NFS: DNS resolver cache per network namespace context introduced

This patch implements DNS resolver cache creation and registration for each
alive network namespace context.
This was done by registering NFS per-net operations, responsible for DNS cache
allocation/register and unregister/destructioning instead of initialization and
destruction of static "nfs_dns_resolve" cache detail (this one was removed).
Pointer to network dns resolver cache is stored in new per-net "nfs_net"
structure.
This patch also changes nfs_dns_resolve_name() function prototype (and it's
calls) by adding network pointer parameter, which is used to get proper DNS
resolver cache pointer for do_cache_lookup_wait() call.

Note: empty nfs_dns_resolver_init() and nfs_dns_resolver_destroy() functions
will be used in next patch in the series.

Signed-off-by: Stanislav Kinsbursky <[e-mail]>
Signed-off-by: Trond Myklebust <[e-mail]>

fs/nfs/dns_resolve.c

···
 #include <linux/sunrpc/clnt.h>
 #include <linux/dns_resolver.h>
 
-ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
+ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen,
 		struct sockaddr *sa, size_t salen)
 {
 	ssize_t ret;
···
 
 #include "dns_resolve.h"
 #include "cache_lib.h"
+#include "netns.h"
 
 #define NFS_DNS_HASHBITS 4
 #define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
-
-static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE];
 
 struct nfs_dns_ent {
 	struct cache_head h;
···
 	return ret;
 }
 
-static struct cache_detail nfs_dns_resolve = {
-	.owner = THIS_MODULE,
-	.hash_size = NFS_DNS_HASHTBL_SIZE,
-	.hash_table = nfs_dns_table,
-	.name = "dns_resolve",
-	.cache_put = nfs_dns_ent_put,
-	.cache_upcall = nfs_dns_upcall,
-	.cache_parse = nfs_dns_parse,
-	.cache_show = nfs_dns_show,
-	.match = nfs_dns_match,
-	.init = nfs_dns_ent_init,
-	.update = nfs_dns_ent_update,
-	.alloc = nfs_dns_ent_alloc,
-};
-
 static int do_cache_lookup(struct cache_detail *cd,
 		struct nfs_dns_ent *key,
 		struct nfs_dns_ent **item,
···
 	return ret;
 }
 
-ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
-		struct sockaddr *sa, size_t salen)
+ssize_t nfs_dns_resolve_name(struct net *net, char *name,
+		size_t namelen, struct sockaddr *sa, size_t salen)
 {
 	struct nfs_dns_ent key = {
 		.hostname = name,
···
 	};
 	struct nfs_dns_ent *item = NULL;
 	ssize_t ret;
+	struct nfs_net *nn = net_generic(net, nfs_net_id);
 
-	ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item);
+	ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
 	if (ret == 0) {
 		if (salen >= item->addrlen) {
 			memcpy(sa, &item->addr, item->addrlen);
 			ret = item->addrlen;
 		} else
 			ret = -EOVERFLOW;
-		cache_put(&item->h, &nfs_dns_resolve);
+		cache_put(&item->h, nn->nfs_dns_resolve);
 	} else if (ret == -ENOENT)
 		ret = -ESRCH;
 	return ret;
 }
 
+int nfs_dns_resolver_cache_init(struct net *net)
+{
+	int err = -ENOMEM;
+	struct nfs_net *nn = net_generic(net, nfs_net_id);
+	struct cache_detail *cd;
+	struct cache_head **tbl;
+
+	cd = kzalloc(sizeof(struct cache_detail), GFP_KERNEL);
+	if (cd == NULL)
+		goto err_cd;
+
+	tbl = kzalloc(NFS_DNS_HASHTBL_SIZE * sizeof(struct cache_head *),
+			GFP_KERNEL);
+	if (tbl == NULL)
+		goto err_tbl;
+
+	cd->owner = THIS_MODULE,
+	cd->hash_size = NFS_DNS_HASHTBL_SIZE,
+	cd->hash_table = tbl,
+	cd->name = "dns_resolve",
+	cd->cache_put = nfs_dns_ent_put,
+	cd->cache_upcall = nfs_dns_upcall,
+	cd->cache_parse = nfs_dns_parse,
+	cd->cache_show = nfs_dns_show,
+	cd->match = nfs_dns_match,
+	cd->init = nfs_dns_ent_init,
+	cd->update = nfs_dns_ent_update,
+	cd->alloc = nfs_dns_ent_alloc,
+
+	nfs_cache_init(cd);
+	err = nfs_cache_register_net(net, cd);
+	if (err)
+		goto err_reg;
+	nn->nfs_dns_resolve = cd;
+	return 0;
+
+err_reg:
+	nfs_cache_destroy(cd);
+	kfree(cd->hash_table);
+err_tbl:
+	kfree(cd);
+err_cd:
+	return err;
+}
+
+void nfs_dns_resolver_cache_destroy(struct net *net)
+{
+	struct nfs_net *nn = net_generic(net, nfs_net_id);
+	struct cache_detail *cd = nn->nfs_dns_resolve;
+
+	nfs_cache_unregister_net(net, cd);
+	nfs_cache_destroy(cd);
+	kfree(cd->hash_table);
+	kfree(cd);
+}
+
 int nfs_dns_resolver_init(void)
 {
-	int err;
-
-	nfs_cache_init(&nfs_dns_resolve);
-	err = nfs_cache_register_net(&init_net, &nfs_dns_resolve);
-	if (err) {
-		nfs_cache_destroy(&nfs_dns_resolve);
-		return err;
-	}
 	return 0;
 }
 
 void nfs_dns_resolver_destroy(void)
 {
-	nfs_cache_unregister_net(&init_net, &nfs_dns_resolve);
-	nfs_cache_destroy(&nfs_dns_resolve);
 }
-
 #endif

fs/nfs/dns_resolve.h

···
 
 static inline void nfs_dns_resolver_destroy(void)
 {}
+
+static inline int nfs_dns_resolver_cache_init(struct net *net)
+{
+	return 0;
+}
+
+static inline void nfs_dns_resolver_cache_destroy(struct net *net)
+{}
 #else
 extern int nfs_dns_resolver_init(void);
 extern void nfs_dns_resolver_destroy(void);
+extern int nfs_dns_resolver_cache_init(struct net *net);
+extern void nfs_dns_resolver_cache_destroy(struct net *net);
 #endif
 
-extern ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
-		struct sockaddr *sa, size_t salen);
+extern ssize_t nfs_dns_resolve_name(struct net *net, char *name,
+		size_t namelen,	struct sockaddr *sa, size_t salen);
 
 #endif

fs/nfs/inode.c

···
 #include "fscache.h"
 #include "dns_resolve.h"
 #include "pnfs.h"
+#include "netns.h"
 
 #define NFSDBG_FACILITY		NFSDBG_VFS
 
···
 	destroy_workqueue(wq);
 }
 
+int nfs_net_id;
+
+static int nfs_net_init(struct net *net)
+{
+	return nfs_dns_resolver_cache_init(net);
+}
+
+static void nfs_net_exit(struct net *net)
+{
+	nfs_dns_resolver_cache_destroy(net);
+}
+
+static struct pernet_operations nfs_net_ops = {
+	.init = nfs_net_init,
+	.exit = nfs_net_exit,
+	.id   = &nfs_net_id,
+	.size = sizeof(struct nfs_net),
+};
+
 /*
  * Initialize NFS
  */
···
 
 	err = nfs_idmap_init();
 	if (err < 0)
-		goto out9;
+		goto out10;
 
 	err = nfs_dns_resolver_init();
+	if (err < 0)
+		goto out9;
+
+	err = register_pernet_subsys(&nfs_net_ops);
 	if (err < 0)
 		goto out8;
 
···
 out6:
 	nfs_fscache_unregister();
 out7:
-	nfs_dns_resolver_destroy();
+	unregister_pernet_subsys(&nfs_net_ops);
 out8:
-	nfs_idmap_quit();
+	nfs_dns_resolver_destroy();
 out9:
+	nfs_idmap_quit();
+out10:
 	return err;
 }
 
···
 	nfs_destroy_inodecache();
 	nfs_destroy_nfspagecache();
 	nfs_fscache_unregister();
+	unregister_pernet_subsys(&nfs_net_ops);
 	nfs_dns_resolver_destroy();
 	nfs_idmap_quit();
 #ifdef CONFIG_PROC_FS

fs/nfs/netns.h

···
+#ifndef __NFS_NETNS_H__
+#define __NFS_NETNS_H__
+
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+
+struct nfs_net {
+	struct cache_detail *nfs_dns_resolve;
+};
+
+extern int nfs_net_id;
+
+#endif

fs/nfs/nfs4namespace.c

···
 }
 
 static size_t nfs_parse_server_name(char *string, size_t len,
-		struct sockaddr *sa, size_t salen)
+		struct sockaddr *sa, size_t salen, struct nfs_server *server)
 {
 	ssize_t ret;
 
 	ret = rpc_pton(string, len, sa, salen);
 	if (ret == 0) {
-		ret = nfs_dns_resolve_name(string, len, sa, salen);
+		ret = nfs_dns_resolve_name(server->client->cl_xprt->xprt_net,
+					   string, len, sa, salen);
 		if (ret < 0)
 			ret = 0;
 	}
···
 			continue;
 
 		mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
-				mountdata->addr, addr_bufsize);
+				mountdata->addr, addr_bufsize,
+				NFS_SB(mountdata->sb));
 		if (mountdata->addrlen == 0)
 			continue;