lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [day] [month] [year] [list]
Date:	Wed, 12 Jun 2013 08:52:25 -0400
From:	Theodore Ts'o <>
To:	Felipe Monteiro de Carvalho <>
Cc:	Autif Khan <>,
Subject: Re: How to differentiate ext4 from ext2/3 in code?

On Wed, Jun 12, 2013 at 07:00:57AM +0200, Felipe Monteiro de Carvalho wrote:
> Hello,
> Thanks a lot, it was a really good answer =) Just to complement I see that
> some software out there uses EXT4_FEATURE_INCOMPAT_EXTENTS in the incompat
> list. It seams that this flag is usually (always?) set in ext4 but never
> (?) present in ext3
> example:

It is true that the extents feature is supported by the ext4 file
system driver, and there exists no versions of the file system drivers
in the Linux kernel which supports the extents feature.

You can certainly construct file systems which have, say, the flex_bg
feature enabled has the same characteristics as the extents feature in
terms of support coverage by ext3 and ext4 implementations in the
Linux kernel, however.

It looks from the patch you've cited that parted is using some
hueristics for the purposes of displaying "ext2" vs "ext3" vs "ext4"
to the user.  That's fine from the perspective of simplifying the user
interface, but it can end up confusing the user for some unusual file
system configurations.


					- Ted
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists