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From: Mikulas Patocka <mpatocka@redhat.com>
To: Damien Le Moal <Damien.LeMoal@wdc.com>
Cc: "dm-devel@redhat.com" <dm-devel@redhat.com>,
	Mike Snitzer <snitzer@redhat.com>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	Christoph Hellwig <hch@lst.de>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
	Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
	Milan Broz <mbroz@redhat.com>
Subject: Re: [dm-devel] [PATCH v2 0/3] Fix dm-crypt zoned block device support
Date: Mon, 19 Apr 2021 09:55:17 -0400 (EDT)
Message-ID: <alpine.LRH.2.02.2104190951070.17565@file01.intranet.prod.int.rdu2.redhat.com> (raw)
In-Reply-To: <BL0PR04MB65147D94E7E30C3E1063A282E7499@BL0PR04MB6514.namprd04.prod.outlook.com>



On Mon, 19 Apr 2021, Damien Le Moal wrote:

> > I would say that it is incompatible with all dm targets - even the linear 
> > target is changing the sector number and so it may redirect the write 
> > outside of the range specified in dm-table and cause corruption.
> 
> DM remapping of BIO sectors is zone compatible because target entries must be
> zone aligned. In the case of zone append, the BIO sector always point to the
> start sector of the target zone. DM sector remapping will remap that to another
> zone start as all zones are the same size. No issue here. We extensively use
> dm-linear for various test environment to reduce the size of the device tested
> (to speed up tests). I am confident there are no problems there.
> 
> > Instead of complicating device mapper with imperfect support, I would just 
> > disable REQ_OP_ZONE_APPEND on device mapper at all.
> 
> That was my initial approach, but for dm-crypt only since other targets that
> support zoned devices are fine. However, this breaks zoned block device
> requirement that zone append be supported so that users are presented with a
> uniform interface for different devices. So while simple to do, disabling zone
> append is far from ideal.

So, we could enable it for the linear target and disable for all other 
targets?

I talked with Milan about it and he doesn't want to add more bloat to the 
crypt target. I agree with him.

Mikulas


  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-17  2:33 Damien Le Moal
2021-04-17  2:33 ` [PATCH v2 1/3] dm: Introduce zone append support control Damien Le Moal
2021-04-17  2:33 ` [PATCH v2 2/3] dm crypt: Fix zoned block device support Damien Le Moal
2021-04-17 10:39   ` Johannes Thumshirn
2021-04-18 11:00   ` [dm-devel] " Milan Broz
2021-04-17  2:33 ` [PATCH v2 3/3] zonefs: fix synchronous write to sequential zone files Damien Le Moal
2021-04-19  6:45   ` Christoph Hellwig
2021-04-19  7:08     ` Damien Le Moal
2021-04-19  7:10       ` Christoph Hellwig
2021-04-20  1:20     ` Douglas Gilbert
2021-04-20  1:35       ` Damien Le Moal
2021-04-19 12:52 ` [dm-devel] [PATCH v2 0/3] Fix dm-crypt zoned block device support Mikulas Patocka
2021-04-19 13:02   ` Damien Le Moal
2021-04-19 13:55     ` Mikulas Patocka [this message]
2021-04-19 14:31       ` Milan Broz

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