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Merge branch 'v6v7' into devel
[linux/fpc-iii.git] / fs / hostfs / hostfs_kern.c
blob2638c834ed281db783f6a7cd5ef24e2edb2047e4
1 /*
2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 *
5 * Ported the filesystem routines to 2.5.
6 * 2003-02-10 Petr Baudis <pasky@ucw.cz>
7 */
8
9 #include <linux/fs.h>
10 #include <linux/module.h>
11 #include <linux/mm.h>
12 #include <linux/pagemap.h>
13 #include <linux/statfs.h>
14 #include <linux/slab.h>
15 #include <linux/seq_file.h>
16 #include <linux/mount.h>
17 #include <linux/namei.h>
18 #include "hostfs.h"
19 #include "init.h"
20 #include "kern.h"
21
22 struct hostfs_inode_info {
23 int fd;
24 fmode_t mode;
25 struct inode vfs_inode;
26 };
27
28 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
29 {
30 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
31 }
32
33 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode)
34
35 static int hostfs_d_delete(const struct dentry *dentry)
36 {
37 return 1;
38 }
39
40 static const struct dentry_operations hostfs_dentry_ops = {
41 .d_delete = hostfs_d_delete,
42 };
43
44 /* Changed in hostfs_args before the kernel starts running */
45 static char *root_ino = "";
46 static int append = 0;
47
48 #define HOSTFS_SUPER_MAGIC 0x00c0ffee
49
50 static const struct inode_operations hostfs_iops;
51 static const struct inode_operations hostfs_dir_iops;
52 static const struct inode_operations hostfs_link_iops;
53
54 #ifndef MODULE
55 static int __init hostfs_args(char *options, int *add)
56 {
57 char *ptr;
58
59 ptr = strchr(options, ',');
60 if (ptr != NULL)
61 *ptr++ = '\0';
62 if (*options != '\0')
63 root_ino = options;
64
65 options = ptr;
66 while (options) {
67 ptr = strchr(options, ',');
68 if (ptr != NULL)
69 *ptr++ = '\0';
70 if (*options != '\0') {
71 if (!strcmp(options, "append"))
72 append = 1;
73 else printf("hostfs_args - unsupported option - %s\n",
74 options);
75 }
76 options = ptr;
77 }
78 return 0;
79 }
80
81 __uml_setup("hostfs=", hostfs_args,
82 "hostfs=<root dir>,<flags>,...\n"
83 " This is used to set hostfs parameters. The root directory argument\n"
84 " is used to confine all hostfs mounts to within the specified directory\n"
85 " tree on the host. If this isn't specified, then a user inside UML can\n"
86 " mount anything on the host that's accessible to the user that's running\n"
87 " it.\n"
88 " The only flag currently supported is 'append', which specifies that all\n"
89 " files opened by hostfs will be opened in append mode.\n\n"
90 );
91 #endif
92
93 static char *__dentry_name(struct dentry *dentry, char *name)
94 {
95 char *p = dentry_path_raw(dentry, name, PATH_MAX);
96 char *root;
97 size_t len;
98
99 root = dentry->d_sb->s_fs_info;
100 len = strlen(root);
101 if (IS_ERR(p)) {
102 __putname(name);
103 return NULL;
104 }
105 strlcpy(name, root, PATH_MAX);
106 if (len > p - name) {
107 __putname(name);
108 return NULL;
109 }
110 if (p > name + len) {
111 char *s = name + len;
112 while ((*s++ = *p++) != '\0')
113 ;
114 }
115 return name;
116 }
117
118 static char *dentry_name(struct dentry *dentry)
119 {
120 char *name = __getname();
121 if (!name)
122 return NULL;
123
124 return __dentry_name(dentry, name); /* will unlock */
125 }
126
127 static char *inode_name(struct inode *ino)
128 {
129 struct dentry *dentry;
130 char *name;
131
132 dentry = d_find_alias(ino);
133 if (!dentry)
134 return NULL;
135
136 name = dentry_name(dentry);
137
138 dput(dentry);
139
140 return name;
141 }
142
143 static char *follow_link(char *link)
144 {
145 int len, n;
146 char *name, *resolved, *end;
147
148 len = 64;
149 while (1) {
150 n = -ENOMEM;
151 name = kmalloc(len, GFP_KERNEL);
152 if (name == NULL)
153 goto out;
154
155 n = hostfs_do_readlink(link, name, len);
156 if (n < len)
157 break;
158 len *= 2;
159 kfree(name);
160 }
161 if (n < 0)
162 goto out_free;
163
164 if (*name == '/')
165 return name;
166
167 end = strrchr(link, '/');
168 if (end == NULL)
169 return name;
170
171 *(end + 1) = '\0';
172 len = strlen(link) + strlen(name) + 1;
173
174 resolved = kmalloc(len, GFP_KERNEL);
175 if (resolved == NULL) {
176 n = -ENOMEM;
177 goto out_free;
178 }
179
180 sprintf(resolved, "%s%s", link, name);
181 kfree(name);
182 kfree(link);
183 return resolved;
184
185 out_free:
186 kfree(name);
187 out:
188 return ERR_PTR(n);
189 }
190
191 static struct inode *hostfs_iget(struct super_block *sb)
192 {
193 struct inode *inode = new_inode(sb);
194 if (!inode)
195 return ERR_PTR(-ENOMEM);
196 return inode;
197 }
198
199 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
200 {
201 /*
202 * do_statfs uses struct statfs64 internally, but the linux kernel
203 * struct statfs still has 32-bit versions for most of these fields,
204 * so we convert them here
205 */
206 int err;
207 long long f_blocks;
208 long long f_bfree;
209 long long f_bavail;
210 long long f_files;
211 long long f_ffree;
212
213 err = do_statfs(dentry->d_sb->s_fs_info,
214 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
215 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
216 &sf->f_namelen);
217 if (err)
218 return err;
219 sf->f_blocks = f_blocks;
220 sf->f_bfree = f_bfree;
221 sf->f_bavail = f_bavail;
222 sf->f_files = f_files;
223 sf->f_ffree = f_ffree;
224 sf->f_type = HOSTFS_SUPER_MAGIC;
225 return 0;
226 }
227
228 static struct inode *hostfs_alloc_inode(struct super_block *sb)
229 {
230 struct hostfs_inode_info *hi;
231
232 hi = kzalloc(sizeof(*hi), GFP_KERNEL);
233 if (hi == NULL)
234 return NULL;
235 hi->fd = -1;
236 inode_init_once(&hi->vfs_inode);
237 return &hi->vfs_inode;
238 }
239
240 static void hostfs_evict_inode(struct inode *inode)
241 {
242 truncate_inode_pages(&inode->i_data, 0);
243 end_writeback(inode);
244 if (HOSTFS_I(inode)->fd != -1) {
245 close_file(&HOSTFS_I(inode)->fd);
246 HOSTFS_I(inode)->fd = -1;
247 }
248 }
249
250 static void hostfs_i_callback(struct rcu_head *head)
251 {
252 struct inode *inode = container_of(head, struct inode, i_rcu);
253 INIT_LIST_HEAD(&inode->i_dentry);
254 kfree(HOSTFS_I(inode));
255 }
256
257 static void hostfs_destroy_inode(struct inode *inode)
258 {
259 call_rcu(&inode->i_rcu, hostfs_i_callback);
260 }
261
262 static int hostfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
263 {
264 const char *root_path = vfs->mnt_sb->s_fs_info;
265 size_t offset = strlen(root_ino) + 1;
266
267 if (strlen(root_path) > offset)
268 seq_printf(seq, ",%s", root_path + offset);
269
270 return 0;
271 }
272
273 static const struct super_operations hostfs_sbops = {
274 .alloc_inode = hostfs_alloc_inode,
275 .destroy_inode = hostfs_destroy_inode,
276 .evict_inode = hostfs_evict_inode,
277 .statfs = hostfs_statfs,
278 .show_options = hostfs_show_options,
279 };
280
281 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
282 {
283 void *dir;
284 char *name;
285 unsigned long long next, ino;
286 int error, len;
287
288 name = dentry_name(file->f_path.dentry);
289 if (name == NULL)
290 return -ENOMEM;
291 dir = open_dir(name, &error);
292 __putname(name);
293 if (dir == NULL)
294 return -error;
295 next = file->f_pos;
296 while ((name = read_dir(dir, &next, &ino, &len)) != NULL) {
297 error = (*filldir)(ent, name, len, file->f_pos,
298 ino, DT_UNKNOWN);
299 if (error) break;
300 file->f_pos = next;
301 }
302 close_dir(dir);
303 return 0;
304 }
305
306 int hostfs_file_open(struct inode *ino, struct file *file)
307 {
308 static DEFINE_MUTEX(open_mutex);
309 char *name;
310 fmode_t mode = 0;
311 int err;
312 int r = 0, w = 0, fd;
313
314 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
315 if ((mode & HOSTFS_I(ino)->mode) == mode)
316 return 0;
317
318 mode |= HOSTFS_I(ino)->mode;
319
320 retry:
321 if (mode & FMODE_READ)
322 r = 1;
323 if (mode & FMODE_WRITE)
324 w = 1;
325 if (w)
326 r = 1;
327
328 name = dentry_name(file->f_path.dentry);
329 if (name == NULL)
330 return -ENOMEM;
331
332 fd = open_file(name, r, w, append);
333 __putname(name);
334 if (fd < 0)
335 return fd;
336
337 mutex_lock(&open_mutex);
338 /* somebody else had handled it first? */
339 if ((mode & HOSTFS_I(ino)->mode) == mode) {
340 mutex_unlock(&open_mutex);
341 return 0;
342 }
343 if ((mode | HOSTFS_I(ino)->mode) != mode) {
344 mode |= HOSTFS_I(ino)->mode;
345 mutex_unlock(&open_mutex);
346 close_file(&fd);
347 goto retry;
348 }
349 if (HOSTFS_I(ino)->fd == -1) {
350 HOSTFS_I(ino)->fd = fd;
351 } else {
352 err = replace_file(fd, HOSTFS_I(ino)->fd);
353 close_file(&fd);
354 if (err < 0) {
355 mutex_unlock(&open_mutex);
356 return err;
357 }
358 }
359 HOSTFS_I(ino)->mode = mode;
360 mutex_unlock(&open_mutex);
361
362 return 0;
363 }
364
365 int hostfs_fsync(struct file *file, int datasync)
366 {
367 return fsync_file(HOSTFS_I(file->f_mapping->host)->fd, datasync);
368 }
369
370 static const struct file_operations hostfs_file_fops = {
371 .llseek = generic_file_llseek,
372 .read = do_sync_read,
373 .splice_read = generic_file_splice_read,
374 .aio_read = generic_file_aio_read,
375 .aio_write = generic_file_aio_write,
376 .write = do_sync_write,
377 .mmap = generic_file_mmap,
378 .open = hostfs_file_open,
379 .release = NULL,
380 .fsync = hostfs_fsync,
381 };
382
383 static const struct file_operations hostfs_dir_fops = {
384 .llseek = generic_file_llseek,
385 .readdir = hostfs_readdir,
386 .read = generic_read_dir,
387 };
388
389 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
390 {
391 struct address_space *mapping = page->mapping;
392 struct inode *inode = mapping->host;
393 char *buffer;
394 unsigned long long base;
395 int count = PAGE_CACHE_SIZE;
396 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
397 int err;
398
399 if (page->index >= end_index)
400 count = inode->i_size & (PAGE_CACHE_SIZE-1);
401
402 buffer = kmap(page);
403 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
404
405 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
406 if (err != count) {
407 ClearPageUptodate(page);
408 goto out;
409 }
410
411 if (base > inode->i_size)
412 inode->i_size = base;
413
414 if (PageError(page))
415 ClearPageError(page);
416 err = 0;
417
418 out:
419 kunmap(page);
420
421 unlock_page(page);
422 return err;
423 }
424
425 int hostfs_readpage(struct file *file, struct page *page)
426 {
427 char *buffer;
428 long long start;
429 int err = 0;
430
431 start = (long long) page->index << PAGE_CACHE_SHIFT;
432 buffer = kmap(page);
433 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
434 PAGE_CACHE_SIZE);
435 if (err < 0)
436 goto out;
437
438 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
439
440 flush_dcache_page(page);
441 SetPageUptodate(page);
442 if (PageError(page)) ClearPageError(page);
443 err = 0;
444 out:
445 kunmap(page);
446 unlock_page(page);
447 return err;
448 }
449
450 int hostfs_write_begin(struct file *file, struct address_space *mapping,
451 loff_t pos, unsigned len, unsigned flags,
452 struct page **pagep, void **fsdata)
453 {
454 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
455
456 *pagep = grab_cache_page_write_begin(mapping, index, flags);
457 if (!*pagep)
458 return -ENOMEM;
459 return 0;
460 }
461
462 int hostfs_write_end(struct file *file, struct address_space *mapping,
463 loff_t pos, unsigned len, unsigned copied,
464 struct page *page, void *fsdata)
465 {
466 struct inode *inode = mapping->host;
467 void *buffer;
468 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
469 int err;
470
471 buffer = kmap(page);
472 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
473 kunmap(page);
474
475 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
476 SetPageUptodate(page);
477
478 /*
479 * If err > 0, write_file has added err to pos, so we are comparing
480 * i_size against the last byte written.
481 */
482 if (err > 0 && (pos > inode->i_size))
483 inode->i_size = pos;
484 unlock_page(page);
485 page_cache_release(page);
486
487 return err;
488 }
489
490 static const struct address_space_operations hostfs_aops = {
491 .writepage = hostfs_writepage,
492 .readpage = hostfs_readpage,
493 .set_page_dirty = __set_page_dirty_nobuffers,
494 .write_begin = hostfs_write_begin,
495 .write_end = hostfs_write_end,
496 };
497
498 static int read_name(struct inode *ino, char *name)
499 {
500 dev_t rdev;
501 struct hostfs_stat st;
502 int err = stat_file(name, &st, -1);
503 if (err)
504 return err;
505
506 /* Reencode maj and min with the kernel encoding.*/
507 rdev = MKDEV(st.maj, st.min);
508
509 switch (st.mode & S_IFMT) {
510 case S_IFLNK:
511 ino->i_op = &hostfs_link_iops;
512 break;
513 case S_IFDIR:
514 ino->i_op = &hostfs_dir_iops;
515 ino->i_fop = &hostfs_dir_fops;
516 break;
517 case S_IFCHR:
518 case S_IFBLK:
519 case S_IFIFO:
520 case S_IFSOCK:
521 init_special_inode(ino, st.mode & S_IFMT, rdev);
522 ino->i_op = &hostfs_iops;
523 break;
524
525 default:
526 ino->i_op = &hostfs_iops;
527 ino->i_fop = &hostfs_file_fops;
528 ino->i_mapping->a_ops = &hostfs_aops;
529 }
530
531 ino->i_ino = st.ino;
532 ino->i_mode = st.mode;
533 ino->i_nlink = st.nlink;
534 ino->i_uid = st.uid;
535 ino->i_gid = st.gid;
536 ino->i_atime = st.atime;
537 ino->i_mtime = st.mtime;
538 ino->i_ctime = st.ctime;
539 ino->i_size = st.size;
540 ino->i_blocks = st.blocks;
541 return 0;
542 }
543
544 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
545 struct nameidata *nd)
546 {
547 struct inode *inode;
548 char *name;
549 int error, fd;
550
551 inode = hostfs_iget(dir->i_sb);
552 if (IS_ERR(inode)) {
553 error = PTR_ERR(inode);
554 goto out;
555 }
556
557 error = -ENOMEM;
558 name = dentry_name(dentry);
559 if (name == NULL)
560 goto out_put;
561
562 fd = file_create(name,
563 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
564 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
565 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
566 if (fd < 0)
567 error = fd;
568 else
569 error = read_name(inode, name);
570
571 __putname(name);
572 if (error)
573 goto out_put;
574
575 HOSTFS_I(inode)->fd = fd;
576 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
577 d_instantiate(dentry, inode);
578 return 0;
579
580 out_put:
581 iput(inode);
582 out:
583 return error;
584 }
585
586 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
587 struct nameidata *nd)
588 {
589 struct inode *inode;
590 char *name;
591 int err;
592
593 inode = hostfs_iget(ino->i_sb);
594 if (IS_ERR(inode)) {
595 err = PTR_ERR(inode);
596 goto out;
597 }
598
599 err = -ENOMEM;
600 name = dentry_name(dentry);
601 if (name == NULL)
602 goto out_put;
603
604 err = read_name(inode, name);
605
606 __putname(name);
607 if (err == -ENOENT) {
608 iput(inode);
609 inode = NULL;
610 }
611 else if (err)
612 goto out_put;
613
614 d_add(dentry, inode);
615 return NULL;
616
617 out_put:
618 iput(inode);
619 out:
620 return ERR_PTR(err);
621 }
622
623 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
624 {
625 char *from_name, *to_name;
626 int err;
627
628 if ((from_name = dentry_name(from)) == NULL)
629 return -ENOMEM;
630 to_name = dentry_name(to);
631 if (to_name == NULL) {
632 __putname(from_name);
633 return -ENOMEM;
634 }
635 err = link_file(to_name, from_name);
636 __putname(from_name);
637 __putname(to_name);
638 return err;
639 }
640
641 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
642 {
643 char *file;
644 int err;
645
646 if (append)
647 return -EPERM;
648
649 if ((file = dentry_name(dentry)) == NULL)
650 return -ENOMEM;
651
652 err = unlink_file(file);
653 __putname(file);
654 return err;
655 }
656
657 int hostfs_symlink(struct inode *ino, struct dentry *dentry, 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 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int 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 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 = do_rmdir(file);
689 __putname(file);
690 return err;
691 }
692
693 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int 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 if (err)
720 goto out_put;
721
722 d_instantiate(dentry, inode);
723 return 0;
724
725 out_free:
726 __putname(name);
727 out_put:
728 iput(inode);
729 out:
730 return err;
731 }
732
733 int hostfs_rename(struct inode *from_ino, struct dentry *from,
734 struct inode *to_ino, struct dentry *to)
735 {
736 char *from_name, *to_name;
737 int err;
738
739 if ((from_name = dentry_name(from)) == NULL)
740 return -ENOMEM;
741 if ((to_name = dentry_name(to)) == NULL) {
742 __putname(from_name);
743 return -ENOMEM;
744 }
745 err = rename_file(from_name, to_name);
746 __putname(from_name);
747 __putname(to_name);
748 return err;
749 }
750
751 int hostfs_permission(struct inode *ino, int desired, unsigned int flags)
752 {
753 char *name;
754 int r = 0, w = 0, x = 0, err;
755
756 if (flags & IPERM_FLAG_RCU)
757 return -ECHILD;
758
759 if (desired & MAY_READ) r = 1;
760 if (desired & MAY_WRITE) w = 1;
761 if (desired & MAY_EXEC) x = 1;
762 name = inode_name(ino);
763 if (name == NULL)
764 return -ENOMEM;
765
766 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
767 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
768 err = 0;
769 else
770 err = access_file(name, r, w, x);
771 __putname(name);
772 if (!err)
773 err = generic_permission(ino, desired, flags, NULL);
774 return err;
775 }
776
777 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
778 {
779 struct inode *inode = dentry->d_inode;
780 struct hostfs_iattr attrs;
781 char *name;
782 int err;
783
784 int fd = HOSTFS_I(inode)->fd;
785
786 err = inode_change_ok(inode, attr);
787 if (err)
788 return err;
789
790 if (append)
791 attr->ia_valid &= ~ATTR_SIZE;
792
793 attrs.ia_valid = 0;
794 if (attr->ia_valid & ATTR_MODE) {
795 attrs.ia_valid |= HOSTFS_ATTR_MODE;
796 attrs.ia_mode = attr->ia_mode;
797 }
798 if (attr->ia_valid & ATTR_UID) {
799 attrs.ia_valid |= HOSTFS_ATTR_UID;
800 attrs.ia_uid = attr->ia_uid;
801 }
802 if (attr->ia_valid & ATTR_GID) {
803 attrs.ia_valid |= HOSTFS_ATTR_GID;
804 attrs.ia_gid = attr->ia_gid;
805 }
806 if (attr->ia_valid & ATTR_SIZE) {
807 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
808 attrs.ia_size = attr->ia_size;
809 }
810 if (attr->ia_valid & ATTR_ATIME) {
811 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
812 attrs.ia_atime = attr->ia_atime;
813 }
814 if (attr->ia_valid & ATTR_MTIME) {
815 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
816 attrs.ia_mtime = attr->ia_mtime;
817 }
818 if (attr->ia_valid & ATTR_CTIME) {
819 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
820 attrs.ia_ctime = attr->ia_ctime;
821 }
822 if (attr->ia_valid & ATTR_ATIME_SET) {
823 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
824 }
825 if (attr->ia_valid & ATTR_MTIME_SET) {
826 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
827 }
828 name = dentry_name(dentry);
829 if (name == NULL)
830 return -ENOMEM;
831 err = set_attr(name, &attrs, fd);
832 __putname(name);
833 if (err)
834 return err;
835
836 if ((attr->ia_valid & ATTR_SIZE) &&
837 attr->ia_size != i_size_read(inode)) {
838 int error;
839
840 error = vmtruncate(inode, attr->ia_size);
841 if (err)
842 return err;
843 }
844
845 setattr_copy(inode, attr);
846 mark_inode_dirty(inode);
847 return 0;
848 }
849
850 static const struct inode_operations hostfs_iops = {
851 .create = hostfs_create,
852 .link = hostfs_link,
853 .unlink = hostfs_unlink,
854 .symlink = hostfs_symlink,
855 .mkdir = hostfs_mkdir,
856 .rmdir = hostfs_rmdir,
857 .mknod = hostfs_mknod,
858 .rename = hostfs_rename,
859 .permission = hostfs_permission,
860 .setattr = hostfs_setattr,
861 };
862
863 static const struct inode_operations hostfs_dir_iops = {
864 .create = hostfs_create,
865 .lookup = hostfs_lookup,
866 .link = hostfs_link,
867 .unlink = hostfs_unlink,
868 .symlink = hostfs_symlink,
869 .mkdir = hostfs_mkdir,
870 .rmdir = hostfs_rmdir,
871 .mknod = hostfs_mknod,
872 .rename = hostfs_rename,
873 .permission = hostfs_permission,
874 .setattr = hostfs_setattr,
875 };
876
877 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
878 {
879 char *link = __getname();
880 if (link) {
881 char *path = dentry_name(dentry);
882 int err = -ENOMEM;
883 if (path) {
884 err = hostfs_do_readlink(path, link, PATH_MAX);
885 if (err == PATH_MAX)
886 err = -E2BIG;
887 __putname(path);
888 }
889 if (err < 0) {
890 __putname(link);
891 link = ERR_PTR(err);
892 }
893 } else {
894 link = ERR_PTR(-ENOMEM);
895 }
896
897 nd_set_link(nd, link);
898 return NULL;
899 }
900
901 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
902 {
903 char *s = nd_get_link(nd);
904 if (!IS_ERR(s))
905 __putname(s);
906 }
907
908 static const struct inode_operations hostfs_link_iops = {
909 .readlink = generic_readlink,
910 .follow_link = hostfs_follow_link,
911 .put_link = hostfs_put_link,
912 };
913
914 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
915 {
916 struct inode *root_inode;
917 char *host_root_path, *req_root = d;
918 int err;
919
920 sb->s_blocksize = 1024;
921 sb->s_blocksize_bits = 10;
922 sb->s_magic = HOSTFS_SUPER_MAGIC;
923 sb->s_op = &hostfs_sbops;
924 sb->s_d_op = &hostfs_dentry_ops;
925 sb->s_maxbytes = MAX_LFS_FILESIZE;
926
927 /* NULL is printed as <NULL> by sprintf: avoid that. */
928 if (req_root == NULL)
929 req_root = "";
930
931 err = -ENOMEM;
932 sb->s_fs_info = host_root_path =
933 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
934 if (host_root_path == NULL)
935 goto out;
936
937 sprintf(host_root_path, "%s/%s", root_ino, req_root);
938
939 root_inode = new_inode(sb);
940 if (!root_inode)
941 goto out;
942
943 err = read_name(root_inode, host_root_path);
944 if (err)
945 goto out_put;
946
947 if (S_ISLNK(root_inode->i_mode)) {
948 char *name = follow_link(host_root_path);
949 if (IS_ERR(name))
950 err = PTR_ERR(name);
951 else
952 err = read_name(root_inode, name);
953 kfree(name);
954 if (err)
955 goto out_put;
956 }
957
958 err = -ENOMEM;
959 sb->s_root = d_alloc_root(root_inode);
960 if (sb->s_root == NULL)
961 goto out_put;
962
963 return 0;
964
965 out_put:
966 iput(root_inode);
967 out:
968 return err;
969 }
970
971 static struct dentry *hostfs_read_sb(struct file_system_type *type,
972 int flags, const char *dev_name,
973 void *data)
974 {
975 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
976 }
977
978 static void hostfs_kill_sb(struct super_block *s)
979 {
980 kill_anon_super(s);
981 kfree(s->s_fs_info);
982 }
983
984 static struct file_system_type hostfs_type = {
985 .owner = THIS_MODULE,
986 .name = "hostfs",
987 .mount = hostfs_read_sb,
988 .kill_sb = hostfs_kill_sb,
989 .fs_flags = 0,
990 };
991
992 static int __init init_hostfs(void)
993 {
994 return register_filesystem(&hostfs_type);
995 }
996
997 static void __exit exit_hostfs(void)
998 {
999 unregister_filesystem(&hostfs_type);
1000 }
1001
1002 module_init(init_hostfs)
1003 module_exit(exit_hostfs)
1004 MODULE_LICENSE("GPL");
Linux with added FPC-III support