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From:   David Howells <dhowells@redhat.com>
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To:     Jann Horn <jannh@google.com>
Cc:     dhowells@redhat.com, Al Viro <viro@zeniv.linux.org.uk>,
        raven@themaw.net, linux-fsdevel <linux-fsdevel@vger.kernel.org>,
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Subject: Re: [PATCH 3/7] vfs: Add a mount-notification facility
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Date:   Wed, 29 May 2019 12:16:27 +0100
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Jann Horn <jannh@google.com> wrote:

> I don't really know. I guess it depends on how it's being used? If
> someone decides to e.g. make a file browser that installs watches for
> a bunch of mountpoints for some fancy sidebar showing the device
> mounts on the system, or something like that, that probably shouldn't
> inhibit unmounting... I don't know if that's a realistic use case.

In such a use case, I would envision the browser putting a watch on "/".  A
watch sees all events in the subtree rooted at that point and you must apply a
filter that filters them out if you're not interested (filter on
WATCH_INFO_IN_SUBTREE using info_filter and info_mask).

David