[PATCH 3/6] NFS: handle NFS caches dentries by network namespace aware routines

[Stanislav Kinsbursky <skinsbursky@parallels.com>]

This patch makes NFS caches PipeFS dentries allocated and destroyed in network
namespace context by PipeFS network namespace aware routines.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>

---
 fs/nfs/cache_lib.c   |   44 +++++++++++++++++++++++++++++++++++---------
 fs/nfs/cache_lib.h   |    4 ++--
 fs/nfs/dns_resolve.c |    4 ++--
 3 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/fs/nfs/cache_lib.c b/fs/nfs/cache_lib.c
index 9d79a2e..5dd017b 100644
--- a/fs/nfs/cache_lib.c
+++ b/fs/nfs/cache_lib.c
@@ -13,6 +13,7 @@
 #include <linux/slab.h>
 #include <linux/sunrpc/cache.h>
 #include <linux/sunrpc/rpc_pipe_fs.h>
+#include <net/net_namespace.h>
 
 #include "cache_lib.h"
 
@@ -111,20 +112,34 @@ int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq)
 	return 0;
 }
 
-int nfs_cache_register(struct cache_detail *cd)
+static int nfs_cache_register_sb(struct super_block *sb, struct cache_detail *cd)
+{
+	int ret;
+	struct dentry *dir;
+
+	dir = rpc_d_lookup_sb(sb, "cache");
+	BUG_ON(dir == NULL);
+	ret = sunrpc_cache_register_pipefs(dir, cd->name, 0600, cd);
+	dput(dir);
+	return ret;
+}
+
+int nfs_cache_register_net(struct net *net, struct cache_detail *cd)
 {
 	struct vfsmount *mnt;
-	struct path path;
+	struct super_block *pipefs_sb;
 	int ret;
 
 	mnt = rpc_get_mount();
 	if (IS_ERR(mnt))
 		return PTR_ERR(mnt);
-	ret = vfs_path_lookup(mnt->mnt_root, mnt, "/cache", 0, &path);
-	if (ret)
+	pipefs_sb = rpc_get_sb_net(net);
+	if (!pipefs_sb) {
+		ret = -ENOENT;
 		goto err;
-	ret = sunrpc_cache_register_pipefs(path.dentry, cd->name, 0600, cd);
-	path_put(&path);
+	}
+	ret = nfs_cache_register_sb(pipefs_sb, cd);
+	rpc_put_sb_net(net);
 	if (!ret)
 		return ret;
 err:
@@ -132,10 +147,21 @@ err:
 	return ret;
 }
 
-void nfs_cache_unregister(struct cache_detail *cd)
+static void nfs_cache_unregister_sb(struct super_block *sb, struct cache_detail *cd)
 {
-	sunrpc_cache_unregister_pipefs(cd);
-	sunrpc_destroy_cache_detail(cd);
+	if (cd->u.pipefs.dir)
+		sunrpc_cache_unregister_pipefs(cd);
+}
+
+void nfs_cache_unregister_net(struct net *net, struct cache_detail *cd)
+{
+	struct super_block *pipefs_sb;
+
+	pipefs_sb = rpc_get_sb_net(net);
+	if (pipefs_sb) {
+		nfs_cache_unregister_sb(pipefs_sb, cd);
+		rpc_put_sb_net(net);
+	}
 	rpc_put_mount();
 }
 
diff --git a/fs/nfs/cache_lib.h b/fs/nfs/cache_lib.h
index 815dd66..e0a6cc4 100644
--- a/fs/nfs/cache_lib.h
+++ b/fs/nfs/cache_lib.h
@@ -25,5 +25,5 @@ extern int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq);
 
 extern void nfs_cache_init(struct cache_detail *cd);
 extern void nfs_cache_destroy(struct cache_detail *cd);
-extern int nfs_cache_register(struct cache_detail *cd);
-extern void nfs_cache_unregister(struct cache_detail *cd);
+extern int nfs_cache_register_net(struct net *net, struct cache_detail *cd);
+extern void nfs_cache_unregister_net(struct net *net, struct cache_detail *cd);
diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c
index 619dea6..3cbf4b8 100644
--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -364,7 +364,7 @@ int nfs_dns_resolver_init(void)
 	int err;
 
 	nfs_cache_init(&nfs_dns_resolve);
-	err = nfs_cache_register(&nfs_dns_resolve);
+	err = nfs_cache_register_net(&init_net, &nfs_dns_resolve);
 	if (err) {
 		nfs_cache_destroy(&nfs_dns_resolve);
 		return err;
@@ -374,7 +374,7 @@ int nfs_dns_resolver_init(void)
 
 void nfs_dns_resolver_destroy(void)
 {
-	nfs_cache_unregister(&nfs_dns_resolve);
+	nfs_cache_unregister_net(&init_net, &nfs_dns_resolve);
 	nfs_cache_destroy(&nfs_dns_resolve);
 }