From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
"Nicholas A. Bellinger" <nab@linux-iscsi.org>,
target-devel@vger.kernel.org,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [RFC] Simlify dif_verify routines and fixup fileio protection information code.
Date: Thu, 16 Apr 2015 11:30:20 -0400 [thread overview]
Message-ID: <yq1oamo2ir7.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <CAC5umygHt_LHyCWEhg9whhe7PfQBy=Y9uXbKAE6+1EL7MEzmrg@mail.gmail.com> (Akinobu Mita's message of "Thu, 16 Apr 2015 22:46:15 +0900")
>>>>> "Akinobu" == Akinobu Mita <akinobu.mita@gmail.com> writes:
>>> We don't issue WRITE SAME with PI so there is no prot SGL.
>> Is there a specific reason why we don't?
There really isn't much of a benefit when all you're doing is
replicating zeroes. So it hasn't been very high on my list.
Akinobu> It is not only for the WRITE SAME requests from block device
Akinobu> but also for READ/WRITE with PROTECT=0 requests by SG_IO.
Akinobu> So isn't is appropreate to allocate prot SGL in
Akinobu> target_write_prot_action() (and mark se_cmd->se_cmd_flags to
Akinobu> release it at deallocation time)?
Correct. Just because a target is formatted with PI does not mean that
every I/O it receives has PI attached. That's entirely driven by
RDPROTECT/WRPROTECT/VRPROTECT at the initiator's discretion.
It is an absolute requirement that the device, if formatted with PI,
will generate and write the correct protection information when
WRPROTECT is 0.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2015-04-16 15:30 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-13 17:19 [RFC] Simlify dif_verify routines and fixup fileio protection information code Sagi Grimberg
2015-04-13 17:19 ` [PATCH RFC 1/2] target: Merge sbc_verify_dif_read|write Sagi Grimberg
2015-04-13 17:19 ` [PATCH RFC 2/2] target/file: Remove fd_prot bounce buffer Sagi Grimberg
2015-04-14 1:23 ` [RFC] Simlify dif_verify routines and fixup fileio protection information code Martin K. Petersen
2015-04-14 12:17 ` Akinobu Mita
2015-04-14 17:20 ` Sagi Grimberg
2015-04-14 23:52 ` Akinobu Mita
2015-04-15 10:07 ` Sagi Grimberg
2015-04-15 14:16 ` Akinobu Mita
2015-04-15 14:33 ` Sagi Grimberg
2015-04-15 15:05 ` Martin K. Petersen
2015-04-15 15:08 ` Sagi Grimberg
2015-04-15 16:10 ` Martin K. Petersen
2015-04-16 8:52 ` Sagi Grimberg
2015-04-16 13:46 ` Akinobu Mita
2015-04-16 15:30 ` Martin K. Petersen [this message]
2015-04-16 15:58 ` Sagi Grimberg
2015-04-16 16:04 ` Sagi Grimberg
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