nfsd: protect concurrent access to nfsd stats counters

nfsd stats counters can be updated by concurrent nfsd threads without any
protection.

Convert some nfsd_stats and nfsd_net struct members to use percpu counters.

The longest_chain* members of struct nfsd_net remain unprotected.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 69 insertions, 11 deletions

diff --git a/fs/nfsd/stats.h b/fs/nfsd/stats.h
index 5e3cdf21556a..87c3150c200f 100644
--- a/fs/nfsd/stats.h
+++ b/fs/nfsd/stats.h
@@ -8,27 +8,85 @@
 #define _NFSD_STATS_H
 
 #include <uapi/linux/nfsd/stats.h>
+#include <linux/percpu_counter.h>
 
 
-struct nfsd_stats {
-	unsigned int	rchits;		/* repcache hits */
-	unsigned int	rcmisses;	/* repcache hits */
-	unsigned int	rcnocache;	/* uncached reqs */
-	unsigned int	fh_stale;	/* FH stale error */
-	unsigned int	io_read;	/* bytes returned to read requests */
-	unsigned int	io_write;	/* bytes passed in write requests */
-	unsigned int	th_cnt;		/* number of available threads */
+enum {
+	NFSD_STATS_RC_HITS,		/* repcache hits */
+	NFSD_STATS_RC_MISSES,		/* repcache misses */
+	NFSD_STATS_RC_NOCACHE,		/* uncached reqs */
+	NFSD_STATS_FH_STALE,		/* FH stale error */
+	NFSD_STATS_IO_READ,		/* bytes returned to read requests */
+	NFSD_STATS_IO_WRITE,		/* bytes passed in write requests */
 #ifdef CONFIG_NFSD_V4
-	unsigned int	nfs4_opcount[LAST_NFS4_OP + 1];	/* count of individual nfsv4 operations */
+	NFSD_STATS_FIRST_NFS4_OP,	/* count of individual nfsv4 operations */
+	NFSD_STATS_LAST_NFS4_OP = NFSD_STATS_FIRST_NFS4_OP + LAST_NFS4_OP,
+#define NFSD_STATS_NFS4_OP(op)	(NFSD_STATS_FIRST_NFS4_OP + (op))
 #endif
+	NFSD_STATS_COUNTERS_NUM
+};
+
+struct nfsd_stats {
+	struct percpu_counter	counter[NFSD_STATS_COUNTERS_NUM];
 
+	/* Protected by nfsd_mutex */
+	unsigned int	th_cnt;		/* number of available threads */
 };
 
 
 extern struct nfsd_stats	nfsdstats;
+
 extern struct svc_stat		nfsd_svcstats;
 
-void	nfsd_stat_init(void);
-void	nfsd_stat_shutdown(void);
+int nfsd_percpu_counters_init(struct percpu_counter counters[], int num);
+void nfsd_percpu_counters_reset(struct percpu_counter counters[], int num);
+void nfsd_percpu_counters_destroy(struct percpu_counter counters[], int num);
+int nfsd_stat_init(void);
+void nfsd_stat_shutdown(void);
+
+static inline void nfsd_stats_rc_hits_inc(void)
+{
+	percpu_counter_inc(&nfsdstats.counter[NFSD_STATS_RC_HITS]);
+}
+
+static inline void nfsd_stats_rc_misses_inc(void)
+{
+	percpu_counter_inc(&nfsdstats.counter[NFSD_STATS_RC_MISSES]);
+}
+
+static inline void nfsd_stats_rc_nocache_inc(void)
+{
+	percpu_counter_inc(&nfsdstats.counter[NFSD_STATS_RC_NOCACHE]);
+}
+
+static inline void nfsd_stats_fh_stale_inc(void)
+{
+	percpu_counter_inc(&nfsdstats.counter[NFSD_STATS_FH_STALE]);
+}
+
+static inline void nfsd_stats_io_read_add(s64 amount)
+{
+	percpu_counter_add(&nfsdstats.counter[NFSD_STATS_IO_READ], amount);
+}
+
+static inline void nfsd_stats_io_write_add(s64 amount)
+{
+	percpu_counter_add(&nfsdstats.counter[NFSD_STATS_IO_WRITE], amount);
+}
+
+static inline void nfsd_stats_payload_misses_inc(struct nfsd_net *nn)
+{
+	percpu_counter_inc(&nn->counter[NFSD_NET_PAYLOAD_MISSES]);
+}
+
+static inline void nfsd_stats_drc_mem_usage_add(struct nfsd_net *nn, s64 amount)
+{
+	percpu_counter_add(&nn->counter[NFSD_NET_DRC_MEM_USAGE], amount);
+}
+
+static inline void nfsd_stats_drc_mem_usage_sub(struct nfsd_net *nn, s64 amount)
+{
+	percpu_counter_sub(&nn->counter[NFSD_NET_DRC_MEM_USAGE], amount);
+}
 
 #endif /* _NFSD_STATS_H */