writeback: rename domain_update_bandwidth()

Rename domain_update_bandwidth() to domain_update_dirty_limit().  The
original name is a misnomer.  The function has nothing to do with a
bandwidth, it updates dirty limits.

Link: https://lkml.kernel.org/r/20210713104716.22868-4-jack@suse.czSigned-off-by: Jan Kara <jack@suse.cz>
Cc: Michael Stapelberg <stapelberg+linux@google.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page-writeback.c

@@ -1147,7 +1147,7 @@ static void update_dirty_limit(struct dirty_throttle_control *dtc)
 	dom->dirty_limit = limit;
 }
 
-static void domain_update_bandwidth(struct dirty_throttle_control *dtc,
+static void domain_update_dirty_limit(struct dirty_throttle_control *dtc,
 				      unsigned long now)
 {
 	struct wb_domain *dom = dtc_dom(dtc);
@@ -1353,7 +1353,7 @@ static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc,
 	written = percpu_counter_read(&wb->stat[WB_WRITTEN]);
 
 	if (update_ratelimit) {
-		domain_update_bandwidth(gdtc, now);
+		domain_update_dirty_limit(gdtc, now);
 		wb_update_dirty_ratelimit(gdtc, dirtied, elapsed);
 
 		/*
@@ -1361,7 +1361,7 @@ static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc,
 		 * compiler has no way to figure that out.  Help it.
 		 */
 		if (IS_ENABLED(CONFIG_CGROUP_WRITEBACK) && mdtc) {
-			domain_update_bandwidth(mdtc, now);
+			domain_update_dirty_limit(mdtc, now);
 			wb_update_dirty_ratelimit(mdtc, dirtied, elapsed);
 		}
 	}