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fs/Makefile: Stupid typo breakage of exofs inclusion
[linux-btrfs-devel.git] / fs / hostfs / hostfs_kern.c
blob0d22afdd4611d53383957b86bc8688cba62ef3d4
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, loff_t start, loff_t end, int datasync)
366 {
367 struct inode *inode = file->f_mapping->host;
368 int ret;
369
370 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
371 if (ret)
372 return ret;
373
374 mutex_lock(&inode->i_mutex);
375 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
376 mutex_unlock(&inode->i_mutex);
377
378 return ret;
379 }
380
381 static const struct file_operations hostfs_file_fops = {
382 .llseek = generic_file_llseek,
383 .read = do_sync_read,
384 .splice_read = generic_file_splice_read,
385 .aio_read = generic_file_aio_read,
386 .aio_write = generic_file_aio_write,
387 .write = do_sync_write,
388 .mmap = generic_file_mmap,
389 .open = hostfs_file_open,
390 .release = NULL,
391 .fsync = hostfs_fsync,
392 };
393
394 static const struct file_operations hostfs_dir_fops = {
395 .llseek = generic_file_llseek,
396 .readdir = hostfs_readdir,
397 .read = generic_read_dir,
398 };
399
400 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
401 {
402 struct address_space *mapping = page->mapping;
403 struct inode *inode = mapping->host;
404 char *buffer;
405 unsigned long long base;
406 int count = PAGE_CACHE_SIZE;
407 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
408 int err;
409
410 if (page->index >= end_index)
411 count = inode->i_size & (PAGE_CACHE_SIZE-1);
412
413 buffer = kmap(page);
414 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
415
416 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
417 if (err != count) {
418 ClearPageUptodate(page);
419 goto out;
420 }
421
422 if (base > inode->i_size)
423 inode->i_size = base;
424
425 if (PageError(page))
426 ClearPageError(page);
427 err = 0;
428
429 out:
430 kunmap(page);
431
432 unlock_page(page);
433 return err;
434 }
435
436 int hostfs_readpage(struct file *file, struct page *page)
437 {
438 char *buffer;
439 long long start;
440 int err = 0;
441
442 start = (long long) page->index << PAGE_CACHE_SHIFT;
443 buffer = kmap(page);
444 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
445 PAGE_CACHE_SIZE);
446 if (err < 0)
447 goto out;
448
449 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
450
451 flush_dcache_page(page);
452 SetPageUptodate(page);
453 if (PageError(page)) ClearPageError(page);
454 err = 0;
455 out:
456 kunmap(page);
457 unlock_page(page);
458 return err;
459 }
460
461 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_CACHE_SHIFT;
466
467 *pagep = grab_cache_page_write_begin(mapping, index, flags);
468 if (!*pagep)
469 return -ENOMEM;
470 return 0;
471 }
472
473 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_CACHE_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_CACHE_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 page_cache_release(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
536 default:
537 ino->i_op = &hostfs_iops;
538 ino->i_fop = &hostfs_file_fops;
539 ino->i_mapping->a_ops = &hostfs_aops;
540 }
541
542 ino->i_ino = st.ino;
543 ino->i_mode = st.mode;
544 ino->i_nlink = st.nlink;
545 ino->i_uid = st.uid;
546 ino->i_gid = st.gid;
547 ino->i_atime = st.atime;
548 ino->i_mtime = st.mtime;
549 ino->i_ctime = st.ctime;
550 ino->i_size = st.size;
551 ino->i_blocks = st.blocks;
552 return 0;
553 }
554
555 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
556 struct nameidata *nd)
557 {
558 struct inode *inode;
559 char *name;
560 int error, fd;
561
562 inode = hostfs_iget(dir->i_sb);
563 if (IS_ERR(inode)) {
564 error = PTR_ERR(inode);
565 goto out;
566 }
567
568 error = -ENOMEM;
569 name = dentry_name(dentry);
570 if (name == NULL)
571 goto out_put;
572
573 fd = file_create(name,
574 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
575 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
576 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
577 if (fd < 0)
578 error = fd;
579 else
580 error = read_name(inode, name);
581
582 __putname(name);
583 if (error)
584 goto out_put;
585
586 HOSTFS_I(inode)->fd = fd;
587 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
588 d_instantiate(dentry, inode);
589 return 0;
590
591 out_put:
592 iput(inode);
593 out:
594 return error;
595 }
596
597 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
598 struct nameidata *nd)
599 {
600 struct inode *inode;
601 char *name;
602 int err;
603
604 inode = hostfs_iget(ino->i_sb);
605 if (IS_ERR(inode)) {
606 err = PTR_ERR(inode);
607 goto out;
608 }
609
610 err = -ENOMEM;
611 name = dentry_name(dentry);
612 if (name == NULL)
613 goto out_put;
614
615 err = read_name(inode, name);
616
617 __putname(name);
618 if (err == -ENOENT) {
619 iput(inode);
620 inode = NULL;
621 }
622 else if (err)
623 goto out_put;
624
625 d_add(dentry, inode);
626 return NULL;
627
628 out_put:
629 iput(inode);
630 out:
631 return ERR_PTR(err);
632 }
633
634 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
635 {
636 char *from_name, *to_name;
637 int err;
638
639 if ((from_name = dentry_name(from)) == NULL)
640 return -ENOMEM;
641 to_name = dentry_name(to);
642 if (to_name == NULL) {
643 __putname(from_name);
644 return -ENOMEM;
645 }
646 err = link_file(to_name, from_name);
647 __putname(from_name);
648 __putname(to_name);
649 return err;
650 }
651
652 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
653 {
654 char *file;
655 int err;
656
657 if (append)
658 return -EPERM;
659
660 if ((file = dentry_name(dentry)) == NULL)
661 return -ENOMEM;
662
663 err = unlink_file(file);
664 __putname(file);
665 return err;
666 }
667
668 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
669 {
670 char *file;
671 int err;
672
673 if ((file = dentry_name(dentry)) == NULL)
674 return -ENOMEM;
675 err = make_symlink(file, to);
676 __putname(file);
677 return err;
678 }
679
680 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
681 {
682 char *file;
683 int err;
684
685 if ((file = dentry_name(dentry)) == NULL)
686 return -ENOMEM;
687 err = do_mkdir(file, mode);
688 __putname(file);
689 return err;
690 }
691
692 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
693 {
694 char *file;
695 int err;
696
697 if ((file = dentry_name(dentry)) == NULL)
698 return -ENOMEM;
699 err = do_rmdir(file);
700 __putname(file);
701 return err;
702 }
703
704 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
705 {
706 struct inode *inode;
707 char *name;
708 int err;
709
710 inode = hostfs_iget(dir->i_sb);
711 if (IS_ERR(inode)) {
712 err = PTR_ERR(inode);
713 goto out;
714 }
715
716 err = -ENOMEM;
717 name = dentry_name(dentry);
718 if (name == NULL)
719 goto out_put;
720
721 init_special_inode(inode, mode, dev);
722 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
723 if (!err)
724 goto out_free;
725
726 err = read_name(inode, name);
727 __putname(name);
728 if (err)
729 goto out_put;
730 if (err)
731 goto out_put;
732
733 d_instantiate(dentry, inode);
734 return 0;
735
736 out_free:
737 __putname(name);
738 out_put:
739 iput(inode);
740 out:
741 return err;
742 }
743
744 int hostfs_rename(struct inode *from_ino, struct dentry *from,
745 struct inode *to_ino, struct dentry *to)
746 {
747 char *from_name, *to_name;
748 int err;
749
750 if ((from_name = dentry_name(from)) == NULL)
751 return -ENOMEM;
752 if ((to_name = dentry_name(to)) == NULL) {
753 __putname(from_name);
754 return -ENOMEM;
755 }
756 err = rename_file(from_name, to_name);
757 __putname(from_name);
758 __putname(to_name);
759 return err;
760 }
761
762 int hostfs_permission(struct inode *ino, int desired)
763 {
764 char *name;
765 int r = 0, w = 0, x = 0, err;
766
767 if (desired & MAY_NOT_BLOCK)
768 return -ECHILD;
769
770 if (desired & MAY_READ) r = 1;
771 if (desired & MAY_WRITE) w = 1;
772 if (desired & MAY_EXEC) x = 1;
773 name = inode_name(ino);
774 if (name == NULL)
775 return -ENOMEM;
776
777 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
778 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
779 err = 0;
780 else
781 err = access_file(name, r, w, x);
782 __putname(name);
783 if (!err)
784 err = generic_permission(ino, desired);
785 return err;
786 }
787
788 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
789 {
790 struct inode *inode = dentry->d_inode;
791 struct hostfs_iattr attrs;
792 char *name;
793 int err;
794
795 int fd = HOSTFS_I(inode)->fd;
796
797 err = inode_change_ok(inode, attr);
798 if (err)
799 return err;
800
801 if (append)
802 attr->ia_valid &= ~ATTR_SIZE;
803
804 attrs.ia_valid = 0;
805 if (attr->ia_valid & ATTR_MODE) {
806 attrs.ia_valid |= HOSTFS_ATTR_MODE;
807 attrs.ia_mode = attr->ia_mode;
808 }
809 if (attr->ia_valid & ATTR_UID) {
810 attrs.ia_valid |= HOSTFS_ATTR_UID;
811 attrs.ia_uid = attr->ia_uid;
812 }
813 if (attr->ia_valid & ATTR_GID) {
814 attrs.ia_valid |= HOSTFS_ATTR_GID;
815 attrs.ia_gid = attr->ia_gid;
816 }
817 if (attr->ia_valid & ATTR_SIZE) {
818 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
819 attrs.ia_size = attr->ia_size;
820 }
821 if (attr->ia_valid & ATTR_ATIME) {
822 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
823 attrs.ia_atime = attr->ia_atime;
824 }
825 if (attr->ia_valid & ATTR_MTIME) {
826 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
827 attrs.ia_mtime = attr->ia_mtime;
828 }
829 if (attr->ia_valid & ATTR_CTIME) {
830 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
831 attrs.ia_ctime = attr->ia_ctime;
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 int error;
850
851 error = vmtruncate(inode, attr->ia_size);
852 if (err)
853 return err;
854 }
855
856 setattr_copy(inode, attr);
857 mark_inode_dirty(inode);
858 return 0;
859 }
860
861 static const struct inode_operations hostfs_iops = {
862 .create = hostfs_create,
863 .link = hostfs_link,
864 .unlink = hostfs_unlink,
865 .symlink = hostfs_symlink,
866 .mkdir = hostfs_mkdir,
867 .rmdir = hostfs_rmdir,
868 .mknod = hostfs_mknod,
869 .rename = hostfs_rename,
870 .permission = hostfs_permission,
871 .setattr = hostfs_setattr,
872 };
873
874 static const struct inode_operations hostfs_dir_iops = {
875 .create = hostfs_create,
876 .lookup = hostfs_lookup,
877 .link = hostfs_link,
878 .unlink = hostfs_unlink,
879 .symlink = hostfs_symlink,
880 .mkdir = hostfs_mkdir,
881 .rmdir = hostfs_rmdir,
882 .mknod = hostfs_mknod,
883 .rename = hostfs_rename,
884 .permission = hostfs_permission,
885 .setattr = hostfs_setattr,
886 };
887
888 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
889 {
890 char *link = __getname();
891 if (link) {
892 char *path = dentry_name(dentry);
893 int err = -ENOMEM;
894 if (path) {
895 err = hostfs_do_readlink(path, link, PATH_MAX);
896 if (err == PATH_MAX)
897 err = -E2BIG;
898 __putname(path);
899 }
900 if (err < 0) {
901 __putname(link);
902 link = ERR_PTR(err);
903 }
904 } else {
905 link = ERR_PTR(-ENOMEM);
906 }
907
908 nd_set_link(nd, link);
909 return NULL;
910 }
911
912 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
913 {
914 char *s = nd_get_link(nd);
915 if (!IS_ERR(s))
916 __putname(s);
917 }
918
919 static const struct inode_operations hostfs_link_iops = {
920 .readlink = generic_readlink,
921 .follow_link = hostfs_follow_link,
922 .put_link = hostfs_put_link,
923 };
924
925 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
926 {
927 struct inode *root_inode;
928 char *host_root_path, *req_root = d;
929 int err;
930
931 sb->s_blocksize = 1024;
932 sb->s_blocksize_bits = 10;
933 sb->s_magic = HOSTFS_SUPER_MAGIC;
934 sb->s_op = &hostfs_sbops;
935 sb->s_d_op = &hostfs_dentry_ops;
936 sb->s_maxbytes = MAX_LFS_FILESIZE;
937
938 /* NULL is printed as <NULL> by sprintf: avoid that. */
939 if (req_root == NULL)
940 req_root = "";
941
942 err = -ENOMEM;
943 sb->s_fs_info = host_root_path =
944 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
945 if (host_root_path == NULL)
946 goto out;
947
948 sprintf(host_root_path, "%s/%s", root_ino, req_root);
949
950 root_inode = new_inode(sb);
951 if (!root_inode)
952 goto out;
953
954 err = read_name(root_inode, host_root_path);
955 if (err)
956 goto out_put;
957
958 if (S_ISLNK(root_inode->i_mode)) {
959 char *name = follow_link(host_root_path);
960 if (IS_ERR(name))
961 err = PTR_ERR(name);
962 else
963 err = read_name(root_inode, name);
964 kfree(name);
965 if (err)
966 goto out_put;
967 }
968
969 err = -ENOMEM;
970 sb->s_root = d_alloc_root(root_inode);
971 if (sb->s_root == NULL)
972 goto out_put;
973
974 return 0;
975
976 out_put:
977 iput(root_inode);
978 out:
979 return err;
980 }
981
982 static struct dentry *hostfs_read_sb(struct file_system_type *type,
983 int flags, const char *dev_name,
984 void *data)
985 {
986 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
987 }
988
989 static void hostfs_kill_sb(struct super_block *s)
990 {
991 kill_anon_super(s);
992 kfree(s->s_fs_info);
993 }
994
995 static struct file_system_type hostfs_type = {
996 .owner = THIS_MODULE,
997 .name = "hostfs",
998 .mount = hostfs_read_sb,
999 .kill_sb = hostfs_kill_sb,
1000 .fs_flags = 0,
1001 };
1002
1003 static int __init init_hostfs(void)
1004 {
1005 return register_filesystem(&hostfs_type);
1006 }
1007
1008 static void __exit exit_hostfs(void)
1009 {
1010 unregister_filesystem(&hostfs_type);
1011 }
1012
1013 module_init(init_hostfs)
1014 module_exit(exit_hostfs)
1015 MODULE_LICENSE("GPL");
Linux Btrfs Development