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linux-sg2042
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quota: Convert quota statistics to generic percpu_counter 

Generic per-cpu counter has some memory overhead but it is negligible for
modern systems and embedded systems compile without quota support.  And code
reuse is a good thing. This patch should fix complain from preemptive kernels
which was introduced by dde9588853.

[Jan Kara: Fixed patch to work on 32-bit archs as well]

Reported-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Dmitry Monakhov 2010-05-26 23:21:58 +02:00 committed by Jan Kara
parent 1513b02c8b
commit f32764bd2b
2 changed files with 17 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
fs/quota/dquot.c
View File

@ -228,10 +228,6 @@ static struct hlist_head *dquot_hash;
struct dqstats dqstats;
EXPORT_SYMBOL(dqstats);
#ifdef CONFIG_SMP
struct dqstats *dqstats_pcpu;
EXPORT_SYMBOL(dqstats_pcpu);
#endif
static qsize_t inode_get_rsv_space(struct inode *inode);
static void __dquot_initialize(struct inode *inode, int type);
@ -676,27 +672,10 @@ static void prune_dqcache(int count)
}
}
static int dqstats_read(unsigned int type)
{
int count = 0;
#ifdef CONFIG_SMP
int cpu;
for_each_possible_cpu(cpu)
count += per_cpu_ptr(dqstats_pcpu, cpu)->stat[type];
/* Statistics reading is racy, but absolute accuracy isn't required */
if (count < 0)
count = 0;
#else
count = dqstats.stat[type];
#endif
return count;
}
/*
* This is called from kswapd when we think we need some
* more memory
*/
static int shrink_dqcache_memory(int nr, gfp_t gfp_mask)
{
if (nr) {
@ -704,7 +683,9 @@ static int shrink_dqcache_memory(int nr, gfp_t gfp_mask)
prune_dqcache(nr);
spin_unlock(&dq_list_lock);
}
return (dqstats_read(DQST_FREE_DQUOTS)/100) * sysctl_vfs_cache_pressure;
return ((unsigned)
percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS])
/100) * sysctl_vfs_cache_pressure;
}
static struct shrinker dqcache_shrinker = {
@ -2497,11 +2478,11 @@ EXPORT_SYMBOL(dquot_quotactl_ops);
static int do_proc_dqstats(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
#ifdef CONFIG_SMP
/* Update global table */
unsigned int type = (int *)table->data - dqstats.stat;
dqstats.stat[type] = dqstats_read(type);
#endif
/* Update global table */
dqstats.stat[type] =
percpu_counter_sum_positive(&dqstats.counter[type]);
return proc_dointvec(table, write, buffer, lenp, ppos);
}
@ -2594,7 +2575,7 @@ static ctl_table sys_table[] = {
static int __init dquot_init(void)
{
int i;
int i, ret;
unsigned long nr_hash, order;
printk(KERN_NOTICE "VFS: Disk quotas %s\n", __DQUOT_VERSION__);
@ -2612,12 +2593,11 @@ static int __init dquot_init(void)
if (!dquot_hash)
panic("Cannot create dquot hash table");
#ifdef CONFIG_SMP
dqstats_pcpu = alloc_percpu(struct dqstats);
if (!dqstats_pcpu)
panic("Cannot create dquot stats table");
#endif
memset(&dqstats, 0, sizeof(struct dqstats));
for (i = 0; i < _DQST_DQSTAT_LAST; i++) {
ret = percpu_counter_init(&dqstats.counter[i], 0);
if (ret)
panic("Cannot create dquot stat counters");
}
/* Find power-of-two hlist_heads which can fit into allocation */
nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);

16
include/linux/quota.h
View File

@ -174,8 +174,7 @@ enum {
#include <linux/rwsem.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/percpu_counter.h>
#include <linux/dqblk_xfs.h>
#include <linux/dqblk_v1.h>
@ -254,6 +253,7 @@ enum {
struct dqstats {
int stat[_DQST_DQSTAT_LAST];
struct percpu_counter counter[_DQST_DQSTAT_LAST];
};
extern struct dqstats *dqstats_pcpu;
@ -261,20 +261,12 @@ extern struct dqstats dqstats;
static inline void dqstats_inc(unsigned int type)
{
#ifdef CONFIG_SMP
per_cpu_ptr(dqstats_pcpu, smp_processor_id())->stat[type]++;
#else
dqstats.stat[type]++;
#endif
percpu_counter_inc(&dqstats.counter[type]);
}
static inline void dqstats_dec(unsigned int type)
{
#ifdef CONFIG_SMP
per_cpu_ptr(dqstats_pcpu, smp_processor_id())->stat[type]--;
#else
dqstats.stat[type]--;
#endif
percpu_counter_dec(&dqstats.counter[type]);
}
#define DQ_MOD_B 0 /* dquot modified since read */