From: Trond Myklebust <trond.myklebust@fys.uio.no>
Subject: Re: Why doesn't zap_pte_range() call page_mkwrite()
Date: Fri, 24 Apr 2009 10:06:58 -0400
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Cc: Miklos Szeredi <miklos@szeredi.hu>, npiggin@suse.de,  linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
To: Chris Mason <chris.mason@oracle.com>
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On Fri, 2009-04-24 at 09:31 -0400, Trond Myklebust wrote:
> The only alternative I can think of would be to unmap the page when the
> filesystem starts to write it out in order to force another page fault
> if the user application writes more data into that page.

Actually, this might be fairly trivial to implement in NFS. We'd tag the
nfs_page request as having been created by page_mkwrite(), then unmap
any such tagged page in the ->writepage() callback (assuming that
calling unmap_mapping_range() from ->writepage() is allowed?).

AFAICS that should get rid of those residual dirty ptes in sys_munmap().

Cheers
  Trond

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