block/fops.c

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