Re: [PATCH v2] vfs: add RWF_NOAPPEND flag for pwritev2

On Fri, Jan 19, 2024 at 03:33:32PM +0100, Christian Brauner wrote:

On Mon, 31 Aug 2020 11:32:08 -0400, Rich Felker wrote:

quoted

The pwrite function, originally defined by POSIX (thus the "p"), is
defined to ignore O_APPEND and write at the offset passed as its
argument. However, historically Linux honored O_APPEND if set and
ignored the offset. This cannot be changed due to stability policy,
but is documented in the man page as a bug.

Now that there's a pwritev2 syscall providing a superset of the pwrite
functionality that has a flags argument, the conforming behavior can
be offered to userspace via a new flag. Since pwritev2 checks flag
validity (in kiocb_set_rw_flags) and reports unknown ones with
EOPNOTSUPP, callers will not get wrong behavior on old kernels that
don't support the new flag; the error is reported and the caller can
decide how to handle it.

[...]

The RWF_* and IOCB_* flags were
aligned so they could be set in one operation. So there was a merge
conflict when applying. I've resolved it. Please take a look and make
sure that it's all correct.

---

Applied to the vfs.misc branch of the vfs/vfs.git tree.
Patches in the vfs.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.misc

[1/1] vfs: add RWF_NOAPPEND flag for pwritev2
      https://git.kernel.org/vfs/vfs/c/31081ab305a1

LGTM. Thanks!