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Date: Fri, 21 Nov 2025 08:24:21 +0100
From: Christoph Hellwig <hch@lst.de>
To: Uladzislau Rezki <urezki@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>, Mikulas Patocka <mpatocka@redhat.com>,
	Benjamin Marzinski <bmarzins@redhat.com>,
	Alasdair Kergon <agk@redhat.com>, DMML <dm-devel@lists.linux.dev>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Snitzer <snitzer@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RESEND PATCH] dm-ebs: Mark full buffer dirty even on partial
 write
Message-ID: <20251121072421.GA29754@lst.de>
References: <20251117105945.10179-1-urezki@gmail.com> <fff990bc-6ff9-7b34-8e80-57078de40928@redhat.com> <aRxa1wPMsJwBubjx@pc636> <73556fc8-5fbf-37cb-26b9-7cdb88f69720@redhat.com> <aRx_lCimJco5BPKA@redhat.com> <230baa83-cd79-f232-5fb8-1476115e1ae7@redhat.com> <20251119054635.GB19993@lst.de> <bcd929c2-88b0-36e9-0e22-4bb0293300b5@redhat.com> <20251120062146.GA29990@lst.de> <aR8E2ZZtOi0RZt06@pc636>
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On Thu, Nov 20, 2025 at 01:08:57PM +0100, Uladzislau Rezki wrote:
> Could you please check below? Is the last one is correctly reported?

The latter looks unexpected, but is is becase qemu is not passing through
the qemu physical_block_size attribute to any of the nvme settings Linux
interprets as such for NVMe (NVMe doesn't actually have the concept of
a physical block size, unlike SCSI/ATA):

root@testvm:~# nvme id-ns -H /dev/nvme0n1 | grep npw
npwg    : 0
npwa    : 0
root@testvm:~# nvme id-ns -H /dev/nvme0n1 | grep naw
nawun   : 0
nawupf  : 0
root@testvm:~# nvme id-ctrl -H /dev/nvme0 | grep awupf
awupf     : 0

but as said multiple times, that should not really matter - the logical
block size is the granularity of I/O, the physical block size is just
a performance hint.