writeback: move backing_dev_info->state into bdi_writeback

Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear.  For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi.  To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.

This patch moves bdi->state into wb.

* enum bdi_state is renamed to wb_state and the prefix of all enums is
  changed from BDI_ to WB_.

* Explicit zeroing of bdi->state is removed without adding zeoring of
  wb->state as the whole data structure is zeroed on init anyway.

* As there's still only one bdi_writeback per backing_dev_info, all
  uses of bdi->state are mechanically replaced with bdi->wb.state
  introducing no behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: drbd-dev@lists.linbit.com
Cc: Neil Brown <neilb@suse.de>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 7 insertions, 7 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 32a8bbd7a9ad..983312cea245 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -74,7 +74,7 @@ unsigned int dirtytime_expire_interval = 12 * 60 * 60;
  */
 int writeback_in_progress(struct backing_dev_info *bdi)
 {
-	return test_bit(BDI_writeback_running, &bdi->state);
+	return test_bit(WB_writeback_running, &bdi->wb.state);
 }
 EXPORT_SYMBOL(writeback_in_progress);
 
@@ -112,7 +112,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage);
 static void bdi_wakeup_thread(struct backing_dev_info *bdi)
 {
 	spin_lock_bh(&bdi->wb_lock);
-	if (test_bit(BDI_registered, &bdi->state))
+	if (test_bit(WB_registered, &bdi->wb.state))
 		mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
 	spin_unlock_bh(&bdi->wb_lock);
 }
@@ -123,7 +123,7 @@ static void bdi_queue_work(struct backing_dev_info *bdi,
 	trace_writeback_queue(bdi, work);
 
 	spin_lock_bh(&bdi->wb_lock);
-	if (!test_bit(BDI_registered, &bdi->state)) {
+	if (!test_bit(WB_registered, &bdi->wb.state)) {
 		if (work->done)
 			complete(work->done);
 		goto out_unlock;
@@ -1057,7 +1057,7 @@ static long wb_do_writeback(struct bdi_writeback *wb)
 	struct wb_writeback_work *work;
 	long wrote = 0;
 
-	set_bit(BDI_writeback_running, &wb->bdi->state);
+	set_bit(WB_writeback_running, &wb->state);
 	while ((work = get_next_work_item(bdi)) != NULL) {
 
 		trace_writeback_exec(bdi, work);
@@ -1079,7 +1079,7 @@ static long wb_do_writeback(struct bdi_writeback *wb)
 	 */
 	wrote += wb_check_old_data_flush(wb);
 	wrote += wb_check_background_flush(wb);
-	clear_bit(BDI_writeback_running, &wb->bdi->state);
+	clear_bit(WB_writeback_running, &wb->state);
 
 	return wrote;
 }
@@ -1099,7 +1099,7 @@ void bdi_writeback_workfn(struct work_struct *work)
 	current->flags |= PF_SWAPWRITE;
 
 	if (likely(!current_is_workqueue_rescuer() ||
-		   !test_bit(BDI_registered, &bdi->state))) {
+		   !test_bit(WB_registered, &wb->state))) {
 		/*
 		 * The normal path.  Keep writing back @bdi until its
 		 * work_list is empty.  Note that this path is also taken
@@ -1323,7 +1323,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 			spin_unlock(&inode->i_lock);
 			spin_lock(&bdi->wb.list_lock);
 			if (bdi_cap_writeback_dirty(bdi)) {
-				WARN(!test_bit(BDI_registered, &bdi->state),
+				WARN(!test_bit(WB_registered, &bdi->wb.state),
 				     "bdi-%s not registered\n", bdi->name);
 
 				/*