[Devel] [PATCH rh7 0/6] Rework devtmpfs virtualization

[Vladimir Davydov]

Currently, we implement full-featured devtmpfs virtualization for VE:
when a deivice is created in a VE "namespace", we send a signal to
kdevtmpfs to create the devnode on devtmpfs mount corresponding to the
VE. This seems to be over-complicated: all this work can be done from
userspace, because we only have a hardcoded list of devices created
exclusively for VE on container start. Those are tty-related stuff and
mem devices, and we only need the latter to create devtmpfs nodes.
Moreover, it is buggy: ve_stop_ns, which destroys VE devtmpfs mount can
be called before a VE tty device is unregistered, resulting in a KP:

https://jira.sw.ru/browse/PSBM-35077

This patch therefore simplifies it. It makes the kernel only provide a
single empty tmpfs mount per VE, which appears on an attempt to mount
devtmpfs from inside a VE. The content of the fs is to be filled by the
userspace on container start, which will be done in the scope of

https://jira.sw.ru/browse/PSBM-35146

Vladimir Davydov (6):
  Revert "ve/devtmpfs: Create required devices on container startup"
  Revert "ve/devtmpfs: pass proper options string"
  Revert "devtmpfs: containerize it with new obj ns operation"
  Revert "fs: add data pointer to mount_ns()"
  Revert "devtmpfs: per-VE mounts introduced"
  devtmpfs: lightweight virtualization

 drivers/base/devtmpfs.c    | 127 +++++++++++++++++++++++----------------------
 drivers/char/mem.c         |  20 -------
 fs/binfmt_misc.c           |   2 +-
 fs/nfsd/nfsctl.c           |   2 +-
 fs/super.c                 |   4 +-
 fs/sysfs/ve.c              |   9 ----
 include/linux/device.h     |   4 --
 include/linux/fs.h         |   2 +-
 include/linux/kobject_ns.h |   2 -
 include/linux/ve.h         |   4 +-
 ipc/mqueue.c               |   2 +-
 kernel/ve/ve.c             |  68 ++----------------------
 net/sunrpc/rpc_pipe.c      |   2 +-
 13 files changed, 78 insertions(+), 170 deletions(-)

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2.1.4