From: Christoph Hellwig <hch@lst.de>
To: Caleb Sander Mateos <csander@purestorage.com>
Cc: Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@kernel.dk>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
Chaitanya Kulkarni <kch@nvidia.com>,
linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 5/7] nvme: set discard_granularity from NPDG/NPDA
Date: Tue, 24 Feb 2026 15:33:50 +0100 [thread overview]
Message-ID: <20260224143350.GC11710@lst.de> (raw)
In-Reply-To: <20260221033302.1451669-6-csander@purestorage.com>
On Fri, Feb 20, 2026 at 08:33:00PM -0700, Caleb Sander Mateos wrote:
> + if (ctrl->dmrsl && ctrl->dmrsl <= nvme_sect_to_lba(ns->head, UINT_MAX))
> + lim->max_hw_discard_sectors =
> + nvme_lba_to_sect(ns->head, ctrl->dmrsl);
> + else if (ctrl->oncs & NVME_CTRL_ONCS_DSM)
> + lim->max_hw_discard_sectors = UINT_MAX;
> + else
> + lim->max_hw_discard_sectors = 0;
> +
> + if (optperf & 0x2 && nvm && nvm->npdgl)
> + npdg = le32_to_cpu(nvm->npdgl);
> + else if (optperf & 0x1)
> + npdg = (u32)le16_to_cpu(id->npdg) + 1;
> + if (optperf & 0x2 && nvm && nvm->npdal)
> + npda = le32_to_cpu(nvm->npdal);
> + else if (optperf)
> + npda = (u32)le16_to_cpu(id->npda) + 1;
This code looks like black magic. This is mostly a fault of the spec for
using the weird matrix with unnamed values and the weird "0based" values.
Please add a comment referencing the figure in the spec that this
decodes. And maybe also a from0based helper mirroring to0based in nvmet.
next prev parent reply other threads:[~2026-02-24 14:33 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-21 3:32 [PATCH v2 0/7] nvme: set discard_granularity from NPDG/NPDA Caleb Sander Mateos
2026-02-21 3:32 ` [PATCH v2 1/7] nvme: add preferred I/O size fields to struct nvme_id_ns_nvm Caleb Sander Mateos
2026-02-21 3:32 ` [PATCH v2 2/7] nvme: fold nvme_config_discard() into nvme_update_disk_info() Caleb Sander Mateos
2026-02-24 14:29 ` Christoph Hellwig
2026-02-21 3:32 ` [PATCH v2 3/7] nvme: update nvme_id_ns OPTPERF constants Caleb Sander Mateos
2026-02-24 14:30 ` Christoph Hellwig
2026-02-21 3:32 ` [PATCH v2 4/7] nvme: always issue I/O Command Set specific Identify Namespace Caleb Sander Mateos
2026-02-21 3:33 ` [PATCH v2 5/7] nvme: set discard_granularity from NPDG/NPDA Caleb Sander Mateos
2026-02-24 14:33 ` Christoph Hellwig [this message]
2026-02-24 15:15 ` Keith Busch
2026-02-24 16:05 ` Caleb Sander Mateos
2026-02-21 3:33 ` [PATCH v2 6/7] nvmet: use NVME_NS_FEAT_OPTPERF_SHIFT Caleb Sander Mateos
2026-02-21 3:33 ` [PATCH v2 7/7] nvmet: report NPDGL and NPDAL Caleb Sander Mateos
2026-02-24 14:34 ` Christoph Hellwig
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