[PATCH 3/6] writeback: kill writeback_control.more_io

[Wu Fengguang]

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.

Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
 fs/fs-writeback.c                |    9 ++-------
 include/linux/writeback.h        |    1 -
 include/trace/events/writeback.h |    5 +----
 3 files changed, 3 insertions(+), 12 deletions(-)

--- linux-next.orig/fs/fs-writeback.c	2010-07-22 11:23:27.000000000 +0800
+++ linux-next/fs/fs-writeback.c	2010-07-22 12:56:42.000000000 +0800
@@ -507,12 +507,8 @@ static int writeback_sb_inodes(struct su
 		iput(inode);
 		cond_resched();
 		spin_lock(&inode_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;
@@ -622,7 +618,6 @@ static long wb_writeback(struct bdi_writ
 		if (work->for_background && !over_bground_thresh())
 			break;
 
-		wbc.more_io = 0;
 		wbc.nr_to_write = MAX_WRITEBACK_PAGES;
 		wbc.pages_skipped = 0;
 
@@ -644,7 +639,7 @@ static long wb_writeback(struct bdi_writ
 		/*
 		 * Didn't write everything and we don't have more IO, bail
 		 */
-		if (!wbc.more_io)
+		if (list_empty(&wb->b_more_io))
 			break;
 		/*
 		 * Did we write something? Try for more
--- linux-next.orig/include/linux/writeback.h	2010-07-22 11:23:27.000000000 +0800
+++ linux-next/include/linux/writeback.h	2010-07-22 11:24:46.000000000 +0800
@@ -49,7 +49,6 @@ struct writeback_control {
 	unsigned for_background:1;	/* A background writeback */
 	unsigned for_reclaim:1;		/* Invoked from the page allocator */
 	unsigned range_cyclic:1;	/* range_start is cyclic */
-	unsigned more_io:1;		/* more io to be dispatched */
 };
 
 /*
--- linux-next.orig/include/trace/events/writeback.h	2010-07-22 11:23:27.000000000 +0800
+++ linux-next/include/trace/events/writeback.h	2010-07-22 11:24:46.000000000 +0800
@@ -99,7 +99,6 @@ DECLARE_EVENT_CLASS(wbc_class,
 		__field(int, for_background)
 		__field(int, for_reclaim)
 		__field(int, range_cyclic)
-		__field(int, more_io)
 		__field(long, range_start)
 		__field(long, range_end)
 	),
@@ -113,13 +112,12 @@ DECLARE_EVENT_CLASS(wbc_class,
 		__entry->for_background	= wbc->for_background;
 		__entry->for_reclaim	= wbc->for_reclaim;
 		__entry->range_cyclic	= wbc->range_cyclic;
-		__entry->more_io	= wbc->more_io;
 		__entry->range_start	= (long)wbc->range_start;
 		__entry->range_end	= (long)wbc->range_end;
 	),
 
 	TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d "
-		"bgrd=%d reclm=%d cyclic=%d more=%d "
+		"bgrd=%d reclm=%d cyclic=%d "
 		"start=0x%lx end=0x%lx",
 		__entry->name,
 		__entry->nr_to_write,
@@ -129,7 +127,6 @@ DECLARE_EVENT_CLASS(wbc_class,
 		__entry->for_background,
 		__entry->for_reclaim,
 		__entry->range_cyclic,
-		__entry->more_io,
 		__entry->range_start,
 		__entry->range_end)
 )


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