Re: More questions on unionmount

[David Howells <dhowells@redhat.com>]

Hmmm...

| /**
|  * clone_union_tree - Clone all union-able mounts at this mountpoint
|  * @topmost: vfsmount of topmost layer
|  * @mntpnt: target of union mount
|  *
|  * Given the target mountpoint of a union mount, clone all the mounts at that
|  * mountpoint (well, pathname) that qualify as a union lower layer. ...

Is this so that the unionmount can survive MS_BIND and MS_MOVE?

|  * Returns error if any of the mounts or submounts mounted on or below this
|  * pathname are unsuitable for union mounting.  This means you can't construct
|  * a union mount at the root of an existing mount without unioning it.

If I understand this correctly, I'd rephrase this to be:

 * Returns an error if any of the stack of mounts or submounts currently
 * mounted on @mntpnt are unsuitable for union mounting.  This means you cannot
 * construct a union mount over the root of an existing mount without including
 * it in the union or having it prevent the union.

David