block: provide a blk_rq_map_sg variant that returns the last element

To be able to move some of the special purpose hacks in blk_rq_map_sg
into the callers we need a variant that returns the last mapped
S/G list element to the caller.  Add that variant as __blk_rq_map_sg
and make blk_rq_map_sg a trivial inline wrapper around it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
2020-04-14 09:42:22 +02:00
committed by Jens Axboe
parent e64a0e1692
commit 89de1504d5
2 changed files with 21 additions and 14 deletions

View File

@@ -1136,7 +1136,15 @@ static inline unsigned short blk_rq_nr_discard_segments(struct request *rq)
return max_t(unsigned short, rq->nr_phys_segments, 1);
}
extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
int __blk_rq_map_sg(struct request_queue *q, struct request *rq,
struct scatterlist *sglist, struct scatterlist **last_sg);
static inline int blk_rq_map_sg(struct request_queue *q, struct request *rq,
struct scatterlist *sglist)
{
struct scatterlist *last_sg = NULL;
return __blk_rq_map_sg(q, rq, sglist, &last_sg);
}
extern void blk_dump_rq_flags(struct request *, char *);
extern long nr_blockdev_pages(void);