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/acct.h> 26 #include <linux/blkdev.h> 27 #include <linux/quotaops.h> 28 #include <linux/mount.h> 29 #include <linux/security.h> 30 #include <linux/writeback.h> /* for the emergency remount stuff */ 31 #include <linux/idr.h> 32 #include <linux/mutex.h> 33 #include <linux/backing-dev.h> 34 #include "internal.h" 35 36 37 LIST_HEAD(super_blocks); 38 DEFINE_SPINLOCK(sb_lock); 39 40 /** 41 * alloc_super - create new superblock 42 * @type: filesystem type superblock should belong to 43 * 44 * Allocates and initializes a new &struct super_block. alloc_super() 45 * returns a pointer new superblock or %NULL if allocation had failed. 46 */ 47 static struct super_block *alloc_super(struct file_system_type *type) 48 { 49 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); 50 static const struct super_operations default_op; 51 52 if (s) { 53 if (security_sb_alloc(s)) { 54 kfree(s); 55 s = NULL; 56 goto out; 57 } 58 INIT_LIST_HEAD(&s->s_files); 59 INIT_LIST_HEAD(&s->s_instances); 60 INIT_HLIST_HEAD(&s->s_anon); 61 INIT_LIST_HEAD(&s->s_inodes); 62 INIT_LIST_HEAD(&s->s_dentry_lru); 63 init_rwsem(&s->s_umount); 64 mutex_init(&s->s_lock); 65 lockdep_set_class(&s->s_umount, &type->s_umount_key); 66 /* 67 * The locking rules for s_lock are up to the 68 * filesystem. For example ext3fs has different 69 * lock ordering than usbfs: 70 */ 71 lockdep_set_class(&s->s_lock, &type->s_lock_key); 72 /* 73 * sget() can have s_umount recursion. 74 * 75 * When it cannot find a suitable sb, it allocates a new 76 * one (this one), and tries again to find a suitable old 77 * one. 78 * 79 * In case that succeeds, it will acquire the s_umount 80 * lock of the old one. Since these are clearly distrinct 81 * locks, and this object isn't exposed yet, there's no 82 * risk of deadlocks. 83 * 84 * Annotate this by putting this lock in a different 85 * subclass. 86 */ 87 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); 88 s->s_count = 1; 89 atomic_set(&s->s_active, 1); 90 mutex_init(&s->s_vfs_rename_mutex); 91 lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key); 92 mutex_init(&s->s_dquot.dqio_mutex); 93 mutex_init(&s->s_dquot.dqonoff_mutex); 94 init_rwsem(&s->s_dquot.dqptr_sem); 95 init_waitqueue_head(&s->s_wait_unfrozen); 96 s->s_maxbytes = MAX_NON_LFS; 97 s->dq_op = sb_dquot_ops; 98 s->s_qcop = sb_quotactl_ops; 99 s->s_op = &default_op; 100 s->s_time_gran = 1000000000; 101 } 102 out: 103 return s; 104 } 105 106 /** 107 * destroy_super - frees a superblock 108 * @s: superblock to free 109 * 110 * Frees a superblock. 111 */ 112 static inline void destroy_super(struct super_block *s) 113 { 114 security_sb_free(s); 115 kfree(s->s_subtype); 116 kfree(s->s_options); 117 kfree(s); 118 } 119 120 /* Superblock refcounting */ 121 122 /* 123 * Drop a superblock's refcount. The caller must hold sb_lock. 124 */ 125 void __put_super(struct super_block *sb) 126 { 127 if (!--sb->s_count) { 128 list_del_init(&sb->s_list); 129 destroy_super(sb); 130 } 131 } 132 133 /** 134 * put_super - drop a temporary reference to superblock 135 * @sb: superblock in question 136 * 137 * Drops a temporary reference, frees superblock if there's no 138 * references left. 139 */ 140 void put_super(struct super_block *sb) 141 { 142 spin_lock(&sb_lock); 143 __put_super(sb); 144 spin_unlock(&sb_lock); 145 } 146 147 148 /** 149 * deactivate_locked_super - drop an active reference to superblock 150 * @s: superblock to deactivate 151 * 152 * Drops an active reference to superblock, converting it into a temprory 153 * one if there is no other active references left. In that case we 154 * tell fs driver to shut it down and drop the temporary reference we 155 * had just acquired. 156 * 157 * Caller holds exclusive lock on superblock; that lock is released. 158 */ 159 void deactivate_locked_super(struct super_block *s) 160 { 161 struct file_system_type *fs = s->s_type; 162 if (atomic_dec_and_test(&s->s_active)) { 163 vfs_dq_off(s, 0); 164 fs->kill_sb(s); 165 put_filesystem(fs); 166 put_super(s); 167 } else { 168 up_write(&s->s_umount); 169 } 170 } 171 172 EXPORT_SYMBOL(deactivate_locked_super); 173 174 /** 175 * deactivate_super - drop an active reference to superblock 176 * @s: superblock to deactivate 177 * 178 * Variant of deactivate_locked_super(), except that superblock is *not* 179 * locked by caller. If we are going to drop the final active reference, 180 * lock will be acquired prior to that. 181 */ 182 void deactivate_super(struct super_block *s) 183 { 184 if (!atomic_add_unless(&s->s_active, -1, 1)) { 185 down_write(&s->s_umount); 186 deactivate_locked_super(s); 187 } 188 } 189 190 EXPORT_SYMBOL(deactivate_super); 191 192 /** 193 * grab_super - acquire an active reference 194 * @s: reference we are trying to make active 195 * 196 * Tries to acquire an active reference. grab_super() is used when we 197 * had just found a superblock in super_blocks or fs_type->fs_supers 198 * and want to turn it into a full-blown active reference. grab_super() 199 * is called with sb_lock held and drops it. Returns 1 in case of 200 * success, 0 if we had failed (superblock contents was already dead or 201 * dying when grab_super() had been called). 202 */ 203 static int grab_super(struct super_block *s) __releases(sb_lock) 204 { 205 if (atomic_inc_not_zero(&s->s_active)) { 206 spin_unlock(&sb_lock); 207 return 1; 208 } 209 /* it's going away */ 210 s->s_count++; 211 spin_unlock(&sb_lock); 212 /* wait for it to die */ 213 down_write(&s->s_umount); 214 up_write(&s->s_umount); 215 put_super(s); 216 return 0; 217 } 218 219 /* 220 * Superblock locking. We really ought to get rid of these two. 221 */ 222 void lock_super(struct super_block * sb) 223 { 224 get_fs_excl(); 225 mutex_lock(&sb->s_lock); 226 } 227 228 void unlock_super(struct super_block * sb) 229 { 230 put_fs_excl(); 231 mutex_unlock(&sb->s_lock); 232 } 233 234 EXPORT_SYMBOL(lock_super); 235 EXPORT_SYMBOL(unlock_super); 236 237 /** 238 * generic_shutdown_super - common helper for ->kill_sb() 239 * @sb: superblock to kill 240 * 241 * generic_shutdown_super() does all fs-independent work on superblock 242 * shutdown. Typical ->kill_sb() should pick all fs-specific objects 243 * that need destruction out of superblock, call generic_shutdown_super() 244 * and release aforementioned objects. Note: dentries and inodes _are_ 245 * taken care of and do not need specific handling. 246 * 247 * Upon calling this function, the filesystem may no longer alter or 248 * rearrange the set of dentries belonging to this super_block, nor may it 249 * change the attachments of dentries to inodes. 250 */ 251 void generic_shutdown_super(struct super_block *sb) 252 { 253 const struct super_operations *sop = sb->s_op; 254 255 256 if (sb->s_root) { 257 shrink_dcache_for_umount(sb); 258 sync_filesystem(sb); 259 get_fs_excl(); 260 sb->s_flags &= ~MS_ACTIVE; 261 262 /* bad name - it should be evict_inodes() */ 263 invalidate_inodes(sb); 264 265 if (sop->put_super) 266 sop->put_super(sb); 267 268 /* Forget any remaining inodes */ 269 if (invalidate_inodes(sb)) { 270 printk("VFS: Busy inodes after unmount of %s. " 271 "Self-destruct in 5 seconds. Have a nice day...\n", 272 sb->s_id); 273 } 274 put_fs_excl(); 275 } 276 spin_lock(&sb_lock); 277 /* should be initialized for __put_super_and_need_restart() */ 278 list_del_init(&sb->s_instances); 279 spin_unlock(&sb_lock); 280 up_write(&sb->s_umount); 281 } 282 283 EXPORT_SYMBOL(generic_shutdown_super); 284 285 /** 286 * sget - find or create a superblock 287 * @type: filesystem type superblock should belong to 288 * @test: comparison callback 289 * @set: setup callback 290 * @data: argument to each of them 291 */ 292 struct super_block *sget(struct file_system_type *type, 293 int (*test)(struct super_block *,void *), 294 int (*set)(struct super_block *,void *), 295 void *data) 296 { 297 struct super_block *s = NULL; 298 struct super_block *old; 299 int err; 300 301 retry: 302 spin_lock(&sb_lock); 303 if (test) { 304 list_for_each_entry(old, &type->fs_supers, s_instances) { 305 if (!test(old, data)) 306 continue; 307 if (!grab_super(old)) 308 goto retry; 309 if (s) { 310 up_write(&s->s_umount); 311 destroy_super(s); 312 } 313 down_write(&old->s_umount); 314 return old; 315 } 316 } 317 if (!s) { 318 spin_unlock(&sb_lock); 319 s = alloc_super(type); 320 if (!s) 321 return ERR_PTR(-ENOMEM); 322 goto retry; 323 } 324 325 err = set(s, data); 326 if (err) { 327 spin_unlock(&sb_lock); 328 up_write(&s->s_umount); 329 destroy_super(s); 330 return ERR_PTR(err); 331 } 332 s->s_type = type; 333 strlcpy(s->s_id, type->name, sizeof(s->s_id)); 334 list_add_tail(&s->s_list, &super_blocks); 335 list_add(&s->s_instances, &type->fs_supers); 336 spin_unlock(&sb_lock); 337 get_filesystem(type); 338 return s; 339 } 340 341 EXPORT_SYMBOL(sget); 342 343 void drop_super(struct super_block *sb) 344 { 345 up_read(&sb->s_umount); 346 put_super(sb); 347 } 348 349 EXPORT_SYMBOL(drop_super); 350 351 /** 352 * sync_supers - helper for periodic superblock writeback 353 * 354 * Call the write_super method if present on all dirty superblocks in 355 * the system. This is for the periodic writeback used by most older 356 * filesystems. For data integrity superblock writeback use 357 * sync_filesystems() instead. 358 * 359 * Note: check the dirty flag before waiting, so we don't 360 * hold up the sync while mounting a device. (The newly 361 * mounted device won't need syncing.) 362 */ 363 void sync_supers(void) 364 { 365 struct super_block *sb, *n; 366 367 spin_lock(&sb_lock); 368 list_for_each_entry_safe(sb, n, &super_blocks, s_list) { 369 if (list_empty(&sb->s_instances)) 370 continue; 371 if (sb->s_op->write_super && sb->s_dirt) { 372 sb->s_count++; 373 spin_unlock(&sb_lock); 374 375 down_read(&sb->s_umount); 376 if (sb->s_root && sb->s_dirt) 377 sb->s_op->write_super(sb); 378 up_read(&sb->s_umount); 379 380 spin_lock(&sb_lock); 381 __put_super(sb); 382 } 383 } 384 spin_unlock(&sb_lock); 385 } 386 387 /** 388 * iterate_supers - call function for all active superblocks 389 * @f: function to call 390 * @arg: argument to pass to it 391 * 392 * Scans the superblock list and calls given function, passing it 393 * locked superblock and given argument. 394 */ 395 void iterate_supers(void (*f)(struct super_block *, void *), void *arg) 396 { 397 struct super_block *sb, *n; 398 399 spin_lock(&sb_lock); 400 list_for_each_entry_safe(sb, n, &super_blocks, s_list) { 401 if (list_empty(&sb->s_instances)) 402 continue; 403 sb->s_count++; 404 spin_unlock(&sb_lock); 405 406 down_read(&sb->s_umount); 407 if (sb->s_root) 408 f(sb, arg); 409 up_read(&sb->s_umount); 410 411 spin_lock(&sb_lock); 412 __put_super(sb); 413 } 414 spin_unlock(&sb_lock); 415 } 416 417 /** 418 * get_super - get the superblock of a device 419 * @bdev: device to get the superblock for 420 * 421 * Scans the superblock list and finds the superblock of the file system 422 * mounted on the device given. %NULL is returned if no match is found. 423 */ 424 425 struct super_block *get_super(struct block_device *bdev) 426 { 427 struct super_block *sb; 428 429 if (!bdev) 430 return NULL; 431 432 spin_lock(&sb_lock); 433 rescan: 434 list_for_each_entry(sb, &super_blocks, s_list) { 435 if (list_empty(&sb->s_instances)) 436 continue; 437 if (sb->s_bdev == bdev) { 438 sb->s_count++; 439 spin_unlock(&sb_lock); 440 down_read(&sb->s_umount); 441 /* still alive? */ 442 if (sb->s_root) 443 return sb; 444 up_read(&sb->s_umount); 445 /* nope, got unmounted */ 446 spin_lock(&sb_lock); 447 __put_super(sb); 448 goto rescan; 449 } 450 } 451 spin_unlock(&sb_lock); 452 return NULL; 453 } 454 455 EXPORT_SYMBOL(get_super); 456 457 /** 458 * get_active_super - get an active reference to the superblock of a device 459 * @bdev: device to get the superblock for 460 * 461 * Scans the superblock list and finds the superblock of the file system 462 * mounted on the device given. Returns the superblock with an active 463 * reference or %NULL if none was found. 464 */ 465 struct super_block *get_active_super(struct block_device *bdev) 466 { 467 struct super_block *sb; 468 469 if (!bdev) 470 return NULL; 471 472 restart: 473 spin_lock(&sb_lock); 474 list_for_each_entry(sb, &super_blocks, s_list) { 475 if (list_empty(&sb->s_instances)) 476 continue; 477 if (sb->s_bdev == bdev) { 478 if (grab_super(sb)) /* drops sb_lock */ 479 return sb; 480 else 481 goto restart; 482 } 483 } 484 spin_unlock(&sb_lock); 485 return NULL; 486 } 487 488 struct super_block *user_get_super(dev_t dev) 489 { 490 struct super_block *sb; 491 492 spin_lock(&sb_lock); 493 rescan: 494 list_for_each_entry(sb, &super_blocks, s_list) { 495 if (list_empty(&sb->s_instances)) 496 continue; 497 if (sb->s_dev == dev) { 498 sb->s_count++; 499 spin_unlock(&sb_lock); 500 down_read(&sb->s_umount); 501 /* still alive? */ 502 if (sb->s_root) 503 return sb; 504 up_read(&sb->s_umount); 505 /* nope, got unmounted */ 506 spin_lock(&sb_lock); 507 __put_super(sb); 508 goto rescan; 509 } 510 } 511 spin_unlock(&sb_lock); 512 return NULL; 513 } 514 515 /** 516 * do_remount_sb - asks filesystem to change mount options. 517 * @sb: superblock in question 518 * @flags: numeric part of options 519 * @data: the rest of options 520 * @force: whether or not to force the change 521 * 522 * Alters the mount options of a mounted file system. 523 */ 524 int do_remount_sb(struct super_block *sb, int flags, void *data, int force) 525 { 526 int retval; 527 int remount_rw, remount_ro; 528 529 if (sb->s_frozen != SB_UNFROZEN) 530 return -EBUSY; 531 532 #ifdef CONFIG_BLOCK 533 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) 534 return -EACCES; 535 #endif 536 537 if (flags & MS_RDONLY) 538 acct_auto_close(sb); 539 shrink_dcache_sb(sb); 540 sync_filesystem(sb); 541 542 remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); 543 remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY); 544 545 /* If we are remounting RDONLY and current sb is read/write, 546 make sure there are no rw files opened */ 547 if (remount_ro) { 548 if (force) 549 mark_files_ro(sb); 550 else if (!fs_may_remount_ro(sb)) 551 return -EBUSY; 552 retval = vfs_dq_off(sb, 1); 553 if (retval < 0 && retval != -ENOSYS) 554 return -EBUSY; 555 } 556 557 if (sb->s_op->remount_fs) { 558 retval = sb->s_op->remount_fs(sb, &flags, data); 559 if (retval) 560 return retval; 561 } 562 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); 563 if (remount_rw) 564 vfs_dq_quota_on_remount(sb); 565 /* 566 * Some filesystems modify their metadata via some other path than the 567 * bdev buffer cache (eg. use a private mapping, or directories in 568 * pagecache, etc). Also file data modifications go via their own 569 * mappings. So If we try to mount readonly then copy the filesystem 570 * from bdev, we could get stale data, so invalidate it to give a best 571 * effort at coherency. 572 */ 573 if (remount_ro && sb->s_bdev) 574 invalidate_bdev(sb->s_bdev); 575 return 0; 576 } 577 578 static void do_emergency_remount(struct work_struct *work) 579 { 580 struct super_block *sb, *n; 581 582 spin_lock(&sb_lock); 583 list_for_each_entry_safe(sb, n, &super_blocks, s_list) { 584 if (list_empty(&sb->s_instances)) 585 continue; 586 sb->s_count++; 587 spin_unlock(&sb_lock); 588 down_write(&sb->s_umount); 589 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) { 590 /* 591 * What lock protects sb->s_flags?? 592 */ 593 do_remount_sb(sb, MS_RDONLY, NULL, 1); 594 } 595 up_write(&sb->s_umount); 596 spin_lock(&sb_lock); 597 __put_super(sb); 598 } 599 spin_unlock(&sb_lock); 600 kfree(work); 601 printk("Emergency Remount complete\n"); 602 } 603 604 void emergency_remount(void) 605 { 606 struct work_struct *work; 607 608 work = kmalloc(sizeof(*work), GFP_ATOMIC); 609 if (work) { 610 INIT_WORK(work, do_emergency_remount); 611 schedule_work(work); 612 } 613 } 614 615 /* 616 * Unnamed block devices are dummy devices used by virtual 617 * filesystems which don't use real block-devices. -- jrs 618 */ 619 620 static DEFINE_IDA(unnamed_dev_ida); 621 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ 622 static int unnamed_dev_start = 0; /* don't bother trying below it */ 623 624 int set_anon_super(struct super_block *s, void *data) 625 { 626 int dev; 627 int error; 628 629 retry: 630 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) 631 return -ENOMEM; 632 spin_lock(&unnamed_dev_lock); 633 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev); 634 if (!error) 635 unnamed_dev_start = dev + 1; 636 spin_unlock(&unnamed_dev_lock); 637 if (error == -EAGAIN) 638 /* We raced and lost with another CPU. */ 639 goto retry; 640 else if (error) 641 return -EAGAIN; 642 643 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { 644 spin_lock(&unnamed_dev_lock); 645 ida_remove(&unnamed_dev_ida, dev); 646 if (unnamed_dev_start > dev) 647 unnamed_dev_start = dev; 648 spin_unlock(&unnamed_dev_lock); 649 return -EMFILE; 650 } 651 s->s_dev = MKDEV(0, dev & MINORMASK); 652 s->s_bdi = &noop_backing_dev_info; 653 return 0; 654 } 655 656 EXPORT_SYMBOL(set_anon_super); 657 658 void kill_anon_super(struct super_block *sb) 659 { 660 int slot = MINOR(sb->s_dev); 661 662 generic_shutdown_super(sb); 663 spin_lock(&unnamed_dev_lock); 664 ida_remove(&unnamed_dev_ida, slot); 665 if (slot < unnamed_dev_start) 666 unnamed_dev_start = slot; 667 spin_unlock(&unnamed_dev_lock); 668 } 669 670 EXPORT_SYMBOL(kill_anon_super); 671 672 void kill_litter_super(struct super_block *sb) 673 { 674 if (sb->s_root) 675 d_genocide(sb->s_root); 676 kill_anon_super(sb); 677 } 678 679 EXPORT_SYMBOL(kill_litter_super); 680 681 static int ns_test_super(struct super_block *sb, void *data) 682 { 683 return sb->s_fs_info == data; 684 } 685 686 static int ns_set_super(struct super_block *sb, void *data) 687 { 688 sb->s_fs_info = data; 689 return set_anon_super(sb, NULL); 690 } 691 692 int get_sb_ns(struct file_system_type *fs_type, int flags, void *data, 693 int (*fill_super)(struct super_block *, void *, int), 694 struct vfsmount *mnt) 695 { 696 struct super_block *sb; 697 698 sb = sget(fs_type, ns_test_super, ns_set_super, data); 699 if (IS_ERR(sb)) 700 return PTR_ERR(sb); 701 702 if (!sb->s_root) { 703 int err; 704 sb->s_flags = flags; 705 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); 706 if (err) { 707 deactivate_locked_super(sb); 708 return err; 709 } 710 711 sb->s_flags |= MS_ACTIVE; 712 } 713 714 simple_set_mnt(mnt, sb); 715 return 0; 716 } 717 718 EXPORT_SYMBOL(get_sb_ns); 719 720 #ifdef CONFIG_BLOCK 721 static int set_bdev_super(struct super_block *s, void *data) 722 { 723 s->s_bdev = data; 724 s->s_dev = s->s_bdev->bd_dev; 725 726 /* 727 * We set the bdi here to the queue backing, file systems can 728 * overwrite this in ->fill_super() 729 */ 730 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info; 731 return 0; 732 } 733 734 static int test_bdev_super(struct super_block *s, void *data) 735 { 736 return (void *)s->s_bdev == data; 737 } 738 739 int get_sb_bdev(struct file_system_type *fs_type, 740 int flags, const char *dev_name, void *data, 741 int (*fill_super)(struct super_block *, void *, int), 742 struct vfsmount *mnt) 743 { 744 struct block_device *bdev; 745 struct super_block *s; 746 fmode_t mode = FMODE_READ; 747 int error = 0; 748 749 if (!(flags & MS_RDONLY)) 750 mode |= FMODE_WRITE; 751 752 bdev = open_bdev_exclusive(dev_name, mode, fs_type); 753 if (IS_ERR(bdev)) 754 return PTR_ERR(bdev); 755 756 /* 757 * once the super is inserted into the list by sget, s_umount 758 * will protect the lockfs code from trying to start a snapshot 759 * while we are mounting 760 */ 761 mutex_lock(&bdev->bd_fsfreeze_mutex); 762 if (bdev->bd_fsfreeze_count > 0) { 763 mutex_unlock(&bdev->bd_fsfreeze_mutex); 764 error = -EBUSY; 765 goto error_bdev; 766 } 767 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); 768 mutex_unlock(&bdev->bd_fsfreeze_mutex); 769 if (IS_ERR(s)) 770 goto error_s; 771 772 if (s->s_root) { 773 if ((flags ^ s->s_flags) & MS_RDONLY) { 774 deactivate_locked_super(s); 775 error = -EBUSY; 776 goto error_bdev; 777 } 778 779 close_bdev_exclusive(bdev, mode); 780 } else { 781 char b[BDEVNAME_SIZE]; 782 783 s->s_flags = flags; 784 s->s_mode = mode; 785 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); 786 sb_set_blocksize(s, block_size(bdev)); 787 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); 788 if (error) { 789 deactivate_locked_super(s); 790 goto error; 791 } 792 793 s->s_flags |= MS_ACTIVE; 794 bdev->bd_super = s; 795 } 796 797 simple_set_mnt(mnt, s); 798 return 0; 799 800 error_s: 801 error = PTR_ERR(s); 802 error_bdev: 803 close_bdev_exclusive(bdev, mode); 804 error: 805 return error; 806 } 807 808 EXPORT_SYMBOL(get_sb_bdev); 809 810 void kill_block_super(struct super_block *sb) 811 { 812 struct block_device *bdev = sb->s_bdev; 813 fmode_t mode = sb->s_mode; 814 815 bdev->bd_super = NULL; 816 generic_shutdown_super(sb); 817 sync_blockdev(bdev); 818 close_bdev_exclusive(bdev, mode); 819 } 820 821 EXPORT_SYMBOL(kill_block_super); 822 #endif 823 824 int get_sb_nodev(struct file_system_type *fs_type, 825 int flags, void *data, 826 int (*fill_super)(struct super_block *, void *, int), 827 struct vfsmount *mnt) 828 { 829 int error; 830 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); 831 832 if (IS_ERR(s)) 833 return PTR_ERR(s); 834 835 s->s_flags = flags; 836 837 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); 838 if (error) { 839 deactivate_locked_super(s); 840 return error; 841 } 842 s->s_flags |= MS_ACTIVE; 843 simple_set_mnt(mnt, s); 844 return 0; 845 } 846 847 EXPORT_SYMBOL(get_sb_nodev); 848 849 static int compare_single(struct super_block *s, void *p) 850 { 851 return 1; 852 } 853 854 int get_sb_single(struct file_system_type *fs_type, 855 int flags, void *data, 856 int (*fill_super)(struct super_block *, void *, int), 857 struct vfsmount *mnt) 858 { 859 struct super_block *s; 860 int error; 861 862 s = sget(fs_type, compare_single, set_anon_super, NULL); 863 if (IS_ERR(s)) 864 return PTR_ERR(s); 865 if (!s->s_root) { 866 s->s_flags = flags; 867 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); 868 if (error) { 869 deactivate_locked_super(s); 870 return error; 871 } 872 s->s_flags |= MS_ACTIVE; 873 } else { 874 do_remount_sb(s, flags, data, 0); 875 } 876 simple_set_mnt(mnt, s); 877 return 0; 878 } 879 880 EXPORT_SYMBOL(get_sb_single); 881 882 struct vfsmount * 883 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) 884 { 885 struct vfsmount *mnt; 886 char *secdata = NULL; 887 int error; 888 889 if (!type) 890 return ERR_PTR(-ENODEV); 891 892 error = -ENOMEM; 893 mnt = alloc_vfsmnt(name); 894 if (!mnt) 895 goto out; 896 897 if (flags & MS_KERNMOUNT) 898 mnt->mnt_flags = MNT_INTERNAL; 899 900 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { 901 secdata = alloc_secdata(); 902 if (!secdata) 903 goto out_mnt; 904 905 error = security_sb_copy_data(data, secdata); 906 if (error) 907 goto out_free_secdata; 908 } 909 910 error = type->get_sb(type, flags, name, data, mnt); 911 if (error < 0) 912 goto out_free_secdata; 913 BUG_ON(!mnt->mnt_sb); 914 WARN_ON(!mnt->mnt_sb->s_bdi); 915 916 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata); 917 if (error) 918 goto out_sb; 919 920 /* 921 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE 922 * but s_maxbytes was an unsigned long long for many releases. Throw 923 * this warning for a little while to try and catch filesystems that 924 * violate this rule. This warning should be either removed or 925 * converted to a BUG() in 2.6.34. 926 */ 927 WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " 928 "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes); 929 930 mnt->mnt_mountpoint = mnt->mnt_root; 931 mnt->mnt_parent = mnt; 932 up_write(&mnt->mnt_sb->s_umount); 933 free_secdata(secdata); 934 return mnt; 935 out_sb: 936 dput(mnt->mnt_root); 937 deactivate_locked_super(mnt->mnt_sb); 938 out_free_secdata: 939 free_secdata(secdata); 940 out_mnt: 941 free_vfsmnt(mnt); 942 out: 943 return ERR_PTR(error); 944 } 945 946 EXPORT_SYMBOL_GPL(vfs_kern_mount); 947 948 /** 949 * freeze_super -- lock the filesystem and force it into a consistent state 950 * @super: the super to lock 951 * 952 * Syncs the super to make sure the filesystem is consistent and calls the fs's 953 * freeze_fs. Subsequent calls to this without first thawing the fs will return 954 * -EBUSY. 955 */ 956 int freeze_super(struct super_block *sb) 957 { 958 int ret; 959 960 atomic_inc(&sb->s_active); 961 down_write(&sb->s_umount); 962 if (sb->s_frozen) { 963 deactivate_locked_super(sb); 964 return -EBUSY; 965 } 966 967 if (sb->s_flags & MS_RDONLY) { 968 sb->s_frozen = SB_FREEZE_TRANS; 969 smp_wmb(); 970 up_write(&sb->s_umount); 971 return 0; 972 } 973 974 sb->s_frozen = SB_FREEZE_WRITE; 975 smp_wmb(); 976 977 sync_filesystem(sb); 978 979 sb->s_frozen = SB_FREEZE_TRANS; 980 smp_wmb(); 981 982 sync_blockdev(sb->s_bdev); 983 if (sb->s_op->freeze_fs) { 984 ret = sb->s_op->freeze_fs(sb); 985 if (ret) { 986 printk(KERN_ERR 987 "VFS:Filesystem freeze failed\n"); 988 sb->s_frozen = SB_UNFROZEN; 989 deactivate_locked_super(sb); 990 return ret; 991 } 992 } 993 up_write(&sb->s_umount); 994 return 0; 995 } 996 EXPORT_SYMBOL(freeze_super); 997 998 /** 999 * thaw_super -- unlock filesystem 1000 * @sb: the super to thaw 1001 * 1002 * Unlocks the filesystem and marks it writeable again after freeze_super(). 1003 */ 1004 int thaw_super(struct super_block *sb) 1005 { 1006 int error; 1007 1008 down_write(&sb->s_umount); 1009 if (sb->s_frozen == SB_UNFROZEN) { 1010 up_write(&sb->s_umount); 1011 return -EINVAL; 1012 } 1013 1014 if (sb->s_flags & MS_RDONLY) 1015 goto out; 1016 1017 if (sb->s_op->unfreeze_fs) { 1018 error = sb->s_op->unfreeze_fs(sb); 1019 if (error) { 1020 printk(KERN_ERR 1021 "VFS:Filesystem thaw failed\n"); 1022 sb->s_frozen = SB_FREEZE_TRANS; 1023 up_write(&sb->s_umount); 1024 return error; 1025 } 1026 } 1027 1028 out: 1029 sb->s_frozen = SB_UNFROZEN; 1030 smp_wmb(); 1031 wake_up(&sb->s_wait_unfrozen); 1032 deactivate_locked_super(sb); 1033 1034 return 0; 1035 } 1036 EXPORT_SYMBOL(thaw_super); 1037 1038 static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) 1039 { 1040 int err; 1041 const char *subtype = strchr(fstype, '.'); 1042 if (subtype) { 1043 subtype++; 1044 err = -EINVAL; 1045 if (!subtype[0]) 1046 goto err; 1047 } else 1048 subtype = ""; 1049 1050 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); 1051 err = -ENOMEM; 1052 if (!mnt->mnt_sb->s_subtype) 1053 goto err; 1054 return mnt; 1055 1056 err: 1057 mntput(mnt); 1058 return ERR_PTR(err); 1059 } 1060 1061 struct vfsmount * 1062 do_kern_mount(const char *fstype, int flags, const char *name, void *data) 1063 { 1064 struct file_system_type *type = get_fs_type(fstype); 1065 struct vfsmount *mnt; 1066 if (!type) 1067 return ERR_PTR(-ENODEV); 1068 mnt = vfs_kern_mount(type, flags, name, data); 1069 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && 1070 !mnt->mnt_sb->s_subtype) 1071 mnt = fs_set_subtype(mnt, fstype); 1072 put_filesystem(type); 1073 return mnt; 1074 } 1075 EXPORT_SYMBOL_GPL(do_kern_mount); 1076 1077 struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) 1078 { 1079 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); 1080 } 1081 1082 EXPORT_SYMBOL_GPL(kern_mount_data); 1083