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gro: Allow tunnel stacking in the case of FOU/GUE
[linux/fpc-iii.git] / fs / hostfs / hostfs_kern.c
blob81ce4e4ad0f97bc70491caa4bc4450b9e3f1e799
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 int len, n;
143 char *name, *resolved, *end;
144
145 name = __getname();
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 len = strlen(link) + strlen(name) + 1;
168
169 resolved = kmalloc(len, GFP_KERNEL);
170 if (resolved == NULL) {
171 n = -ENOMEM;
172 goto out_free;
173 }
174
175 sprintf(resolved, "%s%s", link, name);
176 __putname(name);
177 kfree(link);
178 return resolved;
179
180 out_free:
181 __putname(name);
182 return ERR_PTR(n);
183 }
184
185 static struct inode *hostfs_iget(struct super_block *sb)
186 {
187 struct inode *inode = new_inode(sb);
188 if (!inode)
189 return ERR_PTR(-ENOMEM);
190 return inode;
191 }
192
193 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
194 {
195 /*
196 * do_statfs uses struct statfs64 internally, but the linux kernel
197 * struct statfs still has 32-bit versions for most of these fields,
198 * so we convert them here
199 */
200 int err;
201 long long f_blocks;
202 long long f_bfree;
203 long long f_bavail;
204 long long f_files;
205 long long f_ffree;
206
207 err = do_statfs(dentry->d_sb->s_fs_info,
208 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
209 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
210 &sf->f_namelen);
211 if (err)
212 return err;
213 sf->f_blocks = f_blocks;
214 sf->f_bfree = f_bfree;
215 sf->f_bavail = f_bavail;
216 sf->f_files = f_files;
217 sf->f_ffree = f_ffree;
218 sf->f_type = HOSTFS_SUPER_MAGIC;
219 return 0;
220 }
221
222 static struct inode *hostfs_alloc_inode(struct super_block *sb)
223 {
224 struct hostfs_inode_info *hi;
225
226 hi = kmalloc(sizeof(*hi), GFP_KERNEL);
227 if (hi == NULL)
228 return NULL;
229 hi->fd = -1;
230 hi->mode = 0;
231 inode_init_once(&hi->vfs_inode);
232 mutex_init(&hi->open_mutex);
233 return &hi->vfs_inode;
234 }
235
236 static void hostfs_evict_inode(struct inode *inode)
237 {
238 truncate_inode_pages_final(&inode->i_data);
239 clear_inode(inode);
240 if (HOSTFS_I(inode)->fd != -1) {
241 close_file(&HOSTFS_I(inode)->fd);
242 HOSTFS_I(inode)->fd = -1;
243 }
244 }
245
246 static void hostfs_i_callback(struct rcu_head *head)
247 {
248 struct inode *inode = container_of(head, struct inode, i_rcu);
249 kfree(HOSTFS_I(inode));
250 }
251
252 static void hostfs_destroy_inode(struct inode *inode)
253 {
254 call_rcu(&inode->i_rcu, hostfs_i_callback);
255 }
256
257 static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
258 {
259 const char *root_path = root->d_sb->s_fs_info;
260 size_t offset = strlen(root_ino) + 1;
261
262 if (strlen(root_path) > offset)
263 seq_show_option(seq, root_path + offset, NULL);
264
265 if (append)
266 seq_puts(seq, ",append");
267
268 return 0;
269 }
270
271 static const struct super_operations hostfs_sbops = {
272 .alloc_inode = hostfs_alloc_inode,
273 .destroy_inode = hostfs_destroy_inode,
274 .evict_inode = hostfs_evict_inode,
275 .statfs = hostfs_statfs,
276 .show_options = hostfs_show_options,
277 };
278
279 static int hostfs_readdir(struct file *file, struct dir_context *ctx)
280 {
281 void *dir;
282 char *name;
283 unsigned long long next, ino;
284 int error, len;
285 unsigned int type;
286
287 name = dentry_name(file->f_path.dentry);
288 if (name == NULL)
289 return -ENOMEM;
290 dir = open_dir(name, &error);
291 __putname(name);
292 if (dir == NULL)
293 return -error;
294 next = ctx->pos;
295 seek_dir(dir, next);
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 static int hostfs_open(struct inode *ino, struct file *file)
306 {
307 char *name;
308 fmode_t mode;
309 int err;
310 int r, w, fd;
311
312 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
313 if ((mode & HOSTFS_I(ino)->mode) == mode)
314 return 0;
315
316 mode |= HOSTFS_I(ino)->mode;
317
318 retry:
319 r = w = 0;
320
321 if (mode & FMODE_READ)
322 r = 1;
323 if (mode & FMODE_WRITE)
324 r = w = 1;
325
326 name = dentry_name(file->f_path.dentry);
327 if (name == NULL)
328 return -ENOMEM;
329
330 fd = open_file(name, r, w, append);
331 __putname(name);
332 if (fd < 0)
333 return fd;
334
335 mutex_lock(&HOSTFS_I(ino)->open_mutex);
336 /* somebody else had handled it first? */
337 if ((mode & HOSTFS_I(ino)->mode) == mode) {
338 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
339 close_file(&fd);
340 return 0;
341 }
342 if ((mode | HOSTFS_I(ino)->mode) != mode) {
343 mode |= HOSTFS_I(ino)->mode;
344 mutex_unlock(&HOSTFS_I(ino)->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(&HOSTFS_I(ino)->open_mutex);
355 return err;
356 }
357 }
358 HOSTFS_I(ino)->mode = mode;
359 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
360
361 return 0;
362 }
363
364 static int hostfs_file_release(struct inode *inode, struct file *file)
365 {
366 filemap_write_and_wait(inode->i_mapping);
367
368 return 0;
369 }
370
371 static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
372 int datasync)
373 {
374 struct inode *inode = file->f_mapping->host;
375 int ret;
376
377 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
378 if (ret)
379 return ret;
380
381 mutex_lock(&inode->i_mutex);
382 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
383 mutex_unlock(&inode->i_mutex);
384
385 return ret;
386 }
387
388 static const struct file_operations hostfs_file_fops = {
389 .llseek = generic_file_llseek,
390 .splice_read = generic_file_splice_read,
391 .read_iter = generic_file_read_iter,
392 .write_iter = generic_file_write_iter,
393 .mmap = generic_file_mmap,
394 .open = hostfs_open,
395 .release = hostfs_file_release,
396 .fsync = hostfs_fsync,
397 };
398
399 static const struct file_operations hostfs_dir_fops = {
400 .llseek = generic_file_llseek,
401 .iterate = hostfs_readdir,
402 .read = generic_read_dir,
403 .open = hostfs_open,
404 .fsync = hostfs_fsync,
405 };
406
407 static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
408 {
409 struct address_space *mapping = page->mapping;
410 struct inode *inode = mapping->host;
411 char *buffer;
412 loff_t base = page_offset(page);
413 int count = PAGE_CACHE_SIZE;
414 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
415 int err;
416
417 if (page->index >= end_index)
418 count = inode->i_size & (PAGE_CACHE_SIZE-1);
419
420 buffer = kmap(page);
421
422 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
423 if (err != count) {
424 ClearPageUptodate(page);
425 goto out;
426 }
427
428 if (base > inode->i_size)
429 inode->i_size = base;
430
431 if (PageError(page))
432 ClearPageError(page);
433 err = 0;
434
435 out:
436 kunmap(page);
437
438 unlock_page(page);
439 return err;
440 }
441
442 static int hostfs_readpage(struct file *file, struct page *page)
443 {
444 char *buffer;
445 loff_t start = page_offset(page);
446 int bytes_read, ret = 0;
447
448 buffer = kmap(page);
449 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
450 PAGE_CACHE_SIZE);
451 if (bytes_read < 0) {
452 ClearPageUptodate(page);
453 SetPageError(page);
454 ret = bytes_read;
455 goto out;
456 }
457
458 memset(buffer + bytes_read, 0, PAGE_CACHE_SIZE - bytes_read);
459
460 ClearPageError(page);
461 SetPageUptodate(page);
462
463 out:
464 flush_dcache_page(page);
465 kunmap(page);
466 unlock_page(page);
467 return ret;
468 }
469
470 static int hostfs_write_begin(struct file *file, struct address_space *mapping,
471 loff_t pos, unsigned len, unsigned flags,
472 struct page **pagep, void **fsdata)
473 {
474 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
475
476 *pagep = grab_cache_page_write_begin(mapping, index, flags);
477 if (!*pagep)
478 return -ENOMEM;
479 return 0;
480 }
481
482 static int hostfs_write_end(struct file *file, struct address_space *mapping,
483 loff_t pos, unsigned len, unsigned copied,
484 struct page *page, void *fsdata)
485 {
486 struct inode *inode = mapping->host;
487 void *buffer;
488 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
489 int err;
490
491 buffer = kmap(page);
492 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
493 kunmap(page);
494
495 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
496 SetPageUptodate(page);
497
498 /*
499 * If err > 0, write_file has added err to pos, so we are comparing
500 * i_size against the last byte written.
501 */
502 if (err > 0 && (pos > inode->i_size))
503 inode->i_size = pos;
504 unlock_page(page);
505 page_cache_release(page);
506
507 return err;
508 }
509
510 static const struct address_space_operations hostfs_aops = {
511 .writepage = hostfs_writepage,
512 .readpage = hostfs_readpage,
513 .set_page_dirty = __set_page_dirty_nobuffers,
514 .write_begin = hostfs_write_begin,
515 .write_end = hostfs_write_end,
516 };
517
518 static int read_name(struct inode *ino, char *name)
519 {
520 dev_t rdev;
521 struct hostfs_stat st;
522 int err = stat_file(name, &st, -1);
523 if (err)
524 return err;
525
526 /* Reencode maj and min with the kernel encoding.*/
527 rdev = MKDEV(st.maj, st.min);
528
529 switch (st.mode & S_IFMT) {
530 case S_IFLNK:
531 ino->i_op = &hostfs_link_iops;
532 break;
533 case S_IFDIR:
534 ino->i_op = &hostfs_dir_iops;
535 ino->i_fop = &hostfs_dir_fops;
536 break;
537 case S_IFCHR:
538 case S_IFBLK:
539 case S_IFIFO:
540 case S_IFSOCK:
541 init_special_inode(ino, st.mode & S_IFMT, rdev);
542 ino->i_op = &hostfs_iops;
543 break;
544 case S_IFREG:
545 ino->i_op = &hostfs_iops;
546 ino->i_fop = &hostfs_file_fops;
547 ino->i_mapping->a_ops = &hostfs_aops;
548 break;
549 default:
550 return -EIO;
551 }
552
553 ino->i_ino = st.ino;
554 ino->i_mode = st.mode;
555 set_nlink(ino, st.nlink);
556 i_uid_write(ino, st.uid);
557 i_gid_write(ino, st.gid);
558 ino->i_atime = st.atime;
559 ino->i_mtime = st.mtime;
560 ino->i_ctime = st.ctime;
561 ino->i_size = st.size;
562 ino->i_blocks = st.blocks;
563 return 0;
564 }
565
566 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
567 bool excl)
568 {
569 struct inode *inode;
570 char *name;
571 int error, fd;
572
573 inode = hostfs_iget(dir->i_sb);
574 if (IS_ERR(inode)) {
575 error = PTR_ERR(inode);
576 goto out;
577 }
578
579 error = -ENOMEM;
580 name = dentry_name(dentry);
581 if (name == NULL)
582 goto out_put;
583
584 fd = file_create(name, mode & 0777);
585 if (fd < 0)
586 error = fd;
587 else
588 error = read_name(inode, name);
589
590 __putname(name);
591 if (error)
592 goto out_put;
593
594 HOSTFS_I(inode)->fd = fd;
595 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
596 d_instantiate(dentry, inode);
597 return 0;
598
599 out_put:
600 iput(inode);
601 out:
602 return error;
603 }
604
605 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
606 unsigned int flags)
607 {
608 struct inode *inode;
609 char *name;
610 int err;
611
612 inode = hostfs_iget(ino->i_sb);
613 if (IS_ERR(inode)) {
614 err = PTR_ERR(inode);
615 goto out;
616 }
617
618 err = -ENOMEM;
619 name = dentry_name(dentry);
620 if (name == NULL)
621 goto out_put;
622
623 err = read_name(inode, name);
624
625 __putname(name);
626 if (err == -ENOENT) {
627 iput(inode);
628 inode = NULL;
629 }
630 else if (err)
631 goto out_put;
632
633 d_add(dentry, inode);
634 return NULL;
635
636 out_put:
637 iput(inode);
638 out:
639 return ERR_PTR(err);
640 }
641
642 static int hostfs_link(struct dentry *to, struct inode *ino,
643 struct dentry *from)
644 {
645 char *from_name, *to_name;
646 int err;
647
648 if ((from_name = dentry_name(from)) == NULL)
649 return -ENOMEM;
650 to_name = dentry_name(to);
651 if (to_name == NULL) {
652 __putname(from_name);
653 return -ENOMEM;
654 }
655 err = link_file(to_name, from_name);
656 __putname(from_name);
657 __putname(to_name);
658 return err;
659 }
660
661 static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
662 {
663 char *file;
664 int err;
665
666 if (append)
667 return -EPERM;
668
669 if ((file = dentry_name(dentry)) == NULL)
670 return -ENOMEM;
671
672 err = unlink_file(file);
673 __putname(file);
674 return err;
675 }
676
677 static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
678 const char *to)
679 {
680 char *file;
681 int err;
682
683 if ((file = dentry_name(dentry)) == NULL)
684 return -ENOMEM;
685 err = make_symlink(file, to);
686 __putname(file);
687 return err;
688 }
689
690 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
691 {
692 char *file;
693 int err;
694
695 if ((file = dentry_name(dentry)) == NULL)
696 return -ENOMEM;
697 err = do_mkdir(file, mode);
698 __putname(file);
699 return err;
700 }
701
702 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
703 {
704 char *file;
705 int err;
706
707 if ((file = dentry_name(dentry)) == NULL)
708 return -ENOMEM;
709 err = do_rmdir(file);
710 __putname(file);
711 return err;
712 }
713
714 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
715 {
716 struct inode *inode;
717 char *name;
718 int err;
719
720 inode = hostfs_iget(dir->i_sb);
721 if (IS_ERR(inode)) {
722 err = PTR_ERR(inode);
723 goto out;
724 }
725
726 err = -ENOMEM;
727 name = dentry_name(dentry);
728 if (name == NULL)
729 goto out_put;
730
731 init_special_inode(inode, mode, dev);
732 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
733 if (err)
734 goto out_free;
735
736 err = read_name(inode, name);
737 __putname(name);
738 if (err)
739 goto out_put;
740
741 d_instantiate(dentry, inode);
742 return 0;
743
744 out_free:
745 __putname(name);
746 out_put:
747 iput(inode);
748 out:
749 return err;
750 }
751
752 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
753 struct inode *new_dir, struct dentry *new_dentry,
754 unsigned int flags)
755 {
756 char *old_name, *new_name;
757 int err;
758
759 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
760 return -EINVAL;
761
762 old_name = dentry_name(old_dentry);
763 if (old_name == NULL)
764 return -ENOMEM;
765 new_name = dentry_name(new_dentry);
766 if (new_name == NULL) {
767 __putname(old_name);
768 return -ENOMEM;
769 }
770 if (!flags)
771 err = rename_file(old_name, new_name);
772 else
773 err = rename2_file(old_name, new_name, flags);
774
775 __putname(old_name);
776 __putname(new_name);
777 return err;
778 }
779
780 static int hostfs_permission(struct inode *ino, int desired)
781 {
782 char *name;
783 int r = 0, w = 0, x = 0, err;
784
785 if (desired & MAY_NOT_BLOCK)
786 return -ECHILD;
787
788 if (desired & MAY_READ) r = 1;
789 if (desired & MAY_WRITE) w = 1;
790 if (desired & MAY_EXEC) x = 1;
791 name = inode_name(ino);
792 if (name == NULL)
793 return -ENOMEM;
794
795 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
796 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
797 err = 0;
798 else
799 err = access_file(name, r, w, x);
800 __putname(name);
801 if (!err)
802 err = generic_permission(ino, desired);
803 return err;
804 }
805
806 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
807 {
808 struct inode *inode = d_inode(dentry);
809 struct hostfs_iattr attrs;
810 char *name;
811 int err;
812
813 int fd = HOSTFS_I(inode)->fd;
814
815 err = setattr_prepare(dentry, attr);
816 if (err)
817 return err;
818
819 if (append)
820 attr->ia_valid &= ~ATTR_SIZE;
821
822 attrs.ia_valid = 0;
823 if (attr->ia_valid & ATTR_MODE) {
824 attrs.ia_valid |= HOSTFS_ATTR_MODE;
825 attrs.ia_mode = attr->ia_mode;
826 }
827 if (attr->ia_valid & ATTR_UID) {
828 attrs.ia_valid |= HOSTFS_ATTR_UID;
829 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
830 }
831 if (attr->ia_valid & ATTR_GID) {
832 attrs.ia_valid |= HOSTFS_ATTR_GID;
833 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
834 }
835 if (attr->ia_valid & ATTR_SIZE) {
836 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
837 attrs.ia_size = attr->ia_size;
838 }
839 if (attr->ia_valid & ATTR_ATIME) {
840 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
841 attrs.ia_atime = attr->ia_atime;
842 }
843 if (attr->ia_valid & ATTR_MTIME) {
844 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
845 attrs.ia_mtime = attr->ia_mtime;
846 }
847 if (attr->ia_valid & ATTR_CTIME) {
848 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
849 attrs.ia_ctime = attr->ia_ctime;
850 }
851 if (attr->ia_valid & ATTR_ATIME_SET) {
852 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
853 }
854 if (attr->ia_valid & ATTR_MTIME_SET) {
855 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
856 }
857 name = dentry_name(dentry);
858 if (name == NULL)
859 return -ENOMEM;
860 err = set_attr(name, &attrs, fd);
861 __putname(name);
862 if (err)
863 return err;
864
865 if ((attr->ia_valid & ATTR_SIZE) &&
866 attr->ia_size != i_size_read(inode))
867 truncate_setsize(inode, attr->ia_size);
868
869 setattr_copy(inode, attr);
870 mark_inode_dirty(inode);
871 return 0;
872 }
873
874 static const struct inode_operations hostfs_iops = {
875 .permission = hostfs_permission,
876 .setattr = hostfs_setattr,
877 };
878
879 static const struct inode_operations hostfs_dir_iops = {
880 .create = hostfs_create,
881 .lookup = hostfs_lookup,
882 .link = hostfs_link,
883 .unlink = hostfs_unlink,
884 .symlink = hostfs_symlink,
885 .mkdir = hostfs_mkdir,
886 .rmdir = hostfs_rmdir,
887 .mknod = hostfs_mknod,
888 .rename2 = hostfs_rename2,
889 .permission = hostfs_permission,
890 .setattr = hostfs_setattr,
891 };
892
893 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
894 {
895 char *link = __getname();
896 if (link) {
897 char *path = dentry_name(dentry);
898 int err = -ENOMEM;
899 if (path) {
900 err = hostfs_do_readlink(path, link, PATH_MAX);
901 if (err == PATH_MAX)
902 err = -E2BIG;
903 __putname(path);
904 }
905 if (err < 0) {
906 __putname(link);
907 link = ERR_PTR(err);
908 }
909 } else {
910 link = ERR_PTR(-ENOMEM);
911 }
912
913 nd_set_link(nd, link);
914 return NULL;
915 }
916
917 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
918 {
919 char *s = nd_get_link(nd);
920 if (!IS_ERR(s))
921 __putname(s);
922 }
923
924 static const struct inode_operations hostfs_link_iops = {
925 .readlink = generic_readlink,
926 .follow_link = hostfs_follow_link,
927 .put_link = hostfs_put_link,
928 };
929
930 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
931 {
932 struct inode *root_inode;
933 char *host_root_path, *req_root = d;
934 int err;
935
936 sb->s_blocksize = 1024;
937 sb->s_blocksize_bits = 10;
938 sb->s_magic = HOSTFS_SUPER_MAGIC;
939 sb->s_op = &hostfs_sbops;
940 sb->s_d_op = &simple_dentry_operations;
941 sb->s_maxbytes = MAX_LFS_FILESIZE;
942
943 /* NULL is printed as <NULL> by sprintf: avoid that. */
944 if (req_root == NULL)
945 req_root = "";
946
947 err = -ENOMEM;
948 sb->s_fs_info = host_root_path =
949 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
950 if (host_root_path == NULL)
951 goto out;
952
953 sprintf(host_root_path, "%s/%s", root_ino, req_root);
954
955 root_inode = new_inode(sb);
956 if (!root_inode)
957 goto out;
958
959 err = read_name(root_inode, host_root_path);
960 if (err)
961 goto out_put;
962
963 if (S_ISLNK(root_inode->i_mode)) {
964 char *name = follow_link(host_root_path);
965 if (IS_ERR(name))
966 err = PTR_ERR(name);
967 else
968 err = read_name(root_inode, name);
969 kfree(name);
970 if (err)
971 goto out_put;
972 }
973
974 err = -ENOMEM;
975 sb->s_root = d_make_root(root_inode);
976 if (sb->s_root == NULL)
977 goto out;
978
979 return 0;
980
981 out_put:
982 iput(root_inode);
983 out:
984 return err;
985 }
986
987 static struct dentry *hostfs_read_sb(struct file_system_type *type,
988 int flags, const char *dev_name,
989 void *data)
990 {
991 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
992 }
993
994 static void hostfs_kill_sb(struct super_block *s)
995 {
996 kill_anon_super(s);
997 kfree(s->s_fs_info);
998 }
999
1000 static struct file_system_type hostfs_type = {
1001 .owner = THIS_MODULE,
1002 .name = "hostfs",
1003 .mount = hostfs_read_sb,
1004 .kill_sb = hostfs_kill_sb,
1005 .fs_flags = 0,
1006 };
1007 MODULE_ALIAS_FS("hostfs");
1008
1009 static int __init init_hostfs(void)
1010 {
1011 return register_filesystem(&hostfs_type);
1012 }
1013
1014 static void __exit exit_hostfs(void)
1015 {
1016 unregister_filesystem(&hostfs_type);
1017 }
1018
1019 module_init(init_hostfs)
1020 module_exit(exit_hostfs)
1021 MODULE_LICENSE("GPL");
Linux with added FPC-III support