From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 106861] New: DPOFUA should not be related to WCE / Caching mode
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Date: Thu, 29 Oct 2015 08:14:51 +0000
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https://bugzilla.kernel.org/show_bug.cgi?id=106861
Bug ID: 106861
Summary: DPOFUA should not be related to WCE / Caching mode
page
Product: IO/Storage
Version: 2.5
Kernel Version: 4.2.4
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: SCSI
Assignee: linux-scsi@vger.kernel.org
Reporter: tom.ty89@gmail.com
Regression: No
The sd driver checks whether the device supports DPO/FUA and reports it to the
FUA readonly attribute. However, they are somehow "depended" on the Caching
mode page and WCE (sd.c).
The fact is, the DPOFUA bit just isn't part of the Caching mode page. Instead
it is reported in DEVICE-SPECIFIC PARAMETER of mode parameter header.
Moreover, I don't see what impact does WCE have on DPO/FUA as per SBC or SAT.
As long as it is implemented correctly, DPO/FUA should be completely fine on
drives without write cache as well.
So IMHO how the kernel handles the checking and reporting simply has logical
mistake.
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