On Fri, Jul 08, 2016 at 01:38:19PM -0700, Andrew Vagin wrote:
What do you think about the idea to mount nsfs and be able to look up
any alive namespace by inum:
$ tree .
.
├── mnt{inum}
│ └── user -> ../user{inum}
├── pid{inum}
│ ├── pid{inum}
│ │ └── user -> ../../user{inum}/user{inum}
│ └── user -> ../user{inum}
└── user{inum}
└── user{inum}
https://lkml.org/lkml/2016/7/8/59
I think it solves all requirements which were mentioned in this thread.
It may need an additional entry per directory for the bit you setns.
Maybe ‘handle’?
$ tree .
.
├── mnt{inum}
│ ├── handle -> mnt:[{inum}]
│ └── user -> ../user{inum}
…
but that's not a major revision.
On Fri, Jul 08, 2016 at 07:35:33AM -0700, James Bottomley wrote:
quoted
On Fri, 2016-07-08 at 02:44 -0500, Eric W. Biederman wrote:
quoted
Starting with 4.8 we are also going to need to be able to
retrieve the user namespace owner of filesystems. That will be
an interesting mix.
This is per mount point, isn't it? so it can't be in /proc/fs/ and
it would have to be per local mount tree. Yes, that is a bit
nasty. Sounds like we might need to unfold mount or mountinfo
into something that has one directory per entry?
If we will be able to look up namespaces in nsfs by inum, we can
print an userns inum in mountinfo.
With the tree view you can find a namespace by inum (if it's one of
your descendants), but it's not going to be particularly efficient
(you'll have to walk the tree). Folks that need to do that quickly
can index the tree (which would be fairly straightforward if the nsfs
mount supports inotify), but it would be nice to have a more elegant
solution for this use-case.
Cheers,
Trevor
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