1 /* 2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 3 * Licensed under the GPL 4 * 5 * Ported the filesystem routines to 2.5. 6 * 2003-02-10 Petr Baudis <pasky@ucw.cz> 7 */ 8 9 #include <linux/fs.h> 10 #include <linux/magic.h> 11 #include <linux/module.h> 12 #include <linux/mm.h> 13 #include <linux/pagemap.h> 14 #include <linux/statfs.h> 15 #include <linux/slab.h> 16 #include <linux/seq_file.h> 17 #include <linux/mount.h> 18 #include <linux/namei.h> 19 #include "hostfs.h" 20 #include <init.h> 21 #include <kern.h> 22 23 struct hostfs_inode_info { 24 int fd; 25 fmode_t mode; 26 struct inode vfs_inode; 27 }; 28 29 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 30 { 31 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 32 } 33 34 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file)) 35 36 static int hostfs_d_delete(const struct dentry *dentry) 37 { 38 return 1; 39 } 40 41 static const struct dentry_operations hostfs_dentry_ops = { 42 .d_delete = hostfs_d_delete, 43 }; 44 45 /* Changed in hostfs_args before the kernel starts running */ 46 static char *root_ino = ""; 47 static int append = 0; 48 49 static const struct inode_operations hostfs_iops; 50 static const struct inode_operations hostfs_dir_iops; 51 static const struct inode_operations hostfs_link_iops; 52 53 #ifndef MODULE 54 static int __init hostfs_args(char *options, int *add) 55 { 56 char *ptr; 57 58 ptr = strchr(options, ','); 59 if (ptr != NULL) 60 *ptr++ = '\0'; 61 if (*options != '\0') 62 root_ino = options; 63 64 options = ptr; 65 while (options) { 66 ptr = strchr(options, ','); 67 if (ptr != NULL) 68 *ptr++ = '\0'; 69 if (*options != '\0') { 70 if (!strcmp(options, "append")) 71 append = 1; 72 else printf("hostfs_args - unsupported option - %s\n", 73 options); 74 } 75 options = ptr; 76 } 77 return 0; 78 } 79 80 __uml_setup("hostfs=", hostfs_args, 81 "hostfs=<root dir>,<flags>,...\n" 82 " This is used to set hostfs parameters. The root directory argument\n" 83 " is used to confine all hostfs mounts to within the specified directory\n" 84 " tree on the host. If this isn't specified, then a user inside UML can\n" 85 " mount anything on the host that's accessible to the user that's running\n" 86 " it.\n" 87 " The only flag currently supported is 'append', which specifies that all\n" 88 " files opened by hostfs will be opened in append mode.\n\n" 89 ); 90 #endif 91 92 static char *__dentry_name(struct dentry *dentry, char *name) 93 { 94 char *p = dentry_path_raw(dentry, name, PATH_MAX); 95 char *root; 96 size_t len; 97 98 root = dentry->d_sb->s_fs_info; 99 len = strlen(root); 100 if (IS_ERR(p)) { 101 __putname(name); 102 return NULL; 103 } 104 strlcpy(name, root, PATH_MAX); 105 if (len > p - name) { 106 __putname(name); 107 return NULL; 108 } 109 if (p > name + len) { 110 char *s = name + len; 111 while ((*s++ = *p++) != '\0') 112 ; 113 } 114 return name; 115 } 116 117 static char *dentry_name(struct dentry *dentry) 118 { 119 char *name = __getname(); 120 if (!name) 121 return NULL; 122 123 return __dentry_name(dentry, name); 124 } 125 126 static char *inode_name(struct inode *ino) 127 { 128 struct dentry *dentry; 129 char *name; 130 131 dentry = d_find_alias(ino); 132 if (!dentry) 133 return NULL; 134 135 name = dentry_name(dentry); 136 137 dput(dentry); 138 139 return name; 140 } 141 142 static char *follow_link(char *link) 143 { 144 int len, n; 145 char *name, *resolved, *end; 146 147 len = 64; 148 while (1) { 149 n = -ENOMEM; 150 name = kmalloc(len, GFP_KERNEL); 151 if (name == NULL) 152 goto out; 153 154 n = hostfs_do_readlink(link, name, len); 155 if (n < len) 156 break; 157 len *= 2; 158 kfree(name); 159 } 160 if (n < 0) 161 goto out_free; 162 163 if (*name == '/') 164 return name; 165 166 end = strrchr(link, '/'); 167 if (end == NULL) 168 return name; 169 170 *(end + 1) = '\0'; 171 len = strlen(link) + strlen(name) + 1; 172 173 resolved = kmalloc(len, GFP_KERNEL); 174 if (resolved == NULL) { 175 n = -ENOMEM; 176 goto out_free; 177 } 178 179 sprintf(resolved, "%s%s", link, name); 180 kfree(name); 181 kfree(link); 182 return resolved; 183 184 out_free: 185 kfree(name); 186 out: 187 return ERR_PTR(n); 188 } 189 190 static struct inode *hostfs_iget(struct super_block *sb) 191 { 192 struct inode *inode = new_inode(sb); 193 if (!inode) 194 return ERR_PTR(-ENOMEM); 195 return inode; 196 } 197 198 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 199 { 200 /* 201 * do_statfs uses struct statfs64 internally, but the linux kernel 202 * struct statfs still has 32-bit versions for most of these fields, 203 * so we convert them here 204 */ 205 int err; 206 long long f_blocks; 207 long long f_bfree; 208 long long f_bavail; 209 long long f_files; 210 long long f_ffree; 211 212 err = do_statfs(dentry->d_sb->s_fs_info, 213 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 214 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 215 &sf->f_namelen); 216 if (err) 217 return err; 218 sf->f_blocks = f_blocks; 219 sf->f_bfree = f_bfree; 220 sf->f_bavail = f_bavail; 221 sf->f_files = f_files; 222 sf->f_ffree = f_ffree; 223 sf->f_type = HOSTFS_SUPER_MAGIC; 224 return 0; 225 } 226 227 static struct inode *hostfs_alloc_inode(struct super_block *sb) 228 { 229 struct hostfs_inode_info *hi; 230 231 hi = kmalloc(sizeof(*hi), GFP_KERNEL); 232 if (hi == NULL) 233 return NULL; 234 hi->fd = -1; 235 hi->mode = 0; 236 inode_init_once(&hi->vfs_inode); 237 return &hi->vfs_inode; 238 } 239 240 static void hostfs_evict_inode(struct inode *inode) 241 { 242 truncate_inode_pages(&inode->i_data, 0); 243 clear_inode(inode); 244 if (HOSTFS_I(inode)->fd != -1) { 245 close_file(&HOSTFS_I(inode)->fd); 246 HOSTFS_I(inode)->fd = -1; 247 } 248 } 249 250 static void hostfs_i_callback(struct rcu_head *head) 251 { 252 struct inode *inode = container_of(head, struct inode, i_rcu); 253 kfree(HOSTFS_I(inode)); 254 } 255 256 static void hostfs_destroy_inode(struct inode *inode) 257 { 258 call_rcu(&inode->i_rcu, hostfs_i_callback); 259 } 260 261 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 262 { 263 const char *root_path = root->d_sb->s_fs_info; 264 size_t offset = strlen(root_ino) + 1; 265 266 if (strlen(root_path) > offset) 267 seq_printf(seq, ",%s", root_path + offset); 268 269 return 0; 270 } 271 272 static const struct super_operations hostfs_sbops = { 273 .alloc_inode = hostfs_alloc_inode, 274 .destroy_inode = hostfs_destroy_inode, 275 .evict_inode = hostfs_evict_inode, 276 .statfs = hostfs_statfs, 277 .show_options = hostfs_show_options, 278 }; 279 280 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir) 281 { 282 void *dir; 283 char *name; 284 unsigned long long next, ino; 285 int error, len; 286 unsigned int type; 287 288 name = dentry_name(file->f_path.dentry); 289 if (name == NULL) 290 return -ENOMEM; 291 dir = open_dir(name, &error); 292 __putname(name); 293 if (dir == NULL) 294 return -error; 295 next = file->f_pos; 296 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 297 error = (*filldir)(ent, name, len, file->f_pos, 298 ino, type); 299 if (error) break; 300 file->f_pos = next; 301 } 302 close_dir(dir); 303 return 0; 304 } 305 306 int hostfs_file_open(struct inode *ino, struct file *file) 307 { 308 static DEFINE_MUTEX(open_mutex); 309 char *name; 310 fmode_t mode = 0; 311 int err; 312 int r = 0, w = 0, fd; 313 314 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 315 if ((mode & HOSTFS_I(ino)->mode) == mode) 316 return 0; 317 318 mode |= HOSTFS_I(ino)->mode; 319 320 retry: 321 if (mode & FMODE_READ) 322 r = 1; 323 if (mode & FMODE_WRITE) 324 w = 1; 325 if (w) 326 r = 1; 327 328 name = dentry_name(file->f_path.dentry); 329 if (name == NULL) 330 return -ENOMEM; 331 332 fd = open_file(name, r, w, append); 333 __putname(name); 334 if (fd < 0) 335 return fd; 336 337 mutex_lock(&open_mutex); 338 /* somebody else had handled it first? */ 339 if ((mode & HOSTFS_I(ino)->mode) == mode) { 340 mutex_unlock(&open_mutex); 341 return 0; 342 } 343 if ((mode | HOSTFS_I(ino)->mode) != mode) { 344 mode |= HOSTFS_I(ino)->mode; 345 mutex_unlock(&open_mutex); 346 close_file(&fd); 347 goto retry; 348 } 349 if (HOSTFS_I(ino)->fd == -1) { 350 HOSTFS_I(ino)->fd = fd; 351 } else { 352 err = replace_file(fd, HOSTFS_I(ino)->fd); 353 close_file(&fd); 354 if (err < 0) { 355 mutex_unlock(&open_mutex); 356 return err; 357 } 358 } 359 HOSTFS_I(ino)->mode = mode; 360 mutex_unlock(&open_mutex); 361 362 return 0; 363 } 364 365 int hostfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 366 { 367 struct inode *inode = file->f_mapping->host; 368 int ret; 369 370 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 371 if (ret) 372 return ret; 373 374 mutex_lock(&inode->i_mutex); 375 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 376 mutex_unlock(&inode->i_mutex); 377 378 return ret; 379 } 380 381 static const struct file_operations hostfs_file_fops = { 382 .llseek = generic_file_llseek, 383 .read = do_sync_read, 384 .splice_read = generic_file_splice_read, 385 .aio_read = generic_file_aio_read, 386 .aio_write = generic_file_aio_write, 387 .write = do_sync_write, 388 .mmap = generic_file_mmap, 389 .open = hostfs_file_open, 390 .release = NULL, 391 .fsync = hostfs_fsync, 392 }; 393 394 static const struct file_operations hostfs_dir_fops = { 395 .llseek = generic_file_llseek, 396 .readdir = hostfs_readdir, 397 .read = generic_read_dir, 398 }; 399 400 int hostfs_writepage(struct page *page, struct writeback_control *wbc) 401 { 402 struct address_space *mapping = page->mapping; 403 struct inode *inode = mapping->host; 404 char *buffer; 405 unsigned long long base; 406 int count = PAGE_CACHE_SIZE; 407 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 408 int err; 409 410 if (page->index >= end_index) 411 count = inode->i_size & (PAGE_CACHE_SIZE-1); 412 413 buffer = kmap(page); 414 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; 415 416 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 417 if (err != count) { 418 ClearPageUptodate(page); 419 goto out; 420 } 421 422 if (base > inode->i_size) 423 inode->i_size = base; 424 425 if (PageError(page)) 426 ClearPageError(page); 427 err = 0; 428 429 out: 430 kunmap(page); 431 432 unlock_page(page); 433 return err; 434 } 435 436 int hostfs_readpage(struct file *file, struct page *page) 437 { 438 char *buffer; 439 long long start; 440 int err = 0; 441 442 start = (long long) page->index << PAGE_CACHE_SHIFT; 443 buffer = kmap(page); 444 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 445 PAGE_CACHE_SIZE); 446 if (err < 0) 447 goto out; 448 449 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); 450 451 flush_dcache_page(page); 452 SetPageUptodate(page); 453 if (PageError(page)) ClearPageError(page); 454 err = 0; 455 out: 456 kunmap(page); 457 unlock_page(page); 458 return err; 459 } 460 461 int hostfs_write_begin(struct file *file, struct address_space *mapping, 462 loff_t pos, unsigned len, unsigned flags, 463 struct page **pagep, void **fsdata) 464 { 465 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 466 467 *pagep = grab_cache_page_write_begin(mapping, index, flags); 468 if (!*pagep) 469 return -ENOMEM; 470 return 0; 471 } 472 473 int hostfs_write_end(struct file *file, struct address_space *mapping, 474 loff_t pos, unsigned len, unsigned copied, 475 struct page *page, void *fsdata) 476 { 477 struct inode *inode = mapping->host; 478 void *buffer; 479 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 480 int err; 481 482 buffer = kmap(page); 483 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 484 kunmap(page); 485 486 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE) 487 SetPageUptodate(page); 488 489 /* 490 * If err > 0, write_file has added err to pos, so we are comparing 491 * i_size against the last byte written. 492 */ 493 if (err > 0 && (pos > inode->i_size)) 494 inode->i_size = pos; 495 unlock_page(page); 496 page_cache_release(page); 497 498 return err; 499 } 500 501 static const struct address_space_operations hostfs_aops = { 502 .writepage = hostfs_writepage, 503 .readpage = hostfs_readpage, 504 .set_page_dirty = __set_page_dirty_nobuffers, 505 .write_begin = hostfs_write_begin, 506 .write_end = hostfs_write_end, 507 }; 508 509 static int read_name(struct inode *ino, char *name) 510 { 511 dev_t rdev; 512 struct hostfs_stat st; 513 int err = stat_file(name, &st, -1); 514 if (err) 515 return err; 516 517 /* Reencode maj and min with the kernel encoding.*/ 518 rdev = MKDEV(st.maj, st.min); 519 520 switch (st.mode & S_IFMT) { 521 case S_IFLNK: 522 ino->i_op = &hostfs_link_iops; 523 break; 524 case S_IFDIR: 525 ino->i_op = &hostfs_dir_iops; 526 ino->i_fop = &hostfs_dir_fops; 527 break; 528 case S_IFCHR: 529 case S_IFBLK: 530 case S_IFIFO: 531 case S_IFSOCK: 532 init_special_inode(ino, st.mode & S_IFMT, rdev); 533 ino->i_op = &hostfs_iops; 534 break; 535 536 default: 537 ino->i_op = &hostfs_iops; 538 ino->i_fop = &hostfs_file_fops; 539 ino->i_mapping->a_ops = &hostfs_aops; 540 } 541 542 ino->i_ino = st.ino; 543 ino->i_mode = st.mode; 544 set_nlink(ino, st.nlink); 545 i_uid_write(ino, st.uid); 546 i_gid_write(ino, st.gid); 547 ino->i_atime = st.atime; 548 ino->i_mtime = st.mtime; 549 ino->i_ctime = st.ctime; 550 ino->i_size = st.size; 551 ino->i_blocks = st.blocks; 552 return 0; 553 } 554 555 int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 556 bool excl) 557 { 558 struct inode *inode; 559 char *name; 560 int error, fd; 561 562 inode = hostfs_iget(dir->i_sb); 563 if (IS_ERR(inode)) { 564 error = PTR_ERR(inode); 565 goto out; 566 } 567 568 error = -ENOMEM; 569 name = dentry_name(dentry); 570 if (name == NULL) 571 goto out_put; 572 573 fd = file_create(name, 574 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, 575 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, 576 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); 577 if (fd < 0) 578 error = fd; 579 else 580 error = read_name(inode, name); 581 582 __putname(name); 583 if (error) 584 goto out_put; 585 586 HOSTFS_I(inode)->fd = fd; 587 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 588 d_instantiate(dentry, inode); 589 return 0; 590 591 out_put: 592 iput(inode); 593 out: 594 return error; 595 } 596 597 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 598 unsigned int flags) 599 { 600 struct inode *inode; 601 char *name; 602 int err; 603 604 inode = hostfs_iget(ino->i_sb); 605 if (IS_ERR(inode)) { 606 err = PTR_ERR(inode); 607 goto out; 608 } 609 610 err = -ENOMEM; 611 name = dentry_name(dentry); 612 if (name == NULL) 613 goto out_put; 614 615 err = read_name(inode, name); 616 617 __putname(name); 618 if (err == -ENOENT) { 619 iput(inode); 620 inode = NULL; 621 } 622 else if (err) 623 goto out_put; 624 625 d_add(dentry, inode); 626 return NULL; 627 628 out_put: 629 iput(inode); 630 out: 631 return ERR_PTR(err); 632 } 633 634 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from) 635 { 636 char *from_name, *to_name; 637 int err; 638 639 if ((from_name = dentry_name(from)) == NULL) 640 return -ENOMEM; 641 to_name = dentry_name(to); 642 if (to_name == NULL) { 643 __putname(from_name); 644 return -ENOMEM; 645 } 646 err = link_file(to_name, from_name); 647 __putname(from_name); 648 __putname(to_name); 649 return err; 650 } 651 652 int hostfs_unlink(struct inode *ino, struct dentry *dentry) 653 { 654 char *file; 655 int err; 656 657 if (append) 658 return -EPERM; 659 660 if ((file = dentry_name(dentry)) == NULL) 661 return -ENOMEM; 662 663 err = unlink_file(file); 664 __putname(file); 665 return err; 666 } 667 668 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to) 669 { 670 char *file; 671 int err; 672 673 if ((file = dentry_name(dentry)) == NULL) 674 return -ENOMEM; 675 err = make_symlink(file, to); 676 __putname(file); 677 return err; 678 } 679 680 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 681 { 682 char *file; 683 int err; 684 685 if ((file = dentry_name(dentry)) == NULL) 686 return -ENOMEM; 687 err = do_mkdir(file, mode); 688 __putname(file); 689 return err; 690 } 691 692 int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 693 { 694 char *file; 695 int err; 696 697 if ((file = dentry_name(dentry)) == NULL) 698 return -ENOMEM; 699 err = do_rmdir(file); 700 __putname(file); 701 return err; 702 } 703 704 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 705 { 706 struct inode *inode; 707 char *name; 708 int err; 709 710 inode = hostfs_iget(dir->i_sb); 711 if (IS_ERR(inode)) { 712 err = PTR_ERR(inode); 713 goto out; 714 } 715 716 err = -ENOMEM; 717 name = dentry_name(dentry); 718 if (name == NULL) 719 goto out_put; 720 721 init_special_inode(inode, mode, dev); 722 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 723 if (!err) 724 goto out_free; 725 726 err = read_name(inode, name); 727 __putname(name); 728 if (err) 729 goto out_put; 730 if (err) 731 goto out_put; 732 733 d_instantiate(dentry, inode); 734 return 0; 735 736 out_free: 737 __putname(name); 738 out_put: 739 iput(inode); 740 out: 741 return err; 742 } 743 744 int hostfs_rename(struct inode *from_ino, struct dentry *from, 745 struct inode *to_ino, struct dentry *to) 746 { 747 char *from_name, *to_name; 748 int err; 749 750 if ((from_name = dentry_name(from)) == NULL) 751 return -ENOMEM; 752 if ((to_name = dentry_name(to)) == NULL) { 753 __putname(from_name); 754 return -ENOMEM; 755 } 756 err = rename_file(from_name, to_name); 757 __putname(from_name); 758 __putname(to_name); 759 return err; 760 } 761 762 int hostfs_permission(struct inode *ino, int desired) 763 { 764 char *name; 765 int r = 0, w = 0, x = 0, err; 766 767 if (desired & MAY_NOT_BLOCK) 768 return -ECHILD; 769 770 if (desired & MAY_READ) r = 1; 771 if (desired & MAY_WRITE) w = 1; 772 if (desired & MAY_EXEC) x = 1; 773 name = inode_name(ino); 774 if (name == NULL) 775 return -ENOMEM; 776 777 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 778 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 779 err = 0; 780 else 781 err = access_file(name, r, w, x); 782 __putname(name); 783 if (!err) 784 err = generic_permission(ino, desired); 785 return err; 786 } 787 788 int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 789 { 790 struct inode *inode = dentry->d_inode; 791 struct hostfs_iattr attrs; 792 char *name; 793 int err; 794 795 int fd = HOSTFS_I(inode)->fd; 796 797 err = inode_change_ok(inode, attr); 798 if (err) 799 return err; 800 801 if (append) 802 attr->ia_valid &= ~ATTR_SIZE; 803 804 attrs.ia_valid = 0; 805 if (attr->ia_valid & ATTR_MODE) { 806 attrs.ia_valid |= HOSTFS_ATTR_MODE; 807 attrs.ia_mode = attr->ia_mode; 808 } 809 if (attr->ia_valid & ATTR_UID) { 810 attrs.ia_valid |= HOSTFS_ATTR_UID; 811 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 812 } 813 if (attr->ia_valid & ATTR_GID) { 814 attrs.ia_valid |= HOSTFS_ATTR_GID; 815 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 816 } 817 if (attr->ia_valid & ATTR_SIZE) { 818 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 819 attrs.ia_size = attr->ia_size; 820 } 821 if (attr->ia_valid & ATTR_ATIME) { 822 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 823 attrs.ia_atime = attr->ia_atime; 824 } 825 if (attr->ia_valid & ATTR_MTIME) { 826 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 827 attrs.ia_mtime = attr->ia_mtime; 828 } 829 if (attr->ia_valid & ATTR_CTIME) { 830 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 831 attrs.ia_ctime = attr->ia_ctime; 832 } 833 if (attr->ia_valid & ATTR_ATIME_SET) { 834 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 835 } 836 if (attr->ia_valid & ATTR_MTIME_SET) { 837 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 838 } 839 name = dentry_name(dentry); 840 if (name == NULL) 841 return -ENOMEM; 842 err = set_attr(name, &attrs, fd); 843 __putname(name); 844 if (err) 845 return err; 846 847 if ((attr->ia_valid & ATTR_SIZE) && 848 attr->ia_size != i_size_read(inode)) 849 truncate_setsize(inode, attr->ia_size); 850 851 setattr_copy(inode, attr); 852 mark_inode_dirty(inode); 853 return 0; 854 } 855 856 static const struct inode_operations hostfs_iops = { 857 .permission = hostfs_permission, 858 .setattr = hostfs_setattr, 859 }; 860 861 static const struct inode_operations hostfs_dir_iops = { 862 .create = hostfs_create, 863 .lookup = hostfs_lookup, 864 .link = hostfs_link, 865 .unlink = hostfs_unlink, 866 .symlink = hostfs_symlink, 867 .mkdir = hostfs_mkdir, 868 .rmdir = hostfs_rmdir, 869 .mknod = hostfs_mknod, 870 .rename = hostfs_rename, 871 .permission = hostfs_permission, 872 .setattr = hostfs_setattr, 873 }; 874 875 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) 876 { 877 char *link = __getname(); 878 if (link) { 879 char *path = dentry_name(dentry); 880 int err = -ENOMEM; 881 if (path) { 882 err = hostfs_do_readlink(path, link, PATH_MAX); 883 if (err == PATH_MAX) 884 err = -E2BIG; 885 __putname(path); 886 } 887 if (err < 0) { 888 __putname(link); 889 link = ERR_PTR(err); 890 } 891 } else { 892 link = ERR_PTR(-ENOMEM); 893 } 894 895 nd_set_link(nd, link); 896 return NULL; 897 } 898 899 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 900 { 901 char *s = nd_get_link(nd); 902 if (!IS_ERR(s)) 903 __putname(s); 904 } 905 906 static const struct inode_operations hostfs_link_iops = { 907 .readlink = generic_readlink, 908 .follow_link = hostfs_follow_link, 909 .put_link = hostfs_put_link, 910 }; 911 912 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 913 { 914 struct inode *root_inode; 915 char *host_root_path, *req_root = d; 916 int err; 917 918 sb->s_blocksize = 1024; 919 sb->s_blocksize_bits = 10; 920 sb->s_magic = HOSTFS_SUPER_MAGIC; 921 sb->s_op = &hostfs_sbops; 922 sb->s_d_op = &hostfs_dentry_ops; 923 sb->s_maxbytes = MAX_LFS_FILESIZE; 924 925 /* NULL is printed as <NULL> by sprintf: avoid that. */ 926 if (req_root == NULL) 927 req_root = ""; 928 929 err = -ENOMEM; 930 sb->s_fs_info = host_root_path = 931 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 932 if (host_root_path == NULL) 933 goto out; 934 935 sprintf(host_root_path, "%s/%s", root_ino, req_root); 936 937 root_inode = new_inode(sb); 938 if (!root_inode) 939 goto out; 940 941 err = read_name(root_inode, host_root_path); 942 if (err) 943 goto out_put; 944 945 if (S_ISLNK(root_inode->i_mode)) { 946 char *name = follow_link(host_root_path); 947 if (IS_ERR(name)) 948 err = PTR_ERR(name); 949 else 950 err = read_name(root_inode, name); 951 kfree(name); 952 if (err) 953 goto out_put; 954 } 955 956 err = -ENOMEM; 957 sb->s_root = d_make_root(root_inode); 958 if (sb->s_root == NULL) 959 goto out; 960 961 return 0; 962 963 out_put: 964 iput(root_inode); 965 out: 966 return err; 967 } 968 969 static struct dentry *hostfs_read_sb(struct file_system_type *type, 970 int flags, const char *dev_name, 971 void *data) 972 { 973 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 974 } 975 976 static void hostfs_kill_sb(struct super_block *s) 977 { 978 kill_anon_super(s); 979 kfree(s->s_fs_info); 980 } 981 982 static struct file_system_type hostfs_type = { 983 .owner = THIS_MODULE, 984 .name = "hostfs", 985 .mount = hostfs_read_sb, 986 .kill_sb = hostfs_kill_sb, 987 .fs_flags = 0, 988 }; 989 MODULE_ALIAS_FS("hostfs"); 990 991 static int __init init_hostfs(void) 992 { 993 return register_filesystem(&hostfs_type); 994 } 995 996 static void __exit exit_hostfs(void) 997 { 998 unregister_filesystem(&hostfs_type); 999 } 1000 1001 module_init(init_hostfs) 1002 module_exit(exit_hostfs) 1003 MODULE_LICENSE("GPL"); 1004