Man page 9 : generic_pipe_buf_steal

generic_pipe_buf_steal - attempt to take ownership of a pipe_buffer

int generic_pipe_buf_steal(struct pipe_inode_info *  pipe , struct pipe_buffer *  buf );

pipe
    the pipe that the buffer belongs to

buf
    the buffer to attempt to steal

This function attempts to steal the struct page attached to buf. If successful, this function returns 0 and returns with the page locked. The caller may then reuse the page for whatever he wishes; the typical use is insertion into a different file page cache.