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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
22struct hostfs_inode_info {
23 int fd;
24 fmode_t mode;
25 struct inode vfs_inode;
26};
27
28static 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
35static int hostfs_d_delete(const struct dentry *dentry)
36{
37 return 1;
38}
39
40static const struct dentry_operations hostfs_dentry_ops = {
41 .d_delete = hostfs_d_delete,
42};
43
44
45static char *root_ino = "";
46static int append = 0;
47
48#define HOSTFS_SUPER_MAGIC 0x00c0ffee
49
50static const struct inode_operations hostfs_iops;
51static const struct inode_operations hostfs_dir_iops;
52static const struct inode_operations hostfs_link_iops;
53
54#ifndef MODULE
55static 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
93static 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
118static char *dentry_name(struct dentry *dentry)
119{
120 char *name = __getname();
121 if (!name)
122 return NULL;
123
124 return __dentry_name(dentry, name);
125}
126
127static 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
143static 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
191static 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
199int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
200{
201
202
203
204
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
228static 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
240static 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
250static 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
257static void hostfs_destroy_inode(struct inode *inode)
258{
259 call_rcu(&inode->i_rcu, hostfs_i_callback);
260}
261
262static 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
273static 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
281int 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
306int 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
320retry:
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
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
365int 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
381static 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
394static const struct file_operations hostfs_dir_fops = {
395 .llseek = generic_file_llseek,
396 .readdir = hostfs_readdir,
397 .read = generic_read_dir,
398};
399
400int 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
436int 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
461int 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
473int 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
491
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
501static 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
509static 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
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
555int 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
597struct 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
634int 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
652int 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
668int 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
680int 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
692int 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
704int 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
744int 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
762int 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
788int 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
861static 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
874static 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
888static 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
912static 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
919static 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
925static 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
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
976out_put:
977 iput(root_inode);
978out:
979 return err;
980}
981
982static 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
989static void hostfs_kill_sb(struct super_block *s)
990{
991 kill_anon_super(s);
992 kfree(s->s_fs_info);
993}
994
995static 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
1003static int __init init_hostfs(void)
1004{
1005 return register_filesystem(&hostfs_type);
1006}
1007
1008static void __exit exit_hostfs(void)
1009{
1010 unregister_filesystem(&hostfs_type);
1011}
1012
1013module_init(init_hostfs)
1014module_exit(exit_hostfs)
1015MODULE_LICENSE("GPL");
1016
