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Date:   Sun, 11 Jun 2023 21:36:23 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Amir Goldstein <amir73il@gmail.com>
Cc:     Miklos Szeredi <miklos@szeredi.hu>,
        Christian Brauner <brauner@kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
        linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org
Subject: Re: [PATCH v2 2/3] fs: introduce f_real_path() helper
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On Sun, Jun 11, 2023 at 04:27:31PM +0300, Amir Goldstein wrote:
> Overlayfs knows the real path of underlying dentries.  Add an optional
> struct vfsmount out argument to ->d_real(), so callers could compose the
> real path.
> 
> Add a helper f_real_path() that uses this new interface to return the
> real path of f_inode, for overlayfs internal files whose f_path if a
> "fake" overlayfs path and f_inode is the underlying real inode.

I really don't like this ->d_real nagic.  Most callers of it
really can't ever be on overlayfs.  So I'd suggest we do an audit
of the callers of file_dentry and drop all the pointless ones
first, and improve the documentation on when to use it.