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Date: Tue, 19 Nov 2024 19:24:27 +0100
From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	Christian Brauner <brauner@kernel.org>,
	Sagi Grimberg <sagi@grimberg.me>,
	Kanchan Joshi <joshi.k@samsung.com>, Hui Qi <hui81.qi@samsung.com>,
	Nitesh Shetty <nj.shetty@samsung.com>, Jan Kara <jack@suse.cz>,
	Pavel Begunkov <asml.silence@gmail.com>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org,
	io-uring@vger.kernel.org
Subject: Re: [PATCH 14/15] nvme: enable FDP support
Message-ID: <20241119182427.GA20997@lst.de>
References: <20241119121632.1225556-1-hch@lst.de> <20241119121632.1225556-15-hch@lst.de> <ZzzWQFyq0Sv7cuHb@kbusch-mbp>
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On Tue, Nov 19, 2024 at 11:17:36AM -0700, Keith Busch wrote:
> > +	if (le32_to_cpu(configs[result.fdpcidx].nrg) > 1) {
> > +		dev_warn(ns->ctrl->device, "FDP NRG > 1 not supported\n");
> 
> Why not support multiple reclaim groups?

Can you come up with a sane API for that?  And can you find devices in
the wild that actually support it?

> > +	ns->head->runs = le64_to_cpu(configs[result.fdpcidx].runs);
> 
> The config descriptors are variable length, so you can't just index into
> it. You have to read each index individually to get the next index's offset.
> Something like:

Indeed.  The current code only works when the first config is selected.