From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- block/blk-map.c | 220 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 220 insertions(+) create mode 100644 block/blk-map.c (limited to 'block/blk-map.c') diff --git a/block/blk-map.c b/block/blk-map.c new file mode 100644 index 000000000..da310a105 --- /dev/null +++ b/block/blk-map.c @@ -0,0 +1,220 @@ +/* + * Functions related to mapping data to requests + */ +#include +#include +#include +#include +#include + +#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); -- cgit v1.2.3-54-g00ecf