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Date:   Tue, 2 Jun 2020 11:14:44 -0700 (PDT)
From:   "Darrick J. Wong" <darrick.wong@oracle.com>
To:     Xiao Yang <yangx.jy@cn.fujitsu.com>
Cc:     ira.weiny@intel.com, fstests@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Chinner <david@fromorbit.com>,
        Christoph Hellwig <hch@lst.de>,
        "Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
        Jeff Moyer <jmoyer@redhat.com>, linux-ext4@vger.kernel.org,
        linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] xfs/XXX: Add xfs/XXX
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 <20200413163025.GB6742@magnolia> <5ED61324.6010300@cn.fujitsu.com>
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On Tue, Jun 02, 2020 at 04:51:48PM +0800, Xiao Yang wrote:
> On 2020/4/14 0:30, Darrick J. Wong wrote:
> > This might be a good time to introduce a few new helpers:
> > 
> > _require_scratch_dax ("Does $SCRATCH_DEV support DAX?")
> > _require_scratch_dax_mountopt ("Does the fs support the DAX mount options?")
> > _require_scratch_daX_iflag ("Does the fs support FS_XFLAG_DAX?")
> Hi Darrick,
> 
> Now, I am trying to introduce these new helpers and have some questions:
> 1) There are five testcases related to old dax implementation, should we
> only convert them to new dax implementation or make them compatible with old
> and new dax implementation?

What is the 'old' DAX implementation?  ext2 XIP?

> 2) I think _require_xfs_io_command "chattr" "x" is enough to check if fs
> supports FS_XFLAG_DAX.  Is it necessary to add _require_scratch_dax_iflag()?
> like this:
> _require_scratch_dax_iflag()
> {
> 	_require_xfs_io_command "chattr" "x"
> }

I suggested that list based on the major control knobs that will be
visible to userspace programs.  Even if this is just a one-line helper,
its name is useful for recognizing which of those knobs we're looking
for.

Yes, you could probably save a trivial amount of time by skipping one
iteration of bash function calling, but now everyone has to remember
that the xfs_io chattr "x" flag means the dax inode flag, and not
confuse it for chmod +x or something else.

--D

> Best Regards,
> Xiao Yang
> 
>