[PATCH v3 bpf-next 1/2] bpf: Extend batch operations for map-in-map bpf-maps

[Takshak Chahande <ctakshak@fb.com>]

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 that has v1->v3 changes

Signed-off-by: Takshak Chahande <ctakshak@fb.com>
---
 kernel/bpf/arraymap.c |  2 ++
 kernel/bpf/hashtab.c  | 12 ++++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 7f145aefbff8..f0852b6617cc 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -1344,6 +1344,8 @@ 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_name = "bpf_array",
 	.map_btf_id = &array_of_maps_map_btf_id,
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index c68fbebc8c00..fd537bfba84c 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -139,7 +139,7 @@ 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);
@@ -1594,7 +1594,7 @@ __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;
@@ -1719,6 +1719,13 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map,
 			}
 		} 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);
@@ -2425,6 +2432,7 @@ 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_name = "bpf_htab",
 	.map_btf_id = &htab_of_maps_map_btf_id,
 };
-- 
2.30.2