1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Functions related to mapping data to requests
4 */
5#include <linux/kernel.h>
6#include <linux/sched/task_stack.h>
7#include <linux/module.h>
8#include <linux/bio.h>
9#include <linux/blkdev.h>
10#include <linux/uio.h>
11
12#include "blk.h"
13
14struct bio_map_data {
15 bool is_our_pages : 1;
16 bool is_null_mapped : 1;
17 struct iov_iter iter;
18 struct iovec iov[];
19};
20
21static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data,
22 gfp_t gfp_mask)
23{
24 struct bio_map_data *bmd;
25
26 if (data->nr_segs > UIO_MAXIOV)
27 return NULL;
28
29 bmd = kmalloc(struct_size(bmd, iov, data->nr_segs), flags: gfp_mask);
30 if (!bmd)
31 return NULL;
32 bmd->iter = *data;
33 if (iter_is_iovec(i: data)) {
34 memcpy(bmd->iov, iter_iov(data), sizeof(struct iovec) * data->nr_segs);
35 bmd->iter.__iov = bmd->iov;
36 }
37 return bmd;
38}
39
40/**
41 * bio_copy_from_iter - copy all pages from iov_iter to bio
42 * @bio: The &struct bio which describes the I/O as destination
43 * @iter: iov_iter as source
44 *
45 * Copy all pages from iov_iter to bio.
46 * Returns 0 on success, or error on failure.
47 */
48static int bio_copy_from_iter(struct bio *bio, struct iov_iter *iter)
49{
50 struct bio_vec *bvec;
51 struct bvec_iter_all iter_all;
52
53 bio_for_each_segment_all(bvec, bio, iter_all) {
54 ssize_t ret;
55
56 ret = copy_page_from_iter(page: bvec->bv_page,
57 offset: bvec->bv_offset,
58 bytes: bvec->bv_len,
59 i: iter);
60
61 if (!iov_iter_count(i: iter))
62 break;
63
64 if (ret < bvec->bv_len)
65 return -EFAULT;
66 }
67
68 return 0;
69}
70
71/**
72 * bio_copy_to_iter - copy all pages from bio to iov_iter
73 * @bio: The &struct bio which describes the I/O as source
74 * @iter: iov_iter as destination
75 *
76 * Copy all pages from bio to iov_iter.
77 * Returns 0 on success, or error on failure.
78 */
79static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter)
80{
81 struct bio_vec *bvec;
82 struct bvec_iter_all iter_all;
83
84 bio_for_each_segment_all(bvec, bio, iter_all) {
85 ssize_t ret;
86
87 ret = copy_page_to_iter(page: bvec->bv_page,
88 offset: bvec->bv_offset,
89 bytes: bvec->bv_len,
90 i: &iter);
91
92 if (!iov_iter_count(i: &iter))
93 break;
94
95 if (ret < bvec->bv_len)
96 return -EFAULT;
97 }
98
99 return 0;
100}
101
102/**
103 * bio_uncopy_user - finish previously mapped bio
104 * @bio: bio being terminated
105 *
106 * Free pages allocated from bio_copy_user_iov() and write back data
107 * to user space in case of a read.
108 */
109static int bio_uncopy_user(struct bio *bio)
110{
111 struct bio_map_data *bmd = bio->bi_private;
112 int ret = 0;
113
114 if (!bmd->is_null_mapped) {
115 /*
116 * if we're in a workqueue, the request is orphaned, so
117 * don't copy into a random user address space, just free
118 * and return -EINTR so user space doesn't expect any data.
119 */
120 if (!current->mm)
121 ret = -EINTR;
122 else if (bio_data_dir(bio) == READ)
123 ret = bio_copy_to_iter(bio, iter: bmd->iter);
124 if (bmd->is_our_pages)
125 bio_free_pages(bio);
126 }
127 kfree(objp: bmd);
128 return ret;
129}
130
131static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
132 struct iov_iter *iter, gfp_t gfp_mask)
133{
134 struct bio_map_data *bmd;
135 struct page *page;
136 struct bio *bio;
137 int i = 0, ret;
138 int nr_pages;
139 unsigned int len = iter->count;
140 unsigned int offset = map_data ? offset_in_page(map_data->offset) : 0;
141
142 bmd = bio_alloc_map_data(data: iter, gfp_mask);
143 if (!bmd)
144 return -ENOMEM;
145
146 /*
147 * We need to do a deep copy of the iov_iter including the iovecs.
148 * The caller provided iov might point to an on-stack or otherwise
149 * shortlived one.
150 */
151 bmd->is_our_pages = !map_data;
152 bmd->is_null_mapped = (map_data && map_data->null_mapped);
153
154 nr_pages = bio_max_segs(DIV_ROUND_UP(offset + len, PAGE_SIZE));
155
156 ret = -ENOMEM;
157 bio = bio_kmalloc(nr_vecs: nr_pages, gfp_mask);
158 if (!bio)
159 goto out_bmd;
160 bio_init(bio, NULL, table: bio->bi_inline_vecs, max_vecs: nr_pages, opf: req_op(req: rq));
161
162 if (map_data) {
163 nr_pages = 1U << map_data->page_order;
164 i = map_data->offset / PAGE_SIZE;
165 }
166 while (len) {
167 unsigned int bytes = PAGE_SIZE;
168
169 bytes -= offset;
170
171 if (bytes > len)
172 bytes = len;
173
174 if (map_data) {
175 if (i == map_data->nr_entries * nr_pages) {
176 ret = -ENOMEM;
177 goto cleanup;
178 }
179
180 page = map_data->pages[i / nr_pages];
181 page += (i % nr_pages);
182
183 i++;
184 } else {
185 page = alloc_page(GFP_NOIO | gfp_mask);
186 if (!page) {
187 ret = -ENOMEM;
188 goto cleanup;
189 }
190 }
191
192 if (bio_add_pc_page(rq->q, bio, page, bytes, offset) < bytes) {
193 if (!map_data)
194 __free_page(page);
195 break;
196 }
197
198 len -= bytes;
199 offset = 0;
200 }
201
202 if (map_data)
203 map_data->offset += bio->bi_iter.bi_size;
204
205 /*
206 * success
207 */
208 if ((iov_iter_rw(i: iter) == WRITE &&
209 (!map_data || !map_data->null_mapped)) ||
210 (map_data && map_data->from_user)) {
211 ret = bio_copy_from_iter(bio, iter);
212 if (ret)
213 goto cleanup;
214 } else {
215 if (bmd->is_our_pages)
216 zero_fill_bio(bio);
217 iov_iter_advance(i: iter, bytes: bio->bi_iter.bi_size);
218 }
219
220 bio->bi_private = bmd;
221
222 ret = blk_rq_append_bio(rq, bio);
223 if (ret)
224 goto cleanup;
225 return 0;
226cleanup:
227 if (!map_data)
228 bio_free_pages(bio);
229 bio_uninit(bio);
230 kfree(objp: bio);
231out_bmd:
232 kfree(objp: bmd);
233 return ret;
234}
235
236static void blk_mq_map_bio_put(struct bio *bio)
237{
238 if (bio->bi_opf & REQ_ALLOC_CACHE) {
239 bio_put(bio);
240 } else {
241 bio_uninit(bio);
242 kfree(objp: bio);
243 }
244}
245
246static struct bio *blk_rq_map_bio_alloc(struct request *rq,
247 unsigned int nr_vecs, gfp_t gfp_mask)
248{
249 struct bio *bio;
250
251 if (rq->cmd_flags & REQ_ALLOC_CACHE && (nr_vecs <= BIO_INLINE_VECS)) {
252 bio = bio_alloc_bioset(NULL, nr_vecs, opf: rq->cmd_flags, gfp_mask,
253 bs: &fs_bio_set);
254 if (!bio)
255 return NULL;
256 } else {
257 bio = bio_kmalloc(nr_vecs, gfp_mask);
258 if (!bio)
259 return NULL;
260 bio_init(bio, NULL, table: bio->bi_inline_vecs, max_vecs: nr_vecs, opf: req_op(req: rq));
261 }
262 return bio;
263}
264
265static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
266 gfp_t gfp_mask)
267{
268 iov_iter_extraction_t extraction_flags = 0;
269 unsigned int max_sectors = queue_max_hw_sectors(q: rq->q);
270 unsigned int nr_vecs = iov_iter_npages(i: iter, BIO_MAX_VECS);
271 struct bio *bio;
272 int ret;
273 int j;
274
275 if (!iov_iter_count(i: iter))
276 return -EINVAL;
277
278 bio = blk_rq_map_bio_alloc(rq, nr_vecs, gfp_mask);
279 if (bio == NULL)
280 return -ENOMEM;
281
282 if (blk_queue_pci_p2pdma(rq->q))
283 extraction_flags |= ITER_ALLOW_P2PDMA;
284 if (iov_iter_extract_will_pin(iter))
285 bio_set_flag(bio, bit: BIO_PAGE_PINNED);
286
287 while (iov_iter_count(i: iter)) {
288 struct page *stack_pages[UIO_FASTIOV];
289 struct page **pages = stack_pages;
290 ssize_t bytes;
291 size_t offs;
292 int npages;
293
294 if (nr_vecs > ARRAY_SIZE(stack_pages))
295 pages = NULL;
296
297 bytes = iov_iter_extract_pages(i: iter, pages: &pages, LONG_MAX,
298 maxpages: nr_vecs, extraction_flags, offset0: &offs);
299 if (unlikely(bytes <= 0)) {
300 ret = bytes ? bytes : -EFAULT;
301 goto out_unmap;
302 }
303
304 npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE);
305
306 if (unlikely(offs & queue_dma_alignment(rq->q)))
307 j = 0;
308 else {
309 for (j = 0; j < npages; j++) {
310 struct page *page = pages[j];
311 unsigned int n = PAGE_SIZE - offs;
312 bool same_page = false;
313
314 if (n > bytes)
315 n = bytes;
316
317 if (!bio_add_hw_page(q: rq->q, bio, page, len: n, offset: offs,
318 max_sectors, same_page: &same_page))
319 break;
320
321 if (same_page)
322 bio_release_page(bio, page);
323 bytes -= n;
324 offs = 0;
325 }
326 }
327 /*
328 * release the pages we didn't map into the bio, if any
329 */
330 while (j < npages)
331 bio_release_page(bio, page: pages[j++]);
332 if (pages != stack_pages)
333 kvfree(addr: pages);
334 /* couldn't stuff something into bio? */
335 if (bytes) {
336 iov_iter_revert(i: iter, bytes);
337 break;
338 }
339 }
340
341 ret = blk_rq_append_bio(rq, bio);
342 if (ret)
343 goto out_unmap;
344 return 0;
345
346 out_unmap:
347 bio_release_pages(bio, mark_dirty: false);
348 blk_mq_map_bio_put(bio);
349 return ret;
350}
351
352static void bio_invalidate_vmalloc_pages(struct bio *bio)
353{
354#ifdef ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE
355 if (bio->bi_private && !op_is_write(bio_op(bio))) {
356 unsigned long i, len = 0;
357
358 for (i = 0; i < bio->bi_vcnt; i++)
359 len += bio->bi_io_vec[i].bv_len;
360 invalidate_kernel_vmap_range(bio->bi_private, len);
361 }
362#endif
363}
364
365static void bio_map_kern_endio(struct bio *bio)
366{
367 bio_invalidate_vmalloc_pages(bio);
368 bio_uninit(bio);
369 kfree(objp: bio);
370}
371
372/**
373 * bio_map_kern - map kernel address into bio
374 * @q: the struct request_queue for the bio
375 * @data: pointer to buffer to map
376 * @len: length in bytes
377 * @gfp_mask: allocation flags for bio allocation
378 *
379 * Map the kernel address into a bio suitable for io to a block
380 * device. Returns an error pointer in case of error.
381 */
382static struct bio *bio_map_kern(struct request_queue *q, void *data,
383 unsigned int len, gfp_t gfp_mask)
384{
385 unsigned long kaddr = (unsigned long)data;
386 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
387 unsigned long start = kaddr >> PAGE_SHIFT;
388 const int nr_pages = end - start;
389 bool is_vmalloc = is_vmalloc_addr(x: data);
390 struct page *page;
391 int offset, i;
392 struct bio *bio;
393
394 bio = bio_kmalloc(nr_vecs: nr_pages, gfp_mask);
395 if (!bio)
396 return ERR_PTR(error: -ENOMEM);
397 bio_init(bio, NULL, table: bio->bi_inline_vecs, max_vecs: nr_pages, opf: 0);
398
399 if (is_vmalloc) {
400 flush_kernel_vmap_range(vaddr: data, size: len);
401 bio->bi_private = data;
402 }
403
404 offset = offset_in_page(kaddr);
405 for (i = 0; i < nr_pages; i++) {
406 unsigned int bytes = PAGE_SIZE - offset;
407
408 if (len <= 0)
409 break;
410
411 if (bytes > len)
412 bytes = len;
413
414 if (!is_vmalloc)
415 page = virt_to_page(data);
416 else
417 page = vmalloc_to_page(addr: data);
418 if (bio_add_pc_page(q, bio, page, bytes,
419 offset) < bytes) {
420 /* we don't support partial mappings */
421 bio_uninit(bio);
422 kfree(objp: bio);
423 return ERR_PTR(error: -EINVAL);
424 }
425
426 data += bytes;
427 len -= bytes;
428 offset = 0;
429 }
430
431 bio->bi_end_io = bio_map_kern_endio;
432 return bio;
433}
434
435static void bio_copy_kern_endio(struct bio *bio)
436{
437 bio_free_pages(bio);
438 bio_uninit(bio);
439 kfree(objp: bio);
440}
441
442static void bio_copy_kern_endio_read(struct bio *bio)
443{
444 char *p = bio->bi_private;
445 struct bio_vec *bvec;
446 struct bvec_iter_all iter_all;
447
448 bio_for_each_segment_all(bvec, bio, iter_all) {
449 memcpy_from_bvec(to: p, bvec);
450 p += bvec->bv_len;
451 }
452
453 bio_copy_kern_endio(bio);
454}
455
456/**
457 * bio_copy_kern - copy kernel address into bio
458 * @q: the struct request_queue for the bio
459 * @data: pointer to buffer to copy
460 * @len: length in bytes
461 * @gfp_mask: allocation flags for bio and page allocation
462 * @reading: data direction is READ
463 *
464 * copy the kernel address into a bio suitable for io to a block
465 * device. Returns an error pointer in case of error.
466 */
467static struct bio *bio_copy_kern(struct request_queue *q, void *data,
468 unsigned int len, gfp_t gfp_mask, int reading)
469{
470 unsigned long kaddr = (unsigned long)data;
471 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
472 unsigned long start = kaddr >> PAGE_SHIFT;
473 struct bio *bio;
474 void *p = data;
475 int nr_pages = 0;
476
477 /*
478 * Overflow, abort
479 */
480 if (end < start)
481 return ERR_PTR(error: -EINVAL);
482
483 nr_pages = end - start;
484 bio = bio_kmalloc(nr_vecs: nr_pages, gfp_mask);
485 if (!bio)
486 return ERR_PTR(error: -ENOMEM);
487 bio_init(bio, NULL, table: bio->bi_inline_vecs, max_vecs: nr_pages, opf: 0);
488
489 while (len) {
490 struct page *page;
491 unsigned int bytes = PAGE_SIZE;
492
493 if (bytes > len)
494 bytes = len;
495
496 page = alloc_page(GFP_NOIO | __GFP_ZERO | gfp_mask);
497 if (!page)
498 goto cleanup;
499
500 if (!reading)
501 memcpy(page_address(page), p, bytes);
502
503 if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
504 break;
505
506 len -= bytes;
507 p += bytes;
508 }
509
510 if (reading) {
511 bio->bi_end_io = bio_copy_kern_endio_read;
512 bio->bi_private = data;
513 } else {
514 bio->bi_end_io = bio_copy_kern_endio;
515 }
516
517 return bio;
518
519cleanup:
520 bio_free_pages(bio);
521 bio_uninit(bio);
522 kfree(objp: bio);
523 return ERR_PTR(error: -ENOMEM);
524}
525
526/*
527 * Append a bio to a passthrough request. Only works if the bio can be merged
528 * into the request based on the driver constraints.
529 */
530int blk_rq_append_bio(struct request *rq, struct bio *bio)
531{
532 struct bvec_iter iter;
533 struct bio_vec bv;
534 unsigned int nr_segs = 0;
535
536 bio_for_each_bvec(bv, bio, iter)
537 nr_segs++;
538
539 if (!rq->bio) {
540 blk_rq_bio_prep(rq, bio, nr_segs);
541 } else {
542 if (!ll_back_merge_fn(req: rq, bio, nr_segs))
543 return -EINVAL;
544 rq->biotail->bi_next = bio;
545 rq->biotail = bio;
546 rq->__data_len += (bio)->bi_iter.bi_size;
547 bio_crypt_free_ctx(bio);
548 }
549
550 return 0;
551}
552EXPORT_SYMBOL(blk_rq_append_bio);
553
554/* Prepare bio for passthrough IO given ITER_BVEC iter */
555static int blk_rq_map_user_bvec(struct request *rq, const struct iov_iter *iter)
556{
557 struct request_queue *q = rq->q;
558 size_t nr_iter = iov_iter_count(i: iter);
559 size_t nr_segs = iter->nr_segs;
560 struct bio_vec *bvecs, *bvprvp = NULL;
561 const struct queue_limits *lim = &q->limits;
562 unsigned int nsegs = 0, bytes = 0;
563 struct bio *bio;
564 size_t i;
565
566 if (!nr_iter || (nr_iter >> SECTOR_SHIFT) > queue_max_hw_sectors(q))
567 return -EINVAL;
568 if (nr_segs > queue_max_segments(q))
569 return -EINVAL;
570
571 /* no iovecs to alloc, as we already have a BVEC iterator */
572 bio = blk_rq_map_bio_alloc(rq, nr_vecs: 0, GFP_KERNEL);
573 if (bio == NULL)
574 return -ENOMEM;
575
576 bio_iov_bvec_set(bio, iter: (struct iov_iter *)iter);
577 blk_rq_bio_prep(rq, bio, nr_segs);
578
579 /* loop to perform a bunch of sanity checks */
580 bvecs = (struct bio_vec *)iter->bvec;
581 for (i = 0; i < nr_segs; i++) {
582 struct bio_vec *bv = &bvecs[i];
583
584 /*
585 * If the queue doesn't support SG gaps and adding this
586 * offset would create a gap, fallback to copy.
587 */
588 if (bvprvp && bvec_gap_to_prev(lim, bprv: bvprvp, offset: bv->bv_offset)) {
589 blk_mq_map_bio_put(bio);
590 return -EREMOTEIO;
591 }
592 /* check full condition */
593 if (nsegs >= nr_segs || bytes > UINT_MAX - bv->bv_len)
594 goto put_bio;
595 if (bytes + bv->bv_len > nr_iter)
596 goto put_bio;
597 if (bv->bv_offset + bv->bv_len > PAGE_SIZE)
598 goto put_bio;
599
600 nsegs++;
601 bytes += bv->bv_len;
602 bvprvp = bv;
603 }
604 return 0;
605put_bio:
606 blk_mq_map_bio_put(bio);
607 return -EINVAL;
608}
609
610/**
611 * blk_rq_map_user_iov - map user data to a request, for passthrough requests
612 * @q: request queue where request should be inserted
613 * @rq: request to map data to
614 * @map_data: pointer to the rq_map_data holding pages (if necessary)
615 * @iter: iovec iterator
616 * @gfp_mask: memory allocation flags
617 *
618 * Description:
619 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
620 * a kernel bounce buffer is used.
621 *
622 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
623 * still in process context.
624 */
625int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
626 struct rq_map_data *map_data,
627 const struct iov_iter *iter, gfp_t gfp_mask)
628{
629 bool copy = false, map_bvec = false;
630 unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
631 struct bio *bio = NULL;
632 struct iov_iter i;
633 int ret = -EINVAL;
634
635 if (map_data)
636 copy = true;
637 else if (blk_queue_may_bounce(q))
638 copy = true;
639 else if (iov_iter_alignment(i: iter) & align)
640 copy = true;
641 else if (iov_iter_is_bvec(i: iter))
642 map_bvec = true;
643 else if (!user_backed_iter(i: iter))
644 copy = true;
645 else if (queue_virt_boundary(q))
646 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(i: iter);
647
648 if (map_bvec) {
649 ret = blk_rq_map_user_bvec(rq, iter);
650 if (!ret)
651 return 0;
652 if (ret != -EREMOTEIO)
653 goto fail;
654 /* fall back to copying the data on limits mismatches */
655 copy = true;
656 }
657
658 i = *iter;
659 do {
660 if (copy)
661 ret = bio_copy_user_iov(rq, map_data, iter: &i, gfp_mask);
662 else
663 ret = bio_map_user_iov(rq, iter: &i, gfp_mask);
664 if (ret)
665 goto unmap_rq;
666 if (!bio)
667 bio = rq->bio;
668 } while (iov_iter_count(i: &i));
669
670 return 0;
671
672unmap_rq:
673 blk_rq_unmap_user(bio);
674fail:
675 rq->bio = NULL;
676 return ret;
677}
678EXPORT_SYMBOL(blk_rq_map_user_iov);
679
680int blk_rq_map_user(struct request_queue *q, struct request *rq,
681 struct rq_map_data *map_data, void __user *ubuf,
682 unsigned long len, gfp_t gfp_mask)
683{
684 struct iov_iter i;
685 int ret = import_ubuf(rq_data_dir(rq), buf: ubuf, len, i: &i);
686
687 if (unlikely(ret < 0))
688 return ret;
689
690 return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);
691}
692EXPORT_SYMBOL(blk_rq_map_user);
693
694int blk_rq_map_user_io(struct request *req, struct rq_map_data *map_data,
695 void __user *ubuf, unsigned long buf_len, gfp_t gfp_mask,
696 bool vec, int iov_count, bool check_iter_count, int rw)
697{
698 int ret = 0;
699
700 if (vec) {
701 struct iovec fast_iov[UIO_FASTIOV];
702 struct iovec *iov = fast_iov;
703 struct iov_iter iter;
704
705 ret = import_iovec(type: rw, uvec: ubuf, nr_segs: iov_count ? iov_count : buf_len,
706 UIO_FASTIOV, iovp: &iov, i: &iter);
707 if (ret < 0)
708 return ret;
709
710 if (iov_count) {
711 /* SG_IO howto says that the shorter of the two wins */
712 iov_iter_truncate(i: &iter, count: buf_len);
713 if (check_iter_count && !iov_iter_count(i: &iter)) {
714 kfree(objp: iov);
715 return -EINVAL;
716 }
717 }
718
719 ret = blk_rq_map_user_iov(req->q, req, map_data, &iter,
720 gfp_mask);
721 kfree(objp: iov);
722 } else if (buf_len) {
723 ret = blk_rq_map_user(req->q, req, map_data, ubuf, buf_len,
724 gfp_mask);
725 }
726 return ret;
727}
728EXPORT_SYMBOL(blk_rq_map_user_io);
729
730/**
731 * blk_rq_unmap_user - unmap a request with user data
732 * @bio: start of bio list
733 *
734 * Description:
735 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
736 * supply the original rq->bio from the blk_rq_map_user() return, since
737 * the I/O completion may have changed rq->bio.
738 */
739int blk_rq_unmap_user(struct bio *bio)
740{
741 struct bio *next_bio;
742 int ret = 0, ret2;
743
744 while (bio) {
745 if (bio->bi_private) {
746 ret2 = bio_uncopy_user(bio);
747 if (ret2 && !ret)
748 ret = ret2;
749 } else {
750 bio_release_pages(bio, bio_data_dir(bio) == READ);
751 }
752
753 next_bio = bio;
754 bio = bio->bi_next;
755 blk_mq_map_bio_put(bio: next_bio);
756 }
757
758 return ret;
759}
760EXPORT_SYMBOL(blk_rq_unmap_user);
761
762/**
763 * blk_rq_map_kern - map kernel data to a request, for passthrough requests
764 * @q: request queue where request should be inserted
765 * @rq: request to fill
766 * @kbuf: the kernel buffer
767 * @len: length of user data
768 * @gfp_mask: memory allocation flags
769 *
770 * Description:
771 * Data will be mapped directly if possible. Otherwise a bounce
772 * buffer is used. Can be called multiple times to append multiple
773 * buffers.
774 */
775int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
776 unsigned int len, gfp_t gfp_mask)
777{
778 int reading = rq_data_dir(rq) == READ;
779 unsigned long addr = (unsigned long) kbuf;
780 struct bio *bio;
781 int ret;
782
783 if (len > (queue_max_hw_sectors(q) << 9))
784 return -EINVAL;
785 if (!len || !kbuf)
786 return -EINVAL;
787
788 if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(obj: kbuf) ||
789 blk_queue_may_bounce(q))
790 bio = bio_copy_kern(q, data: kbuf, len, gfp_mask, reading);
791 else
792 bio = bio_map_kern(q, data: kbuf, len, gfp_mask);
793
794 if (IS_ERR(ptr: bio))
795 return PTR_ERR(ptr: bio);
796
797 bio->bi_opf &= ~REQ_OP_MASK;
798 bio->bi_opf |= req_op(req: rq);
799
800 ret = blk_rq_append_bio(rq, bio);
801 if (unlikely(ret)) {
802 bio_uninit(bio);
803 kfree(objp: bio);
804 }
805 return ret;
806}
807EXPORT_SYMBOL(blk_rq_map_kern);
808

source code of linux/block/blk-map.c