bpf: Extend batch operations for map-in-map bpf-maps

This patch extends batch operations support for map-in-map map-types:
BPF_MAP_TYPE_HASH_OF_MAPS and BPF_MAP_TYPE_ARRAY_OF_MAPS

A usecase where outer HASH map holds hundred of VIP entries and its
associated reuse-ports per VIP stored in REUSEPORT_SOCKARRAY type
inner map, needs to do batch operation for performance gain.

This patch leverages the exiting generic functions for most of the batch
operations. As map-in-map's value contains the actual reference of the inner map,
for BPF_MAP_TYPE_HASH_OF_MAPS type, it needed an extra step to fetch the
map_id from the reference value.

selftests are added in next patch 2/2.

Signed-off-by: Takshak Chahande <ctakshak@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220510082221.2390540-1-ctakshak@fb.com

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index b3bf31fd94581fd50a8e32378d67ad44a41fc0f3..724613da6576ac1edd4c7bdc9b0952d381554e65 100644 (file)
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -1345,6 +1345,8 @@ const struct bpf_map_ops array_of_maps_map_ops = {
        .map_fd_put_ptr = bpf_map_fd_put_ptr,
        .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
        .map_gen_lookup = array_of_map_gen_lookup,
+       .map_lookup_batch = generic_map_lookup_batch,
+       .map_update_batch = generic_map_update_batch,
        .map_check_btf = map_check_no_btf,
        .map_btf_id = &array_map_btf_ids[0],
 };

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 3e00e62b2218584470b76cbf3bc24f855ab3196f..705841279d1622421c28afa587598f8cf40244a5 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -140,7 +140,7 @@ static inline bool htab_use_raw_lock(const struct bpf_htab *htab)
 
 static void htab_init_buckets(struct bpf_htab *htab)
 {
-       unsigned i;
+       unsigned int i;
 
        for (i = 0; i < htab->n_buckets; i++) {
                INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
@@ -1627,7 +1627,7 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map,
        void __user *uvalues = u64_to_user_ptr(attr->batch.values);
        void __user *ukeys = u64_to_user_ptr(attr->batch.keys);
        void __user *ubatch = u64_to_user_ptr(attr->batch.in_batch);
-       u32 batch, max_count, size, bucket_size;
+       u32 batch, max_count, size, bucket_size, map_id;
        struct htab_elem *node_to_free = NULL;
        u64 elem_map_flags, map_flags;
        struct hlist_nulls_head *head;
@@ -1752,6 +1752,14 @@ again_nocopy:
                        }
                } else {
                        value = l->key + roundup_key_size;
+                       if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
+                               struct bpf_map **inner_map = value;
+
+                                /* Actual value is the id of the inner map */
+                               map_id = map->ops->map_fd_sys_lookup_elem(*inner_map);
+                               value = &map_id;
+                       }
+
                        if (elem_map_flags & BPF_F_LOCK)
                                copy_map_value_locked(map, dst_val, value,
                                                      true);
@@ -2450,5 +2458,6 @@ const struct bpf_map_ops htab_of_maps_map_ops = {
        .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
        .map_gen_lookup = htab_of_map_gen_lookup,
        .map_check_btf = map_check_no_btf,
+       BATCH_OPS(htab),
        .map_btf_id = &htab_map_btf_ids[0],
 };