buffer, writeback: make __block_write_full_page() honor cgroup writeback

[__]block_write_full_page() is used to implement ->writepage in
various filesystems.  All writeback logic is now updated to handle
cgroup writeback and the block cgroup to issue IOs for is encoded in
writeback_control and can be retrieved from the inode; however,
[__]block_write_full_page() currently ignores the blkcg indicated by
inode and issues all bio's without explicit blkcg association.

This patch adds submit_bh_blkcg() which associates the bio with the
specified blkio cgroup before issuing and uses it in
__block_write_full_page() so that the issued bio's are associated with
inode_to_wb_blkcg_css(inode).

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>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 9cc11e5b97ca..e9d7373f5f93 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -393,6 +393,12 @@ static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
 	return inode->i_wb;
 }
 
+static inline struct cgroup_subsys_state *
+inode_to_wb_blkcg_css(struct inode *inode)
+{
+	return inode_to_wb(inode)->blkcg_css;
+}
+
 struct wb_iter {
 	int			start_blkcg_id;
 	struct radix_tree_iter	tree_iter;
@@ -510,6 +516,12 @@ static inline void wb_blkcg_offline(struct blkcg *blkcg)
 {
 }
 
+static inline struct cgroup_subsys_state *
+inode_to_wb_blkcg_css(struct inode *inode)
+{
+	return blkcg_root_css;
+}
+
 struct wb_iter {
 	int		next_id;
 };