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

5 files changed, 123 insertions, 41 deletions

diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c
index 3cbf4b88f827..9aea78ab86ac 100644
--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -11,7 +11,7 @@
 #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;
@@ -43,12 +43,11 @@ ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
 
 #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;
 
@@ -259,21 +258,6 @@ out:
         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,
@@ -336,8 +320,8 @@ out:
         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,
@@ -345,37 +329,83 @@ ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
         };
         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_init(void)
+int nfs_dns_resolver_cache_init(struct net *net)
 {
-        int err;
+        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;
 
-        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;
-        }
+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)
+{
         return 0;
 }
 
 void nfs_dns_resolver_destroy(void)
 {
-        nfs_cache_unregister_net(&init_net, &nfs_dns_resolve);
-        nfs_cache_destroy(&nfs_dns_resolve);
 }
-
 #endif
diff --git a/fs/nfs/dns_resolve.h b/fs/nfs/dns_resolve.h
index 199bb5543a91..2e4f596d2923 100644
--- a/fs/nfs/dns_resolve.h
+++ b/fs/nfs/dns_resolve.h
@@ -15,12 +15,22 @@ static inline int nfs_dns_resolver_init(void)
 
 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
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index f649fba8c384..0335f6e4ff7e 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -51,6 +51,7 @@
 #include "fscache.h"
 #include "dns_resolve.h"
 #include "pnfs.h"
+#include "netns.h"
 
 #define NFSDBG_FACILITY         NFSDBG_VFS
 
@@ -1552,6 +1553,25 @@ static void nfsiod_stop(void)
         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
  */
@@ -1561,10 +1581,14 @@ static int __init init_nfs_fs(void)
 
         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;
 
         err = nfs_fscache_register();
@@ -1625,10 +1649,12 @@ out5:
 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;
 }
 
@@ -1640,6 +1666,7 @@ static void __exit exit_nfs_fs(void)
         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
diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h
new file mode 100644
index 000000000000..8c1f130d6ca2
--- /dev/null
+++ b/fs/nfs/netns.h
@@ -0,0 +1,13 @@
+#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
diff --git a/fs/nfs/nfs4namespace.c b/fs/nfs/nfs4namespace.c
index bb80c49b6533..919a36935924 100644
--- a/fs/nfs/nfs4namespace.c
+++ b/fs/nfs/nfs4namespace.c
@@ -94,13 +94,14 @@ static int nfs4_validate_fspath(struct dentry *dentry,
 }
 
 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;
         }
@@ -137,7 +138,8 @@ static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
                         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;