// 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"
struct bio_map_data {
bool is_our_pages : 1;
bool is_null_mapped : 1;
struct iov_iter iter;
struct iovec iov[];
};
static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data,
gfp_t gfp_mask)
{
struct bio_map_data *bmd;
if (data->nr_segs > UIO_MAXIOV)
return NULL;
bmd = kmalloc(struct_size(bmd, iov, data->nr_segs), gfp_mask);
if (!bmd)
return NULL;
bmd->iter = *data;
if (iter_is_iovec(data)) {
memcpy(bmd->iov, iter_iov(data), sizeof(struct iovec) * data->nr_segs);
bmd->iter.__iov = bmd->iov;
}
return bmd;
}
/**
* bio_copy_from_iter - copy all pages from iov_iter to bio
* @bio: The &struct bio which describes the I/O as destination
* @iter: iov_iter as source
*
* Copy all pages from iov_iter to bio.
* Returns 0 on success, or error on failure.
*/
static int bio_copy_from_iter(struct bio *bio, struct iov_iter *iter)
{
struct bio_vec *bvec;
struct bvec_iter_all iter_all;
bio_for_each_segment_all(bvec, bio, iter_all) {
ssize_t ret;
ret = copy_page_from_iter(bvec->bv_page,
bvec->bv_offset,
bvec->bv_len,
iter);
if (!iov_iter_count(iter))
break;
if (ret < bvec->bv_len)
return -EFAULT;
}
return 0;
}
/**
* bio_copy_to_iter - copy all pages from bio to iov_iter
* @bio: The &struct bio which describes the I/O as source
* @iter: iov_iter as destination
*
* Copy all pages from bio to iov_iter.
* Returns 0 on success, or error on failure.
*/
static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter)
{
struct bio_vec *bvec;
struct bvec_iter_all iter_all;
bio_for_each_segment_all(bvec, bio, iter_all) {
ssize_t ret;
ret = copy_page_to_iter(bvec->bv_page,
bvec->bv_offset,
bvec->bv_len,
&iter);
if (!iov_iter_count(&iter))
break;
if (ret < bvec->bv_len)
return -EFAULT;
}
return 0;
}
/**
* bio_uncopy_user - finish previously mapped bio
* @bio: bio being terminated
*
* Free pages allocated from bio_copy_user_iov() and write back data
* to user space in case of a read.
*/
static int bio_uncopy_user(struct bio *bio)
{
struct bio_map_data *bmd = bio->bi_private;
int ret = 0;
if (!bmd->is_null_mapped) {
/*
* if we're in a workqueue, the request is orphaned, so
* don't copy into a random user address space, just free
* and return -EINTR so user space doesn't expect any data.
*/
if (!current->mm)
ret = -EINTR;
else if (bio_data_dir(bio) == READ)
ret = bio_copy_to_iter(bio, bmd->iter);
if (bmd->is_our_pages)
bio_free_pages(bio);
}
kfree(bmd);
return ret;
}
static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
struct iov_iter *iter, gfp_t gfp_mask)
{
struct bio_map_data *bmd;
struct page *page;
struct bio *bio;
int i = 0, ret;
int nr_pages;
unsigned int len = iter->count;
unsigned int offset = map_data ? offset_in_page(map_data->offset) : 0;
bmd = bio_alloc_map_data(iter, gfp_mask);
if (!bmd)
return -ENOMEM;
/*
* We need to do a deep copy of the iov_iter including the iovecs.
* The caller provided iov might point to an on-stack or otherwise
* shortlived one.
*/
bmd->is_our_pages = !map_data;
bmd->is_null_mapped = (map_data && map_data->null_mapped);
nr_pages = bio_max_segs(DIV_ROUND_UP(offset + len, PAGE_SIZE));
ret = -ENOMEM;
bio = bio_kmalloc(nr_pages, gfp_mask);
if (!bio)
goto out_bmd;
bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, req_op(rq));
if (map_data) {
nr_pages = 1U << map_data->page_order;
i = map_data->offset / PAGE_SIZE;
}
while (len) {
unsigned int bytes = PAGE_SIZE;
bytes -= offset;
if (bytes > len)
bytes = len;
if (map_data) {
if (i == map_data->nr_entries * nr_pages) {
ret = -ENOMEM;
goto cleanup;
}
page = map_data->pages[i / nr_pages];
page += (i % nr_pages);
i++;
} else {
page = alloc_page(GFP_NOIO | gfp_mask);
if (!page) {
ret = -ENOMEM;
goto cleanup;
}
}
if (bio_add_pc_page(rq->q, bio, page, bytes, offset) < bytes) {
if (!map_data)
__free_page(page);
break;
}
len -= bytes;
offset = 0;
}
if (map_data)
map_data->offset += bio->bi_iter.bi_size;
/*
* success
*/
if (iov_iter_rw(iter) == WRITE &&
(!map_data || !map_data->null_mapped)) {
ret = bio_copy_from_iter(bio, iter);
if (ret)
goto cleanup;
} else if (map_data && map_data->from_user) {
struct iov_iter iter2 = *iter;
/* This is the copy-in part of SG_DXFER_TO_FROM_DEV. */
iter2.data_source = ITER_SOURCE;
ret = bio_copy_from_iter(bio, &iter2);
if (ret)
goto cleanup;
} else {
if (bmd->is_our_pages)
zero_fill_bio(bio);
iov_iter_advance(iter, bio->bi_iter.bi_size);
}
bio->bi_private = bmd;
ret = blk_rq_append_bio(rq, bio);
if (ret)
goto cleanup;
return 0;
cleanup:
if (!map_data)
bio_free_pages(bio);
bio_uninit(bio);
kfree(bio);
out_bmd:
kfree(bmd);
return ret;
}
static void blk_mq_map_bio_put(struct bio *bio)
{
if (bio->bi_opf & REQ_ALLOC_CACHE) {
bio_put(bio);
} else {
bio_uninit(bio);
kfree(bio);
}
}
static struct bio *blk_rq_map_bio_alloc(struct request *rq,
unsigned int nr_vecs, gfp_t gfp_mask)
{
struct bio *bio;
if (rq->cmd_flags & REQ_ALLOC_CACHE && (nr_vecs <= BIO_INLINE_VECS)) {
bio = bio_alloc_bioset(NULL, nr_vecs, rq->cmd_flags, gfp_mask,
&fs_bio_set);
if (!bio)
return NULL;
} else {
bio = bio_kmalloc(nr_vecs, gfp_mask);
if (!bio)
return NULL;
bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs, req_op(rq));
}
return bio;
}
static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
gfp_t gfp_mask)
{
iov_iter_extraction_t extraction_flags = 0;
unsigned int max_sectors = queue_max_hw_sectors(rq->q);
unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
struct bio *bio;
int ret;
int j;
if (!iov_iter_count(iter))
return -EINVAL;
bio = blk_rq_map_bio_alloc(rq, nr_vecs, gfp_mask);
if (bio == NULL)
return -ENOMEM;
if (blk_queue_pci_p2pdma(rq->q))
extraction_flags |= ITER_ALLOW_P2PDMA;
if (iov_iter_extract_will_pin(iter))
bio_set_flag(bio, BIO_PAGE_PINNED);
while (iov_iter_count(iter)) {
struct page *stack_pages[UIO_FASTIOV];
struct page **pages = stack_pages;
ssize_t bytes;
size_t offs;
int npages;
if (nr_vecs > ARRAY_SIZE(stack_pages))
pages = NULL;
bytes = iov_iter_extract_pages(iter, &pages, LONG_MAX,
nr_vecs, extraction_flags, &offs);
if (unlikely(bytes <= 0)) {
ret = bytes ? bytes : -EFAULT;
goto out_unmap;
}
npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE);
if (unlikely(offs & queue_dma_alignment(rq->q)))
j = 0;
else {
for (j = 0; j < npages; j++) {
struct page *page = pages[j];
unsigned int n = PAGE_SIZE - offs;
bool same_page = false;
if (n > bytes)
n = bytes;
if (!bio_add_hw_page(rq->q, bio, page, n, offs,
max_sectors, &same_page))
break;
if (same_page)
bio_release_page(bio, page);
bytes -= n;
offs = 0;
}
}
/*
* release the pages we didn't map into the bio, if any
*/
while (j < npages)
bio_release_page(bio, pages[j++]);
if (pages != stack_pages)
kvfree(pages);
/* couldn't stuff something into bio? */
if (bytes) {
iov_iter_revert(iter, bytes);
break;
}
}
ret = blk_rq_append_bio(rq, bio);
if (ret)
goto out_unmap;
return 0;
out_unmap:
bio_release_pages(bio, false);
blk_mq_map_bio_put(bio);
return ret;
}
static void bio_invalidate_vmalloc_pages(struct bio *bio)
{
#ifdef ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE
if (bio->bi_private && !op_is_write(bio_op(bio))) {
unsigned long i, len = 0;
for (i = 0; i < bio->bi_vcnt; i++)
len += bio->bi_io_vec[i].bv_len;
invalidate_kernel_vmap_range(bio->bi_private, len);
}
#endif
}
static void bio_map_kern_endio(struct bio *bio)
{
bio_invalidate_vmalloc_pages(bio);
bio_uninit(bio);
kfree(bio);
}
/**
* bio_map_kern - map kernel address into bio
* @q: the struct request_queue for the bio
* @data: pointer to buffer to map
* @len: length in bytes
* @gfp_mask: allocation flags for bio allocation
*
* Map the kernel address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
static struct bio *bio_map_kern(struct request_queue *q, void *data,
unsigned int len, gfp_t gfp_mask)
{
unsigned long kaddr = (unsigned long)data;
unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = kaddr >> PAGE_SHIFT;
const int nr_pages = end - start;
bool is_vmalloc = is_vmalloc_addr(data);
struct page *page;
int offset, i;
struct bio *bio;
bio = bio_kmalloc(nr_pages, gfp_mask);
if (!bio)
return ERR_PTR(-ENOMEM);
bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0);
if (is_vmalloc) {
flush_kernel_vmap_range(data, len);
bio->bi_private = data;
}
offset = offset_in_page(kaddr);
for (i = 0; i < nr_pages; i++) {
unsigned int bytes = PAGE_SIZE - offset;
if (len <= 0)
break;
if (bytes > len)
bytes = len;
if (!is_vmalloc)
page = virt_to_page(data);
else
page = vmalloc_to_page(data);
if (bio_add_pc_page(q, bio, page, bytes,
offset) < bytes) {
/* we don't support partial mappings */
bio_uninit(bio);
kfree(bio);
return ERR_PTR(-EINVAL);
}
data += bytes;
len -= bytes;
offset = 0;
}
bio->bi_end_io = bio_map_kern_endio;
return bio;
}
static void bio_copy_kern_endio(struct bio *bio)
{
bio_free_pages(bio);
bio_uninit(bio);
kfree(bio);
}
static void bio_copy_kern_endio_read(struct bio *bio)
{
char *p = bio->bi_private;
struct bio_vec *bvec;
struct bvec_iter_all iter_all;
bio_for_each_segment_all(bvec, bio, iter_all) {
memcpy_from_bvec(p, bvec);
p += bvec->bv_len;
}
bio_copy_kern_endio(bio);
}
/**
* bio_copy_kern - copy kernel address into bio
* @q: the struct request_queue for the bio
* @data: pointer to buffer to copy
* @len: length in bytes
* @gfp_mask: allocation flags for bio and page allocation
* @reading: data direction is READ
*
* copy the kernel address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
static struct bio *bio_copy_kern(struct request_queue *q, void *data,
unsigned int len, gfp_t gfp_mask, int reading)
{
unsigned long kaddr = (unsigned long)data;
unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = kaddr >> PAGE_SHIFT;
struct bio *bio;
void *p = data;
int nr_pages = 0;
/*
* Overflow, abort
*/
if (end < start)
return ERR_PTR(-EINVAL);
nr_pages = end - start;
bio = bio_kmalloc(nr_pages, gfp_mask);
if (!bio)
return ERR_PTR(-ENOMEM);
bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0);
while (len) {
struct page *page;
unsigned int bytes = PAGE_SIZE;
if (bytes > len)
bytes = len;
page = alloc_page(GFP_NOIO | __GFP_ZERO | gfp_mask);
if (!page)
goto cleanup;
if (!reading)
memcpy(page_address(page), p, bytes);
if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
break;
len -= bytes;
p += bytes;
}
if (reading) {
bio->bi_end_io = bio_copy_kern_endio_read;
bio->bi_private = data;
} else {
bio->bi_end_io = bio_copy_kern_endio;
}
return bio;
cleanup:
bio_free_pages(bio);
bio_uninit(bio);
kfree(bio);
return ERR_PTR(-ENOMEM);
}
/*
* 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 bvec_iter iter;
struct bio_vec bv;
unsigned int nr_segs = 0;
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))
return -EINVAL;
rq->biotail->bi_next = bio;
rq->biotail = bio;
rq->__data_len += (bio)->bi_iter.bi_size;
bio_crypt_free_ctx(bio);
}
return 0;
}
EXPORT_SYMBOL(blk_rq_append_bio);
/* Prepare bio for passthrough IO given ITER_BVEC iter */
static int blk_rq_map_user_bvec(struct request *rq, const struct iov_iter *iter)
{
struct request_queue *q = rq->q;
size_t nr_iter = iov_iter_count(iter);
size_t nr_segs = iter->nr_segs;
struct bio_vec *bvecs, *bvprvp = NULL;
const struct queue_limits *lim = &q->limits;
unsigned int nsegs = 0, bytes = 0;
struct bio *bio;
size_t i;
if (!nr_iter || (nr_iter >> SECTOR_SHIFT) > queue_max_hw_sectors(q))
return -EINVAL;
if (nr_segs > queue_max_segments(q))
return -EINVAL;
/* no iovecs to alloc, as we already have a BVEC iterator */
bio = blk_rq_map_bio_alloc(rq, 0, GFP_KERNEL);
if (bio == NULL)
return -ENOMEM;
bio_iov_bvec_set(bio, (struct iov_iter *)iter);
blk_rq_bio_prep(rq, bio, nr_segs);
/* loop to perform a bunch of sanity checks */
bvecs = (struct bio_vec *)iter->bvec;
for (i = 0; i < nr_segs; i++) {
struct bio_vec *bv = &bvecs[i];
/*
* If the queue doesn't support SG gaps and adding this
* offset would create a gap, fallback to copy.
*/
if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv->bv_offset)) {
blk_mq_map_bio_put(bio);
return -EREMOTEIO;
}
/* check full condition */
if (nsegs >= nr_segs || bytes > UINT_MAX - bv->bv_len)
goto put_bio;
if (bytes + bv->bv_len > nr_iter)
goto put_bio;
if (bv->bv_offset + bv->bv_len > PAGE_SIZE)
goto put_bio;
nsegs++;
bytes += bv->bv_len;
bvprvp = bv;
}
return 0;
put_bio:
blk_mq_map_bio_put(bio);
return -EINVAL;
}
/**
* 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.
*/
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, map_bvec = false;
unsigned long align = blk_lim_dma_alignment_and_pad(&q->limits);
struct bio *bio = NULL;
struct iov_iter i;
int ret = -EINVAL;
if (map_data)
copy = true;
else if (blk_queue_may_bounce(q))
copy = true;
else if (iov_iter_alignment(iter) & align)
copy = true;
else if (iov_iter_is_bvec(iter))
map_bvec = true;
else if (!user_backed_iter(iter))
copy = true;
else if (queue_virt_boundary(q))
copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
if (map_bvec) {
ret = blk_rq_map_user_bvec(rq, iter);
if (!ret)
return 0;
if (ret != -EREMOTEIO)
goto fail;
/* fall back to copying the data on limits mismatches */
copy = true;
}
i = *iter;
do {
if (copy)
ret = bio_copy_user_iov(rq, map_data, &i, gfp_mask);
else
ret = bio_map_user_iov(rq, &i, gfp_mask);
if (ret)
goto unmap_rq;
if (!bio)
bio = rq->bio;
} while (iov_iter_count(&i));
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 iov_iter i;
int ret = import_ubuf(rq_data_dir(rq), ubuf, len, &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);
int blk_rq_map_user_io(struct request *req, struct rq_map_data *map_data,
void __user *ubuf, unsigned long buf_len, gfp_t gfp_mask,
bool vec, int iov_count, bool check_iter_count, int rw)
{
int ret = 0;
if (vec) {
struct iovec fast_iov[UIO_FASTIOV];
struct iovec *iov = fast_iov;
struct iov_iter iter;
ret = import_iovec(rw, ubuf, iov_count ? iov_count : buf_len,
UIO_FASTIOV, &iov, &iter);
if (ret < 0)
return ret;
if (iov_count) {
/* SG_IO howto says that the shorter of the two wins */
iov_iter_truncate(&iter, buf_len);
if (check_iter_count && !iov_iter_count(&iter)) {
kfree(iov);
return -EINVAL;
}
}
ret = blk_rq_map_user_iov(req->q, req, map_data, &iter,
gfp_mask);
kfree(iov);
} else if (buf_len) {
ret = blk_rq_map_user(req->q, req, map_data, ubuf, buf_len,
gfp_mask);
}
return ret;
}
EXPORT_SYMBOL(blk_rq_map_user_io);
/**
* 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 *next_bio;
int ret = 0, ret2;
while (bio) {
if (bio->bi_private) {
ret2 = bio_uncopy_user(bio);
if (ret2 && !ret)
ret = ret2;
} else {
bio_release_pages(bio, bio_data_dir(bio) == READ);
}
if (bio_integrity(bio))
bio_integrity_unmap_user(bio);
next_bio = bio;
bio = bio->bi_next;
blk_mq_map_bio_put(next_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;
struct bio *bio;
int ret;
if (len > (queue_max_hw_sectors(q) << 9))
return -EINVAL;
if (!len || !kbuf)
return -EINVAL;
if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf) ||
blk_queue_may_bounce(q))
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);
ret = blk_rq_append_bio(rq, bio);
if (unlikely(ret)) {
bio_uninit(bio);
kfree(bio);
}
return ret;
}
EXPORT_SYMBOL(blk_rq_map_kern);
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