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
 247                 if (is_read) {
 248                         bio->bi_opf = REQ_OP_READ;
 249                         if (dio->should_dirty)
 250                                 bio_set_pages_dirty(bio);
 251                 } else {
 252                         bio->bi_opf = dio_bio_write_op(iocb);
 253                         task_io_account_write(bio->bi_iter.bi_size);
 254                 }
 255                 if (iocb->ki_flags & IOCB_NOWAIT)
 256                         bio->bi_opf |= REQ_NOWAIT;
 257
 258                 dio->size += bio->bi_iter.bi_size;
 259                 pos += bio->bi_iter.bi_size;
 260
 261                 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
 262                 if (!nr_pages) {
 263                         bool polled = false;
 264
 265                         if (iocb->ki_flags & IOCB_HIPRI) {
 266                                 bio_set_polled(bio, iocb);
 267                                 polled = true;
 268                         }
 269
 270                         qc = submit_bio(bio);
 271
 272                         if (polled)
 273                                 WRITE_ONCE(iocb->ki_cookie, qc);
 274                         break;
 275                 }
 276
 277                 if (!dio->multi_bio) {
 278                         /*
 279                          * AIO needs an extra reference to ensure the dio
 280                          * structure which is embedded into the first bio
 281                          * stays around.
 282                          */
 283                         if (!is_sync)
 284                                 bio_get(bio);
 285                         dio->multi_bio = true;
 286                         atomic_set(&dio->ref, 2);
 287                 } else {
 288                         atomic_inc(&dio->ref);
 289                 }
 290
 291                 submit_bio(bio);
 292                 bio = bio_alloc(GFP_KERNEL, nr_pages);
 293         }
 294
 295         if (!is_poll)
 296                 blk_finish_plug(&plug);
 297
 298         if (!is_sync)
 299                 return -EIOCBQUEUED;
 300
 301         for (;;) {
 302                 set_current_state(TASK_UNINTERRUPTIBLE);
 303                 if (!READ_ONCE(dio->waiter))
 304                         break;
 305
 306                 if (!(iocb->ki_flags & IOCB_HIPRI) ||
 307                     !blk_poll(bdev_get_queue(bdev), qc, true))
 308                         blk_io_schedule();
 309         }
 310         __set_current_state(TASK_RUNNING);
 311
 312         if (!ret)
 313                 ret = blk_status_to_errno(dio->bio.bi_status);
 314         if (likely(!ret))
 315                 ret = dio->size;
 316
 317         bio_put(&dio->bio);
 318         return ret;
 319 }
 320
 321 static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 322 {
 323         unsigned int nr_pages;
 324
 325         if (!iov_iter_count(iter))
 326                 return 0;
 327
 328         nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
 329         if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_VECS)
 330                 return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
 331
 332         return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
 333 }
 334
 335 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
 336 {
 337         return block_write_full_page(page, blkdev_get_block, wbc);
 338 }
 339
 340 static int blkdev_readpage(struct file * file, struct page * page)
 341 {
 342         return block_read_full_page(page, blkdev_get_block);
 343 }
 344
 345 static void blkdev_readahead(struct readahead_control *rac)
 346 {
 347         mpage_readahead(rac, blkdev_get_block);
 348 }
 349
 350 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
 351                 loff_t pos, unsigned len, unsigned flags, struct page **pagep,
 352                 void **fsdata)
 353 {
 354         return block_write_begin(mapping, pos, len, flags, pagep,
 355                                  blkdev_get_block);
 356 }
 357
 358 static int blkdev_write_end(struct file *file, struct address_space *mapping,
 359                 loff_t pos, unsigned len, unsigned copied, struct page *page,
 360                 void *fsdata)
 361 {
 362         int ret;
 363         ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
 364
 365         unlock_page(page);
 366         put_page(page);
 367
 368         return ret;
 369 }
 370
 371 static int blkdev_writepages(struct address_space *mapping,
 372                              struct writeback_control *wbc)
 373 {
 374         return generic_writepages(mapping, wbc);
 375 }
 376
 377 const struct address_space_operations def_blk_aops = {
 378         .set_page_dirty = __set_page_dirty_buffers,
 379         .readpage       = blkdev_readpage,
 380         .readahead      = blkdev_readahead,
 381         .writepage      = blkdev_writepage,
 382         .write_begin    = blkdev_write_begin,
 383         .write_end      = blkdev_write_end,
 384         .writepages     = blkdev_writepages,
 385         .direct_IO      = blkdev_direct_IO,
 386         .migratepage    = buffer_migrate_page_norefs,
 387         .is_dirty_writeback = buffer_check_dirty_writeback,
 388 };
 389
 390 /*
 391  * for a block special file file_inode(file)->i_size is zero
 392  * so we compute the size by hand (just as in block_read/write above)
 393  */
 394 static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
 395 {
 396         struct inode *bd_inode = bdev_file_inode(file);
 397         loff_t retval;
 398
 399         inode_lock(bd_inode);
 400         retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
 401         inode_unlock(bd_inode);
 402         return retval;
 403 }
 404
 405 static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
 406                 int datasync)
 407 {
 408         struct inode *bd_inode = bdev_file_inode(filp);
 409         struct block_device *bdev = I_BDEV(bd_inode);
 410         int error;
 411
 412         error = file_write_and_wait_range(filp, start, end);
 413         if (error)
 414                 return error;
 415
 416         /*
 417          * There is no need to serialise calls to blkdev_issue_flush with
 418          * i_mutex and doing so causes performance issues with concurrent
 419          * O_SYNC writers to a block device.
 420          */
 421         error = blkdev_issue_flush(bdev);
 422         if (error == -EOPNOTSUPP)
 423                 error = 0;
 424
 425         return error;
 426 }
 427
 428 static int blkdev_open(struct inode *inode, struct file *filp)
 429 {
 430         struct block_device *bdev;
 431
 432         /*
 433          * Preserve backwards compatibility and allow large file access
 434          * even if userspace doesn't ask for it explicitly. Some mkfs
 435          * binary needs it. We might want to drop this workaround
 436          * during an unstable branch.
 437          */
 438         filp->f_flags |= O_LARGEFILE;
 439         filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
 440
 441         if (filp->f_flags & O_NDELAY)
 442                 filp->f_mode |= FMODE_NDELAY;
 443         if (filp->f_flags & O_EXCL)
 444                 filp->f_mode |= FMODE_EXCL;
 445         if ((filp->f_flags & O_ACCMODE) == 3)
 446                 filp->f_mode |= FMODE_WRITE_IOCTL;
 447
 448         bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp);
 449         if (IS_ERR(bdev))
 450                 return PTR_ERR(bdev);
 451         filp->f_mapping = bdev->bd_inode->i_mapping;
 452         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 453         return 0;
 454 }
 455
 456 static int blkdev_close(struct inode *inode, struct file *filp)
 457 {
 458         struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
 459
 460         blkdev_put(bdev, filp->f_mode);
 461         return 0;
 462 }
 463
 464 static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 465 {
 466         struct block_device *bdev = I_BDEV(bdev_file_inode(file));
 467         fmode_t mode = file->f_mode;
 468
 469         /*
 470          * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
 471          * to updated it before every ioctl.
 472          */
 473         if (file->f_flags & O_NDELAY)
 474                 mode |= FMODE_NDELAY;
 475         else
 476                 mode &= ~FMODE_NDELAY;
 477
 478         return blkdev_ioctl(bdev, mode, cmd, arg);
 479 }
 480
 481 /*
 482  * Write data to the block device.  Only intended for the block device itself
 483  * and the raw driver which basically is a fake block device.
 484  *
 485  * Does not take i_mutex for the write and thus is not for general purpose
 486  * use.
 487  */
 488 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 489 {
 490         struct file *file = iocb->ki_filp;
 491         struct inode *bd_inode = bdev_file_inode(file);
 492         loff_t size = i_size_read(bd_inode);
 493         struct blk_plug plug;
 494         size_t shorted = 0;
 495         ssize_t ret;
 496
 497         if (bdev_read_only(I_BDEV(bd_inode)))
 498                 return -EPERM;
 499
 500         if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
 501                 return -ETXTBSY;
 502
 503         if (!iov_iter_count(from))
 504                 return 0;
 505
 506         if (iocb->ki_pos >= size)
 507                 return -ENOSPC;
 508
 509         if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
 510                 return -EOPNOTSUPP;
 511
 512         size -= iocb->ki_pos;
 513         if (iov_iter_count(from) > size) {
 514                 shorted = iov_iter_count(from) - size;
 515                 iov_iter_truncate(from, size);
 516         }
 517
 518         blk_start_plug(&plug);
 519         ret = __generic_file_write_iter(iocb, from);
 520         if (ret > 0)
 521                 ret = generic_write_sync(iocb, ret);
 522         iov_iter_reexpand(from, iov_iter_count(from) + shorted);
 523         blk_finish_plug(&plug);
 524         return ret;
 525 }
 526
 527 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 528 {
 529         struct file *file = iocb->ki_filp;
 530         struct inode *bd_inode = bdev_file_inode(file);
 531         loff_t size = i_size_read(bd_inode);
 532         loff_t pos = iocb->ki_pos;
 533         size_t shorted = 0;
 534         ssize_t ret;
 535
 536         if (pos >= size)
 537                 return 0;
 538
 539         size -= pos;
 540         if (iov_iter_count(to) > size) {
 541                 shorted = iov_iter_count(to) - size;
 542                 iov_iter_truncate(to, size);
 543         }
 544
 545         ret = generic_file_read_iter(iocb, to);
 546         iov_iter_reexpand(to, iov_iter_count(to) + shorted);
 547         return ret;
 548 }
 549
 550 #define BLKDEV_FALLOC_FL_SUPPORTED                                      \
 551                 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
 552                  FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
 553
 554 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 555                              loff_t len)
 556 {
 557         struct inode *inode = bdev_file_inode(file);
 558         struct block_device *bdev = I_BDEV(inode);
 559         loff_t end = start + len - 1;
 560         loff_t isize;
 561         int error;
 562
 563         /* Fail if we don't recognize the flags. */
 564         if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
 565                 return -EOPNOTSUPP;
 566
 567         /* Don't go off the end of the device. */
 568         isize = i_size_read(bdev->bd_inode);
 569         if (start >= isize)
 570                 return -EINVAL;
 571         if (end >= isize) {
 572                 if (mode & FALLOC_FL_KEEP_SIZE) {
 573                         len = isize - start;
 574                         end = start + len - 1;
 575                 } else
 576                         return -EINVAL;
 577         }
 578
 579         /*
 580          * Don't allow IO that isn't aligned to logical block size.
 581          */
 582         if ((start | len) & (bdev_logical_block_size(bdev) - 1))
 583                 return -EINVAL;
 584
 585         filemap_invalidate_lock(inode->i_mapping);
 586
 587         /* Invalidate the page cache, including dirty pages. */
 588         error = truncate_bdev_range(bdev, file->f_mode, start, end);
 589         if (error)
 590                 goto fail;
 591
 592         switch (mode) {
 593         case FALLOC_FL_ZERO_RANGE:
 594         case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
 595                 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
 596                                             GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
 597                 break;
 598         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
 599                 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
 600                                              GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
 601                 break;
 602         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
 603                 error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
 604                                              GFP_KERNEL, 0);
 605                 break;
 606         default:
 607                 error = -EOPNOTSUPP;
 608         }
 609
 610  fail:
 611         filemap_invalidate_unlock(inode->i_mapping);
 612         return error;
 613 }
 614
 615 const struct file_operations def_blk_fops = {
 616         .open           = blkdev_open,
 617         .release        = blkdev_close,
 618         .llseek         = blkdev_llseek,
 619         .read_iter      = blkdev_read_iter,
 620         .write_iter     = blkdev_write_iter,
 621         .iopoll         = blkdev_iopoll,
 622         .mmap           = generic_file_mmap,
 623         .fsync          = blkdev_fsync,
 624         .unlocked_ioctl = block_ioctl,
 625 #ifdef CONFIG_COMPAT
 626         .compat_ioctl   = compat_blkdev_ioctl,
 627 #endif
 628         .splice_read    = generic_file_splice_read,
 629         .splice_write   = iter_file_splice_write,
 630         .fallocate      = blkdev_fallocate,
 631 };
 632
 633 static __init int blkdev_init(void)
 634 {
 635         return bioset_init(&blkdev_dio_pool, 4,
 636                                 offsetof(struct blkdev_dio, bio),
 637                                 BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
 638 }
 639 module_init(blkdev_init);