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From: Ted Ts'o <tytso@mit.edu>
To: Ivan Shmakov <oneingray@gmail.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: a (documented) way to get the Ext2+ filesystem size?
Date: Thu, 18 Aug 2011 17:03:13 -0400	[thread overview]
Message-ID: <20110818210313.GA4602@thunk.org> (raw)
In-Reply-To: <86ei0jxtt9.fsf@gray.siamics.net>

On Thu, Aug 18, 2011 at 10:49:38AM +0700, Ivan Shmakov wrote:
>  > For this, I'd suggest that you use the ext2fs library.  That will
>  > take care of byte swapping, etc.  It also means that you don't have
>  > to worry about parsing the extent trees.  If you had used the ext2fs
>  > library before ext4 had shipped, you wouldn't have had to make any
>  > changes to support extents, since the ext2fs library wraps and
>  > provides abstract interfaces for most of what you would need for
>  > e2dis project.
> 
> 	I don't seem to understand.  I've scanned through the
> 	(libext2fs.info) Function Index section (as per the Debian's
> 	e2fslibs-dev package, 1.41.12-2), and I see no mention of a
> 	function that I can use for that.

Sorry, the documentation is not necessarily complete; my apologies.

> 	Thus, I've ended up writing my own one, which takes an
> 	ext2_filsys handle, and references, via its ‘super’ member, the
> 	‘s_blocks_count’ and ‘s_blocks_count_hi’ members of the
> 	superblock structure.

The function to do this is in the 1.42 dev branch which is in Debian
unstable, and it's called ext2fs_block_count().

> 	However, I was concerned that I don't seem to find the
> 	documentation for these structures' contents anywhere.  (Sans
> 	the source, of course), and wondered, if the interface I use is
> 	at least stable?

I make a very strong effort to ensure that interfaces which are
exposed via the shared library are stable.  If you're not sure, please
feel free to ask on the ext4 list.

Regards,

					- Ted
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  reply	other threads:[~2011-08-18 21:03 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-16 11:37 a (documented) way to get the Ext2+ filesystem size? Ivan Shmakov
2011-08-16 14:21 ` Jan Kara
2011-08-17 18:31 ` Ted Ts'o
2011-08-17 18:50   ` Ivan Shmakov
2011-08-17 22:09     ` Ted Ts'o
2011-08-18  2:34       ` Steven Liu
2011-08-18  4:25         ` e2dis example usage pattern Ivan Shmakov
2011-08-18  3:49       ` a (documented) way to get the Ext2+ filesystem size? Ivan Shmakov
2011-08-18 21:03         ` Ted Ts'o [this message]
2011-08-19  4:34           ` Ivan Shmakov

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