Re: [PATCH V6 5/8] fs/xfs: Create function xfs_inode_enable_dax()

Dave Chinner
2020-04-08T00:05:39Z

On Tue, Apr 07, 2020 at 11:29:55AM -0700, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> xfs_inode_supports_dax() should reflect if the inode can support DAX not
> that it is enabled for DAX.
>
> Change the use of xfs_inode_supports_dax() to reflect only if the inode
> and underlying storage support dax.
>
> Add a new function xfs_inode_enable_dax() which reflects if the inode
> should be enabled for DAX.
>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
....
>
> +STATIC bool
> +xfs_inode_enable_dax(
> + struct xfs_inode *ip)
> +{
> + u32 dax_mode = xfs_mount_dax_mode(ip->i_mount);
> +
> + if (dax_mode == XFS_DAX_NEVER || !xfs_inode_supports_dax(ip))
> + return false;
> + if (dax_mode == XFS_DAX_ALWAYS || ip->i_d.di_flags2 & XFS_DIFLAG2_DAX)
> + return true;

These compound || statements are better written as single conditions
as they are all sequential logic checks and we can't skip over
checks.

if (mp->m_flags & XFS_MOUNT_DAX_NEVER)
return false;
if (!xfs_inode_supports_dax(ip))
return false;
if (mp->m_flags & XFS_MOUNT_DAX_ALWAYS)
return true;
if (ip->i_d.di_flags2 & XFS_DIFLAG2_DAX)
return true;
return false;

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com