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Date: Tue, 10 Dec 2024 08:12:53 +0100
From: Christoph Hellwig <hch@lst.de>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Nitesh Shetty <nj.shetty@samsung.com>,
	Bart Van Assche <bvanassche@acm.org>,
	Javier Gonzalez <javier.gonz@samsung.com>,
	Matthew Wilcox <willy@infradead.org>,
	Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>,
	Keith Busch <kbusch@meta.com>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"io-uring@vger.kernel.org" <io-uring@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"joshi.k@samsung.com" <joshi.k@samsung.com>
Subject: Re: [PATCHv10 0/9] write hints with nvme fdp, scsi streams
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On Thu, Dec 05, 2024 at 03:37:25PM -0500, Martin K. Petersen wrote:
> The problem with option 2 is that when you're doing copy between two
> different LUNs, then you suddenly have to maintain state in one kernel
> object about stuff relating to another kernel object. I think that is
> messy. Seems unnecessarily complex.

Generally agreeing with all you said, but do we actually have any
serious use case for cross-LU copies?  They just seem incredibly
complex any not all that useful.