[this_cpu_xx V2 04/19] Use this_cpu operations for NFS statistics

[cl@linux-foundation.org]

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Simplify NFS statistics and allow the use of optimized
arch instructions.

CC: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>

---
 fs/nfs/iostat.h |   30 +++++++++---------------------
 1 file changed, 9 insertions(+), 21 deletions(-)

Index: linux-2.6/fs/nfs/iostat.h
===================================================================
--- linux-2.6.orig/fs/nfs/iostat.h	2009-06-17 09:10:00.000000000 -0500
+++ linux-2.6/fs/nfs/iostat.h	2009-06-17 09:21:02.000000000 -0500
@@ -25,13 +25,7 @@ struct nfs_iostats {
 static inline void nfs_inc_server_stats(const struct nfs_server *server,
 					enum nfs_stat_eventcounters stat)
 {
-	struct nfs_iostats *iostats;
-	int cpu;
-
-	cpu = get_cpu();
-	iostats = per_cpu_ptr(server->io_stats, cpu);
-	iostats->events[stat]++;
-	put_cpu();
+	this_cpu_inc(server->io_stats->events[stat]);
 }
 
 static inline void nfs_inc_stats(const struct inode *inode,
@@ -44,13 +38,13 @@ static inline void nfs_add_server_stats(
 					enum nfs_stat_bytecounters stat,
 					unsigned long addend)
 {
-	struct nfs_iostats *iostats;
-	int cpu;
-
-	cpu = get_cpu();
-	iostats = per_cpu_ptr(server->io_stats, cpu);
-	iostats->bytes[stat] += addend;
-	put_cpu();
+	/*
+	 * bytes is larger than word size on 32 bit platforms.
+	 * Thus we cannot use this_cpu_add() here.
+	 */
+	preempt_disable();
+	*this_cpu_ptr(&server->io_stats->bytes[stat]) +=  addend;
+	preempt_enable_no_resched();
 }
 
 static inline void nfs_add_stats(const struct inode *inode,
@@ -65,13 +59,7 @@ static inline void nfs_add_fscache_stats
 					 enum nfs_stat_fscachecounters stat,
 					 unsigned long addend)
 {
-	struct nfs_iostats *iostats;
-	int cpu;
-
-	cpu = get_cpu();
-	iostats = per_cpu_ptr(NFS_SERVER(inode)->io_stats, cpu);
-	iostats->fscache[stat] += addend;
-	put_cpu();
+	this_cpu_add(NFS_SERVER(inode)->io_stats->fscache[stat], addend);
 }
 #endif
 

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