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, struct dir_context *ctx) 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 = ctx->pos; 296 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 297 if (!dir_emit(ctx, name, len, ino, type)) 298 break; 299 ctx->pos = next; 300 } 301 close_dir(dir); 302 return 0; 303 } 304 305 int hostfs_file_open(struct inode *ino, struct file *file) 306 { 307 static DEFINE_MUTEX(open_mutex); 308 char *name; 309 fmode_t mode = 0; 310 int err; 311 int r = 0, w = 0, fd; 312 313 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 314 if ((mode & HOSTFS_I(ino)->mode) == mode) 315 return 0; 316 317 mode |= HOSTFS_I(ino)->mode; 318 319 retry: 320 if (mode & FMODE_READ) 321 r = 1; 322 if (mode & FMODE_WRITE) 323 w = 1; 324 if (w) 325 r = 1; 326 327 name = dentry_name(file->f_path.dentry); 328 if (name == NULL) 329 return -ENOMEM; 330 331 fd = open_file(name, r, w, append); 332 __putname(name); 333 if (fd < 0) 334 return fd; 335 336 mutex_lock(&open_mutex); 337 /* somebody else had handled it first? */ 338 if ((mode & HOSTFS_I(ino)->mode) == mode) { 339 mutex_unlock(&open_mutex); 340 return 0; 341 } 342 if ((mode | HOSTFS_I(ino)->mode) != mode) { 343 mode |= HOSTFS_I(ino)->mode; 344 mutex_unlock(&open_mutex); 345 close_file(&fd); 346 goto retry; 347 } 348 if (HOSTFS_I(ino)->fd == -1) { 349 HOSTFS_I(ino)->fd = fd; 350 } else { 351 err = replace_file(fd, HOSTFS_I(ino)->fd); 352 close_file(&fd); 353 if (err < 0) { 354 mutex_unlock(&open_mutex); 355 return err; 356 } 357 } 358 HOSTFS_I(ino)->mode = mode; 359 mutex_unlock(&open_mutex); 360 361 return 0; 362 } 363 364 int hostfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 365 { 366 struct inode *inode = file->f_mapping->host; 367 int ret; 368 369 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 370 if (ret) 371 return ret; 372 373 mutex_lock(&inode->i_mutex); 374 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 375 mutex_unlock(&inode->i_mutex); 376 377 return ret; 378 } 379 380 static const struct file_operations hostfs_file_fops = { 381 .llseek = generic_file_llseek, 382 .read = do_sync_read, 383 .splice_read = generic_file_splice_read, 384 .aio_read = generic_file_aio_read, 385 .aio_write = generic_file_aio_write, 386 .write = do_sync_write, 387 .mmap = generic_file_mmap, 388 .open = hostfs_file_open, 389 .release = NULL, 390 .fsync = hostfs_fsync, 391 }; 392 393 static const struct file_operations hostfs_dir_fops = { 394 .llseek = generic_file_llseek, 395 .iterate = hostfs_readdir, 396 .read = generic_read_dir, 397 }; 398 399 int hostfs_writepage(struct page *page, struct writeback_control *wbc) 400 { 401 struct address_space *mapping = page->mapping; 402 struct inode *inode = mapping->host; 403 char *buffer; 404 unsigned long long base; 405 int count = PAGE_CACHE_SIZE; 406 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 407 int err; 408 409 if (page->index >= end_index) 410 count = inode->i_size & (PAGE_CACHE_SIZE-1); 411 412 buffer = kmap(page); 413 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; 414 415 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 416 if (err != count) { 417 ClearPageUptodate(page); 418 goto out; 419 } 420 421 if (base > inode->i_size) 422 inode->i_size = base; 423 424 if (PageError(page)) 425 ClearPageError(page); 426 err = 0; 427 428 out: 429 kunmap(page); 430 431 unlock_page(page); 432 return err; 433 } 434 435 int hostfs_readpage(struct file *file, struct page *page) 436 { 437 char *buffer; 438 long long start; 439 int err = 0; 440 441 start = (long long) page->index << PAGE_CACHE_SHIFT; 442 buffer = kmap(page); 443 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 444 PAGE_CACHE_SIZE); 445 if (err < 0) 446 goto out; 447 448 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); 449 450 flush_dcache_page(page); 451 SetPageUptodate(page); 452 if (PageError(page)) ClearPageError(page); 453 err = 0; 454 out: 455 kunmap(page); 456 unlock_page(page); 457 return err; 458 } 459 460 int hostfs_write_begin(struct file *file, struct address_space *mapping, 461 loff_t pos, unsigned len, unsigned flags, 462 struct page **pagep, void **fsdata) 463 { 464 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 465 466 *pagep = grab_cache_page_write_begin(mapping, index, flags); 467 if (!*pagep) 468 return -ENOMEM; 469 return 0; 470 } 471 472 int hostfs_write_end(struct file *file, struct address_space *mapping, 473 loff_t pos, unsigned len, unsigned copied, 474 struct page *page, void *fsdata) 475 { 476 struct inode *inode = mapping->host; 477 void *buffer; 478 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 479 int err; 480 481 buffer = kmap(page); 482 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 483 kunmap(page); 484 485 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE) 486 SetPageUptodate(page); 487 488 /* 489 * If err > 0, write_file has added err to pos, so we are comparing 490 * i_size against the last byte written. 491 */ 492 if (err > 0 && (pos > inode->i_size)) 493 inode->i_size = pos; 494 unlock_page(page); 495 page_cache_release(page); 496 497 return err; 498 } 499 500 static const struct address_space_operations hostfs_aops = { 501 .writepage = hostfs_writepage, 502 .readpage = hostfs_readpage, 503 .set_page_dirty = __set_page_dirty_nobuffers, 504 .write_begin = hostfs_write_begin, 505 .write_end = hostfs_write_end, 506 }; 507 508 static int read_name(struct inode *ino, char *name) 509 { 510 dev_t rdev; 511 struct hostfs_stat st; 512 int err = stat_file(name, &st, -1); 513 if (err) 514 return err; 515 516 /* Reencode maj and min with the kernel encoding.*/ 517 rdev = MKDEV(st.maj, st.min); 518 519 switch (st.mode & S_IFMT) { 520 case S_IFLNK: 521 ino->i_op = &hostfs_link_iops; 522 break; 523 case S_IFDIR: 524 ino->i_op = &hostfs_dir_iops; 525 ino->i_fop = &hostfs_dir_fops; 526 break; 527 case S_IFCHR: 528 case S_IFBLK: 529 case S_IFIFO: 530 case S_IFSOCK: 531 init_special_inode(ino, st.mode & S_IFMT, rdev); 532 ino->i_op = &hostfs_iops; 533 break; 534 535 default: 536 ino->i_op = &hostfs_iops; 537 ino->i_fop = &hostfs_file_fops; 538 ino->i_mapping->a_ops = &hostfs_aops; 539 } 540 541 ino->i_ino = st.ino; 542 ino->i_mode = st.mode; 543 set_nlink(ino, st.nlink); 544 i_uid_write(ino, st.uid); 545 i_gid_write(ino, st.gid); 546 ino->i_atime = st.atime; 547 ino->i_mtime = st.mtime; 548 ino->i_ctime = st.ctime; 549 ino->i_size = st.size; 550 ino->i_blocks = st.blocks; 551 return 0; 552 } 553 554 int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 555 bool excl) 556 { 557 struct inode *inode; 558 char *name; 559 int error, fd; 560 561 inode = hostfs_iget(dir->i_sb); 562 if (IS_ERR(inode)) { 563 error = PTR_ERR(inode); 564 goto out; 565 } 566 567 error = -ENOMEM; 568 name = dentry_name(dentry); 569 if (name == NULL) 570 goto out_put; 571 572 fd = file_create(name, 573 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, 574 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, 575 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); 576 if (fd < 0) 577 error = fd; 578 else 579 error = read_name(inode, name); 580 581 __putname(name); 582 if (error) 583 goto out_put; 584 585 HOSTFS_I(inode)->fd = fd; 586 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 587 d_instantiate(dentry, inode); 588 return 0; 589 590 out_put: 591 iput(inode); 592 out: 593 return error; 594 } 595 596 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 597 unsigned int flags) 598 { 599 struct inode *inode; 600 char *name; 601 int err; 602 603 inode = hostfs_iget(ino->i_sb); 604 if (IS_ERR(inode)) { 605 err = PTR_ERR(inode); 606 goto out; 607 } 608 609 err = -ENOMEM; 610 name = dentry_name(dentry); 611 if (name == NULL) 612 goto out_put; 613 614 err = read_name(inode, name); 615 616 __putname(name); 617 if (err == -ENOENT) { 618 iput(inode); 619 inode = NULL; 620 } 621 else if (err) 622 goto out_put; 623 624 d_add(dentry, inode); 625 return NULL; 626 627 out_put: 628 iput(inode); 629 out: 630 return ERR_PTR(err); 631 } 632 633 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from) 634 { 635 char *from_name, *to_name; 636 int err; 637 638 if ((from_name = dentry_name(from)) == NULL) 639 return -ENOMEM; 640 to_name = dentry_name(to); 641 if (to_name == NULL) { 642 __putname(from_name); 643 return -ENOMEM; 644 } 645 err = link_file(to_name, from_name); 646 __putname(from_name); 647 __putname(to_name); 648 return err; 649 } 650 651 int hostfs_unlink(struct inode *ino, struct dentry *dentry) 652 { 653 char *file; 654 int err; 655 656 if (append) 657 return -EPERM; 658 659 if ((file = dentry_name(dentry)) == NULL) 660 return -ENOMEM; 661 662 err = unlink_file(file); 663 __putname(file); 664 return err; 665 } 666 667 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to) 668 { 669 char *file; 670 int err; 671 672 if ((file = dentry_name(dentry)) == NULL) 673 return -ENOMEM; 674 err = make_symlink(file, to); 675 __putname(file); 676 return err; 677 } 678 679 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 680 { 681 char *file; 682 int err; 683 684 if ((file = dentry_name(dentry)) == NULL) 685 return -ENOMEM; 686 err = do_mkdir(file, mode); 687 __putname(file); 688 return err; 689 } 690 691 int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 692 { 693 char *file; 694 int err; 695 696 if ((file = dentry_name(dentry)) == NULL) 697 return -ENOMEM; 698 err = do_rmdir(file); 699 __putname(file); 700 return err; 701 } 702 703 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 704 { 705 struct inode *inode; 706 char *name; 707 int err; 708 709 inode = hostfs_iget(dir->i_sb); 710 if (IS_ERR(inode)) { 711 err = PTR_ERR(inode); 712 goto out; 713 } 714 715 err = -ENOMEM; 716 name = dentry_name(dentry); 717 if (name == NULL) 718 goto out_put; 719 720 init_special_inode(inode, mode, dev); 721 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 722 if (!err) 723 goto out_free; 724 725 err = read_name(inode, name); 726 __putname(name); 727 if (err) 728 goto out_put; 729 if (err) 730 goto out_put; 731 732 d_instantiate(dentry, inode); 733 return 0; 734 735 out_free: 736 __putname(name); 737 out_put: 738 iput(inode); 739 out: 740 return err; 741 } 742 743 int hostfs_rename(struct inode *from_ino, struct dentry *from, 744 struct inode *to_ino, struct dentry *to) 745 { 746 char *from_name, *to_name; 747 int err; 748 749 if ((from_name = dentry_name(from)) == NULL) 750 return -ENOMEM; 751 if ((to_name = dentry_name(to)) == NULL) { 752 __putname(from_name); 753 return -ENOMEM; 754 } 755 err = rename_file(from_name, to_name); 756 __putname(from_name); 757 __putname(to_name); 758 return err; 759 } 760 761 int hostfs_permission(struct inode *ino, int desired) 762 { 763 char *name; 764 int r = 0, w = 0, x = 0, err; 765 766 if (desired & MAY_NOT_BLOCK) 767 return -ECHILD; 768 769 if (desired & MAY_READ) r = 1; 770 if (desired & MAY_WRITE) w = 1; 771 if (desired & MAY_EXEC) x = 1; 772 name = inode_name(ino); 773 if (name == NULL) 774 return -ENOMEM; 775 776 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 777 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 778 err = 0; 779 else 780 err = access_file(name, r, w, x); 781 __putname(name); 782 if (!err) 783 err = generic_permission(ino, desired); 784 return err; 785 } 786 787 int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 788 { 789 struct inode *inode = dentry->d_inode; 790 struct hostfs_iattr attrs; 791 char *name; 792 int err; 793 794 int fd = HOSTFS_I(inode)->fd; 795 796 err = inode_change_ok(inode, attr); 797 if (err) 798 return err; 799 800 if (append) 801 attr->ia_valid &= ~ATTR_SIZE; 802 803 attrs.ia_valid = 0; 804 if (attr->ia_valid & ATTR_MODE) { 805 attrs.ia_valid |= HOSTFS_ATTR_MODE; 806 attrs.ia_mode = attr->ia_mode; 807 } 808 if (attr->ia_valid & ATTR_UID) { 809 attrs.ia_valid |= HOSTFS_ATTR_UID; 810 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 811 } 812 if (attr->ia_valid & ATTR_GID) { 813 attrs.ia_valid |= HOSTFS_ATTR_GID; 814 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 815 } 816 if (attr->ia_valid & ATTR_SIZE) { 817 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 818 attrs.ia_size = attr->ia_size; 819 } 820 if (attr->ia_valid & ATTR_ATIME) { 821 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 822 attrs.ia_atime = attr->ia_atime; 823 } 824 if (attr->ia_valid & ATTR_MTIME) { 825 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 826 attrs.ia_mtime = attr->ia_mtime; 827 } 828 if (attr->ia_valid & ATTR_CTIME) { 829 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 830 attrs.ia_ctime = attr->ia_ctime; 831 } 832 if (attr->ia_valid & ATTR_ATIME_SET) { 833 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 834 } 835 if (attr->ia_valid & ATTR_MTIME_SET) { 836 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 837 } 838 name = dentry_name(dentry); 839 if (name == NULL) 840 return -ENOMEM; 841 err = set_attr(name, &attrs, fd); 842 __putname(name); 843 if (err) 844 return err; 845 846 if ((attr->ia_valid & ATTR_SIZE) && 847 attr->ia_size != i_size_read(inode)) 848 truncate_setsize(inode, attr->ia_size); 849 850 setattr_copy(inode, attr); 851 mark_inode_dirty(inode); 852 return 0; 853 } 854 855 static const struct inode_operations hostfs_iops = { 856 .permission = hostfs_permission, 857 .setattr = hostfs_setattr, 858 }; 859 860 static const struct inode_operations hostfs_dir_iops = { 861 .create = hostfs_create, 862 .lookup = hostfs_lookup, 863 .link = hostfs_link, 864 .unlink = hostfs_unlink, 865 .symlink = hostfs_symlink, 866 .mkdir = hostfs_mkdir, 867 .rmdir = hostfs_rmdir, 868 .mknod = hostfs_mknod, 869 .rename = hostfs_rename, 870 .permission = hostfs_permission, 871 .setattr = hostfs_setattr, 872 }; 873 874 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) 875 { 876 char *link = __getname(); 877 if (link) { 878 char *path = dentry_name(dentry); 879 int err = -ENOMEM; 880 if (path) { 881 err = hostfs_do_readlink(path, link, PATH_MAX); 882 if (err == PATH_MAX) 883 err = -E2BIG; 884 __putname(path); 885 } 886 if (err < 0) { 887 __putname(link); 888 link = ERR_PTR(err); 889 } 890 } else { 891 link = ERR_PTR(-ENOMEM); 892 } 893 894 nd_set_link(nd, link); 895 return NULL; 896 } 897 898 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 899 { 900 char *s = nd_get_link(nd); 901 if (!IS_ERR(s)) 902 __putname(s); 903 } 904 905 static const struct inode_operations hostfs_link_iops = { 906 .readlink = generic_readlink, 907 .follow_link = hostfs_follow_link, 908 .put_link = hostfs_put_link, 909 }; 910 911 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 912 { 913 struct inode *root_inode; 914 char *host_root_path, *req_root = d; 915 int err; 916 917 sb->s_blocksize = 1024; 918 sb->s_blocksize_bits = 10; 919 sb->s_magic = HOSTFS_SUPER_MAGIC; 920 sb->s_op = &hostfs_sbops; 921 sb->s_d_op = &hostfs_dentry_ops; 922 sb->s_maxbytes = MAX_LFS_FILESIZE; 923 924 /* NULL is printed as <NULL> by sprintf: avoid that. */ 925 if (req_root == NULL) 926 req_root = ""; 927 928 err = -ENOMEM; 929 sb->s_fs_info = host_root_path = 930 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 931 if (host_root_path == NULL) 932 goto out; 933 934 sprintf(host_root_path, "%s/%s", root_ino, req_root); 935 936 root_inode = new_inode(sb); 937 if (!root_inode) 938 goto out; 939 940 err = read_name(root_inode, host_root_path); 941 if (err) 942 goto out_put; 943 944 if (S_ISLNK(root_inode->i_mode)) { 945 char *name = follow_link(host_root_path); 946 if (IS_ERR(name)) 947 err = PTR_ERR(name); 948 else 949 err = read_name(root_inode, name); 950 kfree(name); 951 if (err) 952 goto out_put; 953 } 954 955 err = -ENOMEM; 956 sb->s_root = d_make_root(root_inode); 957 if (sb->s_root == NULL) 958 goto out; 959 960 return 0; 961 962 out_put: 963 iput(root_inode); 964 out: 965 return err; 966 } 967 968 static struct dentry *hostfs_read_sb(struct file_system_type *type, 969 int flags, const char *dev_name, 970 void *data) 971 { 972 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 973 } 974 975 static void hostfs_kill_sb(struct super_block *s) 976 { 977 kill_anon_super(s); 978 kfree(s->s_fs_info); 979 } 980 981 static struct file_system_type hostfs_type = { 982 .owner = THIS_MODULE, 983 .name = "hostfs", 984 .mount = hostfs_read_sb, 985 .kill_sb = hostfs_kill_sb, 986 .fs_flags = 0, 987 }; 988 MODULE_ALIAS_FS("hostfs"); 989 990 static int __init init_hostfs(void) 991 { 992 return register_filesystem(&hostfs_type); 993 } 994 995 static void __exit exit_hostfs(void) 996 { 997 unregister_filesystem(&hostfs_type); 998 } 999 1000 module_init(init_hostfs) 1001 module_exit(exit_hostfs) 1002 MODULE_LICENSE("GPL"); 1003