samples/bpf: Replace blk_account_io_done() with __blk_account_io_done()

Since commit be6bfe36db17 ("block: inline hot paths of blk_account_io_*()")
blk_account_io_*() become inline functions.

Signed-off-by: Rong Tao <rtoax@foxmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/tencent_1CC476835C219FACD84B6715F0D785517E07@qq.com

samples: bpf: Fix broken bpf programs due to removed symbol

>From commit f1394b798814 ("block: mark blk_account_io_completion
static") symbol blk_account_io_completion() has been marked as static,
which makes it no longer possible to attach kprobe to this event.
Currently, there are broken samples due to this reason.

As a solution to this, attach kprobe events to blk_account_io_done()
to modify them to perform the same behavior as before.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200818051641.21724-1-danieltimlee@gmail.com

samples/bpf: Use consistent include paths for libbpf

Fix all files in samples/bpf to include libbpf header files with the bpf/
prefix, to be consistent with external users of the library. Also ensure
that all includes of exported libbpf header files (those that are exported
on 'make install' of the library) use bracketed includes instead of quoted.

To make sure no new files are introduced that doesn't include the bpf/
prefix in its include, remove tools/lib/bpf from the include path entirely,
and use tools/lib instead.

Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157952560911.1683545.8795966751309534150.stgit@toke.dk

samples: bpf: fix: broken sample regarding removed function

Currently, running sample "task_fd_query" and "tracex3" occurs the
following error. On kernel v5.0-rc* this sample will be unavailable
due to the removal of function 'blk_start_request' at commit "a1ce35f".
(function removed, as "Single Queue IO scheduler" no longer exists)

$ sudo ./task_fd_query
failed to create kprobe 'blk_start_request' error 'No such file or
directory'

This commit will change the function 'blk_start_request' to
'blk_mq_start_request' to fix the broken sample.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

samples/bpf: add a samples/bpf test for BPF_TASK_FD_QUERY

This is mostly to test kprobe/uprobe which needs kernel headers.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>