1 /* 2 * fs/libfs.c 3 * Library for filesystems writers. 4 */ 5 6 #include <linux/module.h> 7 #include <linux/pagemap.h> 8 #include <linux/mount.h> 9 #include <linux/vfs.h> 10 #include <linux/mutex.h> 11 #include <linux/exportfs.h> 12 13 #include <asm/uaccess.h> 14 15 int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, 16 struct kstat *stat) 17 { 18 struct inode *inode = dentry->d_inode; 19 generic_fillattr(inode, stat); 20 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); 21 return 0; 22 } 23 24 int simple_statfs(struct dentry *dentry, struct kstatfs *buf) 25 { 26 buf->f_type = dentry->d_sb->s_magic; 27 buf->f_bsize = PAGE_CACHE_SIZE; 28 buf->f_namelen = NAME_MAX; 29 return 0; 30 } 31 32 /* 33 * Retaining negative dentries for an in-memory filesystem just wastes 34 * memory and lookup time: arrange for them to be deleted immediately. 35 */ 36 static int simple_delete_dentry(struct dentry *dentry) 37 { 38 return 1; 39 } 40 41 /* 42 * Lookup the data. This is trivial - if the dentry didn't already 43 * exist, we know it is negative. Set d_op to delete negative dentries. 44 */ 45 struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) 46 { 47 static const struct dentry_operations simple_dentry_operations = { 48 .d_delete = simple_delete_dentry, 49 }; 50 51 if (dentry->d_name.len > NAME_MAX) 52 return ERR_PTR(-ENAMETOOLONG); 53 dentry->d_op = &simple_dentry_operations; 54 d_add(dentry, NULL); 55 return NULL; 56 } 57 58 int simple_sync_file(struct file * file, struct dentry *dentry, int datasync) 59 { 60 return 0; 61 } 62 63 int dcache_dir_open(struct inode *inode, struct file *file) 64 { 65 static struct qstr cursor_name = {.len = 1, .name = "."}; 66 67 file->private_data = d_alloc(file->f_path.dentry, &cursor_name); 68 69 return file->private_data ? 0 : -ENOMEM; 70 } 71 72 int dcache_dir_close(struct inode *inode, struct file *file) 73 { 74 dput(file->private_data); 75 return 0; 76 } 77 78 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) 79 { 80 mutex_lock(&file->f_path.dentry->d_inode->i_mutex); 81 switch (origin) { 82 case 1: 83 offset += file->f_pos; 84 case 0: 85 if (offset >= 0) 86 break; 87 default: 88 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); 89 return -EINVAL; 90 } 91 if (offset != file->f_pos) { 92 file->f_pos = offset; 93 if (file->f_pos >= 2) { 94 struct list_head *p; 95 struct dentry *cursor = file->private_data; 96 loff_t n = file->f_pos - 2; 97 98 spin_lock(&dcache_lock); 99 list_del(&cursor->d_u.d_child); 100 p = file->f_path.dentry->d_subdirs.next; 101 while (n && p != &file->f_path.dentry->d_subdirs) { 102 struct dentry *next; 103 next = list_entry(p, struct dentry, d_u.d_child); 104 if (!d_unhashed(next) && next->d_inode) 105 n--; 106 p = p->next; 107 } 108 list_add_tail(&cursor->d_u.d_child, p); 109 spin_unlock(&dcache_lock); 110 } 111 } 112 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); 113 return offset; 114 } 115 116 /* Relationship between i_mode and the DT_xxx types */ 117 static inline unsigned char dt_type(struct inode *inode) 118 { 119 return (inode->i_mode >> 12) & 15; 120 } 121 122 /* 123 * Directory is locked and all positive dentries in it are safe, since 124 * for ramfs-type trees they can't go away without unlink() or rmdir(), 125 * both impossible due to the lock on directory. 126 */ 127 128 int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) 129 { 130 struct dentry *dentry = filp->f_path.dentry; 131 struct dentry *cursor = filp->private_data; 132 struct list_head *p, *q = &cursor->d_u.d_child; 133 ino_t ino; 134 int i = filp->f_pos; 135 136 switch (i) { 137 case 0: 138 ino = dentry->d_inode->i_ino; 139 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) 140 break; 141 filp->f_pos++; 142 i++; 143 /* fallthrough */ 144 case 1: 145 ino = parent_ino(dentry); 146 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) 147 break; 148 filp->f_pos++; 149 i++; 150 /* fallthrough */ 151 default: 152 spin_lock(&dcache_lock); 153 if (filp->f_pos == 2) 154 list_move(q, &dentry->d_subdirs); 155 156 for (p=q->next; p != &dentry->d_subdirs; p=p->next) { 157 struct dentry *next; 158 next = list_entry(p, struct dentry, d_u.d_child); 159 if (d_unhashed(next) || !next->d_inode) 160 continue; 161 162 spin_unlock(&dcache_lock); 163 if (filldir(dirent, next->d_name.name, 164 next->d_name.len, filp->f_pos, 165 next->d_inode->i_ino, 166 dt_type(next->d_inode)) < 0) 167 return 0; 168 spin_lock(&dcache_lock); 169 /* next is still alive */ 170 list_move(q, p); 171 p = q; 172 filp->f_pos++; 173 } 174 spin_unlock(&dcache_lock); 175 } 176 return 0; 177 } 178 179 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) 180 { 181 return -EISDIR; 182 } 183 184 const struct file_operations simple_dir_operations = { 185 .open = dcache_dir_open, 186 .release = dcache_dir_close, 187 .llseek = dcache_dir_lseek, 188 .read = generic_read_dir, 189 .readdir = dcache_readdir, 190 .fsync = simple_sync_file, 191 }; 192 193 const struct inode_operations simple_dir_inode_operations = { 194 .lookup = simple_lookup, 195 }; 196 197 static const struct super_operations simple_super_operations = { 198 .statfs = simple_statfs, 199 }; 200 201 /* 202 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that 203 * will never be mountable) 204 */ 205 int get_sb_pseudo(struct file_system_type *fs_type, char *name, 206 const struct super_operations *ops, unsigned long magic, 207 struct vfsmount *mnt) 208 { 209 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); 210 struct dentry *dentry; 211 struct inode *root; 212 struct qstr d_name = {.name = name, .len = strlen(name)}; 213 214 if (IS_ERR(s)) 215 return PTR_ERR(s); 216 217 s->s_flags = MS_NOUSER; 218 s->s_maxbytes = ~0ULL; 219 s->s_blocksize = PAGE_SIZE; 220 s->s_blocksize_bits = PAGE_SHIFT; 221 s->s_magic = magic; 222 s->s_op = ops ? ops : &simple_super_operations; 223 s->s_time_gran = 1; 224 root = new_inode(s); 225 if (!root) 226 goto Enomem; 227 /* 228 * since this is the first inode, make it number 1. New inodes created 229 * after this must take care not to collide with it (by passing 230 * max_reserved of 1 to iunique). 231 */ 232 root->i_ino = 1; 233 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; 234 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; 235 dentry = d_alloc(NULL, &d_name); 236 if (!dentry) { 237 iput(root); 238 goto Enomem; 239 } 240 dentry->d_sb = s; 241 dentry->d_parent = dentry; 242 d_instantiate(dentry, root); 243 s->s_root = dentry; 244 s->s_flags |= MS_ACTIVE; 245 simple_set_mnt(mnt, s); 246 return 0; 247 248 Enomem: 249 deactivate_locked_super(s); 250 return -ENOMEM; 251 } 252 253 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 254 { 255 struct inode *inode = old_dentry->d_inode; 256 257 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 258 inc_nlink(inode); 259 atomic_inc(&inode->i_count); 260 dget(dentry); 261 d_instantiate(dentry, inode); 262 return 0; 263 } 264 265 static inline int simple_positive(struct dentry *dentry) 266 { 267 return dentry->d_inode && !d_unhashed(dentry); 268 } 269 270 int simple_empty(struct dentry *dentry) 271 { 272 struct dentry *child; 273 int ret = 0; 274 275 spin_lock(&dcache_lock); 276 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) 277 if (simple_positive(child)) 278 goto out; 279 ret = 1; 280 out: 281 spin_unlock(&dcache_lock); 282 return ret; 283 } 284 285 int simple_unlink(struct inode *dir, struct dentry *dentry) 286 { 287 struct inode *inode = dentry->d_inode; 288 289 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 290 drop_nlink(inode); 291 dput(dentry); 292 return 0; 293 } 294 295 int simple_rmdir(struct inode *dir, struct dentry *dentry) 296 { 297 if (!simple_empty(dentry)) 298 return -ENOTEMPTY; 299 300 drop_nlink(dentry->d_inode); 301 simple_unlink(dir, dentry); 302 drop_nlink(dir); 303 return 0; 304 } 305 306 int simple_rename(struct inode *old_dir, struct dentry *old_dentry, 307 struct inode *new_dir, struct dentry *new_dentry) 308 { 309 struct inode *inode = old_dentry->d_inode; 310 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); 311 312 if (!simple_empty(new_dentry)) 313 return -ENOTEMPTY; 314 315 if (new_dentry->d_inode) { 316 simple_unlink(new_dir, new_dentry); 317 if (they_are_dirs) 318 drop_nlink(old_dir); 319 } else if (they_are_dirs) { 320 drop_nlink(old_dir); 321 inc_nlink(new_dir); 322 } 323 324 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = 325 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; 326 327 return 0; 328 } 329 330 int simple_readpage(struct file *file, struct page *page) 331 { 332 clear_highpage(page); 333 flush_dcache_page(page); 334 SetPageUptodate(page); 335 unlock_page(page); 336 return 0; 337 } 338 339 int simple_prepare_write(struct file *file, struct page *page, 340 unsigned from, unsigned to) 341 { 342 if (!PageUptodate(page)) { 343 if (to - from != PAGE_CACHE_SIZE) 344 zero_user_segments(page, 345 0, from, 346 to, PAGE_CACHE_SIZE); 347 } 348 return 0; 349 } 350 351 int simple_write_begin(struct file *file, struct address_space *mapping, 352 loff_t pos, unsigned len, unsigned flags, 353 struct page **pagep, void **fsdata) 354 { 355 struct page *page; 356 pgoff_t index; 357 unsigned from; 358 359 index = pos >> PAGE_CACHE_SHIFT; 360 from = pos & (PAGE_CACHE_SIZE - 1); 361 362 page = grab_cache_page_write_begin(mapping, index, flags); 363 if (!page) 364 return -ENOMEM; 365 366 *pagep = page; 367 368 return simple_prepare_write(file, page, from, from+len); 369 } 370 371 static int simple_commit_write(struct file *file, struct page *page, 372 unsigned from, unsigned to) 373 { 374 struct inode *inode = page->mapping->host; 375 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; 376 377 if (!PageUptodate(page)) 378 SetPageUptodate(page); 379 /* 380 * No need to use i_size_read() here, the i_size 381 * cannot change under us because we hold the i_mutex. 382 */ 383 if (pos > inode->i_size) 384 i_size_write(inode, pos); 385 set_page_dirty(page); 386 return 0; 387 } 388 389 int simple_write_end(struct file *file, struct address_space *mapping, 390 loff_t pos, unsigned len, unsigned copied, 391 struct page *page, void *fsdata) 392 { 393 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 394 395 /* zero the stale part of the page if we did a short copy */ 396 if (copied < len) { 397 void *kaddr = kmap_atomic(page, KM_USER0); 398 memset(kaddr + from + copied, 0, len - copied); 399 flush_dcache_page(page); 400 kunmap_atomic(kaddr, KM_USER0); 401 } 402 403 simple_commit_write(file, page, from, from+copied); 404 405 unlock_page(page); 406 page_cache_release(page); 407 408 return copied; 409 } 410 411 /* 412 * the inodes created here are not hashed. If you use iunique to generate 413 * unique inode values later for this filesystem, then you must take care 414 * to pass it an appropriate max_reserved value to avoid collisions. 415 */ 416 int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files) 417 { 418 struct inode *inode; 419 struct dentry *root; 420 struct dentry *dentry; 421 int i; 422 423 s->s_blocksize = PAGE_CACHE_SIZE; 424 s->s_blocksize_bits = PAGE_CACHE_SHIFT; 425 s->s_magic = magic; 426 s->s_op = &simple_super_operations; 427 s->s_time_gran = 1; 428 429 inode = new_inode(s); 430 if (!inode) 431 return -ENOMEM; 432 /* 433 * because the root inode is 1, the files array must not contain an 434 * entry at index 1 435 */ 436 inode->i_ino = 1; 437 inode->i_mode = S_IFDIR | 0755; 438 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 439 inode->i_op = &simple_dir_inode_operations; 440 inode->i_fop = &simple_dir_operations; 441 inode->i_nlink = 2; 442 root = d_alloc_root(inode); 443 if (!root) { 444 iput(inode); 445 return -ENOMEM; 446 } 447 for (i = 0; !files->name || files->name[0]; i++, files++) { 448 if (!files->name) 449 continue; 450 451 /* warn if it tries to conflict with the root inode */ 452 if (unlikely(i == 1)) 453 printk(KERN_WARNING "%s: %s passed in a files array" 454 "with an index of 1!\n", __func__, 455 s->s_type->name); 456 457 dentry = d_alloc_name(root, files->name); 458 if (!dentry) 459 goto out; 460 inode = new_inode(s); 461 if (!inode) 462 goto out; 463 inode->i_mode = S_IFREG | files->mode; 464 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 465 inode->i_fop = files->ops; 466 inode->i_ino = i; 467 d_add(dentry, inode); 468 } 469 s->s_root = root; 470 return 0; 471 out: 472 d_genocide(root); 473 dput(root); 474 return -ENOMEM; 475 } 476 477 static DEFINE_SPINLOCK(pin_fs_lock); 478 479 int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) 480 { 481 struct vfsmount *mnt = NULL; 482 spin_lock(&pin_fs_lock); 483 if (unlikely(!*mount)) { 484 spin_unlock(&pin_fs_lock); 485 mnt = vfs_kern_mount(type, 0, type->name, NULL); 486 if (IS_ERR(mnt)) 487 return PTR_ERR(mnt); 488 spin_lock(&pin_fs_lock); 489 if (!*mount) 490 *mount = mnt; 491 } 492 mntget(*mount); 493 ++*count; 494 spin_unlock(&pin_fs_lock); 495 mntput(mnt); 496 return 0; 497 } 498 499 void simple_release_fs(struct vfsmount **mount, int *count) 500 { 501 struct vfsmount *mnt; 502 spin_lock(&pin_fs_lock); 503 mnt = *mount; 504 if (!--*count) 505 *mount = NULL; 506 spin_unlock(&pin_fs_lock); 507 mntput(mnt); 508 } 509 510 /** 511 * simple_read_from_buffer - copy data from the buffer to user space 512 * @to: the user space buffer to read to 513 * @count: the maximum number of bytes to read 514 * @ppos: the current position in the buffer 515 * @from: the buffer to read from 516 * @available: the size of the buffer 517 * 518 * The simple_read_from_buffer() function reads up to @count bytes from the 519 * buffer @from at offset @ppos into the user space address starting at @to. 520 * 521 * On success, the number of bytes read is returned and the offset @ppos is 522 * advanced by this number, or negative value is returned on error. 523 **/ 524 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, 525 const void *from, size_t available) 526 { 527 loff_t pos = *ppos; 528 if (pos < 0) 529 return -EINVAL; 530 if (pos >= available) 531 return 0; 532 if (count > available - pos) 533 count = available - pos; 534 if (copy_to_user(to, from + pos, count)) 535 return -EFAULT; 536 *ppos = pos + count; 537 return count; 538 } 539 540 /** 541 * memory_read_from_buffer - copy data from the buffer 542 * @to: the kernel space buffer to read to 543 * @count: the maximum number of bytes to read 544 * @ppos: the current position in the buffer 545 * @from: the buffer to read from 546 * @available: the size of the buffer 547 * 548 * The memory_read_from_buffer() function reads up to @count bytes from the 549 * buffer @from at offset @ppos into the kernel space address starting at @to. 550 * 551 * On success, the number of bytes read is returned and the offset @ppos is 552 * advanced by this number, or negative value is returned on error. 553 **/ 554 ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, 555 const void *from, size_t available) 556 { 557 loff_t pos = *ppos; 558 559 if (pos < 0) 560 return -EINVAL; 561 if (pos >= available) 562 return 0; 563 if (count > available - pos) 564 count = available - pos; 565 memcpy(to, from + pos, count); 566 *ppos = pos + count; 567 568 return count; 569 } 570 571 /* 572 * Transaction based IO. 573 * The file expects a single write which triggers the transaction, and then 574 * possibly a read which collects the result - which is stored in a 575 * file-local buffer. 576 */ 577 578 void simple_transaction_set(struct file *file, size_t n) 579 { 580 struct simple_transaction_argresp *ar = file->private_data; 581 582 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); 583 584 /* 585 * The barrier ensures that ar->size will really remain zero until 586 * ar->data is ready for reading. 587 */ 588 smp_mb(); 589 ar->size = n; 590 } 591 592 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) 593 { 594 struct simple_transaction_argresp *ar; 595 static DEFINE_SPINLOCK(simple_transaction_lock); 596 597 if (size > SIMPLE_TRANSACTION_LIMIT - 1) 598 return ERR_PTR(-EFBIG); 599 600 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); 601 if (!ar) 602 return ERR_PTR(-ENOMEM); 603 604 spin_lock(&simple_transaction_lock); 605 606 /* only one write allowed per open */ 607 if (file->private_data) { 608 spin_unlock(&simple_transaction_lock); 609 free_page((unsigned long)ar); 610 return ERR_PTR(-EBUSY); 611 } 612 613 file->private_data = ar; 614 615 spin_unlock(&simple_transaction_lock); 616 617 if (copy_from_user(ar->data, buf, size)) 618 return ERR_PTR(-EFAULT); 619 620 return ar->data; 621 } 622 623 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) 624 { 625 struct simple_transaction_argresp *ar = file->private_data; 626 627 if (!ar) 628 return 0; 629 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); 630 } 631 632 int simple_transaction_release(struct inode *inode, struct file *file) 633 { 634 free_page((unsigned long)file->private_data); 635 return 0; 636 } 637 638 /* Simple attribute files */ 639 640 struct simple_attr { 641 int (*get)(void *, u64 *); 642 int (*set)(void *, u64); 643 char get_buf[24]; /* enough to store a u64 and "\n\0" */ 644 char set_buf[24]; 645 void *data; 646 const char *fmt; /* format for read operation */ 647 struct mutex mutex; /* protects access to these buffers */ 648 }; 649 650 /* simple_attr_open is called by an actual attribute open file operation 651 * to set the attribute specific access operations. */ 652 int simple_attr_open(struct inode *inode, struct file *file, 653 int (*get)(void *, u64 *), int (*set)(void *, u64), 654 const char *fmt) 655 { 656 struct simple_attr *attr; 657 658 attr = kmalloc(sizeof(*attr), GFP_KERNEL); 659 if (!attr) 660 return -ENOMEM; 661 662 attr->get = get; 663 attr->set = set; 664 attr->data = inode->i_private; 665 attr->fmt = fmt; 666 mutex_init(&attr->mutex); 667 668 file->private_data = attr; 669 670 return nonseekable_open(inode, file); 671 } 672 673 int simple_attr_release(struct inode *inode, struct file *file) 674 { 675 kfree(file->private_data); 676 return 0; 677 } 678 679 /* read from the buffer that is filled with the get function */ 680 ssize_t simple_attr_read(struct file *file, char __user *buf, 681 size_t len, loff_t *ppos) 682 { 683 struct simple_attr *attr; 684 size_t size; 685 ssize_t ret; 686 687 attr = file->private_data; 688 689 if (!attr->get) 690 return -EACCES; 691 692 ret = mutex_lock_interruptible(&attr->mutex); 693 if (ret) 694 return ret; 695 696 if (*ppos) { /* continued read */ 697 size = strlen(attr->get_buf); 698 } else { /* first read */ 699 u64 val; 700 ret = attr->get(attr->data, &val); 701 if (ret) 702 goto out; 703 704 size = scnprintf(attr->get_buf, sizeof(attr->get_buf), 705 attr->fmt, (unsigned long long)val); 706 } 707 708 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); 709 out: 710 mutex_unlock(&attr->mutex); 711 return ret; 712 } 713 714 /* interpret the buffer as a number to call the set function with */ 715 ssize_t simple_attr_write(struct file *file, const char __user *buf, 716 size_t len, loff_t *ppos) 717 { 718 struct simple_attr *attr; 719 u64 val; 720 size_t size; 721 ssize_t ret; 722 723 attr = file->private_data; 724 if (!attr->set) 725 return -EACCES; 726 727 ret = mutex_lock_interruptible(&attr->mutex); 728 if (ret) 729 return ret; 730 731 ret = -EFAULT; 732 size = min(sizeof(attr->set_buf) - 1, len); 733 if (copy_from_user(attr->set_buf, buf, size)) 734 goto out; 735 736 ret = len; /* claim we got the whole input */ 737 attr->set_buf[size] = '\0'; 738 val = simple_strtol(attr->set_buf, NULL, 0); 739 attr->set(attr->data, val); 740 out: 741 mutex_unlock(&attr->mutex); 742 return ret; 743 } 744 745 /** 746 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation 747 * @sb: filesystem to do the file handle conversion on 748 * @fid: file handle to convert 749 * @fh_len: length of the file handle in bytes 750 * @fh_type: type of file handle 751 * @get_inode: filesystem callback to retrieve inode 752 * 753 * This function decodes @fid as long as it has one of the well-known 754 * Linux filehandle types and calls @get_inode on it to retrieve the 755 * inode for the object specified in the file handle. 756 */ 757 struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, 758 int fh_len, int fh_type, struct inode *(*get_inode) 759 (struct super_block *sb, u64 ino, u32 gen)) 760 { 761 struct inode *inode = NULL; 762 763 if (fh_len < 2) 764 return NULL; 765 766 switch (fh_type) { 767 case FILEID_INO32_GEN: 768 case FILEID_INO32_GEN_PARENT: 769 inode = get_inode(sb, fid->i32.ino, fid->i32.gen); 770 break; 771 } 772 773 return d_obtain_alias(inode); 774 } 775 EXPORT_SYMBOL_GPL(generic_fh_to_dentry); 776 777 /** 778 * generic_fh_to_dentry - generic helper for the fh_to_parent export operation 779 * @sb: filesystem to do the file handle conversion on 780 * @fid: file handle to convert 781 * @fh_len: length of the file handle in bytes 782 * @fh_type: type of file handle 783 * @get_inode: filesystem callback to retrieve inode 784 * 785 * This function decodes @fid as long as it has one of the well-known 786 * Linux filehandle types and calls @get_inode on it to retrieve the 787 * inode for the _parent_ object specified in the file handle if it 788 * is specified in the file handle, or NULL otherwise. 789 */ 790 struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, 791 int fh_len, int fh_type, struct inode *(*get_inode) 792 (struct super_block *sb, u64 ino, u32 gen)) 793 { 794 struct inode *inode = NULL; 795 796 if (fh_len <= 2) 797 return NULL; 798 799 switch (fh_type) { 800 case FILEID_INO32_GEN_PARENT: 801 inode = get_inode(sb, fid->i32.parent_ino, 802 (fh_len > 3 ? fid->i32.parent_gen : 0)); 803 break; 804 } 805 806 return d_obtain_alias(inode); 807 } 808 EXPORT_SYMBOL_GPL(generic_fh_to_parent); 809 810 EXPORT_SYMBOL(dcache_dir_close); 811 EXPORT_SYMBOL(dcache_dir_lseek); 812 EXPORT_SYMBOL(dcache_dir_open); 813 EXPORT_SYMBOL(dcache_readdir); 814 EXPORT_SYMBOL(generic_read_dir); 815 EXPORT_SYMBOL(get_sb_pseudo); 816 EXPORT_SYMBOL(simple_write_begin); 817 EXPORT_SYMBOL(simple_write_end); 818 EXPORT_SYMBOL(simple_dir_inode_operations); 819 EXPORT_SYMBOL(simple_dir_operations); 820 EXPORT_SYMBOL(simple_empty); 821 EXPORT_SYMBOL(d_alloc_name); 822 EXPORT_SYMBOL(simple_fill_super); 823 EXPORT_SYMBOL(simple_getattr); 824 EXPORT_SYMBOL(simple_link); 825 EXPORT_SYMBOL(simple_lookup); 826 EXPORT_SYMBOL(simple_pin_fs); 827 EXPORT_UNUSED_SYMBOL(simple_prepare_write); 828 EXPORT_SYMBOL(simple_readpage); 829 EXPORT_SYMBOL(simple_release_fs); 830 EXPORT_SYMBOL(simple_rename); 831 EXPORT_SYMBOL(simple_rmdir); 832 EXPORT_SYMBOL(simple_statfs); 833 EXPORT_SYMBOL(simple_sync_file); 834 EXPORT_SYMBOL(simple_unlink); 835 EXPORT_SYMBOL(simple_read_from_buffer); 836 EXPORT_SYMBOL(memory_read_from_buffer); 837 EXPORT_SYMBOL(simple_transaction_set); 838 EXPORT_SYMBOL(simple_transaction_get); 839 EXPORT_SYMBOL(simple_transaction_read); 840 EXPORT_SYMBOL(simple_transaction_release); 841 EXPORT_SYMBOL_GPL(simple_attr_open); 842 EXPORT_SYMBOL_GPL(simple_attr_release); 843 EXPORT_SYMBOL_GPL(simple_attr_read); 844 EXPORT_SYMBOL_GPL(simple_attr_write); 845