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 <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 = I_BDEV(iocb->ki_filp->f_mapping->host);
  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 = I_BDEV(iocb->ki_filp->f_mapping->host);
 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 = I_BDEV(iocb->ki_filp->f_mapping->host);
 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 = I_BDEV(filp->f_mapping->host);
 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 blk_mode_t file_to_blk_mode(struct file *file)
 474 {
 475         blk_mode_t mode = 0;
 476
 477         if (file->f_mode & FMODE_READ)
 478                 mode |= BLK_OPEN_READ;
 479         if (file->f_mode & FMODE_WRITE)
 480                 mode |= BLK_OPEN_WRITE;
 481         if (file->private_data)
 482                 mode |= BLK_OPEN_EXCL;
 483         if (file->f_flags & O_NDELAY)
 484                 mode |= BLK_OPEN_NDELAY;
 485
 486         /*
 487          * If all bits in O_ACCMODE set (aka O_RDWR | O_WRONLY), the floppy
 488          * driver has historically allowed ioctls as if the file was opened for
 489          * writing, but does not allow and actual reads or writes.
 490          */
 491         if ((file->f_flags & O_ACCMODE) == (O_RDWR | O_WRONLY))
 492                 mode |= BLK_OPEN_WRITE_IOCTL;
 493
 494         return mode;
 495 }
 496
 497 static int blkdev_open(struct inode *inode, struct file *filp)
 498 {
 499         struct block_device *bdev;
 500
 501         /*
 502          * Preserve backwards compatibility and allow large file access
 503          * even if userspace doesn't ask for it explicitly. Some mkfs
 504          * binary needs it. We might want to drop this workaround
 505          * during an unstable branch.
 506          */
 507         filp->f_flags |= O_LARGEFILE;
 508         filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
 509
 510         /*
 511          * Use the file private data to store the holder for exclusive openes.
 512          * file_to_blk_mode relies on it being present to set BLK_OPEN_EXCL.
 513          */
 514         if (filp->f_flags & O_EXCL)
 515                 filp->private_data = filp;
 516
 517         bdev = blkdev_get_by_dev(inode->i_rdev, file_to_blk_mode(filp),
 518                                  filp->private_data, NULL);
 519         if (IS_ERR(bdev))
 520                 return PTR_ERR(bdev);
 521
 522         filp->f_mapping = bdev->bd_inode->i_mapping;
 523         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 524         return 0;
 525 }
 526
 527 static int blkdev_release(struct inode *inode, struct file *filp)
 528 {
 529         blkdev_put(I_BDEV(filp->f_mapping->host), filp->private_data);
 530         return 0;
 531 }
 532
 533 /*
 534  * Write data to the block device.  Only intended for the block device itself
 535  * and the raw driver which basically is a fake block device.
 536  *
 537  * Does not take i_mutex for the write and thus is not for general purpose
 538  * use.
 539  */
 540 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 541 {
 542         struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 543         struct inode *bd_inode = bdev->bd_inode;
 544         loff_t size = bdev_nr_bytes(bdev);
 545         size_t shorted = 0;
 546         ssize_t ret;
 547
 548         if (bdev_read_only(bdev))
 549                 return -EPERM;
 550
 551         if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
 552                 return -ETXTBSY;
 553
 554         if (!iov_iter_count(from))
 555                 return 0;
 556
 557         if (iocb->ki_pos >= size)
 558                 return -ENOSPC;
 559
 560         if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
 561                 return -EOPNOTSUPP;
 562
 563         size -= iocb->ki_pos;
 564         if (iov_iter_count(from) > size) {
 565                 shorted = iov_iter_count(from) - size;
 566                 iov_iter_truncate(from, size);
 567         }
 568
 569         ret = __generic_file_write_iter(iocb, from);
 570         if (ret > 0)
 571                 ret = generic_write_sync(iocb, ret);
 572         iov_iter_reexpand(from, iov_iter_count(from) + shorted);
 573         return ret;
 574 }
 575
 576 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 577 {
 578         struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 579         loff_t size = bdev_nr_bytes(bdev);
 580         loff_t pos = iocb->ki_pos;
 581         size_t shorted = 0;
 582         ssize_t ret = 0;
 583         size_t count;
 584
 585         if (unlikely(pos + iov_iter_count(to) > size)) {
 586                 if (pos >= size)
 587                         return 0;
 588                 size -= pos;
 589                 shorted = iov_iter_count(to) - size;
 590                 iov_iter_truncate(to, size);
 591         }
 592
 593         count = iov_iter_count(to);
 594         if (!count)
 595                 goto reexpand; /* skip atime */
 596
 597         if (iocb->ki_flags & IOCB_DIRECT) {
 598                 struct address_space *mapping = iocb->ki_filp->f_mapping;
 599
 600                 if (iocb->ki_flags & IOCB_NOWAIT) {
 601                         if (filemap_range_needs_writeback(mapping, pos,
 602                                                           pos + count - 1)) {
 603                                 ret = -EAGAIN;
 604                                 goto reexpand;
 605                         }
 606                 } else {
 607                         ret = filemap_write_and_wait_range(mapping, pos,
 608                                                            pos + count - 1);
 609                         if (ret < 0)
 610                                 goto reexpand;
 611                 }
 612
 613                 file_accessed(iocb->ki_filp);
 614
 615                 ret = blkdev_direct_IO(iocb, to);
 616                 if (ret >= 0) {
 617                         iocb->ki_pos += ret;
 618                         count -= ret;
 619                 }
 620                 iov_iter_revert(to, count - iov_iter_count(to));
 621                 if (ret < 0 || !count)
 622                         goto reexpand;
 623         }
 624
 625         ret = filemap_read(iocb, to, ret);
 626
 627 reexpand:
 628         if (unlikely(shorted))
 629                 iov_iter_reexpand(to, iov_iter_count(to) + shorted);
 630         return ret;
 631 }
 632
 633 #define BLKDEV_FALLOC_FL_SUPPORTED                                      \
 634                 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
 635                  FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
 636
 637 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 638                              loff_t len)
 639 {
 640         struct inode *inode = bdev_file_inode(file);
 641         struct block_device *bdev = I_BDEV(inode);
 642         loff_t end = start + len - 1;
 643         loff_t isize;
 644         int error;
 645
 646         /* Fail if we don't recognize the flags. */
 647         if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
 648                 return -EOPNOTSUPP;
 649
 650         /* Don't go off the end of the device. */
 651         isize = bdev_nr_bytes(bdev);
 652         if (start >= isize)
 653                 return -EINVAL;
 654         if (end >= isize) {
 655                 if (mode & FALLOC_FL_KEEP_SIZE) {
 656                         len = isize - start;
 657                         end = start + len - 1;
 658                 } else
 659                         return -EINVAL;
 660         }
 661
 662         /*
 663          * Don't allow IO that isn't aligned to logical block size.
 664          */
 665         if ((start | len) & (bdev_logical_block_size(bdev) - 1))
 666                 return -EINVAL;
 667
 668         filemap_invalidate_lock(inode->i_mapping);
 669
 670         /* Invalidate the page cache, including dirty pages. */
 671         error = truncate_bdev_range(bdev, file_to_blk_mode(file), start, end);
 672         if (error)
 673                 goto fail;
 674
 675         switch (mode) {
 676         case FALLOC_FL_ZERO_RANGE:
 677         case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
 678                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
 679                                              len >> SECTOR_SHIFT, GFP_KERNEL,
 680                                              BLKDEV_ZERO_NOUNMAP);
 681                 break;
 682         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
 683                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
 684                                              len >> SECTOR_SHIFT, GFP_KERNEL,
 685                                              BLKDEV_ZERO_NOFALLBACK);
 686                 break;
 687         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
 688                 error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
 689                                              len >> SECTOR_SHIFT, GFP_KERNEL);
 690                 break;
 691         default:
 692                 error = -EOPNOTSUPP;
 693         }
 694
 695  fail:
 696         filemap_invalidate_unlock(inode->i_mapping);
 697         return error;
 698 }
 699
 700 const struct file_operations def_blk_fops = {
 701         .open           = blkdev_open,
 702         .release        = blkdev_release,
 703         .llseek         = blkdev_llseek,
 704         .read_iter      = blkdev_read_iter,
 705         .write_iter     = blkdev_write_iter,
 706         .iopoll         = iocb_bio_iopoll,
 707         .mmap           = generic_file_mmap,
 708         .fsync          = blkdev_fsync,
 709         .unlocked_ioctl = blkdev_ioctl,
 710 #ifdef CONFIG_COMPAT
 711         .compat_ioctl   = compat_blkdev_ioctl,
 712 #endif
 713         .splice_read    = filemap_splice_read,
 714         .splice_write   = iter_file_splice_write,
 715         .fallocate      = blkdev_fallocate,
 716 };
 717
 718 static __init int blkdev_init(void)
 719 {
 720         return bioset_init(&blkdev_dio_pool, 4,
 721                                 offsetof(struct blkdev_dio, bio),
 722                                 BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
 723 }
 724 module_init(blkdev_init);