On Fri, Sep 27, 2013 at 05:14:04PM -0700, Darrick J. Wong wrote:
> Perform a quick sanity check of bitmap and inode table block numbers when
> loading them, and if there's something suspicious, mark the block group
> corrupt.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
One comment below. Otherwise the patch looks good to me.
Reviewed-by: Zheng Liu <wenqing.lz@xxxxxxxxxx>
> ---
> fs/ext4/balloc.c | 7 +++++++
> fs/ext4/ext4.h | 2 ++
> fs/ext4/ialloc.c | 6 ++++++
> fs/ext4/inode.c | 9 +++++++++
> fs/ext4/super.c | 21 +++++++++++++++++++++
> 5 files changed, 45 insertions(+)
[...]
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 2c2e6cb..d22248e 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2049,6 +2049,27 @@ void ext4_group_desc_csum_set(struct super_block *sb, __u32 block_group,
> gdp->bg_checksum = ext4_group_desc_csum(EXT4_SB(sb), block_group, gdp);
> }
>
> +/* returns 1 if the location of a blockgroup data item seems sane */
> +int ext4_is_sane_bgdata_location(struct super_block *sb, ext4_group_t grp,
> + ext4_fsblk_t blk)
> +{
> + struct ext4_sb_info *sbi = EXT4_SB(sb);
> + ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
> + ext4_fsblk_t last_block;
> +
> + if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
> + last_block = ext4_blocks_count(sbi->s_es) - 1;
> + else {
> + first_block += grp * sbi->s_blocks_per_group;
> + last_block = first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
> + }
> +
> + if (last_block >= ext4_blocks_count(sbi->s_es))
> + last_block = ext4_blocks_count(sbi->s_es) - 1;
> +
> + return blk >= first_block && blk <= last_block;
> +}
> +
> /* Called at mount-time, super-block is locked */
> static int ext4_check_descriptors(struct super_block *sb,
> ext4_group_t *first_not_zeroed)
FWIW, I notice that in ext4_check_descriptors() we also check the
location of bitmap. So maybe we could use ext4_is_sane_bgdata_location
in that function.
- Zheng
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