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Date:   Thu, 11 Jun 2020 03:17:10 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Mike Kravetz <mike.kravetz@oracle.com>,
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Subject: Re: [PATCH v2] ovl: provide real_file() and overlayfs
 get_unmapped_area()
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On Wed, Jun 10, 2020 at 06:36:16PM -0700, Matthew Wilcox wrote:

> 	while (file->f_mode & FMODE_OVL_UPPER)
> 		file = file->private_data;
> 	return file;
> 
> Or are you proposing that overlayfs copy FMODE_HUGEPAGES from the
> underlying fs to the overlaying fs?

The latter - that way nobody outside of overlayfs needs to know what
its ->private_data points to, for one thing.  And it's cheaper that
way, obviously.