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
bio_alloc_map_data(struct iov_iter * data,gfp_t gfp_mask)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 memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs);
33 bmd->iter = *data;
34 bmd->iter.iov = bmd->iov;
35 return bmd;
36 }
37
38 /**
39 * bio_copy_from_iter - copy all pages from iov_iter to bio
40 * @bio: The &struct bio which describes the I/O as destination
41 * @iter: iov_iter as source
42 *
43 * Copy all pages from iov_iter to bio.
44 * Returns 0 on success, or error on failure.
45 */
bio_copy_from_iter(struct bio * bio,struct iov_iter * iter)46 static int bio_copy_from_iter(struct bio *bio, struct iov_iter *iter)
47 {
48 struct bio_vec *bvec;
49 struct bvec_iter_all iter_all;
50
51 bio_for_each_segment_all(bvec, bio, iter_all) {
52 ssize_t ret;
53
54 ret = copy_page_from_iter(bvec->bv_page,
55 bvec->bv_offset,
56 bvec->bv_len,
57 iter);
58
59 if (!iov_iter_count(iter))
60 break;
61
62 if (ret < bvec->bv_len)
63 return -EFAULT;
64 }
65
66 return 0;
67 }
68
69 /**
70 * bio_copy_to_iter - copy all pages from bio to iov_iter
71 * @bio: The &struct bio which describes the I/O as source
72 * @iter: iov_iter as destination
73 *
74 * Copy all pages from bio to iov_iter.
75 * Returns 0 on success, or error on failure.
76 */
bio_copy_to_iter(struct bio * bio,struct iov_iter iter)77 static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter)
78 {
79 struct bio_vec *bvec;
80 struct bvec_iter_all iter_all;
81
82 bio_for_each_segment_all(bvec, bio, iter_all) {
83 ssize_t ret;
84
85 ret = copy_page_to_iter(bvec->bv_page,
86 bvec->bv_offset,
87 bvec->bv_len,
88 &iter);
89
90 if (!iov_iter_count(&iter))
91 break;
92
93 if (ret < bvec->bv_len)
94 return -EFAULT;
95 }
96
97 return 0;
98 }
99
100 /**
101 * bio_uncopy_user - finish previously mapped bio
102 * @bio: bio being terminated
103 *
104 * Free pages allocated from bio_copy_user_iov() and write back data
105 * to user space in case of a read.
106 */
bio_uncopy_user(struct bio * bio)107 static int bio_uncopy_user(struct bio *bio)
108 {
109 struct bio_map_data *bmd = bio->bi_private;
110 int ret = 0;
111
112 if (!bmd->is_null_mapped) {
113 /*
114 * if we're in a workqueue, the request is orphaned, so
115 * don't copy into a random user address space, just free
116 * and return -EINTR so user space doesn't expect any data.
117 */
118 if (!current->mm)
119 ret = -EINTR;
120 else if (bio_data_dir(bio) == READ)
121 ret = bio_copy_to_iter(bio, bmd->iter);
122 if (bmd->is_our_pages)
123 bio_free_pages(bio);
124 }
125 kfree(bmd);
126 return ret;
127 }
128
bio_copy_user_iov(struct request * rq,struct rq_map_data * map_data,struct iov_iter * iter,gfp_t gfp_mask)129 static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
130 struct iov_iter *iter, gfp_t gfp_mask)
131 {
132 struct bio_map_data *bmd;
133 struct page *page;
134 struct bio *bio;
135 int i = 0, ret;
136 int nr_pages;
137 unsigned int len = iter->count;
138 unsigned int offset = map_data ? offset_in_page(map_data->offset) : 0;
139
140 bmd = bio_alloc_map_data(iter, gfp_mask);
141 if (!bmd)
142 return -ENOMEM;
143
144 /*
145 * We need to do a deep copy of the iov_iter including the iovecs.
146 * The caller provided iov might point to an on-stack or otherwise
147 * shortlived one.
148 */
149 bmd->is_our_pages = !map_data;
150 bmd->is_null_mapped = (map_data && map_data->null_mapped);
151
152 nr_pages = bio_max_segs(DIV_ROUND_UP(offset + len, PAGE_SIZE));
153
154 ret = -ENOMEM;
155 bio = bio_kmalloc(gfp_mask, nr_pages);
156 if (!bio)
157 goto out_bmd;
158 bio->bi_opf |= req_op(rq);
159
160 if (map_data) {
161 nr_pages = 1 << map_data->page_order;
162 i = map_data->offset / PAGE_SIZE;
163 }
164 while (len) {
165 unsigned int bytes = PAGE_SIZE;
166
167 bytes -= offset;
168
169 if (bytes > len)
170 bytes = len;
171
172 if (map_data) {
173 if (i == map_data->nr_entries * nr_pages) {
174 ret = -ENOMEM;
175 goto cleanup;
176 }
177
178 page = map_data->pages[i / nr_pages];
179 page += (i % nr_pages);
180
181 i++;
182 } else {
183 page = alloc_page(GFP_NOIO | gfp_mask);
184 if (!page) {
185 ret = -ENOMEM;
186 goto cleanup;
187 }
188 }
189
190 if (bio_add_pc_page(rq->q, bio, page, bytes, offset) < bytes) {
191 if (!map_data)
192 __free_page(page);
193 break;
194 }
195
196 len -= bytes;
197 offset = 0;
198 }
199
200 if (map_data)
201 map_data->offset += bio->bi_iter.bi_size;
202
203 /*
204 * success
205 */
206 if ((iov_iter_rw(iter) == WRITE &&
207 (!map_data || !map_data->null_mapped)) ||
208 (map_data && map_data->from_user)) {
209 ret = bio_copy_from_iter(bio, iter);
210 if (ret)
211 goto cleanup;
212 } else {
213 if (bmd->is_our_pages)
214 zero_fill_bio(bio);
215 iov_iter_advance(iter, bio->bi_iter.bi_size);
216 }
217
218 bio->bi_private = bmd;
219
220 ret = blk_rq_append_bio(rq, bio);
221 if (ret)
222 goto cleanup;
223 return 0;
224 cleanup:
225 if (!map_data)
226 bio_free_pages(bio);
227 bio_put(bio);
228 out_bmd:
229 kfree(bmd);
230 return ret;
231 }
232
bio_map_user_iov(struct request * rq,struct iov_iter * iter,gfp_t gfp_mask)233 static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
234 gfp_t gfp_mask)
235 {
236 unsigned int max_sectors = queue_max_hw_sectors(rq->q);
237 struct bio *bio;
238 int ret;
239 int j;
240
241 if (!iov_iter_count(iter))
242 return -EINVAL;
243
244 bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_VECS));
245 if (!bio)
246 return -ENOMEM;
247 bio->bi_opf |= req_op(rq);
248
249 while (iov_iter_count(iter)) {
250 struct page **pages;
251 ssize_t bytes;
252 size_t offs, added = 0;
253 int npages;
254
255 bytes = iov_iter_get_pages_alloc(iter, &pages, LONG_MAX, &offs);
256 if (unlikely(bytes <= 0)) {
257 ret = bytes ? bytes : -EFAULT;
258 goto out_unmap;
259 }
260
261 npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE);
262
263 if (unlikely(offs & queue_dma_alignment(rq->q))) {
264 ret = -EINVAL;
265 j = 0;
266 } else {
267 for (j = 0; j < npages; j++) {
268 struct page *page = pages[j];
269 unsigned int n = PAGE_SIZE - offs;
270 bool same_page = false;
271
272 if (n > bytes)
273 n = bytes;
274
275 if (!bio_add_hw_page(rq->q, bio, page, n, offs,
276 max_sectors, &same_page)) {
277 if (same_page)
278 put_page(page);
279 break;
280 }
281
282 added += n;
283 bytes -= n;
284 offs = 0;
285 }
286 iov_iter_advance(iter, added);
287 }
288 /*
289 * release the pages we didn't map into the bio, if any
290 */
291 while (j < npages)
292 put_page(pages[j++]);
293 kvfree(pages);
294 /* couldn't stuff something into bio? */
295 if (bytes)
296 break;
297 }
298
299 ret = blk_rq_append_bio(rq, bio);
300 if (ret)
301 goto out_unmap;
302 return 0;
303
304 out_unmap:
305 bio_release_pages(bio, false);
306 bio_put(bio);
307 return ret;
308 }
309
bio_invalidate_vmalloc_pages(struct bio * bio)310 static void bio_invalidate_vmalloc_pages(struct bio *bio)
311 {
312 #ifdef ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE
313 if (bio->bi_private && !op_is_write(bio_op(bio))) {
314 unsigned long i, len = 0;
315
316 for (i = 0; i < bio->bi_vcnt; i++)
317 len += bio->bi_io_vec[i].bv_len;
318 invalidate_kernel_vmap_range(bio->bi_private, len);
319 }
320 #endif
321 }
322
bio_map_kern_endio(struct bio * bio)323 static void bio_map_kern_endio(struct bio *bio)
324 {
325 bio_invalidate_vmalloc_pages(bio);
326 bio_put(bio);
327 }
328
329 /**
330 * bio_map_kern - map kernel address into bio
331 * @q: the struct request_queue for the bio
332 * @data: pointer to buffer to map
333 * @len: length in bytes
334 * @gfp_mask: allocation flags for bio allocation
335 *
336 * Map the kernel address into a bio suitable for io to a block
337 * device. Returns an error pointer in case of error.
338 */
bio_map_kern(struct request_queue * q,void * data,unsigned int len,gfp_t gfp_mask)339 static struct bio *bio_map_kern(struct request_queue *q, void *data,
340 unsigned int len, gfp_t gfp_mask)
341 {
342 unsigned long kaddr = (unsigned long)data;
343 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
344 unsigned long start = kaddr >> PAGE_SHIFT;
345 const int nr_pages = end - start;
346 bool is_vmalloc = is_vmalloc_addr(data);
347 struct page *page;
348 int offset, i;
349 struct bio *bio;
350
351 bio = bio_kmalloc(gfp_mask, nr_pages);
352 if (!bio)
353 return ERR_PTR(-ENOMEM);
354
355 if (is_vmalloc) {
356 flush_kernel_vmap_range(data, len);
357 bio->bi_private = data;
358 }
359
360 offset = offset_in_page(kaddr);
361 for (i = 0; i < nr_pages; i++) {
362 unsigned int bytes = PAGE_SIZE - offset;
363
364 if (len <= 0)
365 break;
366
367 if (bytes > len)
368 bytes = len;
369
370 if (!is_vmalloc)
371 page = virt_to_page(data);
372 else
373 page = vmalloc_to_page(data);
374 if (bio_add_pc_page(q, bio, page, bytes,
375 offset) < bytes) {
376 /* we don't support partial mappings */
377 bio_put(bio);
378 return ERR_PTR(-EINVAL);
379 }
380
381 data += bytes;
382 len -= bytes;
383 offset = 0;
384 }
385
386 bio->bi_end_io = bio_map_kern_endio;
387 return bio;
388 }
389
bio_copy_kern_endio(struct bio * bio)390 static void bio_copy_kern_endio(struct bio *bio)
391 {
392 bio_free_pages(bio);
393 bio_put(bio);
394 }
395
bio_copy_kern_endio_read(struct bio * bio)396 static void bio_copy_kern_endio_read(struct bio *bio)
397 {
398 char *p = bio->bi_private;
399 struct bio_vec *bvec;
400 struct bvec_iter_all iter_all;
401
402 bio_for_each_segment_all(bvec, bio, iter_all) {
403 memcpy_from_bvec(p, bvec);
404 p += bvec->bv_len;
405 }
406
407 bio_copy_kern_endio(bio);
408 }
409
410 /**
411 * bio_copy_kern - copy kernel address into bio
412 * @q: the struct request_queue for the bio
413 * @data: pointer to buffer to copy
414 * @len: length in bytes
415 * @gfp_mask: allocation flags for bio and page allocation
416 * @reading: data direction is READ
417 *
418 * copy the kernel address into a bio suitable for io to a block
419 * device. Returns an error pointer in case of error.
420 */
bio_copy_kern(struct request_queue * q,void * data,unsigned int len,gfp_t gfp_mask,int reading)421 static struct bio *bio_copy_kern(struct request_queue *q, void *data,
422 unsigned int len, gfp_t gfp_mask, int reading)
423 {
424 unsigned long kaddr = (unsigned long)data;
425 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
426 unsigned long start = kaddr >> PAGE_SHIFT;
427 struct bio *bio;
428 void *p = data;
429 int nr_pages = 0;
430
431 /*
432 * Overflow, abort
433 */
434 if (end < start)
435 return ERR_PTR(-EINVAL);
436
437 nr_pages = end - start;
438 bio = bio_kmalloc(gfp_mask, nr_pages);
439 if (!bio)
440 return ERR_PTR(-ENOMEM);
441
442 while (len) {
443 struct page *page;
444 unsigned int bytes = PAGE_SIZE;
445
446 if (bytes > len)
447 bytes = len;
448
449 page = alloc_page(GFP_NOIO | __GFP_ZERO | gfp_mask);
450 if (!page)
451 goto cleanup;
452
453 if (!reading)
454 memcpy(page_address(page), p, bytes);
455
456 if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
457 break;
458
459 len -= bytes;
460 p += bytes;
461 }
462
463 if (reading) {
464 bio->bi_end_io = bio_copy_kern_endio_read;
465 bio->bi_private = data;
466 } else {
467 bio->bi_end_io = bio_copy_kern_endio;
468 }
469
470 return bio;
471
472 cleanup:
473 bio_free_pages(bio);
474 bio_put(bio);
475 return ERR_PTR(-ENOMEM);
476 }
477
478 /*
479 * Append a bio to a passthrough request. Only works if the bio can be merged
480 * into the request based on the driver constraints.
481 */
blk_rq_append_bio(struct request * rq,struct bio * bio)482 int blk_rq_append_bio(struct request *rq, struct bio *bio)
483 {
484 struct bvec_iter iter;
485 struct bio_vec bv;
486 unsigned int nr_segs = 0;
487
488 bio_for_each_bvec(bv, bio, iter)
489 nr_segs += blk_segments(&rq->q->limits, bv.bv_len);
490
491 if (!rq->bio) {
492 blk_rq_bio_prep(rq, bio, nr_segs);
493 } else {
494 if (!ll_back_merge_fn(rq, bio, nr_segs))
495 return -EINVAL;
496 rq->biotail->bi_next = bio;
497 rq->biotail = bio;
498 rq->__data_len += (bio)->bi_iter.bi_size;
499 bio_crypt_free_ctx(bio);
500 }
501
502 return 0;
503 }
504 EXPORT_SYMBOL(blk_rq_append_bio);
505
506 /**
507 * blk_rq_map_user_iov - map user data to a request, for passthrough requests
508 * @q: request queue where request should be inserted
509 * @rq: request to map data to
510 * @map_data: pointer to the rq_map_data holding pages (if necessary)
511 * @iter: iovec iterator
512 * @gfp_mask: memory allocation flags
513 *
514 * Description:
515 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
516 * a kernel bounce buffer is used.
517 *
518 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
519 * still in process context.
520 */
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)521 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
522 struct rq_map_data *map_data,
523 const struct iov_iter *iter, gfp_t gfp_mask)
524 {
525 bool copy = false;
526 unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
527 struct bio *bio = NULL;
528 struct iov_iter i;
529 int ret = -EINVAL;
530
531 if (!iter_is_iovec(iter))
532 goto fail;
533
534 if (map_data)
535 copy = true;
536 else if (blk_queue_may_bounce(q))
537 copy = true;
538 else if (iov_iter_alignment(iter) & align)
539 copy = true;
540 else if (queue_virt_boundary(q))
541 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
542
543 i = *iter;
544 do {
545 if (copy)
546 ret = bio_copy_user_iov(rq, map_data, &i, gfp_mask);
547 else
548 ret = bio_map_user_iov(rq, &i, gfp_mask);
549 if (ret)
550 goto unmap_rq;
551 if (!bio)
552 bio = rq->bio;
553 } while (iov_iter_count(&i));
554
555 return 0;
556
557 unmap_rq:
558 blk_rq_unmap_user(bio);
559 fail:
560 rq->bio = NULL;
561 return ret;
562 }
563 EXPORT_SYMBOL(blk_rq_map_user_iov);
564
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)565 int blk_rq_map_user(struct request_queue *q, struct request *rq,
566 struct rq_map_data *map_data, void __user *ubuf,
567 unsigned long len, gfp_t gfp_mask)
568 {
569 struct iovec iov;
570 struct iov_iter i;
571 int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i);
572
573 if (unlikely(ret < 0))
574 return ret;
575
576 return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);
577 }
578 EXPORT_SYMBOL(blk_rq_map_user);
579
580 /**
581 * blk_rq_unmap_user - unmap a request with user data
582 * @bio: start of bio list
583 *
584 * Description:
585 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
586 * supply the original rq->bio from the blk_rq_map_user() return, since
587 * the I/O completion may have changed rq->bio.
588 */
blk_rq_unmap_user(struct bio * bio)589 int blk_rq_unmap_user(struct bio *bio)
590 {
591 struct bio *next_bio;
592 int ret = 0, ret2;
593
594 while (bio) {
595 if (bio->bi_private) {
596 ret2 = bio_uncopy_user(bio);
597 if (ret2 && !ret)
598 ret = ret2;
599 } else {
600 bio_release_pages(bio, bio_data_dir(bio) == READ);
601 }
602
603 next_bio = bio;
604 bio = bio->bi_next;
605 bio_put(next_bio);
606 }
607
608 return ret;
609 }
610 EXPORT_SYMBOL(blk_rq_unmap_user);
611
612 /**
613 * blk_rq_map_kern - map kernel data to a request, for passthrough requests
614 * @q: request queue where request should be inserted
615 * @rq: request to fill
616 * @kbuf: the kernel buffer
617 * @len: length of user data
618 * @gfp_mask: memory allocation flags
619 *
620 * Description:
621 * Data will be mapped directly if possible. Otherwise a bounce
622 * buffer is used. Can be called multiple times to append multiple
623 * buffers.
624 */
blk_rq_map_kern(struct request_queue * q,struct request * rq,void * kbuf,unsigned int len,gfp_t gfp_mask)625 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
626 unsigned int len, gfp_t gfp_mask)
627 {
628 int reading = rq_data_dir(rq) == READ;
629 unsigned long addr = (unsigned long) kbuf;
630 struct bio *bio;
631 int ret;
632
633 if (len > (queue_max_hw_sectors(q) << 9))
634 return -EINVAL;
635 if (!len || !kbuf)
636 return -EINVAL;
637
638 if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf) ||
639 blk_queue_may_bounce(q))
640 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
641 else
642 bio = bio_map_kern(q, kbuf, len, gfp_mask);
643
644 if (IS_ERR(bio))
645 return PTR_ERR(bio);
646
647 bio->bi_opf &= ~REQ_OP_MASK;
648 bio->bi_opf |= req_op(rq);
649
650 ret = blk_rq_append_bio(rq, bio);
651 if (unlikely(ret))
652 bio_put(bio);
653 return ret;
654 }
655 EXPORT_SYMBOL(blk_rq_map_kern);
656