percpu counter: clean up percpu_counter_sum_and_set() From: Mingming Cao 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 merge these two interfaces into one. Signed-off-by: Mingming Cao Cc: Peter Zijlstra Cc: Signed-off-by: Andrew Morton Signed-off-by: "Theodore Ts'o" --- 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 17:25:35.000000000 -0700 +++ linux-2.6.27-rc3/fs/ext4/balloc.c 2008-08-21 14:34:32.000000000 -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 17:25:35.000000000 -0700 +++ linux-2.6.27-rc3/include/linux/percpu_counter.h 2008-08-21 14:34:32.000000000 -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 17:25:35.000000000 -0700 +++ linux-2.6.27-rc3/lib/percpu_counter.c 2008-08-21 14:34:32.000000000 -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;