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Date: Mon, 22 Jan 2024 19:38:57 +0100
From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Damien Le Moal <dlemoal@kernel.org>,
	Sagi Grimberg <sagi@grimberg.me>, linux-block@vger.kernel.org,
	linux-nvme@lists.infradead.org, virtualization@lists.linux.dev
Subject: Re: [PATCH 05/15] block: add a max_user_discard_sectors queue limit
Message-ID: <20240122183857.GA7029@lst.de>
References: <20240122173645.1686078-1-hch@lst.de> <20240122173645.1686078-6-hch@lst.de> <Za6zg-pA8IJkIb_b@kbusch-mbp.dhcp.thefacebook.com>
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On Mon, Jan 22, 2024 at 11:27:15AM -0700, Keith Busch wrote:
> > +	q->limits.max_user_discard_sectors = max_discard_bytes >> SECTOR_SHIFT;
> > +	q->limits.max_discard_sectors =
> > +		min_not_zero(q->limits.max_hw_discard_sectors,
> > +			     q->limits.max_user_discard_sectors);
> 
> Shouldn't writing 0 disable discards?

I mirror the max_user_sectors behavior here, where 0 disables the
user limiting.  But yes, that would be a behavior change.