From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 69F6C1A72F; Fri, 12 Jan 2024 03:34:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dupFg3Ti" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA95AC433F1; Fri, 12 Jan 2024 03:34:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1705030473; bh=U2WlBkeflJvpAc1+F5XCZJzmPfGFvOUX0WGz15O93zo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=dupFg3TiYXHcowGOPj1VuQ3cF7htHd3EBTb9Ay8QOQAmTZiRTLyE4tTKAEOSvSW7N dgaDzJbm8IB0lmRkq0Jw0HOVkYfxSPh0WBQNjtMSQ4WzAE1iOBTIOIAdxTDoTTWk6t nDXAXJ0Vzk+XViDn0jrsLsfLI+ZYjA9AxyJIQrQP1pqEsUTg5562pQe6P+D0Ganmrd k5qn2OudwttBzD+LQ0EcRRsBoOPLLMjaFIjgVYByLAwJA81lEKoazKcko1Nb7/WAst +5Iln7STcahWXeD0uJnElg38mzczKBhC+Hj7yN8aQdYlJeBKArdRUAgf4VKKEJWxTq XxO9MOHAlw99g== Message-ID: <6fe89190-a8ff-47c3-a6c4-7d69296c9883@kernel.org> Date: Fri, 12 Jan 2024 12:34:30 +0900 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Report] blk-zoned/ZNS: non_power_of_2 of zone->len] Content-Language: en-US To: Ming Lei , Bart Van Assche Cc: linux-block@vger.kernel.org, Yi Zhang , John Meneghini , linux-nvme@lists.infradead.org, hch@lst.de, Keith Busch , "Martin K . Petersen" , "linux-scsi @ vger . kernel . org" References: <20503cd0-3a99-45bb-8374-40296a3cb92a@kernel.org> From: Damien Le Moal Organization: Western Digital Research In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/12/24 12:29, Ming Lei wrote: > On Fri, Jan 12, 2024 at 12:05:45PM +0900, Damien Le Moal wrote: >> On 1/12/24 10:13, Ming Lei wrote: >>> Hello Damien and Guys, >>> >>> Yi reported that the following failure: >>> >>> Oct 18 15:24:15 localhost kernel: nvme nvme4: invalid zone size:196608 for namespace:1 >>> Oct 18 15:24:33 localhost smartd[2303]: Device: /dev/nvme4, opened >>> Oct 18 15:24:33 localhost smartd[2303]: Device: /dev/nvme4, NETAPPX4022S173A4T0NTZ, S/N:S66NNE0T800169, FW:MVP40B7B, 4.09 TB >>> >>> Looks current blk-zoned requires zone->len to be power_of_2() since >>> commit: >>> >>> 6c6b35491422 ("block: set the zone size in blk_revalidate_disk_zones atomically") >>> >>> And the original power_of_2() requirement is from the following commit >>> for ZBC and ZAC. >>> >>> d9dd73087a8b ("block: Enhance blk_revalidate_disk_zones()") >>> >>> Meantime block layer does support non-power_of_2 chunk sectors limit. >> >> That is not true. It does. See blk_stack_limits which ahs: >> >> /* Set non-power-of-2 compatible chunk_sectors boundary */ >> if (b->chunk_sectors) >> t->chunk_sectors = gcd(t->chunk_sectors, b->chunk_sectors); >> >> and the absence of any check on the value of chunk_sectors in >> blk_queue_chunk_sectors(). > > I meant non-power_of_2 chunk sectors limit is supported, see > > 07d098e6bbad ("block: allow 'chunk_sectors' to be non-power-of-2") > > And device mapper uses that. > >> >>> The question is if there is such hard requirement for ZNS, and I can't see >>> any such words in NVMe Zoned Namespace Command Set Specification. >> >> No, there are no requirements in ZNS for the zone size to be a power of 2 number >> of sectors/LBAs. The same is also true for ZBC and ZAC (SCSI and ATA) SMR HDDs. >> The requirement for the zone size to be a power of 2 number of sectors is >> entirely in the kernel. The reason being that zoned block device support started >> with SMR HDDs which all had a zone size of 256 MB (and still do) and no user >> ever wanted anything else than that. So everything was coded with this >> requirement, as that allowed many nice things like bit-shift/mask arithmetic for >> conversions between zone number and sectors etc (and that of course is very >> efficient). > > Thanks for the clarification. > >> >>> So is it one NVMe firmware issue? or blk-zoned problem with too strict(power_of_2) >>> requirement on zone->len? >> >> It is the latter. There was a session at LSF/MM last year about this. I recall >> that the conclusion was that unless there is a strong user demand for non power >> of 2 zone size, we are not going to do anything about it. Because allowing >> non-power of 2 zone size has some serious consequences all over the place, >> including in FSes that natively support zoned devices. So relaxing that >> requirement is not trivial. > > Just saw Bart's work on supporting non-power_of_2 zone len: > > https://lore.kernel.org/linux-block/dc89c70e-4931-baaf-c450-6801c200c1d7@acm.org/ > > IMO FS support might be another topic, cause FS isn't the only user, > also without block layer support, the device isn't usable, not mention FS. And if the FS requires a power of 2 zone size, that will create fragmentation of the zoned device support: some devices will be usable with an FS, others not. Not nice at all. That is *not* something that exists today, for any block device. I am not very keen on going down such route. > Since non-power2 zoned device does exists, I'd suggest Bart to restart the > work and let linux cover more zoned devices(include non-power 2 zone). See above. Others (Keith, Christoph, Martin) may also have a different opinion. -- Damien Le Moal Western Digital Research