linux-ext4 - Re: [PATCH] resize2fs: clear uninit BG if allocating from new group

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Message-ID: <20150917235524.GE10390@birch.djwong.org>
Date:	Thu, 17 Sep 2015 16:55:24 -0700
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] resize2fs: clear uninit BG if allocating from new group

On Thu, Sep 17, 2015 at 05:42:18PM -0500, Eric Sandeen wrote:
> If resize2fs_get_alloc_block() allocates from a BLOCK_UNINIT
> group, nothing clears the UNINIT flag, so it is skipped when we
> go to write out modified bitmaps.  This leads to post-resize2fs
> e2fsck errors; used blocks in UNINIT groups, not marked in the
> block bitmap.
> 
> This shamelessly cuts & pastes clear_block_uninit() into
> resize2fs.c, and my problem goes away.

Hmm... which test was it that exhibited this error?

> Signed-off-by: Eric Sandeen <sandeen@...hat.com>
> ---
> 
> I've kind of lost the thread on resize2fs lately, so maybe this is
> a hack job?  At least it highlights the issue, even if it's not
> quite right.  Passes "make check" here and seems ok to me...
> 
> Thanks,
> -Eric
> 
> diff --git a/resize/resize2fs.c b/resize/resize2fs.c
> index 07c6a0c..0f202bd 100644
> --- a/resize/resize2fs.c
> +++ b/resize/resize2fs.c
> @@ -1614,12 +1614,27 @@ static blk64_t get_new_block(ext2_resize_t rfs)
>  	}
>  }
>  
> +static void clear_block_uninit(ext2_filsys fs, dgrp_t group)
> +{
> +	if (!ext2fs_has_group_desc_csum(fs) ||
> +	    !(ext2fs_bg_flags_test(fs, group, EXT2_BG_BLOCK_UNINIT)))
> +		return;
> +
> +	/* uninit block bitmaps are now initialized in read_bitmaps() */
> +
> +	ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
> +	ext2fs_group_desc_csum_set(fs, group);
> +	ext2fs_mark_super_dirty(fs);
> +	ext2fs_mark_bb_dirty(fs);
> +}
> +
>  static errcode_t resize2fs_get_alloc_block(ext2_filsys fs,
>  					   blk64_t goal EXT2FS_ATTR((unused)),
>  					   blk64_t *ret)
>  {
>  	ext2_resize_t rfs = (ext2_resize_t) fs->priv_data;
>  	blk64_t blk;
> +	int group;
>  
>  	blk = get_new_block(rfs);
>  	if (!blk)
> @@ -1632,6 +1647,12 @@ static errcode_t resize2fs_get_alloc_block(ext2_filsys fs,
>  
>  	ext2fs_mark_block_bitmap2(rfs->old_fs->block_map, blk);
>  	ext2fs_mark_block_bitmap2(rfs->new_fs->block_map, blk);
> +
> +	group = ext2fs_group_of_blk2(rfs->old_fs, blk);
> +	clear_block_uninit(rfs->old_fs, group);

Why does the old fs need to have BLOCK_UNINIT cleared?

--D

> +	group = ext2fs_group_of_blk2(rfs->new_fs, blk);
> +	clear_block_uninit(rfs->new_fs, group);
> +
>  	*ret = (blk64_t) blk;
>  	return 0;
>  }
> 
> --
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