/* * Functions related to mapping data to requests */#include <linux/kernel.h>#include <linux/module.h>#include <linux/bio.h>#include <linux/blkdev.h>#include <linux/uio.h> #include "blk.h" int blk_rq_append_bio(struct request_queue *q, struct request *rq,		      struct bio *bio){	if (!rq->bio)		blk_rq_bio_prep(q, rq, bio);	else if (!ll_back_merge_fn(q, rq, bio))		return -EINVAL;	else {		rq->biotail->bi_next = bio;		rq->biotail = bio; 		rq->__data_len += bio->bi_iter.bi_size;	}	return 0;} static int __blk_rq_unmap_user(struct bio *bio){	int ret = 0; 	if (bio) {		if (bio_flagged(bio, BIO_USER_MAPPED))			bio_unmap_user(bio);		else			ret = bio_uncopy_user(bio);	} 	return ret;} /** * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage * @q:		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) * @iter:	iovec iterator * @gfp_mask:	memory allocation flags * * Description: *    Data 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. * *    Note: The 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. */int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,			struct rq_map_data *map_data,			const struct iov_iter *iter, gfp_t gfp_mask){	struct bio *bio;	int unaligned = 0;	struct iov_iter i;	struct iovec iov; 	if (!iter || !iter->count)		return -EINVAL; 	iov_for_each(iov, i, *iter) {		unsigned long uaddr = (unsigned long) iov.iov_base; 		if (!iov.iov_len)			return -EINVAL; 		/*		 * Keep going so we check length of all segments		 */		if (uaddr & queue_dma_alignment(q))			unaligned = 1;	} 	if (unaligned || (q->dma_pad_mask & iter->count) || map_data)		bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);	else		bio = bio_map_user_iov(q, iter, gfp_mask); 	if (IS_ERR(bio))		return PTR_ERR(bio); 	if (map_data && map_data->null_mapped)		bio->bi_flags |= (1 << BIO_NULL_MAPPED); 	if (bio->bi_iter.bi_size != iter->count) {		/*		 * Grab an extra reference to this bio, as bio_unmap_user()		 * expects to be able to drop it twice as it happens on the		 * normal IO completion path		 */		bio_get(bio);		bio_endio(bio, 0);		__blk_rq_unmap_user(bio);		return -EINVAL;	} 	if (!bio_flagged(bio, BIO_USER_MAPPED))		rq->cmd_flags |= REQ_COPY_USER; 	blk_queue_bounce(q, &bio);	bio_get(bio);	blk_rq_bio_prep(q, rq, bio);	return 0;}EXPORT_SYMBOL(blk_rq_map_user_iov); int blk_rq_map_user(struct request_queue *q, struct request *rq,		    struct rq_map_data *map_data, void __user *ubuf,		    unsigned long len, gfp_t gfp_mask){	struct iovec iov;	struct iov_iter i;	int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i); 	if (unlikely(ret < 0))		return ret; 	return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);}EXPORT_SYMBOL(blk_rq_map_user); /** * blk_rq_unmap_user - unmap a request with user data * @bio:	       start of bio list * * Description: *    Unmap a rq previously mapped by blk_rq_map_user(). The caller must *    supply the original rq->bio from the blk_rq_map_user() return, since *    the I/O completion may have changed rq->bio. */int blk_rq_unmap_user(struct bio *bio){	struct bio *mapped_bio;	int ret = 0, ret2; 	while (bio) {		mapped_bio = bio;		if (unlikely(bio_flagged(bio, BIO_BOUNCED)))			mapped_bio = bio->bi_private; 		ret2 = __blk_rq_unmap_user(mapped_bio);		if (ret2 && !ret)			ret = ret2; 		mapped_bio = bio;		bio = bio->bi_next;		bio_put(mapped_bio);	} 	return ret;}EXPORT_SYMBOL(blk_rq_unmap_user); /** * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage * @q:		request queue where request should be inserted * @rq:		request to fill * @kbuf:	the kernel buffer * @len:	length of user data * @gfp_mask:	memory allocation flags * * Description: *    Data will be mapped directly if possible. Otherwise a bounce *    buffer is used. Can be called multiple times to append multiple *    buffers. */int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,		    unsigned int len, gfp_t gfp_mask){	int reading = rq_data_dir(rq) == READ;	unsigned long addr = (unsigned long) kbuf;	int do_copy = 0;	struct bio *bio;	int ret; 	if (len > (queue_max_hw_sectors(q) << 9))		return -EINVAL;	if (!len || !kbuf)		return -EINVAL; 	do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf);	if (do_copy)		bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);	else		bio = bio_map_kern(q, kbuf, len, gfp_mask); 	if (IS_ERR(bio))		return PTR_ERR(bio); 	if (!reading)		bio->bi_rw |= REQ_WRITE; 	if (do_copy)		rq->cmd_flags |= REQ_COPY_USER; 	ret = blk_rq_append_bio(q, rq, bio);	if (unlikely(ret)) {		/* request is too big */		bio_put(bio);		return ret;	} 	blk_queue_bounce(q, &rq->bio);	return 0;}EXPORT_SYMBOL(blk_rq_map_kern);