Re: [PATCH V5 05/12] fs/xfs: Create function xfs_inode_enable_dax()

Dave Chinner
2020-03-01T22:37:53Z

On Wed, Feb 26, 2020 at 09:24:35PM -0800, 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>
>
> ---
> Changes from v3:
> Update functions and names to be more clear
> Update commit message
> Merge with
> 'fs/xfs: Clean up DAX support check'
> don't allow IS_DAX() on a directory
> use STATIC macro for static
> make xfs_inode_supports_dax() static
> ---
> fs/xfs/xfs_iops.c | 25 +++++++++++++++++++------
> 1 file changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 81f2f93caec0..ff711efc5247 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -1237,19 +1237,18 @@ static const struct inode_operations xfs_inline_symlink_inode_operations = {
> };
>
> /* Figure out if this file actually supports DAX. */
> -static bool
> +STATIC bool
> xfs_inode_supports_dax(
> struct xfs_inode *ip)
> {
> struct xfs_mount *mp = ip->i_mount;
>
> /* Only supported on non-reflinked files. */
> - if (!S_ISREG(VFS_I(ip)->i_mode) || xfs_is_reflink_inode(ip))
> + if (xfs_is_reflink_inode(ip))
> return false;
>
> - /* DAX mount option or DAX iflag must be set. */
> - if (!(mp->m_flags & XFS_MOUNT_DAX) &&
> - !(ip->i_d.di_flags2 & XFS_DIFLAG2_DAX))
> + /* Only supported on regular files. */
> + if (!S_ISREG(VFS_I(ip)->i_mode))
> return false;

Why split the initial check? The "non-reflinked files" comment is
pretty explicit, so splitting it just to add a "only support on
regular files" comment doesn't actually add any value here.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com