--- a/fs/mini_fo/aux.c
+++ b/fs/mini_fo/aux.c
@@ -86,8 +86,10 @@ int get_neg_sto_dentry(dentry_t *dentry)
 	len = dentry->d_name.len;
 	name = dentry->d_name.name;
 
+	mutex_lock(&dtohd2(dentry->d_parent)->d_inode->i_mutex);
 	dtohd2(dentry) =
 		lookup_one_len(name, dtohd2(dentry->d_parent), len);
+	mutex_unlock(&dtohd2(dentry->d_parent)->d_inode->i_mutex);
 
  out:
 	return err;
@@ -426,7 +428,9 @@ int build_sto_structure(dentry_t *dir, d
 		const unsigned char *name;
 		len = dtohd(dentry)->d_name.len;
 		name = dtohd(dentry)->d_name.name;
+		mutex_lock(&dtohd2(dir)->d_inode->i_mutex);
 		hidden_sto_dentry = lookup_one_len(name, dtohd2(dir), len);
+		mutex_unlock(&dtohd2(dir)->d_inode->i_mutex);
 		dtohd2(dentry) = hidden_sto_dentry;
 	}
 
--- a/fs/mini_fo/inode.c
+++ b/fs/mini_fo/inode.c
@@ -113,17 +113,23 @@ mini_fo_lookup(inode_t *dir, dentry_t *d
 		hidden_dir_dentry = hidden_dentry->d_parent;
 		kfree(bpath);
 	}
-	else if(hidden_dir_dentry && hidden_dir_dentry->d_inode)
+	else if(hidden_dir_dentry && hidden_dir_dentry->d_inode) {
+		mutex_lock(&hidden_dir_dentry->d_inode->i_mutex);
 		hidden_dentry =
 			lookup_one_len(name, hidden_dir_dentry, namelen);
-	else
+		mutex_unlock(&hidden_dir_dentry->d_inode->i_mutex);
+	} else {
 		hidden_dentry = NULL;
+	}
 
-	if(hidden_sto_dir_dentry && hidden_sto_dir_dentry->d_inode)
+	if(hidden_sto_dir_dentry && hidden_sto_dir_dentry->d_inode) {
+		mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
 		hidden_sto_dentry =
 			lookup_one_len(name, hidden_sto_dir_dentry, namelen);
-	else
+		mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+	} else {
 		hidden_sto_dentry =  NULL;
+	}
 
 	/* catch error in lookup */
 	if (IS_ERR(hidden_dentry) || IS_ERR(hidden_sto_dentry)) {
@@ -553,9 +559,11 @@ mini_fo_rmdir(inode_t *dir, dentry_t *de
 #endif
 
 		/* Delete an old WOL file contained in the storage dir */
+		mutex_lock(&hidden_sto_dentry->d_inode->i_mutex);
 		meta_dentry = lookup_one_len(META_FILENAME,
 					     hidden_sto_dentry,
 					     strlen(META_FILENAME));
+		mutex_unlock(&hidden_sto_dentry->d_inode->i_mutex);
 		if(meta_dentry->d_inode) {
 			err = vfs_unlink(hidden_sto_dentry->d_inode, meta_dentry);
 			dput(meta_dentry);
@@ -643,9 +651,11 @@ mini_fo_rmdir(inode_t *dir, dentry_t *de
 #endif
 
 		/* Delete an old WOL file contained in the storage dir */
+		mutex_lock(&hidden_sto_dentry->d_inode->i_mutex);
 		meta_dentry = lookup_one_len(META_FILENAME,
 					     hidden_sto_dentry,
 					     strlen(META_FILENAME));
+		mutex_unlock(&hidden_sto_dentry->d_inode->i_mutex);
 		if(meta_dentry->d_inode) {
 			/* is this necessary? dget(meta_dentry); */
 			err = vfs_unlink(hidden_sto_dentry->d_inode,
@@ -688,9 +698,11 @@ mini_fo_rmdir(inode_t *dir, dentry_t *de
 #endif
 
 		/* Delete an old WOL file contained in the storage dir */
+		mutex_lock(&hidden_sto_dentry->d_inode->i_mutex);
 		meta_dentry = lookup_one_len(META_FILENAME,
 					     hidden_sto_dentry,
 					     strlen(META_FILENAME));
+		mutex_unlock(&hidden_sto_dentry->d_inode->i_mutex);
 		if(meta_dentry->d_inode) {
 			/* is this necessary? dget(meta_dentry); */
 			err = vfs_unlink(hidden_sto_dentry->d_inode,
--- a/fs/mini_fo/meta.c
+++ b/fs/mini_fo/meta.c
@@ -43,9 +43,11 @@ int meta_build_lists(dentry_t *dentry)
 
   	/* might there be a META-file? */
 	if(dtohd2(dentry) && dtohd2(dentry)->d_inode) {
+		mutex_lock(&dtohd2(dentry)->d_inode->i_mutex);
 		meta_dentry = lookup_one_len(META_FILENAME,
 					     dtohd2(dentry),
 					     strlen(META_FILENAME));
+		mutex_unlock(&dtohd2(dentry)->d_inode->i_mutex);
 		if(!meta_dentry->d_inode) {
 			dput(meta_dentry);
 			goto out_ok;
@@ -426,8 +428,11 @@ int meta_write_d_entry(dentry_t *dentry,
 			goto out;
                 }
         }
+
+	mutex_lock(&dtohd2(dentry)->d_inode->i_mutex);
 	meta_dentry = lookup_one_len(META_FILENAME,
 				     dtohd2(dentry), strlen (META_FILENAME));
+	mutex_unlock(&dtohd2(dentry)->d_inode->i_mutex);
 
 	/* We need to create a META-file */
         if(!meta_dentry->d_inode) {
@@ -527,9 +532,13 @@ int meta_write_r_entry(dentry_t *dentry,
 			goto out;
                 }
         }
+
+	mutex_lock(&dtohd2(dentry)->d_inode->i_mutex);
 	meta_dentry = lookup_one_len(META_FILENAME,
 				     dtohd2(dentry),
 				     strlen (META_FILENAME));
+	mutex_unlock(&dtohd2(dentry)->d_inode->i_mutex);
+
         if(!meta_dentry->d_inode) {
                 /* We need to create a META-file */
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
@@ -641,9 +650,13 @@ int meta_sync_d_list(dentry_t *dentry, i
 			goto out;
                 }
         }
+
+	mutex_lock(&dtohd2(dentry)->d_inode->i_mutex);
 	meta_dentry = lookup_one_len(META_FILENAME,
 				     dtohd2(dentry),
 				     strlen(META_FILENAME));
+	mutex_unlock(&dtohd2(dentry)->d_inode->i_mutex);
+
         if(!meta_dentry->d_inode) {
                 /* We need to create a META-file */
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
@@ -784,9 +797,13 @@ int meta_sync_r_list(dentry_t *dentry, i
 			goto out;
                 }
         }
+
+	mutex_lock(&dtohd2(dentry)->d_inode->i_mutex);
 	meta_dentry = lookup_one_len(META_FILENAME,
 				     dtohd2(dentry),
 				     strlen(META_FILENAME));
+	mutex_unlock(&dtohd2(dentry)->d_inode->i_mutex);
+
         if(!meta_dentry->d_inode) {
                 /* We need to create a META-file */
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)