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Subject[03/24] percpu counter: clean up percpu_counter_sum_and_set()
2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Mingming Cao <cmm@us.ibm.com>

commit 1f7c14c62ce63805f9574664a6c6de3633d4a354 upstream.

percpu_counter_sum_and_set() and percpu_counter_sum() is the same except
the former updates 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() does.

This patch merges these two interfaces into one.

Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jayson R. King <dev@jaysonking.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

---
fs/ext4/balloc.c | 2 +-
include/linux/percpu_counter.h | 12 +++---------
lib/percpu_counter.c | 8 +++-----
3 files changed, 7 insertions(+), 15 deletions(-)
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -1778,7 +1778,7 @@ ext4_fsblk_t ext4_has_free_blocks(struct
#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 */
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -35,7 +35,7 @@ int percpu_counter_init_irq(struct percp
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 void percpu_counter_add(st

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)
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -52,7 +52,7 @@ EXPORT_SYMBOL(__percpu_counter_add);
* 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 @@ s64 __percpu_counter_sum(struct percpu_c
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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