Re: [PATCH bpf-next v6 0/5] libbpf: Support automatic pinning of maps using 'pinning' BTF attribute

["Toke Høiland-Jørgensen" <toke@redhat.com>]

Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:

> On Sat, Nov 2, 2019 at 4:09 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> This series adds support to libbpf for reading 'pinning' settings from BTF-based
>> map definitions. It introduces a new open option which can set the pinning path;
>> if no path is set, /sys/fs/bpf is used as the default. Callers can customise the
>> pinning between open and load by setting the pin path per map, and still get the
>> automatic reuse feature.
>>
>> The semantics of the pinning is similar to the iproute2 "PIN_GLOBAL" setting,
>> and the eventual goal is to move the iproute2 implementation to be based on
>> libbpf and the functions introduced in this series.
>>
>> Changelog:
>>
>> v6:
>>   - Fix leak of struct bpf_object in selftest
>>   - Make struct bpf_map arg const in bpf_map__is_pinned() and bpf_map__get_pin_path()
>>
>> v5:
>>   - Don't pin maps with pinning set, but with a value of LIBBPF_PIN_NONE
>>   - Add a few more selftests:
>>     - Should not pin map with pinning set, but value LIBBPF_PIN_NONE
>>     - Should fail to load a map with an invalid pinning value
>>     - Should fail to re-use maps with parameter mismatch
>>   - Alphabetise libbpf.map
>>   - Whitespace and typo fixes
>>
>> v4:
>>   - Don't check key_type_id and value_type_id when checking for map reuse
>>     compatibility.
>>   - Move building of map->pin_path into init_user_btf_map()
>>   - Get rid of 'pinning' attribute in struct bpf_map
>>   - Make sure we also create parent directory on auto-pin (new patch 3).
>>   - Abort the selftest on error instead of attempting to continue.
>>   - Support unpinning all pinned maps with bpf_object__unpin_maps(obj, NULL)
>>   - Support pinning at map->pin_path with bpf_object__pin_maps(obj, NULL)
>>   - Make re-pinning a map at the same path a noop
>>   - Rename the open option to pin_root_path
>>   - Add a bunch more self-tests for pin_maps(NULL) and unpin_maps(NULL)
>>   - Fix a couple of smaller nits
>>
>> v3:
>>   - Drop bpf_object__pin_maps_opts() and just use an open option to customise
>>     the pin path; also don't touch bpf_object__{un,}pin_maps()
>>   - Integrate pinning and reuse into bpf_object__create_maps() instead of having
>>     multiple loops though the map structure
>>   - Make errors in map reuse and pinning fatal to the load procedure
>>   - Add selftest to exercise pinning feature
>>   - Rebase series to latest bpf-next
>>
>> v2:
>>   - Drop patch that adds mounting of bpffs
>>   - Only support a single value of the pinning attribute
>>   - Add patch to fixup error handling in reuse_fd()
>>   - Implement the full automatic pinning and map reuse logic on load
>>
>> ---
>>
>> Toke Høiland-Jørgensen (5):
>>       libbpf: Fix error handling in bpf_map__reuse_fd()
>>       libbpf: Store map pin path and status in struct bpf_map
>>       libbpf: Move directory creation into _pin() functions
>>       libbpf: Add auto-pinning of maps when loading BPF objects
>>       selftests: Add tests for automatic map pinning
>>
>>
>
> For the series:
>
> Acked-by: Andrii Nakryiko <andriin@fb.com>

Awesome! Thank you for your thorough reviews :)

-Toke