Revert "writeback: fix WB_SYNC_NONE writeback from umount"

This reverts commit e913fc825dc685a444cb4c1d0f9d32f372f59861.

We are investigating a hang associated with the WB_SYNC_NONE changes,
so revert them for now.

Conflicts:

	fs/fs-writeback.c
	mm/page-writeback.c

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/fs/sync.c b/fs/sync.c
index e8cbd41..5a537cc 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -42,7 +42,7 @@
 	if (wait)
 		sync_inodes_sb(sb);
 	else
-		writeback_inodes_sb_locked(sb);
+		writeback_inodes_sb(sb);
 
 	if (sb->s_op->sync_fs)
 		sb->s_op->sync_fs(sb, wait);