mm: write_cache_pages more terminate quickly

Now that we have the early-termination logic in place, it makes sense to
bail out early in all other cases where done is set to 1.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page-writeback.c

@@ -983,12 +983,15 @@ continue_unlock:
 
 			if (wbc->sync_mode == WB_SYNC_NONE) {
 				wbc->nr_to_write--;
-				if (wbc->nr_to_write <= 0)
+				if (wbc->nr_to_write <= 0) {
 					done = 1;
+					break;
+				}
 			}
 			if (wbc->nonblocking && bdi_write_congested(bdi)) {
 				wbc->encountered_congestion = 1;
 				done = 1;
+				break;
 			}
 		}
 		pagevec_release(&pvec);