[PATCH 3.4 61/88] nfsd: containerize NFSd filesystem

[Greg Kroah-Hartman]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>

note: this backport is just for the null pointer problem when
start nfsd in none init netns. The nfsd is still not containerized.

commit 11f779421a39b86da8a523d97e5fd3477878d44f upstream.

This patch makes NFSD file system superblock to be created per net.
This makes possible to get proper network namespace from superblock instead of
using hard-coded "init_net".

Note: NFSd fs super-block holds network namespace. This garantees, that
network namespace won't disappear from underneath of it.
This, obviously, means, that in case of kill of a container's "init" (which is not a mount
namespace, but network namespace creator) netowrk namespace won't be
destroyed.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
[wengmeiling: backport to 3.4:
 - export cache not per netns
 - NFSD service structure not per netns]
Signed-off-by: Weng Meiling <wengmeiling.weng@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/nfsd/nfsctl.c |   30 +++++++++++++++++++++++-------
 fs/nfsd/nfssvc.c |    2 +-
 2 files changed, 24 insertions(+), 8 deletions(-)

--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -213,6 +213,7 @@ static ssize_t write_unlock_ip(struct fi
 	struct sockaddr *sap = (struct sockaddr *)&address;
 	size_t salen = sizeof(address);
 	char *fo_path;
+	struct net *net = file->f_dentry->d_sb->s_fs_info;
 
 	/* sanity check */
 	if (size == 0)
@@ -225,7 +226,7 @@ static ssize_t write_unlock_ip(struct fi
 	if (qword_get(&buf, fo_path, size) < 0)
 		return -EINVAL;
 
-	if (rpc_pton(&init_net, fo_path, size, sap, salen) == 0)
+	if (rpc_pton(net, fo_path, size, sap, salen) == 0)
 		return -EINVAL;
 
 	return nlmsvc_unlock_all_by_ip(sap);
@@ -389,7 +390,7 @@ static ssize_t write_threads(struct file
 {
 	char *mesg = buf;
 	int rv;
-	struct net *net = &init_net;
+	struct net *net = file->f_dentry->d_sb->s_fs_info;
 
 	if (size > 0) {
 		int newthreads;
@@ -440,7 +441,7 @@ static ssize_t write_pool_threads(struct
 	int len;
 	int npools;
 	int *nthreads;
-	struct net *net = &init_net;
+	struct net *net = file->f_dentry->d_sb->s_fs_info;
 
 	mutex_lock(&nfsd_mutex);
 	npools = nfsd_nrpools();
@@ -857,7 +858,7 @@ static ssize_t __write_ports(struct file
 static ssize_t write_ports(struct file *file, char *buf, size_t size)
 {
 	ssize_t rv;
-	struct net *net = &init_net;
+	struct net *net = file->f_dentry->d_sb->s_fs_info;
 
 	mutex_lock(&nfsd_mutex);
 	rv = __write_ports(file, buf, size, net);
@@ -1095,20 +1096,35 @@ static int nfsd_fill_super(struct super_
 #endif
 		/* last one */ {""}
 	};
-	return simple_fill_super(sb, 0x6e667364, nfsd_files);
+	struct net *net = data;
+	int ret;
+
+	ret = simple_fill_super(sb, 0x6e667364, nfsd_files);
+	if (ret)
+		return ret;
+	sb->s_fs_info = get_net(net);
+	return 0;
 }
 
 static struct dentry *nfsd_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
-	return mount_single(fs_type, flags, data, nfsd_fill_super);
+	return mount_ns(fs_type, flags, current->nsproxy->net_ns, nfsd_fill_super);
+}
+
+static void nfsd_umount(struct super_block *sb)
+{
+	struct net *net = sb->s_fs_info;
+
+	kill_litter_super(sb);
+	put_net(net);
 }
 
 static struct file_system_type nfsd_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "nfsd",
 	.mount		= nfsd_mount,
-	.kill_sb	= kill_litter_super,
+	.kill_sb	= nfsd_umount,
 };
 
 #ifdef CONFIG_PROC_FS
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -670,7 +670,7 @@ int nfsd_pool_stats_open(struct inode *i
 int nfsd_pool_stats_release(struct inode *inode, struct file *file)
 {
 	int ret = seq_release(inode, file);
-	struct net *net = &init_net;
+	struct net *net = inode->i_sb->s_fs_info;
 
 	mutex_lock(&nfsd_mutex);
 	/* this function really, really should have been called svc_put() */


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