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From: Theodore Ts'o <tytso@mit.edu>
To: Azat Khuzhin <a3at.mail@gmail.com>
Cc: linux-ext4@vger.kernel.org, chintzung@gmail.com
Subject: Re: tune2fs: update journal super block when changing UUID for fs.
Date: Sat, 5 Jul 2014 22:49:45 -0400	[thread overview]
Message-ID: <20140706024945.GA25768@thunk.org> (raw)
In-Reply-To: <1403965786-14561-1-git-send-email-a3at.mail@gmail.com>

On Sat, Jun 28, 2014 at 06:29:46PM +0400, Azat Khuzhin wrote:
> 
> Here is the RFC patch for this, I'm not sure about the check for *is this 
> journal device or not*, so I will glad to see some comments. Thanks.

The way you tell whether or not you've opened the journal device is as
follows:

	if (fs->super->s_feature_incompat & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
	   ...

That is to say, the journal device has a ext2/3/4 superblock, but with
a special incompat flag which indicates that it is an external journal
--- and which also prevents the kernel from trying to mount the
external journal device as a normal ext4 file system.

Regards,

					- Ted

      reply	other threads:[~2014-07-06  2:49 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-28 14:29 [PATCH] tune2fs: update journal super block when changing UUID for fs Azat Khuzhin
2014-07-06  2:49 ` Theodore Ts'o [this message]

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