From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Keith Busch <kbusch@kernel.org>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
Christoph Hellwig <hch@lst.de>,
sagi@grimberg.me, linux-nvme@lists.infradead.org
Subject: Re: [PATCH] nvme: implement the DEAC bit for the Write Zeroes command
Date: Mon, 31 Oct 2022 11:48:08 -0400 [thread overview]
Message-ID: <yq17d0gq9oq.fsf@ca-mkp.ca.oracle.com> (raw)
In-Reply-To: <Y1/kw75JaNsnt1iy@kbusch-mbp.dhcp.thefacebook.com> (Keith Busch's message of "Mon, 31 Oct 2022 09:07:47 -0600")
Keith,
> The device must return all 0's for the range covered by a write zeroes
> command no matter what. The controller shall not deallocate the
> logical blocks if it can't guarantee reading deallocated blocks will
> return 0's, so I think it's okay to skip checking the lower dlfeat
> bits.
The spec is sufficiently vague for the does-not-return-zeroes case that
I'm concerned about "shall not deallocate" being interpreted by vendors
as "free to ignore" based on past ATA/SCSI experience.
But we can always quirk it. Devices that return all-Fs are rare.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2022-10-31 15:48 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 [this message]
2022-11-01 9:58 ` Christoph Hellwig
2022-11-01 15:49 ` Martin K. Petersen
2022-11-04 7:06 ` Christoph Hellwig
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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