From: Nick Dokos <nicholas.dokos@hp.com>
Subject: Re: Query regarding ext4 filesystem
Date: Thu, 25 Nov 2010 10:37:53 -0500
Message-ID: <1805.1290699473@gamaville.dokosmarshall.org>
References: <4CEE0225.6010205@tataelxsi.co.in>
Reply-To: nicholas.dokos@hp.com
Cc: linux-ext4@vger.kernel.org, nicholas.dokos@hp.com
To: Nivedita J N <niveditajn@tataelxsi.co.in>
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In-reply-to: Message from Nivedita J N <niveditajn@tataelxsi.co.in> of
 "Thu, 25 Nov 2010 11:58:53 +0530." <4CEE0225.6010205@tataelxsi.co.in>
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>    I'm planning to use ext4 filesystem in my ubuntu machine.I am doing
> a detailed search on the filesystem.I would like to know where the
> journal is stored in ext4 file system? Is it visible?
> 

You can use debugfs for this - do ``man 8 debugfs'' for more info. The
journal is generally inode 8 (you can do

    dumpe2fs -h /dev/FOO | grep "Journal inode:"

to make sure), so in debugfs you can do

    stat <8>
    ex <8>

to get metadata (size, perms, etc.) and extent information and

    logdump <OPTIONS>

to examine the contents of the journal - see the debugfs man page
for <OPTIONS> info.

HTH,
Nick