SUNRPC: Convert the credential garbage collector into a shrinker callback

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 45 insertions, 18 deletions

diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index cf1198d10ee9..81f4c776c558 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -26,6 +26,7 @@ static const struct rpc_authops *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
 };
 
 static LIST_HEAD(cred_unused);
+static unsigned long number_cred_unused;
 
 static u32
 pseudoflavor_to_flavor(u32 flavor) {
@@ -136,7 +137,7 @@ rpcauth_unhash_cred(struct rpc_cred *cred)
  * Initialize RPC credential cache
  */
 int
-rpcauth_init_credcache(struct rpc_auth *auth, unsigned long expire)
+rpcauth_init_credcache(struct rpc_auth *auth)
 {
         struct rpc_cred_cache *new;
         int i;
@@ -147,8 +148,6 @@ rpcauth_init_credcache(struct rpc_auth *auth, unsigned long expire)
         for (i = 0; i < RPC_CREDCACHE_NR; i++)
                 INIT_HLIST_HEAD(&new->hashtable[i]);
         spin_lock_init(&new->lock);
-        new->expire = expire;
-        new->nextgc = jiffies + (expire >> 1);
         auth->au_credcache = new;
         return 0;
 }
@@ -187,7 +186,11 @@ rpcauth_clear_credcache(struct rpc_cred_cache *cache)
                 while (!hlist_empty(head)) {
                         cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
                         get_rpccred(cred);
-                        list_move_tail(&cred->cr_lru, &free);
+                        if (!list_empty(&cred->cr_lru)) {
+                                list_del(&cred->cr_lru);
+                                number_cred_unused--;
+                        }
+                        list_add_tail(&cred->cr_lru, &free);
                         rpcauth_unhash_cred_locked(cred);
                 }
         }
@@ -214,18 +217,16 @@ rpcauth_destroy_credcache(struct rpc_auth *auth)
 /*
  * Remove stale credentials. Avoid sleeping inside the loop.
  */
-static void
-rpcauth_prune_expired(struct list_head *free)
+static int
+rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
 {
         spinlock_t *cache_lock;
         struct rpc_cred *cred;
 
         while (!list_empty(&cred_unused)) {
                 cred = list_entry(cred_unused.next, struct rpc_cred, cr_lru);
-                if (time_after(jiffies, cred->cr_expire +
-                                        cred->cr_auth->au_credcache->expire))
-                        break;
                 list_del_init(&cred->cr_lru);
+                number_cred_unused--;
                 if (atomic_read(&cred->cr_count) != 0)
                         continue;
                 cache_lock = &cred->cr_auth->au_credcache->lock;
@@ -234,23 +235,32 @@ rpcauth_prune_expired(struct list_head *free)
                         get_rpccred(cred);
                         list_add_tail(&cred->cr_lru, free);
                         rpcauth_unhash_cred_locked(cred);
+                        nr_to_scan--;
                 }
                 spin_unlock(cache_lock);
+                if (nr_to_scan == 0)
+                        break;
         }
+        return nr_to_scan;
 }
 
 /*
- * Run garbage collector.
+ * Run memory cache shrinker.
  */
-static void
-rpcauth_gc_credcache(struct rpc_cred_cache *cache, struct list_head *free)
+static int
+rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
 {
-        if (list_empty(&cred_unused) || time_before(jiffies, cache->nextgc))
-                return;
+        LIST_HEAD(free);
+        int res;
+
+        if (list_empty(&cred_unused))
+                return 0;
         spin_lock(&rpc_credcache_lock);
-        cache->nextgc = jiffies + cache->expire;
-        rpcauth_prune_expired(free);
+        nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
+        res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
         spin_unlock(&rpc_credcache_lock);
+        rpcauth_destroy_credlist(&free);
+        return res;
 }
 
 /*
@@ -318,7 +328,6 @@ found:
                         cred = ERR_PTR(res);
                 }
         }
-        rpcauth_gc_credcache(cache, &free);
         rpcauth_destroy_credlist(&free);
 out:
         return cred;
@@ -408,13 +417,16 @@ put_rpccred(struct rpc_cred *cred)
 need_lock:
         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
                 return;
-        if (!list_empty(&cred->cr_lru))
+        if (!list_empty(&cred->cr_lru)) {
+                number_cred_unused--;
                 list_del_init(&cred->cr_lru);
+        }
         if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
                 rpcauth_unhash_cred(cred);
         else if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
                 cred->cr_expire = jiffies;
                 list_add_tail(&cred->cr_lru, &cred_unused);
+                number_cred_unused++;
                 spin_unlock(&rpc_credcache_lock);
                 return;
         }
@@ -520,3 +532,18 @@ rpcauth_uptodatecred(struct rpc_task *task)
         return cred == NULL ||
                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
 }
+
+
+static struct shrinker *rpc_cred_shrinker;
+
+void __init rpcauth_init_module(void)
+{
+        rpc_init_authunix();
+        rpc_cred_shrinker = set_shrinker(DEFAULT_SEEKS, rpcauth_cache_shrinker);
+}
+
+void __exit rpcauth_remove_module(void)
+{
+        if (rpc_cred_shrinker != NULL)
+                remove_shrinker(rpc_cred_shrinker);
+}