Most architectures have fast path to access percpu for current cpu.
Required preempt_disable() is provided by part_stat_lock().

Signed-off-by: Konstantin Khlebnikov <khlebni...@yandex-team.ru>
---
 include/linux/part_stat.h |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/linux/part_stat.h b/include/linux/part_stat.h
index 755a01f0fd61..a0ddeff3798e 100644
--- a/include/linux/part_stat.h
+++ b/include/linux/part_stat.h
@@ -36,6 +36,9 @@
        res;                                                            \
 })
 
+#define __part_stat_add(part, field, addnd)                            \
+       __this_cpu_add((part)->dkstats->field, addnd)
+
 static inline void part_stat_set_all(struct hd_struct *part, int value)
 {
        int i;
@@ -64,6 +67,9 @@ static inline void free_part_stats(struct hd_struct *part)
 #define part_stat_get_cpu(part, field, cpu)    part_stat_get(part, field)
 #define part_stat_read(part, field)            part_stat_get(part, field)
 
+#define __part_stat_add(part, field, addnd)                            \
+       (part_stat_get(part, field) += (addnd))
+
 static inline void part_stat_set_all(struct hd_struct *part, int value)
 {
        memset(&part->dkstats, value, sizeof(struct disk_stats));
@@ -85,9 +91,6 @@ static inline void free_part_stats(struct hd_struct *part)
         part_stat_read(part, field[STAT_WRITE]) +                      \
         part_stat_read(part, field[STAT_DISCARD]))
 
-#define __part_stat_add(part, field, addnd)                            \
-       (part_stat_get(part, field) += (addnd))
-
 #define part_stat_add(part, field, addnd)      do {                    \
        __part_stat_add((part), field, addnd);                          \
        if ((part)->partno)                                             \

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