Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 805 insertions, 0 deletions

diff --git a/block/blk-map.c b/block/blk-map.c
new file mode 100644
index 000000000..66da9e2b1
--- /dev/null
+++ b/block/blk-map.c
@@ -0,0 +1,805 @@
+// 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);
+	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)) ||
+	    (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;
+
+	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_POLLED && (nr_vecs <= BIO_INLINE_VECS)) {
+		blk_opf_t opf = rq->cmd_flags | REQ_ALLOC_CACHE;
+
+		bio = bio_alloc_bioset(NULL, nr_vecs, opf, 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)
+{
+	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;
+
+	while (iov_iter_count(iter)) {
+		struct page **pages, *stack_pages[UIO_FASTIOV];
+		ssize_t bytes;
+		size_t offs;
+		int npages;
+
+		if (nr_vecs <= ARRAY_SIZE(stack_pages)) {
+			pages = stack_pages;
+			bytes = iov_iter_get_pages2(iter, pages, LONG_MAX,
+							nr_vecs, &offs);
+		} else {
+			bytes = iov_iter_get_pages_alloc2(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)))
+			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;
+				}
+
+				bytes -= n;
+				offs = 0;
+			}
+		}
+		/*
+		 * release the pages we didn't map into the bio, if any
+		 */
+		while (j < npages)
+			put_page(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;
+	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 = q->dma_pad_mask | queue_dma_alignment(q);
+	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 (!iter_is_iovec(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 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);
+
+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);
+		}
+
+		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);