Man page 9 : blk_update_request

blk_update_request - Special helper function for request stacking drivers

bool blk_update_request(struct request *  req , int  error , unsigned int  nr_bytes );

req
    the request being processed

error
     0 for success, < 0 for error

nr_bytes
    number of bytes to complete req

Ends I/O on a number of bytes attached to req, but doesnAqt complete the request structure even if req doesnAqt have leftover. If req has leftover, sets it up for the next range of segments.

This special helper function is only for request stacking drivers (e.g. request-based dm) so that they can handle partial completion. Actual device drivers should use blk_end_request instead.

Passing the result of blk_rq_bytes as nr_bytes guarantees false return from this function.

false - this request doesnAqt have any more data true - this request has more data