From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Sitsofe Wheeler <sitsofe@yahoo.com>
Cc: Shaohua Li <shli@fb.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
snitzer@redhat.com, axboe@fb.com, martin.petersen@oracle.com,
Kernel-team@fb.com
Subject: Re: [PATCH] block: correctly fallback for zeroout
Date: Thu, 02 Jun 2016 22:56:05 -0400 [thread overview]
Message-ID: <yq1lh2nrnei.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <20160527054918.GA9521@sucs.org> (Sitsofe Wheeler's message of "Fri, 27 May 2016 06:49:21 +0100")
>>>>> "Sitsofe" == Sitsofe Wheeler <sitsofe@yahoo.com> writes:
Sitsofe> The original SCSI WRITE SAME has overloaded semantics - not
Sitsofe> only does it mean "write this data multiple times" but it can
Sitsofe> also be used to mean "discard this range" too. If the kernel's
Sitsofe> command was modelled on the SCSI original perhaps this
Sitsofe> conflation clouded things?
REQ_WRITE_SAME in the context of the kernel explicitly means "write
payload to this block range".
A REQ_DISCARD command may be serviced using WRITE SAME(16) with the
UNMAP bit set in the SCSI disk driver but that's entirely orthogonal.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2016-06-03 2:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-26 18:08 [PATCH] block: correctly fallback for zeroout Shaohua Li
[not found] ` <20160527054918.GA9521@sucs.org>
2016-05-28 9:27 ` Sitsofe Wheeler
2016-06-02 16:58 ` Shaohua Li
2016-06-02 17:02 ` Martin K. Petersen
2016-06-03 2:56 ` Martin K. Petersen [this message]
2016-05-29 6:47 ` Christoph Hellwig
2016-06-03 3:06 ` Martin K. Petersen
2016-06-03 3:54 ` Mike Snitzer
2016-06-07 2:32 ` Martin K. Petersen
2016-06-07 6:38 ` Christoph Hellwig
2016-06-10 2:05 ` Martin K. Petersen
2016-06-03 3:26 ` [PATCH] " Martin K. Petersen
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