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/seq_file.h> 15 #include "hostfs.h" 16 #include "init.h" 17 #include "kern.h" 18 19 struct hostfs_inode_info { 20 char *host_filename; 21 int fd; 22 int mode; 23 struct inode vfs_inode; 24 }; 25 26 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 27 { 28 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 29 } 30 31 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode) 32 33 int hostfs_d_delete(struct dentry *dentry) 34 { 35 return 1; 36 } 37 38 struct dentry_operations hostfs_dentry_ops = { 39 .d_delete = hostfs_d_delete, 40 }; 41 42 /* Changed in hostfs_args before the kernel starts running */ 43 static char *root_ino = ""; 44 static int append = 0; 45 46 #define HOSTFS_SUPER_MAGIC 0x00c0ffee 47 48 static const struct inode_operations hostfs_iops; 49 static const struct inode_operations hostfs_dir_iops; 50 static const struct address_space_operations hostfs_link_aops; 51 52 #ifndef MODULE 53 static int __init hostfs_args(char *options, int *add) 54 { 55 char *ptr; 56 57 ptr = strchr(options, ','); 58 if (ptr != NULL) 59 *ptr++ = '\0'; 60 if (*options != '\0') 61 root_ino = options; 62 63 options = ptr; 64 while (options) { 65 ptr = strchr(options, ','); 66 if (ptr != NULL) 67 *ptr++ = '\0'; 68 if (*options != '\0') { 69 if (!strcmp(options, "append")) 70 append = 1; 71 else printf("hostfs_args - unsupported option - %s\n", 72 options); 73 } 74 options = ptr; 75 } 76 return 0; 77 } 78 79 __uml_setup("hostfs=", hostfs_args, 80 "hostfs=<root dir>,<flags>,...\n" 81 " This is used to set hostfs parameters. The root directory argument\n" 82 " is used to confine all hostfs mounts to within the specified directory\n" 83 " tree on the host. If this isn't specified, then a user inside UML can\n" 84 " mount anything on the host that's accessible to the user that's running\n" 85 " it.\n" 86 " The only flag currently supported is 'append', which specifies that all\n" 87 " files opened by hostfs will be opened in append mode.\n\n" 88 ); 89 #endif 90 91 static char *dentry_name(struct dentry *dentry, int extra) 92 { 93 struct dentry *parent; 94 char *root, *name; 95 int len; 96 97 len = 0; 98 parent = dentry; 99 while (parent->d_parent != parent) { 100 len += parent->d_name.len + 1; 101 parent = parent->d_parent; 102 } 103 104 root = HOSTFS_I(parent->d_inode)->host_filename; 105 len += strlen(root); 106 name = kmalloc(len + extra + 1, GFP_KERNEL); 107 if (name == NULL) 108 return NULL; 109 110 name[len] = '\0'; 111 parent = dentry; 112 while (parent->d_parent != parent) { 113 len -= parent->d_name.len + 1; 114 name[len] = '/'; 115 strncpy(&name[len + 1], parent->d_name.name, 116 parent->d_name.len); 117 parent = parent->d_parent; 118 } 119 strncpy(name, root, strlen(root)); 120 return name; 121 } 122 123 static char *inode_name(struct inode *ino, int extra) 124 { 125 struct dentry *dentry; 126 127 dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias); 128 return dentry_name(dentry, extra); 129 } 130 131 static int read_name(struct inode *ino, char *name) 132 { 133 /* 134 * The non-int inode fields are copied into ints by stat_file and 135 * then copied into the inode because passing the actual pointers 136 * in and having them treated as int * breaks on big-endian machines 137 */ 138 int err; 139 int i_mode, i_nlink, i_blksize; 140 unsigned long long i_size; 141 unsigned long long i_ino; 142 unsigned long long i_blocks; 143 144 err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid, 145 &ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime, 146 &ino->i_ctime, &i_blksize, &i_blocks, -1); 147 if (err) 148 return err; 149 150 ino->i_ino = i_ino; 151 ino->i_mode = i_mode; 152 ino->i_nlink = i_nlink; 153 ino->i_size = i_size; 154 ino->i_blocks = i_blocks; 155 return 0; 156 } 157 158 static char *follow_link(char *link) 159 { 160 int len, n; 161 char *name, *resolved, *end; 162 163 len = 64; 164 while (1) { 165 n = -ENOMEM; 166 name = kmalloc(len, GFP_KERNEL); 167 if (name == NULL) 168 goto out; 169 170 n = do_readlink(link, name, len); 171 if (n < len) 172 break; 173 len *= 2; 174 kfree(name); 175 } 176 if (n < 0) 177 goto out_free; 178 179 if (*name == '/') 180 return name; 181 182 end = strrchr(link, '/'); 183 if (end == NULL) 184 return name; 185 186 *(end + 1) = '\0'; 187 len = strlen(link) + strlen(name) + 1; 188 189 resolved = kmalloc(len, GFP_KERNEL); 190 if (resolved == NULL) { 191 n = -ENOMEM; 192 goto out_free; 193 } 194 195 sprintf(resolved, "%s%s", link, name); 196 kfree(name); 197 kfree(link); 198 return resolved; 199 200 out_free: 201 kfree(name); 202 out: 203 return ERR_PTR(n); 204 } 205 206 static int hostfs_read_inode(struct inode *ino) 207 { 208 char *name; 209 int err = 0; 210 211 /* 212 * Unfortunately, we are called from iget() when we don't have a dentry 213 * allocated yet. 214 */ 215 if (list_empty(&ino->i_dentry)) 216 goto out; 217 218 err = -ENOMEM; 219 name = inode_name(ino, 0); 220 if (name == NULL) 221 goto out; 222 223 if (file_type(name, NULL, NULL) == OS_TYPE_SYMLINK) { 224 name = follow_link(name); 225 if (IS_ERR(name)) { 226 err = PTR_ERR(name); 227 goto out; 228 } 229 } 230 231 err = read_name(ino, name); 232 kfree(name); 233 out: 234 return err; 235 } 236 237 static struct inode *hostfs_iget(struct super_block *sb) 238 { 239 struct inode *inode; 240 long ret; 241 242 inode = iget_locked(sb, 0); 243 if (!inode) 244 return ERR_PTR(-ENOMEM); 245 if (inode->i_state & I_NEW) { 246 ret = hostfs_read_inode(inode); 247 if (ret < 0) { 248 iget_failed(inode); 249 return ERR_PTR(ret); 250 } 251 unlock_new_inode(inode); 252 } 253 return inode; 254 } 255 256 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 257 { 258 /* 259 * do_statfs uses struct statfs64 internally, but the linux kernel 260 * struct statfs still has 32-bit versions for most of these fields, 261 * so we convert them here 262 */ 263 int err; 264 long long f_blocks; 265 long long f_bfree; 266 long long f_bavail; 267 long long f_files; 268 long long f_ffree; 269 270 err = do_statfs(HOSTFS_I(dentry->d_sb->s_root->d_inode)->host_filename, 271 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 272 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 273 &sf->f_namelen, sf->f_spare); 274 if (err) 275 return err; 276 sf->f_blocks = f_blocks; 277 sf->f_bfree = f_bfree; 278 sf->f_bavail = f_bavail; 279 sf->f_files = f_files; 280 sf->f_ffree = f_ffree; 281 sf->f_type = HOSTFS_SUPER_MAGIC; 282 return 0; 283 } 284 285 static struct inode *hostfs_alloc_inode(struct super_block *sb) 286 { 287 struct hostfs_inode_info *hi; 288 289 hi = kmalloc(sizeof(*hi), GFP_KERNEL); 290 if (hi == NULL) 291 return NULL; 292 293 *hi = ((struct hostfs_inode_info) { .host_filename = NULL, 294 .fd = -1, 295 .mode = 0 }); 296 inode_init_once(&hi->vfs_inode); 297 return &hi->vfs_inode; 298 } 299 300 static void hostfs_delete_inode(struct inode *inode) 301 { 302 truncate_inode_pages(&inode->i_data, 0); 303 if (HOSTFS_I(inode)->fd != -1) { 304 close_file(&HOSTFS_I(inode)->fd); 305 HOSTFS_I(inode)->fd = -1; 306 } 307 clear_inode(inode); 308 } 309 310 static void hostfs_destroy_inode(struct inode *inode) 311 { 312 kfree(HOSTFS_I(inode)->host_filename); 313 314 /* 315 * XXX: This should not happen, probably. The check is here for 316 * additional safety. 317 */ 318 if (HOSTFS_I(inode)->fd != -1) { 319 close_file(&HOSTFS_I(inode)->fd); 320 printk(KERN_DEBUG "Closing host fd in .destroy_inode\n"); 321 } 322 323 kfree(HOSTFS_I(inode)); 324 } 325 326 static int hostfs_show_options(struct seq_file *seq, struct vfsmount *vfs) 327 { 328 struct inode *root = vfs->mnt_sb->s_root->d_inode; 329 const char *root_path = HOSTFS_I(root)->host_filename; 330 size_t offset = strlen(root_ino) + 1; 331 332 if (strlen(root_path) > offset) 333 seq_printf(seq, ",%s", root_path + offset); 334 335 return 0; 336 } 337 338 static const struct super_operations hostfs_sbops = { 339 .alloc_inode = hostfs_alloc_inode, 340 .drop_inode = generic_delete_inode, 341 .delete_inode = hostfs_delete_inode, 342 .destroy_inode = hostfs_destroy_inode, 343 .statfs = hostfs_statfs, 344 .show_options = hostfs_show_options, 345 }; 346 347 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir) 348 { 349 void *dir; 350 char *name; 351 unsigned long long next, ino; 352 int error, len; 353 354 name = dentry_name(file->f_path.dentry, 0); 355 if (name == NULL) 356 return -ENOMEM; 357 dir = open_dir(name, &error); 358 kfree(name); 359 if (dir == NULL) 360 return -error; 361 next = file->f_pos; 362 while ((name = read_dir(dir, &next, &ino, &len)) != NULL) { 363 error = (*filldir)(ent, name, len, file->f_pos, 364 ino, DT_UNKNOWN); 365 if (error) break; 366 file->f_pos = next; 367 } 368 close_dir(dir); 369 return 0; 370 } 371 372 int hostfs_file_open(struct inode *ino, struct file *file) 373 { 374 char *name; 375 int mode = 0, r = 0, w = 0, fd; 376 377 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 378 if ((mode & HOSTFS_I(ino)->mode) == mode) 379 return 0; 380 381 /* 382 * The file may already have been opened, but with the wrong access, 383 * so this resets things and reopens the file with the new access. 384 */ 385 if (HOSTFS_I(ino)->fd != -1) { 386 close_file(&HOSTFS_I(ino)->fd); 387 HOSTFS_I(ino)->fd = -1; 388 } 389 390 HOSTFS_I(ino)->mode |= mode; 391 if (HOSTFS_I(ino)->mode & FMODE_READ) 392 r = 1; 393 if (HOSTFS_I(ino)->mode & FMODE_WRITE) 394 w = 1; 395 if (w) 396 r = 1; 397 398 name = dentry_name(file->f_path.dentry, 0); 399 if (name == NULL) 400 return -ENOMEM; 401 402 fd = open_file(name, r, w, append); 403 kfree(name); 404 if (fd < 0) 405 return fd; 406 FILE_HOSTFS_I(file)->fd = fd; 407 408 return 0; 409 } 410 411 int hostfs_fsync(struct file *file, struct dentry *dentry, int datasync) 412 { 413 return fsync_file(HOSTFS_I(dentry->d_inode)->fd, datasync); 414 } 415 416 static const struct file_operations hostfs_file_fops = { 417 .llseek = generic_file_llseek, 418 .read = do_sync_read, 419 .splice_read = generic_file_splice_read, 420 .aio_read = generic_file_aio_read, 421 .aio_write = generic_file_aio_write, 422 .write = do_sync_write, 423 .mmap = generic_file_mmap, 424 .open = hostfs_file_open, 425 .release = NULL, 426 .fsync = hostfs_fsync, 427 }; 428 429 static const struct file_operations hostfs_dir_fops = { 430 .llseek = generic_file_llseek, 431 .readdir = hostfs_readdir, 432 .read = generic_read_dir, 433 }; 434 435 int hostfs_writepage(struct page *page, struct writeback_control *wbc) 436 { 437 struct address_space *mapping = page->mapping; 438 struct inode *inode = mapping->host; 439 char *buffer; 440 unsigned long long base; 441 int count = PAGE_CACHE_SIZE; 442 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 443 int err; 444 445 if (page->index >= end_index) 446 count = inode->i_size & (PAGE_CACHE_SIZE-1); 447 448 buffer = kmap(page); 449 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; 450 451 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 452 if (err != count) { 453 ClearPageUptodate(page); 454 goto out; 455 } 456 457 if (base > inode->i_size) 458 inode->i_size = base; 459 460 if (PageError(page)) 461 ClearPageError(page); 462 err = 0; 463 464 out: 465 kunmap(page); 466 467 unlock_page(page); 468 return err; 469 } 470 471 int hostfs_readpage(struct file *file, struct page *page) 472 { 473 char *buffer; 474 long long start; 475 int err = 0; 476 477 start = (long long) page->index << PAGE_CACHE_SHIFT; 478 buffer = kmap(page); 479 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 480 PAGE_CACHE_SIZE); 481 if (err < 0) 482 goto out; 483 484 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); 485 486 flush_dcache_page(page); 487 SetPageUptodate(page); 488 if (PageError(page)) ClearPageError(page); 489 err = 0; 490 out: 491 kunmap(page); 492 unlock_page(page); 493 return err; 494 } 495 496 int hostfs_write_begin(struct file *file, struct address_space *mapping, 497 loff_t pos, unsigned len, unsigned flags, 498 struct page **pagep, void **fsdata) 499 { 500 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 501 502 *pagep = __grab_cache_page(mapping, index); 503 if (!*pagep) 504 return -ENOMEM; 505 return 0; 506 } 507 508 int hostfs_write_end(struct file *file, struct address_space *mapping, 509 loff_t pos, unsigned len, unsigned copied, 510 struct page *page, void *fsdata) 511 { 512 struct inode *inode = mapping->host; 513 void *buffer; 514 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 515 int err; 516 517 buffer = kmap(page); 518 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 519 kunmap(page); 520 521 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE) 522 SetPageUptodate(page); 523 524 /* 525 * If err > 0, write_file has added err to pos, so we are comparing 526 * i_size against the last byte written. 527 */ 528 if (err > 0 && (pos > inode->i_size)) 529 inode->i_size = pos; 530 unlock_page(page); 531 page_cache_release(page); 532 533 return err; 534 } 535 536 static const struct address_space_operations hostfs_aops = { 537 .writepage = hostfs_writepage, 538 .readpage = hostfs_readpage, 539 .set_page_dirty = __set_page_dirty_nobuffers, 540 .write_begin = hostfs_write_begin, 541 .write_end = hostfs_write_end, 542 }; 543 544 static int init_inode(struct inode *inode, struct dentry *dentry) 545 { 546 char *name; 547 int type, err = -ENOMEM; 548 int maj, min; 549 dev_t rdev = 0; 550 551 if (dentry) { 552 name = dentry_name(dentry, 0); 553 if (name == NULL) 554 goto out; 555 type = file_type(name, &maj, &min); 556 /* Reencode maj and min with the kernel encoding.*/ 557 rdev = MKDEV(maj, min); 558 kfree(name); 559 } 560 else type = OS_TYPE_DIR; 561 562 err = 0; 563 if (type == OS_TYPE_SYMLINK) 564 inode->i_op = &page_symlink_inode_operations; 565 else if (type == OS_TYPE_DIR) 566 inode->i_op = &hostfs_dir_iops; 567 else inode->i_op = &hostfs_iops; 568 569 if (type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops; 570 else inode->i_fop = &hostfs_file_fops; 571 572 if (type == OS_TYPE_SYMLINK) 573 inode->i_mapping->a_ops = &hostfs_link_aops; 574 else inode->i_mapping->a_ops = &hostfs_aops; 575 576 switch (type) { 577 case OS_TYPE_CHARDEV: 578 init_special_inode(inode, S_IFCHR, rdev); 579 break; 580 case OS_TYPE_BLOCKDEV: 581 init_special_inode(inode, S_IFBLK, rdev); 582 break; 583 case OS_TYPE_FIFO: 584 init_special_inode(inode, S_IFIFO, 0); 585 break; 586 case OS_TYPE_SOCK: 587 init_special_inode(inode, S_IFSOCK, 0); 588 break; 589 } 590 out: 591 return err; 592 } 593 594 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode, 595 struct nameidata *nd) 596 { 597 struct inode *inode; 598 char *name; 599 int error, fd; 600 601 inode = hostfs_iget(dir->i_sb); 602 if (IS_ERR(inode)) { 603 error = PTR_ERR(inode); 604 goto out; 605 } 606 607 error = init_inode(inode, dentry); 608 if (error) 609 goto out_put; 610 611 error = -ENOMEM; 612 name = dentry_name(dentry, 0); 613 if (name == NULL) 614 goto out_put; 615 616 fd = file_create(name, 617 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, 618 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, 619 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); 620 if (fd < 0) 621 error = fd; 622 else error = read_name(inode, name); 623 624 kfree(name); 625 if (error) 626 goto out_put; 627 628 HOSTFS_I(inode)->fd = fd; 629 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 630 d_instantiate(dentry, inode); 631 return 0; 632 633 out_put: 634 iput(inode); 635 out: 636 return error; 637 } 638 639 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 640 struct nameidata *nd) 641 { 642 struct inode *inode; 643 char *name; 644 int err; 645 646 inode = hostfs_iget(ino->i_sb); 647 if (IS_ERR(inode)) { 648 err = PTR_ERR(inode); 649 goto out; 650 } 651 652 err = init_inode(inode, dentry); 653 if (err) 654 goto out_put; 655 656 err = -ENOMEM; 657 name = dentry_name(dentry, 0); 658 if (name == NULL) 659 goto out_put; 660 661 err = read_name(inode, name); 662 kfree(name); 663 if (err == -ENOENT) { 664 iput(inode); 665 inode = NULL; 666 } 667 else if (err) 668 goto out_put; 669 670 d_add(dentry, inode); 671 dentry->d_op = &hostfs_dentry_ops; 672 return NULL; 673 674 out_put: 675 iput(inode); 676 out: 677 return ERR_PTR(err); 678 } 679 680 static char *inode_dentry_name(struct inode *ino, struct dentry *dentry) 681 { 682 char *file; 683 int len; 684 685 file = inode_name(ino, dentry->d_name.len + 1); 686 if (file == NULL) 687 return NULL; 688 strcat(file, "/"); 689 len = strlen(file); 690 strncat(file, dentry->d_name.name, dentry->d_name.len); 691 file[len + dentry->d_name.len] = '\0'; 692 return file; 693 } 694 695 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from) 696 { 697 char *from_name, *to_name; 698 int err; 699 700 if ((from_name = inode_dentry_name(ino, from)) == NULL) 701 return -ENOMEM; 702 to_name = dentry_name(to, 0); 703 if (to_name == NULL) { 704 kfree(from_name); 705 return -ENOMEM; 706 } 707 err = link_file(to_name, from_name); 708 kfree(from_name); 709 kfree(to_name); 710 return err; 711 } 712 713 int hostfs_unlink(struct inode *ino, struct dentry *dentry) 714 { 715 char *file; 716 int err; 717 718 if ((file = inode_dentry_name(ino, dentry)) == NULL) 719 return -ENOMEM; 720 if (append) 721 return -EPERM; 722 723 err = unlink_file(file); 724 kfree(file); 725 return err; 726 } 727 728 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to) 729 { 730 char *file; 731 int err; 732 733 if ((file = inode_dentry_name(ino, dentry)) == NULL) 734 return -ENOMEM; 735 err = make_symlink(file, to); 736 kfree(file); 737 return err; 738 } 739 740 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode) 741 { 742 char *file; 743 int err; 744 745 if ((file = inode_dentry_name(ino, dentry)) == NULL) 746 return -ENOMEM; 747 err = do_mkdir(file, mode); 748 kfree(file); 749 return err; 750 } 751 752 int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 753 { 754 char *file; 755 int err; 756 757 if ((file = inode_dentry_name(ino, dentry)) == NULL) 758 return -ENOMEM; 759 err = do_rmdir(file); 760 kfree(file); 761 return err; 762 } 763 764 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 765 { 766 struct inode *inode; 767 char *name; 768 int err; 769 770 inode = hostfs_iget(dir->i_sb); 771 if (IS_ERR(inode)) { 772 err = PTR_ERR(inode); 773 goto out; 774 } 775 776 err = init_inode(inode, dentry); 777 if (err) 778 goto out_put; 779 780 err = -ENOMEM; 781 name = dentry_name(dentry, 0); 782 if (name == NULL) 783 goto out_put; 784 785 init_special_inode(inode, mode, dev); 786 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 787 if (err) 788 goto out_free; 789 790 err = read_name(inode, name); 791 kfree(name); 792 if (err) 793 goto out_put; 794 795 d_instantiate(dentry, inode); 796 return 0; 797 798 out_free: 799 kfree(name); 800 out_put: 801 iput(inode); 802 out: 803 return err; 804 } 805 806 int hostfs_rename(struct inode *from_ino, struct dentry *from, 807 struct inode *to_ino, struct dentry *to) 808 { 809 char *from_name, *to_name; 810 int err; 811 812 if ((from_name = inode_dentry_name(from_ino, from)) == NULL) 813 return -ENOMEM; 814 if ((to_name = inode_dentry_name(to_ino, to)) == NULL) { 815 kfree(from_name); 816 return -ENOMEM; 817 } 818 err = rename_file(from_name, to_name); 819 kfree(from_name); 820 kfree(to_name); 821 return err; 822 } 823 824 int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd) 825 { 826 char *name; 827 int r = 0, w = 0, x = 0, err; 828 829 if (desired & MAY_READ) r = 1; 830 if (desired & MAY_WRITE) w = 1; 831 if (desired & MAY_EXEC) x = 1; 832 name = inode_name(ino, 0); 833 if (name == NULL) 834 return -ENOMEM; 835 836 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 837 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 838 err = 0; 839 else 840 err = access_file(name, r, w, x); 841 kfree(name); 842 if (!err) 843 err = generic_permission(ino, desired, NULL); 844 return err; 845 } 846 847 int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 848 { 849 struct hostfs_iattr attrs; 850 char *name; 851 int err; 852 853 int fd = HOSTFS_I(dentry->d_inode)->fd; 854 855 err = inode_change_ok(dentry->d_inode, attr); 856 if (err) 857 return err; 858 859 if (append) 860 attr->ia_valid &= ~ATTR_SIZE; 861 862 attrs.ia_valid = 0; 863 if (attr->ia_valid & ATTR_MODE) { 864 attrs.ia_valid |= HOSTFS_ATTR_MODE; 865 attrs.ia_mode = attr->ia_mode; 866 } 867 if (attr->ia_valid & ATTR_UID) { 868 attrs.ia_valid |= HOSTFS_ATTR_UID; 869 attrs.ia_uid = attr->ia_uid; 870 } 871 if (attr->ia_valid & ATTR_GID) { 872 attrs.ia_valid |= HOSTFS_ATTR_GID; 873 attrs.ia_gid = attr->ia_gid; 874 } 875 if (attr->ia_valid & ATTR_SIZE) { 876 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 877 attrs.ia_size = attr->ia_size; 878 } 879 if (attr->ia_valid & ATTR_ATIME) { 880 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 881 attrs.ia_atime = attr->ia_atime; 882 } 883 if (attr->ia_valid & ATTR_MTIME) { 884 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 885 attrs.ia_mtime = attr->ia_mtime; 886 } 887 if (attr->ia_valid & ATTR_CTIME) { 888 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 889 attrs.ia_ctime = attr->ia_ctime; 890 } 891 if (attr->ia_valid & ATTR_ATIME_SET) { 892 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 893 } 894 if (attr->ia_valid & ATTR_MTIME_SET) { 895 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 896 } 897 name = dentry_name(dentry, 0); 898 if (name == NULL) 899 return -ENOMEM; 900 err = set_attr(name, &attrs, fd); 901 kfree(name); 902 if (err) 903 return err; 904 905 return inode_setattr(dentry->d_inode, attr); 906 } 907 908 static const struct inode_operations hostfs_iops = { 909 .create = hostfs_create, 910 .link = hostfs_link, 911 .unlink = hostfs_unlink, 912 .symlink = hostfs_symlink, 913 .mkdir = hostfs_mkdir, 914 .rmdir = hostfs_rmdir, 915 .mknod = hostfs_mknod, 916 .rename = hostfs_rename, 917 .permission = hostfs_permission, 918 .setattr = hostfs_setattr, 919 }; 920 921 static const struct inode_operations hostfs_dir_iops = { 922 .create = hostfs_create, 923 .lookup = hostfs_lookup, 924 .link = hostfs_link, 925 .unlink = hostfs_unlink, 926 .symlink = hostfs_symlink, 927 .mkdir = hostfs_mkdir, 928 .rmdir = hostfs_rmdir, 929 .mknod = hostfs_mknod, 930 .rename = hostfs_rename, 931 .permission = hostfs_permission, 932 .setattr = hostfs_setattr, 933 }; 934 935 int hostfs_link_readpage(struct file *file, struct page *page) 936 { 937 char *buffer, *name; 938 int err; 939 940 buffer = kmap(page); 941 name = inode_name(page->mapping->host, 0); 942 if (name == NULL) 943 return -ENOMEM; 944 err = do_readlink(name, buffer, PAGE_CACHE_SIZE); 945 kfree(name); 946 if (err == PAGE_CACHE_SIZE) 947 err = -E2BIG; 948 else if (err > 0) { 949 flush_dcache_page(page); 950 SetPageUptodate(page); 951 if (PageError(page)) ClearPageError(page); 952 err = 0; 953 } 954 kunmap(page); 955 unlock_page(page); 956 return err; 957 } 958 959 static const struct address_space_operations hostfs_link_aops = { 960 .readpage = hostfs_link_readpage, 961 }; 962 963 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 964 { 965 struct inode *root_inode; 966 char *host_root_path, *req_root = d; 967 int err; 968 969 sb->s_blocksize = 1024; 970 sb->s_blocksize_bits = 10; 971 sb->s_magic = HOSTFS_SUPER_MAGIC; 972 sb->s_op = &hostfs_sbops; 973 974 /* NULL is printed as <NULL> by sprintf: avoid that. */ 975 if (req_root == NULL) 976 req_root = ""; 977 978 err = -ENOMEM; 979 host_root_path = kmalloc(strlen(root_ino) + 1 980 + strlen(req_root) + 1, GFP_KERNEL); 981 if (host_root_path == NULL) 982 goto out; 983 984 sprintf(host_root_path, "%s/%s", root_ino, req_root); 985 986 root_inode = hostfs_iget(sb); 987 if (IS_ERR(root_inode)) { 988 err = PTR_ERR(root_inode); 989 goto out_free; 990 } 991 992 err = init_inode(root_inode, NULL); 993 if (err) 994 goto out_put; 995 996 HOSTFS_I(root_inode)->host_filename = host_root_path; 997 /* 998 * Avoid that in the error path, iput(root_inode) frees again 999 * host_root_path through hostfs_destroy_inode! 1000 */ 1001 host_root_path = NULL; 1002 1003 err = -ENOMEM; 1004 sb->s_root = d_alloc_root(root_inode); 1005 if (sb->s_root == NULL) 1006 goto out_put; 1007 1008 err = hostfs_read_inode(root_inode); 1009 if (err) { 1010 /* No iput in this case because the dput does that for us */ 1011 dput(sb->s_root); 1012 sb->s_root = NULL; 1013 goto out; 1014 } 1015 1016 return 0; 1017 1018 out_put: 1019 iput(root_inode); 1020 out_free: 1021 kfree(host_root_path); 1022 out: 1023 return err; 1024 } 1025 1026 static int hostfs_read_sb(struct file_system_type *type, 1027 int flags, const char *dev_name, 1028 void *data, struct vfsmount *mnt) 1029 { 1030 return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt); 1031 } 1032 1033 static struct file_system_type hostfs_type = { 1034 .owner = THIS_MODULE, 1035 .name = "hostfs", 1036 .get_sb = hostfs_read_sb, 1037 .kill_sb = kill_anon_super, 1038 .fs_flags = 0, 1039 }; 1040 1041 static int __init init_hostfs(void) 1042 { 1043 return register_filesystem(&hostfs_type); 1044 } 1045 1046 static void __exit exit_hostfs(void) 1047 { 1048 unregister_filesystem(&hostfs_type); 1049 } 1050 1051 module_init(init_hostfs) 1052 module_exit(exit_hostfs) 1053 MODULE_LICENSE("GPL"); 1054