linux-kernel - Re: [PATCH V6 5/8] fs/xfs: Create function xfs_inode_enable

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Message-ID: <20200408001332.GB569068@iweiny-DESK2.sc.intel.com>
Date:   Tue, 7 Apr 2020 17:13:33 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Dave Chinner <david@...morbit.com>
Cc:     linux-kernel@...r.kernel.org,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Christoph Hellwig <hch@....de>,
        "Theodore Y. Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>,
        Jeff Moyer <jmoyer@...hat.com>, linux-ext4@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH V6 5/8] fs/xfs: Create function xfs_inode_enable_dax()

On Wed, Apr 08, 2020 at 10:05:33AM +1000, Dave Chinner wrote:
> On Tue, Apr 07, 2020 at 11:29:55AM -0700, ira.weiny@...el.com wrote:
> > From: Ira Weiny <ira.weiny@...el.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@...el.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;

Updated for V7

Thanks,
Ira

> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@...morbit.com