Man page 9 : d_path

d_path - return the path of a dentry

char * d_path(const struct path *  path , char *  buf , int  buflen );

path
    path to report

buf
    buffer to return value in

buflen
    buffer length

Convert a dentry into an ASCII path name. If the entry has been deleted the string « (deleted) » is appended. Note that this is ambiguous.

Returns a pointer into the buffer or an error code if the path was too long. Note: Callers should use the returned pointer, not the passed in buffer, to use the name! The implementation often starts at an offset into the buffer, and may leave 0 bytes at the start.

« buflen » should be positive.