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From: Theodore Tso <tytso@mit.edu>
To: Etienne Lorrain <etienne_lorrain@yahoo.fr>
Cc: Andreas Dilger <adilger@sun.com>, linux-ext4@vger.kernel.org
Subject: Re: on disk format: value of bg_inode_table_hi?
Date: Thu, 29 Jan 2009 00:12:22 -0500	[thread overview]
Message-ID: <20090129051221.GH8990@mit.edu> (raw)
In-Reply-To: <653674.25270.qm@web23601.mail.ird.yahoo.com>

On Wed, Jan 28, 2009 at 08:47:09PM +0000, Etienne Lorrain wrote:
> > De: Andreas Dilger <adilger@sun.com>
> > Date: Mercredi 28 Janvier 2009, 18h01
> > On Jan 28, 2009  00:20 +0000, Etienne Lorrain wrote:
> > > I have created an ext4 fs on a 64 Mb USB disk by
> > > "mkfs.ext4 /dev/sdb" on debian lenny (no partition).
> > > When I analyse the filesystem using my own tools, I
> > > seem to read at least some bg_inode_table_hi values which
> > > are not null, on such a very small filesystem.

bg_inode_table_hi doesn't exist on a small filesystem.  You need to
take a look at if INCOMPAT_64BIT is not set, or if INCOMPAT_64BIT is
set and s_desc_size is 32, then only the first 32 bytes of struct
ext4_group_desc are in use --- which look exactly the same as
ext2_group_desc.

So there is no problem here.  Just a misunderstanding of the
filesystem format.

						- Ted

  reply	other threads:[~2009-01-29  5:12 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-28  0:20 on disk format: value of bg_inode_table_hi? Etienne Lorrain
2009-01-28 18:01 ` Andreas Dilger
2009-01-28 20:47   ` Etienne Lorrain
2009-01-29  5:12     ` Theodore Tso [this message]
2009-01-29 11:47       ` Etienne Lorrain
2009-01-30  4:19         ` Theodore Tso

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