261 lines
6.0 KiB
C
261 lines
6.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Functions related to mapping data to requests
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*/
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#include <linux/kernel.h>
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#include <linux/sched/task_stack.h>
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#include <linux/module.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/uio.h>
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#include "blk.h"
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/*
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* Append a bio to a passthrough request. Only works if the bio can be merged
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* into the request based on the driver constraints.
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*/
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int blk_rq_append_bio(struct request *rq, struct bio **bio)
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{
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struct bio *orig_bio = *bio;
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struct bvec_iter iter;
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struct bio_vec bv;
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unsigned int nr_segs = 0;
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blk_queue_bounce(rq->q, bio);
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bio_for_each_bvec(bv, *bio, iter)
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nr_segs++;
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if (!rq->bio) {
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blk_rq_bio_prep(rq, *bio, nr_segs);
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} else {
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if (!ll_back_merge_fn(rq, *bio, nr_segs)) {
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if (orig_bio != *bio) {
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bio_put(*bio);
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*bio = orig_bio;
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}
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return -EINVAL;
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}
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rq->biotail->bi_next = *bio;
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rq->biotail = *bio;
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rq->__data_len += (*bio)->bi_iter.bi_size;
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}
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return 0;
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}
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EXPORT_SYMBOL(blk_rq_append_bio);
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static int __blk_rq_unmap_user(struct bio *bio)
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{
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int ret = 0;
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if (bio) {
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if (bio_flagged(bio, BIO_USER_MAPPED))
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bio_unmap_user(bio);
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else
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ret = bio_uncopy_user(bio);
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}
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return ret;
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}
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static int __blk_rq_map_user_iov(struct request *rq,
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struct rq_map_data *map_data, struct iov_iter *iter,
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gfp_t gfp_mask, bool copy)
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{
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struct request_queue *q = rq->q;
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struct bio *bio, *orig_bio;
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int ret;
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if (copy)
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bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);
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else
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bio = bio_map_user_iov(q, iter, gfp_mask);
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if (IS_ERR(bio))
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return PTR_ERR(bio);
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bio->bi_opf &= ~REQ_OP_MASK;
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bio->bi_opf |= req_op(rq);
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orig_bio = bio;
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/*
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* We link the bounce buffer in and could have to traverse it
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* later so we have to get a ref to prevent it from being freed
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*/
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ret = blk_rq_append_bio(rq, &bio);
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if (ret) {
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__blk_rq_unmap_user(orig_bio);
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return ret;
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}
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bio_get(bio);
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return 0;
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}
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/**
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* blk_rq_map_user_iov - map user data to a request, for passthrough requests
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* @q: request queue where request should be inserted
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* @rq: request to map data to
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* @map_data: pointer to the rq_map_data holding pages (if necessary)
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* @iter: iovec iterator
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* @gfp_mask: memory allocation flags
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*
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* Description:
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* Data will be mapped directly for zero copy I/O, if possible. Otherwise
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* a kernel bounce buffer is used.
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*
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* A matching blk_rq_unmap_user() must be issued at the end of I/O, while
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* still in process context.
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*
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* Note: The mapped bio may need to be bounced through blk_queue_bounce()
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* before being submitted to the device, as pages mapped may be out of
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* reach. It's the callers responsibility to make sure this happens. The
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* original bio must be passed back in to blk_rq_unmap_user() for proper
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* unmapping.
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*/
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int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
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struct rq_map_data *map_data,
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const struct iov_iter *iter, gfp_t gfp_mask)
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{
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bool copy = false;
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unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
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struct bio *bio = NULL;
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struct iov_iter i;
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int ret = -EINVAL;
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if (!iter_is_iovec(iter))
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goto fail;
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if (map_data)
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copy = true;
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else if (iov_iter_alignment(iter) & align)
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copy = true;
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else if (queue_virt_boundary(q))
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copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
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i = *iter;
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do {
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ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
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if (ret)
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goto unmap_rq;
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if (!bio)
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bio = rq->bio;
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} while (iov_iter_count(&i));
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if (!bio_flagged(bio, BIO_USER_MAPPED))
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rq->rq_flags |= RQF_COPY_USER;
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return 0;
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unmap_rq:
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blk_rq_unmap_user(bio);
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fail:
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rq->bio = NULL;
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return ret;
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}
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EXPORT_SYMBOL(blk_rq_map_user_iov);
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int blk_rq_map_user(struct request_queue *q, struct request *rq,
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struct rq_map_data *map_data, void __user *ubuf,
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unsigned long len, gfp_t gfp_mask)
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{
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struct iovec iov;
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struct iov_iter i;
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int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i);
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if (unlikely(ret < 0))
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return ret;
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return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);
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}
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EXPORT_SYMBOL(blk_rq_map_user);
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/**
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* blk_rq_unmap_user - unmap a request with user data
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* @bio: start of bio list
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*
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* Description:
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* Unmap a rq previously mapped by blk_rq_map_user(). The caller must
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* supply the original rq->bio from the blk_rq_map_user() return, since
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* the I/O completion may have changed rq->bio.
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*/
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int blk_rq_unmap_user(struct bio *bio)
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{
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struct bio *mapped_bio;
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int ret = 0, ret2;
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while (bio) {
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mapped_bio = bio;
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if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
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mapped_bio = bio->bi_private;
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ret2 = __blk_rq_unmap_user(mapped_bio);
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if (ret2 && !ret)
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ret = ret2;
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mapped_bio = bio;
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bio = bio->bi_next;
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bio_put(mapped_bio);
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}
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return ret;
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}
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EXPORT_SYMBOL(blk_rq_unmap_user);
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/**
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* blk_rq_map_kern - map kernel data to a request, for passthrough requests
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* @q: request queue where request should be inserted
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* @rq: request to fill
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* @kbuf: the kernel buffer
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* @len: length of user data
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* @gfp_mask: memory allocation flags
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*
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* Description:
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* Data will be mapped directly if possible. Otherwise a bounce
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* buffer is used. Can be called multiple times to append multiple
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* buffers.
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*/
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int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
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unsigned int len, gfp_t gfp_mask)
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{
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int reading = rq_data_dir(rq) == READ;
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unsigned long addr = (unsigned long) kbuf;
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int do_copy = 0;
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struct bio *bio, *orig_bio;
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int ret;
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if (len > (queue_max_hw_sectors(q) << 9))
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return -EINVAL;
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if (!len || !kbuf)
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return -EINVAL;
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do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf);
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if (do_copy)
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bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
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else
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bio = bio_map_kern(q, kbuf, len, gfp_mask);
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if (IS_ERR(bio))
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return PTR_ERR(bio);
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bio->bi_opf &= ~REQ_OP_MASK;
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bio->bi_opf |= req_op(rq);
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if (do_copy)
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rq->rq_flags |= RQF_COPY_USER;
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orig_bio = bio;
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ret = blk_rq_append_bio(rq, &bio);
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if (unlikely(ret)) {
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/* request is too big */
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bio_put(orig_bio);
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return ret;
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}
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return 0;
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}
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EXPORT_SYMBOL(blk_rq_map_kern);
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