mm: count reclaimable pages per BDI

Count per BDI reclaimable pages; nr_reclaimable = nr_dirty + nr_unstable.

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, 2 insertions, 0 deletions

diff --git a/mm/truncate.c b/mm/truncate.c
index 5cdfbc1a59fd..ff78505453d4 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -72,6 +72,8 @@ void cancel_dirty_page(struct page *page, unsigned int account_size)
                 struct address_space *mapping = page->mapping;
                 if (mapping && mapping_cap_account_dirty(mapping)) {
                         dec_zone_page_state(page, NR_FILE_DIRTY);
+                        dec_bdi_stat(mapping->backing_dev_info,
+                                        BDI_RECLAIMABLE);
                         if (account_size)
                                 task_io_account_cancelled_write(account_size);
                 }