From: Keith Owens <kaos@ocs.com.au>
To: linux-kernel@vger.kernel.org
Subject: 2.4.18 no timestamp update on modified mmapped files
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Date: Tue, 11 Jun 2002 15:33:48 +1000
Message-ID: <10339.1023773628@kao2.melbourne.sgi.com>
Sender: linux-kernel-owner@vger.kernel.org

fd = open("foo", O_RDWR);
map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
... modify the mapped pages ...
munmap(map, size);
close(fd);

The timestamp on foo is not updated, even though the contents have
changed.  Adding msync(map, size, MS_[A]SYNC) before munmap makes no
difference.  2.4.19-pre10 has no obvious fixes for this problem.

I was tearing my hair out wondering why some files were not being
rsynced.  No change on size or timestamp tells rsync that the file is
"unchanged".  I had to add a dummy write(map, fd, 1) to force a
timestamp update.

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