[PATCH 1/1 fyi] tools headers uapi: Sync linux/fcntl.h with the kernel sources

[Arnaldo Carvalho de Melo <acme@kernel.org>]

tldr; Just FYI, I'm carrying this on the perf tools tree.

- Arnaldo

Full explanation:

There used to be no copies, with tools/ code using kernel headers
directly. From time to time tools/perf/ broke due to legitimate kernel
hacking. At some point Linus complained about such direct usage. Then we
adopted the current model.

The way these headers are used in perf are not restricted to just
including them to compile something.

There are sometimes used in scripts that convert defines into string
tables, etc, so some change may break one of these scripts, or new MSRs
may use some different #define pattern, etc.

E.g.:

  $ ls -1 tools/perf/trace/beauty/*.sh | head -5
  tools/perf/trace/beauty/arch_errno_names.sh
  tools/perf/trace/beauty/drm_ioctl.sh
  tools/perf/trace/beauty/fadvise.sh
  tools/perf/trace/beauty/fsconfig.sh
  tools/perf/trace/beauty/fsmount.sh
  $
  $ tools/perf/trace/beauty/fadvise.sh
  static const char *fadvise_advices[] = {
  	[0] = "NORMAL",
  	[1] = "RANDOM",
  	[2] = "SEQUENTIAL",
  	[3] = "WILLNEED",
  	[4] = "DONTNEED",
  	[5] = "NOREUSE",
  };
  $

The tools/perf/check-headers.sh script, part of the tools/ build
process, points out changes in the original files.

So its important not to touch the copies in tools/ when doing changes in
the original kernel headers, that will be done later, when
check-headers.sh inform about the change to the perf tools hackers.

---

To get the changes in:

  96b2b072ee62be8a ("exportfs: allow exporting non-decodeable file handles to userspace")

That don't add anything that is handled by existing hard coded tables or
table generation scripts.

This silences this perf build warning:

  Warning: Kernel ABI header differences:
    diff -u tools/include/uapi/linux/fcntl.h include/uapi/linux/fcntl.h

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/include/uapi/linux/fcntl.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/include/uapi/linux/fcntl.h b/tools/include/uapi/linux/fcntl.h
index e8c07da58c9f20ed..6c80f96049bd07d1 100644
--- a/tools/include/uapi/linux/fcntl.h
+++ b/tools/include/uapi/linux/fcntl.h
@@ -112,4 +112,9 @@
 
 #define AT_RECURSIVE		0x8000	/* Apply to the entire subtree */
 
+/* Flags for name_to_handle_at(2). We reuse AT_ flag space to save bits... */
+#define AT_HANDLE_FID		AT_REMOVEDIR	/* file handle is needed to
+					compare object identity and may not
+					be usable to open_by_handle_at(2) */
+
 #endif /* _UAPI_LINUX_FCNTL_H */
-- 
2.37.1