When wbc.more_io was first introduced, it indicates whether there are
at least one superblock whose s_more_io contains more IO work. Now with
the per-bdi writeback, it can be replaced with a simple b_more_io test.

Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Mel Gorman <redacted>
CC: Minchan Kim <redacted>
Signed-off-by: Wu Fengguang <redacted>
---
 fs/fs-writeback.c                |    9 ++-------
 include/linux/writeback.h        |    1 -
 include/trace/events/ext4.h      |    6 ++----
 include/trace/events/writeback.h |    5 +----
 4 files changed, 5 insertions(+), 16 deletions(-)

--- linux-next.orig/fs/fs-writeback.c	2011-05-05 23:30:30.000000000 +0800
+++ linux-next/fs/fs-writeback.c	2011-05-05 23:30:33.000000000 +0800

@@ -560,12 +560,8 @@ static int writeback_sb_inodes(struct su
 		iput(inode);
 		cond_resched();
 		spin_lock(&wb->list_lock);
-		if (wbc->nr_to_write <= 0) {
-			wbc->more_io = 1;
+		if (wbc->nr_to_write <= 0)
 			return 1;
-		}
-		if (!list_empty(&wb->b_more_io))
-			wbc->more_io = 1;
 	}
 	/* b_io is empty */
 	return 1;

@@ -707,7 +703,6 @@ static long wb_writeback(struct bdi_writ
 			wbc.older_than_this = &oldest_jif;
 		}
 
-		wbc.more_io = 0;
 		wbc.nr_to_write = write_chunk;
 		wbc.pages_skipped = 0;
 		wbc.inodes_cleaned = 0;

@@ -755,7 +750,7 @@ retry:
 		/*
 		 * No more inodes for IO, bail
 		 */
-		if (!wbc.more_io)
+		if (list_empty(&wb->b_more_io))
 			break;