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/iomap.h>
  19 #include <linux/module.h>
  20 #include <linux/io_uring/cmd.h>
  21 #include "blk.h"
  22
  23 static inline struct inode *bdev_file_inode(struct file *file)
  24 {
  25         return file->f_mapping->host;
  26 }
  27
  28 static blk_opf_t dio_bio_write_op(struct kiocb *iocb)
  29 {
  30         blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
  31
  32         /* avoid the need for a I/O completion work item */
  33         if (iocb_is_dsync(iocb))
  34                 opf |= REQ_FUA;
  35         return opf;
  36 }
  37
  38 static bool blkdev_dio_invalid(struct block_device *bdev, loff_t pos,
  39                                 struct iov_iter *iter, bool is_atomic)
  40 {
  41         if (is_atomic && !generic_atomic_write_valid(iter, pos))
  42                 return true;
  43
  44         return pos & (bdev_logical_block_size(bdev) - 1) ||
  45                 !bdev_iter_is_aligned(bdev, iter);
  46 }
  47
  48 #define DIO_INLINE_BIO_VECS 4
  49
  50 static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
  51                 struct iov_iter *iter, struct block_device *bdev,
  52                 unsigned int nr_pages)
  53 {
  54         struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
  55         loff_t pos = iocb->ki_pos;
  56         bool should_dirty = false;
  57         struct bio bio;
  58         ssize_t ret;
  59
  60         if (nr_pages <= DIO_INLINE_BIO_VECS)
  61                 vecs = inline_vecs;
  62         else {
  63                 vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
  64                                      GFP_KERNEL);
  65                 if (!vecs)
  66                         return -ENOMEM;
  67         }
  68
  69         if (iov_iter_rw(iter) == READ) {
  70                 bio_init(&bio, bdev, vecs, nr_pages, REQ_OP_READ);
  71                 if (user_backed_iter(iter))
  72                         should_dirty = true;
  73         } else {
  74                 bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb));
  75         }
  76         bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT;
  77         bio.bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
  78         bio.bi_ioprio = iocb->ki_ioprio;
  79         if (iocb->ki_flags & IOCB_ATOMIC)
  80                 bio.bi_opf |= REQ_ATOMIC;
  81
  82         ret = bio_iov_iter_get_pages(&bio, iter);
  83         if (unlikely(ret))
  84                 goto out;
  85         ret = bio.bi_iter.bi_size;
  86
  87         if (iov_iter_rw(iter) == WRITE)
  88                 task_io_account_write(ret);
  89
  90         if (iocb->ki_flags & IOCB_NOWAIT)
  91                 bio.bi_opf |= REQ_NOWAIT;
  92
  93         submit_bio_wait(&bio);
  94
  95         bio_release_pages(&bio, should_dirty);
  96         if (unlikely(bio.bi_status))
  97                 ret = blk_status_to_errno(bio.bi_status);
  98
  99 out:
 100         if (vecs != inline_vecs)
 101                 kfree(vecs);
 102
 103         bio_uninit(&bio);
 104
 105         return ret;
 106 }
 107
 108 enum {
 109         DIO_SHOULD_DIRTY        = 1,
 110         DIO_IS_SYNC             = 2,
 111 };
 112
 113 struct blkdev_dio {
 114         union {
 115                 struct kiocb            *iocb;
 116                 struct task_struct      *waiter;
 117         };
 118         size_t                  size;
 119         atomic_t                ref;
 120         unsigned int            flags;
 121         struct bio              bio ____cacheline_aligned_in_smp;
 122 };
 123
 124 static struct bio_set blkdev_dio_pool;
 125
 126 static void blkdev_bio_end_io(struct bio *bio)
 127 {
 128         struct blkdev_dio *dio = bio->bi_private;
 129         bool should_dirty = dio->flags & DIO_SHOULD_DIRTY;
 130
 131         if (bio->bi_status && !dio->bio.bi_status)
 132                 dio->bio.bi_status = bio->bi_status;
 133
 134         if (atomic_dec_and_test(&dio->ref)) {
 135                 if (!(dio->flags & DIO_IS_SYNC)) {
 136                         struct kiocb *iocb = dio->iocb;
 137                         ssize_t ret;
 138
 139                         WRITE_ONCE(iocb->private, NULL);
 140
 141                         if (likely(!dio->bio.bi_status)) {
 142                                 ret = dio->size;
 143                                 iocb->ki_pos += ret;
 144                         } else {
 145                                 ret = blk_status_to_errno(dio->bio.bi_status);
 146                         }
 147
 148                         dio->iocb->ki_complete(iocb, ret);
 149                         bio_put(&dio->bio);
 150                 } else {
 151                         struct task_struct *waiter = dio->waiter;
 152
 153                         WRITE_ONCE(dio->waiter, NULL);
 154                         blk_wake_io_task(waiter);
 155                 }
 156         }
 157
 158         if (should_dirty) {
 159                 bio_check_pages_dirty(bio);
 160         } else {
 161                 bio_release_pages(bio, false);
 162                 bio_put(bio);
 163         }
 164 }
 165
 166 static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
 167                 struct block_device *bdev, unsigned int nr_pages)
 168 {
 169         struct blk_plug plug;
 170         struct blkdev_dio *dio;
 171         struct bio *bio;
 172         bool is_read = (iov_iter_rw(iter) == READ), is_sync;
 173         blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
 174         loff_t pos = iocb->ki_pos;
 175         int ret = 0;
 176
 177         if (iocb->ki_flags & IOCB_ALLOC_CACHE)
 178                 opf |= REQ_ALLOC_CACHE;
 179         bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
 180                                &blkdev_dio_pool);
 181         dio = container_of(bio, struct blkdev_dio, bio);
 182         atomic_set(&dio->ref, 1);
 183         /*
 184          * Grab an extra reference to ensure the dio structure which is embedded
 185          * into the first bio stays around.
 186          */
 187         bio_get(bio);
 188
 189         is_sync = is_sync_kiocb(iocb);
 190         if (is_sync) {
 191                 dio->flags = DIO_IS_SYNC;
 192                 dio->waiter = current;
 193         } else {
 194                 dio->flags = 0;
 195                 dio->iocb = iocb;
 196         }
 197
 198         dio->size = 0;
 199         if (is_read && user_backed_iter(iter))
 200                 dio->flags |= DIO_SHOULD_DIRTY;
 201
 202         blk_start_plug(&plug);
 203
 204         for (;;) {
 205                 bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
 206                 bio->bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
 207                 bio->bi_private = dio;
 208                 bio->bi_end_io = blkdev_bio_end_io;
 209                 bio->bi_ioprio = iocb->ki_ioprio;
 210
 211                 ret = bio_iov_iter_get_pages(bio, iter);
 212                 if (unlikely(ret)) {
 213                         bio->bi_status = BLK_STS_IOERR;
 214                         bio_endio(bio);
 215                         break;
 216                 }
 217                 if (iocb->ki_flags & IOCB_NOWAIT) {
 218                         /*
 219                          * This is nonblocking IO, and we need to allocate
 220                          * another bio if we have data left to map. As we
 221                          * cannot guarantee that one of the sub bios will not
 222                          * fail getting issued FOR NOWAIT and as error results
 223                          * are coalesced across all of them, be safe and ask for
 224                          * a retry of this from blocking context.
 225                          */
 226                         if (unlikely(iov_iter_count(iter))) {
 227                                 bio_release_pages(bio, false);
 228                                 bio_clear_flag(bio, BIO_REFFED);
 229                                 bio_put(bio);
 230                                 blk_finish_plug(&plug);
 231                                 return -EAGAIN;
 232                         }
 233                         bio->bi_opf |= REQ_NOWAIT;
 234                 }
 235
 236                 if (is_read) {
 237                         if (dio->flags & DIO_SHOULD_DIRTY)
 238                                 bio_set_pages_dirty(bio);
 239                 } else {
 240                         task_io_account_write(bio->bi_iter.bi_size);
 241                 }
 242                 dio->size += bio->bi_iter.bi_size;
 243                 pos += bio->bi_iter.bi_size;
 244
 245                 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
 246                 if (!nr_pages) {
 247                         submit_bio(bio);
 248                         break;
 249                 }
 250                 atomic_inc(&dio->ref);
 251                 submit_bio(bio);
 252                 bio = bio_alloc(bdev, nr_pages, opf, GFP_KERNEL);
 253         }
 254
 255         blk_finish_plug(&plug);
 256
 257         if (!is_sync)
 258                 return -EIOCBQUEUED;
 259
 260         for (;;) {
 261                 set_current_state(TASK_UNINTERRUPTIBLE);
 262                 if (!READ_ONCE(dio->waiter))
 263                         break;
 264                 blk_io_schedule();
 265         }
 266         __set_current_state(TASK_RUNNING);
 267
 268         if (!ret)
 269                 ret = blk_status_to_errno(dio->bio.bi_status);
 270         if (likely(!ret))
 271                 ret = dio->size;
 272
 273         bio_put(&dio->bio);
 274         return ret;
 275 }
 276
 277 static void blkdev_bio_end_io_async(struct bio *bio)
 278 {
 279         struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio);
 280         struct kiocb *iocb = dio->iocb;
 281         ssize_t ret;
 282
 283         WRITE_ONCE(iocb->private, NULL);
 284
 285         if (likely(!bio->bi_status)) {
 286                 ret = dio->size;
 287                 iocb->ki_pos += ret;
 288         } else {
 289                 ret = blk_status_to_errno(bio->bi_status);
 290         }
 291
 292         iocb->ki_complete(iocb, ret);
 293
 294         if (dio->flags & DIO_SHOULD_DIRTY) {
 295                 bio_check_pages_dirty(bio);
 296         } else {
 297                 bio_release_pages(bio, false);
 298                 bio_put(bio);
 299         }
 300 }
 301
 302 static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
 303                                         struct iov_iter *iter,
 304                                         struct block_device *bdev,
 305                                         unsigned int nr_pages)
 306 {
 307         bool is_read = iov_iter_rw(iter) == READ;
 308         blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
 309         struct blkdev_dio *dio;
 310         struct bio *bio;
 311         loff_t pos = iocb->ki_pos;
 312         int ret = 0;
 313
 314         if (iocb->ki_flags & IOCB_ALLOC_CACHE)
 315                 opf |= REQ_ALLOC_CACHE;
 316         bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
 317                                &blkdev_dio_pool);
 318         dio = container_of(bio, struct blkdev_dio, bio);
 319         dio->flags = 0;
 320         dio->iocb = iocb;
 321         bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
 322         bio->bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
 323         bio->bi_end_io = blkdev_bio_end_io_async;
 324         bio->bi_ioprio = iocb->ki_ioprio;
 325
 326         if (iov_iter_is_bvec(iter)) {
 327                 /*
 328                  * Users don't rely on the iterator being in any particular
 329                  * state for async I/O returning -EIOCBQUEUED, hence we can
 330                  * avoid expensive iov_iter_advance(). Bypass
 331                  * bio_iov_iter_get_pages() and set the bvec directly.
 332                  */
 333                 bio_iov_bvec_set(bio, iter);
 334         } else {
 335                 ret = bio_iov_iter_get_pages(bio, iter);
 336                 if (unlikely(ret)) {
 337                         bio_put(bio);
 338                         return ret;
 339                 }
 340         }
 341         dio->size = bio->bi_iter.bi_size;
 342
 343         if (is_read) {
 344                 if (user_backed_iter(iter)) {
 345                         dio->flags |= DIO_SHOULD_DIRTY;
 346                         bio_set_pages_dirty(bio);
 347                 }
 348         } else {
 349                 task_io_account_write(bio->bi_iter.bi_size);
 350         }
 351
 352         if (iocb->ki_flags & IOCB_ATOMIC)
 353                 bio->bi_opf |= REQ_ATOMIC;
 354
 355         if (iocb->ki_flags & IOCB_NOWAIT)
 356                 bio->bi_opf |= REQ_NOWAIT;
 357
 358         if (iocb->ki_flags & IOCB_HIPRI) {
 359                 bio->bi_opf |= REQ_POLLED;
 360                 submit_bio(bio);
 361                 WRITE_ONCE(iocb->private, bio);
 362         } else {
 363                 submit_bio(bio);
 364         }
 365         return -EIOCBQUEUED;
 366 }
 367
 368 static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 369 {
 370         struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 371         bool is_atomic = iocb->ki_flags & IOCB_ATOMIC;
 372         unsigned int nr_pages;
 373
 374         if (!iov_iter_count(iter))
 375                 return 0;
 376
 377         if (blkdev_dio_invalid(bdev, iocb->ki_pos, iter, is_atomic))
 378                 return -EINVAL;
 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, bdev,
 384                                                         nr_pages);
 385                 return __blkdev_direct_IO_async(iocb, iter, bdev, nr_pages);
 386         } else if (is_atomic) {
 387                 return -EINVAL;
 388         }
 389         return __blkdev_direct_IO(iocb, iter, bdev, bio_max_segs(nr_pages));
 390 }
 391
 392 static int blkdev_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 393                 unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
 394 {
 395         struct block_device *bdev = I_BDEV(inode);
 396         loff_t isize = i_size_read(inode);
 397
 398         if (offset >= isize)
 399                 return -EIO;
 400
 401         iomap->bdev = bdev;
 402         iomap->offset = ALIGN_DOWN(offset, bdev_logical_block_size(bdev));
 403         iomap->type = IOMAP_MAPPED;
 404         iomap->addr = iomap->offset;
 405         iomap->length = isize - iomap->offset;
 406         iomap->flags |= IOMAP_F_BUFFER_HEAD; /* noop for !CONFIG_BUFFER_HEAD */
 407         return 0;
 408 }
 409
 410 static const struct iomap_ops blkdev_iomap_ops = {
 411         .iomap_begin            = blkdev_iomap_begin,
 412 };
 413
 414 #ifdef CONFIG_BUFFER_HEAD
 415 static int blkdev_get_block(struct inode *inode, sector_t iblock,
 416                 struct buffer_head *bh, int create)
 417 {
 418         bh->b_bdev = I_BDEV(inode);
 419         bh->b_blocknr = iblock;
 420         set_buffer_mapped(bh);
 421         return 0;
 422 }
 423
 424 /*
 425  * We cannot call mpage_writepages() as it does not take the buffer lock.
 426  * We must use block_write_full_folio() directly which holds the buffer
 427  * lock.  The buffer lock provides the synchronisation with writeback
 428  * that filesystems rely on when they use the blockdev's mapping.
 429  */
 430 static int blkdev_writepages(struct address_space *mapping,
 431                 struct writeback_control *wbc)
 432 {
 433         struct blk_plug plug;
 434         int err;
 435
 436         blk_start_plug(&plug);
 437         err = write_cache_pages(mapping, wbc, block_write_full_folio,
 438                         blkdev_get_block);
 439         blk_finish_plug(&plug);
 440
 441         return err;
 442 }
 443
 444 static int blkdev_read_folio(struct file *file, struct folio *folio)
 445 {
 446         return block_read_full_folio(folio, blkdev_get_block);
 447 }
 448
 449 static void blkdev_readahead(struct readahead_control *rac)
 450 {
 451         mpage_readahead(rac, blkdev_get_block);
 452 }
 453
 454 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
 455                 loff_t pos, unsigned len, struct folio **foliop, void **fsdata)
 456 {
 457         return block_write_begin(mapping, pos, len, foliop, blkdev_get_block);
 458 }
 459
 460 static int blkdev_write_end(struct file *file, struct address_space *mapping,
 461                 loff_t pos, unsigned len, unsigned copied, struct folio *folio,
 462                 void *fsdata)
 463 {
 464         int ret;
 465         ret = block_write_end(file, mapping, pos, len, copied, folio, fsdata);
 466
 467         folio_unlock(folio);
 468         folio_put(folio);
 469
 470         return ret;
 471 }
 472
 473 const struct address_space_operations def_blk_aops = {
 474         .dirty_folio    = block_dirty_folio,
 475         .invalidate_folio = block_invalidate_folio,
 476         .read_folio     = blkdev_read_folio,
 477         .readahead      = blkdev_readahead,
 478         .writepages     = blkdev_writepages,
 479         .write_begin    = blkdev_write_begin,
 480         .write_end      = blkdev_write_end,
 481         .migrate_folio  = buffer_migrate_folio_norefs,
 482         .is_dirty_writeback = buffer_check_dirty_writeback,
 483 };
 484 #else /* CONFIG_BUFFER_HEAD */
 485 static int blkdev_read_folio(struct file *file, struct folio *folio)
 486 {
 487         return iomap_read_folio(folio, &blkdev_iomap_ops);
 488 }
 489
 490 static void blkdev_readahead(struct readahead_control *rac)
 491 {
 492         iomap_readahead(rac, &blkdev_iomap_ops);
 493 }
 494
 495 static int blkdev_map_blocks(struct iomap_writepage_ctx *wpc,
 496                 struct inode *inode, loff_t offset, unsigned int len)
 497 {
 498         loff_t isize = i_size_read(inode);
 499
 500         if (WARN_ON_ONCE(offset >= isize))
 501                 return -EIO;
 502         if (offset >= wpc->iomap.offset &&
 503             offset < wpc->iomap.offset + wpc->iomap.length)
 504                 return 0;
 505         return blkdev_iomap_begin(inode, offset, isize - offset,
 506                                   IOMAP_WRITE, &wpc->iomap, NULL);
 507 }
 508
 509 static const struct iomap_writeback_ops blkdev_writeback_ops = {
 510         .map_blocks             = blkdev_map_blocks,
 511 };
 512
 513 static int blkdev_writepages(struct address_space *mapping,
 514                 struct writeback_control *wbc)
 515 {
 516         struct iomap_writepage_ctx wpc = { };
 517
 518         return iomap_writepages(mapping, wbc, &wpc, &blkdev_writeback_ops);
 519 }
 520
 521 const struct address_space_operations def_blk_aops = {
 522         .dirty_folio    = filemap_dirty_folio,
 523         .release_folio          = iomap_release_folio,
 524         .invalidate_folio       = iomap_invalidate_folio,
 525         .read_folio             = blkdev_read_folio,
 526         .readahead              = blkdev_readahead,
 527         .writepages             = blkdev_writepages,
 528         .is_partially_uptodate  = iomap_is_partially_uptodate,
 529         .error_remove_folio     = generic_error_remove_folio,
 530         .migrate_folio          = filemap_migrate_folio,
 531 };
 532 #endif /* CONFIG_BUFFER_HEAD */
 533
 534 /*
 535  * for a block special file file_inode(file)->i_size is zero
 536  * so we compute the size by hand (just as in block_read/write above)
 537  */
 538 static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
 539 {
 540         struct inode *bd_inode = bdev_file_inode(file);
 541         loff_t retval;
 542
 543         inode_lock(bd_inode);
 544         retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
 545         inode_unlock(bd_inode);
 546         return retval;
 547 }
 548
 549 static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
 550                 int datasync)
 551 {
 552         struct block_device *bdev = I_BDEV(filp->f_mapping->host);
 553         int error;
 554
 555         error = file_write_and_wait_range(filp, start, end);
 556         if (error)
 557                 return error;
 558
 559         /*
 560          * There is no need to serialise calls to blkdev_issue_flush with
 561          * i_mutex and doing so causes performance issues with concurrent
 562          * O_SYNC writers to a block device.
 563          */
 564         error = blkdev_issue_flush(bdev);
 565         if (error == -EOPNOTSUPP)
 566                 error = 0;
 567
 568         return error;
 569 }
 570
 571 /**
 572  * file_to_blk_mode - get block open flags from file flags
 573  * @file: file whose open flags should be converted
 574  *
 575  * Look at file open flags and generate corresponding block open flags from
 576  * them. The function works both for file just being open (e.g. during ->open
 577  * callback) and for file that is already open. This is actually non-trivial
 578  * (see comment in the function).
 579  */
 580 blk_mode_t file_to_blk_mode(struct file *file)
 581 {
 582         blk_mode_t mode = 0;
 583
 584         if (file->f_mode & FMODE_READ)
 585                 mode |= BLK_OPEN_READ;
 586         if (file->f_mode & FMODE_WRITE)
 587                 mode |= BLK_OPEN_WRITE;
 588         /*
 589          * do_dentry_open() clears O_EXCL from f_flags, use file->private_data
 590          * to determine whether the open was exclusive for already open files.
 591          */
 592         if (file->private_data)
 593                 mode |= BLK_OPEN_EXCL;
 594         else if (file->f_flags & O_EXCL)
 595                 mode |= BLK_OPEN_EXCL;
 596         if (file->f_flags & O_NDELAY)
 597                 mode |= BLK_OPEN_NDELAY;
 598
 599         /*
 600          * If all bits in O_ACCMODE set (aka O_RDWR | O_WRONLY), the floppy
 601          * driver has historically allowed ioctls as if the file was opened for
 602          * writing, but does not allow and actual reads or writes.
 603          */
 604         if ((file->f_flags & O_ACCMODE) == (O_RDWR | O_WRONLY))
 605                 mode |= BLK_OPEN_WRITE_IOCTL;
 606
 607         return mode;
 608 }
 609
 610 static int blkdev_open(struct inode *inode, struct file *filp)
 611 {
 612         struct block_device *bdev;
 613         blk_mode_t mode;
 614         int ret;
 615
 616         mode = file_to_blk_mode(filp);
 617         /* Use the file as the holder. */
 618         if (mode & BLK_OPEN_EXCL)
 619                 filp->private_data = filp;
 620         ret = bdev_permission(inode->i_rdev, mode, filp->private_data);
 621         if (ret)
 622                 return ret;
 623
 624         bdev = blkdev_get_no_open(inode->i_rdev);
 625         if (!bdev)
 626                 return -ENXIO;
 627
 628         if (bdev_can_atomic_write(bdev) && filp->f_flags & O_DIRECT)
 629                 filp->f_mode |= FMODE_CAN_ATOMIC_WRITE;
 630
 631         ret = bdev_open(bdev, mode, filp->private_data, NULL, filp);
 632         if (ret)
 633                 blkdev_put_no_open(bdev);
 634         return ret;
 635 }
 636
 637 static int blkdev_release(struct inode *inode, struct file *filp)
 638 {
 639         bdev_release(filp);
 640         return 0;
 641 }
 642
 643 static ssize_t
 644 blkdev_direct_write(struct kiocb *iocb, struct iov_iter *from)
 645 {
 646         size_t count = iov_iter_count(from);
 647         ssize_t written;
 648
 649         written = kiocb_invalidate_pages(iocb, count);
 650         if (written) {
 651                 if (written == -EBUSY)
 652                         return 0;
 653                 return written;
 654         }
 655
 656         written = blkdev_direct_IO(iocb, from);
 657         if (written > 0) {
 658                 kiocb_invalidate_post_direct_write(iocb, count);
 659                 iocb->ki_pos += written;
 660                 count -= written;
 661         }
 662         if (written != -EIOCBQUEUED)
 663                 iov_iter_revert(from, count - iov_iter_count(from));
 664         return written;
 665 }
 666
 667 static ssize_t blkdev_buffered_write(struct kiocb *iocb, struct iov_iter *from)
 668 {
 669         return iomap_file_buffered_write(iocb, from, &blkdev_iomap_ops, NULL);
 670 }
 671
 672 /*
 673  * Write data to the block device.  Only intended for the block device itself
 674  * and the raw driver which basically is a fake block device.
 675  *
 676  * Does not take i_mutex for the write and thus is not for general purpose
 677  * use.
 678  */
 679 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 680 {
 681         struct file *file = iocb->ki_filp;
 682         struct inode *bd_inode = bdev_file_inode(file);
 683         struct block_device *bdev = I_BDEV(bd_inode);
 684         loff_t size = bdev_nr_bytes(bdev);
 685         size_t shorted = 0;
 686         ssize_t ret;
 687
 688         if (bdev_read_only(bdev))
 689                 return -EPERM;
 690
 691         if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
 692                 return -ETXTBSY;
 693
 694         if (!iov_iter_count(from))
 695                 return 0;
 696
 697         if (iocb->ki_pos >= size)
 698                 return -ENOSPC;
 699
 700         if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
 701                 return -EOPNOTSUPP;
 702
 703         size -= iocb->ki_pos;
 704         if (iov_iter_count(from) > size) {
 705                 shorted = iov_iter_count(from) - size;
 706                 iov_iter_truncate(from, size);
 707         }
 708
 709         ret = file_update_time(file);
 710         if (ret)
 711                 return ret;
 712
 713         if (iocb->ki_flags & IOCB_DIRECT) {
 714                 ret = blkdev_direct_write(iocb, from);
 715                 if (ret >= 0 && iov_iter_count(from))
 716                         ret = direct_write_fallback(iocb, from, ret,
 717                                         blkdev_buffered_write(iocb, from));
 718         } else {
 719                 ret = blkdev_buffered_write(iocb, from);
 720         }
 721
 722         if (ret > 0)
 723                 ret = generic_write_sync(iocb, ret);
 724         iov_iter_reexpand(from, iov_iter_count(from) + shorted);
 725         return ret;
 726 }
 727
 728 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 729 {
 730         struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 731         loff_t size = bdev_nr_bytes(bdev);
 732         loff_t pos = iocb->ki_pos;
 733         size_t shorted = 0;
 734         ssize_t ret = 0;
 735         size_t count;
 736
 737         if (unlikely(pos + iov_iter_count(to) > size)) {
 738                 if (pos >= size)
 739                         return 0;
 740                 size -= pos;
 741                 shorted = iov_iter_count(to) - size;
 742                 iov_iter_truncate(to, size);
 743         }
 744
 745         count = iov_iter_count(to);
 746         if (!count)
 747                 goto reexpand; /* skip atime */
 748
 749         if (iocb->ki_flags & IOCB_DIRECT) {
 750                 ret = kiocb_write_and_wait(iocb, count);
 751                 if (ret < 0)
 752                         goto reexpand;
 753                 file_accessed(iocb->ki_filp);
 754
 755                 ret = blkdev_direct_IO(iocb, to);
 756                 if (ret >= 0) {
 757                         iocb->ki_pos += ret;
 758                         count -= ret;
 759                 }
 760                 iov_iter_revert(to, count - iov_iter_count(to));
 761                 if (ret < 0 || !count)
 762                         goto reexpand;
 763         }
 764
 765         ret = filemap_read(iocb, to, ret);
 766
 767 reexpand:
 768         if (unlikely(shorted))
 769                 iov_iter_reexpand(to, iov_iter_count(to) + shorted);
 770         return ret;
 771 }
 772
 773 #define BLKDEV_FALLOC_FL_SUPPORTED                                      \
 774                 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
 775                  FALLOC_FL_ZERO_RANGE)
 776
 777 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 778                              loff_t len)
 779 {
 780         struct inode *inode = bdev_file_inode(file);
 781         struct block_device *bdev = I_BDEV(inode);
 782         loff_t end = start + len - 1;
 783         loff_t isize;
 784         int error;
 785
 786         /* Fail if we don't recognize the flags. */
 787         if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
 788                 return -EOPNOTSUPP;
 789
 790         /* Don't go off the end of the device. */
 791         isize = bdev_nr_bytes(bdev);
 792         if (start >= isize)
 793                 return -EINVAL;
 794         if (end >= isize) {
 795                 if (mode & FALLOC_FL_KEEP_SIZE) {
 796                         len = isize - start;
 797                         end = start + len - 1;
 798                 } else
 799                         return -EINVAL;
 800         }
 801
 802         /*
 803          * Don't allow IO that isn't aligned to logical block size.
 804          */
 805         if ((start | len) & (bdev_logical_block_size(bdev) - 1))
 806                 return -EINVAL;
 807
 808         filemap_invalidate_lock(inode->i_mapping);
 809
 810         /*
 811          * Invalidate the page cache, including dirty pages, for valid
 812          * de-allocate mode calls to fallocate().
 813          */
 814         switch (mode) {
 815         case FALLOC_FL_ZERO_RANGE:
 816         case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
 817                 error = truncate_bdev_range(bdev, file_to_blk_mode(file), start, end);
 818                 if (error)
 819                         goto fail;
 820
 821                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
 822                                              len >> SECTOR_SHIFT, GFP_KERNEL,
 823                                              BLKDEV_ZERO_NOUNMAP);
 824                 break;
 825         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
 826                 error = truncate_bdev_range(bdev, file_to_blk_mode(file), start, end);
 827                 if (error)
 828                         goto fail;
 829
 830                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
 831                                              len >> SECTOR_SHIFT, GFP_KERNEL,
 832                                              BLKDEV_ZERO_NOFALLBACK);
 833                 break;
 834         default:
 835                 error = -EOPNOTSUPP;
 836         }
 837
 838  fail:
 839         filemap_invalidate_unlock(inode->i_mapping);
 840         return error;
 841 }
 842
 843 static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
 844 {
 845         struct inode *bd_inode = bdev_file_inode(file);
 846
 847         if (bdev_read_only(I_BDEV(bd_inode)))
 848                 return generic_file_readonly_mmap(file, vma);
 849
 850         return generic_file_mmap(file, vma);
 851 }
 852
 853 const struct file_operations def_blk_fops = {
 854         .open           = blkdev_open,
 855         .release        = blkdev_release,
 856         .llseek         = blkdev_llseek,
 857         .read_iter      = blkdev_read_iter,
 858         .write_iter     = blkdev_write_iter,
 859         .iopoll         = iocb_bio_iopoll,
 860         .mmap           = blkdev_mmap,
 861         .fsync          = blkdev_fsync,
 862         .unlocked_ioctl = blkdev_ioctl,
 863 #ifdef CONFIG_COMPAT
 864         .compat_ioctl   = compat_blkdev_ioctl,
 865 #endif
 866         .splice_read    = filemap_splice_read,
 867         .splice_write   = iter_file_splice_write,
 868         .fallocate      = blkdev_fallocate,
 869         .uring_cmd      = blkdev_uring_cmd,
 870         .fop_flags      = FOP_BUFFER_RASYNC,
 871 };
 872
 873 static __init int blkdev_init(void)
 874 {
 875         return bioset_init(&blkdev_dio_pool, 4,
 876                                 offsetof(struct blkdev_dio, bio),
 877                                 BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
 878 }
 879 module_init(blkdev_init);