[iptables PATCH v3 04/11] nft-cache: Introduce cache levels

[Phil Sutter]

Replace the simple have_cache boolean by a cache level indicator
defining how complete the cache is. Since have_cache indicated full
cache (including rules), make code depending on it check for cache level
NFT_CL_RULES.

Core cache fetching routine __nft_build_cache() accepts a new level via
parameter and raises cache completeness to that level.

Signed-off-by: Phil Sutter <p...@nwl.cc>
---
 iptables/nft-cache.c | 51 +++++++++++++++++++++++++++++++-------------
 iptables/nft.h       |  9 +++++++-
 2 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/iptables/nft-cache.c b/iptables/nft-cache.c
index 5444419a5cc3b..22a87e94efd76 100644
--- a/iptables/nft-cache.c
+++ b/iptables/nft-cache.c
@@ -224,30 +224,49 @@ static int fetch_rule_cache(struct nft_handle *h)
        return 0;
 }
 
-static void __nft_build_cache(struct nft_handle *h)
+static void __nft_build_cache(struct nft_handle *h, enum nft_cache_level level)
 {
        uint32_t genid_start, genid_stop;
 
+       if (level <= h->cache_level)
+               return;
 retry:
        mnl_genid_get(h, &genid_start);
-       fetch_table_cache(h);
-       fetch_chain_cache(h);
-       fetch_rule_cache(h);
-       h->have_cache = true;
-       mnl_genid_get(h, &genid_stop);
 
+       switch (h->cache_level) {
+       case NFT_CL_NONE:
+               fetch_table_cache(h);
+               if (level == NFT_CL_TABLES)
+                       break;
+               /* fall through */
+       case NFT_CL_TABLES:
+               fetch_chain_cache(h);
+               if (level == NFT_CL_CHAINS)
+                       break;
+               /* fall through */
+       case NFT_CL_CHAINS:
+               fetch_rule_cache(h);
+               if (level == NFT_CL_RULES)
+                       break;
+               /* fall through */
+       case NFT_CL_RULES:
+               break;
+       }
+
+       mnl_genid_get(h, &genid_stop);
        if (genid_start != genid_stop) {
                flush_chain_cache(h, NULL);
                goto retry;
        }
 
+       h->cache_level = level;
        h->nft_genid = genid_start;
 }
 
 void nft_build_cache(struct nft_handle *h)
 {
-       if (!h->have_cache)
-               __nft_build_cache(h);
+       if (h->cache_level < NFT_CL_RULES)
+               __nft_build_cache(h, NFT_CL_RULES);
 }
 
 void nft_fake_cache(struct nft_handle *h)
@@ -263,7 +282,7 @@ void nft_fake_cache(struct nft_handle *h)
 
                h->cache->table[type].chains = nftnl_chain_list_alloc();
        }
-       h->have_cache = true;
+       h->cache_level = NFT_CL_RULES;
        mnl_genid_get(h, &h->nft_genid);
 }
 
@@ -331,19 +350,22 @@ static int flush_cache(struct nft_handle *h, struct 
nft_cache *c,
 
 void flush_chain_cache(struct nft_handle *h, const char *tablename)
 {
-       if (!h->have_cache)
+       if (!h->cache_level)
                return;
 
        if (flush_cache(h, h->cache, tablename))
-               h->have_cache = false;
+               h->cache_level = NFT_CL_NONE;
 }
 
 void nft_rebuild_cache(struct nft_handle *h)
 {
-       if (h->have_cache)
+       enum nft_cache_level level = h->cache_level;
+
+       if (h->cache_level)
                __nft_flush_cache(h);
 
-       __nft_build_cache(h);
+       h->cache_level = NFT_CL_NONE;
+       __nft_build_cache(h, level);
 }
 
 void nft_release_cache(struct nft_handle *h)
@@ -354,8 +376,7 @@ void nft_release_cache(struct nft_handle *h)
 
 struct nftnl_table_list *nftnl_table_list_get(struct nft_handle *h)
 {
-       if (!h->cache->tables)
-               fetch_table_cache(h);
+       __nft_build_cache(h, NFT_CL_TABLES);
 
        return h->cache->tables;
 }
diff --git a/iptables/nft.h b/iptables/nft.h
index 451c266016d8d..9ae3122a1c515 100644
--- a/iptables/nft.h
+++ b/iptables/nft.h
@@ -27,6 +27,13 @@ struct builtin_table {
        struct builtin_chain chains[NF_INET_NUMHOOKS];
 };
 
+enum nft_cache_level {
+       NFT_CL_NONE,
+       NFT_CL_TABLES,
+       NFT_CL_CHAINS,
+       NFT_CL_RULES
+};
+
 struct nft_cache {
        struct nftnl_table_list         *tables;
        struct {
@@ -53,7 +60,7 @@ struct nft_handle {
        unsigned int            cache_index;
        struct nft_cache        __cache[2];
        struct nft_cache        *cache;
-       bool                    have_cache;
+       enum nft_cache_level    cache_level;
        bool                    restore;
        bool                    noflush;
        int8_t                  config_done;
-- 
2.23.0