Revert "sysfs: drop kobj_ns_type handling"

This reverts commit cb26a311578e67769e92a39a0a63476533cb7e12.

It mysteriously causes NetworkManager to not find the wireless device
for me.  As far as I can tell, Tejun *meant* for this commit to not make
any semantic changes, but there clearly are some.  So revert it, taking
into account some of the calling convention changes that happened in
this area in subsequent commits.

Cc: Tejun Heo <tj@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 64 insertions, 24 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 08c66969d52a..5e73d6626e50 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -111,11 +111,6 @@ 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;
 }
 
@@ -135,13 +130,6 @@ 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;
 }
 
 /**
@@ -291,6 +279,7 @@ 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;
@@ -311,8 +300,13 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
                 goto out_bad;
 
         /* The sysfs dirent has been moved to a different namespace */
-        if (sd->s_ns && sd->s_ns != sysfs_info(dentry->d_sb)->ns)
-                goto out_bad;
+        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;
+        }
 
         mutex_unlock(&sysfs_mutex);
 out_valid:
@@ -432,6 +426,13 @@ 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(parent_sd) != !!sd->s_ns) {
+                WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
+                        sysfs_ns_type(parent_sd) ? "required" : "invalid",
+                        parent_sd->s_name, sd->s_name);
+                return -EINVAL;
+        }
+
         sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
         sd->s_parent = sysfs_get(parent_sd);
 
@@ -611,6 +612,13 @@ 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(name, ns);
         while (node) {
                 struct sysfs_dirent *sd;
@@ -659,6 +667,7 @@ struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
 EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
 
 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
+                      enum kobj_ns_type type,
                       const char *name, const void *ns,
                       struct sysfs_dirent **p_sd)
 {
@@ -672,6 +681,7 @@ 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;
 
@@ -691,7 +701,33 @@ 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, name, NULL, p_sd);
+        return create_dir(kobj, kobj->sd,
+                          KOBJ_NS_TYPE_NONE, name, NULL, 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;
 }
 
 /**
@@ -701,6 +737,7 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name,
  */
 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;
 
@@ -714,7 +751,9 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
         if (!parent_sd)
                 return -ENOENT;
 
-        error = create_dir(kobj, parent_sd, kobject_name(kobj), ns, &sd);
+        type = sysfs_read_ns_type(kobj);
+
+        error = create_dir(kobj, parent_sd, type, kobject_name(kobj), ns, &sd);
         if (!error)
                 kobj->sd = sd;
         return error;
@@ -728,12 +767,13 @@ 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;
-        const void *ns = NULL;
+        enum kobj_ns_type type;
+        const void *ns;
 
         mutex_lock(&sysfs_mutex);
 
-        if (parent_sd->s_flags & SYSFS_FLAG_HAS_NS)
-                ns = sysfs_info(dir->i_sb)->ns;
+        type = sysfs_ns_type(parent_sd);
+        ns = sysfs_info(dir->i_sb)->ns[type];
 
         sd = sysfs_find_dirent(parent_sd, dentry->d_name.name, ns);
 
@@ -1056,15 +1096,15 @@ 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;
-        const void *ns = NULL;
+        enum kobj_ns_type type;
+        const void *ns;
+
+        type = sysfs_ns_type(parent_sd);
+        ns = sysfs_info(dentry->d_sb)->ns[type];
 
         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)) {