[Devel] [PATCH RH7 0/4] Port open_tree and move_mount syscalls

[Pavel Tikhomirov]

These syscalls were added as preparation step for new mount api (fsopen,
fsconfig, fsmount and fspick will be ported separately).

We can use them to implement "cross-namespace bind-mounting" like this:

fd = open_tree(AT_FDCWD, "/mnt", OPEN_TREE_CLONE);
setns(nsfd, CLONE_NEWNS);
move_mount(fd, "", AT_FDCWD, "/mnt2", MOVE_MOUNT_F_EMPTY_PATH);

This will allow us implementing feature of adding bindmounts to runing
container instead of having unreliable external propagations.

It is needed to VZ8, but does not apply cleanly so I will send it
separately.

https://jira.sw.ru/browse/PSBM-107263
    
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

Al Viro (2):
  saner handling of temporary namespaces
  vfs: syscall: Add open_tree(2) to reference or clone a mount

David Howells (2):
  vfs: syscall: Add move_mount(2) to move mounts around
  teach move_mount(2) to work with OPEN_TREE_CLONE

 arch/x86/syscalls/syscall_32.tbl |   3 +
 arch/x86/syscalls/syscall_64.tbl |   3 +
 fs/file_table.c                  |   9 +-
 fs/internal.h                    |   1 +
 fs/mount.h                       |   5 +
 fs/namespace.c                   | 421 ++++++++++++++++++++++++-------
 include/linux/fs.h               |   3 +
 include/linux/security.h         |  12 +
 include/linux/syscalls.h         |   5 +
 include/uapi/linux/fcntl.h       |   1 +
 include/uapi/linux/fs.h          |  17 ++
 security/capability.c            |   6 +
 security/security.c              |   5 +
 security/selinux/hooks.c         |   9 +
 14 files changed, 399 insertions(+), 101 deletions(-)

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2.24.1