From f32764bd2bbb6ea003c158b1d276b4dc9f900348 Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Wed, 26 May 2010 23:21:58 +0200 Subject: [PATCH] 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 dde9588853b1bde. [Jan Kara: Fixed patch to work on 32-bit archs as well] Reported-by: Rafael J. Wysocki Signed-off-by: Dmitry Monakhov Signed-off-by: Jan Kara --- fs/quota/dquot.c | 46 ++++++++++++------------------------------- include/linux/quota.h | 16 ++++----------- 2 files changed, 17 insertions(+), 45 deletions(-) diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index 1ff91314b8a0..531dee651ef7 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -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); diff --git a/include/linux/quota.h b/include/linux/quota.h index 2789d07c37be..94c1f03b50eb 100644 --- a/include/linux/quota.h +++ b/include/linux/quota.h @@ -174,8 +174,7 @@ enum { #include #include #include -#include -#include +#include #include #include @@ -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 */ -- 2.39.2