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From: Miklos Szeredi <miklos@szeredi.hu>
Date: Fri, 28 Oct 2016 16:25:28 +0200
Message-ID: <CAJfpegtfa5fBozu7GFFtB+eEHKxdmsg6byysVcLGiWuXHtfL2w@mail.gmail.com>
Subject: Re: [PATCH] vfs: fix vfs_clone_file_range() for overlayfs files
To: Amir Goldstein <amir73il@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>, Christoph Hellwig <hch@lst.de>,
        "linux-unionfs@vger.kernel.org" <linux-unionfs@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org
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On Wed, Oct 26, 2016 at 9:34 PM, Amir Goldstein <amir73il@gmail.com> wrote:
> With overlayfs, it is wrong to compare file_inode(inode)->i_sb
> of regular files with those of non-regular files, because the
> former reference the real (upper/lower) sb and the latter reference
> the overlayfs sb.
>
> Move the test for same super block after the sanity tests for
> clone range of directory and non-regular file.

Better:  compare ->f_path.dentry->d_sb instead of file_inode()->i_sb.
We don't want to be mixing files that come from overlayfs and ones
that come from the underlying layers.

BTW, would it be worthwhile adding clone_file_range() support to overlayfs?

Thanks,
Miklos