[PATCH 2/9] writeback: account per-bdi accumulated written pages

[Wu Fengguang <fengguang.wu@intel.com>]

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From: Jan Kara <jack@suse.cz>

Introduce the BDI_WRITTEN counter. It will be used for estimating the
bdi's write bandwidth.

Peter Zijlstra <a.p.zijlstra@chello.nl>:
Move BDI_WRITTEN accounting into __bdi_writeout_inc().
This will cover and fix fuse, which only calls bdi_writeout_inc().

CC: Michael Rubin <mrubin@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 include/linux/backing-dev.h |    1 +
 mm/backing-dev.c            |   10 ++++++++--
 mm/page-writeback.c         |    1 +
 3 files changed, 10 insertions(+), 2 deletions(-)

--- linux-next.orig/include/linux/backing-dev.h	2011-06-12 13:29:02.000000000 +0800
+++ linux-next/include/linux/backing-dev.h	2011-06-12 20:48:47.000000000 +0800
@@ -40,6 +40,7 @@ typedef int (congested_fn)(void *, int);
 enum bdi_stat_item {
 	BDI_RECLAIMABLE,
 	BDI_WRITEBACK,
+	BDI_WRITTEN,
 	NR_BDI_STAT_ITEMS
 };
 
--- linux-next.orig/mm/backing-dev.c	2011-06-12 13:29:02.000000000 +0800
+++ linux-next/mm/backing-dev.c	2011-06-12 20:49:51.000000000 +0800
@@ -97,6 +97,7 @@ static int bdi_debug_stats_show(struct s
 		   "BdiDirtyThresh:   %8lu kB\n"
 		   "DirtyThresh:      %8lu kB\n"
 		   "BackgroundThresh: %8lu kB\n"
+		   "BdiWritten:       %8lu kB\n"
 		   "b_dirty:          %8lu\n"
 		   "b_io:             %8lu\n"
 		   "b_more_io:        %8lu\n"
@@ -104,8 +105,13 @@ static int bdi_debug_stats_show(struct s
 		   "state:            %8lx\n",
 		   (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
 		   (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
-		   K(bdi_thresh), K(dirty_thresh),
-		   K(background_thresh), nr_dirty, nr_io, nr_more_io,
+		   K(bdi_thresh),
+		   K(dirty_thresh),
+		   K(background_thresh),
+		   (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
+		   nr_dirty,
+		   nr_io,
+		   nr_more_io,
 		   !list_empty(&bdi->bdi_list), bdi->state);
 #undef K
 
--- linux-next.orig/mm/page-writeback.c	2011-06-12 13:29:06.000000000 +0800
+++ linux-next/mm/page-writeback.c	2011-06-12 20:48:47.000000000 +0800
@@ -219,6 +219,7 @@ int dirty_bytes_handler(struct ctl_table
  */
 static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
 {
+	__inc_bdi_stat(bdi, BDI_WRITTEN);
 	__prop_inc_percpu_max(&vm_completions, &bdi->completions,
 			      bdi->max_prop_frac);
 }