[PATCH v2 bpf-next 0/9] add bpf batch ops to process more than 1 elem

[Brian Vazquez <brianvv@google.com>]

This patch series introduce batch ops that can be added to bpf maps to
lookup/lookup_and_delete/update/delete more than 1 element at the time,
this is specially useful when syscall overhead is a problem and in case
of hmap it will provide a reliable way of traversing them.

The implementation inclues a generic approach that could potentially be
used by any bpf map and adds it to arraymap, it also includes the specific
implementation of hashmaps which are traversed using buckets instead
of keys.

The bpf syscall subcommands introduced are:

  BPF_MAP_LOOKUP_BATCH
  BPF_MAP_LOOKUP_AND_DELETE_BATCH
  BPF_MAP_UPDATE_BATCH
  BPF_MAP_DELETE_BATCH

The UAPI attribute is:

  struct { /* struct used by BPF_MAP_*_BATCH commands */
         __aligned_u64   in_batch;       /* start batch,
                                          * NULL to start from beginning
                                          */
         __aligned_u64   out_batch;      /* output: next start batch */
         __aligned_u64   keys;
         __aligned_u64   values;
         __u32           count;          /* input/output:
                                          * input: # of key/value
                                          * elements
                                          * output: # of filled elements
                                          */
         __u32           map_fd;
         __u64           elem_flags;
         __u64           flags;
  } batch;


in_batch and out_batch are only used for lookup and lookup_and_delete since
those are the only two operations that attempt to traverse the map.

update/delete batch ops should provide the keys/values that user wants
to modify.

Here are the previous discussions on the batch processing:
 - https://lore.kernel.org/bpf/20190724165803.87470-1-brianvv@google.com/
 - https://lore.kernel.org/bpf/20190829064502.2750303-1-yhs@fb.com/
 - https://lore.kernel.org/bpf/20190906225434.3635421-1-yhs@fb.com/

Changelog since v1:
 - Fix SOB ordering and remove Co-authored-by tag (Alexei)

Changelog since RFC:
 - Change batch to in_batch and out_batch to support more flexible opaque
   values to iterate the bpf maps.
 - Remove update/delete specific batch ops for htab and use the generic
   implementations instead.

Brian Vazquez (5):
  bpf: add bpf_map_{value_size,update_value,map_copy_value} functions
  bpf: add generic support for lookup and lookup_and_delete batch ops
  bpf: add generic support for update and delete batch ops
  bpf: add lookup and updated batch ops to arraymap
  selftests/bpf: add batch ops testing to array bpf map

Yonghong Song (4):
  bpf: add batch ops to all htab bpf map
  tools/bpf: sync uapi header bpf.h
  libbpf: add libbpf support to batch ops
  selftests/bpf: add batch ops testing for hmap and hmap_percpu

 include/linux/bpf.h                           |  21 +
 include/uapi/linux/bpf.h                      |  21 +
 kernel/bpf/arraymap.c                         |   2 +
 kernel/bpf/hashtab.c                          | 244 ++++++++
 kernel/bpf/syscall.c                          | 571 ++++++++++++++----
 tools/include/uapi/linux/bpf.h                |  21 +
 tools/lib/bpf/bpf.c                           |  61 ++
 tools/lib/bpf/bpf.h                           |  14 +
 tools/lib/bpf/libbpf.map                      |   4 +
 .../map_lookup_and_delete_batch_array.c       | 119 ++++
 .../map_lookup_and_delete_batch_htab.c        | 257 ++++++++
 11 files changed, 1215 insertions(+), 120 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/map_tests/map_lookup_and_delete_batch_array.c
 create mode 100644 tools/testing/selftests/bpf/map_tests/map_lookup_and_delete_batch_htab.c

-- 
2.24.0.432.g9d3f5f5b63-goog