* [Libguestfs] Should we always do wipefs before mkfs? Discuss ...
@ 2013-02-04 18:23 Richard W.M. Jones
2013-02-05 9:20 ` Karel Zak
0 siblings, 1 reply; 3+ messages in thread
From: Richard W.M. Jones @ 2013-02-04 18:23 UTC (permalink / raw)
To: libguestfs; +Cc: berrange, kzak, util-linux
https://bugzilla.redhat.com/show_bug.cgi?id=907554
In particular comments 2 & 3.
We could change libguestfs's guestfs_mkfs (internally) so it always
does an implicit wipefs on the filesystem. wipefs is not too onerous --
in particular I believe it only writes to a few chosen areas of the
disk. Especially considering that we're about to run mkfs anyway
which for some filesystems writes a lot of blocks.
Thoughts?
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://libguestfs.org
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Libguestfs] Should we always do wipefs before mkfs? Discuss ...
2013-02-04 18:23 [Libguestfs] Should we always do wipefs before mkfs? Discuss Richard W.M. Jones
@ 2013-02-05 9:20 ` Karel Zak
2013-02-05 9:37 ` Richard W.M. Jones
0 siblings, 1 reply; 3+ messages in thread
From: Karel Zak @ 2013-02-05 9:20 UTC (permalink / raw)
To: Richard W.M. Jones; +Cc: libguestfs, berrange, util-linux
On Mon, Feb 04, 2013 at 06:23:38PM +0000, Richard W.M. Jones wrote:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=907554
All mkfs.<type> should be robust enough to wipe the device. I'm
currently working with guys around filesystems to improve mkfs.ext4
and mkfs.xfs
https://bugzilla.redhat.com/show_bug.cgi?id=902512
.. but nothing is perfect so explicitly call wipefs(8) from
installers or things like libguestfs is definitely good idea.
> We could change libguestfs's guestfs_mkfs (internally) so it always
> does an implicit wipefs on the filesystem. wipefs is not too onerous --
> in particular I believe it only writes to a few chosen areas of the
> disk. Especially considering that we're about to run mkfs anyway
> which for some filesystems writes a lot of blocks.
wipefs(8) (or blkid_do_wipe() from the library) wipes only magic
strings to make the filesystem (raids or partition tables) invisible
for libblkid. It means very few bytes.
> Thoughts?
Go ahead :-)
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [Libguestfs] Should we always do wipefs before mkfs? Discuss ...
2013-02-05 9:20 ` Karel Zak
@ 2013-02-05 9:37 ` Richard W.M. Jones
0 siblings, 0 replies; 3+ messages in thread
From: Richard W.M. Jones @ 2013-02-05 9:37 UTC (permalink / raw)
To: Karel Zak; +Cc: libguestfs, berrange, util-linux
On Tue, Feb 05, 2013 at 10:20:03AM +0100, Karel Zak wrote:
> On Mon, Feb 04, 2013 at 06:23:38PM +0000, Richard W.M. Jones wrote:
> >
> > https://bugzilla.redhat.com/show_bug.cgi?id=907554
>
> All mkfs.<type> should be robust enough to wipe the device. I'm
> currently working with guys around filesystems to improve mkfs.ext4
> and mkfs.xfs
>
> https://bugzilla.redhat.com/show_bug.cgi?id=902512
>
> .. but nothing is perfect so explicitly call wipefs(8) from
> installers or things like libguestfs is definitely good idea.
>
> > We could change libguestfs's guestfs_mkfs (internally) so it always
> > does an implicit wipefs on the filesystem. wipefs is not too onerous --
> > in particular I believe it only writes to a few chosen areas of the
> > disk. Especially considering that we're about to run mkfs anyway
> > which for some filesystems writes a lot of blocks.
>
> wipefs(8) (or blkid_do_wipe() from the library) wipes only magic
> strings to make the filesystem (raids or partition tables) invisible
> for libblkid. It means very few bytes.
>
> > Thoughts?
>
> Go ahead :-)
Thanks . That was my conclusion when I looked at the wipefs code in
blkid last night: it's worth trying it, but we won't fail the whole
operation if for some reason the wipefs fails.
Here is my patch:
https://github.com/libguestfs/libguestfs/commit/72dd398679cd0bb803daf306d12558369615ba70
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Fedora Windows cross-compiler. Compile Windows programs, test, and
build Windows installers. Over 100 libraries supported.
http://fedoraproject.org/wiki/MinGW
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-02-05 9:37 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-02-04 18:23 [Libguestfs] Should we always do wipefs before mkfs? Discuss Richard W.M. Jones
2013-02-05 9:20 ` Karel Zak
2013-02-05 9:37 ` Richard W.M. Jones
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox