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: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/include/linux/quota.h b/include/linux/quota.h
index b462916..cdfde10 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -174,6 +174,8 @@
#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 @@
return test_bit(DQF_INFO_DIRTY_B, &info->dqi_flags);
}
-struct dqstats {
- int lookups;
- int drops;
- int reads;
- int writes;
- int cache_hits;
- int allocated_dquots;
- int free_dquots;
- int syncs;
+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 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 */