Date: Tue, 12 Aug 2003 04:06:29 +0100
From: viro@parcelfarce.linux.theplanet.co.uk
To: Andries Brouwer <aebr@win.tue.nl>
Cc: Neil Brown <neilb@cse.unsw.edu.au>, Christoph Hellwig <hch@infradead.org>,
       Linus Torvalds <torvalds@osdl.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2 of 2 - Allow O_EXCL on a block device to claim exclusive use.
Message-ID: <20030812030629.GB454@parcelfarce.linux.theplanet.co.uk>
References: <E19m2XN-0002BU-00@notabene> <20030811082231.A20077@infradead.org> <16184.18284.969212.342794@gargle.gargle.HOWL> <20030812045610.B1650@pclin040.win.tue.nl>
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On Tue, Aug 12, 2003 at 04:56:10AM +0200, Andries Brouwer wrote:
> On Tue, Aug 12, 2003 at 11:48:28AM +1000, Neil Brown wrote:
> 
> > My first attempt at this did claim before openning.
> > However that didn't work.
> > Some aspects of the bdev that are needed for claiming are not
> > initialised before it is first opened.  In particular, bd_contains,
> > gets set up by do_open.
> 
> Size and structure of partitions are entirely independent of whether
> someone has opened them. Thus, the corresponding bookkeeping must
> not be in struct block_device, which exists only when the device
> is open, but in struct gendisk or so (and only there).
> 
> It is a design mistake to have such stuff in struct block device.

WTF does it have to do with ->bd_contains?  We *do* have the information
you (and nobody else in this thread) are talking about - in gendisk.
Exclusion upon open, OTOH, has something with opening these beast, won't
you agree?
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