Re: [PATCH 2/6] mkfs: check root inode location

[Brian Foster <bfoster@redhat.com>]

On Wed, Dec 04, 2019 at 09:04:35AM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Make sure the root inode gets created where repair thinks it should be
> created.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  libxfs/libxfs_api_defs.h |    1 +
>  mkfs/xfs_mkfs.c          |   39 +++++++++++++++++++++++++++++++++------
>  2 files changed, 34 insertions(+), 6 deletions(-)
> 
> 
> diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
> index 645c9b1b..f8e7d82d 100644
> --- a/libxfs/libxfs_api_defs.h
> +++ b/libxfs/libxfs_api_defs.h
> @@ -156,5 +156,6 @@
>  
>  #define xfs_ag_init_headers		libxfs_ag_init_headers
>  #define xfs_buf_delwri_submit		libxfs_buf_delwri_submit
> +#define xfs_ialloc_calc_rootino		libxfs_ialloc_calc_rootino
>  
>  #endif /* __LIBXFS_API_DEFS_H__ */
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index 18338a61..71be033d 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -3521,6 +3521,38 @@ rewrite_secondary_superblocks(
>  	libxfs_writebuf(buf, LIBXFS_EXIT_ON_FAILURE);
>  }
>  
> +static void
> +check_root_ino(
> +	struct xfs_mount	*mp)
> +{
> +	xfs_ino_t		ino;
> +
> +	if (XFS_INO_TO_AGNO(mp, mp->m_sb.sb_rootino) != 0) {
> +		fprintf(stderr,
> +			_("%s: root inode created in AG %u, not AG 0\n"),
> +			progname, XFS_INO_TO_AGNO(mp, mp->m_sb.sb_rootino));
> +		exit(1);
> +	}
> +
> +	/*
> +	 * The superblock points to the root directory inode, but xfs_repair
> +	 * expects to find the root inode in a very specific location computed
> +	 * from the filesystem geometry for an extra level of verification.
> +	 *
> +	 * Fail the format immediately if those assumptions ever break, because
> +	 * repair will toss the root directory.
> +	 */
> +	ino = libxfs_ialloc_calc_rootino(mp, -1);
> +	if (mp->m_sb.sb_rootino != ino) {
> +		fprintf(stderr,
> +	_("%s: root inode (%llu) not allocated in expected location (%llu)\n"),
> +			progname,
> +			(unsigned long long)mp->m_sb.sb_rootino,
> +			(unsigned long long)ino);
> +		exit(1);
> +	}
> +}
> +
>  int
>  main(
>  	int			argc,
> @@ -3807,12 +3839,7 @@ main(
>  	/*
>  	 * Protect ourselves against possible stupidity
>  	 */
> -	if (XFS_INO_TO_AGNO(mp, mp->m_sb.sb_rootino) != 0) {
> -		fprintf(stderr,
> -			_("%s: root inode created in AG %u, not AG 0\n"),
> -			progname, XFS_INO_TO_AGNO(mp, mp->m_sb.sb_rootino));
> -		exit(1);
> -	}
> +	check_root_ino(mp);
>  
>  	/*
>  	 * Re-write multiple secondary superblocks with rootinode field set
>