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From: David Howells <dhowells@redhat.com>
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To: ebiederm@xmission.com (Eric W. Biederman)
Cc: dhowells@redhat.com,
        Alan Jenkins <alan.christopher.jenkins@gmail.com>,
        Al Viro <viro@ZenIV.linux.org.uk>, linux-api@vger.kernel.org,
        torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, mszeredi@redhat.com
Subject: Re: [PATCH 31/34] vfs: syscall: Add fspick() to select a superblock for reconfiguration [ver #12]
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Date: Wed, 17 Oct 2018 16:24:23 +0100
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Eric W. Biederman <ebiederm@xmission.com> wrote:

> Davids check will work for bind mounts as well.  It just won't work it
> just won't work for files or subdirectories of some mountpoint.

Bind mounts have to be done with open_tree() and move_mount().  You can't now
do fsmount() on something fspick()'d.

David