1 files changed, 56 insertions, 66 deletions

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index cf7b7e1d5bd7..d1f9d2632202 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-/* -*- mode: c; c-basic-offset: 8; -*-
- * vim: noexpandtab sw=8 ts=8 sts=0:
- *
+/*
  * dir.c - Operations for configfs directories.
  *
  * Based on sysfs:
@@ -36,6 +34,14 @@
  */
 DEFINE_SPINLOCK(configfs_dirent_lock);
 
+/*
+ * All of link_obj/unlink_obj/link_group/unlink_group require that
+ * subsys->su_mutex is held.
+ * But parent configfs_subsystem is NULL when config_item is root.
+ * Use this mutex when config_item is root.
+ */
+static DEFINE_MUTEX(configfs_subsystem_mutex);
+
 static void configfs_d_iput(struct dentry * dentry,
 			    struct inode * inode)
 {
@@ -47,7 +53,7 @@ static void configfs_d_iput(struct dentry * dentry,
 		/*
 		 * Set sd->s_dentry to null only when this dentry is the one
 		 * that is going to be killed.  Otherwise configfs_d_iput may
-		 * run just after configfs_attach_attr and set sd->s_dentry to
+		 * run just after configfs_lookup and set sd->s_dentry to
 		 * NULL even it's still in use.
 		 */
 		if (sd->s_dentry == dentry)
@@ -267,6 +273,7 @@ static void configfs_remove_dirent(struct dentry *dentry)
  *	configfs_create_dir - create a directory for an config_item.
  *	@item:		config_itemwe're creating directory for.
  *	@dentry:	config_item's dentry.
+ *	@frag:		config_item's fragment.
  *
  *	Note: user-created entries won't be allowed under this new directory
  *	until it is validated by configfs_dir_set_ready()
@@ -418,44 +425,16 @@ static void configfs_remove_dir(struct config_item * item)
 	dput(dentry);
 }
 
-
-/* attaches attribute's configfs_dirent to the dentry corresponding to the
- * attribute file
- */
-static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
-{
-	struct configfs_attribute * attr = sd->s_element;
-	struct inode *inode;
-
-	spin_lock(&configfs_dirent_lock);
-	dentry->d_fsdata = configfs_get(sd);
-	sd->s_dentry = dentry;
-	spin_unlock(&configfs_dirent_lock);
-
-	inode = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG);
-	if (IS_ERR(inode)) {
-		configfs_put(sd);
-		return PTR_ERR(inode);
-	}
-	if (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) {
-		inode->i_size = 0;
-		inode->i_fop = &configfs_bin_file_operations;
-	} else {
-		inode->i_size = PAGE_SIZE;
-		inode->i_fop = &configfs_file_operations;
-	}
-	d_add(dentry, inode);
-	return 0;
-}
-
 static struct dentry * configfs_lookup(struct inode *dir,
 				       struct dentry *dentry,
 				       unsigned int flags)
 {
 	struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 	struct configfs_dirent * sd;
-	int found = 0;
-	int err;
+	struct inode *inode = NULL;
+
+	if (dentry->d_name.len > NAME_MAX)
+		return ERR_PTR(-ENAMETOOLONG);
 
 	/*
 	 * Fake invisibility if dir belongs to a group/default groups hierarchy
@@ -465,36 +444,39 @@ static struct dentry * configfs_lookup(struct inode *dir,
 	 * not complete their initialization, since the dentries of the
 	 * attributes won't be instantiated.
 	 */
-	err = -ENOENT;
 	if (!configfs_dirent_is_ready(parent_sd))
-		goto out;
+		return ERR_PTR(-ENOENT);
 
+	spin_lock(&configfs_dirent_lock);
 	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
-		if (sd->s_type & CONFIGFS_NOT_PINNED) {
-			const unsigned char * name = configfs_get_name(sd);
+		if ((sd->s_type & CONFIGFS_NOT_PINNED) &&
+		    !strcmp(configfs_get_name(sd), dentry->d_name.name)) {
+			struct configfs_attribute *attr = sd->s_element;
+			umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
 
-			if (strcmp(name, dentry->d_name.name))
-				continue;
+			dentry->d_fsdata = configfs_get(sd);
+			sd->s_dentry = dentry;
+			spin_unlock(&configfs_dirent_lock);
 
-			found = 1;
-			err = configfs_attach_attr(sd, dentry);
-			break;
+			inode = configfs_create(dentry, mode);
+			if (IS_ERR(inode)) {
+				configfs_put(sd);
+				return ERR_CAST(inode);
+			}
+			if (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) {
+				inode->i_size = 0;
+				inode->i_fop = &configfs_bin_file_operations;
+			} else {
+				inode->i_size = PAGE_SIZE;
+				inode->i_fop = &configfs_file_operations;
+			}
+			goto done;
 		}
 	}
-
-	if (!found) {
-		/*
-		 * If it doesn't exist and it isn't a NOT_PINNED item,
-		 * it must be negative.
-		 */
-		if (dentry->d_name.len > NAME_MAX)
-			return ERR_PTR(-ENAMETOOLONG);
-		d_add(dentry, NULL);
-		return NULL;
-	}
-
-out:
-	return ERR_PTR(err);
+	spin_unlock(&configfs_dirent_lock);
+done:
+	d_add(dentry, inode);
+	return NULL;
 }
 
 /*
@@ -1168,7 +1150,7 @@ EXPORT_SYMBOL(configfs_depend_item);
 
 /*
  * Release the dependent linkage.  This is much simpler than
- * configfs_depend_item() because we know that that the client driver is
+ * configfs_depend_item() because we know that the client driver is
  * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
  */
 void configfs_undepend_item(struct config_item *target)
@@ -1267,7 +1249,8 @@ out_root_unlock:
 }
 EXPORT_SYMBOL(configfs_depend_item_unlocked);
 
-static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int configfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+			  struct dentry *dentry, umode_t mode)
 {
 	int ret = 0;
 	int module_got = 0;
@@ -1519,6 +1502,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 		spin_lock(&configfs_dirent_lock);
 		configfs_detach_rollback(dentry);
 		spin_unlock(&configfs_dirent_lock);
+		config_item_put(parent_item);
 		return -EINTR;
 	}
 	frag->frag_dead = true;
@@ -1687,11 +1671,11 @@ static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
 	switch (whence) {
 		case 1:
 			offset += file->f_pos;
-			/* fall through */
+			fallthrough;
 		case 0:
 			if (offset >= 0)
 				break;
-			/* fall through */
+			fallthrough;
 		default:
 			return -EINVAL;
 	}
@@ -1804,8 +1788,8 @@ void configfs_unregister_group(struct config_group *group)
 	configfs_detach_group(&group->cg_item);
 	d_inode(dentry)->i_flags |= S_DEAD;
 	dont_mount(dentry);
+	d_drop(dentry);
 	fsnotify_rmdir(d_inode(parent), dentry);
-	d_delete(dentry);
 	inode_unlock(d_inode(parent));
 
 	dput(dentry);
@@ -1883,7 +1867,9 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
 		group->cg_item.ci_name = group->cg_item.ci_namebuf;
 
 	sd = root->d_fsdata;
+	mutex_lock(&configfs_subsystem_mutex);
 	link_group(to_config_group(sd->s_element), group);
+	mutex_unlock(&configfs_subsystem_mutex);
 
 	inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
 
@@ -1908,7 +1894,9 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
 	inode_unlock(d_inode(root));
 
 	if (err) {
+		mutex_lock(&configfs_subsystem_mutex);
 		unlink_group(group);
+		mutex_unlock(&configfs_subsystem_mutex);
 		configfs_release_fs();
 	}
 	put_fragment(frag);
@@ -1946,16 +1934,18 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
 	configfs_detach_group(&group->cg_item);
 	d_inode(dentry)->i_flags |= S_DEAD;
 	dont_mount(dentry);
-	fsnotify_rmdir(d_inode(root), dentry);
 	inode_unlock(d_inode(dentry));
 
-	d_delete(dentry);
+	d_drop(dentry);
+	fsnotify_rmdir(d_inode(root), dentry);
 
 	inode_unlock(d_inode(root));
 
 	dput(dentry);
 
+	mutex_lock(&configfs_subsystem_mutex);
 	unlink_group(group);
+	mutex_unlock(&configfs_subsystem_mutex);
 	configfs_release_fs();
 }