Date: Sat, 9 May 2015 09:00:26 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Matias Bj??rling <m@bjorling.me>
Cc: hch@infradead.org, axboe@fb.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        keith.busch@intel.com, javier@paletta.io
Subject: Re: [PATCH v3 2/7] block: add REQ_NVM_GC for targets gc
Message-ID: <20150509160026.GB16058@infradead.org>
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On Wed, Apr 22, 2015 at 04:26:51PM +0200, Matias Bj??rling wrote:
> In preparation for Open-Channel SSDs. We introduce a special request for
> open-channel ssd targets that must perform garbage collection.
> 
> Requests are divided into two types. The user and target specific. User
> IOs are from fs, user-space, etc. While target specific are IOs that are
> issued in the background by targets. Usually garbage collection actions.
> 
> For the target to issue garbage collection requests, it is a requirement
> that a logical address is locked over two requests. One read and one
> write. If a write to the logical address comes in from user-space, a
> race-condition might occur and garbage collection will write out-dated
> data.
> 
> By introducing this flag, the target can manually control locking of
> logical addresses.

Seems like this should be a new ->cmd_type instead of a flag.
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