Re: [PATCH v2 5/8] fs: lockless mntns lookup for nsfs

[Christian Brauner <brauner@kernel.org>]

> > This only works if the entries are inserted in order -- if not, you can
> > do something like:
> 
> If I understand your concern correctly then the entries should always be
> inserted in order. Mount namespaces are sequentially allocated
> serialized on the namespace semaphore "namespace_sem. So each mount
> namespace receives a unique 64bit sequence number. If ten mount
> namespaces are created with 1, 2, 3, ..., 10 then they are inserted into
> the rbtree in that order. And so they should be added to that list in
> the same order. That's why I kept it that simple.

Nope, you were right, I was wrong. We allocate the sequence number
before we hold the namespace semaphore. I misremembered that code.
I'll fix this up as you suggested. Thanks!