bdi: remove enum wb_congested_state

enum wb_congested_state and the member 'congested' in bdi_writeback are
useless since commit a88f209 ("remove congestion tracking
framework"), so remove it.

Link: https://lkml.kernel.org/r/20220719083349.87547-1-xiujianfeng@huawei.com
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/backing-dev-defs.h

@@ -28,11 +28,6 @@ enum wb_state {
 	WB_start_all,		/* nr_pages == 0 (all) work pending */
 };
 
-enum wb_congested_state {
-	WB_async_congested,	/* The async (write) queue is getting full */
-	WB_sync_congested,	/* The sync queue is getting full */
-};
-
 enum wb_stat_item {
 	WB_RECLAIMABLE,
 	WB_WRITEBACK,
@@ -122,8 +117,6 @@ struct bdi_writeback {
 	atomic_t writeback_inodes;	/* number of inodes under writeback */
 	struct percpu_counter stat[NR_WB_STAT_ITEMS];
 
-	unsigned long congested;	/* WB_[a]sync_congested flags */
-
 	unsigned long bw_time_stamp;	/* last time write bw is updated */
 	unsigned long dirtied_stamp;
 	unsigned long written_stamp;	/* pages written at bw_time_stamp */