linux-ext4 - Re: [PATCH, E2FSPROGS] ext2fs_set_gdt_csum(): Force the last block group to have a valid block bitmap

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Message-ID: <20080331235204.GD11828@mit.edu>
Date:	Mon, 31 Mar 2008 19:52:04 -0400
From:	Theodore Tso <tytso@....EDU>
To:	linux-ext4@...r.kernel.org
Cc:	Andreas Dilger <adilger@...ger.ca>
Subject: Re: [PATCH, E2FSPROGS] ext2fs_set_gdt_csum(): Force the last block
	group to have a valid block bitmap

On Mon, Mar 31, 2008 at 07:36:26PM -0400, Theodore Ts'o wrote:
> From: Andreas Dilger <adilger@...ger.ca>
> 
> Never set the UNINIT_BLOCKS flag for the last group since the kernel
> doesn't handle the case graefully if there is a full set of blocks in
> each blockgroup marked UNINIT_BLOCKS.  The kernel should be fixed up,
> but in the meantime this avoids hitting the problem, and is more
> consistent with lazy_bg not marking the last group UNINIT.

This is technically not necessary since we will only set UNINIT_BLOCKS
if the number of free blocks is equal to blocks_per_group minus
superblock_overhead.  So there was no danger in the existing codepath.
I think you did this because you were enforcing no UNINIT_BLOCKS in
the last group in e2fsck, instead of just checking to make sure the
free blocks equals the return value from ext2fs_super_and_bgd_loc().

     	    	       	      	    	 - Ted
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