Assign a unique proc inode to each namespace, and use that
inode number to ensure we only allocate at most one proc
inode for every namespace in proc.
A single proc inode per namespace allows userspace to test
to see if two processes are in the same namespace.
This has been a long requested feature and only blocked because
a naive implementation would put the id in a global space and
would ultimately require having a namespace for the names of
namespaces, making migration and certain virtualization tricks
impossible.
We still don't have per superblock inode numbers for proc, which
appears necessary for application unaware checkpoint/restart and
migrations (if the application is using namespace file descriptors)
but that is now allowd by the design if it becomes important.
I have preallocated the ipc and uts initial proc inode numbers so
their structures can be statically initialized.
Change-Id: I01d42c2f051fd74b1474d9d8378ccc78174cf3cf
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Git-commit: f80cd4676998eb352d1a8b9df0f3663537a9ce93
Git-repo: https://android.googlesource.com/kernel/common/
[schikk@codeaurora.org: Resolved merge conflicts ]
CRs-Fixed: 901628
Signed-off-by: Swetha Chikkaboraiah <schikk@codeaurora.org>
Eric W. Biederman
80f4b770f4