[PATCH] xfs: check sizes of XFS on-disk structures at compile time

[Darrick J. Wong]

On Mon, Jan 11, 2016 at 03:26:57PM -0800, Darrick J. Wong wrote:
> Check the sizes of XFS on-disk structures when compiling the kernel.
> Use this to catch inadvertent changes in structure size due to padding
> and alignment issues, etc.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
> ---
>  fs/xfs/libxfs/xfs_format.h |    4 ++++
>  fs/xfs/xfs_super.c         |   45 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 49 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index e2536bb..a589b47 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -1509,4 +1509,8 @@ struct xfs_acl {
>  #define SGI_ACL_FILE_SIZE	(sizeof(SGI_ACL_FILE)-1)
>  #define SGI_ACL_DEFAULT_SIZE	(sizeof(SGI_ACL_DEFAULT)-1)
>  
> +#define XFS_CHECK_STRUCT_SIZE(structname, size) \
> +	BUILD_BUG_ON_MSG(sizeof(structname) != (size), "XFS: sizeof(struct " \
> +		#structname ") is wrong, expected " #size)
> +

Since xfs/122 will handle this on the userspace side, this can move to
xfs_super.c.

>  #endif /* __XFS_FORMAT_H__ */
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 36bd882..31b69d1 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1812,11 +1812,56 @@ xfs_destroy_workqueues(void)
>  	destroy_workqueue(xfs_alloc_wq);
>  }
>  
> +static void __init
> +xfs_check_ondisk_structs(void)
> +{
> +	/* on-disk structures */
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_dsb,			264);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_agf,			224);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_agi,			336);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_agfl,			36);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_timestamp,		8);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_dinode,		176);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_disk_dquot,		104);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_dqblk,			136);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_dsymlink_hdr,		56);
> +	XFS_CHECK_STRUCT_SIZE(xfs_alloc_rec_t,			8);
> +	XFS_CHECK_STRUCT_SIZE(xfs_alloc_key_t,			8);
> +	XFS_CHECK_STRUCT_SIZE(xfs_alloc_ptr_t,			4);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_inobt_rec,		16);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_inobt_key,		4);
> +	XFS_CHECK_STRUCT_SIZE(xfs_inobt_ptr_t,			4);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_bmdr_block,		4);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_bmbt_rec,		16);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_bmbt_key,		8);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_btree_block,		72);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_acl_entry,		12);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_acl,			4);

Forgot the dir/attr structures here.

> +	/* log structures */
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_trans_header,		16);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_inode_log_format_32,	52);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_inode_log_format_64,	56);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_ictimestamp,		8);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_icdinode,		176);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_extent_32,		12);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_extent_64,		16);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_32,	28);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_64,	32);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_32,	28);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_64,	32);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_dq_logformat,		24);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_qoff_logformat,	20);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_icreate_log,		28);
> +}

Perhaps this huge function ought to hide away in its own file?

--D

> +
>  STATIC int __init
>  init_xfs_fs(void)
>  {
>  	int			error;
>  
> +	xfs_check_ondisk_structs();
> +
>  	printk(KERN_INFO XFS_VERSION_STRING " with "
>  			 XFS_BUILD_OPTIONS " enabled\n");
>  
> 
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