1 files changed, 92 insertions, 3 deletions

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 776137828dca..281c0c9bc39f 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -35,7 +35,7 @@ static const struct super_operations sysfs_ops = {
 struct sysfs_dirent sysfs_root = {
         .s_name         = "",
         .s_count        = ATOMIC_INIT(1),
-        .s_flags        = SYSFS_DIR,
+        .s_flags        = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
         .s_mode         = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
         .s_ino          = 1,
 };
@@ -72,18 +72,107 @@ static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
         return 0;
 }
 
+static int sysfs_test_super(struct super_block *sb, void *data)
+{
+        struct sysfs_super_info *sb_info = sysfs_info(sb);
+        struct sysfs_super_info *info = data;
+        enum kobj_ns_type type;
+        int found = 1;
+
+        for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
+                if (sb_info->ns[type] != info->ns[type])
+                        found = 0;
+        }
+        return found;
+}
+
+static int sysfs_set_super(struct super_block *sb, void *data)
+{
+        int error;
+        error = set_anon_super(sb, data);
+        if (!error)
+                sb->s_fs_info = data;
+        return error;
+}
+
 static int sysfs_get_sb(struct file_system_type *fs_type,
         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
-        return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
+        struct sysfs_super_info *info;
+        enum kobj_ns_type type;
+        struct super_block *sb;
+        int error;
+
+        error = -ENOMEM;
+        info = kzalloc(sizeof(*info), GFP_KERNEL);
+        if (!info)
+                goto out;
+
+        for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
+                info->ns[type] = kobj_ns_current(type);
+
+        sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info);
+        if (IS_ERR(sb) || sb->s_fs_info != info)
+                kfree(info);
+        if (IS_ERR(sb)) {
+                error = PTR_ERR(sb);
+                goto out;
+        }
+        if (!sb->s_root) {
+                sb->s_flags = flags;
+                error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
+                if (error) {
+                        deactivate_locked_super(sb);
+                        goto out;
+                }
+                sb->s_flags |= MS_ACTIVE;
+        }
+
+        simple_set_mnt(mnt, sb);
+        error = 0;
+out:
+        return error;
+}
+
+static void sysfs_kill_sb(struct super_block *sb)
+{
+        struct sysfs_super_info *info = sysfs_info(sb);
+
+        /* Remove the superblock from fs_supers/s_instances
+         * so we can't find it, before freeing sysfs_super_info.
+         */
+        kill_anon_super(sb);
+        kfree(info);
 }
 
 static struct file_system_type sysfs_fs_type = {
         .name           = "sysfs",
         .get_sb         = sysfs_get_sb,
-        .kill_sb        = kill_anon_super,
+        .kill_sb        = sysfs_kill_sb,
 };
 
+void sysfs_exit_ns(enum kobj_ns_type type, const void *ns)
+{
+        struct super_block *sb;
+
+        mutex_lock(&sysfs_mutex);
+        spin_lock(&sb_lock);
+        list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) {
+                struct sysfs_super_info *info = sysfs_info(sb);
+                /*
+                 * If we see a superblock on the fs_supers/s_instances
+                 * list the unmount has not completed and sb->s_fs_info
+                 * points to a valid struct sysfs_super_info.
+                 */
+                /* Ignore superblocks with the wrong ns */
+                if (info->ns[type] != ns)
+                        continue;
+                info->ns[type] = NULL;
+        }
+        spin_unlock(&sb_lock);
+        mutex_unlock(&sysfs_mutex);
+}
+
 int __init sysfs_init(void)
 {
         int err = -ENOMEM;