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? */ 34static bool bdev_allow_write_mounted = IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED); 35 36struct bdev_inode { 37 struct block_device bdev; 38 struct inode vfs_inode; 39}; 40 41static inline struct bdev_inode *BDEV_I(struct inode *inode) 42{ 43 return container_of(inode, struct bdev_inode, vfs_inode); 44} 45 46struct block_device *I_BDEV(struct inode *inode) 47{ 48 return &BDEV_I(inode)->bdev; 49} 50EXPORT_SYMBOL(I_BDEV); 51 52struct block_device *file_bdev(struct file *bdev_file) 53{ 54 return I_BDEV(bdev_file->f_mapping->host); 55} 56EXPORT_SYMBOL(file_bdev); 57 58static 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.. */ 77static 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. */ 89void 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} 99EXPORT_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 */ 105int 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 124invalidate: 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 134static 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 147int 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 166EXPORT_SYMBOL(set_blocksize); 167 168int 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 179EXPORT_SYMBOL(sb_set_blocksize); 180 181int 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 189EXPORT_SYMBOL(sb_min_blocksize); 190 191int sync_blockdev_nowait(struct block_device *bdev) 192{ 193 if (!bdev) 194 return 0; 195 return filemap_flush(bdev->bd_inode->i_mapping); 196} 197EXPORT_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 */ 203int 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} 209EXPORT_SYMBOL(sync_blockdev); 210 211int 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} 216EXPORT_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 */ 232int 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} 258EXPORT_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 */ 268int 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); 296out: 297 mutex_unlock(&bdev->bd_fsfreeze_mutex); 298 return error; 299} 300EXPORT_SYMBOL(bdev_thaw); 301 302/* 303 * pseudo-fs 304 */ 305 306static __cacheline_aligned_in_smp DEFINE_MUTEX(bdev_lock); 307static struct kmem_cache *bdev_cachep __ro_after_init; 308 309static 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 319static 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 338static void init_once(void *data) 339{ 340 struct bdev_inode *ei = data; 341 342 inode_init_once(&ei->vfs_inode); 343} 344 345static 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 352static 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 360static 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 370static 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 376struct super_block *blockdev_superblock __ro_after_init; 377struct vfsmount *blockdev_mnt __ro_after_init; 378EXPORT_SYMBOL_GPL(blockdev_superblock); 379 380void __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 397struct 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 430void 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 438void 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 448long 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 */ 472static 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 */ 514int 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; 521retry: 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} 546EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */ 547 548static 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 */ 566static 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} 587 588/** 589 * bd_abort_claiming - abort claiming of a block device 590 * @bdev: block device of interest 591 * @holder: holder that has claimed @bdev 592 * 593 * Abort claiming of a block device when the exclusive open failed. This can be 594 * also used when exclusive open is not actually desired and we just needed 595 * to block other exclusive openers for a while. 596 */ 597void bd_abort_claiming(struct block_device *bdev, void *holder) 598{ 599 mutex_lock(&bdev_lock); 600 bd_clear_claiming(bdev_whole(bdev), holder); 601 mutex_unlock(&bdev_lock); 602} 603EXPORT_SYMBOL(bd_abort_claiming); 604 605static void bd_end_claim(struct block_device *bdev, void *holder) 606{ 607 struct block_device *whole = bdev_whole(bdev); 608 bool unblock = false; 609 610 /* 611 * Release a claim on the device. The holder fields are protected with 612 * bdev_lock. open_mutex is used to synchronize disk_holder unlinking. 613 */ 614 mutex_lock(&bdev_lock); 615 WARN_ON_ONCE(bdev->bd_holder != holder); 616 WARN_ON_ONCE(--bdev->bd_holders < 0); 617 WARN_ON_ONCE(--whole->bd_holders < 0); 618 if (!bdev->bd_holders) { 619 mutex_lock(&bdev->bd_holder_lock); 620 bdev->bd_holder = NULL; 621 bdev->bd_holder_ops = NULL; 622 mutex_unlock(&bdev->bd_holder_lock); 623 if (bdev->bd_write_holder) 624 unblock = true; 625 } 626 if (!whole->bd_holders) 627 whole->bd_holder = NULL; 628 mutex_unlock(&bdev_lock); 629 630 /* 631 * If this was the last claim, remove holder link and unblock evpoll if 632 * it was a write holder. 633 */ 634 if (unblock) { 635 disk_unblock_events(bdev->bd_disk); 636 bdev->bd_write_holder = false; 637 } 638} 639 640static void blkdev_flush_mapping(struct block_device *bdev) 641{ 642 WARN_ON_ONCE(bdev->bd_holders); 643 sync_blockdev(bdev); 644 kill_bdev(bdev); 645 bdev_write_inode(bdev); 646} 647 648static void blkdev_put_whole(struct block_device *bdev) 649{ 650 if (atomic_dec_and_test(&bdev->bd_openers)) 651 blkdev_flush_mapping(bdev); 652 if (bdev->bd_disk->fops->release) 653 bdev->bd_disk->fops->release(bdev->bd_disk); 654} 655 656static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode) 657{ 658 struct gendisk *disk = bdev->bd_disk; 659 int ret; 660 661 if (disk->fops->open) { 662 ret = disk->fops->open(disk, mode); 663 if (ret) { 664 /* avoid ghost partitions on a removed medium */ 665 if (ret == -ENOMEDIUM && 666 test_bit(GD_NEED_PART_SCAN, &disk->state)) 667 bdev_disk_changed(disk, true); 668 return ret; 669 } 670 } 671 672 if (!atomic_read(&bdev->bd_openers)) 673 set_init_blocksize(bdev); 674 atomic_inc(&bdev->bd_openers); 675 if (test_bit(GD_NEED_PART_SCAN, &disk->state)) { 676 /* 677 * Only return scanning errors if we are called from contexts 678 * that explicitly want them, e.g. the BLKRRPART ioctl. 679 */ 680 ret = bdev_disk_changed(disk, false); 681 if (ret && (mode & BLK_OPEN_STRICT_SCAN)) { 682 blkdev_put_whole(bdev); 683 return ret; 684 } 685 } 686 return 0; 687} 688 689static int blkdev_get_part(struct block_device *part, blk_mode_t mode) 690{ 691 struct gendisk *disk = part->bd_disk; 692 int ret; 693 694 ret = blkdev_get_whole(bdev_whole(part), mode); 695 if (ret) 696 return ret; 697 698 ret = -ENXIO; 699 if (!bdev_nr_sectors(part)) 700 goto out_blkdev_put; 701 702 if (!atomic_read(&part->bd_openers)) { 703 disk->open_partitions++; 704 set_init_blocksize(part); 705 } 706 atomic_inc(&part->bd_openers); 707 return 0; 708 709out_blkdev_put: 710 blkdev_put_whole(bdev_whole(part)); 711 return ret; 712} 713 714int bdev_permission(dev_t dev, blk_mode_t mode, void *holder) 715{ 716 int ret; 717 718 ret = devcgroup_check_permission(DEVCG_DEV_BLOCK, 719 MAJOR(dev), MINOR(dev), 720 ((mode & BLK_OPEN_READ) ? DEVCG_ACC_READ : 0) | 721 ((mode & BLK_OPEN_WRITE) ? DEVCG_ACC_WRITE : 0)); 722 if (ret) 723 return ret; 724 725 /* Blocking writes requires exclusive opener */ 726 if (mode & BLK_OPEN_RESTRICT_WRITES && !holder) 727 return -EINVAL; 728 729 /* 730 * We're using error pointers to indicate to ->release() when we 731 * failed to open that block device. Also this doesn't make sense. 732 */ 733 if (WARN_ON_ONCE(IS_ERR(holder))) 734 return -EINVAL; 735 736 return 0; 737} 738 739static void blkdev_put_part(struct block_device *part) 740{ 741 struct block_device *whole = bdev_whole(part); 742 743 if (atomic_dec_and_test(&part->bd_openers)) { 744 blkdev_flush_mapping(part); 745 whole->bd_disk->open_partitions--; 746 } 747 blkdev_put_whole(whole); 748} 749 750struct block_device *blkdev_get_no_open(dev_t dev) 751{ 752 struct block_device *bdev; 753 struct inode *inode; 754 755 inode = ilookup(blockdev_superblock, dev); 756 if (!inode && IS_ENABLED(CONFIG_BLOCK_LEGACY_AUTOLOAD)) { 757 blk_request_module(dev); 758 inode = ilookup(blockdev_superblock, dev); 759 if (inode) 760 pr_warn_ratelimited( 761"block device autoloading is deprecated and will be removed.\n"); 762 } 763 if (!inode) 764 return NULL; 765 766 /* switch from the inode reference to a device mode one: */ 767 bdev = &BDEV_I(inode)->bdev; 768 if (!kobject_get_unless_zero(&bdev->bd_device.kobj)) 769 bdev = NULL; 770 iput(inode); 771 return bdev; 772} 773 774void blkdev_put_no_open(struct block_device *bdev) 775{ 776 put_device(&bdev->bd_device); 777} 778 779static bool bdev_writes_blocked(struct block_device *bdev) 780{ 781 return bdev->bd_writers < 0; 782} 783 784static void bdev_block_writes(struct block_device *bdev) 785{ 786 bdev->bd_writers--; 787} 788 789static void bdev_unblock_writes(struct block_device *bdev) 790{ 791 bdev->bd_writers++; 792} 793 794static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode) 795{ 796 if (bdev_allow_write_mounted) 797 return true; 798 /* Writes blocked? */ 799 if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev)) 800 return false; 801 if (mode & BLK_OPEN_RESTRICT_WRITES && bdev->bd_writers > 0) 802 return false; 803 return true; 804} 805 806static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode) 807{ 808 if (bdev_allow_write_mounted) 809 return; 810 811 /* Claim exclusive or shared write access. */ 812 if (mode & BLK_OPEN_RESTRICT_WRITES) 813 bdev_block_writes(bdev); 814 else if (mode & BLK_OPEN_WRITE) 815 bdev->bd_writers++; 816} 817 818static inline bool bdev_unclaimed(const struct file *bdev_file) 819{ 820 return bdev_file->private_data == BDEV_I(bdev_file->f_mapping->host); 821} 822 823static void bdev_yield_write_access(struct file *bdev_file) 824{ 825 struct block_device *bdev; 826 827 if (bdev_allow_write_mounted) 828 return; 829 830 if (bdev_unclaimed(bdev_file)) 831 return; 832 833 bdev = file_bdev(bdev_file); 834 835 if (bdev_file->f_mode & FMODE_WRITE_RESTRICTED) 836 bdev_unblock_writes(bdev); 837 else if (bdev_file->f_mode & FMODE_WRITE) 838 bdev->bd_writers--; 839} 840 841/** 842 * bdev_open - open a block device 843 * @bdev: block device to open 844 * @mode: open mode (BLK_OPEN_*) 845 * @holder: exclusive holder identifier 846 * @hops: holder operations 847 * @bdev_file: file for the block device 848 * 849 * Open the block device. If @holder is not %NULL, the block device is opened 850 * with exclusive access. Exclusive opens may nest for the same @holder. 851 * 852 * CONTEXT: 853 * Might sleep. 854 * 855 * RETURNS: 856 * zero on success, -errno on failure. 857 */ 858int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder, 859 const struct blk_holder_ops *hops, struct file *bdev_file) 860{ 861 bool unblock_events = true; 862 struct gendisk *disk = bdev->bd_disk; 863 int ret; 864 865 if (holder) { 866 mode |= BLK_OPEN_EXCL; 867 ret = bd_prepare_to_claim(bdev, holder, hops); 868 if (ret) 869 return ret; 870 } else { 871 if (WARN_ON_ONCE(mode & BLK_OPEN_EXCL)) 872 return -EIO; 873 } 874 875 disk_block_events(disk); 876 877 mutex_lock(&disk->open_mutex); 878 ret = -ENXIO; 879 if (!disk_live(disk)) 880 goto abort_claiming; 881 if (!try_module_get(disk->fops->owner)) 882 goto abort_claiming; 883 ret = -EBUSY; 884 if (!bdev_may_open(bdev, mode)) 885 goto abort_claiming; 886 if (bdev_is_partition(bdev)) 887 ret = blkdev_get_part(bdev, mode); 888 else 889 ret = blkdev_get_whole(bdev, mode); 890 if (ret) 891 goto put_module; 892 bdev_claim_write_access(bdev, mode); 893 if (holder) { 894 bd_finish_claiming(bdev, holder, hops); 895 896 /* 897 * Block event polling for write claims if requested. Any write 898 * holder makes the write_holder state stick until all are 899 * released. This is good enough and tracking individual 900 * writeable reference is too fragile given the way @mode is 901 * used in blkdev_get/put(). 902 */ 903 if ((mode & BLK_OPEN_WRITE) && !bdev->bd_write_holder && 904 (disk->event_flags & DISK_EVENT_FLAG_BLOCK_ON_EXCL_WRITE)) { 905 bdev->bd_write_holder = true; 906 unblock_events = false; 907 } 908 } 909 mutex_unlock(&disk->open_mutex); 910 911 if (unblock_events) 912 disk_unblock_events(disk); 913 914 bdev_file->f_flags |= O_LARGEFILE; 915 bdev_file->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT; 916 if (bdev_nowait(bdev)) 917 bdev_file->f_mode |= FMODE_NOWAIT; 918 if (mode & BLK_OPEN_RESTRICT_WRITES) 919 bdev_file->f_mode |= FMODE_WRITE_RESTRICTED; 920 bdev_file->f_mapping = bdev->bd_inode->i_mapping; 921 bdev_file->f_wb_err = filemap_sample_wb_err(bdev_file->f_mapping); 922 bdev_file->private_data = holder; 923 924 return 0; 925put_module: 926 module_put(disk->fops->owner); 927abort_claiming: 928 if (holder) 929 bd_abort_claiming(bdev, holder); 930 mutex_unlock(&disk->open_mutex); 931 disk_unblock_events(disk); 932 return ret; 933} 934 935/* 936 * If BLK_OPEN_WRITE_IOCTL is set then this is a historical quirk 937 * associated with the floppy driver where it has allowed ioctls if the 938 * file was opened for writing, but does not allow reads or writes. 939 * Make sure that this quirk is reflected in @f_flags. 940 * 941 * It can also happen if a block device is opened as O_RDWR | O_WRONLY. 942 */ 943static unsigned blk_to_file_flags(blk_mode_t mode) 944{ 945 unsigned int flags = 0; 946 947 if ((mode & (BLK_OPEN_READ | BLK_OPEN_WRITE)) == 948 (BLK_OPEN_READ | BLK_OPEN_WRITE)) 949 flags |= O_RDWR; 950 else if (mode & BLK_OPEN_WRITE_IOCTL) 951 flags |= O_RDWR | O_WRONLY; 952 else if (mode & BLK_OPEN_WRITE) 953 flags |= O_WRONLY; 954 else if (mode & BLK_OPEN_READ) 955 flags |= O_RDONLY; /* homeopathic, because O_RDONLY is 0 */ 956 else 957 WARN_ON_ONCE(true); 958 959 if (mode & BLK_OPEN_NDELAY) 960 flags |= O_NDELAY; 961 962 return flags; 963} 964 965struct file *bdev_file_open_by_dev(dev_t dev, blk_mode_t mode, void *holder, 966 const struct blk_holder_ops *hops) 967{ 968 struct file *bdev_file; 969 struct block_device *bdev; 970 unsigned int flags; 971 int ret; 972 973 ret = bdev_permission(dev, mode, holder); 974 if (ret) 975 return ERR_PTR(ret); 976 977 bdev = blkdev_get_no_open(dev); 978 if (!bdev) 979 return ERR_PTR(-ENXIO); 980 981 flags = blk_to_file_flags(mode); 982 bdev_file = alloc_file_pseudo_noaccount(bdev->bd_inode, 983 blockdev_mnt, "", flags | O_LARGEFILE, &def_blk_fops); 984 if (IS_ERR(bdev_file)) { 985 blkdev_put_no_open(bdev); 986 return bdev_file; 987 } 988 ihold(bdev->bd_inode); 989 990 ret = bdev_open(bdev, mode, holder, hops, bdev_file); 991 if (ret) { 992 /* We failed to open the block device. Let ->release() know. */ 993 bdev_file->private_data = ERR_PTR(ret); 994 fput(bdev_file); 995 return ERR_PTR(ret); 996 } 997 return bdev_file; 998} 999EXPORT_SYMBOL(bdev_file_open_by_dev); 1000 1001struct file *bdev_file_open_by_path(const char *path, blk_mode_t mode, 1002 void *holder, 1003 const struct blk_holder_ops *hops) 1004{ 1005 struct file *file; 1006 dev_t dev; 1007 int error; 1008 1009 error = lookup_bdev(path, &dev); 1010 if (error) 1011 return ERR_PTR(error); 1012 1013 file = bdev_file_open_by_dev(dev, mode, holder, hops); 1014 if (!IS_ERR(file) && (mode & BLK_OPEN_WRITE)) { 1015 if (bdev_read_only(file_bdev(file))) { 1016 fput(file); 1017 file = ERR_PTR(-EACCES); 1018 } 1019 } 1020 1021 return file; 1022} 1023EXPORT_SYMBOL(bdev_file_open_by_path); 1024 1025static inline void bd_yield_claim(struct file *bdev_file) 1026{ 1027 struct block_device *bdev = file_bdev(bdev_file); 1028 void *holder = bdev_file->private_data; 1029 1030 lockdep_assert_held(&bdev->bd_disk->open_mutex); 1031 1032 if (WARN_ON_ONCE(IS_ERR_OR_NULL(holder))) 1033 return; 1034 1035 if (!bdev_unclaimed(bdev_file)) 1036 bd_end_claim(bdev, holder); 1037} 1038 1039void bdev_release(struct file *bdev_file) 1040{ 1041 struct block_device *bdev = file_bdev(bdev_file); 1042 void *holder = bdev_file->private_data; 1043 struct gendisk *disk = bdev->bd_disk; 1044 1045 /* We failed to open that block device. */ 1046 if (IS_ERR(holder)) 1047 goto put_no_open; 1048 1049 /* 1050 * Sync early if it looks like we're the last one. If someone else 1051 * opens the block device between now and the decrement of bd_openers 1052 * then we did a sync that we didn't need to, but that's not the end 1053 * of the world and we want to avoid long (could be several minute) 1054 * syncs while holding the mutex. 1055 */ 1056 if (atomic_read(&bdev->bd_openers) == 1) 1057 sync_blockdev(bdev); 1058 1059 mutex_lock(&disk->open_mutex); 1060 bdev_yield_write_access(bdev_file); 1061 1062 if (holder) 1063 bd_yield_claim(bdev_file); 1064 1065 /* 1066 * Trigger event checking and tell drivers to flush MEDIA_CHANGE 1067 * event. This is to ensure detection of media removal commanded 1068 * from userland - e.g. eject(1). 1069 */ 1070 disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE); 1071 1072 if (bdev_is_partition(bdev)) 1073 blkdev_put_part(bdev); 1074 else 1075 blkdev_put_whole(bdev); 1076 mutex_unlock(&disk->open_mutex); 1077 1078 module_put(disk->fops->owner); 1079put_no_open: 1080 blkdev_put_no_open(bdev); 1081} 1082 1083/** 1084 * bdev_fput - yield claim to the block device and put the file 1085 * @bdev_file: open block device 1086 * 1087 * Yield claim on the block device and put the file. Ensure that the 1088 * block device can be reclaimed before the file is closed which is a 1089 * deferred operation. 1090 */ 1091void bdev_fput(struct file *bdev_file) 1092{ 1093 if (WARN_ON_ONCE(bdev_file->f_op != &def_blk_fops)) 1094 return; 1095 1096 if (bdev_file->private_data) { 1097 struct block_device *bdev = file_bdev(bdev_file); 1098 struct gendisk *disk = bdev->bd_disk; 1099 1100 mutex_lock(&disk->open_mutex); 1101 bdev_yield_write_access(bdev_file); 1102 bd_yield_claim(bdev_file); 1103 /* 1104 * Tell release we already gave up our hold on the 1105 * device and if write restrictions are available that 1106 * we already gave up write access to the device. 1107 */ 1108 bdev_file->private_data = BDEV_I(bdev_file->f_mapping->host); 1109 mutex_unlock(&disk->open_mutex); 1110 } 1111 1112 fput(bdev_file); 1113} 1114EXPORT_SYMBOL(bdev_fput); 1115 1116/** 1117 * lookup_bdev() - Look up a struct block_device by name. 1118 * @pathname: Name of the block device in the filesystem. 1119 * @dev: Pointer to the block device's dev_t, if found. 1120 * 1121 * Lookup the block device's dev_t at @pathname in the current 1122 * namespace if possible and return it in @dev. 1123 * 1124 * Context: May sleep. 1125 * Return: 0 if succeeded, negative errno otherwise. 1126 */ 1127int lookup_bdev(const char *pathname, dev_t *dev) 1128{ 1129 struct inode *inode; 1130 struct path path; 1131 int error; 1132 1133 if (!pathname || !*pathname) 1134 return -EINVAL; 1135 1136 error = kern_path(pathname, LOOKUP_FOLLOW, &path); 1137 if (error) 1138 return error; 1139 1140 inode = d_backing_inode(path.dentry); 1141 error = -ENOTBLK; 1142 if (!S_ISBLK(inode->i_mode)) 1143 goto out_path_put; 1144 error = -EACCES; 1145 if (!may_open_dev(&path)) 1146 goto out_path_put; 1147 1148 *dev = inode->i_rdev; 1149 error = 0; 1150out_path_put: 1151 path_put(&path); 1152 return error; 1153} 1154EXPORT_SYMBOL(lookup_bdev); 1155 1156/** 1157 * bdev_mark_dead - mark a block device as dead 1158 * @bdev: block device to operate on 1159 * @surprise: indicate a surprise removal 1160 * 1161 * Tell the file system that this devices or media is dead. If @surprise is set 1162 * to %true the device or media is already gone, if not we are preparing for an 1163 * orderly removal. 1164 * 1165 * This calls into the file system, which then typicall syncs out all dirty data 1166 * and writes back inodes and then invalidates any cached data in the inodes on 1167 * the file system. In addition we also invalidate the block device mapping. 1168 */ 1169void bdev_mark_dead(struct block_device *bdev, bool surprise) 1170{ 1171 mutex_lock(&bdev->bd_holder_lock); 1172 if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead) 1173 bdev->bd_holder_ops->mark_dead(bdev, surprise); 1174 else { 1175 mutex_unlock(&bdev->bd_holder_lock); 1176 sync_blockdev(bdev); 1177 } 1178 1179 invalidate_bdev(bdev); 1180} 1181/* 1182 * New drivers should not use this directly. There are some drivers however 1183 * that needs this for historical reasons. For example, the DASD driver has 1184 * historically had a shutdown to offline mode that doesn't actually remove the 1185 * gendisk that otherwise looks a lot like a safe device removal. 1186 */ 1187EXPORT_SYMBOL_GPL(bdev_mark_dead); 1188 1189void sync_bdevs(bool wait) 1190{ 1191 struct inode *inode, *old_inode = NULL; 1192 1193 spin_lock(&blockdev_superblock->s_inode_list_lock); 1194 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) { 1195 struct address_space *mapping = inode->i_mapping; 1196 struct block_device *bdev; 1197 1198 spin_lock(&inode->i_lock); 1199 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) || 1200 mapping->nrpages == 0) { 1201 spin_unlock(&inode->i_lock); 1202 continue; 1203 } 1204 __iget(inode); 1205 spin_unlock(&inode->i_lock); 1206 spin_unlock(&blockdev_superblock->s_inode_list_lock); 1207 /* 1208 * We hold a reference to 'inode' so it couldn't have been 1209 * removed from s_inodes list while we dropped the 1210 * s_inode_list_lock We cannot iput the inode now as we can 1211 * be holding the last reference and we cannot iput it under 1212 * s_inode_list_lock. So we keep the reference and iput it 1213 * later. 1214 */ 1215 iput(old_inode); 1216 old_inode = inode; 1217 bdev = I_BDEV(inode); 1218 1219 mutex_lock(&bdev->bd_disk->open_mutex); 1220 if (!atomic_read(&bdev->bd_openers)) { 1221 ; /* skip */ 1222 } else if (wait) { 1223 /* 1224 * We keep the error status of individual mapping so 1225 * that applications can catch the writeback error using 1226 * fsync(2). See filemap_fdatawait_keep_errors() for 1227 * details. 1228 */ 1229 filemap_fdatawait_keep_errors(inode->i_mapping); 1230 } else { 1231 filemap_fdatawrite(inode->i_mapping); 1232 } 1233 mutex_unlock(&bdev->bd_disk->open_mutex); 1234 1235 spin_lock(&blockdev_superblock->s_inode_list_lock); 1236 } 1237 spin_unlock(&blockdev_superblock->s_inode_list_lock); 1238 iput(old_inode); 1239} 1240 1241/* 1242 * Handle STATX_DIOALIGN for block devices. 1243 * 1244 * Note that the inode passed to this is the inode of a block device node file, 1245 * not the block device's internal inode. Therefore it is *not* valid to use 1246 * I_BDEV() here; the block device has to be looked up by i_rdev instead. 1247 */ 1248void bdev_statx_dioalign(struct inode *inode, struct kstat *stat) 1249{ 1250 struct block_device *bdev; 1251 1252 bdev = blkdev_get_no_open(inode->i_rdev); 1253 if (!bdev) 1254 return; 1255 1256 stat->dio_mem_align = bdev_dma_alignment(bdev) + 1; 1257 stat->dio_offset_align = bdev_logical_block_size(bdev); 1258 stat->result_mask |= STATX_DIOALIGN; 1259 1260 blkdev_put_no_open(bdev); 1261} 1262 1263static int __init setup_bdev_allow_write_mounted(char *str) 1264{ 1265 if (kstrtobool(str, &bdev_allow_write_mounted)) 1266 pr_warn("Invalid option string for bdev_allow_write_mounted:" 1267 " '%s'\n", str); 1268 return 1; 1269} 1270__setup("bdev_allow_write_mounted=", setup_bdev_allow_write_mounted); 1271