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Date: Thu, 9 Jul 2009 09:37:46 -0400
From: Christoph Hellwig <hch@infradead.org>
To: Tejun Heo <tj@kernel.org>
Cc: Boaz Harrosh <bharrosh@panasas.com>, Jens Axboe <jens.axboe@oracle.com>,
       Linux Kernel <linux-kernel@vger.kernel.org>,
       James Bottomley <James.Bottomley@HansenPartnership.com>,
       linux-scsi <linux-scsi@vger.kernel.org>,
       Niel Lambrechts <niel.lambrechts@gmail.com>,
       FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
       Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 2/4] block: use the same failfast bits for bio and
	request
Message-ID: <20090709133746.GA21929@infradead.org>
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On Thu, Jul 09, 2009 at 09:45:24AM +0900, Tejun Heo wrote:
> What's more disturbing to me is the different between RQ and BIO
> flags.  __REQ_* are bit positions, REQ_* are masks while BIO_* are bit
> positions.  Sadly it seems it's already too late to change that.  I
> personally an not a big fan of simple accessors or flags defined as
> bit positions.  They seem to obscure things without much benefit.

flags as bit positions generally only make sense if you use
test/set/clear_bit, otherwise they just confuse things.  And the
accessors are pretty annoying, especially in the block layer.  Trying to
find the places where a BIO flag has an actual effect is pretty painful
due to the mix of the different flags and the accessors.