linux-ext4 - Re: regression: 100% io-wait with 2.6.24-rcX

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Date:	Mon, 14 Jan 2008 17:55:18 +0800
From:	Fengguang Wu <wfg@...l.ustc.edu.cn>
To:	Joerg Platte <jplatte@...sa.net>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: Re: regression: 100% io-wait with 2.6.24-rcX

On Mon, Jan 14, 2008 at 11:54:39AM +0800, Fengguang Wu wrote:
> > particular this bug is triggered because the dir mapping page has
> > PAGECACHE_TAG_DIRTY set and PG_dirty cleared, staying in an
> > inconsistent state.
> 
> Just found that a deleted dir will enter that inconsistent state when
> someone still have reference to it...

Joerg, this patch fixed the bug for me :-)

Fengguang
---

clear PAGECACHE_TAG_DIRTY for truncated page in block_write_full_page()

The `truncated' page in block_write_full_page() may stick for a long time.
E.g. ext2_rmdir() will set i_size to 0. The dir may still be referenced by
someone, and have dirty pages in it.

So clear PAGECACHE_TAG_DIRTY to prevent pdflush from retrying and iowaiting on
it.

Signed-off-by: Fengguang Wu <wfg@...l.ustc.edu.cn>
---
fs/buffer.c |    2 ++
 1 files changed, 2 insertions(+)

Index: linux/fs/buffer.c
===================================================================
--- linux.orig/fs/buffer.c
+++ linux/fs/buffer.c
@@ -2820,7 +2820,9 @@ int block_write_full_page(struct page *p
 		 * freeable here, so the page does not leak.
 		 */
 		do_invalidatepage(page, 0);
+		set_page_writeback(page);
 		unlock_page(page);
+		end_page_writeback(page);
 		return 0; /* don't care */
 	}
 

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