linux-ext4 - Re: [PATCH 1/2] libext2fs: Prevent allocating inode table from already used blocks

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Date:   Thu, 12 Oct 2017 15:54:31 +0200
From:   Lukas Czerner <lczerner@...hat.com>
To:     linux-ext4@...r.kernel.org
Cc:     tytso@....edu
Subject: Re: [PATCH 1/2] libext2fs: Prevent allocating inode table from
 already used blocks

Hi Ted,

this patchset is sitting here with no response on the list for almost
two months now. Do yo have any comments ? What I can do to move this
forward ? We have real customers hitting this issue and given our
"upstream first" policy we're waiting for your response.

Thanks!
-Lukas

On Thu, Aug 24, 2017 at 03:35:38PM +0200, Lukas Czerner wrote:
> Currently it's possible for ext2fs_allocate_group_table() to place inode
> tables to blocks that are already occupied by different inode table.
> This can be reproduced by resize2fs on the file system where we need to
> move more than one inode table to a different location due to increase
> in group descriptor blocks, inode and block bitmaps.
> 
> Best way I can reproduce this is to create big enough file system with
> huge amount of inodes and without resize_inode
> 
> mke2fs -F -b 1024 -i 1024 -O ^resize_inode -t ext4 /dev/loop0 1024000
> resize2fs /dev/loop0 10240000
> 
> e2fsck -fn /dev/loop0 | less
> e2fsck 1.43.5 (04-Aug-2017)
> ext2fs_check_desc: Corrupt group descriptor: bad block for inode table
> e2fsck: Group descriptors look bad... trying backup blocks...
> e2fsck: The journal superblock is corrupt while checking journal for /dev/loop0
> e2fsck: Cannot proceed with file system check
> Superblock has an invalid journal (inode 8).
> Clear? no
> 
> /dev/loop0: ********** WARNING: Filesystem still has errors **********
> 
> None of the settings are strictly necessary and it can be reproducer in
> various ways. This is just an example of one easy way to reproduce this.
> 
> This bug was introduced with commit fccdbac39454 ("libext2fs: optimize
> ext2fs_allocate_group_table()") and is caused by the fact that wrong
> bitmap is used to mark the blocks as used.
> 
> Fix this by using ext2fs_mark_block_bitmap_range2() in both (flex_bg and
> non flex_bg) cases and handle flex_bg case manually instead of relying
> on ext2fs_block_alloc_stats_range() because there is no way in that
> function to use different bitmap than fs->block_map.
> 
> Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> ---
>  lib/ext2fs/alloc_tables.c | 32 ++++++++++++++++++++++++++------
>  1 file changed, 26 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/ext2fs/alloc_tables.c b/lib/ext2fs/alloc_tables.c
> index da0b15b..407283f 100644
> --- a/lib/ext2fs/alloc_tables.c
> +++ b/lib/ext2fs/alloc_tables.c
> @@ -222,12 +222,32 @@ errcode_t ext2fs_allocate_group_table(ext2_filsys fs, dgrp_t group,
>  						bmap, &new_blk);
>  		if (retval)
>  			return retval;
> -		if (flexbg_size)
> -			ext2fs_block_alloc_stats_range(fs, new_blk,
> -				       fs->inode_blocks_per_group, +1);
> -		else
> -			ext2fs_mark_block_bitmap_range2(fs->block_map,
> -					new_blk, fs->inode_blocks_per_group);
> +
> +		ext2fs_mark_block_bitmap_range2(bmap,
> +			new_blk, fs->inode_blocks_per_group);
> +		if (flexbg_size) {
> +			blk64_t num, blk;
> +			num = fs->inode_blocks_per_group;
> +			blk = new_blk;
> +			while (num) {
> +				int gr = ext2fs_group_of_blk2(fs, blk);
> +				last_blk = ext2fs_group_last_block2(fs, gr);
> +				blk64_t n = num;
> +
> +				if (blk + num > last_blk)
> +					n = last_blk - blk + 1;
> +
> +				ext2fs_bg_free_blocks_count_set(fs, gr,
> +					ext2fs_bg_free_blocks_count(fs, gr) -
> +					n/EXT2FS_CLUSTER_RATIO(fs));
> +				ext2fs_bg_flags_clear(fs, gr,
> +					EXT2_BG_BLOCK_UNINIT);
> +				ext2fs_group_desc_csum_set(fs, gr);
> +				ext2fs_free_blocks_count_add(fs->super, -n);
> +				blk += n;
> +				num -= n;
> +			}
> +		}
>  		ext2fs_inode_table_loc_set(fs, group, new_blk);
>  	}
>  	ext2fs_group_desc_csum_set(fs, group);
> -- 
> 2.7.5
>