepages = 1;
|
wbc->for_writepages = 1;
|
if (mapping->a_ops->writepages)
|
if (mapping->a_ops->writepages)
|
ret = mapping->a_ops->writepages(mapping, wbc);
|
ret = mapping->a_ops->writepages(mapping, wbc);
|
else
|
else
|
ret = generic_writepages(mapping, wbc);
|
ret = generic_writepages(mapping, wbc);
|
wbc->for_writepages = 0;
|
wbc->for_writepages = 0;
|
return ret;
|
return ret;
|
}
|
}
|
|
|
/**
|
/**
|
* write_one_page - write out a single page and optionally wait on I/O
|
* write_one_page - write out a single page and optionally wait on I/O
|
* @page: the page to write
|
* @page: the page to write
|
* @wait: if true, wait on writeout
|
* @wait: if true, wait on writeout
|
*
|
*
|
* The page must be locked by the caller and will be unlocked upon return.
|
* The page must be locked by the caller and will be unlocked upon return.
|
*
|
*
|
* write_one_page() returns a negative error code if I/O failed.
|
* write_one_page() returns a negative error code if I/O failed.
|
*/
|
*/
|
int write_one_page(struct page *page, int wait)
|
int write_one_page(struct page *page, int wait)
|
{
|
{
|
struct address_space *mapping = page->mapping;
|
struct address_space *mapping = page->mapping;
|
int ret = 0;
|
int ret = 0;
|
struct writeback_control wbc = {
|
struct writeback_control wbc = {
|
.sync_mode = WB_SYNC_ALL,
|
.sync_mode = WB_SYNC_ALL,
|
.nr_to_write = 1,
|
.nr_to_write = 1,
|
};
|
};
|
|
|
BUG_ON(!PageLocked(page));
|
BUG_ON(!PageLocked(page));
|
|
|
if (wait)
|
if (wait)
|
wait_on_page_writeback(page);
|
wait_on_page_writeback(page);
|
|
|
if (clear_page_dirty_for_io(page)) {
|
if (clear_page_dirty_for_io(page)) {
|
page_cache_get(page);
|
page_cache_get(page);
|
ret = mapping->a_ops->writepage(page, &wbc);
|
ret = mapping->a_ops->writepage(page, &wbc);
|
if (ret == 0 && wait) {
|
if (ret == 0 && wait) {
|
wait_on_page_writeback(page);
|
wait_on_page_writeback(page);
|
if (PageError(page))
|
if (PageError(page))
|
ret = -EIO;
|
ret = -EIO;
|
}
|
}
|
page_cache_release(page);
|
page_cache_release(page);
|
} else {
|
} else {
|
unlock_page(page);
|
unlock_page(page);
|
}
|
}
|
return ret;
|
return ret;
|
}
|
}
|
EXPORT_SYMBOL(write_one_page);
|
EXPORT_SYMBOL(write_one_page);
|
|
|
/*
|
/*
|
* For address_spaces which do not use buffers nor write back.
|
* For address_spaces which do not use buffers nor write back.
|
*/
|
*/
|
int __set_page_dirty_no_writeback(struct page *page)
|
int __set_page_dirty_no_writeback(struct page *page)
|
{
|
{
|
if (!PageDirty(page))
|
if (!PageDirty(page))
|
SetPageDirty(page);
|
SetPageDirty(page);
|
return 0;
|
return 0;
|
}
|
}
|
|
|
/*
|
/*
|
* For address_spaces which do not use buffers. Just tag the page as dirty in
|
* For address_spaces which do not use buffers. Just tag the page as dirty in
|
* its radix tree.
|
* its radix tree.
|
*
|
*
|
* This is also used when a single buffer is being dirtied: we want to set the
|
* This is also used when a single buffer is being dirtied: we want to set the
|
* page dirty in that case, but not all the buffers. This is a "bottom-up"
|
* page dirty in that case, but not all the buffers. This is a "bottom-up"
|
* dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying.
|
* dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying.
|
*
|
*
|
* Most callers have locked the page, which pins the address_space in memory.
|
* Most callers have locked the page, which pins the address_space in memory.
|
* But zap_pte_range() does not lock the page, however in that case the
|
* But zap_pte_range() does not lock the page, however in that case the
|
* mapping is pinned by the vma's ->vm_file reference.
|
* mapping is pinned by the vma's ->vm_file reference.
|
*
|
*
|
* We take care to handle the case where the page was truncated from the
|
* We take care to handle the case where the page was truncated from the
|
* mapping by re-checking page_mapping() inside tree_lock.
|
* mapping by re-checking page_mapping() inside tree_lock.
|
*/
|
*/
|
int __set_page_dirty_nobuffers(struct page *page)
|
int __set_page_dirty_nobuffers(struct page *page)
|
{
|
{
|
if (!TestSetPageDirty(page)) {
|
if (!TestSetPageDirty(page)) {
|
struct address_space *mapping = page_mapping(page);
|
struct address_space *mapping = page_mapping(page);
|
struct address_space *mapping2;
|
struct address_space *mapping2;
|
|
|
if (!mapping)
|
if (!mapping)
|
return 1;
|
return 1;
|
|
|
write_lock_irq(&mapping->tree_lock);
|
write_lock_irq(&mapping->tree_lock);
|
mapping2 = page_mapping(page);
|
mapping2 = page_mapping(page);
|
if (mapping2) { /* Race with truncate? */
|
if (mapping2) { /* Race with truncate? */
|
BUG_ON(mapping2 != mapping);
|
BUG_ON(mapping2 != mapping);
|
WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
|
WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
|
if (mapping_cap_account_dirty(mapping)) {
|
if (mapping_cap_account_dirty(mapping)) {
|
__inc_zone_page_state(page, NR_FILE_DIRTY);
|
__inc_zone_page_state(page, NR_FILE_DIRTY);
|
__inc_bdi_stat(mapping->backing_dev_info,
|
__inc_bdi_stat(mapping->backing_dev_info,
|
BDI_RECLAIMABLE);
|
BDI_RECLAIMABLE);
|
task_io_account_write(PAGE_CACHE_SIZE);
|
task_io_account_write(PAGE_CACHE_SIZE);
|
}
|
}
|
radix_tree_tag_set(&mapping->page_tree,
|
radix_tree_tag_set(&mapping->page_tree,
|
page_index(page), PAGECACHE_TAG_DIRTY);
|
page_index(page), PAGECACHE_TAG_DIRTY);
|
}
|
}
|
write_unlock_irq(&mapping->tree_lock);
|
write_unlock_irq(&mapping->tree_lock);
|
if (mapping->host) {
|
if (mapping->host) {
|
/* !PageAnon && !swapper_space */
|
/* !PageAnon && !swapper_space */
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
}
|
}
|
return 1;
|
return 1;
|
}
|
}
|
return 0;
|
return 0;
|
}
|
}
|
EXPORT_SYMBOL(__set_page_dirty_nobuffers);
|
EXPORT_SYMBOL(__set_page_dirty_nobuffers);
|
|
|
/*
|
/*
|
* When a writepage implementation decides that it doesn't want to write this
|
* When a writepage implementation decides that it doesn't want to write this
|
* page for some reason, it should redirty the locked page via
|
* page for some reason, it should redirty the locked page via
|
* redirty_page_for_writepage() and it should then unlock the page and return 0
|
* redirty_page_for_writepage() and it should then unlock the page and return 0
|
*/
|
*/
|
int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page)
|
int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page)
|
{
|
{
|
wbc->pages_skipped++;
|
wbc->pages_skipped++;
|
return __set_page_dirty_nobuffers(page);
|
return __set_page_dirty_nobuffers(page);
|
}
|
}
|
EXPORT_SYMBOL(redirty_page_for_writepage);
|
EXPORT_SYMBOL(redirty_page_for_writepage);
|
|
|
/*
|
/*
|
* If the mapping doesn't provide a set_page_dirty a_op, then
|
* If the mapping doesn't provide a set_page_dirty a_op, then
|
* just fall through and assume that it wants buffer_heads.
|
* just fall through and assume that it wants buffer_heads.
|
*/
|
*/
|
static int __set_page_dirty(struct page *page)
|
static int __set_page_dirty(struct page *page)
|
{
|
{
|
struct address_space *mapping = page_mapping(page);
|
struct address_space *mapping = page_mapping(page);
|
|
|
if (likely(mapping)) {
|
if (likely(mapping)) {
|
int (*spd)(struct page *) = mapping->a_ops->set_page_dirty;
|
int (*spd)(struct page *) = mapping->a_ops->set_page_dirty;
|
#ifdef CONFIG_BLOCK
|
#ifdef CONFIG_BLOCK
|
if (!spd)
|
if (!spd)
|
spd = __set_page_dirty_buffers;
|
spd = __set_page_dirty_buffers;
|
#endif
|
#endif
|
return (*spd)(page);
|
return (*spd)(page);
|
}
|
}
|
if (!PageDirty(page)) {
|
if (!PageDirty(page)) {
|
if (!TestSetPageDirty(page))
|
if (!TestSetPageDirty(page))
|
return 1;
|
return 1;
|
}
|
}
|
return 0;
|
return 0;
|
}
|
}
|
|
|
int fastcall set_page_dirty(struct page *page)
|
int fastcall set_page_dirty(struct page *page)
|
{
|
{
|
int ret = __set_page_dirty(page);
|
int ret = __set_page_dirty(page);
|
if (ret)
|
if (ret)
|
task_dirty_inc(current);
|
task_dirty_inc(current);
|
return ret;
|
return ret;
|
}
|
}
|
EXPORT_SYMBOL(set_page_dirty);
|
EXPORT_SYMBOL(set_page_dirty);
|
|
|
/*
|
/*
|
* set_page_dirty() is racy if the caller has no reference against
|
* set_page_dirty() is racy if the caller has no reference against
|
* page->mapping->host, and if the page is unlocked. This is because another
|
* page->mapping->host, and if the page is unlocked. This is because another
|
* CPU could truncate the page off the mapping and then free the mapping.
|
* CPU could truncate the page off the mapping and then free the mapping.
|
*
|
*
|
* Usually, the page _is_ locked, or the caller is a user-space process which
|
* Usually, the page _is_ locked, or the caller is a user-space process which
|
* holds a reference on the inode by having an open file.
|
* holds a reference on the inode by having an open file.
|
*
|
*
|
* In other cases, the page should be locked before running set_page_dirty().
|
* In other cases, the page should be locked before running set_page_dirty().
|
*/
|
*/
|
int set_page_dirty_lock(struct page *page)
|
int set_page_dirty_lock(struct page *page)
|
{
|
{
|
int ret;
|
int ret;
|
|
|
lock_page_nosync(page);
|
lock_page_nosync(page);
|
ret = set_page_dirty(page);
|
ret = set_page_dirty(page);
|
unlock_page(page);
|
unlock_page(page);
|
return ret;
|
return ret;
|
}
|
}
|
EXPORT_SYMBOL(set_page_dirty_lock);
|
EXPORT_SYMBOL(set_page_dirty_lock);
|
|
|
/*
|
/*
|
* Clear a page's dirty flag, while caring for dirty memory accounting.
|
* Clear a page's dirty flag, while caring for dirty memory accounting.
|
* Returns true if the page was previously dirty.
|
* Returns true if the page was previously dirty.
|
*
|
*
|
* This is for preparing to put the page under writeout. We leave the page
|
* This is for preparing to put the page under writeout. We leave the page
|
* tagged as dirty in the radix tree so that a concurrent write-for-sync
|
* tagged as dirty in the radix tree so that a concurrent write-for-sync
|
* can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage
|
* can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage
|
* implementation will run either set_page_writeback() or set_page_dirty(),
|
* implementation will run either set_page_writeback() or set_page_dirty(),
|
* at which stage we bring the page's dirty flag and radix-tree dirty tag
|
* at which stage we bring the page's dirty flag and radix-tree dirty tag
|
* back into sync.
|
* back into sync.
|
*
|
*
|
* This incoherency between the page's dirty flag and radix-tree tag is
|
* This incoherency between the page's dirty flag and radix-tree tag is
|
* unfortunate, but it only exists while the page is locked.
|
* unfortunate, but it only exists while the page is locked.
|
*/
|
*/
|
int clear_page_dirty_for_io(struct page *page)
|
int clear_page_dirty_for_io(struct page *page)
|
{
|
{
|
struct address_space *mapping = page_mapping(page);
|
struct address_space *mapping = page_mapping(page);
|
|
|
BUG_ON(!PageLocked(page));
|
BUG_ON(!PageLocked(page));
|
|
|
ClearPageReclaim(page);
|
ClearPageReclaim(page);
|
if (mapping && mapping_cap_account_dirty(mapping)) {
|
if (mapping && mapping_cap_account_dirty(mapping)) {
|
/*
|
/*
|
* Yes, Virginia, this is indeed insane.
|
* Yes, Virginia, this is indeed insane.
|
*
|
*
|
* We use this sequence to make sure that
|
* We use this sequence to make sure that
|
* (a) we account for dirty stats properly
|
* (a) we account for dirty stats properly
|
* (b) we tell the low-level filesystem to
|
* (b) we tell the low-level filesystem to
|
* mark the whole page dirty if it was
|
* mark the whole page dirty if it was
|
* dirty in a pagetable. Only to then
|
* dirty in a pagetable. Only to then
|
* (c) clean the page again and return 1 to
|
* (c) clean the page again and return 1 to
|
* cause the writeback.
|
* cause the writeback.
|
*
|
*
|
* This way we avoid all nasty races with the
|
* This way we avoid all nasty races with the
|
* dirty bit in multiple places and clearing
|
* dirty bit in multiple places and clearing
|
* them concurrently from different threads.
|
* them concurrently from different threads.
|
*
|
*
|
* Note! Normally the "set_page_dirty(page)"
|
* Note! Normally the "set_page_dirty(page)"
|
* has no effect on the actual dirty bit - since
|
* has no effect on the actual dirty bit - since
|
* that will already usually be set. But we
|
* that will already usually be set. But we
|
* need the side effects, and it can help us
|
* need the side effects, and it can help us
|
* avoid races.
|
* avoid races.
|
*
|
*
|
* We basically use the page "master dirty bit"
|
* We basically use the page "master dirty bit"
|
* as a serialization point for all the different
|
* as a serialization point for all the different
|
* threads doing their things.
|
* threads doing their things.
|
*/
|
*/
|
if (page_mkclean(page))
|
if (page_mkclean(page))
|
set_page_dirty(page);
|
set_page_dirty(page);
|
/*
|
/*
|
* We carefully synchronise fault handlers against
|
* We carefully synchronise fault handlers against
|
* installing a dirty pte and marking the page dirty
|
* installing a dirty pte and marking the page dirty
|
* at this point. We do this by having them hold the
|
* at this point. We do this by having them hold the
|
* page lock at some point after installing their
|
* page lock at some point after installing their
|
* pte, but before marking the page dirty.
|
* pte, but before marking the page dirty.
|
* Pages are always locked coming in here, so we get
|
* Pages are always locked coming in here, so we get
|
* the desired exclusion. See mm/memory.c:do_wp_page()
|
* the desired exclusion. See mm/memory.c:do_wp_page()
|
* for more comments.
|
* for more comments.
|
*/
|
*/
|
if (TestClearPageDirty(page)) {
|
if (TestClearPageDirty(page)) {
|
dec_zone_page_state(page, NR_FILE_DIRTY);
|
dec_zone_page_state(page, NR_FILE_DIRTY);
|
dec_bdi_stat(mapping->backing_dev_info,
|
dec_bdi_stat(mapping->backing_dev_info,
|
BDI_RECLAIMABLE);
|
BDI_RECLAIMABLE);
|
return 1;
|
return 1;
|
}
|
}
|
return 0;
|
return 0;
|
}
|
}
|
return TestClearPageDirty(page);
|
return TestClearPageDirty(page);
|
}
|
}
|
EXPORT_SYMBOL(clear_page_dirty_for_io);
|
EXPORT_SYMBOL(clear_page_dirty_for_io);
|
|
|
int test_clear_page_writeback(struct page *page)
|
int test_clear_page_writeback(struct page *page)
|
{
|
{
|
struct address_space *mapping = page_mapping(page);
|
struct address_space *mapping = page_mapping(page);
|
int ret;
|
int ret;
|
|
|
if (mapping) {
|
if (mapping) {
|
struct backing_dev_info *bdi = mapping->backing_dev_info;
|
struct backing_dev_info *bdi = mapping->backing_dev_info;
|
unsigned long flags;
|
unsigned long flags;
|
|
|
write_lock_irqsave(&mapping->tree_lock, flags);
|
write_lock_irqsave(&mapping->tree_lock, flags);
|
ret = TestClearPageWriteback(page);
|
ret = TestClearPageWriteback(page);
|
if (ret) {
|
if (ret) {
|
radix_tree_tag_clear(&mapping->page_tree,
|
radix_tree_tag_clear(&mapping->page_tree,
|
page_index(page),
|
page_index(page),
|
PAGECACHE_TAG_WRITEBACK);
|
PAGECACHE_TAG_WRITEBACK);
|
if (bdi_cap_writeback_dirty(bdi)) {
|
if (bdi_cap_writeback_dirty(bdi)) {
|
__dec_bdi_stat(bdi, BDI_WRITEBACK);
|
__dec_bdi_stat(bdi, BDI_WRITEBACK);
|
__bdi_writeout_inc(bdi);
|
__bdi_writeout_inc(bdi);
|
}
|
}
|
}
|
}
|
write_unlock_irqrestore(&mapping->tree_lock, flags);
|
write_unlock_irqrestore(&mapping->tree_lock, flags);
|
} else {
|
} else {
|
ret = TestClearPageWriteback(page);
|
ret = TestClearPageWriteback(page);
|
}
|
}
|
if (ret)
|
if (ret)
|
dec_zone_page_state(page, NR_WRITEBACK);
|
dec_zone_page_state(page, NR_WRITEBACK);
|
return ret;
|
return ret;
|
}
|
}
|
|
|
int test_set_page_writeback(struct page *page)
|
int test_set_page_writeback(struct page *page)
|
{
|
{
|
struct address_space *mapping = page_mapping(page);
|
struct address_space *mapping = page_mapping(page);
|
int ret;
|
int ret;
|
|
|
if (mapping) {
|
if (mapping) {
|
struct backing_dev_info *bdi = mapping->backing_dev_info;
|
struct backing_dev_info *bdi = mapping->backing_dev_info;
|
unsigned long flags;
|
unsigned long flags;
|
|
|
write_lock_irqsave(&mapping->tree_lock, flags);
|
write_lock_irqsave(&mapping->tree_lock, flags);
|
ret = TestSetPageWriteback(page);
|
ret = TestSetPageWriteback(page);
|
if (!ret) {
|
if (!ret) {
|
radix_tree_tag_set(&mapping->page_tree,
|
radix_tree_tag_set(&mapping->page_tree,
|
page_index(page),
|
page_index(page),
|
PAGECACHE_TAG_WRITEBACK);
|
PAGECACHE_TAG_WRITEBACK);
|
if (bdi_cap_writeback_dirty(bdi))
|
if (bdi_cap_writeback_dirty(bdi))
|
__inc_bdi_stat(bdi, BDI_WRITEBACK);
|
__inc_bdi_stat(bdi, BDI_WRITEBACK);
|
}
|
}
|
if (!PageDirty(page))
|
if (!PageDirty(page))
|
radix_tree_tag_clear(&mapping->page_tree,
|
radix_tree_tag_clear(&mapping->page_tree,
|
page_index(page),
|
page_index(page),
|
PAGECACHE_TAG_DIRTY);
|
PAGECACHE_TAG_DIRTY);
|
write_unlock_irqrestore(&mapping->tree_lock, flags);
|
write_unlock_irqrestore(&mapping->tree_lock, flags);
|
} else {
|
} else {
|
ret = TestSetPageWriteback(page);
|
ret = TestSetPageWriteback(page);
|
}
|
}
|
if (!ret)
|
if (!ret)
|
inc_zone_page_state(page, NR_WRITEBACK);
|
inc_zone_page_state(page, NR_WRITEBACK);
|
return ret;
|
return ret;
|
|
|
}
|
}
|
EXPORT_SYMBOL(test_set_page_writeback);
|
EXPORT_SYMBOL(test_set_page_writeback);
|
|
|
/*
|
/*
|
* Return true if any of the pages in the mapping are marked with the
|
* Return true if any of the pages in the mapping are marked with the
|
* passed tag.
|
* passed tag.
|
*/
|
*/
|
int mapping_tagged(struct address_space *mapping, int tag)
|
int mapping_tagged(struct address_space *mapping, int tag)
|
{
|
{
|
int ret;
|
int ret;
|
rcu_read_lock();
|
rcu_read_lock();
|
ret = radix_tree_tagged(&mapping->page_tree, tag);
|
ret = radix_tree_tagged(&mapping->page_tree, tag);
|
rcu_read_unlock();
|
rcu_read_unlock();
|
return ret;
|
return ret;
|
}
|
}
|
EXPORT_SYMBOL(mapping_tagged);
|
EXPORT_SYMBOL(mapping_tagged);
|
|
|
