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