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From:   David Howells <dhowells@redhat.com>
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To:     "Theodore Y. Ts'o" <tytso@mit.edu>
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Subject: Re: BUG: Mount ignores mount options
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Date:   Fri, 10 Aug 2018 16:53:58 +0100
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Theodore Y. Ts'o <tytso@mit.edu> wrote:

> Even *with* file system support, there's no way today for the VFS to
> keep track of whether a pathname resolution came through one
> mountpoint or another, so I can't do something like this:

Ummm...  Isn't that encoded in the vfsmount pointer in struct path?

However, the case folding stuff - is that a superblockism of a mountpointism?

> So if the file system has been mounted with one set of mount options,
> and you want to try to mount it with a conflicting set of mount
> options and you don't want it to silently ignore the mount options,
> the *only* thing we can today is to refuse the mount and return an
> error.  

With fsopen() there is the option to have the filesystem and the LSM attempt
to compare the non-key[*] mount options and reject the attempt to share if
they differ in any way.

David


[*] sget lookup keys, that is.