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 struct mutex open_mutex;
28 };
29
30 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
31 {
32 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
33 }
34
35 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file))
36
37 /* Changed in hostfs_args before the kernel starts running */
38 static char *root_ino = "";
39 static int append = 0;
40
41 static const struct inode_operations hostfs_iops;
42 static const struct inode_operations hostfs_dir_iops;
43 static const struct inode_operations hostfs_link_iops;
44
45 #ifndef MODULE
46 static int __init hostfs_args(char *options, int *add)
47 {
48 char *ptr;
49
50 ptr = strchr(options, ',');
51 if (ptr != NULL)
52 *ptr++ = '\0';
53 if (*options != '\0')
54 root_ino = options;
55
56 options = ptr;
57 while (options) {
58 ptr = strchr(options, ',');
59 if (ptr != NULL)
60 *ptr++ = '\0';
61 if (*options != '\0') {
62 if (!strcmp(options, "append"))
63 append = 1;
64 else printf("hostfs_args - unsupported option - %s\n",
65 options);
66 }
67 options = ptr;
68 }
69 return 0;
70 }
71
72 __uml_setup("hostfs=", hostfs_args,
73 "hostfs=<root dir>,<flags>,...\n"
74 " This is used to set hostfs parameters. The root directory argument\n"
75 " is used to confine all hostfs mounts to within the specified directory\n"
76 " tree on the host. If this isn't specified, then a user inside UML can\n"
77 " mount anything on the host that's accessible to the user that's running\n"
78 " it.\n"
79 " The only flag currently supported is 'append', which specifies that all\n"
80 " files opened by hostfs will be opened in append mode.\n\n"
81 );
82 #endif
83
84 static char *__dentry_name(struct dentry *dentry, char *name)
85 {
86 char *p = dentry_path_raw(dentry, name, PATH_MAX);
87 char *root;
88 size_t len;
89
90 root = dentry->d_sb->s_fs_info;
91 len = strlen(root);
92 if (IS_ERR(p)) {
93 __putname(name);
94 return NULL;
95 }
96
97 /*
98 * This function relies on the fact that dentry_path_raw() will place
99 * the path name at the end of the provided buffer.
100 */
101 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX);
102
103 strlcpy(name, root, PATH_MAX);
104 if (len > p - name) {
105 __putname(name);
106 return NULL;
107 }
108
109 if (p > name + len)
110 strcpy(name + len, p);
111
112 return name;
113 }
114
115 static char *dentry_name(struct dentry *dentry)
116 {
117 char *name = __getname();
118 if (!name)
119 return NULL;
120
121 return __dentry_name(dentry, name);
122 }
123
124 static char *inode_name(struct inode *ino)
125 {
126 struct dentry *dentry;
127 char *name;
128
129 dentry = d_find_alias(ino);
130 if (!dentry)
131 return NULL;
132
133 name = dentry_name(dentry);
134
135 dput(dentry);
136
137 return name;
138 }
139
140 static char *follow_link(char *link)
141 {
142 char *name, *resolved, *end;
143 int n;
144
145 name = kmalloc(PATH_MAX, GFP_KERNEL);
146 if (!name) {
147 n = -ENOMEM;
148 goto out_free;
149 }
150
151 n = hostfs_do_readlink(link, name, PATH_MAX);
152 if (n < 0)
153 goto out_free;
154 else if (n == PATH_MAX) {
155 n = -E2BIG;
156 goto out_free;
157 }
158
159 if (*name == '/')
160 return name;
161
162 end = strrchr(link, '/');
163 if (end == NULL)
164 return name;
165
166 *(end + 1) = '\0';
167
168 resolved = kasprintf(GFP_KERNEL, "%s%s", link, name);
169 if (resolved == NULL) {
170 n = -ENOMEM;
171 goto out_free;
172 }
173
174 kfree(name);
175 return resolved;
176
177 out_free:
178 kfree(name);
179 return ERR_PTR(n);
180 }
181
182 static struct inode *hostfs_iget(struct super_block *sb)
183 {
184 struct inode *inode = new_inode(sb);
185 if (!inode)
186 return ERR_PTR(-ENOMEM);
187 return inode;
188 }
189
190 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
191 {
192 /*
193 * do_statfs uses struct statfs64 internally, but the linux kernel
194 * struct statfs still has 32-bit versions for most of these fields,
195 * so we convert them here
196 */
197 int err;
198 long long f_blocks;
199 long long f_bfree;
200 long long f_bavail;
201 long long f_files;
202 long long f_ffree;
203
204 err = do_statfs(dentry->d_sb->s_fs_info,
205 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
206 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
207 &sf->f_namelen);
208 if (err)
209 return err;
210 sf->f_blocks = f_blocks;
211 sf->f_bfree = f_bfree;
212 sf->f_bavail = f_bavail;
213 sf->f_files = f_files;
214 sf->f_ffree = f_ffree;
215 sf->f_type = HOSTFS_SUPER_MAGIC;
216 return 0;
217 }
218
219 static struct inode *hostfs_alloc_inode(struct super_block *sb)
220 {
221 struct hostfs_inode_info *hi;
222
223 hi = kmalloc(sizeof(*hi), GFP_KERNEL_ACCOUNT);
224 if (hi == NULL)
225 return NULL;
226 hi->fd = -1;
227 hi->mode = 0;
228 inode_init_once(&hi->vfs_inode);
229 mutex_init(&hi->open_mutex);
230 return &hi->vfs_inode;
231 }
232
233 static void hostfs_evict_inode(struct inode *inode)
234 {
235 truncate_inode_pages_final(&inode->i_data);
236 clear_inode(inode);
237 if (HOSTFS_I(inode)->fd != -1) {
238 close_file(&HOSTFS_I(inode)->fd);
239 HOSTFS_I(inode)->fd = -1;
240 }
241 }
242
243 static void hostfs_free_inode(struct inode *inode)
244 {
245 kfree(HOSTFS_I(inode));
246 }
247
248 static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
249 {
250 const char *root_path = root->d_sb->s_fs_info;
251 size_t offset = strlen(root_ino) + 1;
252
253 if (strlen(root_path) > offset)
254 seq_show_option(seq, root_path + offset, NULL);
255
256 if (append)
257 seq_puts(seq, ",append");
258
259 return 0;
260 }
261
262 static const struct super_operations hostfs_sbops = {
263 .alloc_inode = hostfs_alloc_inode,
264 .free_inode = hostfs_free_inode,
265 .evict_inode = hostfs_evict_inode,
266 .statfs = hostfs_statfs,
267 .show_options = hostfs_show_options,
268 };
269
270 static int hostfs_readdir(struct file *file, struct dir_context *ctx)
271 {
272 void *dir;
273 char *name;
274 unsigned long long next, ino;
275 int error, len;
276 unsigned int type;
277
278 name = dentry_name(file->f_path.dentry);
279 if (name == NULL)
280 return -ENOMEM;
281 dir = open_dir(name, &error);
282 __putname(name);
283 if (dir == NULL)
284 return -error;
285 next = ctx->pos;
286 seek_dir(dir, next);
287 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
288 if (!dir_emit(ctx, name, len, ino, type))
289 break;
290 ctx->pos = next;
291 }
292 close_dir(dir);
293 return 0;
294 }
295
296 static int hostfs_open(struct inode *ino, struct file *file)
297 {
298 char *name;
299 fmode_t mode;
300 int err;
301 int r, w, fd;
302
303 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
304 if ((mode & HOSTFS_I(ino)->mode) == mode)
305 return 0;
306
307 mode |= HOSTFS_I(ino)->mode;
308
309 retry:
310 r = w = 0;
311
312 if (mode & FMODE_READ)
313 r = 1;
314 if (mode & FMODE_WRITE)
315 r = w = 1;
316
317 name = dentry_name(d_real(file->f_path.dentry, file->f_inode));
318 if (name == NULL)
319 return -ENOMEM;
320
321 fd = open_file(name, r, w, append);
322 __putname(name);
323 if (fd < 0)
324 return fd;
325
326 mutex_lock(&HOSTFS_I(ino)->open_mutex);
327 /* somebody else had handled it first? */
328 if ((mode & HOSTFS_I(ino)->mode) == mode) {
329 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
330 close_file(&fd);
331 return 0;
332 }
333 if ((mode | HOSTFS_I(ino)->mode) != mode) {
334 mode |= HOSTFS_I(ino)->mode;
335 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
336 close_file(&fd);
337 goto retry;
338 }
339 if (HOSTFS_I(ino)->fd == -1) {
340 HOSTFS_I(ino)->fd = fd;
341 } else {
342 err = replace_file(fd, HOSTFS_I(ino)->fd);
343 close_file(&fd);
344 if (err < 0) {
345 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
346 return err;
347 }
348 }
349 HOSTFS_I(ino)->mode = mode;
350 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
351
352 return 0;
353 }
354
355 static int hostfs_file_release(struct inode *inode, struct file *file)
356 {
357 filemap_write_and_wait(inode->i_mapping);
358
359 return 0;
360 }
361
362 static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
363 int datasync)
364 {
365 struct inode *inode = file->f_mapping->host;
366 int ret;
367
368 ret = file_write_and_wait_range(file, start, end);
369 if (ret)
370 return ret;
371
372 inode_lock(inode);
373 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
374 inode_unlock(inode);
375
376 return ret;
377 }
378
379 static const struct file_operations hostfs_file_fops = {
380 .llseek = generic_file_llseek,
381 .splice_read = generic_file_splice_read,
382 .read_iter = generic_file_read_iter,
383 .write_iter = generic_file_write_iter,
384 .mmap = generic_file_mmap,
385 .open = hostfs_open,
386 .release = hostfs_file_release,
387 .fsync = hostfs_fsync,
388 };
389
390 static const struct file_operations hostfs_dir_fops = {
391 .llseek = generic_file_llseek,
392 .iterate_shared = hostfs_readdir,
393 .read = generic_read_dir,
394 .open = hostfs_open,
395 .fsync = hostfs_fsync,
396 };
397
398 static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
399 {
400 struct address_space *mapping = page->mapping;
401 struct inode *inode = mapping->host;
402 char *buffer;
403 loff_t base = page_offset(page);
404 int count = PAGE_SIZE;
405 int end_index = inode->i_size >> PAGE_SHIFT;
406 int err;
407
408 if (page->index >= end_index)
409 count = inode->i_size & (PAGE_SIZE-1);
410
411 buffer = kmap(page);
412
413 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
414 if (err != count) {
415 ClearPageUptodate(page);
416 goto out;
417 }
418
419 if (base > inode->i_size)
420 inode->i_size = base;
421
422 if (PageError(page))
423 ClearPageError(page);
424 err = 0;
425
426 out:
427 kunmap(page);
428
429 unlock_page(page);
430 return err;
431 }
432
433 static int hostfs_readpage(struct file *file, struct page *page)
434 {
435 char *buffer;
436 loff_t start = page_offset(page);
437 int bytes_read, ret = 0;
438
439 buffer = kmap(page);
440 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
441 PAGE_SIZE);
442 if (bytes_read < 0) {
443 ClearPageUptodate(page);
444 SetPageError(page);
445 ret = bytes_read;
446 goto out;
447 }
448
449 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read);
450
451 ClearPageError(page);
452 SetPageUptodate(page);
453
454 out:
455 flush_dcache_page(page);
456 kunmap(page);
457 unlock_page(page);
458 return ret;
459 }
460
461 static 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_SHIFT;
466
467 *pagep = grab_cache_page_write_begin(mapping, index, flags);
468 if (!*pagep)
469 return -ENOMEM;
470 return 0;
471 }
472
473 static 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_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_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 put_page(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 case S_IFREG:
536 ino->i_op = &hostfs_iops;
537 ino->i_fop = &hostfs_file_fops;
538 ino->i_mapping->a_ops = &hostfs_aops;
539 break;
540 default:
541 return -EIO;
542 }
543
544 ino->i_ino = st.ino;
545 ino->i_mode = st.mode;
546 set_nlink(ino, st.nlink);
547 i_uid_write(ino, st.uid);
548 i_gid_write(ino, st.gid);
549 ino->i_atime = (struct timespec64){ st.atime.tv_sec, st.atime.tv_nsec };
550 ino->i_mtime = (struct timespec64){ st.mtime.tv_sec, st.mtime.tv_nsec };
551 ino->i_ctime = (struct timespec64){ st.ctime.tv_sec, st.ctime.tv_nsec };
552 ino->i_size = st.size;
553 ino->i_blocks = st.blocks;
554 return 0;
555 }
556
557 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
558 bool excl)
559 {
560 struct inode *inode;
561 char *name;
562 int error, fd;
563
564 inode = hostfs_iget(dir->i_sb);
565 if (IS_ERR(inode)) {
566 error = PTR_ERR(inode);
567 goto out;
568 }
569
570 error = -ENOMEM;
571 name = dentry_name(dentry);
572 if (name == NULL)
573 goto out_put;
574
575 fd = file_create(name, mode & 0777);
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 static 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 goto out;
606
607 err = -ENOMEM;
608 name = dentry_name(dentry);
609 if (name) {
610 err = read_name(inode, name);
611 __putname(name);
612 }
613 if (err) {
614 iput(inode);
615 inode = (err == -ENOENT) ? NULL : ERR_PTR(err);
616 }
617 out:
618 return d_splice_alias(inode, dentry);
619 }
620
621 static int hostfs_link(struct dentry *to, struct inode *ino,
622 struct dentry *from)
623 {
624 char *from_name, *to_name;
625 int err;
626
627 if ((from_name = dentry_name(from)) == NULL)
628 return -ENOMEM;
629 to_name = dentry_name(to);
630 if (to_name == NULL) {
631 __putname(from_name);
632 return -ENOMEM;
633 }
634 err = link_file(to_name, from_name);
635 __putname(from_name);
636 __putname(to_name);
637 return err;
638 }
639
640 static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
641 {
642 char *file;
643 int err;
644
645 if (append)
646 return -EPERM;
647
648 if ((file = dentry_name(dentry)) == NULL)
649 return -ENOMEM;
650
651 err = unlink_file(file);
652 __putname(file);
653 return err;
654 }
655
656 static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
657 const char *to)
658 {
659 char *file;
660 int err;
661
662 if ((file = dentry_name(dentry)) == NULL)
663 return -ENOMEM;
664 err = make_symlink(file, to);
665 __putname(file);
666 return err;
667 }
668
669 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
670 {
671 char *file;
672 int err;
673
674 if ((file = dentry_name(dentry)) == NULL)
675 return -ENOMEM;
676 err = do_mkdir(file, mode);
677 __putname(file);
678 return err;
679 }
680
681 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
682 {
683 char *file;
684 int err;
685
686 if ((file = dentry_name(dentry)) == NULL)
687 return -ENOMEM;
688 err = hostfs_do_rmdir(file);
689 __putname(file);
690 return err;
691 }
692
693 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
694 {
695 struct inode *inode;
696 char *name;
697 int err;
698
699 inode = hostfs_iget(dir->i_sb);
700 if (IS_ERR(inode)) {
701 err = PTR_ERR(inode);
702 goto out;
703 }
704
705 err = -ENOMEM;
706 name = dentry_name(dentry);
707 if (name == NULL)
708 goto out_put;
709
710 init_special_inode(inode, mode, dev);
711 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
712 if (err)
713 goto out_free;
714
715 err = read_name(inode, name);
716 __putname(name);
717 if (err)
718 goto out_put;
719
720 d_instantiate(dentry, inode);
721 return 0;
722
723 out_free:
724 __putname(name);
725 out_put:
726 iput(inode);
727 out:
728 return err;
729 }
730
731 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
732 struct inode *new_dir, struct dentry *new_dentry,
733 unsigned int flags)
734 {
735 char *old_name, *new_name;
736 int err;
737
738 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
739 return -EINVAL;
740
741 old_name = dentry_name(old_dentry);
742 if (old_name == NULL)
743 return -ENOMEM;
744 new_name = dentry_name(new_dentry);
745 if (new_name == NULL) {
746 __putname(old_name);
747 return -ENOMEM;
748 }
749 if (!flags)
750 err = rename_file(old_name, new_name);
751 else
752 err = rename2_file(old_name, new_name, flags);
753
754 __putname(old_name);
755 __putname(new_name);
756 return err;
757 }
758
759 static int hostfs_permission(struct inode *ino, int desired)
760 {
761 char *name;
762 int r = 0, w = 0, x = 0, err;
763
764 if (desired & MAY_NOT_BLOCK)
765 return -ECHILD;
766
767 if (desired & MAY_READ) r = 1;
768 if (desired & MAY_WRITE) w = 1;
769 if (desired & MAY_EXEC) x = 1;
770 name = inode_name(ino);
771 if (name == NULL)
772 return -ENOMEM;
773
774 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
775 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
776 err = 0;
777 else
778 err = access_file(name, r, w, x);
779 __putname(name);
780 if (!err)
781 err = generic_permission(ino, desired);
782 return err;
783 }
784
785 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
786 {
787 struct inode *inode = d_inode(dentry);
788 struct hostfs_iattr attrs;
789 char *name;
790 int err;
791
792 int fd = HOSTFS_I(inode)->fd;
793
794 err = setattr_prepare(dentry, attr);
795 if (err)
796 return err;
797
798 if (append)
799 attr->ia_valid &= ~ATTR_SIZE;
800
801 attrs.ia_valid = 0;
802 if (attr->ia_valid & ATTR_MODE) {
803 attrs.ia_valid |= HOSTFS_ATTR_MODE;
804 attrs.ia_mode = attr->ia_mode;
805 }
806 if (attr->ia_valid & ATTR_UID) {
807 attrs.ia_valid |= HOSTFS_ATTR_UID;
808 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
809 }
810 if (attr->ia_valid & ATTR_GID) {
811 attrs.ia_valid |= HOSTFS_ATTR_GID;
812 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
813 }
814 if (attr->ia_valid & ATTR_SIZE) {
815 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
816 attrs.ia_size = attr->ia_size;
817 }
818 if (attr->ia_valid & ATTR_ATIME) {
819 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
820 attrs.ia_atime = (struct hostfs_timespec)
821 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec };
822 }
823 if (attr->ia_valid & ATTR_MTIME) {
824 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
825 attrs.ia_mtime = (struct hostfs_timespec)
826 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec };
827 }
828 if (attr->ia_valid & ATTR_CTIME) {
829 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
830 attrs.ia_ctime = (struct hostfs_timespec)
831 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec };
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_rename2,
871 .permission = hostfs_permission,
872 .setattr = hostfs_setattr,
873 };
874
875 static const char *hostfs_get_link(struct dentry *dentry,
876 struct inode *inode,
877 struct delayed_call *done)
878 {
879 char *link;
880 if (!dentry)
881 return ERR_PTR(-ECHILD);
882 link = kmalloc(PATH_MAX, GFP_KERNEL);
883 if (link) {
884 char *path = dentry_name(dentry);
885 int err = -ENOMEM;
886 if (path) {
887 err = hostfs_do_readlink(path, link, PATH_MAX);
888 if (err == PATH_MAX)
889 err = -E2BIG;
890 __putname(path);
891 }
892 if (err < 0) {
893 kfree(link);
894 return ERR_PTR(err);
895 }
896 } else {
897 return ERR_PTR(-ENOMEM);
898 }
899
900 set_delayed_call(done, kfree_link, link);
901 return link;
902 }
903
904 static const struct inode_operations hostfs_link_iops = {
905 .get_link = hostfs_get_link,
906 };
907
908 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
909 {
910 struct inode *root_inode;
911 char *host_root_path, *req_root = d;
912 int err;
913
914 sb->s_blocksize = 1024;
915 sb->s_blocksize_bits = 10;
916 sb->s_magic = HOSTFS_SUPER_MAGIC;
917 sb->s_op = &hostfs_sbops;
918 sb->s_d_op = &simple_dentry_operations;
919 sb->s_maxbytes = MAX_LFS_FILESIZE;
920
921 /* NULL is printed as '(null)' by printf(): avoid that. */
922 if (req_root == NULL)
923 req_root = "";
924
925 err = -ENOMEM;
926 sb->s_fs_info = host_root_path =
927 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root);
928 if (host_root_path == NULL)
929 goto out;
930
931 root_inode = new_inode(sb);
932 if (!root_inode)
933 goto out;
934
935 err = read_name(root_inode, host_root_path);
936 if (err)
937 goto out_put;
938
939 if (S_ISLNK(root_inode->i_mode)) {
940 char *name = follow_link(host_root_path);
941 if (IS_ERR(name)) {
942 err = PTR_ERR(name);
943 goto out_put;
944 }
945 err = read_name(root_inode, name);
946 kfree(name);
947 if (err)
948 goto out_put;
949 }
950
951 err = -ENOMEM;
952 sb->s_root = d_make_root(root_inode);
953 if (sb->s_root == NULL)
954 goto out;
955
956 return 0;
957
958 out_put:
959 iput(root_inode);
960 out:
961 return err;
962 }
963
964 static struct dentry *hostfs_read_sb(struct file_system_type *type,
965 int flags, const char *dev_name,
966 void *data)
967 {
968 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
969 }
970
971 static void hostfs_kill_sb(struct super_block *s)
972 {
973 kill_anon_super(s);
974 kfree(s->s_fs_info);
975 }
976
977 static struct file_system_type hostfs_type = {
978 .owner = THIS_MODULE,
979 .name = "hostfs",
980 .mount = hostfs_read_sb,
981 .kill_sb = hostfs_kill_sb,
982 .fs_flags = 0,
983 };
984 MODULE_ALIAS_FS("hostfs");
985
986 static int __init init_hostfs(void)
987 {
988 return register_filesystem(&hostfs_type);
989 }
990
991 static void __exit exit_hostfs(void)
992 {
993 unregister_filesystem(&hostfs_type);
994 }
995
996 module_init(init_hostfs)
997 module_exit(exit_hostfs)
998 MODULE_LICENSE("GPL");
999
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
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