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 "blk.h"
  18
  19 static struct inode *bdev_file_inode(struct file *file)
  20 {
  21         return file->f_mapping->host;
  22 }
  23
  24 static int blkdev_get_block(struct inode *inode, sector_t iblock,
  25                 struct buffer_head *bh, int create)
  26 {
  27         bh->b_bdev = I_BDEV(inode);
  28         bh->b_blocknr = iblock;
  29         set_buffer_mapped(bh);
  30         return 0;
  31 }
  32
  33 static unsigned int dio_bio_write_op(struct kiocb *iocb)
  34 {
  35         unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
  36
  37         /* avoid the need for a I/O completion work item */
  38         if (iocb->ki_flags & IOCB_DSYNC)
  39                 op |= REQ_FUA;
  40         return op;
  41 }
  42
  43 #define DIO_INLINE_BIO_VECS 4
  44
  45 static void blkdev_bio_end_io_simple(struct bio *bio)
  46 {
  47         struct task_struct *waiter = bio->bi_private;
  48
  49         WRITE_ONCE(bio->bi_private, NULL);
  50         blk_wake_io_task(waiter);
  51 }
  52
  53 static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
  54                 struct iov_iter *iter, unsigned int nr_pages)
  55 {
  56         struct file *file = iocb->ki_filp;
  57         struct block_device *bdev = I_BDEV(bdev_file_inode(file));
  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         blk_qc_t qc;
  64
  65         if ((pos | iov_iter_alignment(iter)) &
  66             (bdev_logical_block_size(bdev) - 1))
  67                 return -EINVAL;
  68
  69         if (nr_pages <= DIO_INLINE_BIO_VECS)
  70                 vecs = inline_vecs;
  71         else {
  72                 vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
  73                                      GFP_KERNEL);
  74                 if (!vecs)
  75                         return -ENOMEM;
  76         }
  77
  78         bio_init(&bio, vecs, nr_pages);
  79         bio_set_dev(&bio, bdev);
  80         bio.bi_iter.bi_sector = pos >> 9;
  81         bio.bi_write_hint = iocb->ki_hint;
  82         bio.bi_private = current;
  83         bio.bi_end_io = blkdev_bio_end_io_simple;
  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) == READ) {
  92                 bio.bi_opf = REQ_OP_READ;
  93                 if (iter_is_iovec(iter))
  94                         should_dirty = true;
  95         } else {
  96                 bio.bi_opf = dio_bio_write_op(iocb);
  97                 task_io_account_write(ret);
  98         }
  99         if (iocb->ki_flags & IOCB_NOWAIT)
 100                 bio.bi_opf |= REQ_NOWAIT;
 101         if (iocb->ki_flags & IOCB_HIPRI)
 102                 bio_set_polled(&bio, iocb);
 103
 104         qc = submit_bio(&bio);
 105         for (;;) {
 106                 set_current_state(TASK_UNINTERRUPTIBLE);
 107                 if (!READ_ONCE(bio.bi_private))
 108                         break;
 109                 if (!(iocb->ki_flags & IOCB_HIPRI) ||
 110                     !blk_poll(bdev_get_queue(bdev), qc, true))
 111                         blk_io_schedule();
 112         }
 113         __set_current_state(TASK_RUNNING);
 114
 115         bio_release_pages(&bio, should_dirty);
 116         if (unlikely(bio.bi_status))
 117                 ret = blk_status_to_errno(bio.bi_status);
 118
 119 out:
 120         if (vecs != inline_vecs)
 121                 kfree(vecs);
 122
 123         bio_uninit(&bio);
 124
 125         return ret;
 126 }
 127
 128 struct blkdev_dio {
 129         union {
 130                 struct kiocb            *iocb;
 131                 struct task_struct      *waiter;
 132         };
 133         size_t                  size;
 134         atomic_t                ref;
 135         bool                    multi_bio : 1;
 136         bool                    should_dirty : 1;
 137         bool                    is_sync : 1;
 138         struct bio              bio;
 139 };
 140
 141 static struct bio_set blkdev_dio_pool;
 142
 143 static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
 144 {
 145         struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
 146         struct request_queue *q = bdev_get_queue(bdev);
 147
 148         return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
 149 }
 150
 151 static void blkdev_bio_end_io(struct bio *bio)
 152 {
 153         struct blkdev_dio *dio = bio->bi_private;
 154         bool should_dirty = dio->should_dirty;
 155
 156         if (bio->bi_status && !dio->bio.bi_status)
 157                 dio->bio.bi_status = bio->bi_status;
 158
 159         if (!dio->multi_bio || atomic_dec_and_test(&dio->ref)) {
 160                 if (!dio->is_sync) {
 161                         struct kiocb *iocb = dio->iocb;
 162                         ssize_t ret;
 163
 164                         if (likely(!dio->bio.bi_status)) {
 165                                 ret = dio->size;
 166                                 iocb->ki_pos += ret;
 167                         } else {
 168                                 ret = blk_status_to_errno(dio->bio.bi_status);
 169                         }
 170
 171                         dio->iocb->ki_complete(iocb, ret, 0);
 172                         if (dio->multi_bio)
 173                                 bio_put(&dio->bio);
 174                 } else {
 175                         struct task_struct *waiter = dio->waiter;
 176
 177                         WRITE_ONCE(dio->waiter, NULL);
 178                         blk_wake_io_task(waiter);
 179                 }
 180         }
 181
 182         if (should_dirty) {
 183                 bio_check_pages_dirty(bio);
 184         } else {
 185                 bio_release_pages(bio, false);
 186                 bio_put(bio);
 187         }
 188 }
 189
 190 static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
 191                 unsigned int nr_pages)
 192 {
 193         struct file *file = iocb->ki_filp;
 194         struct inode *inode = bdev_file_inode(file);
 195         struct block_device *bdev = I_BDEV(inode);
 196         struct blk_plug plug;
 197         struct blkdev_dio *dio;
 198         struct bio *bio;
 199         bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0;
 200         bool is_read = (iov_iter_rw(iter) == READ), is_sync;
 201         loff_t pos = iocb->ki_pos;
 202         blk_qc_t qc = BLK_QC_T_NONE;
 203         int ret = 0;
 204
 205         if ((pos | iov_iter_alignment(iter)) &
 206             (bdev_logical_block_size(bdev) - 1))
 207                 return -EINVAL;
 208
 209         bio = bio_alloc_kiocb(iocb, nr_pages, &blkdev_dio_pool);
 210
 211         dio = container_of(bio, struct blkdev_dio, bio);
 212         dio->is_sync = is_sync = is_sync_kiocb(iocb);
 213         if (dio->is_sync) {
 214                 dio->waiter = current;
 215                 bio_get(bio);
 216         } else {
 217                 dio->iocb = iocb;
 218         }
 219
 220         dio->size = 0;
 221         dio->multi_bio = false;
 222         dio->should_dirty = is_read && iter_is_iovec(iter);
 223
 224         /*
 225          * Don't plug for HIPRI/polled IO, as those should go straight
 226          * to issue
 227          */
 228         if (!is_poll)
 229                 blk_start_plug(&plug);
 230
 231         for (;;) {
 232                 bio_set_dev(bio, bdev);
 233                 bio->bi_iter.bi_sector = pos >> 9;
 234                 bio->bi_write_hint = iocb->ki_hint;
 235                 bio->bi_private = dio;
 236                 bio->bi_end_io = blkdev_bio_end_io;
 237                 bio->bi_ioprio = iocb->ki_ioprio;
 238
 239                 ret = bio_iov_iter_get_pages(bio, iter);
 240                 if (unlikely(ret)) {
 241                         bio->bi_status = BLK_STS_IOERR;
 242                         bio_endio(bio);
 243                         break;
 244                 }
 245
 246                 if (is_read) {
 247                         bio->bi_opf = REQ_OP_READ;
 248                         if (dio->should_dirty)
 249                                 bio_set_pages_dirty(bio);
 250                 } else {
 251                         bio->bi_opf = dio_bio_write_op(iocb);
 252                         task_io_account_write(bio->bi_iter.bi_size);
 253                 }
 254                 if (iocb->ki_flags & IOCB_NOWAIT)
 255                         bio->bi_opf |= REQ_NOWAIT;
 256
 257                 dio->size += bio->bi_iter.bi_size;
 258                 pos += bio->bi_iter.bi_size;
 259
 260                 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
 261                 if (!nr_pages) {
 262                         bool polled = false;
 263
 264                         if (iocb->ki_flags & IOCB_HIPRI) {
 265                                 bio_set_polled(bio, iocb);
 266                                 polled = true;
 267                         }
 268
 269                         qc = submit_bio(bio);
 270
 271                         if (polled)
 272                                 WRITE_ONCE(iocb->ki_cookie, qc);
 273                         break;
 274                 }
 275
 276                 if (!dio->multi_bio) {
 277                         /*
 278                          * AIO needs an extra reference to ensure the dio
 279                          * structure which is embedded into the first bio
 280                          * stays around.
 281                          */
 282                         if (!is_sync)
 283                                 bio_get(bio);
 284                         dio->multi_bio = true;
 285                         atomic_set(&dio->ref, 2);
 286                 } else {
 287                         atomic_inc(&dio->ref);
 288                 }
 289
 290                 submit_bio(bio);
 291                 bio = bio_alloc(GFP_KERNEL, nr_pages);
 292         }
 293
 294         if (!is_poll)
 295                 blk_finish_plug(&plug);
 296
 297         if (!is_sync)
 298                 return -EIOCBQUEUED;
 299
 300         for (;;) {
 301                 set_current_state(TASK_UNINTERRUPTIBLE);
 302                 if (!READ_ONCE(dio->waiter))
 303                         break;
 304
 305                 if (!(iocb->ki_flags & IOCB_HIPRI) ||
 306                     !blk_poll(bdev_get_queue(bdev), qc, true))
 307                         blk_io_schedule();
 308         }
 309         __set_current_state(TASK_RUNNING);
 310
 311         if (!ret)
 312                 ret = blk_status_to_errno(dio->bio.bi_status);
 313         if (likely(!ret))
 314                 ret = dio->size;
 315
 316         bio_put(&dio->bio);
 317         return ret;
 318 }
 319
 320 static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 321 {
 322         unsigned int nr_pages;
 323
 324         if (!iov_iter_count(iter))
 325                 return 0;
 326
 327         nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
 328         if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_VECS)
 329                 return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
 330
 331         return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
 332 }
 333
 334 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
 335 {
 336         return block_write_full_page(page, blkdev_get_block, wbc);
 337 }
 338
 339 static int blkdev_readpage(struct file * file, struct page * page)
 340 {
 341         return block_read_full_page(page, blkdev_get_block);
 342 }
 343
 344 static void blkdev_readahead(struct readahead_control *rac)
 345 {
 346         mpage_readahead(rac, blkdev_get_block);
 347 }
 348
 349 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
 350                 loff_t pos, unsigned len, unsigned flags, struct page **pagep,
 351                 void **fsdata)
 352 {
 353         return block_write_begin(mapping, pos, len, flags, pagep,
 354                                  blkdev_get_block);
 355 }
 356
 357 static int blkdev_write_end(struct file *file, struct address_space *mapping,
 358                 loff_t pos, unsigned len, unsigned copied, struct page *page,
 359                 void *fsdata)
 360 {
 361         int ret;
 362         ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
 363
 364         unlock_page(page);
 365         put_page(page);
 366
 367         return ret;
 368 }
 369
 370 static int blkdev_writepages(struct address_space *mapping,
 371                              struct writeback_control *wbc)
 372 {
 373         return generic_writepages(mapping, wbc);
 374 }
 375
 376 const struct address_space_operations def_blk_aops = {
 377         .set_page_dirty = __set_page_dirty_buffers,
 378         .readpage       = blkdev_readpage,
 379         .readahead      = blkdev_readahead,
 380         .writepage      = blkdev_writepage,
 381         .write_begin    = blkdev_write_begin,
 382         .write_end      = blkdev_write_end,
 383         .writepages     = blkdev_writepages,
 384         .direct_IO      = blkdev_direct_IO,
 385         .migratepage    = buffer_migrate_page_norefs,
 386         .is_dirty_writeback = buffer_check_dirty_writeback,
 387 };
 388
 389 /*
 390  * for a block special file file_inode(file)->i_size is zero
 391  * so we compute the size by hand (just as in block_read/write above)
 392  */
 393 static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
 394 {
 395         struct inode *bd_inode = bdev_file_inode(file);
 396         loff_t retval;
 397
 398         inode_lock(bd_inode);
 399         retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
 400         inode_unlock(bd_inode);
 401         return retval;
 402 }
 403
 404 static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
 405                 int datasync)
 406 {
 407         struct inode *bd_inode = bdev_file_inode(filp);
 408         struct block_device *bdev = I_BDEV(bd_inode);
 409         int error;
 410
 411         error = file_write_and_wait_range(filp, start, end);
 412         if (error)
 413                 return error;
 414
 415         /*
 416          * There is no need to serialise calls to blkdev_issue_flush with
 417          * i_mutex and doing so causes performance issues with concurrent
 418          * O_SYNC writers to a block device.
 419          */
 420         error = blkdev_issue_flush(bdev);
 421         if (error == -EOPNOTSUPP)
 422                 error = 0;
 423
 424         return error;
 425 }
 426
 427 static int blkdev_open(struct inode *inode, struct file *filp)
 428 {
 429         struct block_device *bdev;
 430
 431         /*
 432          * Preserve backwards compatibility and allow large file access
 433          * even if userspace doesn't ask for it explicitly. Some mkfs
 434          * binary needs it. We might want to drop this workaround
 435          * during an unstable branch.
 436          */
 437         filp->f_flags |= O_LARGEFILE;
 438         filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
 439
 440         if (filp->f_flags & O_NDELAY)
 441                 filp->f_mode |= FMODE_NDELAY;
 442         if (filp->f_flags & O_EXCL)
 443                 filp->f_mode |= FMODE_EXCL;
 444         if ((filp->f_flags & O_ACCMODE) == 3)
 445                 filp->f_mode |= FMODE_WRITE_IOCTL;
 446
 447         bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp);
 448         if (IS_ERR(bdev))
 449                 return PTR_ERR(bdev);
 450         filp->f_mapping = bdev->bd_inode->i_mapping;
 451         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 452         return 0;
 453 }
 454
 455 static int blkdev_close(struct inode *inode, struct file *filp)
 456 {
 457         struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
 458
 459         blkdev_put(bdev, filp->f_mode);
 460         return 0;
 461 }
 462
 463 static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 464 {
 465         struct block_device *bdev = I_BDEV(bdev_file_inode(file));
 466         fmode_t mode = file->f_mode;
 467
 468         /*
 469          * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
 470          * to updated it before every ioctl.
 471          */
 472         if (file->f_flags & O_NDELAY)
 473                 mode |= FMODE_NDELAY;
 474         else
 475                 mode &= ~FMODE_NDELAY;
 476
 477         return blkdev_ioctl(bdev, mode, cmd, arg);
 478 }
 479
 480 /*
 481  * Write data to the block device.  Only intended for the block device itself
 482  * and the raw driver which basically is a fake block device.
 483  *
 484  * Does not take i_mutex for the write and thus is not for general purpose
 485  * use.
 486  */
 487 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 488 {
 489         struct file *file = iocb->ki_filp;
 490         struct inode *bd_inode = bdev_file_inode(file);
 491         loff_t size = i_size_read(bd_inode);
 492         struct blk_plug plug;
 493         size_t shorted = 0;
 494         ssize_t ret;
 495
 496         if (bdev_read_only(I_BDEV(bd_inode)))
 497                 return -EPERM;
 498
 499         if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
 500                 return -ETXTBSY;
 501
 502         if (!iov_iter_count(from))
 503                 return 0;
 504
 505         if (iocb->ki_pos >= size)
 506                 return -ENOSPC;
 507
 508         if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
 509                 return -EOPNOTSUPP;
 510
 511         size -= iocb->ki_pos;
 512         if (iov_iter_count(from) > size) {
 513                 shorted = iov_iter_count(from) - size;
 514                 iov_iter_truncate(from, size);
 515         }
 516
 517         blk_start_plug(&plug);
 518         ret = __generic_file_write_iter(iocb, from);
 519         if (ret > 0)
 520                 ret = generic_write_sync(iocb, ret);
 521         iov_iter_reexpand(from, iov_iter_count(from) + shorted);
 522         blk_finish_plug(&plug);
 523         return ret;
 524 }
 525
 526 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 527 {
 528         struct file *file = iocb->ki_filp;
 529         struct inode *bd_inode = bdev_file_inode(file);
 530         loff_t size = i_size_read(bd_inode);
 531         loff_t pos = iocb->ki_pos;
 532         size_t shorted = 0;
 533         ssize_t ret;
 534
 535         if (pos >= size)
 536                 return 0;
 537
 538         size -= pos;
 539         if (iov_iter_count(to) > size) {
 540                 shorted = iov_iter_count(to) - size;
 541                 iov_iter_truncate(to, size);
 542         }
 543
 544         ret = generic_file_read_iter(iocb, to);
 545         iov_iter_reexpand(to, iov_iter_count(to) + shorted);
 546         return ret;
 547 }
 548
 549 #define BLKDEV_FALLOC_FL_SUPPORTED                                      \
 550                 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
 551                  FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
 552
 553 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 554                              loff_t len)
 555 {
 556         struct block_device *bdev = I_BDEV(bdev_file_inode(file));
 557         loff_t end = start + len - 1;
 558         loff_t isize;
 559         int error;
 560
 561         /* Fail if we don't recognize the flags. */
 562         if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
 563                 return -EOPNOTSUPP;
 564
 565         /* Don't go off the end of the device. */
 566         isize = i_size_read(bdev->bd_inode);
 567         if (start >= isize)
 568                 return -EINVAL;
 569         if (end >= isize) {
 570                 if (mode & FALLOC_FL_KEEP_SIZE) {
 571                         len = isize - start;
 572                         end = start + len - 1;
 573                 } else
 574                         return -EINVAL;
 575         }
 576
 577         /*
 578          * Don't allow IO that isn't aligned to logical block size.
 579          */
 580         if ((start | len) & (bdev_logical_block_size(bdev) - 1))
 581                 return -EINVAL;
 582
 583         /* Invalidate the page cache, including dirty pages. */
 584         error = truncate_bdev_range(bdev, file->f_mode, start, end);
 585         if (error)
 586                 return error;
 587
 588         switch (mode) {
 589         case FALLOC_FL_ZERO_RANGE:
 590         case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
 591                 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
 592                                             GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
 593                 break;
 594         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
 595                 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
 596                                              GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
 597                 break;
 598         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
 599                 error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
 600                                              GFP_KERNEL, 0);
 601                 break;
 602         default:
 603                 return -EOPNOTSUPP;
 604         }
 605         if (error)
 606                 return error;
 607
 608         /*
 609          * Invalidate the page cache again; if someone wandered in and dirtied
 610          * a page, we just discard it - userspace has no way of knowing whether
 611          * the write happened before or after discard completing...
 612          */
 613         return truncate_bdev_range(bdev, file->f_mode, start, end);
 614 }
 615
 616 const struct file_operations def_blk_fops = {
 617         .open           = blkdev_open,
 618         .release        = blkdev_close,
 619         .llseek         = blkdev_llseek,
 620         .read_iter      = blkdev_read_iter,
 621         .write_iter     = blkdev_write_iter,
 622         .iopoll         = blkdev_iopoll,
 623         .mmap           = generic_file_mmap,
 624         .fsync          = blkdev_fsync,
 625         .unlocked_ioctl = block_ioctl,
 626 #ifdef CONFIG_COMPAT
 627         .compat_ioctl   = compat_blkdev_ioctl,
 628 #endif
 629         .splice_read    = generic_file_splice_read,
 630         .splice_write   = iter_file_splice_write,
 631         .fallocate      = blkdev_fallocate,
 632 };
 633
 634 static __init int blkdev_init(void)
 635 {
 636         return bioset_init(&blkdev_dio_pool, 4,
 637                                 offsetof(struct blkdev_dio, bio),
 638                                 BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
 639 }
 640 module_init(blkdev_init);