From: Karel Zak <kzak@redhat.com>
To: Goffredo Baroncelli <kreijack@inwind.it>
Cc: util-linux@vger.kernel.org,
linux-btrfs <linux-btrfs@vger.kernel.org>,
Chris Mason <chris.mason@fusionio.com>,
Chris Murphy <lists@colorremedies.com>
Subject: Re: Btrfs: wipe all the superblock [redhat bugzilla 889888]
Date: Tue, 8 Jan 2013 19:01:26 +0100 [thread overview]
Message-ID: <20130108180126.GB9177@x2.net.home> (raw)
In-Reply-To: <50E9C267.3050302@inwind.it>
On Sun, Jan 06, 2013 at 07:28:55PM +0100, Goffredo Baroncelli wrote:
> If the first superblock is valid except that the "magic field" is zeroed,
> btrfs skips the check of the other superblocks.
> If the first superblock is fully invalid, btrfs checks for the other
> superblock.
Hmm... why inconsistent (or missing) superblock is not reported as a
problem? If I good understand the filesystem is still mountable,
right?
> So zeroing the first superblock "magic field" at the beginning seems
> that the filesystem is wiped.
Well, this is exactly the idea behind wipefs(8), just wipe minimal
number of bytes from the device to make the filesystem invisible for
libblkid (udev, ...). This concept is relatively safe, if you make a
mistake than you can restore the magic string, your data should not
be affected by wipefs(8).
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
next prev parent reply other threads:[~2013-01-08 18:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-06 18:28 Btrfs: wipe all the superblock [redhat bugzilla 889888] Goffredo Baroncelli
2013-01-07 16:33 ` David Sterba
2013-01-07 18:20 ` Goffredo Baroncelli
2013-01-07 18:24 ` Hugo Mills
2013-01-07 18:33 ` Goffredo Baroncelli
2013-01-08 17:14 ` David Sterba
2013-01-08 15:48 ` Günter Gersdorf
2013-01-08 20:31 ` Goffredo Baroncelli
2013-01-09 8:09 ` Günter Gersdorf
2013-01-08 16:43 ` Karel Zak
2013-01-09 17:48 ` Goffredo Baroncelli
2013-01-09 18:10 ` Karel Zak
2013-01-08 18:01 ` Karel Zak [this message]
2013-01-08 20:09 ` Goffredo Baroncelli
2013-01-08 20:27 ` Chris Murphy
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