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/module.h> 11 #include <linux/mm.h> 12 #include <linux/pagemap.h> 13 #include <linux/statfs.h> 14 #include <linux/slab.h> 15 #include <linux/seq_file.h> 16 #include <linux/mount.h> 17 #include <linux/namei.h> 18 #include "hostfs.h" 19 #include "init.h" 20 #include "kern.h" 21 22 struct hostfs_inode_info { 23 int fd; 24 fmode_t mode; 25 struct inode vfs_inode; 26 }; 27 28 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 29 { 30 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 31 } 32 33 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode) 34 35 static int hostfs_d_delete(const struct dentry *dentry) 36 { 37 return 1; 38 } 39 40 static const struct dentry_operations hostfs_dentry_ops = { 41 .d_delete = hostfs_d_delete, 42 }; 43 44 /* Changed in hostfs_args before the kernel starts running */ 45 static char *root_ino = ""; 46 static int append = 0; 47 48 #define HOSTFS_SUPER_MAGIC 0x00c0ffee 49 50 static const struct inode_operations hostfs_iops; 51 static const struct inode_operations hostfs_dir_iops; 52 static const struct inode_operations hostfs_link_iops; 53 54 #ifndef MODULE 55 static int __init hostfs_args(char *options, int *add) 56 { 57 char *ptr; 58 59 ptr = strchr(options, ','); 60 if (ptr != NULL) 61 *ptr++ = '\0'; 62 if (*options != '\0') 63 root_ino = options; 64 65 options = ptr; 66 while (options) { 67 ptr = strchr(options, ','); 68 if (ptr != NULL) 69 *ptr++ = '\0'; 70 if (*options != '\0') { 71 if (!strcmp(options, "append")) 72 append = 1; 73 else printf("hostfs_args - unsupported option - %s\n", 74 options); 75 } 76 options = ptr; 77 } 78 return 0; 79 } 80 81 __uml_setup("hostfs=", hostfs_args, 82 "hostfs=<root dir>,<flags>,...\n" 83 " This is used to set hostfs parameters. The root directory argument\n" 84 " is used to confine all hostfs mounts to within the specified directory\n" 85 " tree on the host. If this isn't specified, then a user inside UML can\n" 86 " mount anything on the host that's accessible to the user that's running\n" 87 " it.\n" 88 " The only flag currently supported is 'append', which specifies that all\n" 89 " files opened by hostfs will be opened in append mode.\n\n" 90 ); 91 #endif 92 93 static char *__dentry_name(struct dentry *dentry, char *name) 94 { 95 char *p = dentry_path_raw(dentry, name, PATH_MAX); 96 char *root; 97 size_t len; 98 99 root = dentry->d_sb->s_fs_info; 100 len = strlen(root); 101 if (IS_ERR(p)) { 102 __putname(name); 103 return NULL; 104 } 105 strlcpy(name, root, PATH_MAX); 106 if (len > p - name) { 107 __putname(name); 108 return NULL; 109 } 110 if (p > name + len) { 111 char *s = name + len; 112 while ((*s++ = *p++) != '\0') 113 ; 114 } 115 return name; 116 } 117 118 static char *dentry_name(struct dentry *dentry) 119 { 120 char *name = __getname(); 121 if (!name) 122 return NULL; 123 124 return __dentry_name(dentry, name); /* will unlock */ 125 } 126 127 static char *inode_name(struct inode *ino) 128 { 129 struct dentry *dentry; 130 char *name; 131 132 dentry = d_find_alias(ino); 133 if (!dentry) 134 return NULL; 135 136 name = dentry_name(dentry); 137 138 dput(dentry); 139 140 return name; 141 } 142 143 static char *follow_link(char *link) 144 { 145 int len, n; 146 char *name, *resolved, *end; 147 148 len = 64; 149 while (1) { 150 n = -ENOMEM; 151 name = kmalloc(len, GFP_KERNEL); 152 if (name == NULL) 153 goto out; 154 155 n = hostfs_do_readlink(link, name, len); 156 if (n < len) 157 break; 158 len *= 2; 159 kfree(name); 160 } 161 if (n < 0) 162 goto out_free; 163 164 if (*name == '/') 165 return name; 166 167 end = strrchr(link, '/'); 168 if (end == NULL) 169 return name; 170 171 *(end + 1) = '\0'; 172 len = strlen(link) + strlen(name) + 1; 173 174 resolved = kmalloc(len, GFP_KERNEL); 175 if (resolved == NULL) { 176 n = -ENOMEM; 177 goto out_free; 178 } 179 180 sprintf(resolved, "%s%s", link, name); 181 kfree(name); 182 kfree(link); 183 return resolved; 184 185 out_free: 186 kfree(name); 187 out: 188 return ERR_PTR(n); 189 } 190 191 static struct inode *hostfs_iget(struct super_block *sb) 192 { 193 struct inode *inode = new_inode(sb); 194 if (!inode) 195 return ERR_PTR(-ENOMEM); 196 return inode; 197 } 198 199 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 200 { 201 /* 202 * do_statfs uses struct statfs64 internally, but the linux kernel 203 * struct statfs still has 32-bit versions for most of these fields, 204 * so we convert them here 205 */ 206 int err; 207 long long f_blocks; 208 long long f_bfree; 209 long long f_bavail; 210 long long f_files; 211 long long f_ffree; 212 213 err = do_statfs(dentry->d_sb->s_fs_info, 214 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 215 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 216 &sf->f_namelen); 217 if (err) 218 return err; 219 sf->f_blocks = f_blocks; 220 sf->f_bfree = f_bfree; 221 sf->f_bavail = f_bavail; 222 sf->f_files = f_files; 223 sf->f_ffree = f_ffree; 224 sf->f_type = HOSTFS_SUPER_MAGIC; 225 return 0; 226 } 227 228 static struct inode *hostfs_alloc_inode(struct super_block *sb) 229 { 230 struct hostfs_inode_info *hi; 231 232 hi = kzalloc(sizeof(*hi), GFP_KERNEL); 233 if (hi == NULL) 234 return NULL; 235 hi->fd = -1; 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 end_writeback(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 ino->i_uid = st.uid; 546 ino->i_gid = 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 struct nameidata *nd) 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 struct nameidata *nd) 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 = attr->ia_uid; 812 } 813 if (attr->ia_valid & ATTR_GID) { 814 attrs.ia_valid |= HOSTFS_ATTR_GID; 815 attrs.ia_gid = 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 int error; 850 851 error = vmtruncate(inode, attr->ia_size); 852 if (err) 853 return err; 854 } 855 856 setattr_copy(inode, attr); 857 mark_inode_dirty(inode); 858 return 0; 859 } 860 861 static const struct inode_operations hostfs_iops = { 862 .create = hostfs_create, 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 const struct inode_operations hostfs_dir_iops = { 875 .create = hostfs_create, 876 .lookup = hostfs_lookup, 877 .link = hostfs_link, 878 .unlink = hostfs_unlink, 879 .symlink = hostfs_symlink, 880 .mkdir = hostfs_mkdir, 881 .rmdir = hostfs_rmdir, 882 .mknod = hostfs_mknod, 883 .rename = hostfs_rename, 884 .permission = hostfs_permission, 885 .setattr = hostfs_setattr, 886 }; 887 888 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) 889 { 890 char *link = __getname(); 891 if (link) { 892 char *path = dentry_name(dentry); 893 int err = -ENOMEM; 894 if (path) { 895 err = hostfs_do_readlink(path, link, PATH_MAX); 896 if (err == PATH_MAX) 897 err = -E2BIG; 898 __putname(path); 899 } 900 if (err < 0) { 901 __putname(link); 902 link = ERR_PTR(err); 903 } 904 } else { 905 link = ERR_PTR(-ENOMEM); 906 } 907 908 nd_set_link(nd, link); 909 return NULL; 910 } 911 912 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 913 { 914 char *s = nd_get_link(nd); 915 if (!IS_ERR(s)) 916 __putname(s); 917 } 918 919 static const struct inode_operations hostfs_link_iops = { 920 .readlink = generic_readlink, 921 .follow_link = hostfs_follow_link, 922 .put_link = hostfs_put_link, 923 }; 924 925 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 926 { 927 struct inode *root_inode; 928 char *host_root_path, *req_root = d; 929 int err; 930 931 sb->s_blocksize = 1024; 932 sb->s_blocksize_bits = 10; 933 sb->s_magic = HOSTFS_SUPER_MAGIC; 934 sb->s_op = &hostfs_sbops; 935 sb->s_d_op = &hostfs_dentry_ops; 936 sb->s_maxbytes = MAX_LFS_FILESIZE; 937 938 /* NULL is printed as <NULL> by sprintf: avoid that. */ 939 if (req_root == NULL) 940 req_root = ""; 941 942 err = -ENOMEM; 943 sb->s_fs_info = host_root_path = 944 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 945 if (host_root_path == NULL) 946 goto out; 947 948 sprintf(host_root_path, "%s/%s", root_ino, req_root); 949 950 root_inode = new_inode(sb); 951 if (!root_inode) 952 goto out; 953 954 err = read_name(root_inode, host_root_path); 955 if (err) 956 goto out_put; 957 958 if (S_ISLNK(root_inode->i_mode)) { 959 char *name = follow_link(host_root_path); 960 if (IS_ERR(name)) 961 err = PTR_ERR(name); 962 else 963 err = read_name(root_inode, name); 964 kfree(name); 965 if (err) 966 goto out_put; 967 } 968 969 err = -ENOMEM; 970 sb->s_root = d_alloc_root(root_inode); 971 if (sb->s_root == NULL) 972 goto out_put; 973 974 return 0; 975 976 out_put: 977 iput(root_inode); 978 out: 979 return err; 980 } 981 982 static struct dentry *hostfs_read_sb(struct file_system_type *type, 983 int flags, const char *dev_name, 984 void *data) 985 { 986 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 987 } 988 989 static void hostfs_kill_sb(struct super_block *s) 990 { 991 kill_anon_super(s); 992 kfree(s->s_fs_info); 993 } 994 995 static struct file_system_type hostfs_type = { 996 .owner = THIS_MODULE, 997 .name = "hostfs", 998 .mount = hostfs_read_sb, 999 .kill_sb = hostfs_kill_sb, 1000 .fs_flags = 0, 1001 }; 1002 1003 static int __init init_hostfs(void) 1004 { 1005 return register_filesystem(&hostfs_type); 1006 } 1007 1008 static void __exit exit_hostfs(void) 1009 { 1010 unregister_filesystem(&hostfs_type); 1011 } 1012 1013 module_init(init_hostfs) 1014 module_exit(exit_hostfs) 1015 MODULE_LICENSE("GPL"); 1016