1/* 2 * linux/fs/block_dev.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE 6 */ 7 8#include <linux/init.h> 9#include <linux/mm.h> 10#include <linux/fcntl.h> 11#include <linux/slab.h> 12#include <linux/kmod.h> 13#include <linux/major.h> 14#include <linux/device_cgroup.h> 15#include <linux/highmem.h> 16#include <linux/blkdev.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/pagevec.h> 23#include <linux/writeback.h> 24#include <linux/mpage.h> 25#include <linux/mount.h> 26#include <linux/uio.h> 27#include <linux/namei.h> 28#include <linux/log2.h> 29#include <linux/cleancache.h> 30#include <asm/uaccess.h> 31#include "internal.h" 32 33struct bdev_inode { 34 struct block_device bdev; 35 struct inode vfs_inode; 36}; 37 38static const struct address_space_operations def_blk_aops; 39 40static inline struct bdev_inode *BDEV_I(struct inode *inode) 41{ 42 return container_of(inode, struct bdev_inode, vfs_inode); 43} 44 45inline struct block_device *I_BDEV(struct inode *inode) 46{ 47 return &BDEV_I(inode)->bdev; 48} 49EXPORT_SYMBOL(I_BDEV); 50 51static void bdev_write_inode(struct inode *inode) 52{ 53 spin_lock(&inode->i_lock); 54 while (inode->i_state & I_DIRTY) { 55 spin_unlock(&inode->i_lock); 56 WARN_ON_ONCE(write_inode_now(inode, true)); 57 spin_lock(&inode->i_lock); 58 } 59 spin_unlock(&inode->i_lock); 60} 61 62/* Kill _all_ buffers and pagecache , dirty or not.. */ 63void kill_bdev(struct block_device *bdev) 64{ 65 struct address_space *mapping = bdev->bd_inode->i_mapping; 66 67 if (mapping->nrpages == 0 && mapping->nrshadows == 0) 68 return; 69 70 invalidate_bh_lrus(); 71 truncate_inode_pages(mapping, 0); 72} 73EXPORT_SYMBOL(kill_bdev); 74 75/* Invalidate clean unused buffers and pagecache. */ 76void invalidate_bdev(struct block_device *bdev) 77{ 78 struct address_space *mapping = bdev->bd_inode->i_mapping; 79 80 if (mapping->nrpages == 0) 81 return; 82 83 invalidate_bh_lrus(); 84 lru_add_drain_all(); /* make sure all lru add caches are flushed */ 85 invalidate_mapping_pages(mapping, 0, -1); 86 /* 99% of the time, we don't need to flush the cleancache on the bdev. 87 * But, for the strange corners, lets be cautious 88 */ 89 cleancache_invalidate_inode(mapping); 90} 91EXPORT_SYMBOL(invalidate_bdev); 92 93int set_blocksize(struct block_device *bdev, int size) 94{ 95 /* Size must be a power of two, and between 512 and PAGE_SIZE */ 96 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size)) 97 return -EINVAL; 98 99 /* Size cannot be smaller than the size supported by the device */ 100 if (size < bdev_logical_block_size(bdev)) 101 return -EINVAL; 102 103 /* Don't change the size if it is same as current */ 104 if (bdev->bd_block_size != size) { 105 sync_blockdev(bdev); 106 bdev->bd_block_size = size; 107 bdev->bd_inode->i_blkbits = blksize_bits(size); 108 kill_bdev(bdev); 109 } 110 return 0; 111} 112 113EXPORT_SYMBOL(set_blocksize); 114 115int sb_set_blocksize(struct super_block *sb, int size) 116{ 117 if (set_blocksize(sb->s_bdev, size)) 118 return 0; 119 /* If we get here, we know size is power of two 120 * and it's value is between 512 and PAGE_SIZE */ 121 sb->s_blocksize = size; 122 sb->s_blocksize_bits = blksize_bits(size); 123 return sb->s_blocksize; 124} 125 126EXPORT_SYMBOL(sb_set_blocksize); 127 128int sb_min_blocksize(struct super_block *sb, int size) 129{ 130 int minsize = bdev_logical_block_size(sb->s_bdev); 131 if (size < minsize) 132 size = minsize; 133 return sb_set_blocksize(sb, size); 134} 135 136EXPORT_SYMBOL(sb_min_blocksize); 137 138static int 139blkdev_get_block(struct inode *inode, sector_t iblock, 140 struct buffer_head *bh, int create) 141{ 142 bh->b_bdev = I_BDEV(inode); 143 bh->b_blocknr = iblock; 144 set_buffer_mapped(bh); 145 return 0; 146} 147 148static ssize_t 149blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset) 150{ 151 struct file *file = iocb->ki_filp; 152 struct inode *inode = file->f_mapping->host; 153 154 return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset, 155 blkdev_get_block, NULL, NULL, 156 DIO_SKIP_DIO_COUNT); 157} 158 159int __sync_blockdev(struct block_device *bdev, int wait) 160{ 161 if (!bdev) 162 return 0; 163 if (!wait) 164 return filemap_flush(bdev->bd_inode->i_mapping); 165 return filemap_write_and_wait(bdev->bd_inode->i_mapping); 166} 167 168/* 169 * Write out and wait upon all the dirty data associated with a block 170 * device via its mapping. Does not take the superblock lock. 171 */ 172int sync_blockdev(struct block_device *bdev) 173{ 174 return __sync_blockdev(bdev, 1); 175} 176EXPORT_SYMBOL(sync_blockdev); 177 178/* 179 * Write out and wait upon all dirty data associated with this 180 * device. Filesystem data as well as the underlying block 181 * device. Takes the superblock lock. 182 */ 183int fsync_bdev(struct block_device *bdev) 184{ 185 struct super_block *sb = get_super(bdev); 186 if (sb) { 187 int res = sync_filesystem(sb); 188 drop_super(sb); 189 return res; 190 } 191 return sync_blockdev(bdev); 192} 193EXPORT_SYMBOL(fsync_bdev); 194 195/** 196 * freeze_bdev -- lock a filesystem and force it into a consistent state 197 * @bdev: blockdevice to lock 198 * 199 * If a superblock is found on this device, we take the s_umount semaphore 200 * on it to make sure nobody unmounts until the snapshot creation is done. 201 * The reference counter (bd_fsfreeze_count) guarantees that only the last 202 * unfreeze process can unfreeze the frozen filesystem actually when multiple 203 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and 204 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze 205 * actually. 206 */ 207struct super_block *freeze_bdev(struct block_device *bdev) 208{ 209 struct super_block *sb; 210 int error = 0; 211 212 mutex_lock(&bdev->bd_fsfreeze_mutex); 213 if (++bdev->bd_fsfreeze_count > 1) { 214 /* 215 * We don't even need to grab a reference - the first call 216 * to freeze_bdev grab an active reference and only the last 217 * thaw_bdev drops it. 218 */ 219 sb = get_super(bdev); 220 drop_super(sb); 221 mutex_unlock(&bdev->bd_fsfreeze_mutex); 222 return sb; 223 } 224 225 sb = get_active_super(bdev); 226 if (!sb) 227 goto out; 228 if (sb->s_op->freeze_super) 229 error = sb->s_op->freeze_super(sb); 230 else 231 error = freeze_super(sb); 232 if (error) { 233 deactivate_super(sb); 234 bdev->bd_fsfreeze_count--; 235 mutex_unlock(&bdev->bd_fsfreeze_mutex); 236 return ERR_PTR(error); 237 } 238 deactivate_super(sb); 239 out: 240 sync_blockdev(bdev); 241 mutex_unlock(&bdev->bd_fsfreeze_mutex); 242 return sb; /* thaw_bdev releases s->s_umount */ 243} 244EXPORT_SYMBOL(freeze_bdev); 245 246/** 247 * thaw_bdev -- unlock filesystem 248 * @bdev: blockdevice to unlock 249 * @sb: associated superblock 250 * 251 * Unlocks the filesystem and marks it writeable again after freeze_bdev(). 252 */ 253int thaw_bdev(struct block_device *bdev, struct super_block *sb) 254{ 255 int error = -EINVAL; 256 257 mutex_lock(&bdev->bd_fsfreeze_mutex); 258 if (!bdev->bd_fsfreeze_count) 259 goto out; 260 261 error = 0; 262 if (--bdev->bd_fsfreeze_count > 0) 263 goto out; 264 265 if (!sb) 266 goto out; 267 268 if (sb->s_op->thaw_super) 269 error = sb->s_op->thaw_super(sb); 270 else 271 error = thaw_super(sb); 272 if (error) { 273 bdev->bd_fsfreeze_count++; 274 mutex_unlock(&bdev->bd_fsfreeze_mutex); 275 return error; 276 } 277out: 278 mutex_unlock(&bdev->bd_fsfreeze_mutex); 279 return 0; 280} 281EXPORT_SYMBOL(thaw_bdev); 282 283static int blkdev_writepage(struct page *page, struct writeback_control *wbc) 284{ 285 return block_write_full_page(page, blkdev_get_block, wbc); 286} 287 288static int blkdev_readpage(struct file * file, struct page * page) 289{ 290 return block_read_full_page(page, blkdev_get_block); 291} 292 293static int blkdev_readpages(struct file *file, struct address_space *mapping, 294 struct list_head *pages, unsigned nr_pages) 295{ 296 return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block); 297} 298 299static int blkdev_write_begin(struct file *file, struct address_space *mapping, 300 loff_t pos, unsigned len, unsigned flags, 301 struct page **pagep, void **fsdata) 302{ 303 return block_write_begin(mapping, pos, len, flags, pagep, 304 blkdev_get_block); 305} 306 307static int blkdev_write_end(struct file *file, struct address_space *mapping, 308 loff_t pos, unsigned len, unsigned copied, 309 struct page *page, void *fsdata) 310{ 311 int ret; 312 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata); 313 314 unlock_page(page); 315 page_cache_release(page); 316 317 return ret; 318} 319 320/* 321 * private llseek: 322 * for a block special file file_inode(file)->i_size is zero 323 * so we compute the size by hand (just as in block_read/write above) 324 */ 325static loff_t block_llseek(struct file *file, loff_t offset, int whence) 326{ 327 struct inode *bd_inode = file->f_mapping->host; 328 loff_t retval; 329 330 mutex_lock(&bd_inode->i_mutex); 331 retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode)); 332 mutex_unlock(&bd_inode->i_mutex); 333 return retval; 334} 335 336int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) 337{ 338 struct inode *bd_inode = filp->f_mapping->host; 339 struct block_device *bdev = I_BDEV(bd_inode); 340 int error; 341 342 error = filemap_write_and_wait_range(filp->f_mapping, start, end); 343 if (error) 344 return error; 345 346 /* 347 * There is no need to serialise calls to blkdev_issue_flush with 348 * i_mutex and doing so causes performance issues with concurrent 349 * O_SYNC writers to a block device. 350 */ 351 error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL); 352 if (error == -EOPNOTSUPP) 353 error = 0; 354 355 return error; 356} 357EXPORT_SYMBOL(blkdev_fsync); 358 359/** 360 * bdev_read_page() - Start reading a page from a block device 361 * @bdev: The device to read the page from 362 * @sector: The offset on the device to read the page to (need not be aligned) 363 * @page: The page to read 364 * 365 * On entry, the page should be locked. It will be unlocked when the page 366 * has been read. If the block driver implements rw_page synchronously, 367 * that will be true on exit from this function, but it need not be. 368 * 369 * Errors returned by this function are usually "soft", eg out of memory, or 370 * queue full; callers should try a different route to read this page rather 371 * than propagate an error back up the stack. 372 * 373 * Return: negative errno if an error occurs, 0 if submission was successful. 374 */ 375int bdev_read_page(struct block_device *bdev, sector_t sector, 376 struct page *page) 377{ 378 const struct block_device_operations *ops = bdev->bd_disk->fops; 379 if (!ops->rw_page) 380 return -EOPNOTSUPP; 381 return ops->rw_page(bdev, sector + get_start_sect(bdev), page, READ); 382} 383EXPORT_SYMBOL_GPL(bdev_read_page); 384 385/** 386 * bdev_write_page() - Start writing a page to a block device 387 * @bdev: The device to write the page to 388 * @sector: The offset on the device to write the page to (need not be aligned) 389 * @page: The page to write 390 * @wbc: The writeback_control for the write 391 * 392 * On entry, the page should be locked and not currently under writeback. 393 * On exit, if the write started successfully, the page will be unlocked and 394 * under writeback. If the write failed already (eg the driver failed to 395 * queue the page to the device), the page will still be locked. If the 396 * caller is a ->writepage implementation, it will need to unlock the page. 397 * 398 * Errors returned by this function are usually "soft", eg out of memory, or 399 * queue full; callers should try a different route to write this page rather 400 * than propagate an error back up the stack. 401 * 402 * Return: negative errno if an error occurs, 0 if submission was successful. 403 */ 404int bdev_write_page(struct block_device *bdev, sector_t sector, 405 struct page *page, struct writeback_control *wbc) 406{ 407 int result; 408 int rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE; 409 const struct block_device_operations *ops = bdev->bd_disk->fops; 410 if (!ops->rw_page) 411 return -EOPNOTSUPP; 412 set_page_writeback(page); 413 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, rw); 414 if (result) 415 end_page_writeback(page); 416 else 417 unlock_page(page); 418 return result; 419} 420EXPORT_SYMBOL_GPL(bdev_write_page); 421 422/** 423 * bdev_direct_access() - Get the address for directly-accessibly memory 424 * @bdev: The device containing the memory 425 * @sector: The offset within the device 426 * @addr: Where to put the address of the memory 427 * @pfn: The Page Frame Number for the memory 428 * @size: The number of bytes requested 429 * 430 * If a block device is made up of directly addressable memory, this function 431 * will tell the caller the PFN and the address of the memory. The address 432 * may be directly dereferenced within the kernel without the need to call 433 * ioremap(), kmap() or similar. The PFN is suitable for inserting into 434 * page tables. 435 * 436 * Return: negative errno if an error occurs, otherwise the number of bytes 437 * accessible at this address. 438 */ 439long bdev_direct_access(struct block_device *bdev, sector_t sector, 440 void **addr, unsigned long *pfn, long size) 441{ 442 long avail; 443 const struct block_device_operations *ops = bdev->bd_disk->fops; 444 445 if (size < 0) 446 return size; 447 if (!ops->direct_access) 448 return -EOPNOTSUPP; 449 if ((sector + DIV_ROUND_UP(size, 512)) > 450 part_nr_sects_read(bdev->bd_part)) 451 return -ERANGE; 452 sector += get_start_sect(bdev); 453 if (sector % (PAGE_SIZE / 512)) 454 return -EINVAL; 455 avail = ops->direct_access(bdev, sector, addr, pfn, size); 456 if (!avail) 457 return -ERANGE; 458 return min(avail, size); 459} 460EXPORT_SYMBOL_GPL(bdev_direct_access); 461 462/* 463 * pseudo-fs 464 */ 465 466static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock); 467static struct kmem_cache * bdev_cachep __read_mostly; 468 469static struct inode *bdev_alloc_inode(struct super_block *sb) 470{ 471 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL); 472 if (!ei) 473 return NULL; 474 return &ei->vfs_inode; 475} 476 477static void bdev_i_callback(struct rcu_head *head) 478{ 479 struct inode *inode = container_of(head, struct inode, i_rcu); 480 struct bdev_inode *bdi = BDEV_I(inode); 481 482 kmem_cache_free(bdev_cachep, bdi); 483} 484 485static void bdev_destroy_inode(struct inode *inode) 486{ 487 call_rcu(&inode->i_rcu, bdev_i_callback); 488} 489 490static void init_once(void *foo) 491{ 492 struct bdev_inode *ei = (struct bdev_inode *) foo; 493 struct block_device *bdev = &ei->bdev; 494 495 memset(bdev, 0, sizeof(*bdev)); 496 mutex_init(&bdev->bd_mutex); 497 INIT_LIST_HEAD(&bdev->bd_inodes); 498 INIT_LIST_HEAD(&bdev->bd_list); 499#ifdef CONFIG_SYSFS 500 INIT_LIST_HEAD(&bdev->bd_holder_disks); 501#endif 502 inode_init_once(&ei->vfs_inode); 503 /* Initialize mutex for freeze. */ 504 mutex_init(&bdev->bd_fsfreeze_mutex); 505} 506 507static inline void __bd_forget(struct inode *inode) 508{ 509 list_del_init(&inode->i_devices); 510 inode->i_bdev = NULL; 511 inode->i_mapping = &inode->i_data; 512} 513 514static void bdev_evict_inode(struct inode *inode) 515{ 516 struct block_device *bdev = &BDEV_I(inode)->bdev; 517 struct list_head *p; 518 truncate_inode_pages_final(&inode->i_data); 519 invalidate_inode_buffers(inode); /* is it needed here? */ 520 clear_inode(inode); 521 spin_lock(&bdev_lock); 522 while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) { 523 __bd_forget(list_entry(p, struct inode, i_devices)); 524 } 525 list_del_init(&bdev->bd_list); 526 spin_unlock(&bdev_lock); 527} 528 529static const struct super_operations bdev_sops = { 530 .statfs = simple_statfs, 531 .alloc_inode = bdev_alloc_inode, 532 .destroy_inode = bdev_destroy_inode, 533 .drop_inode = generic_delete_inode, 534 .evict_inode = bdev_evict_inode, 535}; 536 537static struct dentry *bd_mount(struct file_system_type *fs_type, 538 int flags, const char *dev_name, void *data) 539{ 540 return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC); 541} 542 543static struct file_system_type bd_type = { 544 .name = "bdev", 545 .mount = bd_mount, 546 .kill_sb = kill_anon_super, 547}; 548 549static struct super_block *blockdev_superblock __read_mostly; 550 551void __init bdev_cache_init(void) 552{ 553 int err; 554 static struct vfsmount *bd_mnt; 555 556 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode), 557 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| 558 SLAB_MEM_SPREAD|SLAB_PANIC), 559 init_once); 560 err = register_filesystem(&bd_type); 561 if (err) 562 panic("Cannot register bdev pseudo-fs"); 563 bd_mnt = kern_mount(&bd_type); 564 if (IS_ERR(bd_mnt)) 565 panic("Cannot create bdev pseudo-fs"); 566 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ 567} 568 569/* 570 * Most likely _very_ bad one - but then it's hardly critical for small 571 * /dev and can be fixed when somebody will need really large one. 572 * Keep in mind that it will be fed through icache hash function too. 573 */ 574static inline unsigned long hash(dev_t dev) 575{ 576 return MAJOR(dev)+MINOR(dev); 577} 578 579static int bdev_test(struct inode *inode, void *data) 580{ 581 return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data; 582} 583 584static int bdev_set(struct inode *inode, void *data) 585{ 586 BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data; 587 return 0; 588} 589 590static LIST_HEAD(all_bdevs); 591 592struct block_device *bdget(dev_t dev) 593{ 594 struct block_device *bdev; 595 struct inode *inode; 596 597 inode = iget5_locked(blockdev_superblock, hash(dev), 598 bdev_test, bdev_set, &dev); 599 600 if (!inode) 601 return NULL; 602 603 bdev = &BDEV_I(inode)->bdev; 604 605 if (inode->i_state & I_NEW) { 606 bdev->bd_contains = NULL; 607 bdev->bd_super = NULL; 608 bdev->bd_inode = inode; 609 bdev->bd_block_size = (1 << inode->i_blkbits); 610 bdev->bd_part_count = 0; 611 bdev->bd_invalidated = 0; 612 inode->i_mode = S_IFBLK; 613 inode->i_rdev = dev; 614 inode->i_bdev = bdev; 615 inode->i_data.a_ops = &def_blk_aops; 616 mapping_set_gfp_mask(&inode->i_data, GFP_USER); 617 spin_lock(&bdev_lock); 618 list_add(&bdev->bd_list, &all_bdevs); 619 spin_unlock(&bdev_lock); 620 unlock_new_inode(inode); 621 } 622 return bdev; 623} 624 625EXPORT_SYMBOL(bdget); 626 627/** 628 * bdgrab -- Grab a reference to an already referenced block device 629 * @bdev: Block device to grab a reference to. 630 */ 631struct block_device *bdgrab(struct block_device *bdev) 632{ 633 ihold(bdev->bd_inode); 634 return bdev; 635} 636EXPORT_SYMBOL(bdgrab); 637 638long nr_blockdev_pages(void) 639{ 640 struct block_device *bdev; 641 long ret = 0; 642 spin_lock(&bdev_lock); 643 list_for_each_entry(bdev, &all_bdevs, bd_list) { 644 ret += bdev->bd_inode->i_mapping->nrpages; 645 } 646 spin_unlock(&bdev_lock); 647 return ret; 648} 649 650void bdput(struct block_device *bdev) 651{ 652 iput(bdev->bd_inode); 653} 654 655EXPORT_SYMBOL(bdput); 656 657static struct block_device *bd_acquire(struct inode *inode) 658{ 659 struct block_device *bdev; 660 661 spin_lock(&bdev_lock); 662 bdev = inode->i_bdev; 663 if (bdev) { 664 ihold(bdev->bd_inode); 665 spin_unlock(&bdev_lock); 666 return bdev; 667 } 668 spin_unlock(&bdev_lock); 669 670 bdev = bdget(inode->i_rdev); 671 if (bdev) { 672 spin_lock(&bdev_lock); 673 if (!inode->i_bdev) { 674 /* 675 * We take an additional reference to bd_inode, 676 * and it's released in clear_inode() of inode. 677 * So, we can access it via ->i_mapping always 678 * without igrab(). 679 */ 680 ihold(bdev->bd_inode); 681 inode->i_bdev = bdev; 682 inode->i_mapping = bdev->bd_inode->i_mapping; 683 list_add(&inode->i_devices, &bdev->bd_inodes); 684 } 685 spin_unlock(&bdev_lock); 686 } 687 return bdev; 688} 689 690int sb_is_blkdev_sb(struct super_block *sb) 691{ 692 return sb == blockdev_superblock; 693} 694 695/* Call when you free inode */ 696 697void bd_forget(struct inode *inode) 698{ 699 struct block_device *bdev = NULL; 700 701 spin_lock(&bdev_lock); 702 if (!sb_is_blkdev_sb(inode->i_sb)) 703 bdev = inode->i_bdev; 704 __bd_forget(inode); 705 spin_unlock(&bdev_lock); 706 707 if (bdev) 708 iput(bdev->bd_inode); 709} 710 711/** 712 * bd_may_claim - test whether a block device can be claimed 713 * @bdev: block device of interest 714 * @whole: whole block device containing @bdev, may equal @bdev 715 * @holder: holder trying to claim @bdev 716 * 717 * Test whether @bdev can be claimed by @holder. 718 * 719 * CONTEXT: 720 * spin_lock(&bdev_lock). 721 * 722 * RETURNS: 723 * %true if @bdev can be claimed, %false otherwise. 724 */ 725static bool bd_may_claim(struct block_device *bdev, struct block_device *whole, 726 void *holder) 727{ 728 if (bdev->bd_holder == holder) 729 return true; /* already a holder */ 730 else if (bdev->bd_holder != NULL) 731 return false; /* held by someone else */ 732 else if (bdev->bd_contains == bdev) 733 return true; /* is a whole device which isn't held */ 734 735 else if (whole->bd_holder == bd_may_claim) 736 return true; /* is a partition of a device that is being partitioned */ 737 else if (whole->bd_holder != NULL) 738 return false; /* is a partition of a held device */ 739 else 740 return true; /* is a partition of an un-held device */ 741} 742 743/** 744 * bd_prepare_to_claim - prepare to claim a block device 745 * @bdev: block device of interest 746 * @whole: the whole device containing @bdev, may equal @bdev 747 * @holder: holder trying to claim @bdev 748 * 749 * Prepare to claim @bdev. This function fails if @bdev is already 750 * claimed by another holder and waits if another claiming is in 751 * progress. This function doesn't actually claim. On successful 752 * return, the caller has ownership of bd_claiming and bd_holder[s]. 753 * 754 * CONTEXT: 755 * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab 756 * it multiple times. 757 * 758 * RETURNS: 759 * 0 if @bdev can be claimed, -EBUSY otherwise. 760 */ 761static int bd_prepare_to_claim(struct block_device *bdev, 762 struct block_device *whole, void *holder) 763{ 764retry: 765 /* if someone else claimed, fail */ 766 if (!bd_may_claim(bdev, whole, holder)) 767 return -EBUSY; 768 769 /* if claiming is already in progress, wait for it to finish */ 770 if (whole->bd_claiming) { 771 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0); 772 DEFINE_WAIT(wait); 773 774 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); 775 spin_unlock(&bdev_lock); 776 schedule(); 777 finish_wait(wq, &wait); 778 spin_lock(&bdev_lock); 779 goto retry; 780 } 781 782 /* yay, all mine */ 783 return 0; 784} 785 786/** 787 * bd_start_claiming - start claiming a block device 788 * @bdev: block device of interest 789 * @holder: holder trying to claim @bdev 790 * 791 * @bdev is about to be opened exclusively. Check @bdev can be opened 792 * exclusively and mark that an exclusive open is in progress. Each 793 * successful call to this function must be matched with a call to 794 * either bd_finish_claiming() or bd_abort_claiming() (which do not 795 * fail). 796 * 797 * This function is used to gain exclusive access to the block device 798 * without actually causing other exclusive open attempts to fail. It 799 * should be used when the open sequence itself requires exclusive 800 * access but may subsequently fail. 801 * 802 * CONTEXT: 803 * Might sleep. 804 * 805 * RETURNS: 806 * Pointer to the block device containing @bdev on success, ERR_PTR() 807 * value on failure. 808 */ 809static struct block_device *bd_start_claiming(struct block_device *bdev, 810 void *holder) 811{ 812 struct gendisk *disk; 813 struct block_device *whole; 814 int partno, err; 815 816 might_sleep(); 817 818 /* 819 * @bdev might not have been initialized properly yet, look up 820 * and grab the outer block device the hard way. 821 */ 822 disk = get_gendisk(bdev->bd_dev, &partno); 823 if (!disk) 824 return ERR_PTR(-ENXIO); 825 826 /* 827 * Normally, @bdev should equal what's returned from bdget_disk() 828 * if partno is 0; however, some drivers (floppy) use multiple 829 * bdev's for the same physical device and @bdev may be one of the 830 * aliases. Keep @bdev if partno is 0. This means claimer 831 * tracking is broken for those devices but it has always been that 832 * way. 833 */ 834 if (partno) 835 whole = bdget_disk(disk, 0); 836 else 837 whole = bdgrab(bdev); 838 839 module_put(disk->fops->owner); 840 put_disk(disk); 841 if (!whole) 842 return ERR_PTR(-ENOMEM); 843 844 /* prepare to claim, if successful, mark claiming in progress */ 845 spin_lock(&bdev_lock); 846 847 err = bd_prepare_to_claim(bdev, whole, holder); 848 if (err == 0) { 849 whole->bd_claiming = holder; 850 spin_unlock(&bdev_lock); 851 return whole; 852 } else { 853 spin_unlock(&bdev_lock); 854 bdput(whole); 855 return ERR_PTR(err); 856 } 857} 858 859#ifdef CONFIG_SYSFS 860struct bd_holder_disk { 861 struct list_head list; 862 struct gendisk *disk; 863 int refcnt; 864}; 865 866static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev, 867 struct gendisk *disk) 868{ 869 struct bd_holder_disk *holder; 870 871 list_for_each_entry(holder, &bdev->bd_holder_disks, list) 872 if (holder->disk == disk) 873 return holder; 874 return NULL; 875} 876 877static int add_symlink(struct kobject *from, struct kobject *to) 878{ 879 return sysfs_create_link(from, to, kobject_name(to)); 880} 881 882static void del_symlink(struct kobject *from, struct kobject *to) 883{ 884 sysfs_remove_link(from, kobject_name(to)); 885} 886 887/** 888 * bd_link_disk_holder - create symlinks between holding disk and slave bdev 889 * @bdev: the claimed slave bdev 890 * @disk: the holding disk 891 * 892 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. 893 * 894 * This functions creates the following sysfs symlinks. 895 * 896 * - from "slaves" directory of the holder @disk to the claimed @bdev 897 * - from "holders" directory of the @bdev to the holder @disk 898 * 899 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is 900 * passed to bd_link_disk_holder(), then: 901 * 902 * /sys/block/dm-0/slaves/sda --> /sys/block/sda 903 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0 904 * 905 * The caller must have claimed @bdev before calling this function and 906 * ensure that both @bdev and @disk are valid during the creation and 907 * lifetime of these symlinks. 908 * 909 * CONTEXT: 910 * Might sleep. 911 * 912 * RETURNS: 913 * 0 on success, -errno on failure. 914 */ 915int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) 916{ 917 struct bd_holder_disk *holder; 918 int ret = 0; 919 920 mutex_lock(&bdev->bd_mutex); 921 922 WARN_ON_ONCE(!bdev->bd_holder); 923 924 /* FIXME: remove the following once add_disk() handles errors */ 925 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir)) 926 goto out_unlock; 927 928 holder = bd_find_holder_disk(bdev, disk); 929 if (holder) { 930 holder->refcnt++; 931 goto out_unlock; 932 } 933 934 holder = kzalloc(sizeof(*holder), GFP_KERNEL); 935 if (!holder) { 936 ret = -ENOMEM; 937 goto out_unlock; 938 } 939 940 INIT_LIST_HEAD(&holder->list); 941 holder->disk = disk; 942 holder->refcnt = 1; 943 944 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); 945 if (ret) 946 goto out_free; 947 948 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); 949 if (ret) 950 goto out_del; 951 /* 952 * bdev could be deleted beneath us which would implicitly destroy 953 * the holder directory. Hold on to it. 954 */ 955 kobject_get(bdev->bd_part->holder_dir); 956 957 list_add(&holder->list, &bdev->bd_holder_disks); 958 goto out_unlock; 959 960out_del: 961 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); 962out_free: 963 kfree(holder); 964out_unlock: 965 mutex_unlock(&bdev->bd_mutex); 966 return ret; 967} 968EXPORT_SYMBOL_GPL(bd_link_disk_holder); 969 970/** 971 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder() 972 * @bdev: the calimed slave bdev 973 * @disk: the holding disk 974 * 975 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. 976 * 977 * CONTEXT: 978 * Might sleep. 979 */ 980void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) 981{ 982 struct bd_holder_disk *holder; 983 984 mutex_lock(&bdev->bd_mutex); 985 986 holder = bd_find_holder_disk(bdev, disk); 987 988 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) { 989 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); 990 del_symlink(bdev->bd_part->holder_dir, 991 &disk_to_dev(disk)->kobj); 992 kobject_put(bdev->bd_part->holder_dir); 993 list_del_init(&holder->list); 994 kfree(holder); 995 } 996 997 mutex_unlock(&bdev->bd_mutex); 998} 999EXPORT_SYMBOL_GPL(bd_unlink_disk_holder); 1000#endif 1001 1002/** 1003 * flush_disk - invalidates all buffer-cache entries on a disk 1004 * 1005 * @bdev: struct block device to be flushed 1006 * @kill_dirty: flag to guide handling of dirty inodes 1007 * 1008 * Invalidates all buffer-cache entries on a disk. It should be called 1009 * when a disk has been changed -- either by a media change or online 1010 * resize. 1011 */ 1012static void flush_disk(struct block_device *bdev, bool kill_dirty) 1013{ 1014 if (__invalidate_device(bdev, kill_dirty)) { 1015 char name[BDEVNAME_SIZE] = ""; 1016 1017 if (bdev->bd_disk) 1018 disk_name(bdev->bd_disk, 0, name); 1019 printk(KERN_WARNING "VFS: busy inodes on changed media or " 1020 "resized disk %s\n", name); 1021 } 1022 1023 if (!bdev->bd_disk) 1024 return; 1025 if (disk_part_scan_enabled(bdev->bd_disk)) 1026 bdev->bd_invalidated = 1; 1027} 1028 1029/** 1030 * check_disk_size_change - checks for disk size change and adjusts bdev size. 1031 * @disk: struct gendisk to check 1032 * @bdev: struct bdev to adjust. 1033 * 1034 * This routine checks to see if the bdev size does not match the disk size 1035 * and adjusts it if it differs. 1036 */ 1037void check_disk_size_change(struct gendisk *disk, struct block_device *bdev) 1038{ 1039 loff_t disk_size, bdev_size; 1040 1041 disk_size = (loff_t)get_capacity(disk) << 9; 1042 bdev_size = i_size_read(bdev->bd_inode); 1043 if (disk_size != bdev_size) { 1044 char name[BDEVNAME_SIZE]; 1045 1046 disk_name(disk, 0, name); 1047 printk(KERN_INFO 1048 "%s: detected capacity change from %lld to %lld\n", 1049 name, bdev_size, disk_size); 1050 i_size_write(bdev->bd_inode, disk_size); 1051 flush_disk(bdev, false); 1052 } 1053} 1054EXPORT_SYMBOL(check_disk_size_change); 1055 1056/** 1057 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back 1058 * @disk: struct gendisk to be revalidated 1059 * 1060 * This routine is a wrapper for lower-level driver's revalidate_disk 1061 * call-backs. It is used to do common pre and post operations needed 1062 * for all revalidate_disk operations. 1063 */ 1064int revalidate_disk(struct gendisk *disk) 1065{ 1066 struct block_device *bdev; 1067 int ret = 0; 1068 1069 if (disk->fops->revalidate_disk) 1070 ret = disk->fops->revalidate_disk(disk); 1071 1072 bdev = bdget_disk(disk, 0); 1073 if (!bdev) 1074 return ret; 1075 1076 mutex_lock(&bdev->bd_mutex); 1077 check_disk_size_change(disk, bdev); 1078 bdev->bd_invalidated = 0; 1079 mutex_unlock(&bdev->bd_mutex); 1080 bdput(bdev); 1081 return ret; 1082} 1083EXPORT_SYMBOL(revalidate_disk); 1084 1085/* 1086 * This routine checks whether a removable media has been changed, 1087 * and invalidates all buffer-cache-entries in that case. This 1088 * is a relatively slow routine, so we have to try to minimize using 1089 * it. Thus it is called only upon a 'mount' or 'open'. This 1090 * is the best way of combining speed and utility, I think. 1091 * People changing diskettes in the middle of an operation deserve 1092 * to lose :-) 1093 */ 1094int check_disk_change(struct block_device *bdev) 1095{ 1096 struct gendisk *disk = bdev->bd_disk; 1097 const struct block_device_operations *bdops = disk->fops; 1098 unsigned int events; 1099 1100 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE | 1101 DISK_EVENT_EJECT_REQUEST); 1102 if (!(events & DISK_EVENT_MEDIA_CHANGE)) 1103 return 0; 1104 1105 flush_disk(bdev, true); 1106 if (bdops->revalidate_disk) 1107 bdops->revalidate_disk(bdev->bd_disk); 1108 return 1; 1109} 1110 1111EXPORT_SYMBOL(check_disk_change); 1112 1113void bd_set_size(struct block_device *bdev, loff_t size) 1114{ 1115 unsigned bsize = bdev_logical_block_size(bdev); 1116 1117 mutex_lock(&bdev->bd_inode->i_mutex); 1118 i_size_write(bdev->bd_inode, size); 1119 mutex_unlock(&bdev->bd_inode->i_mutex); 1120 while (bsize < PAGE_CACHE_SIZE) { 1121 if (size & bsize) 1122 break; 1123 bsize <<= 1; 1124 } 1125 bdev->bd_block_size = bsize; 1126 bdev->bd_inode->i_blkbits = blksize_bits(bsize); 1127} 1128EXPORT_SYMBOL(bd_set_size); 1129 1130static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part); 1131 1132/* 1133 * bd_mutex locking: 1134 * 1135 * mutex_lock(part->bd_mutex) 1136 * mutex_lock_nested(whole->bd_mutex, 1) 1137 */ 1138 1139static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) 1140{ 1141 struct gendisk *disk; 1142 struct module *owner; 1143 int ret; 1144 int partno; 1145 int perm = 0; 1146 1147 if (mode & FMODE_READ) 1148 perm |= MAY_READ; 1149 if (mode & FMODE_WRITE) 1150 perm |= MAY_WRITE; 1151 /* 1152 * hooks: /n/, see "layering violations". 1153 */ 1154 if (!for_part) { 1155 ret = devcgroup_inode_permission(bdev->bd_inode, perm); 1156 if (ret != 0) { 1157 bdput(bdev); 1158 return ret; 1159 } 1160 } 1161 1162 restart: 1163 1164 ret = -ENXIO; 1165 disk = get_gendisk(bdev->bd_dev, &partno); 1166 if (!disk) 1167 goto out; 1168 owner = disk->fops->owner; 1169 1170 disk_block_events(disk); 1171 mutex_lock_nested(&bdev->bd_mutex, for_part); 1172 if (!bdev->bd_openers) { 1173 bdev->bd_disk = disk; 1174 bdev->bd_queue = disk->queue; 1175 bdev->bd_contains = bdev; 1176 if (!partno) { 1177 ret = -ENXIO; 1178 bdev->bd_part = disk_get_part(disk, partno); 1179 if (!bdev->bd_part) 1180 goto out_clear; 1181 1182 ret = 0; 1183 if (disk->fops->open) { 1184 ret = disk->fops->open(bdev, mode); 1185 if (ret == -ERESTARTSYS) { 1186 /* Lost a race with 'disk' being 1187 * deleted, try again. 1188 * See md.c 1189 */ 1190 disk_put_part(bdev->bd_part); 1191 bdev->bd_part = NULL; 1192 bdev->bd_disk = NULL; 1193 bdev->bd_queue = NULL; 1194 mutex_unlock(&bdev->bd_mutex); 1195 disk_unblock_events(disk); 1196 put_disk(disk); 1197 module_put(owner); 1198 goto restart; 1199 } 1200 } 1201 1202 if (!ret) 1203 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9); 1204 1205 /* 1206 * If the device is invalidated, rescan partition 1207 * if open succeeded or failed with -ENOMEDIUM. 1208 * The latter is necessary to prevent ghost 1209 * partitions on a removed medium. 1210 */ 1211 if (bdev->bd_invalidated) { 1212 if (!ret) 1213 rescan_partitions(disk, bdev); 1214 else if (ret == -ENOMEDIUM) 1215 invalidate_partitions(disk, bdev); 1216 } 1217 if (ret) 1218 goto out_clear; 1219 } else { 1220 struct block_device *whole; 1221 whole = bdget_disk(disk, 0); 1222 ret = -ENOMEM; 1223 if (!whole) 1224 goto out_clear; 1225 BUG_ON(for_part); 1226 ret = __blkdev_get(whole, mode, 1); 1227 if (ret) 1228 goto out_clear; 1229 bdev->bd_contains = whole; 1230 bdev->bd_part = disk_get_part(disk, partno); 1231 if (!(disk->flags & GENHD_FL_UP) || 1232 !bdev->bd_part || !bdev->bd_part->nr_sects) { 1233 ret = -ENXIO; 1234 goto out_clear; 1235 } 1236 bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9); 1237 /* 1238 * If the partition is not aligned on a page 1239 * boundary, we can't do dax I/O to it. 1240 */ 1241 if ((bdev->bd_part->start_sect % (PAGE_SIZE / 512)) || 1242 (bdev->bd_part->nr_sects % (PAGE_SIZE / 512))) 1243 bdev->bd_inode->i_flags &= ~S_DAX; 1244 } 1245 } else { 1246 if (bdev->bd_contains == bdev) { 1247 ret = 0; 1248 if (bdev->bd_disk->fops->open) 1249 ret = bdev->bd_disk->fops->open(bdev, mode); 1250 /* the same as first opener case, read comment there */ 1251 if (bdev->bd_invalidated) { 1252 if (!ret) 1253 rescan_partitions(bdev->bd_disk, bdev); 1254 else if (ret == -ENOMEDIUM) 1255 invalidate_partitions(bdev->bd_disk, bdev); 1256 } 1257 if (ret) 1258 goto out_unlock_bdev; 1259 } 1260 /* only one opener holds refs to the module and disk */ 1261 put_disk(disk); 1262 module_put(owner); 1263 } 1264 bdev->bd_openers++; 1265 if (for_part) 1266 bdev->bd_part_count++; 1267 mutex_unlock(&bdev->bd_mutex); 1268 disk_unblock_events(disk); 1269 return 0; 1270 1271 out_clear: 1272 disk_put_part(bdev->bd_part); 1273 bdev->bd_disk = NULL; 1274 bdev->bd_part = NULL; 1275 bdev->bd_queue = NULL; 1276 if (bdev != bdev->bd_contains) 1277 __blkdev_put(bdev->bd_contains, mode, 1); 1278 bdev->bd_contains = NULL; 1279 out_unlock_bdev: 1280 mutex_unlock(&bdev->bd_mutex); 1281 disk_unblock_events(disk); 1282 put_disk(disk); 1283 module_put(owner); 1284 out: 1285 bdput(bdev); 1286 1287 return ret; 1288} 1289 1290/** 1291 * blkdev_get - open a block device 1292 * @bdev: block_device to open 1293 * @mode: FMODE_* mask 1294 * @holder: exclusive holder identifier 1295 * 1296 * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is 1297 * open with exclusive access. Specifying %FMODE_EXCL with %NULL 1298 * @holder is invalid. Exclusive opens may nest for the same @holder. 1299 * 1300 * On success, the reference count of @bdev is unchanged. On failure, 1301 * @bdev is put. 1302 * 1303 * CONTEXT: 1304 * Might sleep. 1305 * 1306 * RETURNS: 1307 * 0 on success, -errno on failure. 1308 */ 1309int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) 1310{ 1311 struct block_device *whole = NULL; 1312 int res; 1313 1314 WARN_ON_ONCE((mode & FMODE_EXCL) && !holder); 1315 1316 if ((mode & FMODE_EXCL) && holder) { 1317 whole = bd_start_claiming(bdev, holder); 1318 if (IS_ERR(whole)) { 1319 bdput(bdev); 1320 return PTR_ERR(whole); 1321 } 1322 } 1323 1324 res = __blkdev_get(bdev, mode, 0); 1325 1326 if (whole) { 1327 struct gendisk *disk = whole->bd_disk; 1328 1329 /* finish claiming */ 1330 mutex_lock(&bdev->bd_mutex); 1331 spin_lock(&bdev_lock); 1332 1333 if (!res) { 1334 BUG_ON(!bd_may_claim(bdev, whole, holder)); 1335 /* 1336 * Note that for a whole device bd_holders 1337 * will be incremented twice, and bd_holder 1338 * will be set to bd_may_claim before being 1339 * set to holder 1340 */ 1341 whole->bd_holders++; 1342 whole->bd_holder = bd_may_claim; 1343 bdev->bd_holders++; 1344 bdev->bd_holder = holder; 1345 } 1346 1347 /* tell others that we're done */ 1348 BUG_ON(whole->bd_claiming != holder); 1349 whole->bd_claiming = NULL; 1350 wake_up_bit(&whole->bd_claiming, 0); 1351 1352 spin_unlock(&bdev_lock); 1353 1354 /* 1355 * Block event polling for write claims if requested. Any 1356 * write holder makes the write_holder state stick until 1357 * all are released. This is good enough and tracking 1358 * individual writeable reference is too fragile given the 1359 * way @mode is used in blkdev_get/put(). 1360 */ 1361 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder && 1362 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { 1363 bdev->bd_write_holder = true; 1364 disk_block_events(disk); 1365 } 1366 1367 mutex_unlock(&bdev->bd_mutex); 1368 bdput(whole); 1369 } 1370 1371 return res; 1372} 1373EXPORT_SYMBOL(blkdev_get); 1374 1375/** 1376 * blkdev_get_by_path - open a block device by name 1377 * @path: path to the block device to open 1378 * @mode: FMODE_* mask 1379 * @holder: exclusive holder identifier 1380 * 1381 * Open the blockdevice described by the device file at @path. @mode 1382 * and @holder are identical to blkdev_get(). 1383 * 1384 * On success, the returned block_device has reference count of one. 1385 * 1386 * CONTEXT: 1387 * Might sleep. 1388 * 1389 * RETURNS: 1390 * Pointer to block_device on success, ERR_PTR(-errno) on failure. 1391 */ 1392struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, 1393 void *holder) 1394{ 1395 struct block_device *bdev; 1396 int err; 1397 1398 bdev = lookup_bdev(path); 1399 if (IS_ERR(bdev)) 1400 return bdev; 1401 1402 err = blkdev_get(bdev, mode, holder); 1403 if (err) 1404 return ERR_PTR(err); 1405 1406 if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) { 1407 blkdev_put(bdev, mode); 1408 return ERR_PTR(-EACCES); 1409 } 1410 1411 return bdev; 1412} 1413EXPORT_SYMBOL(blkdev_get_by_path); 1414 1415/** 1416 * blkdev_get_by_dev - open a block device by device number 1417 * @dev: device number of block device to open 1418 * @mode: FMODE_* mask 1419 * @holder: exclusive holder identifier 1420 * 1421 * Open the blockdevice described by device number @dev. @mode and 1422 * @holder are identical to blkdev_get(). 1423 * 1424 * Use it ONLY if you really do not have anything better - i.e. when 1425 * you are behind a truly sucky interface and all you are given is a 1426 * device number. _Never_ to be used for internal purposes. If you 1427 * ever need it - reconsider your API. 1428 * 1429 * On success, the returned block_device has reference count of one. 1430 * 1431 * CONTEXT: 1432 * Might sleep. 1433 * 1434 * RETURNS: 1435 * Pointer to block_device on success, ERR_PTR(-errno) on failure. 1436 */ 1437struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) 1438{ 1439 struct block_device *bdev; 1440 int err; 1441 1442 bdev = bdget(dev); 1443 if (!bdev) 1444 return ERR_PTR(-ENOMEM); 1445 1446 err = blkdev_get(bdev, mode, holder); 1447 if (err) 1448 return ERR_PTR(err); 1449 1450 return bdev; 1451} 1452EXPORT_SYMBOL(blkdev_get_by_dev); 1453 1454static int blkdev_open(struct inode * inode, struct file * filp) 1455{ 1456 struct block_device *bdev; 1457 1458 /* 1459 * Preserve backwards compatibility and allow large file access 1460 * even if userspace doesn't ask for it explicitly. Some mkfs 1461 * binary needs it. We might want to drop this workaround 1462 * during an unstable branch. 1463 */ 1464 filp->f_flags |= O_LARGEFILE; 1465 1466 if (filp->f_flags & O_NDELAY) 1467 filp->f_mode |= FMODE_NDELAY; 1468 if (filp->f_flags & O_EXCL) 1469 filp->f_mode |= FMODE_EXCL; 1470 if ((filp->f_flags & O_ACCMODE) == 3) 1471 filp->f_mode |= FMODE_WRITE_IOCTL; 1472 1473 bdev = bd_acquire(inode); 1474 if (bdev == NULL) 1475 return -ENOMEM; 1476 1477 filp->f_mapping = bdev->bd_inode->i_mapping; 1478 1479 return blkdev_get(bdev, filp->f_mode, filp); 1480} 1481 1482static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) 1483{ 1484 struct gendisk *disk = bdev->bd_disk; 1485 struct block_device *victim = NULL; 1486 1487 mutex_lock_nested(&bdev->bd_mutex, for_part); 1488 if (for_part) 1489 bdev->bd_part_count--; 1490 1491 if (!--bdev->bd_openers) { 1492 WARN_ON_ONCE(bdev->bd_holders); 1493 sync_blockdev(bdev); 1494 kill_bdev(bdev); 1495 /* 1496 * ->release can cause the queue to disappear, so flush all 1497 * dirty data before. 1498 */ 1499 bdev_write_inode(bdev->bd_inode); 1500 } 1501 if (bdev->bd_contains == bdev) { 1502 if (disk->fops->release) 1503 disk->fops->release(disk, mode); 1504 } 1505 if (!bdev->bd_openers) { 1506 struct module *owner = disk->fops->owner; 1507 1508 disk_put_part(bdev->bd_part); 1509 bdev->bd_part = NULL; 1510 bdev->bd_disk = NULL; 1511 if (bdev != bdev->bd_contains) 1512 victim = bdev->bd_contains; 1513 bdev->bd_contains = NULL; 1514 1515 put_disk(disk); 1516 module_put(owner); 1517 } 1518 mutex_unlock(&bdev->bd_mutex); 1519 bdput(bdev); 1520 if (victim) 1521 __blkdev_put(victim, mode, 1); 1522} 1523 1524void blkdev_put(struct block_device *bdev, fmode_t mode) 1525{ 1526 mutex_lock(&bdev->bd_mutex); 1527 1528 if (mode & FMODE_EXCL) { 1529 bool bdev_free; 1530 1531 /* 1532 * Release a claim on the device. The holder fields 1533 * are protected with bdev_lock. bd_mutex is to 1534 * synchronize disk_holder unlinking. 1535 */ 1536 spin_lock(&bdev_lock); 1537 1538 WARN_ON_ONCE(--bdev->bd_holders < 0); 1539 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0); 1540 1541 /* bd_contains might point to self, check in a separate step */ 1542 if ((bdev_free = !bdev->bd_holders)) 1543 bdev->bd_holder = NULL; 1544 if (!bdev->bd_contains->bd_holders) 1545 bdev->bd_contains->bd_holder = NULL; 1546 1547 spin_unlock(&bdev_lock); 1548 1549 /* 1550 * If this was the last claim, remove holder link and 1551 * unblock evpoll if it was a write holder. 1552 */ 1553 if (bdev_free && bdev->bd_write_holder) { 1554 disk_unblock_events(bdev->bd_disk); 1555 bdev->bd_write_holder = false; 1556 } 1557 } 1558 1559 /* 1560 * Trigger event checking and tell drivers to flush MEDIA_CHANGE 1561 * event. This is to ensure detection of media removal commanded 1562 * from userland - e.g. eject(1). 1563 */ 1564 disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE); 1565 1566 mutex_unlock(&bdev->bd_mutex); 1567 1568 __blkdev_put(bdev, mode, 0); 1569} 1570EXPORT_SYMBOL(blkdev_put); 1571 1572static int blkdev_close(struct inode * inode, struct file * filp) 1573{ 1574 struct block_device *bdev = I_BDEV(filp->f_mapping->host); 1575 blkdev_put(bdev, filp->f_mode); 1576 return 0; 1577} 1578 1579static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg) 1580{ 1581 struct block_device *bdev = I_BDEV(file->f_mapping->host); 1582 fmode_t mode = file->f_mode; 1583 1584 /* 1585 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have 1586 * to updated it before every ioctl. 1587 */ 1588 if (file->f_flags & O_NDELAY) 1589 mode |= FMODE_NDELAY; 1590 else 1591 mode &= ~FMODE_NDELAY; 1592 1593 return blkdev_ioctl(bdev, mode, cmd, arg); 1594} 1595 1596/* 1597 * Write data to the block device. Only intended for the block device itself 1598 * and the raw driver which basically is a fake block device. 1599 * 1600 * Does not take i_mutex for the write and thus is not for general purpose 1601 * use. 1602 */ 1603ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from) 1604{ 1605 struct file *file = iocb->ki_filp; 1606 struct inode *bd_inode = file->f_mapping->host; 1607 loff_t size = i_size_read(bd_inode); 1608 struct blk_plug plug; 1609 ssize_t ret; 1610 1611 if (bdev_read_only(I_BDEV(bd_inode))) 1612 return -EPERM; 1613 1614 if (!iov_iter_count(from)) 1615 return 0; 1616 1617 if (iocb->ki_pos >= size) 1618 return -ENOSPC; 1619 1620 iov_iter_truncate(from, size - iocb->ki_pos); 1621 1622 blk_start_plug(&plug); 1623 ret = __generic_file_write_iter(iocb, from); 1624 if (ret > 0) { 1625 ssize_t err; 1626 err = generic_write_sync(file, iocb->ki_pos - ret, ret); 1627 if (err < 0) 1628 ret = err; 1629 } 1630 blk_finish_plug(&plug); 1631 return ret; 1632} 1633EXPORT_SYMBOL_GPL(blkdev_write_iter); 1634 1635ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to) 1636{ 1637 struct file *file = iocb->ki_filp; 1638 struct inode *bd_inode = file->f_mapping->host; 1639 loff_t size = i_size_read(bd_inode); 1640 loff_t pos = iocb->ki_pos; 1641 1642 if (pos >= size) 1643 return 0; 1644 1645 size -= pos; 1646 iov_iter_truncate(to, size); 1647 return generic_file_read_iter(iocb, to); 1648} 1649EXPORT_SYMBOL_GPL(blkdev_read_iter); 1650 1651/* 1652 * Try to release a page associated with block device when the system 1653 * is under memory pressure. 1654 */ 1655static int blkdev_releasepage(struct page *page, gfp_t wait) 1656{ 1657 struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super; 1658 1659 if (super && super->s_op->bdev_try_to_free_page) 1660 return super->s_op->bdev_try_to_free_page(super, page, wait); 1661 1662 return try_to_free_buffers(page); 1663} 1664 1665static const struct address_space_operations def_blk_aops = { 1666 .readpage = blkdev_readpage, 1667 .readpages = blkdev_readpages, 1668 .writepage = blkdev_writepage, 1669 .write_begin = blkdev_write_begin, 1670 .write_end = blkdev_write_end, 1671 .writepages = generic_writepages, 1672 .releasepage = blkdev_releasepage, 1673 .direct_IO = blkdev_direct_IO, 1674 .is_dirty_writeback = buffer_check_dirty_writeback, 1675}; 1676 1677const struct file_operations def_blk_fops = { 1678 .open = blkdev_open, 1679 .release = blkdev_close, 1680 .llseek = block_llseek, 1681 .read_iter = blkdev_read_iter, 1682 .write_iter = blkdev_write_iter, 1683 .mmap = generic_file_mmap, 1684 .fsync = blkdev_fsync, 1685 .unlocked_ioctl = block_ioctl, 1686#ifdef CONFIG_COMPAT 1687 .compat_ioctl = compat_blkdev_ioctl, 1688#endif 1689 .splice_read = generic_file_splice_read, 1690 .splice_write = iter_file_splice_write, 1691}; 1692 1693int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg) 1694{ 1695 int res; 1696 mm_segment_t old_fs = get_fs(); 1697 set_fs(KERNEL_DS); 1698 res = blkdev_ioctl(bdev, 0, cmd, arg); 1699 set_fs(old_fs); 1700 return res; 1701} 1702 1703EXPORT_SYMBOL(ioctl_by_bdev); 1704 1705/** 1706 * lookup_bdev - lookup a struct block_device by name 1707 * @pathname: special file representing the block device 1708 * 1709 * Get a reference to the blockdevice at @pathname in the current 1710 * namespace if possible and return it. Return ERR_PTR(error) 1711 * otherwise. 1712 */ 1713struct block_device *lookup_bdev(const char *pathname) 1714{ 1715 struct block_device *bdev; 1716 struct inode *inode; 1717 struct path path; 1718 int error; 1719 1720 if (!pathname || !*pathname) 1721 return ERR_PTR(-EINVAL); 1722 1723 error = kern_path(pathname, LOOKUP_FOLLOW, &path); 1724 if (error) 1725 return ERR_PTR(error); 1726 1727 inode = d_backing_inode(path.dentry); 1728 error = -ENOTBLK; 1729 if (!S_ISBLK(inode->i_mode)) 1730 goto fail; 1731 error = -EACCES; 1732 if (path.mnt->mnt_flags & MNT_NODEV) 1733 goto fail; 1734 error = -ENOMEM; 1735 bdev = bd_acquire(inode); 1736 if (!bdev) 1737 goto fail; 1738out: 1739 path_put(&path); 1740 return bdev; 1741fail: 1742 bdev = ERR_PTR(error); 1743 goto out; 1744} 1745EXPORT_SYMBOL(lookup_bdev); 1746 1747int __invalidate_device(struct block_device *bdev, bool kill_dirty) 1748{ 1749 struct super_block *sb = get_super(bdev); 1750 int res = 0; 1751 1752 if (sb) { 1753 /* 1754 * no need to lock the super, get_super holds the 1755 * read mutex so the filesystem cannot go away 1756 * under us (->put_super runs with the write lock 1757 * hold). 1758 */ 1759 shrink_dcache_sb(sb); 1760 res = invalidate_inodes(sb, kill_dirty); 1761 drop_super(sb); 1762 } 1763 invalidate_bdev(bdev); 1764 return res; 1765} 1766EXPORT_SYMBOL(__invalidate_device); 1767 1768void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg) 1769{ 1770 struct inode *inode, *old_inode = NULL; 1771 1772 spin_lock(&inode_sb_list_lock); 1773 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) { 1774 struct address_space *mapping = inode->i_mapping; 1775 1776 spin_lock(&inode->i_lock); 1777 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) || 1778 mapping->nrpages == 0) { 1779 spin_unlock(&inode->i_lock); 1780 continue; 1781 } 1782 __iget(inode); 1783 spin_unlock(&inode->i_lock); 1784 spin_unlock(&inode_sb_list_lock); 1785 /* 1786 * We hold a reference to 'inode' so it couldn't have been 1787 * removed from s_inodes list while we dropped the 1788 * inode_sb_list_lock. We cannot iput the inode now as we can 1789 * be holding the last reference and we cannot iput it under 1790 * inode_sb_list_lock. So we keep the reference and iput it 1791 * later. 1792 */ 1793 iput(old_inode); 1794 old_inode = inode; 1795 1796 func(I_BDEV(inode), arg); 1797 1798 spin_lock(&inode_sb_list_lock); 1799 } 1800 spin_unlock(&inode_sb_list_lock); 1801 iput(old_inode); 1802} 1803