linux/block/blk-map.c
Christoph Hellwig 14ccb66b3f block: remove the bi_phys_segments field in struct bio
We only need the number of segments in the blk-mq submission path.
Remove the field from struct bio, and return it from a variant of
blk_queue_split instead of that it can passed as an argument to
those functions that need the value.

This also means we stop recounting segments except for cloning
and partial segments.

To keep the number of arguments in this how path down remove
pointless struct request_queue arguments from any of the functions
that had it and grew a nr_segs argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-20 10:29:22 -06:00

261 lines
6.0 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Functions related to mapping data to requests
*/
#include <linux/kernel.h>
#include <linux/sched/task_stack.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/uio.h>
#include "blk.h"
/*
* Append a bio to a passthrough request. Only works if the bio can be merged
* into the request based on the driver constraints.
*/
int blk_rq_append_bio(struct request *rq, struct bio **bio)
{
struct bio *orig_bio = *bio;
struct bvec_iter iter;
struct bio_vec bv;
unsigned int nr_segs = 0;
blk_queue_bounce(rq->q, bio);
bio_for_each_bvec(bv, *bio, iter)
nr_segs++;
if (!rq->bio) {
blk_rq_bio_prep(rq, *bio, nr_segs);
} else {
if (!ll_back_merge_fn(rq, *bio, nr_segs)) {
if (orig_bio != *bio) {
bio_put(*bio);
*bio = orig_bio;
}
return -EINVAL;
}
rq->biotail->bi_next = *bio;
rq->biotail = *bio;
rq->__data_len += (*bio)->bi_iter.bi_size;
}
return 0;
}
EXPORT_SYMBOL(blk_rq_append_bio);
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_iov(struct request *rq,
struct rq_map_data *map_data, struct iov_iter *iter,
gfp_t gfp_mask, bool copy)
{
struct request_queue *q = rq->q;
struct bio *bio, *orig_bio;
int ret;
if (copy)
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);
bio->bi_opf &= ~REQ_OP_MASK;
bio->bi_opf |= req_op(rq);
orig_bio = 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
*/
ret = blk_rq_append_bio(rq, &bio);
if (ret) {
__blk_rq_unmap_user(orig_bio);
return ret;
}
bio_get(bio);
return 0;
}
/**
* blk_rq_map_user_iov - map user data to a request, for passthrough requests
* @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)
{
bool copy = false;
unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
struct bio *bio = NULL;
struct iov_iter i;
int ret = -EINVAL;
if (!iter_is_iovec(iter))
goto fail;
if (map_data)
copy = true;
else if (iov_iter_alignment(iter) & align)
copy = true;
else if (queue_virt_boundary(q))
copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
i = *iter;
do {
ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
if (ret)
goto unmap_rq;
if (!bio)
bio = rq->bio;
} while (iov_iter_count(&i));
if (!bio_flagged(bio, BIO_USER_MAPPED))
rq->rq_flags |= RQF_COPY_USER;
return 0;
unmap_rq:
__blk_rq_unmap_user(bio);
fail:
rq->bio = NULL;
return ret;
}
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 passthrough requests
* @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, *orig_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);
bio->bi_opf &= ~REQ_OP_MASK;
bio->bi_opf |= req_op(rq);
if (do_copy)
rq->rq_flags |= RQF_COPY_USER;
orig_bio = bio;
ret = blk_rq_append_bio(rq, &bio);
if (unlikely(ret)) {
/* request is too big */
bio_put(orig_bio);
return ret;
}
return 0;
}
EXPORT_SYMBOL(blk_rq_map_kern);