// 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;
  	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 (!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);
  	bio_put(bio);
  	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, *bounce_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 = 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;

  	bio->bi_opf |= req_op(rq);

  
  	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;

  				goto cleanup;

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

  			page = alloc_page(rq->q->bounce_gfp | 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)) ||
  	    (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;

  
  	bounce_bio = bio;
  	ret = blk_rq_append_bio(rq, &bounce_bio);
  	if (ret)
  		goto cleanup;
  
  	/*
  	 * 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
  	 */
  	bio_get(bounce_bio);
  	return 0;

  cleanup:
  	if (!map_data)
  		bio_free_pages(bio);
  	bio_put(bio);
  out_bmd:
  	kfree(bmd);

  	return ret;

  }

  static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
  		gfp_t gfp_mask)

  {

  	unsigned int max_sectors = queue_max_hw_sectors(rq->q);
  	struct bio *bio, *bounce_bio;

  	int ret;

  	int j;

  
  	if (!iov_iter_count(iter))

  		return -EINVAL;

  
  	bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_PAGES));
  	if (!bio)

  		return -ENOMEM;
  	bio->bi_opf |= req_op(rq);

  
  	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(rq->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(rq->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;
  	}

  	/*

  	 * Subtle: if we end up needing to bounce a bio, it would normally
  	 * disappear when its bi_end_io is run.  However, we need the original
  	 * bio for the unmap, so grab an extra reference to it

  	 */
  	bio_get(bio);

  	bounce_bio = bio;
  	ret = blk_rq_append_bio(rq, &bounce_bio);
  	if (ret)
  		goto out_put_orig;
  
  	/*
  	 * 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
  	 */
  	bio_get(bounce_bio);
  	return 0;
  
   out_put_orig:
  	bio_put(bio);

   out_unmap:
  	bio_release_pages(bio, false);
  	bio_put(bio);

  	return 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);

  /**

   * 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 {

  		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 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;

  		if (bio->bi_private) {

  			ret2 = bio_uncopy_user(mapped_bio);
  			if (ret2 && !ret)
  				ret = ret2;

  		} else {
  			bio_unmap_user(mapped_bio);

  		}

  
  		mapped_bio = bio;
  		bio = bio->bi_next;
  		bio_put(mapped_bio);
  	}
  
  	return ret;
  }

  EXPORT_SYMBOL(blk_rq_unmap_user);

  #ifdef CONFIG_AHCI_IMX
  extern void *sg_io_buffer_hack;
  #else
  #define sg_io_buffer_hack NULL
  #endif

  /**

   * 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;

  #ifdef CONFIG_AHCI_IMX
  	if ((kbuf != sg_io_buffer_hack) && (!blk_rq_aligned(q, addr, len)
  			|| object_is_on_stack(kbuf)))
  #else

  	if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf))

  #endif

  		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);