/* * Functions related to mapping data to requests */#include <linux/kernel.h>#include <linux/module.h>#include <linux/bio.h>#include <linux/blkdev.h>#include <scsi/sg.h>		/* for struct sg_iovec */ #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_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;} static int __blk_rq_map_user(struct request_queue *q, struct request *rq,			     struct rq_map_data *map_data, void __user *ubuf,			     unsigned int len, gfp_t gfp_mask){	unsigned long uaddr;	struct bio *bio, *orig_bio;	int reading, ret; 	reading = rq_data_dir(rq) == READ; 	/*	 * if alignment requirement is satisfied, map in user pages for	 * direct dma. else, set up kernel bounce buffers	 */	uaddr = (unsigned long) ubuf;	if (blk_rq_aligned(q, uaddr, len) && !map_data)		bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);	else		bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask); 	if (IS_ERR(bio))		return PTR_ERR(bio); 	if (map_data && map_data->null_mapped)		bio->bi_flags |= (1 << BIO_NULL_MAPPED); 	orig_bio = bio;	blk_queue_bounce(q, &bio); 	/*	 * We link the bounce buffer in and could have to traverse it	 * later so we have to get a ref to prevent it from being freed	 */	bio_get(bio); 	ret = blk_rq_append_bio(q, rq, bio);	if (!ret)		return bio->bi_size; 	/* if it was boucned we must call the end io function */	bio_endio(bio, 0);	__blk_rq_unmap_user(orig_bio);	bio_put(bio);	return ret;} /** * blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage * @q:		request queue where request should be inserted * @rq:		request structure to fill * @map_data:   pointer to the rq_map_data holding pages (if necessary) * @ubuf:	the user buffer * @len:	length of user data * @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(struct request_queue *q, struct request *rq,		    struct rq_map_data *map_data, void __user *ubuf,		    unsigned long len, gfp_t gfp_mask){	unsigned long bytes_read = 0;	struct bio *bio = NULL;	int ret; 	if (len > (queue_max_hw_sectors(q) << 9))		return -EINVAL;	if (!len)		return -EINVAL; 	if (!ubuf && (!map_data || !map_data->null_mapped))		return -EINVAL; 	while (bytes_read != len) {		unsigned long map_len, end, start; 		map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);		end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)								>> PAGE_SHIFT;		start = (unsigned long)ubuf >> PAGE_SHIFT; 		/*		 * A bad offset could cause us to require BIO_MAX_PAGES + 1		 * pages. If this happens we just lower the requested		 * mapping len by a page so that we can fit		 */		if (end - start > BIO_MAX_PAGES)			map_len -= PAGE_SIZE; 		ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,					gfp_mask);		if (ret < 0)			goto unmap_rq;		if (!bio)			bio = rq->bio;		bytes_read += ret;		ubuf += ret; 		if (map_data)			map_data->offset += ret;	} 	if (!bio_flagged(bio, BIO_USER_MAPPED))		rq->cmd_flags |= REQ_COPY_USER; 	rq->buffer = NULL;	return 0;unmap_rq:	blk_rq_unmap_user(bio);	rq->bio = NULL;	return ret;}EXPORT_SYMBOL(blk_rq_map_user); /** * 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) * @iov:	pointer to the iovec * @iov_count:	number of elements in the iovec * @len:	I/O byte count * @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, struct sg_iovec *iov,			int iov_count, unsigned int len, gfp_t gfp_mask){	struct bio *bio;	int i, read = rq_data_dir(rq) == READ;	int unaligned = 0; 	if (!iov || iov_count <= 0)		return -EINVAL; 	for (i = 0; i < iov_count; i++) {		unsigned long uaddr = (unsigned long)iov[i].iov_base; 		if (!iov[i].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 & len) || map_data)		bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,					gfp_mask);	else		bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask); 	if (IS_ERR(bio))		return PTR_ERR(bio); 	if (bio->bi_size != len) {		/*		 * 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);	rq->buffer = NULL;	return 0;}EXPORT_SYMBOL(blk_rq_map_user_iov); /** * 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 multple times to append multple *    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);	rq->buffer = NULL;	return 0;}EXPORT_SYMBOL(blk_rq_map_kern);