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>

3 files changed, 4 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
 };
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index a87da524a4a0..fea7e6efd1d7 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -97,6 +97,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                    "BdiDirtyThresh:     %10lu kB\n"
                    "DirtyThresh:        %10lu kB\n"
                    "BackgroundThresh:   %10lu kB\n"
+                   "BdiDirtied:         %10lu kB\n"
                    "BdiWritten:         %10lu kB\n"
                    "BdiWriteBandwidth:  %10lu kBps\n"
                    "b_dirty:            %10lu\n"
@@ -109,6 +110,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                    K(bdi_thresh),
                    K(dirty_thresh),
                    K(background_thresh),
+                   (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)),
                    (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
                    (unsigned long) K(bdi->write_bandwidth),
                    nr_dirty,
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0e309cd1b5b9..0e6dd5c2ed31 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1322,6 +1322,7 @@ void account_page_dirtied(struct page *page, struct address_space *mapping)
                 __inc_zone_page_state(page, NR_FILE_DIRTY);
                 __inc_zone_page_state(page, NR_DIRTIED);
                 __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
+                __inc_bdi_stat(mapping->backing_dev_info, BDI_DIRTIED);
                 task_dirty_inc(current);
                 task_io_account_write(PAGE_CACHE_SIZE);
         }