From mboxrd@z Thu Jan  1 00:00:00 1970
From: mulyadi.santosa@gmail.com (Mulyadi Santosa)
Date: Wed, 27 Apr 2011 00:22:55 +0700
Subject: block request execution failing on RHEL6.0 (2.6.32-71.el6.x86_64)
In-Reply-To: <BANLkTi=LLZnKod1M3DubXjqVCroOjmf3gw@mail.gmail.com>
References: <BANLkTimpWXJtcH03Dc3uyddAQLeDkT6cfw@mail.gmail.com>
	<BANLkTi=LLZnKod1M3DubXjqVCroOjmf3gw@mail.gmail.com>
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To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

On Wed, Apr 27, 2011 at 00:12, ajit jain <ajit4mail@gmail.com> wrote:
> Hi All,
>
> I have found the issue.
>
> in kernel prior to RHEL 6.0 blk_pc_request(rq) is define as:
> #define blk_pc_request(rq)????? ((rq)->flags & REQ_BLOCK_PC)
> while in RHEL 6.0 it is define as:
> #define blk_pc_request(rq)????? ((rq)->cmd_type == REQ_TYPE_BLOCK_PC)
>
> So, the issue was adding I was REQ_NOMERGE flag in cmd_type field of the
> request. This was making blk_pc_request(rq) to return false and thats why
> IOs were not going to scsi layer.

Wow, great research! May I suggest something? I think you need to
inform this bug to RHEL kernel team.... quite likely it's a serious
regression.
-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com