// 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 {
        int is_our_pages;
        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;
        memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs);
        bmd->iter = *data;
        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 (!bio_flagged(bio, BIO_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);
        bio_put(bio);
        return ret;
}

/**
 *      bio_copy_user_iov       -       copy user data to bio
 *      @q:             destination block queue
 *      @map_data:      pointer to the rq_map_data holding pages (if necessary)
 *      @iter:          iovec iterator
 *      @gfp_mask:      memory allocation flags
 *
 *      Prepares and returns a bio for indirect user io, bouncing data
 *      to/from kernel pages as necessary. Must be paired with
 *      call bio_uncopy_user() on io completion.
 */
static struct bio *bio_copy_user_iov(struct request_queue *q,
                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 ERR_PTR(-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 ? 0 : 1;

        nr_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE);
        if (nr_pages > BIO_MAX_PAGES)
                nr_pages = BIO_MAX_PAGES;

        ret = -ENOMEM;
        bio = bio_kmalloc(gfp_mask, nr_pages);
        if (!bio)
                goto out_bmd;

        ret = 0;

        if (map_data) {
                nr_pages = 1 << 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;
                                break;
                        }

                        page = map_data->pages[i / nr_pages];
                        page += (i % nr_pages);

                        i++;
                } else {
                        page = alloc_page(q->bounce_gfp | gfp_mask);
                        if (!page) {
                                ret = -ENOMEM;
                                break;
                        }
                }

                if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes) {
                        if (!map_data)
                                __free_page(page);
                        break;
                }

                len -= bytes;
                offset = 0;
        }

        if (ret)
                goto cleanup;

        if (map_data)
                map_data->offset += bio->bi_iter.bi_size;

        /*
         * success
         */
        if ((iov_iter_rw(iter) == WRITE &&
             (!map_data || !map_data->null_mapped)) ||
            (map_data && map_data->from_user)) {
                ret = bio_copy_from_iter(bio, iter);
                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;
        if (map_data && map_data->null_mapped)
                bio_set_flag(bio, BIO_NULL_MAPPED);
        return bio;
cleanup:
        if (!map_data)
                bio_free_pages(bio);
        bio_put(bio);
out_bmd:
        kfree(bmd);
        return ERR_PTR(ret);
}

/**
 *      bio_map_user_iov - map user iovec into bio
 *      @q:             the struct request_queue for the bio
 *      @iter:          iovec iterator
 *      @gfp_mask:      memory allocation flags
 *
 *      Map the user space address into a bio suitable for io to a block
 *      device. Returns an error pointer in case of error.
 */
static struct bio *bio_map_user_iov(struct request_queue *q,
                struct iov_iter *iter, gfp_t gfp_mask)
{
        unsigned int max_sectors = queue_max_hw_sectors(q);
        int j;
        struct bio *bio;
        int ret;

        if (!iov_iter_count(iter))
                return ERR_PTR(-EINVAL);

        bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_PAGES));
        if (!bio)
                return ERR_PTR(-ENOMEM);

        while (iov_iter_count(iter)) {
                struct page **pages;
                ssize_t bytes;
                size_t offs, added = 0;
                int npages;

                bytes = iov_iter_get_pages_alloc(iter, &pages, LONG_MAX, &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(q))) {
                        ret = -EINVAL;
                        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(q, bio, page, n, offs,
                                                     max_sectors, &same_page)) {
                                        if (same_page)
                                                put_page(page);
                                        break;
                                }

                                added += n;
                                bytes -= n;
                                offs = 0;
                        }
                        iov_iter_advance(iter, added);
                }
                /*
                 * release the pages we didn't map into the bio, if any
                 */
                while (j < npages)
                        put_page(pages[j++]);
                kvfree(pages);
                /* couldn't stuff something into bio? */
                if (bytes)
                        break;
        }

        bio_set_flag(bio, BIO_USER_MAPPED);

        /*
         * subtle -- if bio_map_user_iov() ended up bouncing a bio,
         * it would normally disappear when its bi_end_io is run.
         * however, we need it for the unmap, so grab an extra
         * reference to it
         */
        bio_get(bio);
        return bio;

 out_unmap:
        bio_release_pages(bio, false);
        bio_put(bio);
        return ERR_PTR(ret);
}

/**
 *      bio_unmap_user  -       unmap a bio
 *      @bio:           the bio being unmapped
 *
 *      Unmap a bio previously mapped by bio_map_user_iov(). Must be called from
 *      process context.
 *
 *      bio_unmap_user() may sleep.
 */
static void bio_unmap_user(struct bio *bio)
{
        bio_release_pages(bio, bio_data_dir(bio) == READ);
        bio_put(bio);
        bio_put(bio);
}

static void bio_invalidate_vmalloc_pages(struct bio *bio)
{
#ifdef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
        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_put(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(gfp_mask, nr_pages);
        if (!bio)
                return ERR_PTR(-ENOMEM);

        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_put(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_put(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(p, page_address(bvec->bv_page), bvec->bv_len);
                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(gfp_mask, nr_pages);
        if (!bio)
                return ERR_PTR(-ENOMEM);

        while (len) {
                struct page *page;
                unsigned int bytes = PAGE_SIZE;

                if (bytes > len)
                        bytes = len;

                page = alloc_page(q->bounce_gfp | 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_put(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 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;
                bio_crypt_free_ctx(*bio);
        }

        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));

        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;
        struct bio *bio, *orig_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))
                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);

        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);