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 8 #include <linux/init.h> 9 #include <linux/mm.h> 10 #include <linux/slab.h> 11 #include <linux/kmod.h> 12 #include <linux/major.h> 13 #include <linux/device_cgroup.h> 14 #include <linux/blkdev.h> 15 #include <linux/blk-integrity.h> 16 #include <linux/backing-dev.h> 17 #include <linux/module.h> 18 #include <linux/blkpg.h> 19 #include <linux/magic.h> 20 #include <linux/buffer_head.h> 21 #include <linux/swap.h> 22 #include <linux/writeback.h> 23 #include <linux/mount.h> 24 #include <linux/pseudo_fs.h> 25 #include <linux/uio.h> 26 #include <linux/namei.h> 27 #include <linux/part_stat.h> 28 #include <linux/uaccess.h> 29 #include <linux/stat.h> 30 #include "../fs/internal.h" 31 #include "blk.h" 32 33 /* Should we allow writing to mounted block devices? */ 34 static bool bdev_allow_write_mounted = IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED); 35 36 struct bdev_inode { 37 struct block_device bdev; 38 struct inode vfs_inode; 39 }; 40 41 static inline struct bdev_inode *BDEV_I(struct inode *inode) 42 { 43 return container_of(inode, struct bdev_inode, vfs_inode); 44 } 45 46 struct block_device *I_BDEV(struct inode *inode) 47 { 48 return &BDEV_I(inode)->bdev; 49 } 50 EXPORT_SYMBOL(I_BDEV); 51 52 struct block_device *file_bdev(struct file *bdev_file) 53 { 54 return I_BDEV(bdev_file->f_mapping->host); 55 } 56 EXPORT_SYMBOL(file_bdev); 57 58 static void bdev_write_inode(struct block_device *bdev) 59 { 60 struct inode *inode = bdev->bd_inode; 61 int ret; 62 63 spin_lock(&inode->i_lock); 64 while (inode->i_state & I_DIRTY) { 65 spin_unlock(&inode->i_lock); 66 ret = write_inode_now(inode, true); 67 if (ret) 68 pr_warn_ratelimited( 69 "VFS: Dirty inode writeback failed for block device %pg (err=%d).\n", 70 bdev, ret); 71 spin_lock(&inode->i_lock); 72 } 73 spin_unlock(&inode->i_lock); 74 } 75 76 /* Kill _all_ buffers and pagecache , dirty or not.. */ 77 static void kill_bdev(struct block_device *bdev) 78 { 79 struct address_space *mapping = bdev->bd_inode->i_mapping; 80 81 if (mapping_empty(mapping)) 82 return; 83 84 invalidate_bh_lrus(); 85 truncate_inode_pages(mapping, 0); 86 } 87 88 /* Invalidate clean unused buffers and pagecache. */ 89 void invalidate_bdev(struct block_device *bdev) 90 { 91 struct address_space *mapping = bdev->bd_inode->i_mapping; 92 93 if (mapping->nrpages) { 94 invalidate_bh_lrus(); 95 lru_add_drain_all(); /* make sure all lru add caches are flushed */ 96 invalidate_mapping_pages(mapping, 0, -1); 97 } 98 } 99 EXPORT_SYMBOL(invalidate_bdev); 100 101 /* 102 * Drop all buffers & page cache for given bdev range. This function bails 103 * with error if bdev has other exclusive owner (such as filesystem). 104 */ 105 int truncate_bdev_range(struct block_device *bdev, blk_mode_t mode, 106 loff_t lstart, loff_t lend) 107 { 108 /* 109 * If we don't hold exclusive handle for the device, upgrade to it 110 * while we discard the buffer cache to avoid discarding buffers 111 * under live filesystem. 112 */ 113 if (!(mode & BLK_OPEN_EXCL)) { 114 int err = bd_prepare_to_claim(bdev, truncate_bdev_range, NULL); 115 if (err) 116 goto invalidate; 117 } 118 119 truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend); 120 if (!(mode & BLK_OPEN_EXCL)) 121 bd_abort_claiming(bdev, truncate_bdev_range); 122 return 0; 123 124 invalidate: 125 /* 126 * Someone else has handle exclusively open. Try invalidating instead. 127 * The 'end' argument is inclusive so the rounding is safe. 128 */ 129 return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping, 130 lstart >> PAGE_SHIFT, 131 lend >> PAGE_SHIFT); 132 } 133 134 static void set_init_blocksize(struct block_device *bdev) 135 { 136 unsigned int bsize = bdev_logical_block_size(bdev); 137 loff_t size = i_size_read(bdev->bd_inode); 138 139 while (bsize < PAGE_SIZE) { 140 if (size & bsize) 141 break; 142 bsize <<= 1; 143 } 144 bdev->bd_inode->i_blkbits = blksize_bits(bsize); 145 } 146 147 int set_blocksize(struct block_device *bdev, int size) 148 { 149 /* Size must be a power of two, and between 512 and PAGE_SIZE */ 150 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size)) 151 return -EINVAL; 152 153 /* Size cannot be smaller than the size supported by the device */ 154 if (size < bdev_logical_block_size(bdev)) 155 return -EINVAL; 156 157 /* Don't change the size if it is same as current */ 158 if (bdev->bd_inode->i_blkbits != blksize_bits(size)) { 159 sync_blockdev(bdev); 160 bdev->bd_inode->i_blkbits = blksize_bits(size); 161 kill_bdev(bdev); 162 } 163 return 0; 164 } 165 166 EXPORT_SYMBOL(set_blocksize); 167 168 int sb_set_blocksize(struct super_block *sb, int size) 169 { 170 if (set_blocksize(sb->s_bdev, size)) 171 return 0; 172 /* If we get here, we know size is power of two 173 * and it's value is between 512 and PAGE_SIZE */ 174 sb->s_blocksize = size; 175 sb->s_blocksize_bits = blksize_bits(size); 176 return sb->s_blocksize; 177 } 178 179 EXPORT_SYMBOL(sb_set_blocksize); 180 181 int sb_min_blocksize(struct super_block *sb, int size) 182 { 183 int minsize = bdev_logical_block_size(sb->s_bdev); 184 if (size < minsize) 185 size = minsize; 186 return sb_set_blocksize(sb, size); 187 } 188 189 EXPORT_SYMBOL(sb_min_blocksize); 190 191 int sync_blockdev_nowait(struct block_device *bdev) 192 { 193 if (!bdev) 194 return 0; 195 return filemap_flush(bdev->bd_inode->i_mapping); 196 } 197 EXPORT_SYMBOL_GPL(sync_blockdev_nowait); 198 199 /* 200 * Write out and wait upon all the dirty data associated with a block 201 * device via its mapping. Does not take the superblock lock. 202 */ 203 int sync_blockdev(struct block_device *bdev) 204 { 205 if (!bdev) 206 return 0; 207 return filemap_write_and_wait(bdev->bd_inode->i_mapping); 208 } 209 EXPORT_SYMBOL(sync_blockdev); 210 211 int sync_blockdev_range(struct block_device *bdev, loff_t lstart, loff_t lend) 212 { 213 return filemap_write_and_wait_range(bdev->bd_inode->i_mapping, 214 lstart, lend); 215 } 216 EXPORT_SYMBOL(sync_blockdev_range); 217 218 /** 219 * bdev_freeze - lock a filesystem and force it into a consistent state 220 * @bdev: blockdevice to lock 221 * 222 * If a superblock is found on this device, we take the s_umount semaphore 223 * on it to make sure nobody unmounts until the snapshot creation is done. 224 * The reference counter (bd_fsfreeze_count) guarantees that only the last 225 * unfreeze process can unfreeze the frozen filesystem actually when multiple 226 * freeze requests arrive simultaneously. It counts up in bdev_freeze() and 227 * count down in bdev_thaw(). When it becomes 0, thaw_bdev() will unfreeze 228 * actually. 229 * 230 * Return: On success zero is returned, negative error code on failure. 231 */ 232 int bdev_freeze(struct block_device *bdev) 233 { 234 int error = 0; 235 236 mutex_lock(&bdev->bd_fsfreeze_mutex); 237 238 if (atomic_inc_return(&bdev->bd_fsfreeze_count) > 1) { 239 mutex_unlock(&bdev->bd_fsfreeze_mutex); 240 return 0; 241 } 242 243 mutex_lock(&bdev->bd_holder_lock); 244 if (bdev->bd_holder_ops && bdev->bd_holder_ops->freeze) { 245 error = bdev->bd_holder_ops->freeze(bdev); 246 lockdep_assert_not_held(&bdev->bd_holder_lock); 247 } else { 248 mutex_unlock(&bdev->bd_holder_lock); 249 error = sync_blockdev(bdev); 250 } 251 252 if (error) 253 atomic_dec(&bdev->bd_fsfreeze_count); 254 255 mutex_unlock(&bdev->bd_fsfreeze_mutex); 256 return error; 257 } 258 EXPORT_SYMBOL(bdev_freeze); 259 260 /** 261 * bdev_thaw - unlock filesystem 262 * @bdev: blockdevice to unlock 263 * 264 * Unlocks the filesystem and marks it writeable again after bdev_freeze(). 265 * 266 * Return: On success zero is returned, negative error code on failure. 267 */ 268 int bdev_thaw(struct block_device *bdev) 269 { 270 int error = -EINVAL, nr_freeze; 271 272 mutex_lock(&bdev->bd_fsfreeze_mutex); 273 274 /* 275 * If this returns < 0 it means that @bd_fsfreeze_count was 276 * already 0 and no decrement was performed. 277 */ 278 nr_freeze = atomic_dec_if_positive(&bdev->bd_fsfreeze_count); 279 if (nr_freeze < 0) 280 goto out; 281 282 error = 0; 283 if (nr_freeze > 0) 284 goto out; 285 286 mutex_lock(&bdev->bd_holder_lock); 287 if (bdev->bd_holder_ops && bdev->bd_holder_ops->thaw) { 288 error = bdev->bd_holder_ops->thaw(bdev); 289 lockdep_assert_not_held(&bdev->bd_holder_lock); 290 } else { 291 mutex_unlock(&bdev->bd_holder_lock); 292 } 293 294 if (error) 295 atomic_inc(&bdev->bd_fsfreeze_count); 296 out: 297 mutex_unlock(&bdev->bd_fsfreeze_mutex); 298 return error; 299 } 300 EXPORT_SYMBOL(bdev_thaw); 301 302 /* 303 * pseudo-fs 304 */ 305 306 static __cacheline_aligned_in_smp DEFINE_MUTEX(bdev_lock); 307 static struct kmem_cache *bdev_cachep __ro_after_init; 308 309 static struct inode *bdev_alloc_inode(struct super_block *sb) 310 { 311 struct bdev_inode *ei = alloc_inode_sb(sb, bdev_cachep, GFP_KERNEL); 312 313 if (!ei) 314 return NULL; 315 memset(&ei->bdev, 0, sizeof(ei->bdev)); 316 return &ei->vfs_inode; 317 } 318 319 static void bdev_free_inode(struct inode *inode) 320 { 321 struct block_device *bdev = I_BDEV(inode); 322 323 free_percpu(bdev->bd_stats); 324 kfree(bdev->bd_meta_info); 325 326 if (!bdev_is_partition(bdev)) { 327 if (bdev->bd_disk && bdev->bd_disk->bdi) 328 bdi_put(bdev->bd_disk->bdi); 329 kfree(bdev->bd_disk); 330 } 331 332 if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR) 333 blk_free_ext_minor(MINOR(bdev->bd_dev)); 334 335 kmem_cache_free(bdev_cachep, BDEV_I(inode)); 336 } 337 338 static void init_once(void *data) 339 { 340 struct bdev_inode *ei = data; 341 342 inode_init_once(&ei->vfs_inode); 343 } 344 345 static void bdev_evict_inode(struct inode *inode) 346 { 347 truncate_inode_pages_final(&inode->i_data); 348 invalidate_inode_buffers(inode); /* is it needed here? */ 349 clear_inode(inode); 350 } 351 352 static const struct super_operations bdev_sops = { 353 .statfs = simple_statfs, 354 .alloc_inode = bdev_alloc_inode, 355 .free_inode = bdev_free_inode, 356 .drop_inode = generic_delete_inode, 357 .evict_inode = bdev_evict_inode, 358 }; 359 360 static int bd_init_fs_context(struct fs_context *fc) 361 { 362 struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC); 363 if (!ctx) 364 return -ENOMEM; 365 fc->s_iflags |= SB_I_CGROUPWB; 366 ctx->ops = &bdev_sops; 367 return 0; 368 } 369 370 static struct file_system_type bd_type = { 371 .name = "bdev", 372 .init_fs_context = bd_init_fs_context, 373 .kill_sb = kill_anon_super, 374 }; 375 376 struct super_block *blockdev_superblock __ro_after_init; 377 struct vfsmount *blockdev_mnt __ro_after_init; 378 EXPORT_SYMBOL_GPL(blockdev_superblock); 379 380 void __init bdev_cache_init(void) 381 { 382 int err; 383 384 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode), 385 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| 386 SLAB_ACCOUNT|SLAB_PANIC), 387 init_once); 388 err = register_filesystem(&bd_type); 389 if (err) 390 panic("Cannot register bdev pseudo-fs"); 391 blockdev_mnt = kern_mount(&bd_type); 392 if (IS_ERR(blockdev_mnt)) 393 panic("Cannot create bdev pseudo-fs"); 394 blockdev_superblock = blockdev_mnt->mnt_sb; /* For writeback */ 395 } 396 397 struct block_device *bdev_alloc(struct gendisk *disk, u8 partno) 398 { 399 struct block_device *bdev; 400 struct inode *inode; 401 402 inode = new_inode(blockdev_superblock); 403 if (!inode) 404 return NULL; 405 inode->i_mode = S_IFBLK; 406 inode->i_rdev = 0; 407 inode->i_data.a_ops = &def_blk_aops; 408 mapping_set_gfp_mask(&inode->i_data, GFP_USER); 409 410 bdev = I_BDEV(inode); 411 mutex_init(&bdev->bd_fsfreeze_mutex); 412 spin_lock_init(&bdev->bd_size_lock); 413 mutex_init(&bdev->bd_holder_lock); 414 bdev->bd_partno = partno; 415 bdev->bd_inode = inode; 416 bdev->bd_queue = disk->queue; 417 if (partno) 418 bdev->bd_has_submit_bio = disk->part0->bd_has_submit_bio; 419 else 420 bdev->bd_has_submit_bio = false; 421 bdev->bd_stats = alloc_percpu(struct disk_stats); 422 if (!bdev->bd_stats) { 423 iput(inode); 424 return NULL; 425 } 426 bdev->bd_disk = disk; 427 return bdev; 428 } 429 430 void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors) 431 { 432 spin_lock(&bdev->bd_size_lock); 433 i_size_write(bdev->bd_inode, (loff_t)sectors << SECTOR_SHIFT); 434 bdev->bd_nr_sectors = sectors; 435 spin_unlock(&bdev->bd_size_lock); 436 } 437 438 void bdev_add(struct block_device *bdev, dev_t dev) 439 { 440 if (bdev_stable_writes(bdev)) 441 mapping_set_stable_writes(bdev->bd_inode->i_mapping); 442 bdev->bd_dev = dev; 443 bdev->bd_inode->i_rdev = dev; 444 bdev->bd_inode->i_ino = dev; 445 insert_inode_hash(bdev->bd_inode); 446 } 447 448 long nr_blockdev_pages(void) 449 { 450 struct inode *inode; 451 long ret = 0; 452 453 spin_lock(&blockdev_superblock->s_inode_list_lock); 454 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) 455 ret += inode->i_mapping->nrpages; 456 spin_unlock(&blockdev_superblock->s_inode_list_lock); 457 458 return ret; 459 } 460 461 /** 462 * bd_may_claim - test whether a block device can be claimed 463 * @bdev: block device of interest 464 * @holder: holder trying to claim @bdev 465 * @hops: holder ops 466 * 467 * Test whether @bdev can be claimed by @holder. 468 * 469 * RETURNS: 470 * %true if @bdev can be claimed, %false otherwise. 471 */ 472 static bool bd_may_claim(struct block_device *bdev, void *holder, 473 const struct blk_holder_ops *hops) 474 { 475 struct block_device *whole = bdev_whole(bdev); 476 477 lockdep_assert_held(&bdev_lock); 478 479 if (bdev->bd_holder) { 480 /* 481 * The same holder can always re-claim. 482 */ 483 if (bdev->bd_holder == holder) { 484 if (WARN_ON_ONCE(bdev->bd_holder_ops != hops)) 485 return false; 486 return true; 487 } 488 return false; 489 } 490 491 /* 492 * If the whole devices holder is set to bd_may_claim, a partition on 493 * the device is claimed, but not the whole device. 494 */ 495 if (whole != bdev && 496 whole->bd_holder && whole->bd_holder != bd_may_claim) 497 return false; 498 return true; 499 } 500 501 /** 502 * bd_prepare_to_claim - claim a block device 503 * @bdev: block device of interest 504 * @holder: holder trying to claim @bdev 505 * @hops: holder ops. 506 * 507 * Claim @bdev. This function fails if @bdev is already claimed by another 508 * holder and waits if another claiming is in progress. return, the caller 509 * has ownership of bd_claiming and bd_holder[s]. 510 * 511 * RETURNS: 512 * 0 if @bdev can be claimed, -EBUSY otherwise. 513 */ 514 int bd_prepare_to_claim(struct block_device *bdev, void *holder, 515 const struct blk_holder_ops *hops) 516 { 517 struct block_device *whole = bdev_whole(bdev); 518 519 if (WARN_ON_ONCE(!holder)) 520 return -EINVAL; 521 retry: 522 mutex_lock(&bdev_lock); 523 /* if someone else claimed, fail */ 524 if (!bd_may_claim(bdev, holder, hops)) { 525 mutex_unlock(&bdev_lock); 526 return -EBUSY; 527 } 528 529 /* if claiming is already in progress, wait for it to finish */ 530 if (whole->bd_claiming) { 531 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0); 532 DEFINE_WAIT(wait); 533 534 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); 535 mutex_unlock(&bdev_lock); 536 schedule(); 537 finish_wait(wq, &wait); 538 goto retry; 539 } 540 541 /* yay, all mine */ 542 whole->bd_claiming = holder; 543 mutex_unlock(&bdev_lock); 544 return 0; 545 } 546 EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */ 547 548 static void bd_clear_claiming(struct block_device *whole, void *holder) 549 { 550 lockdep_assert_held(&bdev_lock); 551 /* tell others that we're done */ 552 BUG_ON(whole->bd_claiming != holder); 553 whole->bd_claiming = NULL; 554 wake_up_bit(&whole->bd_claiming, 0); 555 } 556 557 /** 558 * bd_finish_claiming - finish claiming of a block device 559 * @bdev: block device of interest 560 * @holder: holder that has claimed @bdev 561 * @hops: block device holder operations 562 * 563 * Finish exclusive open of a block device. Mark the device as exlusively 564 * open by the holder and wake up all waiters for exclusive open to finish. 565 */ 566 static void bd_finish_claiming(struct block_device *bdev, void *holder, 567 const struct blk_holder_ops *hops) 568 { 569 struct block_device *whole = bdev_whole(bdev); 570 571 mutex_lock(&bdev_lock); 572 BUG_ON(!bd_may_claim(bdev, holder, hops)); 573 /* 574 * Note that for a whole device bd_holders will be incremented twice, 575 * and bd_holder will be set to bd_may_claim before being set to holder 576 */ 577 whole->bd_holders++; 578 whole->bd_holder = bd_may_claim; 579 bdev->bd_holders++; 580 mutex_lock(&bdev->bd_holder_lock); 581 bdev->bd_holder = holder; 582 bdev->bd_holder_ops = hops; 583 mutex_unlock(&bdev->bd_holder_lock); 584 bd_clear_claiming(whole, holder); 585 mutex_unlock(&bdev_lock); 586 587 if (hops && hops->get_holder) 588 hops->get_holder(holder); 589 } 590 591 /** 592 * bd_abort_claiming - abort claiming of a block device 593 * @bdev: block device of interest 594 * @holder: holder that has claimed @bdev 595 * 596 * Abort claiming of a block device when the exclusive open failed. This can be 597 * also used when exclusive open is not actually desired and we just needed 598 * to block other exclusive openers for a while. 599 */ 600 void bd_abort_claiming(struct block_device *bdev, void *holder) 601 { 602 mutex_lock(&bdev_lock); 603 bd_clear_claiming(bdev_whole(bdev), holder); 604 mutex_unlock(&bdev_lock); 605 } 606 EXPORT_SYMBOL(bd_abort_claiming); 607 608 static void bd_end_claim(struct block_device *bdev, void *holder) 609 { 610 struct block_device *whole = bdev_whole(bdev); 611 const struct blk_holder_ops *hops = bdev->bd_holder_ops; 612 bool unblock = false; 613 614 /* 615 * Release a claim on the device. The holder fields are protected with 616 * bdev_lock. open_mutex is used to synchronize disk_holder unlinking. 617 */ 618 mutex_lock(&bdev_lock); 619 WARN_ON_ONCE(bdev->bd_holder != holder); 620 WARN_ON_ONCE(--bdev->bd_holders < 0); 621 WARN_ON_ONCE(--whole->bd_holders < 0); 622 if (!bdev->bd_holders) { 623 mutex_lock(&bdev->bd_holder_lock); 624 bdev->bd_holder = NULL; 625 bdev->bd_holder_ops = NULL; 626 mutex_unlock(&bdev->bd_holder_lock); 627 if (bdev->bd_write_holder) 628 unblock = true; 629 } 630 if (!whole->bd_holders) 631 whole->bd_holder = NULL; 632 mutex_unlock(&bdev_lock); 633 634 if (hops && hops->put_holder) 635 hops->put_holder(holder); 636 637 /* 638 * If this was the last claim, remove holder link and unblock evpoll if 639 * it was a write holder. 640 */ 641 if (unblock) { 642 disk_unblock_events(bdev->bd_disk); 643 bdev->bd_write_holder = false; 644 } 645 } 646 647 static void blkdev_flush_mapping(struct block_device *bdev) 648 { 649 WARN_ON_ONCE(bdev->bd_holders); 650 sync_blockdev(bdev); 651 kill_bdev(bdev); 652 bdev_write_inode(bdev); 653 } 654 655 static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode) 656 { 657 struct gendisk *disk = bdev->bd_disk; 658 int ret; 659 660 if (disk->fops->open) { 661 ret = disk->fops->open(disk, mode); 662 if (ret) { 663 /* avoid ghost partitions on a removed medium */ 664 if (ret == -ENOMEDIUM && 665 test_bit(GD_NEED_PART_SCAN, &disk->state)) 666 bdev_disk_changed(disk, true); 667 return ret; 668 } 669 } 670 671 if (!atomic_read(&bdev->bd_openers)) 672 set_init_blocksize(bdev); 673 if (test_bit(GD_NEED_PART_SCAN, &disk->state)) 674 bdev_disk_changed(disk, false); 675 atomic_inc(&bdev->bd_openers); 676 return 0; 677 } 678 679 static void blkdev_put_whole(struct block_device *bdev) 680 { 681 if (atomic_dec_and_test(&bdev->bd_openers)) 682 blkdev_flush_mapping(bdev); 683 if (bdev->bd_disk->fops->release) 684 bdev->bd_disk->fops->release(bdev->bd_disk); 685 } 686 687 static int blkdev_get_part(struct block_device *part, blk_mode_t mode) 688 { 689 struct gendisk *disk = part->bd_disk; 690 int ret; 691 692 ret = blkdev_get_whole(bdev_whole(part), mode); 693 if (ret) 694 return ret; 695 696 ret = -ENXIO; 697 if (!bdev_nr_sectors(part)) 698 goto out_blkdev_put; 699 700 if (!atomic_read(&part->bd_openers)) { 701 disk->open_partitions++; 702 set_init_blocksize(part); 703 } 704 atomic_inc(&part->bd_openers); 705 return 0; 706 707 out_blkdev_put: 708 blkdev_put_whole(bdev_whole(part)); 709 return ret; 710 } 711 712 int bdev_permission(dev_t dev, blk_mode_t mode, void *holder) 713 { 714 int ret; 715 716 ret = devcgroup_check_permission(DEVCG_DEV_BLOCK, 717 MAJOR(dev), MINOR(dev), 718 ((mode & BLK_OPEN_READ) ? DEVCG_ACC_READ : 0) | 719 ((mode & BLK_OPEN_WRITE) ? DEVCG_ACC_WRITE : 0)); 720 if (ret) 721 return ret; 722 723 /* Blocking writes requires exclusive opener */ 724 if (mode & BLK_OPEN_RESTRICT_WRITES && !holder) 725 return -EINVAL; 726 727 /* 728 * We're using error pointers to indicate to ->release() when we 729 * failed to open that block device. Also this doesn't make sense. 730 */ 731 if (WARN_ON_ONCE(IS_ERR(holder))) 732 return -EINVAL; 733 734 return 0; 735 } 736 737 static void blkdev_put_part(struct block_device *part) 738 { 739 struct block_device *whole = bdev_whole(part); 740 741 if (atomic_dec_and_test(&part->bd_openers)) { 742 blkdev_flush_mapping(part); 743 whole->bd_disk->open_partitions--; 744 } 745 blkdev_put_whole(whole); 746 } 747 748 struct block_device *blkdev_get_no_open(dev_t dev) 749 { 750 struct block_device *bdev; 751 struct inode *inode; 752 753 inode = ilookup(blockdev_superblock, dev); 754 if (!inode && IS_ENABLED(CONFIG_BLOCK_LEGACY_AUTOLOAD)) { 755 blk_request_module(dev); 756 inode = ilookup(blockdev_superblock, dev); 757 if (inode) 758 pr_warn_ratelimited( 759 "block device autoloading is deprecated and will be removed.\n"); 760 } 761 if (!inode) 762 return NULL; 763 764 /* switch from the inode reference to a device mode one: */ 765 bdev = &BDEV_I(inode)->bdev; 766 if (!kobject_get_unless_zero(&bdev->bd_device.kobj)) 767 bdev = NULL; 768 iput(inode); 769 return bdev; 770 } 771 772 void blkdev_put_no_open(struct block_device *bdev) 773 { 774 put_device(&bdev->bd_device); 775 } 776 777 static bool bdev_writes_blocked(struct block_device *bdev) 778 { 779 return bdev->bd_writers == -1; 780 } 781 782 static void bdev_block_writes(struct block_device *bdev) 783 { 784 bdev->bd_writers = -1; 785 } 786 787 static void bdev_unblock_writes(struct block_device *bdev) 788 { 789 bdev->bd_writers = 0; 790 } 791 792 static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode) 793 { 794 if (bdev_allow_write_mounted) 795 return true; 796 /* Writes blocked? */ 797 if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev)) 798 return false; 799 if (mode & BLK_OPEN_RESTRICT_WRITES && bdev->bd_writers > 0) 800 return false; 801 return true; 802 } 803 804 static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode) 805 { 806 if (bdev_allow_write_mounted) 807 return; 808 809 /* Claim exclusive or shared write access. */ 810 if (mode & BLK_OPEN_RESTRICT_WRITES) 811 bdev_block_writes(bdev); 812 else if (mode & BLK_OPEN_WRITE) 813 bdev->bd_writers++; 814 } 815 816 static void bdev_yield_write_access(struct file *bdev_file) 817 { 818 struct block_device *bdev; 819 820 if (bdev_allow_write_mounted) 821 return; 822 823 bdev = file_bdev(bdev_file); 824 /* Yield exclusive or shared write access. */ 825 if (bdev_file->f_mode & FMODE_WRITE) { 826 if (bdev_writes_blocked(bdev)) 827 bdev_unblock_writes(bdev); 828 else 829 bdev->bd_writers--; 830 } 831 } 832 833 /** 834 * bdev_open - open a block device 835 * @bdev: block device to open 836 * @mode: open mode (BLK_OPEN_*) 837 * @holder: exclusive holder identifier 838 * @hops: holder operations 839 * @bdev_file: file for the block device 840 * 841 * Open the block device. If @holder is not %NULL, the block device is opened 842 * with exclusive access. Exclusive opens may nest for the same @holder. 843 * 844 * CONTEXT: 845 * Might sleep. 846 * 847 * RETURNS: 848 * zero on success, -errno on failure. 849 */ 850 int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder, 851 const struct blk_holder_ops *hops, struct file *bdev_file) 852 { 853 bool unblock_events = true; 854 struct gendisk *disk = bdev->bd_disk; 855 int ret; 856 857 if (holder) { 858 mode |= BLK_OPEN_EXCL; 859 ret = bd_prepare_to_claim(bdev, holder, hops); 860 if (ret) 861 return ret; 862 } else { 863 if (WARN_ON_ONCE(mode & BLK_OPEN_EXCL)) 864 return -EIO; 865 } 866 867 disk_block_events(disk); 868 869 mutex_lock(&disk->open_mutex); 870 ret = -ENXIO; 871 if (!disk_live(disk)) 872 goto abort_claiming; 873 if (!try_module_get(disk->fops->owner)) 874 goto abort_claiming; 875 ret = -EBUSY; 876 if (!bdev_may_open(bdev, mode)) 877 goto abort_claiming; 878 if (bdev_is_partition(bdev)) 879 ret = blkdev_get_part(bdev, mode); 880 else 881 ret = blkdev_get_whole(bdev, mode); 882 if (ret) 883 goto put_module; 884 bdev_claim_write_access(bdev, mode); 885 if (holder) { 886 bd_finish_claiming(bdev, holder, hops); 887 888 /* 889 * Block event polling for write claims if requested. Any write 890 * holder makes the write_holder state stick until all are 891 * released. This is good enough and tracking individual 892 * writeable reference is too fragile given the way @mode is 893 * used in blkdev_get/put(). 894 */ 895 if ((mode & BLK_OPEN_WRITE) && !bdev->bd_write_holder && 896 (disk->event_flags & DISK_EVENT_FLAG_BLOCK_ON_EXCL_WRITE)) { 897 bdev->bd_write_holder = true; 898 unblock_events = false; 899 } 900 } 901 mutex_unlock(&disk->open_mutex); 902 903 if (unblock_events) 904 disk_unblock_events(disk); 905 906 bdev_file->f_flags |= O_LARGEFILE; 907 bdev_file->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT; 908 if (bdev_nowait(bdev)) 909 bdev_file->f_mode |= FMODE_NOWAIT; 910 bdev_file->f_mapping = bdev->bd_inode->i_mapping; 911 bdev_file->f_wb_err = filemap_sample_wb_err(bdev_file->f_mapping); 912 bdev_file->private_data = holder; 913 914 return 0; 915 put_module: 916 module_put(disk->fops->owner); 917 abort_claiming: 918 if (holder) 919 bd_abort_claiming(bdev, holder); 920 mutex_unlock(&disk->open_mutex); 921 disk_unblock_events(disk); 922 return ret; 923 } 924 925 /* 926 * If BLK_OPEN_WRITE_IOCTL is set then this is a historical quirk 927 * associated with the floppy driver where it has allowed ioctls if the 928 * file was opened for writing, but does not allow reads or writes. 929 * Make sure that this quirk is reflected in @f_flags. 930 * 931 * It can also happen if a block device is opened as O_RDWR | O_WRONLY. 932 */ 933 static unsigned blk_to_file_flags(blk_mode_t mode) 934 { 935 unsigned int flags = 0; 936 937 if ((mode & (BLK_OPEN_READ | BLK_OPEN_WRITE)) == 938 (BLK_OPEN_READ | BLK_OPEN_WRITE)) 939 flags |= O_RDWR; 940 else if (mode & BLK_OPEN_WRITE_IOCTL) 941 flags |= O_RDWR | O_WRONLY; 942 else if (mode & BLK_OPEN_WRITE) 943 flags |= O_WRONLY; 944 else if (mode & BLK_OPEN_READ) 945 flags |= O_RDONLY; /* homeopathic, because O_RDONLY is 0 */ 946 else 947 WARN_ON_ONCE(true); 948 949 if (mode & BLK_OPEN_NDELAY) 950 flags |= O_NDELAY; 951 952 return flags; 953 } 954 955 struct file *bdev_file_open_by_dev(dev_t dev, blk_mode_t mode, void *holder, 956 const struct blk_holder_ops *hops) 957 { 958 struct file *bdev_file; 959 struct block_device *bdev; 960 unsigned int flags; 961 int ret; 962 963 ret = bdev_permission(dev, mode, holder); 964 if (ret) 965 return ERR_PTR(ret); 966 967 bdev = blkdev_get_no_open(dev); 968 if (!bdev) 969 return ERR_PTR(-ENXIO); 970 971 flags = blk_to_file_flags(mode); 972 bdev_file = alloc_file_pseudo_noaccount(bdev->bd_inode, 973 blockdev_mnt, "", flags | O_LARGEFILE, &def_blk_fops); 974 if (IS_ERR(bdev_file)) { 975 blkdev_put_no_open(bdev); 976 return bdev_file; 977 } 978 ihold(bdev->bd_inode); 979 980 ret = bdev_open(bdev, mode, holder, hops, bdev_file); 981 if (ret) { 982 /* We failed to open the block device. Let ->release() know. */ 983 bdev_file->private_data = ERR_PTR(ret); 984 fput(bdev_file); 985 return ERR_PTR(ret); 986 } 987 return bdev_file; 988 } 989 EXPORT_SYMBOL(bdev_file_open_by_dev); 990 991 struct file *bdev_file_open_by_path(const char *path, blk_mode_t mode, 992 void *holder, 993 const struct blk_holder_ops *hops) 994 { 995 struct file *file; 996 dev_t dev; 997 int error; 998 999 error = lookup_bdev(path, &dev); 1000 if (error) 1001 return ERR_PTR(error); 1002 1003 file = bdev_file_open_by_dev(dev, mode, holder, hops); 1004 if (!IS_ERR(file) && (mode & BLK_OPEN_WRITE)) { 1005 if (bdev_read_only(file_bdev(file))) { 1006 fput(file); 1007 file = ERR_PTR(-EACCES); 1008 } 1009 } 1010 1011 return file; 1012 } 1013 EXPORT_SYMBOL(bdev_file_open_by_path); 1014 1015 void bdev_release(struct file *bdev_file) 1016 { 1017 struct block_device *bdev = file_bdev(bdev_file); 1018 void *holder = bdev_file->private_data; 1019 struct gendisk *disk = bdev->bd_disk; 1020 1021 /* We failed to open that block device. */ 1022 if (IS_ERR(holder)) 1023 goto put_no_open; 1024 1025 /* 1026 * Sync early if it looks like we're the last one. If someone else 1027 * opens the block device between now and the decrement of bd_openers 1028 * then we did a sync that we didn't need to, but that's not the end 1029 * of the world and we want to avoid long (could be several minute) 1030 * syncs while holding the mutex. 1031 */ 1032 if (atomic_read(&bdev->bd_openers) == 1) 1033 sync_blockdev(bdev); 1034 1035 mutex_lock(&disk->open_mutex); 1036 bdev_yield_write_access(bdev_file); 1037 1038 if (holder) 1039 bd_end_claim(bdev, holder); 1040 1041 /* 1042 * Trigger event checking and tell drivers to flush MEDIA_CHANGE 1043 * event. This is to ensure detection of media removal commanded 1044 * from userland - e.g. eject(1). 1045 */ 1046 disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE); 1047 1048 if (bdev_is_partition(bdev)) 1049 blkdev_put_part(bdev); 1050 else 1051 blkdev_put_whole(bdev); 1052 mutex_unlock(&disk->open_mutex); 1053 1054 module_put(disk->fops->owner); 1055 put_no_open: 1056 blkdev_put_no_open(bdev); 1057 } 1058 1059 /** 1060 * lookup_bdev() - Look up a struct block_device by name. 1061 * @pathname: Name of the block device in the filesystem. 1062 * @dev: Pointer to the block device's dev_t, if found. 1063 * 1064 * Lookup the block device's dev_t at @pathname in the current 1065 * namespace if possible and return it in @dev. 1066 * 1067 * Context: May sleep. 1068 * Return: 0 if succeeded, negative errno otherwise. 1069 */ 1070 int lookup_bdev(const char *pathname, dev_t *dev) 1071 { 1072 struct inode *inode; 1073 struct path path; 1074 int error; 1075 1076 if (!pathname || !*pathname) 1077 return -EINVAL; 1078 1079 error = kern_path(pathname, LOOKUP_FOLLOW, &path); 1080 if (error) 1081 return error; 1082 1083 inode = d_backing_inode(path.dentry); 1084 error = -ENOTBLK; 1085 if (!S_ISBLK(inode->i_mode)) 1086 goto out_path_put; 1087 error = -EACCES; 1088 if (!may_open_dev(&path)) 1089 goto out_path_put; 1090 1091 *dev = inode->i_rdev; 1092 error = 0; 1093 out_path_put: 1094 path_put(&path); 1095 return error; 1096 } 1097 EXPORT_SYMBOL(lookup_bdev); 1098 1099 /** 1100 * bdev_mark_dead - mark a block device as dead 1101 * @bdev: block device to operate on 1102 * @surprise: indicate a surprise removal 1103 * 1104 * Tell the file system that this devices or media is dead. If @surprise is set 1105 * to %true the device or media is already gone, if not we are preparing for an 1106 * orderly removal. 1107 * 1108 * This calls into the file system, which then typicall syncs out all dirty data 1109 * and writes back inodes and then invalidates any cached data in the inodes on 1110 * the file system. In addition we also invalidate the block device mapping. 1111 */ 1112 void bdev_mark_dead(struct block_device *bdev, bool surprise) 1113 { 1114 mutex_lock(&bdev->bd_holder_lock); 1115 if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead) 1116 bdev->bd_holder_ops->mark_dead(bdev, surprise); 1117 else { 1118 mutex_unlock(&bdev->bd_holder_lock); 1119 sync_blockdev(bdev); 1120 } 1121 1122 invalidate_bdev(bdev); 1123 } 1124 /* 1125 * New drivers should not use this directly. There are some drivers however 1126 * that needs this for historical reasons. For example, the DASD driver has 1127 * historically had a shutdown to offline mode that doesn't actually remove the 1128 * gendisk that otherwise looks a lot like a safe device removal. 1129 */ 1130 EXPORT_SYMBOL_GPL(bdev_mark_dead); 1131 1132 void sync_bdevs(bool wait) 1133 { 1134 struct inode *inode, *old_inode = NULL; 1135 1136 spin_lock(&blockdev_superblock->s_inode_list_lock); 1137 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) { 1138 struct address_space *mapping = inode->i_mapping; 1139 struct block_device *bdev; 1140 1141 spin_lock(&inode->i_lock); 1142 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) || 1143 mapping->nrpages == 0) { 1144 spin_unlock(&inode->i_lock); 1145 continue; 1146 } 1147 __iget(inode); 1148 spin_unlock(&inode->i_lock); 1149 spin_unlock(&blockdev_superblock->s_inode_list_lock); 1150 /* 1151 * We hold a reference to 'inode' so it couldn't have been 1152 * removed from s_inodes list while we dropped the 1153 * s_inode_list_lock We cannot iput the inode now as we can 1154 * be holding the last reference and we cannot iput it under 1155 * s_inode_list_lock. So we keep the reference and iput it 1156 * later. 1157 */ 1158 iput(old_inode); 1159 old_inode = inode; 1160 bdev = I_BDEV(inode); 1161 1162 mutex_lock(&bdev->bd_disk->open_mutex); 1163 if (!atomic_read(&bdev->bd_openers)) { 1164 ; /* skip */ 1165 } else if (wait) { 1166 /* 1167 * We keep the error status of individual mapping so 1168 * that applications can catch the writeback error using 1169 * fsync(2). See filemap_fdatawait_keep_errors() for 1170 * details. 1171 */ 1172 filemap_fdatawait_keep_errors(inode->i_mapping); 1173 } else { 1174 filemap_fdatawrite(inode->i_mapping); 1175 } 1176 mutex_unlock(&bdev->bd_disk->open_mutex); 1177 1178 spin_lock(&blockdev_superblock->s_inode_list_lock); 1179 } 1180 spin_unlock(&blockdev_superblock->s_inode_list_lock); 1181 iput(old_inode); 1182 } 1183 1184 /* 1185 * Handle STATX_DIOALIGN for block devices. 1186 * 1187 * Note that the inode passed to this is the inode of a block device node file, 1188 * not the block device's internal inode. Therefore it is *not* valid to use 1189 * I_BDEV() here; the block device has to be looked up by i_rdev instead. 1190 */ 1191 void bdev_statx_dioalign(struct inode *inode, struct kstat *stat) 1192 { 1193 struct block_device *bdev; 1194 1195 bdev = blkdev_get_no_open(inode->i_rdev); 1196 if (!bdev) 1197 return; 1198 1199 stat->dio_mem_align = bdev_dma_alignment(bdev) + 1; 1200 stat->dio_offset_align = bdev_logical_block_size(bdev); 1201 stat->result_mask |= STATX_DIOALIGN; 1202 1203 blkdev_put_no_open(bdev); 1204 } 1205 1206 static int __init setup_bdev_allow_write_mounted(char *str) 1207 { 1208 if (kstrtobool(str, &bdev_allow_write_mounted)) 1209 pr_warn("Invalid option string for bdev_allow_write_mounted:" 1210 " '%s'\n", str); 1211 return 1; 1212 } 1213 __setup("bdev_allow_write_mounted=", setup_bdev_allow_write_mounted); 1214