Re: [PATCH 1/3] xfs: introduce XFS_MAX_FILEOFF

[Dave Chinner <david@fromorbit.com>]

On Tue, Jan 07, 2020 at 08:17:38PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Introduce a new #define for the maximum supported file block offset.
> We'll use this in the next patch to make it more obvious that we're
> doing some operation for all possible inode fork mappings after a given
> offset.  We can't use ULLONG_MAX here because bunmapi uses that to
> detect when it's done.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_format.h |    1 +
>  fs/xfs/xfs_reflink.c       |    3 ++-
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index 1b7dcbae051c..c2976e441d43 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -1540,6 +1540,7 @@ typedef struct xfs_bmdr_block {
>  #define BMBT_BLOCKCOUNT_BITLEN	21
>  
>  #define BMBT_STARTOFF_MASK	((1ULL << BMBT_STARTOFF_BITLEN) - 1)
> +#define XFS_MAX_FILEOFF		(BMBT_STARTOFF_MASK)

Isn't the maximum file offset in the BMBT the max start offset + the
max length of the extent that is located at BMBT_STARTOFF_MASK?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com