Changes in v2:
- rename ENOTREGULAR to ENOTREG
- define ENOTREG in uapi/asm-generic/errno.h (instead of errno-base.h) and in arch/*/include/uapi/asm/errno.h files
- override O_REGULAR in arch/{alpha,sparc,parisc}/include/uapi/asm/fcntl.h due to clash with include/uapi/asm-generic/fcntl.h
- I have kept the kselftest but now that O_REGULAR and ENOTREG can have different value on different architectures I am not sure if it's right
- v1 is at: https://lore.kernel.org/linux-fsdevel/20260125141518.59493-1-dorjoychy111@gmail.com/T/

Hi,

I came upon this "Ability to only open regular files" uapi feature suggestion
from https://uapi-group.org/kernel-features/#ability-to-only-open-regular-files
and thought it would be something I could do as a first patch and get to
know the kernel code a bit better.

I am not quite sure if the semantics that I baked into the code for this
O_REGULAR flag's behavior when combined with other flags like O_CREAT look
good and if there are other places that need the checks. I can fixup my
patch according to suggestions for improvement. I did some happy path testing
and the O_REGULAR flag seems to work as intended.

Thanks.

Regards,
Dorjoy

Dorjoy Chowdhury (2):
  open: new O_REGULAR flag support
  kselftest/openat2: test for O_REGULAR flag

 arch/alpha/include/uapi/asm/errno.h           |  2 +
 arch/alpha/include/uapi/asm/fcntl.h           |  1 +
 arch/mips/include/uapi/asm/errno.h            |  2 +
 arch/parisc/include/uapi/asm/errno.h          |  2 +
 arch/parisc/include/uapi/asm/fcntl.h          |  1 +
 arch/sparc/include/uapi/asm/errno.h           |  2 +
 arch/sparc/include/uapi/asm/fcntl.h           |  1 +
 fs/fcntl.c                                    |  2 +-
 fs/namei.c                                    |  6 +++
 fs/open.c                                     |  4 +-
 include/linux/fcntl.h                         |  2 +-
 include/uapi/asm-generic/errno.h              |  2 +
 include/uapi/asm-generic/fcntl.h              |  4 ++
 tools/arch/alpha/include/uapi/asm/errno.h     |  2 +
 tools/arch/mips/include/uapi/asm/errno.h      |  2 +
 tools/arch/parisc/include/uapi/asm/errno.h    |  2 +
 tools/arch/sparc/include/uapi/asm/errno.h     |  2 +
 tools/include/uapi/asm-generic/errno.h        |  2 +
 .../testing/selftests/openat2/openat2_test.c  | 37 ++++++++++++++++++-
 19 files changed, 74 insertions(+), 4 deletions(-)

-- 
2.52.0