Query: blk_rq_map_user_iov
OS: centos
Section: 9
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BLK_RQ_MAP_USER_IOV(9) Block Devices BLK_RQ_MAP_USER_IOV(9)NAMEblk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usageSYNOPSISint blk_rq_map_user_iov(struct request_queue * q, struct request * rq, struct rq_map_data * map_data, struct sg_iovec * iov, int iov_count, unsigned int len, gfp_t gfp_mask);ARGUMENTSq request queue where request should be inserted rq request to map data to map_data pointer to the rq_map_data holding pages (if necessary) iov pointer to the iovec iov_count number of elements in the iovec len I/O byte count gfp_mask memory allocation flagsDESCRIPTIONData will be mapped directly for zero copy I/O, if possible. Otherwise a kernel bounce buffer is used. A matching blk_rq_unmap_user must be issued at the end of I/O, while still in process context.NOTEThe mapped bio may need to be bounced through blk_queue_bounce before being submitted to the device, as pages mapped may be out of reach. It's the callers responsibility to make sure this happens. The original bio must be passed back in to blk_rq_unmap_user for proper unmapping.COPYRIGHTKernel Hackers Manual 3.10 June 2014 BLK_RQ_MAP_USER_IOV(9)