generic_make_request — hand a buffer to its device driver for I/O
blk_qc_t generic_make_request ( | struct bio * bio); |
generic_make_request is used to make I/O requests of block
devices. It is passed a struct bio, which describes the I/O that needs
to be done.
generic_make_request does not return any status. The
success/failure status of the request, along with notification of
completion, is delivered asynchronously through the bio->bi_end_io
function described (one day) else where.
The caller of generic_make_request must make sure that bi_io_vec are set to describe the memory buffer, and that bi_dev and bi_sector are set to describe the device address, and the bi_end_io and optionally bi_private are set to describe how completion notification should be signaled.
generic_make_request and the drivers it calls may use bi_next if this bio happens to be merged with someone else, and may resubmit the bio to a lower device by calling into generic_make_request recursively, which means the bio should NOT be touched after the call to ->make_request_fn.