1 /* 2 * linux/fs/super.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * 6 * super.c contains code to handle: - mount structures 7 * - super-block tables 8 * - filesystem drivers list 9 * - mount system call 10 * - umount system call 11 * - ustat system call 12 * 13 * GK 2/5/95 - Changed to support mounting the root fs via NFS 14 * 15 * Added kerneld support: Jacques Gelinas and Bjorn Ekwall 16 * Added change_root: Werner Almesberger & Hans Lermen, Feb '96 17 * Added options to /proc/mounts: 18 * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996. 19 * Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998 20 * Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000 21 */ 22 23 #include <linux/module.h> 24 #include <linux/slab.h> 25 #include <linux/init.h> 26 #include <linux/smp_lock.h> 27 #include <linux/acct.h> 28 #include <linux/blkdev.h> 29 #include <linux/quotaops.h> 30 #include <linux/namei.h> 31 #include <linux/buffer_head.h> /* for fsync_super() */ 32 #include <linux/mount.h> 33 #include <linux/security.h> 34 #include <linux/syscalls.h> 35 #include <linux/vfs.h> 36 #include <linux/writeback.h> /* for the emergency remount stuff */ 37 #include <linux/idr.h> 38 #include <linux/kobject.h> 39 #include <linux/mutex.h> 40 #include <linux/file.h> 41 #include <linux/async.h> 42 #include <asm/uaccess.h> 43 #include "internal.h" 44 45 46 LIST_HEAD(super_blocks); 47 DEFINE_SPINLOCK(sb_lock); 48 49 /** 50 * alloc_super - create new superblock 51 * @type: filesystem type superblock should belong to 52 * 53 * Allocates and initializes a new &struct super_block. alloc_super() 54 * returns a pointer new superblock or %NULL if allocation had failed. 55 */ 56 static struct super_block *alloc_super(struct file_system_type *type) 57 { 58 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); 59 static struct super_operations default_op; 60 61 if (s) { 62 if (security_sb_alloc(s)) { 63 kfree(s); 64 s = NULL; 65 goto out; 66 } 67 INIT_LIST_HEAD(&s->s_dirty); 68 INIT_LIST_HEAD(&s->s_io); 69 INIT_LIST_HEAD(&s->s_more_io); 70 INIT_LIST_HEAD(&s->s_files); 71 INIT_LIST_HEAD(&s->s_instances); 72 INIT_HLIST_HEAD(&s->s_anon); 73 INIT_LIST_HEAD(&s->s_inodes); 74 INIT_LIST_HEAD(&s->s_dentry_lru); 75 INIT_LIST_HEAD(&s->s_async_list); 76 init_rwsem(&s->s_umount); 77 mutex_init(&s->s_lock); 78 lockdep_set_class(&s->s_umount, &type->s_umount_key); 79 /* 80 * The locking rules for s_lock are up to the 81 * filesystem. For example ext3fs has different 82 * lock ordering than usbfs: 83 */ 84 lockdep_set_class(&s->s_lock, &type->s_lock_key); 85 /* 86 * sget() can have s_umount recursion. 87 * 88 * When it cannot find a suitable sb, it allocates a new 89 * one (this one), and tries again to find a suitable old 90 * one. 91 * 92 * In case that succeeds, it will acquire the s_umount 93 * lock of the old one. Since these are clearly distrinct 94 * locks, and this object isn't exposed yet, there's no 95 * risk of deadlocks. 96 * 97 * Annotate this by putting this lock in a different 98 * subclass. 99 */ 100 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); 101 s->s_count = S_BIAS; 102 atomic_set(&s->s_active, 1); 103 mutex_init(&s->s_vfs_rename_mutex); 104 mutex_init(&s->s_dquot.dqio_mutex); 105 mutex_init(&s->s_dquot.dqonoff_mutex); 106 init_rwsem(&s->s_dquot.dqptr_sem); 107 init_waitqueue_head(&s->s_wait_unfrozen); 108 s->s_maxbytes = MAX_NON_LFS; 109 s->dq_op = sb_dquot_ops; 110 s->s_qcop = sb_quotactl_ops; 111 s->s_op = &default_op; 112 s->s_time_gran = 1000000000; 113 } 114 out: 115 return s; 116 } 117 118 /** 119 * destroy_super - frees a superblock 120 * @s: superblock to free 121 * 122 * Frees a superblock. 123 */ 124 static inline void destroy_super(struct super_block *s) 125 { 126 security_sb_free(s); 127 kfree(s->s_subtype); 128 kfree(s->s_options); 129 kfree(s); 130 } 131 132 /* Superblock refcounting */ 133 134 /* 135 * Drop a superblock's refcount. Returns non-zero if the superblock was 136 * destroyed. The caller must hold sb_lock. 137 */ 138 static int __put_super(struct super_block *sb) 139 { 140 int ret = 0; 141 142 if (!--sb->s_count) { 143 destroy_super(sb); 144 ret = 1; 145 } 146 return ret; 147 } 148 149 /* 150 * Drop a superblock's refcount. 151 * Returns non-zero if the superblock is about to be destroyed and 152 * at least is already removed from super_blocks list, so if we are 153 * making a loop through super blocks then we need to restart. 154 * The caller must hold sb_lock. 155 */ 156 int __put_super_and_need_restart(struct super_block *sb) 157 { 158 /* check for race with generic_shutdown_super() */ 159 if (list_empty(&sb->s_list)) { 160 /* super block is removed, need to restart... */ 161 __put_super(sb); 162 return 1; 163 } 164 /* can't be the last, since s_list is still in use */ 165 sb->s_count--; 166 BUG_ON(sb->s_count == 0); 167 return 0; 168 } 169 170 /** 171 * put_super - drop a temporary reference to superblock 172 * @sb: superblock in question 173 * 174 * Drops a temporary reference, frees superblock if there's no 175 * references left. 176 */ 177 static void put_super(struct super_block *sb) 178 { 179 spin_lock(&sb_lock); 180 __put_super(sb); 181 spin_unlock(&sb_lock); 182 } 183 184 185 /** 186 * deactivate_super - drop an active reference to superblock 187 * @s: superblock to deactivate 188 * 189 * Drops an active reference to superblock, acquiring a temprory one if 190 * there is no active references left. In that case we lock superblock, 191 * tell fs driver to shut it down and drop the temporary reference we 192 * had just acquired. 193 */ 194 void deactivate_super(struct super_block *s) 195 { 196 struct file_system_type *fs = s->s_type; 197 if (atomic_dec_and_lock(&s->s_active, &sb_lock)) { 198 s->s_count -= S_BIAS-1; 199 spin_unlock(&sb_lock); 200 DQUOT_OFF(s, 0); 201 down_write(&s->s_umount); 202 fs->kill_sb(s); 203 put_filesystem(fs); 204 put_super(s); 205 } 206 } 207 208 EXPORT_SYMBOL(deactivate_super); 209 210 /** 211 * grab_super - acquire an active reference 212 * @s: reference we are trying to make active 213 * 214 * Tries to acquire an active reference. grab_super() is used when we 215 * had just found a superblock in super_blocks or fs_type->fs_supers 216 * and want to turn it into a full-blown active reference. grab_super() 217 * is called with sb_lock held and drops it. Returns 1 in case of 218 * success, 0 if we had failed (superblock contents was already dead or 219 * dying when grab_super() had been called). 220 */ 221 static int grab_super(struct super_block *s) __releases(sb_lock) 222 { 223 s->s_count++; 224 spin_unlock(&sb_lock); 225 down_write(&s->s_umount); 226 if (s->s_root) { 227 spin_lock(&sb_lock); 228 if (s->s_count > S_BIAS) { 229 atomic_inc(&s->s_active); 230 s->s_count--; 231 spin_unlock(&sb_lock); 232 return 1; 233 } 234 spin_unlock(&sb_lock); 235 } 236 up_write(&s->s_umount); 237 put_super(s); 238 yield(); 239 return 0; 240 } 241 242 /* 243 * Superblock locking. We really ought to get rid of these two. 244 */ 245 void lock_super(struct super_block * sb) 246 { 247 get_fs_excl(); 248 mutex_lock(&sb->s_lock); 249 } 250 251 void unlock_super(struct super_block * sb) 252 { 253 put_fs_excl(); 254 mutex_unlock(&sb->s_lock); 255 } 256 257 EXPORT_SYMBOL(lock_super); 258 EXPORT_SYMBOL(unlock_super); 259 260 /* 261 * Write out and wait upon all dirty data associated with this 262 * superblock. Filesystem data as well as the underlying block 263 * device. Takes the superblock lock. Requires a second blkdev 264 * flush by the caller to complete the operation. 265 */ 266 void __fsync_super(struct super_block *sb) 267 { 268 sync_inodes_sb(sb, 0); 269 DQUOT_SYNC(sb); 270 lock_super(sb); 271 if (sb->s_dirt && sb->s_op->write_super) 272 sb->s_op->write_super(sb); 273 unlock_super(sb); 274 if (sb->s_op->sync_fs) 275 sb->s_op->sync_fs(sb, 1); 276 sync_blockdev(sb->s_bdev); 277 sync_inodes_sb(sb, 1); 278 } 279 280 /* 281 * Write out and wait upon all dirty data associated with this 282 * superblock. Filesystem data as well as the underlying block 283 * device. Takes the superblock lock. 284 */ 285 int fsync_super(struct super_block *sb) 286 { 287 __fsync_super(sb); 288 return sync_blockdev(sb->s_bdev); 289 } 290 291 /** 292 * generic_shutdown_super - common helper for ->kill_sb() 293 * @sb: superblock to kill 294 * 295 * generic_shutdown_super() does all fs-independent work on superblock 296 * shutdown. Typical ->kill_sb() should pick all fs-specific objects 297 * that need destruction out of superblock, call generic_shutdown_super() 298 * and release aforementioned objects. Note: dentries and inodes _are_ 299 * taken care of and do not need specific handling. 300 * 301 * Upon calling this function, the filesystem may no longer alter or 302 * rearrange the set of dentries belonging to this super_block, nor may it 303 * change the attachments of dentries to inodes. 304 */ 305 void generic_shutdown_super(struct super_block *sb) 306 { 307 const struct super_operations *sop = sb->s_op; 308 309 310 if (sb->s_root) { 311 shrink_dcache_for_umount(sb); 312 fsync_super(sb); 313 lock_super(sb); 314 sb->s_flags &= ~MS_ACTIVE; 315 316 /* 317 * wait for asynchronous fs operations to finish before going further 318 */ 319 async_synchronize_full_domain(&sb->s_async_list); 320 321 /* bad name - it should be evict_inodes() */ 322 invalidate_inodes(sb); 323 lock_kernel(); 324 325 if (sop->write_super && sb->s_dirt) 326 sop->write_super(sb); 327 if (sop->put_super) 328 sop->put_super(sb); 329 330 /* Forget any remaining inodes */ 331 if (invalidate_inodes(sb)) { 332 printk("VFS: Busy inodes after unmount of %s. " 333 "Self-destruct in 5 seconds. Have a nice day...\n", 334 sb->s_id); 335 } 336 337 unlock_kernel(); 338 unlock_super(sb); 339 } 340 spin_lock(&sb_lock); 341 /* should be initialized for __put_super_and_need_restart() */ 342 list_del_init(&sb->s_list); 343 list_del(&sb->s_instances); 344 spin_unlock(&sb_lock); 345 up_write(&sb->s_umount); 346 } 347 348 EXPORT_SYMBOL(generic_shutdown_super); 349 350 /** 351 * sget - find or create a superblock 352 * @type: filesystem type superblock should belong to 353 * @test: comparison callback 354 * @set: setup callback 355 * @data: argument to each of them 356 */ 357 struct super_block *sget(struct file_system_type *type, 358 int (*test)(struct super_block *,void *), 359 int (*set)(struct super_block *,void *), 360 void *data) 361 { 362 struct super_block *s = NULL; 363 struct super_block *old; 364 int err; 365 366 retry: 367 spin_lock(&sb_lock); 368 if (test) { 369 list_for_each_entry(old, &type->fs_supers, s_instances) { 370 if (!test(old, data)) 371 continue; 372 if (!grab_super(old)) 373 goto retry; 374 if (s) { 375 up_write(&s->s_umount); 376 destroy_super(s); 377 } 378 return old; 379 } 380 } 381 if (!s) { 382 spin_unlock(&sb_lock); 383 s = alloc_super(type); 384 if (!s) 385 return ERR_PTR(-ENOMEM); 386 goto retry; 387 } 388 389 err = set(s, data); 390 if (err) { 391 spin_unlock(&sb_lock); 392 up_write(&s->s_umount); 393 destroy_super(s); 394 return ERR_PTR(err); 395 } 396 s->s_type = type; 397 strlcpy(s->s_id, type->name, sizeof(s->s_id)); 398 list_add_tail(&s->s_list, &super_blocks); 399 list_add(&s->s_instances, &type->fs_supers); 400 spin_unlock(&sb_lock); 401 get_filesystem(type); 402 return s; 403 } 404 405 EXPORT_SYMBOL(sget); 406 407 void drop_super(struct super_block *sb) 408 { 409 up_read(&sb->s_umount); 410 put_super(sb); 411 } 412 413 EXPORT_SYMBOL(drop_super); 414 415 static inline void write_super(struct super_block *sb) 416 { 417 lock_super(sb); 418 if (sb->s_root && sb->s_dirt) 419 if (sb->s_op->write_super) 420 sb->s_op->write_super(sb); 421 unlock_super(sb); 422 } 423 424 /* 425 * Note: check the dirty flag before waiting, so we don't 426 * hold up the sync while mounting a device. (The newly 427 * mounted device won't need syncing.) 428 */ 429 void sync_supers(void) 430 { 431 struct super_block *sb; 432 433 spin_lock(&sb_lock); 434 restart: 435 list_for_each_entry(sb, &super_blocks, s_list) { 436 if (sb->s_dirt) { 437 sb->s_count++; 438 spin_unlock(&sb_lock); 439 down_read(&sb->s_umount); 440 write_super(sb); 441 up_read(&sb->s_umount); 442 spin_lock(&sb_lock); 443 if (__put_super_and_need_restart(sb)) 444 goto restart; 445 } 446 } 447 spin_unlock(&sb_lock); 448 } 449 450 /* 451 * Call the ->sync_fs super_op against all filesystems which are r/w and 452 * which implement it. 453 * 454 * This operation is careful to avoid the livelock which could easily happen 455 * if two or more filesystems are being continuously dirtied. s_need_sync_fs 456 * is used only here. We set it against all filesystems and then clear it as 457 * we sync them. So redirtied filesystems are skipped. 458 * 459 * But if process A is currently running sync_filesystems and then process B 460 * calls sync_filesystems as well, process B will set all the s_need_sync_fs 461 * flags again, which will cause process A to resync everything. Fix that with 462 * a local mutex. 463 * 464 * (Fabian) Avoid sync_fs with clean fs & wait mode 0 465 */ 466 void sync_filesystems(int wait) 467 { 468 struct super_block *sb; 469 static DEFINE_MUTEX(mutex); 470 471 mutex_lock(&mutex); /* Could be down_interruptible */ 472 spin_lock(&sb_lock); 473 list_for_each_entry(sb, &super_blocks, s_list) { 474 if (!sb->s_op->sync_fs) 475 continue; 476 if (sb->s_flags & MS_RDONLY) 477 continue; 478 sb->s_need_sync_fs = 1; 479 } 480 481 restart: 482 list_for_each_entry(sb, &super_blocks, s_list) { 483 if (!sb->s_need_sync_fs) 484 continue; 485 sb->s_need_sync_fs = 0; 486 if (sb->s_flags & MS_RDONLY) 487 continue; /* hm. Was remounted r/o meanwhile */ 488 sb->s_count++; 489 spin_unlock(&sb_lock); 490 down_read(&sb->s_umount); 491 async_synchronize_full_domain(&sb->s_async_list); 492 if (sb->s_root && (wait || sb->s_dirt)) 493 sb->s_op->sync_fs(sb, wait); 494 up_read(&sb->s_umount); 495 /* restart only when sb is no longer on the list */ 496 spin_lock(&sb_lock); 497 if (__put_super_and_need_restart(sb)) 498 goto restart; 499 } 500 spin_unlock(&sb_lock); 501 mutex_unlock(&mutex); 502 } 503 504 /** 505 * get_super - get the superblock of a device 506 * @bdev: device to get the superblock for 507 * 508 * Scans the superblock list and finds the superblock of the file system 509 * mounted on the device given. %NULL is returned if no match is found. 510 */ 511 512 struct super_block * get_super(struct block_device *bdev) 513 { 514 struct super_block *sb; 515 516 if (!bdev) 517 return NULL; 518 519 spin_lock(&sb_lock); 520 rescan: 521 list_for_each_entry(sb, &super_blocks, s_list) { 522 if (sb->s_bdev == bdev) { 523 sb->s_count++; 524 spin_unlock(&sb_lock); 525 down_read(&sb->s_umount); 526 if (sb->s_root) 527 return sb; 528 up_read(&sb->s_umount); 529 /* restart only when sb is no longer on the list */ 530 spin_lock(&sb_lock); 531 if (__put_super_and_need_restart(sb)) 532 goto rescan; 533 } 534 } 535 spin_unlock(&sb_lock); 536 return NULL; 537 } 538 539 EXPORT_SYMBOL(get_super); 540 541 struct super_block * user_get_super(dev_t dev) 542 { 543 struct super_block *sb; 544 545 spin_lock(&sb_lock); 546 rescan: 547 list_for_each_entry(sb, &super_blocks, s_list) { 548 if (sb->s_dev == dev) { 549 sb->s_count++; 550 spin_unlock(&sb_lock); 551 down_read(&sb->s_umount); 552 if (sb->s_root) 553 return sb; 554 up_read(&sb->s_umount); 555 /* restart only when sb is no longer on the list */ 556 spin_lock(&sb_lock); 557 if (__put_super_and_need_restart(sb)) 558 goto rescan; 559 } 560 } 561 spin_unlock(&sb_lock); 562 return NULL; 563 } 564 565 SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf) 566 { 567 struct super_block *s; 568 struct ustat tmp; 569 struct kstatfs sbuf; 570 int err = -EINVAL; 571 572 s = user_get_super(new_decode_dev(dev)); 573 if (s == NULL) 574 goto out; 575 err = vfs_statfs(s->s_root, &sbuf); 576 drop_super(s); 577 if (err) 578 goto out; 579 580 memset(&tmp,0,sizeof(struct ustat)); 581 tmp.f_tfree = sbuf.f_bfree; 582 tmp.f_tinode = sbuf.f_ffree; 583 584 err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0; 585 out: 586 return err; 587 } 588 589 /** 590 * mark_files_ro - mark all files read-only 591 * @sb: superblock in question 592 * 593 * All files are marked read-only. We don't care about pending 594 * delete files so this should be used in 'force' mode only. 595 */ 596 597 static void mark_files_ro(struct super_block *sb) 598 { 599 struct file *f; 600 601 retry: 602 file_list_lock(); 603 list_for_each_entry(f, &sb->s_files, f_u.fu_list) { 604 struct vfsmount *mnt; 605 if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) 606 continue; 607 if (!file_count(f)) 608 continue; 609 if (!(f->f_mode & FMODE_WRITE)) 610 continue; 611 f->f_mode &= ~FMODE_WRITE; 612 if (file_check_writeable(f) != 0) 613 continue; 614 file_release_write(f); 615 mnt = mntget(f->f_path.mnt); 616 file_list_unlock(); 617 /* 618 * This can sleep, so we can't hold 619 * the file_list_lock() spinlock. 620 */ 621 mnt_drop_write(mnt); 622 mntput(mnt); 623 goto retry; 624 } 625 file_list_unlock(); 626 } 627 628 /** 629 * do_remount_sb - asks filesystem to change mount options. 630 * @sb: superblock in question 631 * @flags: numeric part of options 632 * @data: the rest of options 633 * @force: whether or not to force the change 634 * 635 * Alters the mount options of a mounted file system. 636 */ 637 int do_remount_sb(struct super_block *sb, int flags, void *data, int force) 638 { 639 int retval; 640 int remount_rw; 641 642 #ifdef CONFIG_BLOCK 643 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) 644 return -EACCES; 645 #endif 646 if (flags & MS_RDONLY) 647 acct_auto_close(sb); 648 shrink_dcache_sb(sb); 649 fsync_super(sb); 650 651 /* If we are remounting RDONLY and current sb is read/write, 652 make sure there are no rw files opened */ 653 if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) { 654 if (force) 655 mark_files_ro(sb); 656 else if (!fs_may_remount_ro(sb)) 657 return -EBUSY; 658 retval = DQUOT_OFF(sb, 1); 659 if (retval < 0 && retval != -ENOSYS) 660 return -EBUSY; 661 } 662 remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY); 663 664 if (sb->s_op->remount_fs) { 665 lock_super(sb); 666 retval = sb->s_op->remount_fs(sb, &flags, data); 667 unlock_super(sb); 668 if (retval) 669 return retval; 670 } 671 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); 672 if (remount_rw) 673 DQUOT_ON_REMOUNT(sb); 674 return 0; 675 } 676 677 static void do_emergency_remount(unsigned long foo) 678 { 679 struct super_block *sb; 680 681 spin_lock(&sb_lock); 682 list_for_each_entry(sb, &super_blocks, s_list) { 683 sb->s_count++; 684 spin_unlock(&sb_lock); 685 down_read(&sb->s_umount); 686 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) { 687 /* 688 * ->remount_fs needs lock_kernel(). 689 * 690 * What lock protects sb->s_flags?? 691 */ 692 lock_kernel(); 693 do_remount_sb(sb, MS_RDONLY, NULL, 1); 694 unlock_kernel(); 695 } 696 drop_super(sb); 697 spin_lock(&sb_lock); 698 } 699 spin_unlock(&sb_lock); 700 printk("Emergency Remount complete\n"); 701 } 702 703 void emergency_remount(void) 704 { 705 pdflush_operation(do_emergency_remount, 0); 706 } 707 708 /* 709 * Unnamed block devices are dummy devices used by virtual 710 * filesystems which don't use real block-devices. -- jrs 711 */ 712 713 static DEFINE_IDA(unnamed_dev_ida); 714 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ 715 716 int set_anon_super(struct super_block *s, void *data) 717 { 718 int dev; 719 int error; 720 721 retry: 722 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) 723 return -ENOMEM; 724 spin_lock(&unnamed_dev_lock); 725 error = ida_get_new(&unnamed_dev_ida, &dev); 726 spin_unlock(&unnamed_dev_lock); 727 if (error == -EAGAIN) 728 /* We raced and lost with another CPU. */ 729 goto retry; 730 else if (error) 731 return -EAGAIN; 732 733 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { 734 spin_lock(&unnamed_dev_lock); 735 ida_remove(&unnamed_dev_ida, dev); 736 spin_unlock(&unnamed_dev_lock); 737 return -EMFILE; 738 } 739 s->s_dev = MKDEV(0, dev & MINORMASK); 740 return 0; 741 } 742 743 EXPORT_SYMBOL(set_anon_super); 744 745 void kill_anon_super(struct super_block *sb) 746 { 747 int slot = MINOR(sb->s_dev); 748 749 generic_shutdown_super(sb); 750 spin_lock(&unnamed_dev_lock); 751 ida_remove(&unnamed_dev_ida, slot); 752 spin_unlock(&unnamed_dev_lock); 753 } 754 755 EXPORT_SYMBOL(kill_anon_super); 756 757 void kill_litter_super(struct super_block *sb) 758 { 759 if (sb->s_root) 760 d_genocide(sb->s_root); 761 kill_anon_super(sb); 762 } 763 764 EXPORT_SYMBOL(kill_litter_super); 765 766 #ifdef CONFIG_BLOCK 767 static int set_bdev_super(struct super_block *s, void *data) 768 { 769 s->s_bdev = data; 770 s->s_dev = s->s_bdev->bd_dev; 771 return 0; 772 } 773 774 static int test_bdev_super(struct super_block *s, void *data) 775 { 776 return (void *)s->s_bdev == data; 777 } 778 779 int get_sb_bdev(struct file_system_type *fs_type, 780 int flags, const char *dev_name, void *data, 781 int (*fill_super)(struct super_block *, void *, int), 782 struct vfsmount *mnt) 783 { 784 struct block_device *bdev; 785 struct super_block *s; 786 fmode_t mode = FMODE_READ; 787 int error = 0; 788 789 if (!(flags & MS_RDONLY)) 790 mode |= FMODE_WRITE; 791 792 bdev = open_bdev_exclusive(dev_name, mode, fs_type); 793 if (IS_ERR(bdev)) 794 return PTR_ERR(bdev); 795 796 /* 797 * once the super is inserted into the list by sget, s_umount 798 * will protect the lockfs code from trying to start a snapshot 799 * while we are mounting 800 */ 801 down(&bdev->bd_mount_sem); 802 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); 803 up(&bdev->bd_mount_sem); 804 if (IS_ERR(s)) 805 goto error_s; 806 807 if (s->s_root) { 808 if ((flags ^ s->s_flags) & MS_RDONLY) { 809 up_write(&s->s_umount); 810 deactivate_super(s); 811 error = -EBUSY; 812 goto error_bdev; 813 } 814 815 close_bdev_exclusive(bdev, mode); 816 } else { 817 char b[BDEVNAME_SIZE]; 818 819 s->s_flags = flags; 820 s->s_mode = mode; 821 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); 822 sb_set_blocksize(s, block_size(bdev)); 823 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); 824 if (error) { 825 up_write(&s->s_umount); 826 deactivate_super(s); 827 goto error; 828 } 829 830 s->s_flags |= MS_ACTIVE; 831 bdev->bd_super = s; 832 } 833 834 return simple_set_mnt(mnt, s); 835 836 error_s: 837 error = PTR_ERR(s); 838 error_bdev: 839 close_bdev_exclusive(bdev, mode); 840 error: 841 return error; 842 } 843 844 EXPORT_SYMBOL(get_sb_bdev); 845 846 void kill_block_super(struct super_block *sb) 847 { 848 struct block_device *bdev = sb->s_bdev; 849 fmode_t mode = sb->s_mode; 850 851 bdev->bd_super = 0; 852 generic_shutdown_super(sb); 853 sync_blockdev(bdev); 854 close_bdev_exclusive(bdev, mode); 855 } 856 857 EXPORT_SYMBOL(kill_block_super); 858 #endif 859 860 int get_sb_nodev(struct file_system_type *fs_type, 861 int flags, void *data, 862 int (*fill_super)(struct super_block *, void *, int), 863 struct vfsmount *mnt) 864 { 865 int error; 866 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); 867 868 if (IS_ERR(s)) 869 return PTR_ERR(s); 870 871 s->s_flags = flags; 872 873 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); 874 if (error) { 875 up_write(&s->s_umount); 876 deactivate_super(s); 877 return error; 878 } 879 s->s_flags |= MS_ACTIVE; 880 return simple_set_mnt(mnt, s); 881 } 882 883 EXPORT_SYMBOL(get_sb_nodev); 884 885 static int compare_single(struct super_block *s, void *p) 886 { 887 return 1; 888 } 889 890 int get_sb_single(struct file_system_type *fs_type, 891 int flags, void *data, 892 int (*fill_super)(struct super_block *, void *, int), 893 struct vfsmount *mnt) 894 { 895 struct super_block *s; 896 int error; 897 898 s = sget(fs_type, compare_single, set_anon_super, NULL); 899 if (IS_ERR(s)) 900 return PTR_ERR(s); 901 if (!s->s_root) { 902 s->s_flags = flags; 903 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); 904 if (error) { 905 up_write(&s->s_umount); 906 deactivate_super(s); 907 return error; 908 } 909 s->s_flags |= MS_ACTIVE; 910 } 911 do_remount_sb(s, flags, data, 0); 912 return simple_set_mnt(mnt, s); 913 } 914 915 EXPORT_SYMBOL(get_sb_single); 916 917 struct vfsmount * 918 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) 919 { 920 struct vfsmount *mnt; 921 char *secdata = NULL; 922 int error; 923 924 if (!type) 925 return ERR_PTR(-ENODEV); 926 927 error = -ENOMEM; 928 mnt = alloc_vfsmnt(name); 929 if (!mnt) 930 goto out; 931 932 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { 933 secdata = alloc_secdata(); 934 if (!secdata) 935 goto out_mnt; 936 937 error = security_sb_copy_data(data, secdata); 938 if (error) 939 goto out_free_secdata; 940 } 941 942 error = type->get_sb(type, flags, name, data, mnt); 943 if (error < 0) 944 goto out_free_secdata; 945 BUG_ON(!mnt->mnt_sb); 946 947 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata); 948 if (error) 949 goto out_sb; 950 951 mnt->mnt_mountpoint = mnt->mnt_root; 952 mnt->mnt_parent = mnt; 953 up_write(&mnt->mnt_sb->s_umount); 954 free_secdata(secdata); 955 return mnt; 956 out_sb: 957 dput(mnt->mnt_root); 958 up_write(&mnt->mnt_sb->s_umount); 959 deactivate_super(mnt->mnt_sb); 960 out_free_secdata: 961 free_secdata(secdata); 962 out_mnt: 963 free_vfsmnt(mnt); 964 out: 965 return ERR_PTR(error); 966 } 967 968 EXPORT_SYMBOL_GPL(vfs_kern_mount); 969 970 static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) 971 { 972 int err; 973 const char *subtype = strchr(fstype, '.'); 974 if (subtype) { 975 subtype++; 976 err = -EINVAL; 977 if (!subtype[0]) 978 goto err; 979 } else 980 subtype = ""; 981 982 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); 983 err = -ENOMEM; 984 if (!mnt->mnt_sb->s_subtype) 985 goto err; 986 return mnt; 987 988 err: 989 mntput(mnt); 990 return ERR_PTR(err); 991 } 992 993 struct vfsmount * 994 do_kern_mount(const char *fstype, int flags, const char *name, void *data) 995 { 996 struct file_system_type *type = get_fs_type(fstype); 997 struct vfsmount *mnt; 998 if (!type) 999 return ERR_PTR(-ENODEV); 1000 mnt = vfs_kern_mount(type, flags, name, data); 1001 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && 1002 !mnt->mnt_sb->s_subtype) 1003 mnt = fs_set_subtype(mnt, fstype); 1004 put_filesystem(type); 1005 return mnt; 1006 } 1007 EXPORT_SYMBOL_GPL(do_kern_mount); 1008 1009 struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) 1010 { 1011 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); 1012 } 1013 1014 EXPORT_SYMBOL_GPL(kern_mount_data); 1015