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