Re: [PATCH v2] xfs: don't set v3 xflags for v2 inodes

[Brian Foster <bfoster@redhat.com>]

On Wed, Aug 30, 2017 at 09:38:25AM -0700, Darrick J. Wong wrote:
> Reject attempts to set XFLAGS that correspond to di_flags2 inode flags
> if the inode isn't a v3 inode, because di_flags2 only exists on v3.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

That lazy reflink flag clear still seems hacky. That aside, this looks
fine to me:

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

>  fs/xfs/xfs_ioctl.c |   37 +++++++++++++++++++++++++++++--------
>  1 file changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 06ca244..82d14fe 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1016,32 +1016,37 @@ xfs_diflags_to_linux(
>  #endif
>  }
>  
> +#define XFS_V3_INODE_XFLAGS	(FS_XFLAG_DAX | \
> +				 FS_XFLAG_COWEXTSIZE)
>  static int
> -xfs_ioctl_setattr_xflags(
> -	struct xfs_trans	*tp,
> +xfs_check_diflags(
>  	struct xfs_inode	*ip,
> -	struct fsxattr		*fa)
> +	__u32			xflags)
>  {
>  	struct xfs_mount	*mp = ip->i_mount;
>  
> +	/* Can't set flags2 fields on a v2 inode. */
> +	if (ip->i_d.di_version < 3 && (xflags & XFS_V3_INODE_XFLAGS))
> +		return -EINVAL;
> +
>  	/* Can't change realtime flag if any extents are allocated. */
>  	if ((ip->i_d.di_nextents || ip->i_delayed_blks) &&
> -	    XFS_IS_REALTIME_INODE(ip) != (fa->fsx_xflags & FS_XFLAG_REALTIME))
> +	    XFS_IS_REALTIME_INODE(ip) != (xflags & FS_XFLAG_REALTIME))
>  		return -EINVAL;
>  
>  	/* If realtime flag is set then must have realtime device */
> -	if (fa->fsx_xflags & FS_XFLAG_REALTIME) {
> +	if (xflags & FS_XFLAG_REALTIME) {
>  		if (mp->m_sb.sb_rblocks == 0 || mp->m_sb.sb_rextsize == 0 ||
>  		    (ip->i_d.di_extsize % mp->m_sb.sb_rextsize))
>  			return -EINVAL;
>  	}
>  
>  	/* Clear reflink if we are actually able to set the rt flag. */
> -	if ((fa->fsx_xflags & FS_XFLAG_REALTIME) && xfs_is_reflink_inode(ip))
> +	if ((xflags & FS_XFLAG_REALTIME) && xfs_is_reflink_inode(ip))
>  		ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
>  
>  	/* Don't allow us to set DAX mode for a reflinked file for now. */
> -	if ((fa->fsx_xflags & FS_XFLAG_DAX) && xfs_is_reflink_inode(ip))
> +	if ((xflags & FS_XFLAG_DAX) && xfs_is_reflink_inode(ip))
>  		return -EINVAL;
>  
>  	/*
> @@ -1049,10 +1054,26 @@ xfs_ioctl_setattr_xflags(
>  	 * we have appropriate permission.
>  	 */
>  	if (((ip->i_d.di_flags & (XFS_DIFLAG_IMMUTABLE | XFS_DIFLAG_APPEND)) ||
> -	     (fa->fsx_xflags & (FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND))) &&
> +	     (xflags & (FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND))) &&
>  	    !capable(CAP_LINUX_IMMUTABLE))
>  		return -EPERM;
>  
> +	return 0;
> +}
> +
> +static int
> +xfs_ioctl_setattr_xflags(
> +	struct xfs_trans	*tp,
> +	struct xfs_inode	*ip,
> +	struct fsxattr		*fa)
> +{
> +	struct xfs_mount	*mp = ip->i_mount;
> +	int			ret;
> +
> +	ret = xfs_check_diflags(ip, fa->fsx_xflags);
> +	if (ret)
> +		return ret;
> +
>  	xfs_set_diflags(ip, fa->fsx_xflags);
>  	xfs_diflags_to_linux(ip);
>  	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
> --
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