Count per BDI writeback pages. Signed-off-by: Peter Zijlstra --- include/linux/backing-dev.h | 1 + mm/page-writeback.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 2 deletions(-) Index: linux-2.6/mm/page-writeback.c =================================================================== --- linux-2.6.orig/mm/page-writeback.c +++ linux-2.6/mm/page-writeback.c @@ -981,14 +981,18 @@ int test_clear_page_writeback(struct pag int ret; if (mapping) { + struct backing_dev_info *bdi = mapping->backing_dev_info; unsigned long flags; write_lock_irqsave(&mapping->tree_lock, flags); ret = TestClearPageWriteback(page); - if (ret) + if (ret) { radix_tree_tag_clear(&mapping->page_tree, page_index(page), PAGECACHE_TAG_WRITEBACK); + if (bdi_cap_writeback_dirty(bdi)) + __dec_bdi_stat(bdi, BDI_WRITEBACK); + } write_unlock_irqrestore(&mapping->tree_lock, flags); } else { ret = TestClearPageWriteback(page); @@ -1004,14 +1008,18 @@ int test_set_page_writeback(struct page int ret; if (mapping) { + struct backing_dev_info *bdi = mapping->backing_dev_info; unsigned long flags; write_lock_irqsave(&mapping->tree_lock, flags); ret = TestSetPageWriteback(page); - if (!ret) + if (!ret) { radix_tree_tag_set(&mapping->page_tree, page_index(page), PAGECACHE_TAG_WRITEBACK); + if (bdi_cap_writeback_dirty(bdi)) + __inc_bdi_stat(bdi, BDI_WRITEBACK); + } if (!PageDirty(page)) radix_tree_tag_clear(&mapping->page_tree, page_index(page), Index: linux-2.6/include/linux/backing-dev.h =================================================================== --- linux-2.6.orig/include/linux/backing-dev.h +++ linux-2.6/include/linux/backing-dev.h @@ -28,6 +28,7 @@ typedef int (congested_fn)(void *, int); enum bdi_stat_item { BDI_RECLAIMABLE, + BDI_WRITEBACK, NR_BDI_STAT_ITEMS }; --