linux-kernel - Re: [PATCH 4/5] writeback: remove pages_skipped accounting in __block_write_full

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Date:	Wed, 3 Oct 2007 07:55:18 +1000
From:	David Chinner <dgc@....com>
To:	Fengguang Wu <wfg@...l.ustc.edu.cn>
Cc:	Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
	David Chinner <dgc@....com>, Ken Chen <kenchen@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michael Rubin <mrubin@...gle.com>
Subject: Re: [PATCH 4/5] writeback: remove pages_skipped accounting in __block_write_full_page()

> 
> do not quite agree with each other. The page writeback should be skipped for
> 'locked buffer', but here it is 'clean buffer'!

Ok, so that means we need an equivalent fix in xfs_start_page_writeback()
as it will skip pages with clean buffers just like this. Something like
this (untested)?

---
 fs/xfs/linux-2.6/xfs_aops.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_aops.c	2007-10-02 16:12:56.000000000 +1000
+++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_aops.c	2007-10-03 07:53:27.866602431 +1000
@@ -420,10 +420,9 @@ xfs_start_page_writeback(
 		clear_page_dirty_for_io(page);
 	set_page_writeback(page);
 	unlock_page(page);
-	if (!buffers) {
+	/* If no buffers on the page are to be written, finish it here */
+	if (!buffers)
 		end_page_writeback(page);
-		wbc->pages_skipped++;	/* We didn't write this page */
-	}
 }
 
 static inline int bio_add_buffer(struct bio *bio, struct buffer_head *bh)

-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group

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