From: Christoph Hellwig <hch@lst.de>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>, Keith Busch <kbusch@kernel.org>,
sagi@grimberg.me, linux-nvme@lists.infradead.org
Subject: Re: [PATCH] nvme: implement the DEAC bit for the Write Zeroes command
Date: Fri, 4 Nov 2022 08:06:17 +0100 [thread overview]
Message-ID: <20221104070617.GB17463@lst.de> (raw)
In-Reply-To: <yq1v8nypu8w.fsf@ca-mkp.ca.oracle.com>
On Tue, Nov 01, 2022 at 11:49:06AM -0400, Martin K. Petersen wrote:
> Yep, but many device vendors messed that up due to the initial ambiguity
> in the spec wrt. how to handle the UNMAP flag. Based on experience with
> the SCSI UNMAP command being able to ignore blocks and ATA DSM TRIM
> being non-deterministic, several vendors ended up not treating WRITE
> SAME with the UNMAP flag set as a data integrity operation.
Uh.
> I was just concerned that this practice would carry over to NVMe. Bits
> 2:0 being set to 1 is an indication that somebody at least thought about
> this scenario during device implementation. But again, devices that
> return non-zero blocks after deallocate are rare and we can always quirk
> them if there's a problem.
I'm fine with adding the dlfeat check - it is trivial and if the bits
aren't set, sending the DEAC bit would be pointless anyway. It'll just
make the people asking for names for the unnamed bits even more unhappy..
next prev parent reply other threads:[~2022-11-04 7:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-30 16:29 [PATCH] nvme: implement the DEAC bit for the Write Zeroes command Christoph Hellwig
2022-10-31 9:01 ` Guixin Liu
2022-10-31 14:43 ` Pankaj Raghav
2022-10-31 14:54 ` Martin K. Petersen
2022-10-31 15:07 ` Keith Busch
2022-10-31 15:48 ` Martin K. Petersen
2022-11-01 9:58 ` Christoph Hellwig
2022-11-01 15:49 ` Martin K. Petersen
2022-11-04 7:06 ` Christoph Hellwig [this message]
2022-11-01 9:59 ` Christoph Hellwig
2022-11-02 10:46 ` Niklas Cassel
2022-11-02 15:56 ` Chaitanya Kulkarni
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