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, 4 insertions, 0 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index d821321326e3..9b3c4ee62abf 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -827,6 +827,8 @@ int __set_page_dirty_nobuffers(struct page *page)
                         WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
                         if (mapping_cap_account_dirty(mapping)) {
                                 __inc_zone_page_state(page, NR_FILE_DIRTY);
+                                __inc_bdi_stat(mapping->backing_dev_info,
+                                                BDI_RECLAIMABLE);
                                 task_io_account_write(PAGE_CACHE_SIZE);
                         }
                         radix_tree_tag_set(&mapping->page_tree,
@@ -961,6 +963,8 @@ int clear_page_dirty_for_io(struct page *page)
                  */
                 if (TestClearPageDirty(page)) {
                         dec_zone_page_state(page, NR_FILE_DIRTY);
+                        dec_bdi_stat(mapping->backing_dev_info,
+                                        BDI_RECLAIMABLE);
                         return 1;
                 }
                 return 0;