Commit dde95888 authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Jan Kara
Browse files

quota: Make quota stat accounting lockless. 



Quota stats is mostly writable data structure. Let's alloc percpu
bucket for each value.

NOTE: dqstats_read() function is racy against dqstats_{inc,dec}
and may return inconsistent value. But this is ok since absolute
accuracy is not required.

Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent da8d1ba2

fs/quota/dquot.c

+68 −34
Original line number Diff line number Diff line
@@ -82,7 +82,7 @@ 


/*

 * There are three quota SMP locks. dq_list_lock protects all lists with quotas

 * and quota formats, dqstats structure containing statistics about the lists

 * and quota formats.

 * dq_data_lock protects data from dq_dqb and also mem_dqinfo structures and

 * also guards consistency of dquot->dq_dqb with inode->i_blocks, i_bytes.

 * i_blocks and i_bytes updates itself are guarded by i_lock acquired directly
@@ -228,6 +228,10 @@ 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);
@@ -275,7 +279,7 @@ static struct dquot *find_dquot(unsigned int hashent, struct super_block *sb, 
static inline void put_dquot_last(struct dquot *dquot)

{

	list_add_tail(&dquot->dq_free, &free_dquots);

	dqstats.free_dquots++;

	dqstats_inc(DQST_FREE_DQUOTS);

}



static inline void remove_free_dquot(struct dquot *dquot)
@@ -283,7 +287,7 @@ static inline void remove_free_dquot(struct dquot *dquot) 
	if (list_empty(&dquot->dq_free))

		return;

	list_del_init(&dquot->dq_free);

	dqstats.free_dquots--;

	dqstats_dec(DQST_FREE_DQUOTS);

}



static inline void put_inuse(struct dquot *dquot)
@@ -291,12 +295,12 @@ static inline void put_inuse(struct dquot *dquot) 
	/* We add to the back of inuse list so we don't have to restart

	 * when traversing this list and we block */

	list_add_tail(&dquot->dq_inuse, &inuse_list);

	dqstats.allocated_dquots++;

	dqstats_inc(DQST_ALLOC_DQUOTS);

}



static inline void remove_inuse(struct dquot *dquot)

{

	dqstats.allocated_dquots--;

	dqstats_dec(DQST_ALLOC_DQUOTS);

	list_del(&dquot->dq_inuse);

}

/*
@@ -561,8 +565,8 @@ int dquot_scan_active(struct super_block *sb, 
			continue;

		/* Now we have active dquot so we can just increase use count */

		atomic_inc(&dquot->dq_count);

		dqstats.lookups++;

		spin_unlock(&dq_list_lock);

		dqstats_inc(DQST_LOOKUPS);

		dqput(old_dquot);

		old_dquot = dquot;

		ret = fn(dquot, priv);
@@ -607,8 +611,8 @@ int vfs_quota_sync(struct super_block *sb, int type, int wait) 
 			 * holding reference so we can safely just increase

			 * use count */

			atomic_inc(&dquot->dq_count);

			dqstats.lookups++;

			spin_unlock(&dq_list_lock);

			dqstats_inc(DQST_LOOKUPS);

			sb->dq_op->write_dquot(dquot);

			dqput(dquot);

			spin_lock(&dq_list_lock);
@@ -620,9 +624,7 @@ int vfs_quota_sync(struct super_block *sb, int type, int wait) 
		if ((cnt == type || type == -1) && sb_has_quota_active(sb, cnt)

		    && info_dirty(&dqopt->info[cnt]))

			sb->dq_op->write_info(sb, cnt);

	spin_lock(&dq_list_lock);

	dqstats.syncs++;

	spin_unlock(&dq_list_lock);

	dqstats_inc(DQST_SYNCS);

	mutex_unlock(&dqopt->dqonoff_mutex);



	if (!wait || (sb_dqopt(sb)->flags & DQUOT_QUOTA_SYS_FILE))
@@ -674,6 +676,22 @@ 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
@@ -686,7 +704,7 @@ static int shrink_dqcache_memory(int nr, gfp_t gfp_mask) 
		prune_dqcache(nr);

		spin_unlock(&dq_list_lock);

	}

	return (dqstats.free_dquots / 100) * sysctl_vfs_cache_pressure;

	return (dqstats_read(DQST_FREE_DQUOTS)/100) * sysctl_vfs_cache_pressure;

}



static struct shrinker dqcache_shrinker = {
@@ -714,10 +732,7 @@ void dqput(struct dquot *dquot) 
		BUG();

	}

#endif

	

	spin_lock(&dq_list_lock);

	dqstats.drops++;

	spin_unlock(&dq_list_lock);

	dqstats_inc(DQST_DROPS);

we_slept:

	spin_lock(&dq_list_lock);

	if (atomic_read(&dquot->dq_count) > 1) {
@@ -834,15 +849,15 @@ struct dquot *dqget(struct super_block *sb, unsigned int id, int type) 
		put_inuse(dquot);

		/* hash it first so it can be found */

		insert_dquot_hash(dquot);

		dqstats.lookups++;

		spin_unlock(&dq_list_lock);

		dqstats_inc(DQST_LOOKUPS);

	} else {

		if (!atomic_read(&dquot->dq_count))

			remove_free_dquot(dquot);

		atomic_inc(&dquot->dq_count);

		dqstats.cache_hits++;

		dqstats.lookups++;

		spin_unlock(&dq_list_lock);

		dqstats_inc(DQST_CACHE_HITS);

		dqstats_inc(DQST_LOOKUPS);

	}

	/* Wait for dq_lock - after this we know that either dquot_release() is

	 * already finished or it will be canceled due to dq_count > 1 test */
@@ -2476,62 +2491,74 @@ const struct quotactl_ops vfs_quotactl_ops = { 
	.set_dqblk	= vfs_set_dqblk

};





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

	return proc_dointvec(table, write, buffer, lenp, ppos);

}



static ctl_table fs_dqstats_table[] = {

	{

		.procname	= "lookups",

		.data		= &dqstats.lookups,

		.data		= &dqstats.stat[DQST_LOOKUPS],

		.maxlen		= sizeof(int),

		.mode		= 0444,

		.proc_handler	= proc_dointvec,

		.proc_handler	= do_proc_dqstats,

	},

	{

		.procname	= "drops",

		.data		= &dqstats.drops,

		.data		= &dqstats.stat[DQST_DROPS],

		.maxlen		= sizeof(int),

		.mode		= 0444,

		.proc_handler	= proc_dointvec,

		.proc_handler	= do_proc_dqstats,

	},

	{

		.procname	= "reads",

		.data		= &dqstats.reads,

		.data		= &dqstats.stat[DQST_READS],

		.maxlen		= sizeof(int),

		.mode		= 0444,

		.proc_handler	= proc_dointvec,

		.proc_handler	= do_proc_dqstats,

	},

	{

		.procname	= "writes",

		.data		= &dqstats.writes,

		.data		= &dqstats.stat[DQST_WRITES],

		.maxlen		= sizeof(int),

		.mode		= 0444,

		.proc_handler	= proc_dointvec,

		.proc_handler	= do_proc_dqstats,

	},

	{

		.procname	= "cache_hits",

		.data		= &dqstats.cache_hits,

		.data		= &dqstats.stat[DQST_CACHE_HITS],

		.maxlen		= sizeof(int),

		.mode		= 0444,

		.proc_handler	= proc_dointvec,

		.proc_handler	= do_proc_dqstats,

	},

	{

		.procname	= "allocated_dquots",

		.data		= &dqstats.allocated_dquots,

		.data		= &dqstats.stat[DQST_ALLOC_DQUOTS],

		.maxlen		= sizeof(int),

		.mode		= 0444,

		.proc_handler	= proc_dointvec,

		.proc_handler	= do_proc_dqstats,

	},

	{

		.procname	= "free_dquots",

		.data		= &dqstats.free_dquots,

		.data		= &dqstats.stat[DQST_FREE_DQUOTS],

		.maxlen		= sizeof(int),

		.mode		= 0444,

		.proc_handler	= proc_dointvec,

		.proc_handler	= do_proc_dqstats,

	},

	{

		.procname	= "syncs",

		.data		= &dqstats.syncs,

		.data		= &dqstats.stat[DQST_SYNCS],

		.maxlen		= sizeof(int),

		.mode		= 0444,

		.proc_handler	= proc_dointvec,

		.proc_handler	= do_proc_dqstats,

	},

#ifdef CONFIG_PRINT_QUOTA_WARNING

	{
@@ -2583,6 +2610,13 @@ 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));



	/* Find power-of-two hlist_heads which can fit into allocation */

	nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);

	dq_hash_bits = 0;

fs/quota/quota_tree.c

+2 −2
Original line number Diff line number Diff line
@@ -384,7 +384,7 @@ int qtree_write_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot) 
	} else {

		ret = 0;

	}

	dqstats.writes++;

	dqstats_inc(DQST_WRITES);

	kfree(ddquot);



	return ret;
@@ -634,7 +634,7 @@ int qtree_read_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot) 
	spin_unlock(&dq_data_lock);

	kfree(ddquot);

out:

	dqstats.reads++;

	dqstats_inc(DQST_READS);

	return ret;

}

EXPORT_SYMBOL(qtree_read_dquot);

fs/quota/quota_v1.c

+2 −2
Original line number Diff line number Diff line
@@ -71,7 +71,7 @@ static int v1_read_dqblk(struct dquot *dquot) 
	    dquot->dq_dqb.dqb_ihardlimit == 0 &&

	    dquot->dq_dqb.dqb_isoftlimit == 0)

		set_bit(DQ_FAKE_B, &dquot->dq_flags);

	dqstats.reads++;

	dqstats_inc(DQST_READS);



	return 0;

}
@@ -104,7 +104,7 @@ static int v1_commit_dqblk(struct dquot *dquot) 
	ret = 0;



out:

	dqstats.writes++;

	dqstats_inc(DQST_WRITES);



	return ret;

}

include/linux/quota.h

+34 −8
Original line number Diff line number Diff line
@@ -174,6 +174,8 @@ enum { 
#include <linux/rwsem.h>

#include <linux/spinlock.h>

#include <linux/wait.h>

#include <linux/percpu.h>

#include <linux/smp.h>



#include <linux/dqblk_xfs.h>

#include <linux/dqblk_v1.h>
@@ -238,19 +240,43 @@ static inline int info_dirty(struct mem_dqinfo *info) 
	return test_bit(DQF_INFO_DIRTY_B, &info->dqi_flags);

}



enum {

	DQST_LOOKUPS,

	DQST_DROPS,

	DQST_READS,

	DQST_WRITES,

	DQST_CACHE_HITS,

	DQST_ALLOC_DQUOTS,

	DQST_FREE_DQUOTS,

	DQST_SYNCS,

	_DQST_DQSTAT_LAST

};



struct dqstats {

	int lookups;

	int drops;

	int reads;

	int writes;

	int cache_hits;

	int allocated_dquots;

	int free_dquots;

	int syncs;

	int stat[_DQST_DQSTAT_LAST];

};



extern struct dqstats *dqstats_pcpu;

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

}



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

}



#define DQ_MOD_B	0	/* dquot modified since read */

#define DQ_BLKS_B	1	/* uid/gid has been warned about blk limit */

#define DQ_INODES_B	2	/* uid/gid has been warned about inode limit */