suse man page for blk_rq_prep_clone

BLK_RQ_PREP_CLONE(9)						   Block Devices					      BLK_RQ_PREP_CLONE(9)

NAME
       blk_rq_prep_clone - Helper function to setup clone request

SYNOPSIS
       int blk_rq_prep_clone(struct request * rq, struct request * rq_src, struct bio_set * bs, gfp_t gfp_mask,
			     int (*bio_ctr) (struct bio *, struct bio *, void *), void * data);

ARGUMENTS
       rq
	   the request to be setup

       rq_src
	   original request to be cloned

       bs
	   bio_set that bios for clone are allocated from

       gfp_mask
	   memory allocation mask for bio

       bio_ctr
	   setup function to be called for each clone bio. Returns 0 for success, non 0 for failure.

       data
	   private data to be passed to bio_ctr

DESCRIPTION
       Clones bios in rq_src to rq, and copies attributes of rq_src to rq. The actual data parts of rq_src (e.g. ->cmd, ->buffer, ->sense) are not
       copied, and copying such parts is the caller's responsibility. Also, pages which the original bios are pointing to are not copied and the
       cloned bios just point same pages. So cloned bios must be completed before original bios, which means the caller must complete rq before
       rq_src.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010						      BLK_RQ_PREP_CLONE(9)