linux-kernel - Re: [PATCH 2/4] AFS: Add a function to excise a rejected write from the pagecache

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Message-ID: <10564.1180521323@redhat.com>
Date:	Wed, 30 May 2007 11:35:23 +0100
From:	David Howells <dhowells@...hat.com>
To:	Trond Myklebust <trond.myklebust@....uio.no>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] AFS: Add a function to excise a rejected write from the pagecache

Trond Myklebust <trond.myklebust@....uio.no> wrote:

> All I do is to protect new calls to read() and write() with a call to
> check if the page cache needs invalidating.

What about mmap()?  What if someone gets a mapping on a section of file that
subsequently has a write rejected on it?  If you invalidate only on
read()/write(), what do you do about such a mapping?

> That won't stop any existing append writes from punching ugly holes into the
> file, but trying to recover from that sort of thing would be _really_
> painful!

Definitely.

David
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