linux-ext4 - Re: ext2fs_block_iterate (e2, EXT2_RESIZE_INO, ...) => EXT2_ET_FILE_TOO

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Message-ID: <20110831152207.GB32582@thunk.org>
Date:	Wed, 31 Aug 2011 11:22:07 -0400
From:	Ted Ts'o <tytso@....edu>
To:	Ivan Shmakov <oneingray@...il.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: ext2fs_block_iterate (e2, EXT2_RESIZE_INO, ...) =>
 EXT2_ET_FILE_TOO_BIG?

On Wed, Aug 31, 2011 at 05:52:35PM +0700, Ivan Shmakov wrote:
> 	Curiosly enough, ext2fs_block_iterate () returns
> 	EXT2FS_BLOCK_ITERATE for EXT2_RESIZE_INO (the binary in question
> 	is statically linked against libext2fs, 1.41.12 debian 2):
> 
> (gdb) print ext2fs_block_iterate (e2, ino, 0, 0, db_add_block, (void *)sp)
> $13 = 2133571410
> (gdb) 
> 
> 	Is it because the blocks belonging to this inode aren't supposed
> 	to belong to the filesystem itself, I wonder?

It returned the error EXT2_ET_FILE_TOO_BIG.  From ext2_err.h, which
you can get from the build tree of e2fsprogs, in lib/ext2fs/ext2_err.h
(generated from lib/ext2fs/ext2_err.et):

#define EXT2_ET_FILE_TOO_BIG                     (2133571410L)

Yeah, the resize inode is a special case.  It is specially constructed
to reserve space for new block group descriptor blocks when doing an
online resize.  I would suggest for your purposes that you _not_
support the online-resizable file system feature, as it's unneeded
complexity (from what I understand of what you're going to be doing
with the file system).

Regards,

							- Ted

P.S. The code to create the reserved inode can be found in
lib/ext2fs/res_gdt.c, in ext2fs_create_resize_inode().
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