1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE 5 * Copyright (C) 2016 - 2020 Christoph Hellwig 6 */ 7 #include <linux/init.h> 8 #include <linux/mm.h> 9 #include <linux/blkdev.h> 10 #include <linux/buffer_head.h> 11 #include <linux/mpage.h> 12 #include <linux/uio.h> 13 #include <linux/namei.h> 14 #include <linux/task_io_accounting_ops.h> 15 #include <linux/falloc.h> 16 #include <linux/suspend.h> 17 #include <linux/fs.h> 18 #include <linux/module.h> 19 #include "blk.h" 20 21 static inline struct inode *bdev_file_inode(struct file *file) 22 { 23 return file->f_mapping->host; 24 } 25 26 static int blkdev_get_block(struct inode *inode, sector_t iblock, 27 struct buffer_head *bh, int create) 28 { 29 bh->b_bdev = I_BDEV(inode); 30 bh->b_blocknr = iblock; 31 set_buffer_mapped(bh); 32 return 0; 33 } 34 35 static blk_opf_t dio_bio_write_op(struct kiocb *iocb) 36 { 37 blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE; 38 39 /* avoid the need for a I/O completion work item */ 40 if (iocb_is_dsync(iocb)) 41 opf |= REQ_FUA; 42 return opf; 43 } 44 45 static bool blkdev_dio_unaligned(struct block_device *bdev, loff_t pos, 46 struct iov_iter *iter) 47 { 48 return pos & (bdev_logical_block_size(bdev) - 1) || 49 !bdev_iter_is_aligned(bdev, iter); 50 } 51 52 #define DIO_INLINE_BIO_VECS 4 53 54 static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb, 55 struct iov_iter *iter, unsigned int nr_pages) 56 { 57 struct block_device *bdev = iocb->ki_filp->private_data; 58 struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs; 59 loff_t pos = iocb->ki_pos; 60 bool should_dirty = false; 61 struct bio bio; 62 ssize_t ret; 63 64 if (blkdev_dio_unaligned(bdev, pos, iter)) 65 return -EINVAL; 66 67 if (nr_pages <= DIO_INLINE_BIO_VECS) 68 vecs = inline_vecs; 69 else { 70 vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec), 71 GFP_KERNEL); 72 if (!vecs) 73 return -ENOMEM; 74 } 75 76 if (iov_iter_rw(iter) == READ) { 77 bio_init(&bio, bdev, vecs, nr_pages, REQ_OP_READ); 78 if (user_backed_iter(iter)) 79 should_dirty = true; 80 } else { 81 bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb)); 82 } 83 bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT; 84 bio.bi_ioprio = iocb->ki_ioprio; 85 86 ret = bio_iov_iter_get_pages(&bio, iter); 87 if (unlikely(ret)) 88 goto out; 89 ret = bio.bi_iter.bi_size; 90 91 if (iov_iter_rw(iter) == WRITE) 92 task_io_account_write(ret); 93 94 if (iocb->ki_flags & IOCB_NOWAIT) 95 bio.bi_opf |= REQ_NOWAIT; 96 97 submit_bio_wait(&bio); 98 99 bio_release_pages(&bio, should_dirty); 100 if (unlikely(bio.bi_status)) 101 ret = blk_status_to_errno(bio.bi_status); 102 103 out: 104 if (vecs != inline_vecs) 105 kfree(vecs); 106 107 bio_uninit(&bio); 108 109 return ret; 110 } 111 112 enum { 113 DIO_SHOULD_DIRTY = 1, 114 DIO_IS_SYNC = 2, 115 }; 116 117 struct blkdev_dio { 118 union { 119 struct kiocb *iocb; 120 struct task_struct *waiter; 121 }; 122 size_t size; 123 atomic_t ref; 124 unsigned int flags; 125 struct bio bio ____cacheline_aligned_in_smp; 126 }; 127 128 static struct bio_set blkdev_dio_pool; 129 130 static void blkdev_bio_end_io(struct bio *bio) 131 { 132 struct blkdev_dio *dio = bio->bi_private; 133 bool should_dirty = dio->flags & DIO_SHOULD_DIRTY; 134 135 if (bio->bi_status && !dio->bio.bi_status) 136 dio->bio.bi_status = bio->bi_status; 137 138 if (atomic_dec_and_test(&dio->ref)) { 139 if (!(dio->flags & DIO_IS_SYNC)) { 140 struct kiocb *iocb = dio->iocb; 141 ssize_t ret; 142 143 WRITE_ONCE(iocb->private, NULL); 144 145 if (likely(!dio->bio.bi_status)) { 146 ret = dio->size; 147 iocb->ki_pos += ret; 148 } else { 149 ret = blk_status_to_errno(dio->bio.bi_status); 150 } 151 152 dio->iocb->ki_complete(iocb, ret); 153 bio_put(&dio->bio); 154 } else { 155 struct task_struct *waiter = dio->waiter; 156 157 WRITE_ONCE(dio->waiter, NULL); 158 blk_wake_io_task(waiter); 159 } 160 } 161 162 if (should_dirty) { 163 bio_check_pages_dirty(bio); 164 } else { 165 bio_release_pages(bio, false); 166 bio_put(bio); 167 } 168 } 169 170 static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, 171 unsigned int nr_pages) 172 { 173 struct block_device *bdev = iocb->ki_filp->private_data; 174 struct blk_plug plug; 175 struct blkdev_dio *dio; 176 struct bio *bio; 177 bool is_read = (iov_iter_rw(iter) == READ), is_sync; 178 blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb); 179 loff_t pos = iocb->ki_pos; 180 int ret = 0; 181 182 if (blkdev_dio_unaligned(bdev, pos, iter)) 183 return -EINVAL; 184 185 if (iocb->ki_flags & IOCB_ALLOC_CACHE) 186 opf |= REQ_ALLOC_CACHE; 187 bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL, 188 &blkdev_dio_pool); 189 dio = container_of(bio, struct blkdev_dio, bio); 190 atomic_set(&dio->ref, 1); 191 /* 192 * Grab an extra reference to ensure the dio structure which is embedded 193 * into the first bio stays around. 194 */ 195 bio_get(bio); 196 197 is_sync = is_sync_kiocb(iocb); 198 if (is_sync) { 199 dio->flags = DIO_IS_SYNC; 200 dio->waiter = current; 201 } else { 202 dio->flags = 0; 203 dio->iocb = iocb; 204 } 205 206 dio->size = 0; 207 if (is_read && user_backed_iter(iter)) 208 dio->flags |= DIO_SHOULD_DIRTY; 209 210 blk_start_plug(&plug); 211 212 for (;;) { 213 bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT; 214 bio->bi_private = dio; 215 bio->bi_end_io = blkdev_bio_end_io; 216 bio->bi_ioprio = iocb->ki_ioprio; 217 218 ret = bio_iov_iter_get_pages(bio, iter); 219 if (unlikely(ret)) { 220 bio->bi_status = BLK_STS_IOERR; 221 bio_endio(bio); 222 break; 223 } 224 if (iocb->ki_flags & IOCB_NOWAIT) { 225 /* 226 * This is nonblocking IO, and we need to allocate 227 * another bio if we have data left to map. As we 228 * cannot guarantee that one of the sub bios will not 229 * fail getting issued FOR NOWAIT and as error results 230 * are coalesced across all of them, be safe and ask for 231 * a retry of this from blocking context. 232 */ 233 if (unlikely(iov_iter_count(iter))) { 234 bio_release_pages(bio, false); 235 bio_clear_flag(bio, BIO_REFFED); 236 bio_put(bio); 237 blk_finish_plug(&plug); 238 return -EAGAIN; 239 } 240 bio->bi_opf |= REQ_NOWAIT; 241 } 242 243 if (is_read) { 244 if (dio->flags & DIO_SHOULD_DIRTY) 245 bio_set_pages_dirty(bio); 246 } else { 247 task_io_account_write(bio->bi_iter.bi_size); 248 } 249 dio->size += bio->bi_iter.bi_size; 250 pos += bio->bi_iter.bi_size; 251 252 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS); 253 if (!nr_pages) { 254 submit_bio(bio); 255 break; 256 } 257 atomic_inc(&dio->ref); 258 submit_bio(bio); 259 bio = bio_alloc(bdev, nr_pages, opf, GFP_KERNEL); 260 } 261 262 blk_finish_plug(&plug); 263 264 if (!is_sync) 265 return -EIOCBQUEUED; 266 267 for (;;) { 268 set_current_state(TASK_UNINTERRUPTIBLE); 269 if (!READ_ONCE(dio->waiter)) 270 break; 271 blk_io_schedule(); 272 } 273 __set_current_state(TASK_RUNNING); 274 275 if (!ret) 276 ret = blk_status_to_errno(dio->bio.bi_status); 277 if (likely(!ret)) 278 ret = dio->size; 279 280 bio_put(&dio->bio); 281 return ret; 282 } 283 284 static void blkdev_bio_end_io_async(struct bio *bio) 285 { 286 struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio); 287 struct kiocb *iocb = dio->iocb; 288 ssize_t ret; 289 290 WRITE_ONCE(iocb->private, NULL); 291 292 if (likely(!bio->bi_status)) { 293 ret = dio->size; 294 iocb->ki_pos += ret; 295 } else { 296 ret = blk_status_to_errno(bio->bi_status); 297 } 298 299 iocb->ki_complete(iocb, ret); 300 301 if (dio->flags & DIO_SHOULD_DIRTY) { 302 bio_check_pages_dirty(bio); 303 } else { 304 bio_release_pages(bio, false); 305 bio_put(bio); 306 } 307 } 308 309 static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, 310 struct iov_iter *iter, 311 unsigned int nr_pages) 312 { 313 struct block_device *bdev = iocb->ki_filp->private_data; 314 bool is_read = iov_iter_rw(iter) == READ; 315 blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb); 316 struct blkdev_dio *dio; 317 struct bio *bio; 318 loff_t pos = iocb->ki_pos; 319 int ret = 0; 320 321 if (blkdev_dio_unaligned(bdev, pos, iter)) 322 return -EINVAL; 323 324 if (iocb->ki_flags & IOCB_ALLOC_CACHE) 325 opf |= REQ_ALLOC_CACHE; 326 bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL, 327 &blkdev_dio_pool); 328 dio = container_of(bio, struct blkdev_dio, bio); 329 dio->flags = 0; 330 dio->iocb = iocb; 331 bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT; 332 bio->bi_end_io = blkdev_bio_end_io_async; 333 bio->bi_ioprio = iocb->ki_ioprio; 334 335 if (iov_iter_is_bvec(iter)) { 336 /* 337 * Users don't rely on the iterator being in any particular 338 * state for async I/O returning -EIOCBQUEUED, hence we can 339 * avoid expensive iov_iter_advance(). Bypass 340 * bio_iov_iter_get_pages() and set the bvec directly. 341 */ 342 bio_iov_bvec_set(bio, iter); 343 } else { 344 ret = bio_iov_iter_get_pages(bio, iter); 345 if (unlikely(ret)) { 346 bio_put(bio); 347 return ret; 348 } 349 } 350 dio->size = bio->bi_iter.bi_size; 351 352 if (is_read) { 353 if (user_backed_iter(iter)) { 354 dio->flags |= DIO_SHOULD_DIRTY; 355 bio_set_pages_dirty(bio); 356 } 357 } else { 358 task_io_account_write(bio->bi_iter.bi_size); 359 } 360 361 if (iocb->ki_flags & IOCB_HIPRI) { 362 bio->bi_opf |= REQ_POLLED | REQ_NOWAIT; 363 submit_bio(bio); 364 WRITE_ONCE(iocb->private, bio); 365 } else { 366 if (iocb->ki_flags & IOCB_NOWAIT) 367 bio->bi_opf |= REQ_NOWAIT; 368 submit_bio(bio); 369 } 370 return -EIOCBQUEUED; 371 } 372 373 static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 374 { 375 unsigned int nr_pages; 376 377 if (!iov_iter_count(iter)) 378 return 0; 379 380 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1); 381 if (likely(nr_pages <= BIO_MAX_VECS)) { 382 if (is_sync_kiocb(iocb)) 383 return __blkdev_direct_IO_simple(iocb, iter, nr_pages); 384 return __blkdev_direct_IO_async(iocb, iter, nr_pages); 385 } 386 return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages)); 387 } 388 389 static int blkdev_writepage(struct page *page, struct writeback_control *wbc) 390 { 391 return block_write_full_page(page, blkdev_get_block, wbc); 392 } 393 394 static int blkdev_read_folio(struct file *file, struct folio *folio) 395 { 396 return block_read_full_folio(folio, blkdev_get_block); 397 } 398 399 static void blkdev_readahead(struct readahead_control *rac) 400 { 401 mpage_readahead(rac, blkdev_get_block); 402 } 403 404 static int blkdev_write_begin(struct file *file, struct address_space *mapping, 405 loff_t pos, unsigned len, struct page **pagep, void **fsdata) 406 { 407 return block_write_begin(mapping, pos, len, pagep, blkdev_get_block); 408 } 409 410 static int blkdev_write_end(struct file *file, struct address_space *mapping, 411 loff_t pos, unsigned len, unsigned copied, struct page *page, 412 void *fsdata) 413 { 414 int ret; 415 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata); 416 417 unlock_page(page); 418 put_page(page); 419 420 return ret; 421 } 422 423 const struct address_space_operations def_blk_aops = { 424 .dirty_folio = block_dirty_folio, 425 .invalidate_folio = block_invalidate_folio, 426 .read_folio = blkdev_read_folio, 427 .readahead = blkdev_readahead, 428 .writepage = blkdev_writepage, 429 .write_begin = blkdev_write_begin, 430 .write_end = blkdev_write_end, 431 .direct_IO = blkdev_direct_IO, 432 .migrate_folio = buffer_migrate_folio_norefs, 433 .is_dirty_writeback = buffer_check_dirty_writeback, 434 }; 435 436 /* 437 * for a block special file file_inode(file)->i_size is zero 438 * so we compute the size by hand (just as in block_read/write above) 439 */ 440 static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence) 441 { 442 struct inode *bd_inode = bdev_file_inode(file); 443 loff_t retval; 444 445 inode_lock(bd_inode); 446 retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode)); 447 inode_unlock(bd_inode); 448 return retval; 449 } 450 451 static int blkdev_fsync(struct file *filp, loff_t start, loff_t end, 452 int datasync) 453 { 454 struct block_device *bdev = filp->private_data; 455 int error; 456 457 error = file_write_and_wait_range(filp, start, end); 458 if (error) 459 return error; 460 461 /* 462 * There is no need to serialise calls to blkdev_issue_flush with 463 * i_mutex and doing so causes performance issues with concurrent 464 * O_SYNC writers to a block device. 465 */ 466 error = blkdev_issue_flush(bdev); 467 if (error == -EOPNOTSUPP) 468 error = 0; 469 470 return error; 471 } 472 473 static int blkdev_open(struct inode *inode, struct file *filp) 474 { 475 struct block_device *bdev; 476 477 /* 478 * Preserve backwards compatibility and allow large file access 479 * even if userspace doesn't ask for it explicitly. Some mkfs 480 * binary needs it. We might want to drop this workaround 481 * during an unstable branch. 482 */ 483 filp->f_flags |= O_LARGEFILE; 484 filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC; 485 486 if (filp->f_flags & O_NDELAY) 487 filp->f_mode |= FMODE_NDELAY; 488 if (filp->f_flags & O_EXCL) 489 filp->f_mode |= FMODE_EXCL; 490 if ((filp->f_flags & O_ACCMODE) == 3) 491 filp->f_mode |= FMODE_WRITE_IOCTL; 492 493 bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp); 494 if (IS_ERR(bdev)) 495 return PTR_ERR(bdev); 496 497 filp->private_data = bdev; 498 filp->f_mapping = bdev->bd_inode->i_mapping; 499 filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping); 500 return 0; 501 } 502 503 static int blkdev_close(struct inode *inode, struct file *filp) 504 { 505 struct block_device *bdev = filp->private_data; 506 507 blkdev_put(bdev, filp->f_mode); 508 return 0; 509 } 510 511 /* 512 * Write data to the block device. Only intended for the block device itself 513 * and the raw driver which basically is a fake block device. 514 * 515 * Does not take i_mutex for the write and thus is not for general purpose 516 * use. 517 */ 518 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from) 519 { 520 struct block_device *bdev = iocb->ki_filp->private_data; 521 struct inode *bd_inode = bdev->bd_inode; 522 loff_t size = bdev_nr_bytes(bdev); 523 struct blk_plug plug; 524 size_t shorted = 0; 525 ssize_t ret; 526 527 if (bdev_read_only(bdev)) 528 return -EPERM; 529 530 if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev)) 531 return -ETXTBSY; 532 533 if (!iov_iter_count(from)) 534 return 0; 535 536 if (iocb->ki_pos >= size) 537 return -ENOSPC; 538 539 if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT) 540 return -EOPNOTSUPP; 541 542 size -= iocb->ki_pos; 543 if (iov_iter_count(from) > size) { 544 shorted = iov_iter_count(from) - size; 545 iov_iter_truncate(from, size); 546 } 547 548 blk_start_plug(&plug); 549 ret = __generic_file_write_iter(iocb, from); 550 if (ret > 0) 551 ret = generic_write_sync(iocb, ret); 552 iov_iter_reexpand(from, iov_iter_count(from) + shorted); 553 blk_finish_plug(&plug); 554 return ret; 555 } 556 557 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to) 558 { 559 struct block_device *bdev = iocb->ki_filp->private_data; 560 loff_t size = bdev_nr_bytes(bdev); 561 loff_t pos = iocb->ki_pos; 562 size_t shorted = 0; 563 ssize_t ret = 0; 564 size_t count; 565 566 if (unlikely(pos + iov_iter_count(to) > size)) { 567 if (pos >= size) 568 return 0; 569 size -= pos; 570 shorted = iov_iter_count(to) - size; 571 iov_iter_truncate(to, size); 572 } 573 574 count = iov_iter_count(to); 575 if (!count) 576 goto reexpand; /* skip atime */ 577 578 if (iocb->ki_flags & IOCB_DIRECT) { 579 struct address_space *mapping = iocb->ki_filp->f_mapping; 580 581 if (iocb->ki_flags & IOCB_NOWAIT) { 582 if (filemap_range_needs_writeback(mapping, pos, 583 pos + count - 1)) { 584 ret = -EAGAIN; 585 goto reexpand; 586 } 587 } else { 588 ret = filemap_write_and_wait_range(mapping, pos, 589 pos + count - 1); 590 if (ret < 0) 591 goto reexpand; 592 } 593 594 file_accessed(iocb->ki_filp); 595 596 ret = blkdev_direct_IO(iocb, to); 597 if (ret >= 0) { 598 iocb->ki_pos += ret; 599 count -= ret; 600 } 601 iov_iter_revert(to, count - iov_iter_count(to)); 602 if (ret < 0 || !count) 603 goto reexpand; 604 } 605 606 ret = filemap_read(iocb, to, ret); 607 608 reexpand: 609 if (unlikely(shorted)) 610 iov_iter_reexpand(to, iov_iter_count(to) + shorted); 611 return ret; 612 } 613 614 #define BLKDEV_FALLOC_FL_SUPPORTED \ 615 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \ 616 FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE) 617 618 static long blkdev_fallocate(struct file *file, int mode, loff_t start, 619 loff_t len) 620 { 621 struct inode *inode = bdev_file_inode(file); 622 struct block_device *bdev = I_BDEV(inode); 623 loff_t end = start + len - 1; 624 loff_t isize; 625 int error; 626 627 /* Fail if we don't recognize the flags. */ 628 if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED) 629 return -EOPNOTSUPP; 630 631 /* Don't go off the end of the device. */ 632 isize = bdev_nr_bytes(bdev); 633 if (start >= isize) 634 return -EINVAL; 635 if (end >= isize) { 636 if (mode & FALLOC_FL_KEEP_SIZE) { 637 len = isize - start; 638 end = start + len - 1; 639 } else 640 return -EINVAL; 641 } 642 643 /* 644 * Don't allow IO that isn't aligned to logical block size. 645 */ 646 if ((start | len) & (bdev_logical_block_size(bdev) - 1)) 647 return -EINVAL; 648 649 filemap_invalidate_lock(inode->i_mapping); 650 651 /* Invalidate the page cache, including dirty pages. */ 652 error = truncate_bdev_range(bdev, file->f_mode, start, end); 653 if (error) 654 goto fail; 655 656 switch (mode) { 657 case FALLOC_FL_ZERO_RANGE: 658 case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE: 659 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT, 660 len >> SECTOR_SHIFT, GFP_KERNEL, 661 BLKDEV_ZERO_NOUNMAP); 662 break; 663 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE: 664 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT, 665 len >> SECTOR_SHIFT, GFP_KERNEL, 666 BLKDEV_ZERO_NOFALLBACK); 667 break; 668 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE: 669 error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT, 670 len >> SECTOR_SHIFT, GFP_KERNEL); 671 break; 672 default: 673 error = -EOPNOTSUPP; 674 } 675 676 fail: 677 filemap_invalidate_unlock(inode->i_mapping); 678 return error; 679 } 680 681 const struct file_operations def_blk_fops = { 682 .open = blkdev_open, 683 .release = blkdev_close, 684 .llseek = blkdev_llseek, 685 .read_iter = blkdev_read_iter, 686 .write_iter = blkdev_write_iter, 687 .iopoll = iocb_bio_iopoll, 688 .mmap = generic_file_mmap, 689 .fsync = blkdev_fsync, 690 .unlocked_ioctl = blkdev_ioctl, 691 #ifdef CONFIG_COMPAT 692 .compat_ioctl = compat_blkdev_ioctl, 693 #endif 694 .splice_read = generic_file_splice_read, 695 .splice_write = iter_file_splice_write, 696 .fallocate = blkdev_fallocate, 697 }; 698 699 static __init int blkdev_init(void) 700 { 701 return bioset_init(&blkdev_dio_pool, 4, 702 offsetof(struct blkdev_dio, bio), 703 BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE); 704 } 705 module_init(blkdev_init); 706