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Linux 3.12.28
[linux/fpc-iii.git] / fs / hostfs / hostfs_kern.c
blob25437280a2071b8970efe6e394edb97a4433acd8
1 /*
2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 *
5 * Ported the filesystem routines to 2.5.
6 * 2003-02-10 Petr Baudis <pasky@ucw.cz>
7 */
8
9 #include <linux/fs.h>
10 #include <linux/magic.h>
11 #include <linux/module.h>
12 #include <linux/mm.h>
13 #include <linux/pagemap.h>
14 #include <linux/statfs.h>
15 #include <linux/slab.h>
16 #include <linux/seq_file.h>
17 #include <linux/mount.h>
18 #include <linux/namei.h>
19 #include "hostfs.h"
20 #include <init.h>
21 #include <kern.h>
22
23 struct hostfs_inode_info {
24 int fd;
25 fmode_t mode;
26 struct inode vfs_inode;
27 };
28
29 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
30 {
31 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
32 }
33
34 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file))
35
36 static int hostfs_d_delete(const struct dentry *dentry)
37 {
38 return 1;
39 }
40
41 static const struct dentry_operations hostfs_dentry_ops = {
42 .d_delete = hostfs_d_delete,
43 };
44
45 /* Changed in hostfs_args before the kernel starts running */
46 static char *root_ino = "";
47 static int append = 0;
48
49 static const struct inode_operations hostfs_iops;
50 static const struct inode_operations hostfs_dir_iops;
51 static const struct inode_operations hostfs_link_iops;
52
53 #ifndef MODULE
54 static int __init hostfs_args(char *options, int *add)
55 {
56 char *ptr;
57
58 ptr = strchr(options, ',');
59 if (ptr != NULL)
60 *ptr++ = '\0';
61 if (*options != '\0')
62 root_ino = options;
63
64 options = ptr;
65 while (options) {
66 ptr = strchr(options, ',');
67 if (ptr != NULL)
68 *ptr++ = '\0';
69 if (*options != '\0') {
70 if (!strcmp(options, "append"))
71 append = 1;
72 else printf("hostfs_args - unsupported option - %s\n",
73 options);
74 }
75 options = ptr;
76 }
77 return 0;
78 }
79
80 __uml_setup("hostfs=", hostfs_args,
81 "hostfs=<root dir>,<flags>,...\n"
82 " This is used to set hostfs parameters. The root directory argument\n"
83 " is used to confine all hostfs mounts to within the specified directory\n"
84 " tree on the host. If this isn't specified, then a user inside UML can\n"
85 " mount anything on the host that's accessible to the user that's running\n"
86 " it.\n"
87 " The only flag currently supported is 'append', which specifies that all\n"
88 " files opened by hostfs will be opened in append mode.\n\n"
89 );
90 #endif
91
92 static char *__dentry_name(struct dentry *dentry, char *name)
93 {
94 char *p = dentry_path_raw(dentry, name, PATH_MAX);
95 char *root;
96 size_t len;
97
98 root = dentry->d_sb->s_fs_info;
99 len = strlen(root);
100 if (IS_ERR(p)) {
101 __putname(name);
102 return NULL;
103 }
104 strlcpy(name, root, PATH_MAX);
105 if (len > p - name) {
106 __putname(name);
107 return NULL;
108 }
109 if (p > name + len) {
110 char *s = name + len;
111 while ((*s++ = *p++) != '\0')
112 ;
113 }
114 return name;
115 }
116
117 static char *dentry_name(struct dentry *dentry)
118 {
119 char *name = __getname();
120 if (!name)
121 return NULL;
122
123 return __dentry_name(dentry, name);
124 }
125
126 static char *inode_name(struct inode *ino)
127 {
128 struct dentry *dentry;
129 char *name;
130
131 dentry = d_find_alias(ino);
132 if (!dentry)
133 return NULL;
134
135 name = dentry_name(dentry);
136
137 dput(dentry);
138
139 return name;
140 }
141
142 static char *follow_link(char *link)
143 {
144 int len, n;
145 char *name, *resolved, *end;
146
147 len = 64;
148 while (1) {
149 n = -ENOMEM;
150 name = kmalloc(len, GFP_KERNEL);
151 if (name == NULL)
152 goto out;
153
154 n = hostfs_do_readlink(link, name, len);
155 if (n < len)
156 break;
157 len *= 2;
158 kfree(name);
159 }
160 if (n < 0)
161 goto out_free;
162
163 if (*name == '/')
164 return name;
165
166 end = strrchr(link, '/');
167 if (end == NULL)
168 return name;
169
170 *(end + 1) = '\0';
171 len = strlen(link) + strlen(name) + 1;
172
173 resolved = kmalloc(len, GFP_KERNEL);
174 if (resolved == NULL) {
175 n = -ENOMEM;
176 goto out_free;
177 }
178
179 sprintf(resolved, "%s%s", link, name);
180 kfree(name);
181 kfree(link);
182 return resolved;
183
184 out_free:
185 kfree(name);
186 out:
187 return ERR_PTR(n);
188 }
189
190 static struct inode *hostfs_iget(struct super_block *sb)
191 {
192 struct inode *inode = new_inode(sb);
193 if (!inode)
194 return ERR_PTR(-ENOMEM);
195 return inode;
196 }
197
198 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
199 {
200 /*
201 * do_statfs uses struct statfs64 internally, but the linux kernel
202 * struct statfs still has 32-bit versions for most of these fields,
203 * so we convert them here
204 */
205 int err;
206 long long f_blocks;
207 long long f_bfree;
208 long long f_bavail;
209 long long f_files;
210 long long f_ffree;
211
212 err = do_statfs(dentry->d_sb->s_fs_info,
213 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
214 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
215 &sf->f_namelen);
216 if (err)
217 return err;
218 sf->f_blocks = f_blocks;
219 sf->f_bfree = f_bfree;
220 sf->f_bavail = f_bavail;
221 sf->f_files = f_files;
222 sf->f_ffree = f_ffree;
223 sf->f_type = HOSTFS_SUPER_MAGIC;
224 return 0;
225 }
226
227 static struct inode *hostfs_alloc_inode(struct super_block *sb)
228 {
229 struct hostfs_inode_info *hi;
230
231 hi = kmalloc(sizeof(*hi), GFP_KERNEL);
232 if (hi == NULL)
233 return NULL;
234 hi->fd = -1;
235 hi->mode = 0;
236 inode_init_once(&hi->vfs_inode);
237 return &hi->vfs_inode;
238 }
239
240 static void hostfs_evict_inode(struct inode *inode)
241 {
242 truncate_inode_pages(&inode->i_data, 0);
243 clear_inode(inode);
244 if (HOSTFS_I(inode)->fd != -1) {
245 close_file(&HOSTFS_I(inode)->fd);
246 HOSTFS_I(inode)->fd = -1;
247 }
248 }
249
250 static void hostfs_i_callback(struct rcu_head *head)
251 {
252 struct inode *inode = container_of(head, struct inode, i_rcu);
253 kfree(HOSTFS_I(inode));
254 }
255
256 static void hostfs_destroy_inode(struct inode *inode)
257 {
258 call_rcu(&inode->i_rcu, hostfs_i_callback);
259 }
260
261 static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
262 {
263 const char *root_path = root->d_sb->s_fs_info;
264 size_t offset = strlen(root_ino) + 1;
265
266 if (strlen(root_path) > offset)
267 seq_printf(seq, ",%s", root_path + offset);
268
269 return 0;
270 }
271
272 static const struct super_operations hostfs_sbops = {
273 .alloc_inode = hostfs_alloc_inode,
274 .destroy_inode = hostfs_destroy_inode,
275 .evict_inode = hostfs_evict_inode,
276 .statfs = hostfs_statfs,
277 .show_options = hostfs_show_options,
278 };
279
280 int hostfs_readdir(struct file *file, struct dir_context *ctx)
281 {
282 void *dir;
283 char *name;
284 unsigned long long next, ino;
285 int error, len;
286 unsigned int type;
287
288 name = dentry_name(file->f_path.dentry);
289 if (name == NULL)
290 return -ENOMEM;
291 dir = open_dir(name, &error);
292 __putname(name);
293 if (dir == NULL)
294 return -error;
295 next = ctx->pos;
296 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
297 if (!dir_emit(ctx, name, len, ino, type))
298 break;
299 ctx->pos = next;
300 }
301 close_dir(dir);
302 return 0;
303 }
304
305 int hostfs_file_open(struct inode *ino, struct file *file)
306 {
307 static DEFINE_MUTEX(open_mutex);
308 char *name;
309 fmode_t mode = 0;
310 int err;
311 int r = 0, w = 0, fd;
312
313 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
314 if ((mode & HOSTFS_I(ino)->mode) == mode)
315 return 0;
316
317 mode |= HOSTFS_I(ino)->mode;
318
319 retry:
320 if (mode & FMODE_READ)
321 r = 1;
322 if (mode & FMODE_WRITE)
323 w = 1;
324 if (w)
325 r = 1;
326
327 name = dentry_name(file->f_path.dentry);
328 if (name == NULL)
329 return -ENOMEM;
330
331 fd = open_file(name, r, w, append);
332 __putname(name);
333 if (fd < 0)
334 return fd;
335
336 mutex_lock(&open_mutex);
337 /* somebody else had handled it first? */
338 if ((mode & HOSTFS_I(ino)->mode) == mode) {
339 mutex_unlock(&open_mutex);
340 return 0;
341 }
342 if ((mode | HOSTFS_I(ino)->mode) != mode) {
343 mode |= HOSTFS_I(ino)->mode;
344 mutex_unlock(&open_mutex);
345 close_file(&fd);
346 goto retry;
347 }
348 if (HOSTFS_I(ino)->fd == -1) {
349 HOSTFS_I(ino)->fd = fd;
350 } else {
351 err = replace_file(fd, HOSTFS_I(ino)->fd);
352 close_file(&fd);
353 if (err < 0) {
354 mutex_unlock(&open_mutex);
355 return err;
356 }
357 }
358 HOSTFS_I(ino)->mode = mode;
359 mutex_unlock(&open_mutex);
360
361 return 0;
362 }
363
364 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 int hostfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
372 {
373 struct inode *inode = file->f_mapping->host;
374 int ret;
375
376 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
377 if (ret)
378 return ret;
379
380 mutex_lock(&inode->i_mutex);
381 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
382 mutex_unlock(&inode->i_mutex);
383
384 return ret;
385 }
386
387 static const struct file_operations hostfs_file_fops = {
388 .llseek = generic_file_llseek,
389 .read = do_sync_read,
390 .splice_read = generic_file_splice_read,
391 .aio_read = generic_file_aio_read,
392 .aio_write = generic_file_aio_write,
393 .write = do_sync_write,
394 .mmap = generic_file_mmap,
395 .open = hostfs_file_open,
396 .release = hostfs_file_release,
397 .fsync = hostfs_fsync,
398 };
399
400 static const struct file_operations hostfs_dir_fops = {
401 .llseek = generic_file_llseek,
402 .iterate = hostfs_readdir,
403 .read = generic_read_dir,
404 };
405
406 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
407 {
408 struct address_space *mapping = page->mapping;
409 struct inode *inode = mapping->host;
410 char *buffer;
411 unsigned long long base;
412 int count = PAGE_CACHE_SIZE;
413 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
414 int err;
415
416 if (page->index >= end_index)
417 count = inode->i_size & (PAGE_CACHE_SIZE-1);
418
419 buffer = kmap(page);
420 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
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 int hostfs_readpage(struct file *file, struct page *page)
443 {
444 char *buffer;
445 long long start;
446 int err = 0;
447
448 start = (long long) page->index << PAGE_CACHE_SHIFT;
449 buffer = kmap(page);
450 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
451 PAGE_CACHE_SIZE);
452 if (err < 0)
453 goto out;
454
455 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
456
457 flush_dcache_page(page);
458 SetPageUptodate(page);
459 if (PageError(page)) ClearPageError(page);
460 err = 0;
461 out:
462 kunmap(page);
463 unlock_page(page);
464 return err;
465 }
466
467 int hostfs_write_begin(struct file *file, struct address_space *mapping,
468 loff_t pos, unsigned len, unsigned flags,
469 struct page **pagep, void **fsdata)
470 {
471 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
472
473 *pagep = grab_cache_page_write_begin(mapping, index, flags);
474 if (!*pagep)
475 return -ENOMEM;
476 return 0;
477 }
478
479 int hostfs_write_end(struct file *file, struct address_space *mapping,
480 loff_t pos, unsigned len, unsigned copied,
481 struct page *page, void *fsdata)
482 {
483 struct inode *inode = mapping->host;
484 void *buffer;
485 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
486 int err;
487
488 buffer = kmap(page);
489 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
490 kunmap(page);
491
492 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
493 SetPageUptodate(page);
494
495 /*
496 * If err > 0, write_file has added err to pos, so we are comparing
497 * i_size against the last byte written.
498 */
499 if (err > 0 && (pos > inode->i_size))
500 inode->i_size = pos;
501 unlock_page(page);
502 page_cache_release(page);
503
504 return err;
505 }
506
507 static const struct address_space_operations hostfs_aops = {
508 .writepage = hostfs_writepage,
509 .readpage = hostfs_readpage,
510 .set_page_dirty = __set_page_dirty_nobuffers,
511 .write_begin = hostfs_write_begin,
512 .write_end = hostfs_write_end,
513 };
514
515 static int read_name(struct inode *ino, char *name)
516 {
517 dev_t rdev;
518 struct hostfs_stat st;
519 int err = stat_file(name, &st, -1);
520 if (err)
521 return err;
522
523 /* Reencode maj and min with the kernel encoding.*/
524 rdev = MKDEV(st.maj, st.min);
525
526 switch (st.mode & S_IFMT) {
527 case S_IFLNK:
528 ino->i_op = &hostfs_link_iops;
529 break;
530 case S_IFDIR:
531 ino->i_op = &hostfs_dir_iops;
532 ino->i_fop = &hostfs_dir_fops;
533 break;
534 case S_IFCHR:
535 case S_IFBLK:
536 case S_IFIFO:
537 case S_IFSOCK:
538 init_special_inode(ino, st.mode & S_IFMT, rdev);
539 ino->i_op = &hostfs_iops;
540 break;
541
542 default:
543 ino->i_op = &hostfs_iops;
544 ino->i_fop = &hostfs_file_fops;
545 ino->i_mapping->a_ops = &hostfs_aops;
546 }
547
548 ino->i_ino = st.ino;
549 ino->i_mode = st.mode;
550 set_nlink(ino, st.nlink);
551 i_uid_write(ino, st.uid);
552 i_gid_write(ino, st.gid);
553 ino->i_atime = st.atime;
554 ino->i_mtime = st.mtime;
555 ino->i_ctime = st.ctime;
556 ino->i_size = st.size;
557 ino->i_blocks = st.blocks;
558 return 0;
559 }
560
561 int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
562 bool excl)
563 {
564 struct inode *inode;
565 char *name;
566 int error, fd;
567
568 inode = hostfs_iget(dir->i_sb);
569 if (IS_ERR(inode)) {
570 error = PTR_ERR(inode);
571 goto out;
572 }
573
574 error = -ENOMEM;
575 name = dentry_name(dentry);
576 if (name == NULL)
577 goto out_put;
578
579 fd = file_create(name,
580 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
581 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
582 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
583 if (fd < 0)
584 error = fd;
585 else
586 error = read_name(inode, name);
587
588 __putname(name);
589 if (error)
590 goto out_put;
591
592 HOSTFS_I(inode)->fd = fd;
593 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
594 d_instantiate(dentry, inode);
595 return 0;
596
597 out_put:
598 iput(inode);
599 out:
600 return error;
601 }
602
603 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
604 unsigned int flags)
605 {
606 struct inode *inode;
607 char *name;
608 int err;
609
610 inode = hostfs_iget(ino->i_sb);
611 if (IS_ERR(inode)) {
612 err = PTR_ERR(inode);
613 goto out;
614 }
615
616 err = -ENOMEM;
617 name = dentry_name(dentry);
618 if (name == NULL)
619 goto out_put;
620
621 err = read_name(inode, name);
622
623 __putname(name);
624 if (err == -ENOENT) {
625 iput(inode);
626 inode = NULL;
627 }
628 else if (err)
629 goto out_put;
630
631 d_add(dentry, inode);
632 return NULL;
633
634 out_put:
635 iput(inode);
636 out:
637 return ERR_PTR(err);
638 }
639
640 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
641 {
642 char *from_name, *to_name;
643 int err;
644
645 if ((from_name = dentry_name(from)) == NULL)
646 return -ENOMEM;
647 to_name = dentry_name(to);
648 if (to_name == NULL) {
649 __putname(from_name);
650 return -ENOMEM;
651 }
652 err = link_file(to_name, from_name);
653 __putname(from_name);
654 __putname(to_name);
655 return err;
656 }
657
658 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
659 {
660 char *file;
661 int err;
662
663 if (append)
664 return -EPERM;
665
666 if ((file = dentry_name(dentry)) == NULL)
667 return -ENOMEM;
668
669 err = unlink_file(file);
670 __putname(file);
671 return err;
672 }
673
674 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
675 {
676 char *file;
677 int err;
678
679 if ((file = dentry_name(dentry)) == NULL)
680 return -ENOMEM;
681 err = make_symlink(file, to);
682 __putname(file);
683 return err;
684 }
685
686 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
687 {
688 char *file;
689 int err;
690
691 if ((file = dentry_name(dentry)) == NULL)
692 return -ENOMEM;
693 err = do_mkdir(file, mode);
694 __putname(file);
695 return err;
696 }
697
698 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
699 {
700 char *file;
701 int err;
702
703 if ((file = dentry_name(dentry)) == NULL)
704 return -ENOMEM;
705 err = do_rmdir(file);
706 __putname(file);
707 return err;
708 }
709
710 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
711 {
712 struct inode *inode;
713 char *name;
714 int err;
715
716 inode = hostfs_iget(dir->i_sb);
717 if (IS_ERR(inode)) {
718 err = PTR_ERR(inode);
719 goto out;
720 }
721
722 err = -ENOMEM;
723 name = dentry_name(dentry);
724 if (name == NULL)
725 goto out_put;
726
727 init_special_inode(inode, mode, dev);
728 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
729 if (!err)
730 goto out_free;
731
732 err = read_name(inode, name);
733 __putname(name);
734 if (err)
735 goto out_put;
736 if (err)
737 goto out_put;
738
739 d_instantiate(dentry, inode);
740 return 0;
741
742 out_free:
743 __putname(name);
744 out_put:
745 iput(inode);
746 out:
747 return err;
748 }
749
750 int hostfs_rename(struct inode *from_ino, struct dentry *from,
751 struct inode *to_ino, struct dentry *to)
752 {
753 char *from_name, *to_name;
754 int err;
755
756 if ((from_name = dentry_name(from)) == NULL)
757 return -ENOMEM;
758 if ((to_name = dentry_name(to)) == NULL) {
759 __putname(from_name);
760 return -ENOMEM;
761 }
762 err = rename_file(from_name, to_name);
763 __putname(from_name);
764 __putname(to_name);
765 return err;
766 }
767
768 int hostfs_permission(struct inode *ino, int desired)
769 {
770 char *name;
771 int r = 0, w = 0, x = 0, err;
772
773 if (desired & MAY_NOT_BLOCK)
774 return -ECHILD;
775
776 if (desired & MAY_READ) r = 1;
777 if (desired & MAY_WRITE) w = 1;
778 if (desired & MAY_EXEC) x = 1;
779 name = inode_name(ino);
780 if (name == NULL)
781 return -ENOMEM;
782
783 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
784 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
785 err = 0;
786 else
787 err = access_file(name, r, w, x);
788 __putname(name);
789 if (!err)
790 err = generic_permission(ino, desired);
791 return err;
792 }
793
794 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
795 {
796 struct inode *inode = dentry->d_inode;
797 struct hostfs_iattr attrs;
798 char *name;
799 int err;
800
801 int fd = HOSTFS_I(inode)->fd;
802
803 err = inode_change_ok(inode, attr);
804 if (err)
805 return err;
806
807 if (append)
808 attr->ia_valid &= ~ATTR_SIZE;
809
810 attrs.ia_valid = 0;
811 if (attr->ia_valid & ATTR_MODE) {
812 attrs.ia_valid |= HOSTFS_ATTR_MODE;
813 attrs.ia_mode = attr->ia_mode;
814 }
815 if (attr->ia_valid & ATTR_UID) {
816 attrs.ia_valid |= HOSTFS_ATTR_UID;
817 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
818 }
819 if (attr->ia_valid & ATTR_GID) {
820 attrs.ia_valid |= HOSTFS_ATTR_GID;
821 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
822 }
823 if (attr->ia_valid & ATTR_SIZE) {
824 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
825 attrs.ia_size = attr->ia_size;
826 }
827 if (attr->ia_valid & ATTR_ATIME) {
828 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
829 attrs.ia_atime = attr->ia_atime;
830 }
831 if (attr->ia_valid & ATTR_MTIME) {
832 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
833 attrs.ia_mtime = attr->ia_mtime;
834 }
835 if (attr->ia_valid & ATTR_CTIME) {
836 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
837 attrs.ia_ctime = attr->ia_ctime;
838 }
839 if (attr->ia_valid & ATTR_ATIME_SET) {
840 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
841 }
842 if (attr->ia_valid & ATTR_MTIME_SET) {
843 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
844 }
845 name = dentry_name(dentry);
846 if (name == NULL)
847 return -ENOMEM;
848 err = set_attr(name, &attrs, fd);
849 __putname(name);
850 if (err)
851 return err;
852
853 if ((attr->ia_valid & ATTR_SIZE) &&
854 attr->ia_size != i_size_read(inode))
855 truncate_setsize(inode, attr->ia_size);
856
857 setattr_copy(inode, attr);
858 mark_inode_dirty(inode);
859 return 0;
860 }
861
862 static const struct inode_operations hostfs_iops = {
863 .permission = hostfs_permission,
864 .setattr = hostfs_setattr,
865 };
866
867 static const struct inode_operations hostfs_dir_iops = {
868 .create = hostfs_create,
869 .lookup = hostfs_lookup,
870 .link = hostfs_link,
871 .unlink = hostfs_unlink,
872 .symlink = hostfs_symlink,
873 .mkdir = hostfs_mkdir,
874 .rmdir = hostfs_rmdir,
875 .mknod = hostfs_mknod,
876 .rename = hostfs_rename,
877 .permission = hostfs_permission,
878 .setattr = hostfs_setattr,
879 };
880
881 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
882 {
883 char *link = __getname();
884 if (link) {
885 char *path = dentry_name(dentry);
886 int err = -ENOMEM;
887 if (path) {
888 err = hostfs_do_readlink(path, link, PATH_MAX);
889 if (err == PATH_MAX)
890 err = -E2BIG;
891 __putname(path);
892 }
893 if (err < 0) {
894 __putname(link);
895 link = ERR_PTR(err);
896 }
897 } else {
898 link = ERR_PTR(-ENOMEM);
899 }
900
901 nd_set_link(nd, link);
902 return NULL;
903 }
904
905 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
906 {
907 char *s = nd_get_link(nd);
908 if (!IS_ERR(s))
909 __putname(s);
910 }
911
912 static const struct inode_operations hostfs_link_iops = {
913 .readlink = generic_readlink,
914 .follow_link = hostfs_follow_link,
915 .put_link = hostfs_put_link,
916 };
917
918 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
919 {
920 struct inode *root_inode;
921 char *host_root_path, *req_root = d;
922 int err;
923
924 sb->s_blocksize = 1024;
925 sb->s_blocksize_bits = 10;
926 sb->s_magic = HOSTFS_SUPER_MAGIC;
927 sb->s_op = &hostfs_sbops;
928 sb->s_d_op = &hostfs_dentry_ops;
929 sb->s_maxbytes = MAX_LFS_FILESIZE;
930
931 /* NULL is printed as <NULL> by sprintf: avoid that. */
932 if (req_root == NULL)
933 req_root = "";
934
935 err = -ENOMEM;
936 sb->s_fs_info = host_root_path =
937 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
938 if (host_root_path == NULL)
939 goto out;
940
941 sprintf(host_root_path, "%s/%s", root_ino, req_root);
942
943 root_inode = new_inode(sb);
944 if (!root_inode)
945 goto out;
946
947 err = read_name(root_inode, host_root_path);
948 if (err)
949 goto out_put;
950
951 if (S_ISLNK(root_inode->i_mode)) {
952 char *name = follow_link(host_root_path);
953 if (IS_ERR(name))
954 err = PTR_ERR(name);
955 else
956 err = read_name(root_inode, name);
957 kfree(name);
958 if (err)
959 goto out_put;
960 }
961
962 err = -ENOMEM;
963 sb->s_root = d_make_root(root_inode);
964 if (sb->s_root == NULL)
965 goto out;
966
967 return 0;
968
969 out_put:
970 iput(root_inode);
971 out:
972 return err;
973 }
974
975 static struct dentry *hostfs_read_sb(struct file_system_type *type,
976 int flags, const char *dev_name,
977 void *data)
978 {
979 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
980 }
981
982 static void hostfs_kill_sb(struct super_block *s)
983 {
984 kill_anon_super(s);
985 kfree(s->s_fs_info);
986 }
987
988 static struct file_system_type hostfs_type = {
989 .owner = THIS_MODULE,
990 .name = "hostfs",
991 .mount = hostfs_read_sb,
992 .kill_sb = hostfs_kill_sb,
993 .fs_flags = 0,
994 };
995 MODULE_ALIAS_FS("hostfs");
996
997 static int __init init_hostfs(void)
998 {
999 return register_filesystem(&hostfs_type);
1000 }
1001
1002 static void __exit exit_hostfs(void)
1003 {
1004 unregister_filesystem(&hostfs_type);
1005 }
1006
1007 module_init(init_hostfs)
1008 module_exit(exit_hostfs)
1009 MODULE_LICENSE("GPL");
Linux with added FPC-III support