Re: Loud "pop" coming from hard drive on reboot

From: Tejun Heo <htejun@gmail.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: 7eggert@gmx.de, Chuck Ebbert <cebbert@redhat.com>,
	emisca <emisca.ml@gmail.com>,
	Jan Engelhardt <jengelh@linux01.gwdg.de>,
	Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-ide@vger.kernel.org, Adrian Bunk <bunk@stusta.de>,
	Andrew Morton <akpm@osdl.org>
Subject: Re: Loud "pop" coming from hard drive on reboot
Date: Wed, 18 Apr 2007 22:05:57 +0900	[thread overview]
Message-ID: <462617B5.8050205@gmail.com> (raw)
In-Reply-To: <20070418140346.636879a1@the-village.bc.nu>

Alan Cox wrote:
>> Thought about that and querying power state before doing shutdown 
>> sequence but things get somewhat ugly because shutdown sequence is 
>> driven from sd->shutdown().  We'll have to snoop both sync and shutdown 
>> commands and check whether the system is shutting down.  Also, I felt 
>> very uneasy about faking successful completion to SYNCHRONIZE_CACHE.
> 
> If you see a synchronize cache succeed and you then see the drive
> shutdown succeed then you know that a sync cache can be faked as ok
> safely. Any other command in between or after and it doesn't get faked
> 
> This seems pretty easy to deal with at command issue.

Yeah, right.  I guess I'm too anal about SYNCHRONIZE_CACHE.

>> I dunno.  It's already too late for 2.6.21.  I was hoping we could get 
>> distros to update shutdown utilities in not-too-distant future but I 
>> have no experience with that.  Is that just a wishful thinking?
> 
> Probably not, but it will take a year or so and throughout this time
> period everyone with the wrong combination of shutdown and kernel (which
> will be a lot of people who compile their own kernels) are going to have
> problems caused by what is a very obscure piece of libata internal
> behaviour they'll never even know about.

Okay, will do another round of the patch.

Thanks.

-- 
tejun