*
* If dir_dentry is passed, the caller has already locked the parent
* appropriately for this operation (normally a write lock). If
* dir_dentry is NULL, we do a read lock while we do the lookup to
* avoid races with create/destroy and such changing the directory
* internal to the filesystem code. */
*
* If dir_dentry is passed, the caller has already locked the parent
* appropriately for this operation (normally a write lock). If
* dir_dentry is NULL, we do a read lock while we do the lookup to
* avoid races with create/destroy and such changing the directory
* internal to the filesystem code. */