4 files changed, 44 insertions, 122 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 878ac3afe1b8..1dfb4aaf9446 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -111,6 +111,11 @@ static int sysfs_link_sibling(struct sysfs_dirent *sd)
 	/* add new node and rebalance the tree */
 	rb_link_node(&sd->s_rb, parent, node);
 	rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);
+
+	/* if @sd has ns tag, mark the parent to enable ns filtering */
+	if (sd->s_ns)
+		sd->s_parent->s_flags |= SYSFS_FLAG_HAS_NS;
+
 	return 0;
 }
 
@@ -130,6 +135,13 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
 		sd->s_parent->s_dir.subdirs--;
 
 	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
+
+	/*
+	 * Either all or none of the children have tags.  Clearing HAS_NS
+	 * when there's no child left is enough to keep the flag synced.
+	 */
+	if (RB_EMPTY_ROOT(&sd->s_parent->s_dir.children))
+		sd->s_parent->s_flags &= ~SYSFS_FLAG_HAS_NS;
 }
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -297,7 +309,6 @@ static int sysfs_dentry_delete(const struct dentry *dentry)
 static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct sysfs_dirent *sd;
-	int type;
 
 	if (flags & LOOKUP_RCU)
 		return -ECHILD;
@@ -318,13 +329,8 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_bad;
 
 	/* The sysfs dirent has been moved to a different namespace */
-	type = KOBJ_NS_TYPE_NONE;
-	if (sd->s_parent) {
-		type = sysfs_ns_type(sd->s_parent);
-		if (type != KOBJ_NS_TYPE_NONE &&
-				sysfs_info(dentry->d_sb)->ns[type] != sd->s_ns)
-			goto out_bad;
-	}
+	if (sd->s_ns && sd->s_ns != sysfs_info(dentry->d_sb)->ns)
+		goto out_bad;
 
 	mutex_unlock(&sysfs_mutex);
 out_valid:
@@ -445,13 +451,6 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
 	struct sysfs_inode_attrs *ps_iattr;
 	int ret;
 
-	if (!!sysfs_ns_type(acxt->parent_sd) != !!sd->s_ns) {
-		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-			sysfs_ns_type(acxt->parent_sd) ? "required" : "invalid",
-			acxt->parent_sd->s_name, sd->s_name);
-		return -EINVAL;
-	}
-
 	sd->s_hash = sysfs_name_hash(sd->s_ns, sd->s_name);
 	sd->s_parent = sysfs_get(acxt->parent_sd);
 
@@ -613,13 +612,6 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
 	struct rb_node *node = parent_sd->s_dir.children.rb_node;
 	unsigned int hash;
 
-	if (!!sysfs_ns_type(parent_sd) != !!ns) {
-		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-			sysfs_ns_type(parent_sd) ? "required" : "invalid",
-			parent_sd->s_name, name);
-		return NULL;
-	}
-
 	hash = sysfs_name_hash(ns, name);
 	while (node) {
 		struct sysfs_dirent *sd;
@@ -667,8 +659,7 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
 EXPORT_SYMBOL_GPL(sysfs_get_dirent);
 
 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
-	enum kobj_ns_type type, const void *ns, const char *name,
-	struct sysfs_dirent **p_sd)
+	const void *ns, const char *name, struct sysfs_dirent **p_sd)
 {
 	umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
 	struct sysfs_addrm_cxt acxt;
@@ -680,7 +671,6 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	if (!sd)
 		return -ENOMEM;
 
-	sd->s_flags |= (type << SYSFS_NS_TYPE_SHIFT);
 	sd->s_ns = ns;
 	sd->s_dir.kobj = kobj;
 
@@ -700,33 +690,7 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 int sysfs_create_subdir(struct kobject *kobj, const char *name,
 			struct sysfs_dirent **p_sd)
 {
-	return create_dir(kobj, kobj->sd,
-			  KOBJ_NS_TYPE_NONE, NULL, name, p_sd);
-}
-
-/**
- *	sysfs_read_ns_type: return associated ns_type
- *	@kobj: the kobject being queried
- *
- *	Each kobject can be tagged with exactly one namespace type
- *	(i.e. network or user).  Return the ns_type associated with
- *	this object if any
- */
-static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj)
-{
-	const struct kobj_ns_type_operations *ops;
-	enum kobj_ns_type type;
-
-	ops = kobj_child_ns_ops(kobj);
-	if (!ops)
-		return KOBJ_NS_TYPE_NONE;
-
-	type = ops->type;
-	BUG_ON(type <= KOBJ_NS_TYPE_NONE);
-	BUG_ON(type >= KOBJ_NS_TYPES);
-	BUG_ON(!kobj_ns_type_registered(type));
-
-	return type;
+	return create_dir(kobj, kobj->sd, NULL, name, p_sd);
 }
 
 /**
@@ -736,7 +700,6 @@ static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj)
  */
 int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 {
-	enum kobj_ns_type type;
 	struct sysfs_dirent *parent_sd, *sd;
 	int error = 0;
 
@@ -750,9 +713,7 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	if (!parent_sd)
 		return -ENOENT;
 
-	type = sysfs_read_ns_type(kobj);
-
-	error = create_dir(kobj, parent_sd, type, ns, kobject_name(kobj), &sd);
+	error = create_dir(kobj, parent_sd, ns, kobject_name(kobj), &sd);
 	if (!error)
 		kobj->sd = sd;
 	return error;
@@ -766,13 +727,12 @@ static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	struct sysfs_dirent *parent_sd = parent->d_fsdata;
 	struct sysfs_dirent *sd;
 	struct inode *inode;
-	enum kobj_ns_type type;
-	const void *ns;
+	const void *ns = NULL;
 
 	mutex_lock(&sysfs_mutex);
 
-	type = sysfs_ns_type(parent_sd);
-	ns = sysfs_info(dir->i_sb)->ns[type];
+	if (parent_sd->s_flags & SYSFS_FLAG_HAS_NS)
+		ns = sysfs_info(dir->i_sb)->ns;
 
 	sd = sysfs_find_dirent(parent_sd, ns, dentry->d_name.name);
 
@@ -995,15 +955,15 @@ static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 	struct dentry *dentry = file->f_path.dentry;
 	struct sysfs_dirent *parent_sd = dentry->d_fsdata;
 	struct sysfs_dirent *pos = file->private_data;
-	enum kobj_ns_type type;
-	const void *ns;
-
-	type = sysfs_ns_type(parent_sd);
-	ns = sysfs_info(dentry->d_sb)->ns[type];
+	const void *ns = NULL;
 
 	if (!dir_emit_dots(file, ctx))
 		return 0;
 	mutex_lock(&sysfs_mutex);
+
+	if (parent_sd->s_flags & SYSFS_FLAG_HAS_NS)
+		ns = sysfs_info(dentry->d_sb)->ns;
+
 	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
 	     pos;
 	     pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 834ec2cdb7a3..8c24bce2f4ae 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -36,7 +36,7 @@ static const struct super_operations sysfs_ops = {
 struct sysfs_dirent sysfs_root = {
 	.s_name		= "",
 	.s_count	= ATOMIC_INIT(1),
-	.s_flags	= SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
+	.s_flags	= SYSFS_DIR,
 	.s_mode		= S_IFDIR | S_IRUGO | S_IXUGO,
 	.s_ino		= 1,
 };
@@ -77,14 +77,8 @@ 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;
+	return sb_info->ns == info->ns;
 }
 
 static int sysfs_set_super(struct super_block *sb, void *data)
@@ -98,9 +92,7 @@ static int sysfs_set_super(struct super_block *sb, void *data)
 
 static void free_sysfs_super_info(struct sysfs_super_info *info)
 {
-	int type;
-	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
-		kobj_ns_drop(type, info->ns[type]);
+	kobj_ns_drop(KOBJ_NS_TYPE_NET, info->ns);
 	kfree(info);
 }
 
@@ -108,7 +100,6 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
 	struct sysfs_super_info *info;
-	enum kobj_ns_type type;
 	struct super_block *sb;
 	int error;
 
@@ -116,18 +107,15 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 		if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
 			return ERR_PTR(-EPERM);
 
-		for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
-			if (!kobj_ns_current_may_mount(type))
-				return ERR_PTR(-EPERM);
-		}
+		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
+			return ERR_PTR(-EPERM);
 	}
 
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
-		info->ns[type] = kobj_ns_grab_current(type);
+	info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
 
 	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
 	if (IS_ERR(sb) || sb->s_fs_info != info)
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 12d58ada3e6d..7d981ce2e87f 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -28,7 +28,6 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 	struct sysfs_dirent *target_sd = NULL;
 	struct sysfs_dirent *sd = NULL;
 	struct sysfs_addrm_cxt acxt;
-	enum kobj_ns_type ns_type;
 	int error;
 
 	BUG_ON(!name || !parent_sd);
@@ -50,29 +49,15 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 	if (!sd)
 		goto out_put;
 
-	ns_type = sysfs_ns_type(parent_sd);
-	if (ns_type)
-		sd->s_ns = target_sd->s_ns;
+	sd->s_ns = target_sd->s_ns;
 	sd->s_symlink.target_sd = target_sd;
 	target_sd = NULL;	/* reference is now owned by the symlink */
 
 	sysfs_addrm_start(&acxt, parent_sd);
-	/* Symlinks must be between directories with the same ns_type */
-	if (!ns_type ||
-	    (ns_type == sysfs_ns_type(sd->s_symlink.target_sd->s_parent))) {
-		if (warn)
-			error = sysfs_add_one(&acxt, sd);
-		else
-			error = __sysfs_add_one(&acxt, sd);
-	} else {
-		error = -EINVAL;
-		WARN(1, KERN_WARNING
-			"sysfs: symlink across ns_types %s/%s -> %s/%s\n",
-			parent_sd->s_name,
-			sd->s_name,
-			sd->s_symlink.target_sd->s_parent->s_name,
-			sd->s_symlink.target_sd->s_name);
-	}
+	if (warn)
+		error = sysfs_add_one(&acxt, sd);
+	else
+		error = __sysfs_add_one(&acxt, sd);
 	sysfs_addrm_finish(&acxt);
 
 	if (error)
@@ -156,7 +141,7 @@ void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
 {
 	const void *ns = NULL;
 	spin_lock(&sysfs_assoc_lock);
-	if (targ->sd && sysfs_ns_type(kobj->sd))
+	if (targ->sd)
 		ns = targ->sd->s_ns;
 	spin_unlock(&sysfs_assoc_lock);
 	sysfs_hash_and_remove(kobj->sd, ns, name);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index a96da2559db2..7664d1b3d594 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -93,11 +93,8 @@ struct sysfs_dirent {
 #define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
 #define SYSFS_ACTIVE_REF		(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR)
 
-/* identify any namespace tag on sysfs_dirents */
-#define SYSFS_NS_TYPE_MASK		0xf00
-#define SYSFS_NS_TYPE_SHIFT		8
-
-#define SYSFS_FLAG_MASK			~(SYSFS_NS_TYPE_MASK|SYSFS_TYPE_MASK)
+#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
+#define SYSFS_FLAG_HAS_NS		0x01000
 #define SYSFS_FLAG_REMOVED		0x02000
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
@@ -105,15 +102,6 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 	return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
-/*
- * Return any namespace tags on this dirent.
- * enum kobj_ns_type is defined in linux/kobject.h
- */
-static inline enum kobj_ns_type sysfs_ns_type(struct sysfs_dirent *sd)
-{
-	return (sd->s_flags & SYSFS_NS_TYPE_MASK) >> SYSFS_NS_TYPE_SHIFT;
-}
-
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 #define sysfs_dirent_init_lockdep(sd)				\
 do {								\
@@ -141,12 +129,13 @@ struct sysfs_addrm_cxt {
  */
 
 /*
- * Each sb is associated with a set of namespace tags (i.e.
- * the network namespace of the task which mounted this sysfs
- * instance).
+ * Each sb is associated with one namespace tag, currently the network
+ * namespace of the task which mounted this sysfs instance.  If multiple
+ * tags become necessary, make the following an array and compare
+ * sysfs_dirent tag against every entry.
  */
 struct sysfs_super_info {
-	void *ns[KOBJ_NS_TYPES];
+	void *ns;
 };
 #define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
 extern struct sysfs_dirent sysfs_root;