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Date: Wed, 31 Dec 2003 03:17:36 -0800
From: Andrew Morton <akpm@osdl.org>
To: suparna@in.ibm.com
Cc: daniel@osdl.org, janetmor@us.ibm.com, pbadari@us.ibm.com,
       linux-aio@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH linux-2.6.0-test10-mm1] filemap_fdatawait.patch
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Andrew Morton <akpm@osdl.org> wrote:
>
> Let me actually think about this a bit.

Nasty.  The same race is present in 2.4.x...

How's about we start new I/O in filemap_fdatawait() if the page is dirty?


diff -puN mm/filemap.c~a mm/filemap.c
--- 25/mm/filemap.c~a	2003-12-31 03:10:29.000000000 -0800
+++ 25-akpm/mm/filemap.c	2003-12-31 03:17:05.000000000 -0800
@@ -206,7 +206,13 @@ restart:
 		page_cache_get(page);
 		spin_unlock(&mapping->page_lock);
 
-		wait_on_page_writeback(page);
+		lock_page(page);
+		if (PageDirty(page) && mapping->a_ops->writepage) {
+			write_one_page(page, 1);
+		} else {
+			wait_on_page_writeback(page);
+			unlock_page(page);
+		}
 		if (PageError(page))
 			ret = -EIO;