Re: [PATCH] Add dax mount option to man xfs(5)

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Mar 15, 2021 at 04:02:50PM +0100, Carlos Maiolino wrote:
> Details are already in kernel's documentation, but make dax mount option
> information accessible through xfs(5) manpage.
> 
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---
>  man/man5/xfs.5 | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/man/man5/xfs.5 b/man/man5/xfs.5
> index 7642662f..46b0558a 100644
> --- a/man/man5/xfs.5
> +++ b/man/man5/xfs.5
> @@ -133,6 +133,24 @@ by the filesystem.
>  CRC enabled filesystems always use the attr2 format, and so
>  will reject the noattr2 mount option if it is set.
>  .TP
> +.BR dax=value
> +Set DAX behavior for the current filesystem. This mount option accepts the

It might be worth defining what DAX (the acronym) is...

"Set CPU direct access (DAX) behavior for regular files in the
filesystem."

> +following values:
> +
> +"dax=inode" DAX will be enabled only on files with FS_XFLAG_DAX applied.

"...enabled on regular files..."

> +
> +"dax=never" DAX will be disabled by the whole filesystem including files with
> +FS_XFLAG_DAX applied"

"DAX will not be enabled for any files.  FS_XFLAG_DAX will be ignored."

> +
> +"dax=always" DAX will be enabled to every file in the filesystem inclduing files

"DAX will be enabled for all regular files, regardless of the
FS_XFLAG_DAX state."

> +without FS_XFLAG_DAX applied"
> +
> +If no option is used when mounting a pmem device, dax=inode will be used as

"If no option is used when mounting a filesystem stored on a device
capable of DAX access modes, dax=inode...."

(DAX is a possibility with more than just persistent memory now...)

--D

> +default.
> +
> +For details regarding DAX behavior in kernel, please refer to kernel's
> +documentation at filesystems/dax.txt
> +.TP
>  .BR discard | nodiscard
>  Enable/disable the issuing of commands to let the block
>  device reclaim space freed by the filesystem.  This is
> -- 
> 2.29.2
>