[PATCH] knfsd: Change the store of auth_domains to not be a 'cache'

The 'auth_domain's are simply handles on internal data structures.  They do
not cache information from user-space, and forcing them into the mold of a
'cache' misrepresents their true nature and causes confusion.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/nfsd/export.c

@@ -242,7 +242,7 @@ static inline int svc_expkey_match (struct svc_expkey *a, struct svc_expkey *b)
 
 static inline void svc_expkey_init(struct svc_expkey *new, struct svc_expkey *item)
 {
-	cache_get(&item->ek_client->h);
+	kref_get(&item->ek_client->ref);
 	new->ek_client = item->ek_client;
 	new->ek_fsidtype = item->ek_fsidtype;
 	new->ek_fsid[0] = item->ek_fsid[0];
@@ -474,7 +474,7 @@ static inline int svc_export_match(struct svc_export *a, struct svc_export *b)
 }
 static inline void svc_export_init(struct svc_export *new, struct svc_export *item)
 {
-	cache_get(&item->ex_client->h);
+	kref_get(&item->ex_client->ref);
 	new->ex_client = item->ex_client;
 	new->ex_dentry = dget(item->ex_dentry);
 	new->ex_mnt = mntget(item->ex_mnt);
@@ -1129,7 +1129,6 @@ exp_delclient(struct nfsctl_client *ncp)
 	 */
 	if (dom) {
 		err = auth_unix_forget_old(dom);
-		dom->h.expiry_time = get_seconds();
 		auth_domain_put(dom);
 	}
 

include/linux/sunrpc/svcauth.h

@@ -45,9 +45,10 @@ struct svc_rqst;		/* forward decl */
  * of ip addresses to the given client.
  */
 struct auth_domain {
-	struct	cache_head	h;
+	struct kref		ref;
+	struct hlist_node	hash;
 	char			*name;
-	int			flavour;
+	struct auth_ops		*flavour;
 };
 
 /*
@@ -86,6 +87,9 @@ struct auth_domain {
  *
  * domain_release()
  *   This call releases a domain.
+ * set_client()
+ *   Givens a pending request (struct svc_rqst), finds and assigns
+ *   an appropriate 'auth_domain' as the client.
  */
 struct auth_ops {
 	char *	name;
@@ -117,7 +121,7 @@ extern void	svc_auth_unregister(rpc_authflavor_t flavor);
 extern struct auth_domain *unix_domain_find(char *name);
 extern void auth_domain_put(struct auth_domain *item);
 extern int auth_unix_add_addr(struct in_addr addr, struct auth_domain *dom);
-extern struct auth_domain *auth_domain_lookup(struct auth_domain *item, int set);
+extern struct auth_domain *auth_domain_lookup(char *name, struct auth_domain *new);
 extern struct auth_domain *auth_domain_find(char *name);
 extern struct auth_domain *auth_unix_lookup(struct in_addr addr);
 extern int auth_unix_forget_old(struct auth_domain *dom);
@@ -160,8 +164,6 @@ static inline unsigned long hash_mem(char *buf, int length, int bits)
 	return hash >> (BITS_PER_LONG - bits);
 }
 
-extern struct cache_detail auth_domain_cache, ip_map_cache;
-
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_SUNRPC_SVCAUTH_H_ */

net/sunrpc/auth_gss/svcauth_gss.c

@@ -645,6 +645,8 @@ find_gss_auth_domain(struct gss_ctx *ctx, u32 svc)
 	return auth_domain_find(name);
 }
 
+static struct auth_ops svcauthops_gss;
+
 int
 svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name)
 {
@@ -655,20 +657,18 @@ svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name)
 	new = kmalloc(sizeof(*new), GFP_KERNEL);
 	if (!new)
 		goto out;
-	cache_init(&new->h.h);
+	kref_init(&new->h.ref);
 	new->h.name = kmalloc(strlen(name) + 1, GFP_KERNEL);
 	if (!new->h.name)
 		goto out_free_dom;
 	strcpy(new->h.name, name);
-	new->h.flavour = RPC_AUTH_GSS;
+	new->h.flavour = &svcauthops_gss;
 	new->pseudoflavor = pseudoflavor;
-	new->h.h.expiry_time = NEVER;
 
-	test = auth_domain_lookup(&new->h, 1);
-	if (test == &new->h) {
-		BUG_ON(atomic_dec_and_test(&new->h.h.refcnt));
-	} else { /* XXX Duplicate registration? */
+	test = auth_domain_lookup(name, &new->h);
+	if (test != &new->h) { /* XXX Duplicate registration? */
 		auth_domain_put(&new->h);
+		/* dangling ref-count... */
 		goto out;
 	}
 	return 0;

net/sunrpc/sunrpc_syms.c

@@ -142,6 +142,7 @@ EXPORT_SYMBOL(nlm_debug);
 
 extern int register_rpc_pipefs(void);
 extern void unregister_rpc_pipefs(void);
+extern struct cache_detail ip_map_cache;
 
 static int __init
 init_sunrpc(void)
@@ -158,7 +159,6 @@ init_sunrpc(void)
 #ifdef CONFIG_PROC_FS
 	rpc_proc_init();
 #endif
-	cache_register(&auth_domain_cache);
 	cache_register(&ip_map_cache);
 out:
 	return err;
@@ -169,8 +169,6 @@ cleanup_sunrpc(void)
 {
 	unregister_rpc_pipefs();
 	rpc_destroy_mempool();
-	if (cache_unregister(&auth_domain_cache))
-		printk(KERN_ERR "sunrpc: failed to unregister auth_domain cache\n");
 	if (cache_unregister(&ip_map_cache))
 		printk(KERN_ERR "sunrpc: failed to unregister ip_map cache\n");
 #ifdef RPC_DEBUG

net/sunrpc/svcauth.c

@@ -106,112 +106,56 @@ svc_auth_unregister(rpc_authflavor_t flavor)
 EXPORT_SYMBOL(svc_auth_unregister);
 
 /**************************************************
- * cache for domain name to auth_domain
- * Entries are only added by flavours which will normally
- * have a structure that 'inherits' from auth_domain.
- * e.g. when an IP -> domainname is given to  auth_unix,
- * and the domain name doesn't exist, it will create a
- * auth_unix_domain and add it to this hash table.
- * If it finds the name does exist, but isn't AUTH_UNIX,
- * it will complain.
+ * 'auth_domains' are stored in a hash table indexed by name.
+ * When the last reference to an 'auth_domain' is dropped,
+ * the object is unhashed and freed.
+ * If auth_domain_lookup fails to find an entry, it will return
+ * it's second argument 'new'.  If this is non-null, it will
+ * have been atomically linked into the table.
  */
 
-/*
- * Auth auth_domain cache is somewhat different to other caches,
- * largely because the entries are possibly of different types:
- * each auth flavour has it's own type.
- * One consequence of this that DefineCacheLookup cannot
- * allocate a new structure as it cannot know the size.
- * Notice that the "INIT" code fragment is quite different
- * from other caches.  When auth_domain_lookup might be
- * creating a new domain, the new domain is passed in
- * complete and it is used as-is rather than being copied into
- * another structure.
- */
 #define	DN_HASHBITS	6
 #define	DN_HASHMAX	(1<<DN_HASHBITS)
 #define	DN_HASHMASK	(DN_HASHMAX-1)
 
-static struct cache_head	*auth_domain_table[DN_HASHMAX];
-
-static void auth_domain_drop(struct cache_head *item, struct cache_detail *cd)
-{
-	struct auth_domain *dom = container_of(item, struct auth_domain, h);
-	if (cache_put(item,cd))
-		authtab[dom->flavour]->domain_release(dom);
-}
-
-
-struct cache_detail auth_domain_cache = {
-	.owner		= THIS_MODULE,
-	.hash_size	= DN_HASHMAX,
-	.hash_table	= auth_domain_table,
-	.name		= "auth.domain",
-	.cache_put	= auth_domain_drop,
-};
+static struct hlist_head	auth_domain_table[DN_HASHMAX];
+static spinlock_t	auth_domain_lock = SPIN_LOCK_UNLOCKED;
 
 void auth_domain_put(struct auth_domain *dom)
 {
-	auth_domain_drop(&dom->h, &auth_domain_cache);
-}
-
-static inline int auth_domain_hash(struct auth_domain *item)
-{
-	return hash_str(item->name, DN_HASHBITS);
-}
-static inline int auth_domain_match(struct auth_domain *tmp, struct auth_domain *item)
-{
-	return strcmp(tmp->name, item->name) == 0;
+	if (atomic_dec_and_lock(&dom->ref.refcount, &auth_domain_lock)) {
+		hlist_del(&dom->hash);
+		dom->flavour->domain_release(dom);
+	}
 }
 
 struct auth_domain *
-auth_domain_lookup(struct auth_domain *item, int set)
+auth_domain_lookup(char *name, struct auth_domain *new)
 {
-	struct auth_domain *tmp = NULL;
-	struct cache_head **hp, **head;
-	head = &auth_domain_cache.hash_table[auth_domain_hash(item)];
-
-	if (set)
-		write_lock(&auth_domain_cache.hash_lock);
-	else
-		read_lock(&auth_domain_cache.hash_lock);
-	for (hp=head; *hp != NULL; hp = &tmp->h.next) {
-		tmp = container_of(*hp, struct auth_domain, h);
-		if (!auth_domain_match(tmp, item))
-			continue;
-		if (!set) {
-			cache_get(&tmp->h);
-			goto out_noset;
+	struct auth_domain *hp;
+	struct hlist_head *head;
+	struct hlist_node *np;
+
+	head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
+
+	spin_lock(&auth_domain_lock);
+
+	hlist_for_each_entry(hp, np, head, hash) {
+		if (strcmp(hp->name, name)==0) {
+			kref_get(&hp->ref);
+			spin_unlock(&auth_domain_lock);
+			return hp;
+		}
 	}
-		*hp = tmp->h.next;
-		tmp->h.next = NULL;
-		auth_domain_drop(&tmp->h, &auth_domain_cache);
-		goto out_set;
+	if (new) {
+		hlist_add_head(&new->hash, head);
+		kref_get(&new->ref);
 	}
-	/* Didn't find anything */
-	if (!set)
-		goto out_nada;
-	auth_domain_cache.entries++;
-out_set:
-	item->h.next = *head;
-	*head = &item->h;
-	cache_get(&item->h);
-	write_unlock(&auth_domain_cache.hash_lock);
-	cache_fresh(&auth_domain_cache, &item->h, item->h.expiry_time);
-	cache_get(&item->h);
-	return item;
-out_nada:
-	tmp = NULL;
-out_noset:
-	read_unlock(&auth_domain_cache.hash_lock);
-	return tmp;
+	spin_unlock(&auth_domain_lock);
+	return new;
 }
 
 struct auth_domain *auth_domain_find(char *name)
 {
-	struct auth_domain *rv, ad;
-
-	ad.name = name;
-	rv = auth_domain_lookup(&ad, 0);
-	return rv;
+	return auth_domain_lookup(name, NULL);
 }

net/sunrpc/svcauth_unix.c

@@ -27,17 +27,20 @@ struct unix_domain {
 	/* other stuff later */
 };
 
+extern struct auth_ops svcauth_unix;
+
 struct auth_domain *unix_domain_find(char *name)
 {
-	struct auth_domain *rv, ud;
-	struct unix_domain *new;
-
-	ud.name = name;
-	
-	rv = auth_domain_lookup(&ud, 0);
+	struct auth_domain *rv;
+	struct unix_domain *new = NULL;
 
- foundit:
-	if (rv && rv->flavour != RPC_AUTH_UNIX) {
+	rv = auth_domain_lookup(name, NULL);
+	while(1) {
+		if (rv != &new->h) {
+			if (new) auth_domain_put(&new->h);
+			return rv;
+		}
+		if (rv && rv->flavour != &svcauth_unix) {
 			auth_domain_put(rv);
 			return NULL;
 		}
@@ -47,21 +50,12 @@ struct auth_domain *unix_domain_find(char *name)
 		new = kmalloc(sizeof(*new), GFP_KERNEL);
 		if (new == NULL)
 			return NULL;
-	cache_init(&new->h.h);
+		kref_init(&new->h.ref);
 		new->h.name = kstrdup(name, GFP_KERNEL);
-	new->h.flavour = RPC_AUTH_UNIX;
+		new->h.flavour = &svcauth_unix;
 		new->addr_changes = 0;
-	new->h.h.expiry_time = NEVER;
-
-	rv = auth_domain_lookup(&new->h, 2);
-	if (rv == &new->h) {
-		if (atomic_dec_and_test(&new->h.h.refcnt)) BUG();
-	} else {
-		auth_domain_put(&new->h);
-		goto foundit;
+		rv = auth_domain_lookup(name, &new->h);
 	}
-
-	return rv;
 }
 
 static void svcauth_unix_domain_release(struct auth_domain *dom)
@@ -130,7 +124,7 @@ static inline void ip_map_init(struct ip_map *new, struct ip_map *item)
 }
 static inline void ip_map_update(struct ip_map *new, struct ip_map *item)
 {
-	cache_get(&item->m_client->h.h);
+	kref_get(&item->m_client->h.ref);
 	new->m_client = item->m_client;
 	new->m_add_change = item->m_add_change;
 }
@@ -272,7 +266,7 @@ int auth_unix_add_addr(struct in_addr addr, struct auth_domain *dom)
 	struct unix_domain *udom;
 	struct ip_map ip, *ipmp;
 
-	if (dom->flavour != RPC_AUTH_UNIX)
+	if (dom->flavour != &svcauth_unix)
 		return -EINVAL;
 	udom = container_of(dom, struct unix_domain, h);
 	strcpy(ip.m_class, "nfsd");
@@ -295,7 +289,7 @@ int auth_unix_forget_old(struct auth_domain *dom)
 {
 	struct unix_domain *udom;
 	
-	if (dom->flavour != RPC_AUTH_UNIX)
+	if (dom->flavour != &svcauth_unix)
 		return -EINVAL;
 	udom = container_of(dom, struct unix_domain, h);
 	udom->addr_changes++;
@@ -323,7 +317,7 @@ struct auth_domain *auth_unix_lookup(struct in_addr addr)
 		rv = NULL;
 	} else {
 		rv = &ipm->m_client->h;
-		cache_get(&rv->h);
+		kref_get(&rv->ref);
 	}
 	ip_map_put(&ipm->h, &ip_map_cache);
 	return rv;
@@ -332,7 +326,6 @@ struct auth_domain *auth_unix_lookup(struct in_addr addr)
 void svcauth_unix_purge(void)
 {
 	cache_purge(&ip_map_cache);
-	cache_purge(&auth_domain_cache);
 }
 
 static int
@@ -361,7 +354,7 @@ svcauth_unix_set_client(struct svc_rqst *rqstp)
 			return SVC_DENIED;
 		case 0:
 			rqstp->rq_client = &ipm->m_client->h;
-			cache_get(&rqstp->rq_client->h);
+			kref_get(&rqstp->rq_client->ref);
 			ip_map_put(&ipm->h, &ip_map_cache);
 			break;
 	}