From owner-freebsd-fs@FreeBSD.ORG  Mon Aug 13 08:44:47 2012
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To: Konstantin Belousov <kostikbel@gmail.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 13 Aug 2012 11:41:20 +0300."
	<20120813084120.GA2352@deviant.kiev.zoral.com.ua>
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Date: Mon, 13 Aug 2012 08:44:36 +0000
Message-ID: <48610.1344847476@critter.freebsd.dk>
Cc: freebsd-fs@freebsd.org, Petri Helenius <petri@helenius.fi>
Subject: Re: zero deleted blocks
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In message <20120813084120.GA2352@deviant.kiev.zoral.com.ua>, Konstantin Belous
ov writes:

>I think TRIM support in UFS can be extended to zero-out the deleted
>blocks, with relatively small amount of work. Basically, in
>ufs/ffs/ffs_alloc.c:ffs_blkfree(), a BIO_WRITE of zero buffer shall be
>issued instead of BIO_DELETE.

It would be a better idea to give geom_disk a per-disk option to
convert BIO_DELETE to writes of zeros.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.