Subject: Re: [PATCH ] Fix some problems with truncate and mtime semantics.
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: NeilBrown <neilb@suse.de>
Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org
In-Reply-To: <1051115020002.9459@suse.de>
References: <20051115125657.9403.patches@notabene>
	 <1051115020002.9459@suse.de>
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Date: Mon, 14 Nov 2005 21:03:10 -0500
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On Tue, 2005-11-15 at 13:00 +1100, NeilBrown wrote:
> Resubmitting this patch to fix truncate/mtime semantics.  
> 
> It is against 2.6.14-mm2 and is probably suitable for 2.6.15, but can
> be held over to 2.6.16 if you are feeling cautious.
> 
> NeilBrown
> 
> ### Comments for Changeset
> 
> SUS requires that when truncating a file to the size that it currently
> is:
>   truncate and ftruncate should NOT modify ctime or mtime
>   O_EXCL SHOULD modify ctime and mtime.
    ^^^^^ O_CREAT ;-)

> Currently mtime and ctime are always modified on most local
> filesystems (side effect of ->truncate) or never modified (on NFS).
> 
> With this patch:
>   ATTR_CTIME|ATTR_MTIME are sent with ATTR_SIZE precisely when 
>     an update of these times is required whether size changes or not 
>     (via a new argument to do_truncate).  This allows NFS to do
>     the right thing for O_EXCL.
                          ^^^^^

Cheers,
  Trond

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