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.

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

v2: Updated for per-inode wb association.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 9b95cf80b4075386af2d35b81aa7300333a69a2a..4d0a9da2de6b1bc4d3b28d32e4cfe652c9dd2aee 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2130,7 +2130,7 @@ void account_page_cleaned(struct page *page, struct address_space *mapping,
        if (mapping_cap_account_dirty(mapping)) {
                mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
                dec_zone_page_state(page, NR_FILE_DIRTY);
-               dec_wb_stat(&inode_to_bdi(mapping->host)->wb, WB_RECLAIMABLE);
+               dec_wb_stat(inode_to_wb(mapping->host), WB_RECLAIMABLE);
                task_io_account_cancelled_write(PAGE_CACHE_SIZE);
        }
 }
@@ -2191,10 +2191,13 @@ 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 = inode_to_wb(mapping->host);
+
                current->nr_dirtied--;
                dec_zone_page_state(page, NR_DIRTIED);
-               dec_wb_stat(&inode_to_bdi(mapping->host)->wb, WB_DIRTIED);
+               dec_wb_stat(wb, WB_DIRTIED);
        }
 }
 EXPORT_SYMBOL(account_page_redirty);
@@ -2373,8 +2376,7 @@ int clear_page_dirty_for_io(struct page *page)
                if (TestClearPageDirty(page)) {
                        mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
                        dec_zone_page_state(page, NR_FILE_DIRTY);
-                       dec_wb_stat(&inode_to_bdi(mapping->host)->wb,
-                                   WB_RECLAIMABLE);
+                       dec_wb_stat(inode_to_wb(mapping->host), WB_RECLAIMABLE);
                        ret = 1;
                }
                mem_cgroup_end_page_stat(memcg);
@@ -2392,7 +2394,8 @@ int test_clear_page_writeback(struct page *page)
 
        memcg = mem_cgroup_begin_page_stat(page);
        if (mapping) {
-               struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
+               struct inode *inode = mapping->host;
+               struct backing_dev_info *bdi = inode_to_bdi(inode);
                unsigned long flags;
 
                spin_lock_irqsave(&mapping->tree_lock, flags);
@@ -2402,8 +2405,10 @@ 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);
-                               __wb_writeout_inc(&bdi->wb);
+                               struct bdi_writeback *wb = inode_to_wb(inode);
+
+                               __dec_wb_stat(wb, WB_WRITEBACK);
+                               __wb_writeout_inc(wb);
                        }
                }
                spin_unlock_irqrestore(&mapping->tree_lock, flags);
@@ -2427,7 +2432,8 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
 
        memcg = mem_cgroup_begin_page_stat(page);
        if (mapping) {
-               struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
+               struct inode *inode = mapping->host;
+               struct backing_dev_info *bdi = inode_to_bdi(inode);
                unsigned long flags;
 
                spin_lock_irqsave(&mapping->tree_lock, flags);
@@ -2437,7 +2443,7 @@ 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);
+                               __inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK);
                }
                if (!PageDirty(page))
                        radix_tree_tag_clear(&mapping->page_tree,