[PATCH v3, RESEND 10/16] nfs: per-rpc_pipefs dns cache

["Kirill A. Shutemov" <kas@openvz.org>]

Lazy initialization of dns cache: on first call nfs_dns_resolve_name().
Every rpc_pipefs has separate dns cache now.

Signed-off-by: Kirill A. Shutemov <kas@openvz.org>
Reviewed-by: Rob Landley <rlandley@parallels.com>
---
 fs/nfs/cache_lib.c     |   17 ++-----
 fs/nfs/cache_lib.h     |    3 +-
 fs/nfs/dns_resolve.c   |  137 +++++++++++++++++++++++++++++++++++++-----------
 fs/nfs/dns_resolve.h   |   15 +-----
 fs/nfs/inode.c         |    9 +---
 fs/nfs/nfs4namespace.c |    4 +-
 6 files changed, 117 insertions(+), 68 deletions(-)

diff --git a/fs/nfs/cache_lib.c b/fs/nfs/cache_lib.c
index 0944d4e..9b99d9e 100644
--- a/fs/nfs/cache_lib.c
+++ b/fs/nfs/cache_lib.c
@@ -12,7 +12,6 @@
 #include <linux/namei.h>
 #include <linux/slab.h>
 #include <linux/sunrpc/cache.h>
-#include <linux/sunrpc/rpc_pipe_fs.h>
 
 #include "cache_lib.h"
 
@@ -111,25 +110,17 @@ int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq)
 	return 0;
 }
 
-int nfs_cache_register(struct cache_detail *cd)
+int nfs_cache_register(struct cache_detail *cd, struct vfsmount *rpcmount)
 {
 	struct nameidata nd;
-	struct vfsmount *mnt;
 	int ret;
 
-	mnt = mntget(init_rpc_pipefs);
-	if (IS_ERR(mnt))
-		return PTR_ERR(mnt);
-	ret = vfs_path_lookup(mnt->mnt_root, mnt, "/cache", 0, &nd);
+	ret = vfs_path_lookup(rpcmount->mnt_root, rpcmount, "/cache", 0, &nd);
 	if (ret)
-		goto err;
-	ret = sunrpc_cache_register_pipefs(mnt, nd.path.dentry,
+		return ret;
+	ret = sunrpc_cache_register_pipefs(rpcmount, nd.path.dentry,
 			cd->name, 0600, cd);
 	path_put(&nd.path);
-	if (!ret)
-		return ret;
-err:
-	mntput(mnt);
 	return ret;
 }
 
diff --git a/fs/nfs/cache_lib.h b/fs/nfs/cache_lib.h
index 76f856e..1d4a0a5 100644
--- a/fs/nfs/cache_lib.h
+++ b/fs/nfs/cache_lib.h
@@ -23,5 +23,6 @@ extern struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void);
 extern void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq);
 extern int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq);
 
-extern int nfs_cache_register(struct cache_detail *cd);
+extern int nfs_cache_register(struct cache_detail *cd,
+		struct vfsmount *rpcmount);
 extern void nfs_cache_unregister(struct cache_detail *cd);
diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c
index a6e711a..a832e64 100644
--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -12,7 +12,7 @@
 #include <linux/dns_resolver.h>
 
 ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
-		struct sockaddr *sa, size_t salen)
+		struct sockaddr *sa, size_t salen, struct vfsmount *rpcmount)
 {
 	ssize_t ret;
 	char *ip_addr = NULL;
@@ -37,9 +37,11 @@ ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
 #include <linux/socket.h>
 #include <linux/seq_file.h>
 #include <linux/inet.h>
+#include <linux/mount.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/cache.h>
 #include <linux/sunrpc/svcauth.h>
+#include <linux/sunrpc/rpc_pipe_fs.h>
 
 #include "dns_resolve.h"
 #include "cache_lib.h"
@@ -47,7 +49,13 @@ ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
 #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];
+static DEFINE_SPINLOCK(nfs_dns_resolve_lock);
+static LIST_HEAD(nfs_dns_resolve_list);
+
+struct nfs_dns_resolve_list {
+	struct list_head list;
+	struct cache_detail *cd;
+};
 
 struct nfs_dns_ent {
 	struct cache_head h;
@@ -259,21 +267,6 @@ 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,
@@ -336,37 +329,119 @@ out:
 	return ret;
 }
 
+static struct cache_detail *nfs_alloc_dns_resolve(void)
+{
+	struct cache_detail *dns_resolve;
+	struct cache_head **hash_table;
+
+	dns_resolve = kmalloc(sizeof(*dns_resolve), GFP_KERNEL);
+	if (!dns_resolve)
+		return NULL;
+
+	hash_table = kmalloc(sizeof(*hash_table) * NFS_DNS_HASHTBL_SIZE,
+			GFP_KERNEL);
+	if (!hash_table) {
+		kfree(dns_resolve);
+		return NULL;
+	}
+
+	dns_resolve->owner = THIS_MODULE;
+	dns_resolve->hash_size = NFS_DNS_HASHTBL_SIZE;
+	dns_resolve->hash_table = hash_table;
+	dns_resolve->name = "dns_resolve";
+	dns_resolve->cache_put = nfs_dns_ent_put;
+	dns_resolve->cache_upcall = nfs_dns_upcall;
+	dns_resolve->cache_parse = nfs_dns_parse;
+	dns_resolve->cache_show = nfs_dns_show;
+	dns_resolve->match = nfs_dns_match;
+	dns_resolve->init = nfs_dns_ent_init;
+	dns_resolve->update = nfs_dns_ent_update;
+	dns_resolve->alloc = nfs_dns_ent_alloc;
+
+	return dns_resolve;
+}
+
+static void nfs_free_dns_resolve(struct cache_detail *dns_resolve)
+{
+	kfree(dns_resolve->hash_table);
+	kfree(dns_resolve);
+}
+
+static struct cache_detail *nfs_get_dns_resolve(struct vfsmount *rpcmount)
+{
+	struct nfs_dns_resolve_list *dns_resolve;
+	int error = 0;
+
+	spin_lock(&nfs_dns_resolve_lock);
+	list_for_each_entry(dns_resolve, &nfs_dns_resolve_list, list) {
+		if (dns_resolve->cd->u.pipefs.mnt->mnt_sb != rpcmount->mnt_sb)
+			continue;
+
+		spin_unlock(&nfs_dns_resolve_lock);
+		return dns_resolve->cd;
+	}
+
+	dns_resolve = kmalloc(sizeof(*dns_resolve), GFP_KERNEL);
+	if (dns_resolve)
+		dns_resolve->cd = nfs_alloc_dns_resolve();
+	if (!dns_resolve || !dns_resolve->cd) {
+		error = -ENOMEM;
+		goto err;
+	}
+
+	error = nfs_cache_register(dns_resolve->cd, rpcmount);
+	if (error)
+		goto err;
+
+	INIT_LIST_HEAD(&dns_resolve->list);
+	list_add(&dns_resolve->list, &nfs_dns_resolve_list);
+	spin_unlock(&nfs_dns_resolve_lock);
+
+	return dns_resolve->cd;
+err:
+	spin_unlock(&nfs_dns_resolve_lock);
+	if (dns_resolve)
+		kfree(dns_resolve->cd);
+	kfree(dns_resolve);
+	return dns_resolve->cd;
+}
+
+static void nfs_dns_resolver_destroy(void *data)
+{
+	struct nfs_dns_resolve_list *dns_resolve = data;
+
+	spin_lock(&nfs_dns_resolve_lock);
+	nfs_cache_unregister(dns_resolve->cd);
+	nfs_free_dns_resolve(dns_resolve->cd);
+	list_del(&dns_resolve->list);
+	kfree(dns_resolve);
+	spin_unlock(&nfs_dns_resolve_lock);
+}
+
 ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
-		struct sockaddr *sa, size_t salen)
+		struct sockaddr *sa, size_t salen, struct vfsmount *rpcmount)
 {
 	struct nfs_dns_ent key = {
 		.hostname = name,
 		.namelen = namelen,
 	};
+	struct cache_detail *dns_resolve;
 	struct nfs_dns_ent *item = NULL;
 	ssize_t ret;
 
-	ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item);
+	dns_resolve = nfs_get_dns_resolve(rpcmount);
+	ret = do_cache_lookup_wait(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, dns_resolve);
+		rpc_pipefs_add_destroy_cb(rpcmount->mnt_sb,
+				nfs_dns_resolver_destroy, dns_resolve);
 	} else if (ret == -ENOENT)
 		ret = -ESRCH;
 	return ret;
 }
-
-int nfs_dns_resolver_init(void)
-{
-	return nfs_cache_register(&nfs_dns_resolve);
-}
-
-void nfs_dns_resolver_destroy(void)
-{
-	nfs_cache_unregister(&nfs_dns_resolve);
-}
-
 #endif
diff --git a/fs/nfs/dns_resolve.h b/fs/nfs/dns_resolve.h
index 199bb55..74ade60 100644
--- a/fs/nfs/dns_resolve.h
+++ b/fs/nfs/dns_resolve.h
@@ -7,20 +7,7 @@
 #define NFS_DNS_HOSTNAME_MAXLEN	(128)
 
 
-#ifdef CONFIG_NFS_USE_KERNEL_DNS
-static inline int nfs_dns_resolver_init(void)
-{
-	return 0;
-}
-
-static inline void nfs_dns_resolver_destroy(void)
-{}
-#else
-extern int nfs_dns_resolver_init(void);
-extern void nfs_dns_resolver_destroy(void);
-#endif
-
 extern ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
-		struct sockaddr *sa, size_t salen);
+		struct sockaddr *sa, size_t salen, struct vfsmount *rpcmount);
 
 #endif
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 1cc600e..1c3be51 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1543,10 +1543,6 @@ static int __init init_nfs_fs(void)
 
 	err = nfs_idmap_init();
 	if (err < 0)
-		goto out9;
-
-	err = nfs_dns_resolver_init();
-	if (err < 0)
 		goto out8;
 
 	err = nfs_fscache_register();
@@ -1607,10 +1603,8 @@ out5:
 out6:
 	nfs_fscache_unregister();
 out7:
-	nfs_dns_resolver_destroy();
-out8:
 	nfs_idmap_quit();
-out9:
+out8:
 	return err;
 }
 
@@ -1622,7 +1616,6 @@ static void __exit exit_nfs_fs(void)
 	nfs_destroy_inodecache();
 	nfs_destroy_nfspagecache();
 	nfs_fscache_unregister();
-	nfs_dns_resolver_destroy();
 	nfs_idmap_quit();
 #ifdef CONFIG_PROC_FS
 	rpc_proc_unregister("nfs");
diff --git a/fs/nfs/nfs4namespace.c b/fs/nfs/nfs4namespace.c
index 3c2a172..7a61fdb 100644
--- a/fs/nfs/nfs4namespace.c
+++ b/fs/nfs/nfs4namespace.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/rpc_pipe_fs.h>
 #include <linux/vfs.h>
 #include <linux/inet.h>
 #include "internal.h"
@@ -104,7 +105,8 @@ static size_t nfs_parse_server_name(char *string, size_t len,
 
 	ret = rpc_pton(string, len, sa, salen);
 	if (ret == 0) {
-		ret = nfs_dns_resolve_name(string, len, sa, salen);
+		ret = nfs_dns_resolve_name(string, len, sa, salen,
+				init_rpc_pipefs);
 		if (ret < 0)
 			ret = 0;
 	}
-- 
1.7.4