Merge branch 'bpf-introduce-new-vfs-based-bpf-kfuncs'

Matt Bobrowski says:

====================
bpf: introduce new VFS based BPF kfuncs

G'day!

A respin based off v3, which can be found here [0]. Original
motivations for introducing this suite of BPF kfuncs can be found here
[1].

The primary difference in this version of the patch series is that the
suite of VFS related BPF kfuncs added can be used from both sleepable
and non-sleepable BPF LSM program types. IOW, the KF_SLEEPABLE
annotation has been removed from all of them.

Changes sinve v3:

* KF_SLEEPABLE annotation has been dropped from all newly introduced
  VFS related BPF kfuncs. This includes bpf_get_task_exe_file(),
  bpf_put_file(), and bpf_path_d_path(). Both negative and positive
  selftests backing these new BPF kfuncs have also been updated
  accordingly.

* buf__sz conditional in bpf_path_d_path() has been updated from
  buf__sz <= 0, to !buf__sz.

* Syntax issues as reported so here [2] have been corrected.

[0] https://lore.kernel.org/bpf/20240726085604.2369469-1-mattbobrowski@google.com/
[1] https://lore.kernel.org/bpf/cover.1708377880.git.mattbobrowski@google.com/#t
[2] https://netdev.bots.linux.dev/static/nipa/874023/13742510/checkpatch/stdout
====================

Link: https://lore.kernel.org/r/20240731110833.1834742-1-mattbobrowski@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>