This series implements the mkdirat_fd() syscall that was suggested over
at the UAPI group kernel feature page [1] with some tests.

Obviously, if we want this we should also implement mknodeat_fd() and
symlinkat_fd(), but their implementation can be done quite similar I
believe.

I have added an unigned int flags like [2] suggests and an example flag
that we may want to remove (it right now mainly serves an internal
purpose). But it marks where I would want to place the definitions.

This has been compiled and tested on x86 only. [2] is a bit confusing
here and there, so I hope I have added the proper syscall definitions
everywhere where they needs to be added.

[1]: https://github.com/uapi-group/kernel-features?tab=readme-ov-file#race-free-creation-and-opening-of-non-file-inodes
[2]: https://www.kernel.org/doc/html/latest/process/adding-syscalls.html

Jori Koolstra (2):
  vfs: syscalls: add mkdirat_fd()
  selftest: add tests for mkdirat_fd()

 arch/x86/entry/syscalls/syscall_64.tbl        |   1 +
 fs/internal.h                                 |   1 +
 fs/namei.c                                    |  26 +++-
 include/linux/fcntl.h                         |   2 +
 include/linux/syscalls.h                      |   2 +
 include/uapi/asm-generic/fcntl.h              |   3 +
 include/uapi/asm-generic/unistd.h             |   5 +-
 scripts/syscall.tbl                           |   1 +
 tools/include/uapi/asm-generic/unistd.h       |   5 +-
 tools/testing/selftests/filesystems/Makefile  |   4 +-
 .../selftests/filesystems/mkdirat_fd_test.c   | 139 ++++++++++++++++++
 11 files changed, 183 insertions(+), 6 deletions(-)
 create mode 100644 tools/testing/selftests/filesystems/mkdirat_fd_test.c

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2.53.0