linux-kernel - Re: [RESEND PATCH] dm-ebs: Mark full buffer dirty even on partial write

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Message-ID: <aRxa1wPMsJwBubjx@pc636>
Date: Tue, 18 Nov 2025 12:39:03 +0100
From: Uladzislau Rezki <urezki@...il.com>
To: Mikulas Patocka <mpatocka@...hat.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@...il.com>,
	Alasdair Kergon <agk@...hat.com>, DMML <dm-devel@...ts.linux.dev>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mike Snitzer <snitzer@...hat.com>, Christoph Hellwig <hch@....de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH] dm-ebs: Mark full buffer dirty even on partial
 write

Hello, Mikulas!

> Hi
> 
> What is the logical_block_size of the underlying nvme device? - i.e. 
> what's the content of this file 
> /sys/block/nvme0n1/queue/logical_block_size in the virtual machine?
> 
It is 512. Whereas a physical is bigger, i.e. my device can not perform
I/O by 512 granularity.

As for virtual machine, i just simulated the problem so people can set
it up and check. The commit message describes how it can be reproduced.

The dm-ebs target which i setup does ebs to ubs conversion, so the NVME
driver gets BIOs are in size and aligned to ubs size. The ubs size
corresponds to the underlying physical device I/O size.

So your patch does not work if logical < physical. Therefore it does
not help my project.

--
Uladzislau Rezki