/* * 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_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; } 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_iter.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_iter.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);