1 files changed, 38 insertions, 15 deletions

diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c
index 0004d18c40a..cc9f2546ea4 100644
--- a/fs/configfs/symlink.c
+++ b/fs/configfs/symlink.c
@@ -27,10 +27,14 @@
 #include <linux/fs.h>
 #include <linux/module.h>
 #include <linux/namei.h>
+#include <linux/slab.h>
 
 #include <linux/configfs.h>
 #include "configfs_internal.h"
 
+/* Protects attachments of new symlinks */
+DEFINE_MUTEX(configfs_symlink_mutex);
+
 static int item_depth(struct config_item * item)
 {
 	struct config_item * p = item;
@@ -73,11 +77,20 @@ static int create_link(struct config_item *parent_item,
 	struct configfs_symlink *sl;
 	int ret;
 
+	ret = -ENOENT;
+	if (!configfs_dirent_is_ready(target_sd))
+		goto out;
 	ret = -ENOMEM;
 	sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);
 	if (sl) {
 		sl->sl_target = config_item_get(item);
 		spin_lock(&configfs_dirent_lock);
+		if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
+			spin_unlock(&configfs_dirent_lock);
+			config_item_put(item);
+			kfree(sl);
+			return -ENOENT;
+		}
 		list_add(&sl->sl_list, &target_sd->s_links);
 		spin_unlock(&configfs_dirent_lock);
 		ret = configfs_create_link(sl, parent_item->ci_dentry,
@@ -91,25 +104,28 @@ static int create_link(struct config_item *parent_item,
 		}
 	}
 
+out:
 	return ret;
 }
 
 
-static int get_target(const char *symname, struct nameidata *nd,
-		      struct config_item **target)
+static int get_target(const char *symname, struct path *path,
+		      struct config_item **target, struct super_block *sb)
 {
 	int ret;
 
-	ret = path_lookup(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, nd);
+	ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path);
 	if (!ret) {
-		if (nd->path.dentry->d_sb == configfs_sb) {
-			*target = configfs_get_config_item(nd->path.dentry);
+		if (path->dentry->d_sb == sb) {
+			*target = configfs_get_config_item(path->dentry);
 			if (!*target) {
 				ret = -ENOENT;
-				path_put(&nd->path);
+				path_put(path);
 			}
-		} else
+		} else {
 			ret = -EPERM;
+			path_put(path);
+		}
 	}
 
 	return ret;
@@ -119,36 +135,45 @@ static int get_target(const char *symname, struct nameidata *nd,
 int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 {
 	int ret;
-	struct nameidata nd;
+	struct path path;
+	struct configfs_dirent *sd;
 	struct config_item *parent_item;
-	struct config_item *target_item;
+	struct config_item *target_item = NULL;
 	struct config_item_type *type;
 
-	ret = -EPERM;  /* What lack-of-symlink returns */
-	if (dentry->d_parent == configfs_sb->s_root)
+	sd = dentry->d_parent->d_fsdata;
+	/*
+	 * Fake invisibility if dir belongs to a group/default groups hierarchy
+	 * being attached
+	 */
+	ret = -ENOENT;
+	if (!configfs_dirent_is_ready(sd))
 		goto out;
 
 	parent_item = configfs_get_config_item(dentry->d_parent);
 	type = parent_item->ci_type;
 
+	ret = -EPERM;
 	if (!type || !type->ct_item_ops ||
 	    !type->ct_item_ops->allow_link)
 		goto out_put;
 
-	ret = get_target(symname, &nd, &target_item);
+	ret = get_target(symname, &path, &target_item, dentry->d_sb);
 	if (ret)
 		goto out_put;
 
 	ret = type->ct_item_ops->allow_link(parent_item, target_item);
 	if (!ret) {
+		mutex_lock(&configfs_symlink_mutex);
 		ret = create_link(parent_item, target_item, dentry);
+		mutex_unlock(&configfs_symlink_mutex);
 		if (ret && type->ct_item_ops->drop_link)
 			type->ct_item_ops->drop_link(parent_item,
 						     target_item);
 	}
 
 	config_item_put(target_item);
-	path_put(&nd.path);
+	path_put(&path);
 
 out_put:
 	config_item_put(parent_item);
@@ -169,8 +194,6 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry)
 	if (!(sd->s_type & CONFIGFS_ITEM_LINK))
 		goto out;
 
-	BUG_ON(dentry->d_parent == configfs_sb->s_root);
-
 	sl = sd->s_element;
 
 	parent_item = configfs_get_config_item(dentry->d_parent);