percpu counter: clean up percpu_counter_sum_and_set() interface

From: Mingming Cao

percpu_counter_sum_and_set() and percpu_counter_sum() is the same except
the former update the global counter after accounting. Since we are
taking the fbc->lock to calculate the precise value of the
counter in percpu_counter_sum() anyway, it should simply set fbc->count
too, as the percpu_counter_sum_and_set() dose.

This patch merge these two interfaces into one.

Signed-off-by: Mingming Cao
---
fs/ext4/balloc.c | 2 +-
include/linux/percpu_counter.h | 12 +++---------
lib/percpu_counter.c | 8 +++-----
3 files changed, 7 insertions(+), 15 deletions(-)

Index: linux-2.6.27-rc3/fs/ext4/balloc.c
================================================== =================
--- linux-2.6.27-rc3.orig/fs/ext4/balloc.c 2008-08-20 16:23:26.000000000 -0700
+++ linux-2.6.27-rc3/fs/ext4/balloc.c 2008-08-20 16:25:21.000000000 -0700
@@ -1624,7 +1624,7 @@
#ifdef CONFIG_SMP
if (free_blocks - root_blocks < FBC_BATCH)
free_blocks =
- percpu_counter_sum_and_set(&sbi->s_freeblocks_counter);
+ percpu_counter_sum(&sbi->s_freeblocks_counter);
#endif
if (free_blocks <= root_blocks)
/* we don't have free space */
Index: linux-2.6.27-rc3/include/linux/percpu_counter.h
================================================== =================
--- linux-2.6.27-rc3.orig/include/linux/percpu_counter.h 2008-08-20 16:23:51.000000000 -0700
+++ linux-2.6.27-rc3/include/linux/percpu_counter.h 2008-08-20 16:29:17.000000000 -0700
@@ -35,7 +35,7 @@
void percpu_counter_destroy(struct percpu_counter *fbc);
void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
-s64 __percpu_counter_sum(struct percpu_counter *fbc, int set);
+s64 __percpu_counter_sum(struct percpu_counter *fbc);

static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
@@ -44,19 +44,13 @@

static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
{
- s64 ret = __percpu_counter_sum(fbc, 0);
+ s64 ret = __percpu_counter_sum(fbc);
return ret < 0 ? 0 : ret;
}

-static inline s64 percpu_counter_sum_and_set(struct percpu_counter *fbc)
-{
- return __percpu_counter_sum(fbc, 1);
-}
-
-
static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
{
- return __percpu_counter_sum(fbc, 0);
+ return __percpu_counter_sum(fbc);
}

static inline s64 percpu_counter_read(struct percpu_counter *fbc)
Index: linux-2.6.27-rc3/lib/percpu_counter.c
================================================== =================
--- linux-2.6.27-rc3.orig/lib/percpu_counter.c 2008-08-20 16:24:50.000000000 -0700
+++ linux-2.6.27-rc3/lib/percpu_counter.c 2008-08-20 16:26:55.000000000 -0700
@@ -52,7 +52,7 @@
* Add up all the per-cpu counts, return the result. This is a more accurate
* but much slower version of percpu_counter_read_positive()
*/
-s64 __percpu_counter_sum(struct percpu_counter *fbc, int set)
+s64 __percpu_counter_sum(struct percpu_counter *fbc)
{
s64 ret;
int cpu;
@@ -62,11 +62,9 @@
for_each_online_cpu(cpu) {
s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
ret += *pcount;
- if (set)
- *pcount = 0;
+ *pcount = 0;
}
- if (set)
- fbc->count = ret;
+ fbc->count = ret;

spin_unlock(&fbc->lock);
return ret;


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