From: Valdis.Kletnieks@vt.edu
Subject: Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation
Date: Sun, 21 Nov 2010 14:07:04 -0500
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References: <1290065809-3976-1-git-send-email-lczerner@redhat.com> <20101118130630.GJ6178@parisc-linux.org> <20101118134804.GN5618@dhcp231-156.rdu.redhat.com> <20101118141957.GK6178@parisc-linux.org> <20101118142918.GA18510@infradead.org> <1290100750.3041.72.camel@mulgrave.site> <4CE59C9E.6050902@teksavvy.com> <1290177488-sup-6540@think>
            <4CE68F80.7000607@teksavvy.com>
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Cc: Chris Mason <chris.mason@oracle.com>,
	James Bottomley <james.bottomley@suse.de>,
	Christoph Hellwig <hch@infradead.org>,
	Matthew Wilcox <matthew@wil.cx>,
	Josef Bacik <josef@redhat.com>,
	Lukas Czerner <lczerner@redhat.com>, tytso <tytso@mit.edu>,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	sandeen <sandeen@redhat.com>
To: Mark Lord <kernel@teksavvy.com>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
In-Reply-To: Your message of "Fri, 19 Nov 2010 09:53:52 EST."
             <4CE68F80.7000607@teksavvy.com>
Sender: linux-fsdevel-owner@vger.kernel.org
List-Id: linux-ext4.vger.kernel.org

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On Fri, 19 Nov 2010 09:53:52 EST, Mark Lord said:
> On 10-11-19 09:40 AM, Chris Mason wrote:
> >
> > We've been told that online and constant trimming is the default in
> > windows7.   The ssds are most likely to just start ignoring the trims
> > they can't service efficiently.
> 
> Win7 collects multiple TRIM ranges over time and batches them as single TRIMs
> (as reported to me by an SSD vendor who traced it with a SATA analyzer,
>   and who also apparently has "inside info").

What should happen if we have (for instance) a "collect 64 trims at a time" policy,
and the system crashes at trim number 47? (Probably not an issue if you're
doing non-deterministic trim, but is an exposure if you're relying on deterministic
trim for security reasons)

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