block/blk-map.c

   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         const struct queue_limits *lim = &rq->q->limits;
 565         unsigned int max_bytes = lim->max_hw_sectors << SECTOR_SHIFT;
 566         unsigned int nsegs;
 567         struct bio *bio;
 568         int ret;
 569
 570         if (!iov_iter_count(iter) || iov_iter_count(iter) > max_bytes)
 571                 return -EINVAL;
 572
 573         /* reuse the bvecs from the iterator instead of allocating new ones */
 574         bio = blk_rq_map_bio_alloc(rq, 0, GFP_KERNEL);
 575         if (!bio)
 576                 return -ENOMEM;
 577         bio_iov_bvec_set(bio, (struct iov_iter *)iter);
 578
 579         /* check that the data layout matches the hardware restrictions */
 580         ret = bio_split_rw_at(bio, lim, &nsegs, max_bytes);
 581         if (ret) {
 582                 /* if we would have to split the bio, copy instead */
 583                 if (ret > 0)
 584                         ret = -EREMOTEIO;
 585                 blk_mq_map_bio_put(bio);
 586                 return ret;
 587         }
 588
 589         blk_rq_bio_prep(rq, bio, nsegs);
 590         return 0;
 591 }
 592
 593 /**
 594  * blk_rq_map_user_iov - map user data to a request, for passthrough requests
 595  * @q:          request queue where request should be inserted
 596  * @rq:         request to map data to
 597  * @map_data:   pointer to the rq_map_data holding pages (if necessary)
 598  * @iter:       iovec iterator
 599  * @gfp_mask:   memory allocation flags
 600  *
 601  * Description:
 602  *    Data will be mapped directly for zero copy I/O, if possible. Otherwise
 603  *    a kernel bounce buffer is used.
 604  *
 605  *    A matching blk_rq_unmap_user() must be issued at the end of I/O, while
 606  *    still in process context.
 607  */
 608 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 609                         struct rq_map_data *map_data,
 610                         const struct iov_iter *iter, gfp_t gfp_mask)
 611 {
 612         bool copy = false, map_bvec = false;
 613         unsigned long align = blk_lim_dma_alignment_and_pad(&q->limits);
 614         struct bio *bio = NULL;
 615         struct iov_iter i;
 616         int ret = -EINVAL;
 617
 618         if (map_data)
 619                 copy = true;
 620         else if (blk_queue_may_bounce(q))
 621                 copy = true;
 622         else if (iov_iter_alignment(iter) & align)
 623                 copy = true;
 624         else if (iov_iter_is_bvec(iter))
 625                 map_bvec = true;
 626         else if (!user_backed_iter(iter))
 627                 copy = true;
 628         else if (queue_virt_boundary(q))
 629                 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
 630
 631         if (map_bvec) {
 632                 ret = blk_rq_map_user_bvec(rq, iter);
 633                 if (!ret)
 634                         return 0;
 635                 if (ret != -EREMOTEIO)
 636                         goto fail;
 637                 /* fall back to copying the data on limits mismatches */
 638                 copy = true;
 639         }
 640
 641         i = *iter;
 642         do {
 643                 if (copy)
 644                         ret = bio_copy_user_iov(rq, map_data, &i, gfp_mask);
 645                 else
 646                         ret = bio_map_user_iov(rq, &i, gfp_mask);
 647                 if (ret)
 648                         goto unmap_rq;
 649                 if (!bio)
 650                         bio = rq->bio;
 651         } while (iov_iter_count(&i));
 652
 653         return 0;
 654
 655 unmap_rq:
 656         blk_rq_unmap_user(bio);
 657 fail:
 658         rq->bio = NULL;
 659         return ret;
 660 }
 661 EXPORT_SYMBOL(blk_rq_map_user_iov);
 662
 663 int blk_rq_map_user(struct request_queue *q, struct request *rq,
 664                     struct rq_map_data *map_data, void __user *ubuf,
 665                     unsigned long len, gfp_t gfp_mask)
 666 {
 667         struct iov_iter i;
 668         int ret = import_ubuf(rq_data_dir(rq), ubuf, len, &i);
 669
 670         if (unlikely(ret < 0))
 671                 return ret;
 672
 673         return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);
 674 }
 675 EXPORT_SYMBOL(blk_rq_map_user);
 676
 677 int blk_rq_map_user_io(struct request *req, struct rq_map_data *map_data,
 678                 void __user *ubuf, unsigned long buf_len, gfp_t gfp_mask,
 679                 bool vec, int iov_count, bool check_iter_count, int rw)
 680 {
 681         int ret = 0;
 682
 683         if (vec) {
 684                 struct iovec fast_iov[UIO_FASTIOV];
 685                 struct iovec *iov = fast_iov;
 686                 struct iov_iter iter;
 687
 688                 ret = import_iovec(rw, ubuf, iov_count ? iov_count : buf_len,
 689                                 UIO_FASTIOV, &iov, &iter);
 690                 if (ret < 0)
 691                         return ret;
 692
 693                 if (iov_count) {
 694                         /* SG_IO howto says that the shorter of the two wins */
 695                         iov_iter_truncate(&iter, buf_len);
 696                         if (check_iter_count && !iov_iter_count(&iter)) {
 697                                 kfree(iov);
 698                                 return -EINVAL;
 699                         }
 700                 }
 701
 702                 ret = blk_rq_map_user_iov(req->q, req, map_data, &iter,
 703                                 gfp_mask);
 704                 kfree(iov);
 705         } else if (buf_len) {
 706                 ret = blk_rq_map_user(req->q, req, map_data, ubuf, buf_len,
 707                                 gfp_mask);
 708         }
 709         return ret;
 710 }
 711 EXPORT_SYMBOL(blk_rq_map_user_io);
 712
 713 /**
 714  * blk_rq_unmap_user - unmap a request with user data
 715  * @bio:               start of bio list
 716  *
 717  * Description:
 718  *    Unmap a rq previously mapped by blk_rq_map_user(). The caller must
 719  *    supply the original rq->bio from the blk_rq_map_user() return, since
 720  *    the I/O completion may have changed rq->bio.
 721  */
 722 int blk_rq_unmap_user(struct bio *bio)
 723 {
 724         struct bio *next_bio;
 725         int ret = 0, ret2;
 726
 727         while (bio) {
 728                 if (bio->bi_private) {
 729                         ret2 = bio_uncopy_user(bio);
 730                         if (ret2 && !ret)
 731                                 ret = ret2;
 732                 } else {
 733                         bio_release_pages(bio, bio_data_dir(bio) == READ);
 734                 }
 735
 736                 if (bio_integrity(bio))
 737                         bio_integrity_unmap_user(bio);
 738
 739                 next_bio = bio;
 740                 bio = bio->bi_next;
 741                 blk_mq_map_bio_put(next_bio);
 742         }
 743
 744         return ret;
 745 }
 746 EXPORT_SYMBOL(blk_rq_unmap_user);
 747
 748 /**
 749  * blk_rq_map_kern - map kernel data to a request, for passthrough requests
 750  * @q:          request queue where request should be inserted
 751  * @rq:         request to fill
 752  * @kbuf:       the kernel buffer
 753  * @len:        length of user data
 754  * @gfp_mask:   memory allocation flags
 755  *
 756  * Description:
 757  *    Data will be mapped directly if possible. Otherwise a bounce
 758  *    buffer is used. Can be called multiple times to append multiple
 759  *    buffers.
 760  */
 761 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 762                     unsigned int len, gfp_t gfp_mask)
 763 {
 764         int reading = rq_data_dir(rq) == READ;
 765         unsigned long addr = (unsigned long) kbuf;
 766         struct bio *bio;
 767         int ret;
 768
 769         if (len > (queue_max_hw_sectors(q) << 9))
 770                 return -EINVAL;
 771         if (!len || !kbuf)
 772                 return -EINVAL;
 773
 774         if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf) ||
 775             blk_queue_may_bounce(q))
 776                 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
 777         else
 778                 bio = bio_map_kern(q, kbuf, len, gfp_mask);
 779
 780         if (IS_ERR(bio))
 781                 return PTR_ERR(bio);
 782
 783         bio->bi_opf &= ~REQ_OP_MASK;
 784         bio->bi_opf |= req_op(rq);
 785
 786         ret = blk_rq_append_bio(rq, bio);
 787         if (unlikely(ret)) {
 788                 bio_uninit(bio);
 789                 kfree(bio);
 790         }
 791         return ret;
 792 }
 793 EXPORT_SYMBOL(blk_rq_map_kern);