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
14 struct 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
21 static 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), gfp_mask);
30 if (!bmd)
31 return NULL;
32 bmd->iter = *data;
33 if (iter_is_iovec(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 */
48 static 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(bvec->bv_page,
57 bvec->bv_offset,
58 bvec->bv_len,
59 iter);
60
61 if (!iov_iter_count(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 */
79 static 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(bvec->bv_page,
88 bvec->bv_offset,
89 bvec->bv_len,
90 &iter);
91
92 if (!iov_iter_count(&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 */
109 static 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, bmd->iter);
124 if (bmd->is_our_pages)
125 bio_free_pages(bio);
126 }
127 kfree(bmd);
128 return ret;
129 }
130
131 static 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(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_pages, gfp_mask);
158 if (!bio)
159 goto out_bmd;
160 bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, req_op(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(iter) == WRITE &&
209 (!map_data || !map_data->null_mapped)) {
210 ret = bio_copy_from_iter(bio, iter);
211 if (ret)
212 goto cleanup;
213 } else if (map_data && map_data->from_user) {
214 struct iov_iter iter2 = *iter;
215
216 /* This is the copy-in part of SG_DXFER_TO_FROM_DEV. */
217 iter2.data_source = ITER_SOURCE;
218 ret = bio_copy_from_iter(bio, &iter2);
219 if (ret)
220 goto cleanup;
221 } else {
222 if (bmd->is_our_pages)
223 zero_fill_bio(bio);
224 iov_iter_advance(iter, bio->bi_iter.bi_size);
225 }
226
227 bio->bi_private = bmd;
228
229 ret = blk_rq_append_bio(rq, bio);
230 if (ret)
231 goto cleanup;
232 return 0;
233 cleanup:
234 if (!map_data)
235 bio_free_pages(bio);
236 bio_uninit(bio);
237 kfree(bio);
238 out_bmd:
239 kfree(bmd);
240 return ret;
241 }
242
243 static void blk_mq_map_bio_put(struct bio *bio)
244 {
245 if (bio->bi_opf & REQ_ALLOC_CACHE) {
246 bio_put(bio);
247 } else {
248 bio_uninit(bio);
249 kfree(bio);
250 }
251 }
252
253 static struct bio *blk_rq_map_bio_alloc(struct request *rq,
254 unsigned int nr_vecs, gfp_t gfp_mask)
255 {
256 struct bio *bio;
257
258 if (rq->cmd_flags & REQ_ALLOC_CACHE && (nr_vecs <= BIO_INLINE_VECS)) {
259 bio = bio_alloc_bioset(NULL, nr_vecs, rq->cmd_flags, gfp_mask,
260 &fs_bio_set);
261 if (!bio)
262 return NULL;
263 } else {
264 bio = bio_kmalloc(nr_vecs, gfp_mask);
265 if (!bio)
266 return NULL;
267 bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs, req_op(rq));
268 }
269 return bio;
270 }
271
272 static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
273 gfp_t gfp_mask)
274 {
275 iov_iter_extraction_t extraction_flags = 0;
276 unsigned int max_sectors = queue_max_hw_sectors(rq->q);
277 unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
278 struct bio *bio;
279 int ret;
280 int j;
281
282 if (!iov_iter_count(iter))
283 return -EINVAL;
284
285 bio = blk_rq_map_bio_alloc(rq, nr_vecs, gfp_mask);
286 if (bio == NULL)
287 return -ENOMEM;
288
289 if (blk_queue_pci_p2pdma(rq->q))
290 extraction_flags |= ITER_ALLOW_P2PDMA;
291 if (iov_iter_extract_will_pin(iter))
292 bio_set_flag(bio, BIO_PAGE_PINNED);
293
294 while (iov_iter_count(iter)) {
295 struct page *stack_pages[UIO_FASTIOV];
296 struct page **pages = stack_pages;
297 ssize_t bytes;
298 size_t offs;
299 int npages;
300
301 if (nr_vecs > ARRAY_SIZE(stack_pages))
302 pages = NULL;
303
304 bytes = iov_iter_extract_pages(iter, &pages, LONG_MAX,
305 nr_vecs, extraction_flags, &offs);
306 if (unlikely(bytes <= 0)) {
307 ret = bytes ? bytes : -EFAULT;
308 goto out_unmap;
309 }
310
311 npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE);
312
313 if (unlikely(offs & queue_dma_alignment(rq->q)))
314 j = 0;
315 else {
316 for (j = 0; j < npages; j++) {
317 struct page *page = pages[j];
318 unsigned int n = PAGE_SIZE - offs;
319 bool same_page = false;
320
321 if (n > bytes)
322 n = bytes;
323
324 if (!bio_add_hw_page(rq->q, bio, page, n, offs,
325 max_sectors, &same_page))
326 break;
327
328 if (same_page)
329 bio_release_page(bio, page);
330 bytes -= n;
331 offs = 0;
332 }
333 }
334 /*
335 * release the pages we didn't map into the bio, if any
336 */
337 while (j < npages)
338 bio_release_page(bio, pages[j++]);
339 if (pages != stack_pages)
340 kvfree(pages);
341 /* couldn't stuff something into bio? */
342 if (bytes) {
343 iov_iter_revert(iter, bytes);
344 break;
345 }
346 }
347
348 ret = blk_rq_append_bio(rq, bio);
349 if (ret)
350 goto out_unmap;
351 return 0;
352
353 out_unmap:
354 bio_release_pages(bio, false);
355 blk_mq_map_bio_put(bio);
356 return ret;
357 }
358
359 static void bio_invalidate_vmalloc_pages(struct bio *bio)
360 {
361 #ifdef ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE
362 if (bio->bi_private && !op_is_write(bio_op(bio))) {
363 unsigned long i, len = 0;
364
365 for (i = 0; i < bio->bi_vcnt; i++)
366 len += bio->bi_io_vec[i].bv_len;
367 invalidate_kernel_vmap_range(bio->bi_private, len);
368 }
369 #endif
370 }
371
372 static void bio_map_kern_endio(struct bio *bio)
373 {
374 bio_invalidate_vmalloc_pages(bio);
375 bio_uninit(bio);
376 kfree(bio);
377 }
378
379 /**
380 * bio_map_kern - map kernel address into bio
381 * @q: the struct request_queue for the bio
382 * @data: pointer to buffer to map
383 * @len: length in bytes
384 * @gfp_mask: allocation flags for bio allocation
385 *
386 * Map the kernel address into a bio suitable for io to a block
387 * device. Returns an error pointer in case of error.
388 */
389 static struct bio *bio_map_kern(struct request_queue *q, void *data,
390 unsigned int len, gfp_t gfp_mask)
391 {
392 unsigned long kaddr = (unsigned long)data;
393 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
394 unsigned long start = kaddr >> PAGE_SHIFT;
395 const int nr_pages = end - start;
396 bool is_vmalloc = is_vmalloc_addr(data);
397 struct page *page;
398 int offset, i;
399 struct bio *bio;
400
401 bio = bio_kmalloc(nr_pages, gfp_mask);
402 if (!bio)
403 return ERR_PTR(-ENOMEM);
404 bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0);
405
406 if (is_vmalloc) {
407 flush_kernel_vmap_range(data, len);
408 bio->bi_private = data;
409 }
410
411 offset = offset_in_page(kaddr);
412 for (i = 0; i < nr_pages; i++) {
413 unsigned int bytes = PAGE_SIZE - offset;
414
415 if (len <= 0)
416 break;
417
418 if (bytes > len)
419 bytes = len;
420
421 if (!is_vmalloc)
422 page = virt_to_page(data);
423 else
424 page = vmalloc_to_page(data);
425 if (bio_add_pc_page(q, bio, page, bytes,
426 offset) < bytes) {
427 /* we don't support partial mappings */
428 bio_uninit(bio);
429 kfree(bio);
430 return ERR_PTR(-EINVAL);
431 }
432
433 data += bytes;
434 len -= bytes;
435 offset = 0;
436 }
437
438 bio->bi_end_io = bio_map_kern_endio;
439 return bio;
440 }
441
442 static void bio_copy_kern_endio(struct bio *bio)
443 {
444 bio_free_pages(bio);
445 bio_uninit(bio);
446 kfree(bio);
447 }
448
449 static void bio_copy_kern_endio_read(struct bio *bio)
450 {
451 char *p = bio->bi_private;
452 struct bio_vec *bvec;
453 struct bvec_iter_all iter_all;
454
455 bio_for_each_segment_all(bvec, bio, iter_all) {
456 memcpy_from_bvec(p, bvec);
457 p += bvec->bv_len;
458 }
459
460 bio_copy_kern_endio(bio);
461 }
462
463 /**
464 * bio_copy_kern - copy kernel address into bio
465 * @q: the struct request_queue for the bio
466 * @data: pointer to buffer to copy
467 * @len: length in bytes
468 * @gfp_mask: allocation flags for bio and page allocation
469 * @reading: data direction is READ
470 *
471 * copy the kernel address into a bio suitable for io to a block
472 * device. Returns an error pointer in case of error.
473 */
474 static struct bio *bio_copy_kern(struct request_queue *q, void *data,
475 unsigned int len, gfp_t gfp_mask, int reading)
476 {
477 unsigned long kaddr = (unsigned long)data;
478 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
479 unsigned long start = kaddr >> PAGE_SHIFT;
480 struct bio *bio;
481 void *p = data;
482 int nr_pages = 0;
483
484 /*
485 * Overflow, abort
486 */
487 if (end < start)
488 return ERR_PTR(-EINVAL);
489
490 nr_pages = end - start;
491 bio = bio_kmalloc(nr_pages, gfp_mask);
492 if (!bio)
493 return ERR_PTR(-ENOMEM);
494 bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0);
495
496 while (len) {
497 struct page *page;
498 unsigned int bytes = PAGE_SIZE;
499
500 if (bytes > len)
501 bytes = len;
502
503 page = alloc_page(GFP_NOIO | __GFP_ZERO | gfp_mask);
504 if (!page)
505 goto cleanup;
506
507 if (!reading)
508 memcpy(page_address(page), p, bytes);
509
510 if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
511 break;
512
513 len -= bytes;
514 p += bytes;
515 }
516
517 if (reading) {
518 bio->bi_end_io = bio_copy_kern_endio_read;
519 bio->bi_private = data;
520 } else {
521 bio->bi_end_io = bio_copy_kern_endio;
522 }
523
524 return bio;
525
526 cleanup:
527 bio_free_pages(bio);
528 bio_uninit(bio);
529 kfree(bio);
530 return ERR_PTR(-ENOMEM);
531 }
532
533 /*
534 * Append a bio to a passthrough request. Only works if the bio can be merged
535 * into the request based on the driver constraints.
536 */
537 int blk_rq_append_bio(struct request *rq, struct bio *bio)
538 {
539 struct bvec_iter iter;
540 struct bio_vec bv;
541 unsigned int nr_segs = 0;
542
543 bio_for_each_bvec(bv, bio, iter)
544 nr_segs++;
545
546 if (!rq->bio) {
547 blk_rq_bio_prep(rq, bio, nr_segs);
548 } else {
549 if (!ll_back_merge_fn(rq, bio, nr_segs))
550 return -EINVAL;
551 rq->biotail->bi_next = bio;
552 rq->biotail = bio;
553 rq->__data_len += (bio)->bi_iter.bi_size;
554 bio_crypt_free_ctx(bio);
555 }
556
557 return 0;
558 }
559 EXPORT_SYMBOL(blk_rq_append_bio);
560
561 /* Prepare bio for passthrough IO given ITER_BVEC iter */
562 static int blk_rq_map_user_bvec(struct request *rq, const struct iov_iter *iter)
563 {
564 struct request_queue *q = rq->q;
565 size_t nr_iter = iov_iter_count(iter);
566 size_t nr_segs = iter->nr_segs;
567 struct bio_vec *bvecs, *bvprvp = NULL;
568 const struct queue_limits *lim = &q->limits;
569 unsigned int nsegs = 0, bytes = 0;
570 struct bio *bio;
571 size_t i;
572
573 if (!nr_iter || (nr_iter >> SECTOR_SHIFT) > queue_max_hw_sectors(q))
574 return -EINVAL;
575 if (nr_segs > queue_max_segments(q))
576 return -EINVAL;
577
578 /* no iovecs to alloc, as we already have a BVEC iterator */
579 bio = blk_rq_map_bio_alloc(rq, 0, GFP_KERNEL);
580 if (bio == NULL)
581 return -ENOMEM;
582
583 bio_iov_bvec_set(bio, (struct iov_iter *)iter);
584 blk_rq_bio_prep(rq, bio, nr_segs);
585
586 /* loop to perform a bunch of sanity checks */
587 bvecs = (struct bio_vec *)iter->bvec;
588 for (i = 0; i < nr_segs; i++) {
589 struct bio_vec *bv = &bvecs[i];
590
591 /*
592 * If the queue doesn't support SG gaps and adding this
593 * offset would create a gap, fallback to copy.
594 */
595 if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv->bv_offset)) {
596 blk_mq_map_bio_put(bio);
597 return -EREMOTEIO;
598 }
599 /* check full condition */
600 if (nsegs >= nr_segs || bytes > UINT_MAX - bv->bv_len)
601 goto put_bio;
602 if (bytes + bv->bv_len > nr_iter)
603 goto put_bio;
604 if (bv->bv_offset + bv->bv_len > PAGE_SIZE)
605 goto put_bio;
606
607 nsegs++;
608 bytes += bv->bv_len;
609 bvprvp = bv;
610 }
611 return 0;
612 put_bio:
613 blk_mq_map_bio_put(bio);
614 return -EINVAL;
615 }
616
617 /**
618 * blk_rq_map_user_iov - map user data to a request, for passthrough requests
619 * @q: request queue where request should be inserted
620 * @rq: request to map data to
621 * @map_data: pointer to the rq_map_data holding pages (if necessary)
622 * @iter: iovec iterator
623 * @gfp_mask: memory allocation flags
624 *
625 * Description:
626 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
627 * a kernel bounce buffer is used.
628 *
629 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
630 * still in process context.
631 */
632 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
633 struct rq_map_data *map_data,
634 const struct iov_iter *iter, gfp_t gfp_mask)
635 {
636 bool copy = false, map_bvec = false;
637 unsigned long align = blk_lim_dma_alignment_and_pad(&q->limits);
638 struct bio *bio = NULL;
639 struct iov_iter i;
640 int ret = -EINVAL;
641
642 if (map_data)
643 copy = true;
644 else if (blk_queue_may_bounce(q))
645 copy = true;
646 else if (iov_iter_alignment(iter) & align)
647 copy = true;
648 else if (iov_iter_is_bvec(iter))
649 map_bvec = true;
650 else if (!user_backed_iter(iter))
651 copy = true;
652 else if (queue_virt_boundary(q))
653 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
654
655 if (map_bvec) {
656 ret = blk_rq_map_user_bvec(rq, iter);
657 if (!ret)
658 return 0;
659 if (ret != -EREMOTEIO)
660 goto fail;
661 /* fall back to copying the data on limits mismatches */
662 copy = true;
663 }
664
665 i = *iter;
666 do {
667 if (copy)
668 ret = bio_copy_user_iov(rq, map_data, &i, gfp_mask);
669 else
670 ret = bio_map_user_iov(rq, &i, gfp_mask);
671 if (ret)
672 goto unmap_rq;
673 if (!bio)
674 bio = rq->bio;
675 } while (iov_iter_count(&i));
676
677 return 0;
678
679 unmap_rq:
680 blk_rq_unmap_user(bio);
681 fail:
682 rq->bio = NULL;
683 return ret;
684 }
685 EXPORT_SYMBOL(blk_rq_map_user_iov);
686
687 int blk_rq_map_user(struct request_queue *q, struct request *rq,
688 struct rq_map_data *map_data, void __user *ubuf,
689 unsigned long len, gfp_t gfp_mask)
690 {
691 struct iov_iter i;
692 int ret = import_ubuf(rq_data_dir(rq), ubuf, len, &i);
693
694 if (unlikely(ret < 0))
695 return ret;
696
697 return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);
698 }
699 EXPORT_SYMBOL(blk_rq_map_user);
700
701 int blk_rq_map_user_io(struct request *req, struct rq_map_data *map_data,
702 void __user *ubuf, unsigned long buf_len, gfp_t gfp_mask,
703 bool vec, int iov_count, bool check_iter_count, int rw)
704 {
705 int ret = 0;
706
707 if (vec) {
708 struct iovec fast_iov[UIO_FASTIOV];
709 struct iovec *iov = fast_iov;
710 struct iov_iter iter;
711
712 ret = import_iovec(rw, ubuf, iov_count ? iov_count : buf_len,
713 UIO_FASTIOV, &iov, &iter);
714 if (ret < 0)
715 return ret;
716
717 if (iov_count) {
718 /* SG_IO howto says that the shorter of the two wins */
719 iov_iter_truncate(&iter, buf_len);
720 if (check_iter_count && !iov_iter_count(&iter)) {
721 kfree(iov);
722 return -EINVAL;
723 }
724 }
725
726 ret = blk_rq_map_user_iov(req->q, req, map_data, &iter,
727 gfp_mask);
728 kfree(iov);
729 } else if (buf_len) {
730 ret = blk_rq_map_user(req->q, req, map_data, ubuf, buf_len,
731 gfp_mask);
732 }
733 return ret;
734 }
735 EXPORT_SYMBOL(blk_rq_map_user_io);
736
737 /**
738 * blk_rq_unmap_user - unmap a request with user data
739 * @bio: start of bio list
740 *
741 * Description:
742 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
743 * supply the original rq->bio from the blk_rq_map_user() return, since
744 * the I/O completion may have changed rq->bio.
745 */
746 int blk_rq_unmap_user(struct bio *bio)
747 {
748 struct bio *next_bio;
749 int ret = 0, ret2;
750
751 while (bio) {
752 if (bio->bi_private) {
753 ret2 = bio_uncopy_user(bio);
754 if (ret2 && !ret)
755 ret = ret2;
756 } else {
757 bio_release_pages(bio, bio_data_dir(bio) == READ);
758 }
759
760 if (bio_integrity(bio))
761 bio_integrity_unmap_user(bio);
762
763 next_bio = bio;
764 bio = bio->bi_next;
765 blk_mq_map_bio_put(next_bio);
766 }
767
768 return ret;
769 }
770 EXPORT_SYMBOL(blk_rq_unmap_user);
771
772 /**
773 * blk_rq_map_kern - map kernel data to a request, for passthrough requests
774 * @q: request queue where request should be inserted
775 * @rq: request to fill
776 * @kbuf: the kernel buffer
777 * @len: length of user data
778 * @gfp_mask: memory allocation flags
779 *
780 * Description:
781 * Data will be mapped directly if possible. Otherwise a bounce
782 * buffer is used. Can be called multiple times to append multiple
783 * buffers.
784 */
785 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
786 unsigned int len, gfp_t gfp_mask)
787 {
788 int reading = rq_data_dir(rq) == READ;
789 unsigned long addr = (unsigned long) kbuf;
790 struct bio *bio;
791 int ret;
792
793 if (len > (queue_max_hw_sectors(q) << 9))
794 return -EINVAL;
795 if (!len || !kbuf)
796 return -EINVAL;
797
798 if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf) ||
799 blk_queue_may_bounce(q))
800 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
801 else
802 bio = bio_map_kern(q, kbuf, len, gfp_mask);
803
804 if (IS_ERR(bio))
805 return PTR_ERR(bio);
806
807 bio->bi_opf &= ~REQ_OP_MASK;
808 bio->bi_opf |= req_op(rq);
809
810 ret = blk_rq_append_bio(rq, bio);
811 if (unlikely(ret)) {
812 bio_uninit(bio);
813 kfree(bio);
814 }
815 return ret;
816 }
817 EXPORT_SYMBOL(blk_rq_map_kern);
818
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