writeback: account per-bdi accumulated dirtied pages

Introduce the BDI_DIRTIED counter. It will be used for estimating the
bdi's dirty bandwidth.

CC: Jan Kara <jack@suse.cz>
CC: Michael Rubin <mrubin@google.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 3b2f9cb82986..9ca241a70c49 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -40,6 +40,7 @@ typedef int (congested_fn)(void *, int);
 enum bdi_stat_item {
         BDI_RECLAIMABLE,
         BDI_WRITEBACK,
+        BDI_DIRTIED,
         BDI_WRITTEN,
         NR_BDI_STAT_ITEMS
 };