mm: scalable bdi statistics counters

Provide scalable per backing_dev_info statistics counters.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 841901a9559..a47065e084a 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -5,6 +5,33 @@
 #include <linux/sched.h>
 #include <linux/module.h>
 
+int bdi_init(struct backing_dev_info *bdi)
+{
+        int i, j;
+        int err;
+
+        for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
+                err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
+                if (err) {
+                        for (j = 0; j < i; j++)
+                                percpu_counter_destroy(&bdi->bdi_stat[i]);
+                        break;
+                }
+        }
+
+        return err;
+}
+EXPORT_SYMBOL(bdi_init);
+
+void bdi_destroy(struct backing_dev_info *bdi)
+{
+        int i;
+
+        for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
+                percpu_counter_destroy(&bdi->bdi_stat[i]);
+}
+EXPORT_SYMBOL(bdi_destroy);
+
 static wait_queue_head_t congestion_wqh[2] = {
                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])