linux-kernel - [PATCH 07/45] writeback: attribute stats to the matching per-cgroup bdi

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Date:	Tue,  6 Jan 2015 16:25:44 -0500
From:	Tejun Heo <tj@...nel.org>
To:	axboe@...nel.dk
Cc:	linux-kernel@...r.kernel.org, jack@...e.cz, hch@...radead.org,
	hannes@...xchg.org, linux-fsdevel@...r.kernel.org,
	vgoyal@...hat.com, lizefan@...wei.com, cgroups@...r.kernel.org,
	linux-mm@...ck.org, mhocko@...e.cz, clm@...com,
	fengguang.wu@...el.com, david@...morbit.com,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 07/45] writeback: attribute stats to the matching per-cgroup bdi_writeback

Until now, all WB_* stats were accounted against the root wb
(bdi_writeback), now that multiple wb (bdi_writeback) support is in
place, let's attributes the stats to the respective per-cgroup wb's.

WB_RECLAIMABLE and WB_DIRTIED are attributed to the page's dirty cgwb
(per-cgroup wb) and WB_WRITEBACK to writeback cgwb.
__test_set_page_writeback() is updated so that dirty cgwb association
takes place before WB_WRITEBACK increment so that the latter can make
use of the association.

As no filesystem has FS_CGROUP_WRITEBACK yet, this doesn't lead to
visible behavior differences.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Jan Kara <jack@...e.cz>
---
 mm/filemap.c        |  2 +-
 mm/page-writeback.c | 18 ++++++++++++------
 mm/truncate.c       |  3 +--
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 98a6675..faa577d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -211,7 +211,7 @@ void __delete_from_page_cache(struct page *page, void *shadow)
 	 */
 	if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
 		dec_zone_page_state(page, NR_FILE_DIRTY);
-		dec_wb_stat(&mapping->backing_dev_info->wb, WB_RECLAIMABLE);
+		dec_wb_stat(page_cgwb_dirty(page), WB_RECLAIMABLE);
 		page_blkcg_detach_dirty(page);
 	}
 }
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 6475504..d1fea3a 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2159,10 +2159,13 @@ EXPORT_SYMBOL(__set_page_dirty_nobuffers);
 void account_page_redirty(struct page *page)
 {
 	struct address_space *mapping = page->mapping;
+
 	if (mapping && mapping_cap_account_dirty(mapping)) {
+		struct bdi_writeback *wb = page_cgwb_dirty(page);
+
 		current->nr_dirtied--;
 		dec_zone_page_state(page, NR_DIRTIED);
-		dec_wb_stat(&mapping->backing_dev_info->wb, WB_DIRTIED);
+		dec_wb_stat(wb, WB_DIRTIED);
 	}
 }
 EXPORT_SYMBOL(account_page_redirty);
@@ -2300,9 +2303,10 @@ int clear_page_dirty_for_io(struct page *page)
 		 * exclusion.
 		 */
 		if (TestClearPageDirty(page)) {
+			struct bdi_writeback *wb = page_cgwb_dirty(page);
+
 			dec_zone_page_state(page, NR_FILE_DIRTY);
-			dec_wb_stat(&mapping->backing_dev_info->wb,
-				    WB_RECLAIMABLE);
+			dec_wb_stat(wb, WB_RECLAIMABLE);
 			page_blkcg_detach_dirty(page);
 			return 1;
 		}
@@ -2330,9 +2334,11 @@ int test_clear_page_writeback(struct page *page)
 						page_index(page),
 						PAGECACHE_TAG_WRITEBACK);
 			if (bdi_cap_account_writeback(bdi)) {
-				__dec_wb_stat(&bdi->wb, WB_WRITEBACK);
+				struct bdi_writeback *wb = page_cgwb_wb(page);
+
+				__dec_wb_stat(wb, WB_WRITEBACK);
 				page_blkcg_detach_wb(page);
-				__wb_writeout_inc(&bdi->wb);
+				__wb_writeout_inc(wb);
 			}
 		}
 		spin_unlock_irqrestore(&mapping->tree_lock, flags);
@@ -2366,8 +2372,8 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
 						page_index(page),
 						PAGECACHE_TAG_WRITEBACK);
 			if (bdi_cap_account_writeback(bdi)) {
-				__inc_wb_stat(&bdi->wb, WB_WRITEBACK);
 				page_blkcg_attach_wb(page);
+				__inc_wb_stat(page_cgwb_wb(page), WB_WRITEBACK);
 			}
 		}
 		if (!PageDirty(page))
diff --git a/mm/truncate.c b/mm/truncate.c
index caae624..1658e34 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -112,8 +112,7 @@ 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_wb_stat(&mapping->backing_dev_info->wb,
-				    WB_RECLAIMABLE);
+			dec_wb_stat(page_cgwb_dirty(page), WB_RECLAIMABLE);
 			if (account_size)
 				task_io_account_cancelled_write(account_size);
 			page_blkcg_detach_dirty(page);
-- 
2.1.0

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