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UIO: Documentation
[pv_ops_mirror.git] / fs / hostfs / hostfs_kern.c
blobc77862032e844262a199549d01ca16489b0578f8
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/stddef.h>
10 #include <linux/fs.h>
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/slab.h>
14 #include <linux/pagemap.h>
15 #include <linux/blkdev.h>
16 #include <linux/list.h>
17 #include <linux/statfs.h>
18 #include <linux/kdev_t.h>
19 #include <asm/uaccess.h>
20 #include "hostfs.h"
21 #include "kern_util.h"
22 #include "kern.h"
23 #include "init.h"
24
25 struct hostfs_inode_info {
26 char *host_filename;
27 int fd;
28 int mode;
29 struct inode vfs_inode;
30 };
31
32 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
33 {
34 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
35 }
36
37 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode)
38
39 int hostfs_d_delete(struct dentry *dentry)
40 {
41 return 1;
42 }
43
44 struct dentry_operations hostfs_dentry_ops = {
45 .d_delete = hostfs_d_delete,
46 };
47
48 /* Changed in hostfs_args before the kernel starts running */
49 static char *root_ino = "";
50 static int append = 0;
51
52 #define HOSTFS_SUPER_MAGIC 0x00c0ffee
53
54 static const struct inode_operations hostfs_iops;
55 static const struct inode_operations hostfs_dir_iops;
56 static const struct address_space_operations hostfs_link_aops;
57
58 #ifndef MODULE
59 static int __init hostfs_args(char *options, int *add)
60 {
61 char *ptr;
62
63 ptr = strchr(options, ',');
64 if(ptr != NULL)
65 *ptr++ = '\0';
66 if(*options != '\0')
67 root_ino = options;
68
69 options = ptr;
70 while(options){
71 ptr = strchr(options, ',');
72 if(ptr != NULL)
73 *ptr++ = '\0';
74 if(*options != '\0'){
75 if(!strcmp(options, "append"))
76 append = 1;
77 else printf("hostfs_args - unsupported option - %s\n",
78 options);
79 }
80 options = ptr;
81 }
82 return 0;
83 }
84
85 __uml_setup("hostfs=", hostfs_args,
86 "hostfs=<root dir>,<flags>,...\n"
87 " This is used to set hostfs parameters. The root directory argument\n"
88 " is used to confine all hostfs mounts to within the specified directory\n"
89 " tree on the host. If this isn't specified, then a user inside UML can\n"
90 " mount anything on the host that's accessible to the user that's running\n"
91 " it.\n"
92 " The only flag currently supported is 'append', which specifies that all\n"
93 " files opened by hostfs will be opened in append mode.\n\n"
94 );
95 #endif
96
97 static char *dentry_name(struct dentry *dentry, int extra)
98 {
99 struct dentry *parent;
100 char *root, *name;
101 int len;
102
103 len = 0;
104 parent = dentry;
105 while(parent->d_parent != parent){
106 len += parent->d_name.len + 1;
107 parent = parent->d_parent;
108 }
109
110 root = HOSTFS_I(parent->d_inode)->host_filename;
111 len += strlen(root);
112 name = kmalloc(len + extra + 1, GFP_KERNEL);
113 if(name == NULL)
114 return NULL;
115
116 name[len] = '\0';
117 parent = dentry;
118 while(parent->d_parent != parent){
119 len -= parent->d_name.len + 1;
120 name[len] = '/';
121 strncpy(&name[len + 1], parent->d_name.name,
122 parent->d_name.len);
123 parent = parent->d_parent;
124 }
125 strncpy(name, root, strlen(root));
126 return name;
127 }
128
129 static char *inode_name(struct inode *ino, int extra)
130 {
131 struct dentry *dentry;
132
133 dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias);
134 return dentry_name(dentry, extra);
135 }
136
137 static int read_name(struct inode *ino, char *name)
138 {
139 /* The non-int inode fields are copied into ints by stat_file and
140 * then copied into the inode because passing the actual pointers
141 * in and having them treated as int * breaks on big-endian machines
142 */
143 int err;
144 int i_mode, i_nlink, i_blksize;
145 unsigned long long i_size;
146 unsigned long long i_ino;
147 unsigned long long i_blocks;
148
149 err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
150 &ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
151 &ino->i_ctime, &i_blksize, &i_blocks, -1);
152 if(err)
153 return err;
154
155 ino->i_ino = i_ino;
156 ino->i_mode = i_mode;
157 ino->i_nlink = i_nlink;
158 ino->i_size = i_size;
159 ino->i_blocks = i_blocks;
160 return 0;
161 }
162
163 static char *follow_link(char *link)
164 {
165 int len, n;
166 char *name, *resolved, *end;
167
168 len = 64;
169 while(1){
170 n = -ENOMEM;
171 name = kmalloc(len, GFP_KERNEL);
172 if(name == NULL)
173 goto out;
174
175 n = do_readlink(link, name, len);
176 if(n < len)
177 break;
178 len *= 2;
179 kfree(name);
180 }
181 if(n < 0)
182 goto out_free;
183
184 if(*name == '/')
185 return name;
186
187 end = strrchr(link, '/');
188 if(end == NULL)
189 return name;
190
191 *(end + 1) = '\0';
192 len = strlen(link) + strlen(name) + 1;
193
194 resolved = kmalloc(len, GFP_KERNEL);
195 if(resolved == NULL){
196 n = -ENOMEM;
197 goto out_free;
198 }
199
200 sprintf(resolved, "%s%s", link, name);
201 kfree(name);
202 kfree(link);
203 return resolved;
204
205 out_free:
206 kfree(name);
207 out:
208 return ERR_PTR(n);
209 }
210
211 static int read_inode(struct inode *ino)
212 {
213 char *name;
214 int err = 0;
215
216 /* Unfortunately, we are called from iget() when we don't have a dentry
217 * allocated yet.
218 */
219 if(list_empty(&ino->i_dentry))
220 goto out;
221
222 err = -ENOMEM;
223 name = inode_name(ino, 0);
224 if(name == NULL)
225 goto out;
226
227 if(file_type(name, NULL, NULL) == OS_TYPE_SYMLINK){
228 name = follow_link(name);
229 if(IS_ERR(name)){
230 err = PTR_ERR(name);
231 goto out;
232 }
233 }
234
235 err = read_name(ino, name);
236 kfree(name);
237 out:
238 return err;
239 }
240
241 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
242 {
243 /* do_statfs uses struct statfs64 internally, but the linux kernel
244 * struct statfs still has 32-bit versions for most of these fields,
245 * so we convert them here
246 */
247 int err;
248 long long f_blocks;
249 long long f_bfree;
250 long long f_bavail;
251 long long f_files;
252 long long f_ffree;
253
254 err = do_statfs(HOSTFS_I(dentry->d_sb->s_root->d_inode)->host_filename,
255 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
256 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
257 &sf->f_namelen, sf->f_spare);
258 if(err)
259 return err;
260 sf->f_blocks = f_blocks;
261 sf->f_bfree = f_bfree;
262 sf->f_bavail = f_bavail;
263 sf->f_files = f_files;
264 sf->f_ffree = f_ffree;
265 sf->f_type = HOSTFS_SUPER_MAGIC;
266 return 0;
267 }
268
269 static struct inode *hostfs_alloc_inode(struct super_block *sb)
270 {
271 struct hostfs_inode_info *hi;
272
273 hi = kmalloc(sizeof(*hi), GFP_KERNEL);
274 if(hi == NULL)
275 return NULL;
276
277 *hi = ((struct hostfs_inode_info) { .host_filename = NULL,
278 .fd = -1,
279 .mode = 0 });
280 inode_init_once(&hi->vfs_inode);
281 return &hi->vfs_inode;
282 }
283
284 static void hostfs_delete_inode(struct inode *inode)
285 {
286 truncate_inode_pages(&inode->i_data, 0);
287 if(HOSTFS_I(inode)->fd != -1) {
288 close_file(&HOSTFS_I(inode)->fd);
289 HOSTFS_I(inode)->fd = -1;
290 }
291 clear_inode(inode);
292 }
293
294 static void hostfs_destroy_inode(struct inode *inode)
295 {
296 kfree(HOSTFS_I(inode)->host_filename);
297
298 /*XXX: This should not happen, probably. The check is here for
299 * additional safety.*/
300 if(HOSTFS_I(inode)->fd != -1) {
301 close_file(&HOSTFS_I(inode)->fd);
302 printk(KERN_DEBUG "Closing host fd in .destroy_inode\n");
303 }
304
305 kfree(HOSTFS_I(inode));
306 }
307
308 static void hostfs_read_inode(struct inode *inode)
309 {
310 read_inode(inode);
311 }
312
313 static const struct super_operations hostfs_sbops = {
314 .alloc_inode = hostfs_alloc_inode,
315 .drop_inode = generic_delete_inode,
316 .delete_inode = hostfs_delete_inode,
317 .destroy_inode = hostfs_destroy_inode,
318 .read_inode = hostfs_read_inode,
319 .statfs = hostfs_statfs,
320 };
321
322 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
323 {
324 void *dir;
325 char *name;
326 unsigned long long next, ino;
327 int error, len;
328
329 name = dentry_name(file->f_path.dentry, 0);
330 if(name == NULL)
331 return -ENOMEM;
332 dir = open_dir(name, &error);
333 kfree(name);
334 if(dir == NULL)
335 return -error;
336 next = file->f_pos;
337 while((name = read_dir(dir, &next, &ino, &len)) != NULL){
338 error = (*filldir)(ent, name, len, file->f_pos,
339 ino, DT_UNKNOWN);
340 if(error) break;
341 file->f_pos = next;
342 }
343 close_dir(dir);
344 return 0;
345 }
346
347 int hostfs_file_open(struct inode *ino, struct file *file)
348 {
349 char *name;
350 int mode = 0, r = 0, w = 0, fd;
351
352 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
353 if((mode & HOSTFS_I(ino)->mode) == mode)
354 return 0;
355
356 /* The file may already have been opened, but with the wrong access,
357 * so this resets things and reopens the file with the new access.
358 */
359 if(HOSTFS_I(ino)->fd != -1){
360 close_file(&HOSTFS_I(ino)->fd);
361 HOSTFS_I(ino)->fd = -1;
362 }
363
364 HOSTFS_I(ino)->mode |= mode;
365 if(HOSTFS_I(ino)->mode & FMODE_READ)
366 r = 1;
367 if(HOSTFS_I(ino)->mode & FMODE_WRITE)
368 w = 1;
369 if(w)
370 r = 1;
371
372 name = dentry_name(file->f_path.dentry, 0);
373 if(name == NULL)
374 return -ENOMEM;
375
376 fd = open_file(name, r, w, append);
377 kfree(name);
378 if(fd < 0)
379 return fd;
380 FILE_HOSTFS_I(file)->fd = fd;
381
382 return 0;
383 }
384
385 int hostfs_fsync(struct file *file, struct dentry *dentry, int datasync)
386 {
387 return fsync_file(HOSTFS_I(dentry->d_inode)->fd, datasync);
388 }
389
390 static const struct file_operations hostfs_file_fops = {
391 .llseek = generic_file_llseek,
392 .read = do_sync_read,
393 .splice_read = generic_file_splice_read,
394 .aio_read = generic_file_aio_read,
395 .aio_write = generic_file_aio_write,
396 .write = do_sync_write,
397 .mmap = generic_file_mmap,
398 .open = hostfs_file_open,
399 .release = NULL,
400 .fsync = hostfs_fsync,
401 };
402
403 static const struct file_operations hostfs_dir_fops = {
404 .llseek = generic_file_llseek,
405 .readdir = hostfs_readdir,
406 .read = generic_read_dir,
407 };
408
409 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
410 {
411 struct address_space *mapping = page->mapping;
412 struct inode *inode = mapping->host;
413 char *buffer;
414 unsigned long long base;
415 int count = PAGE_CACHE_SIZE;
416 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
417 int err;
418
419 if (page->index >= end_index)
420 count = inode->i_size & (PAGE_CACHE_SIZE-1);
421
422 buffer = kmap(page);
423 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
424
425 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
426 if(err != count){
427 ClearPageUptodate(page);
428 goto out;
429 }
430
431 if (base > inode->i_size)
432 inode->i_size = base;
433
434 if (PageError(page))
435 ClearPageError(page);
436 err = 0;
437
438 out:
439 kunmap(page);
440
441 unlock_page(page);
442 return err;
443 }
444
445 int hostfs_readpage(struct file *file, struct page *page)
446 {
447 char *buffer;
448 long long start;
449 int err = 0;
450
451 start = (long long) page->index << PAGE_CACHE_SHIFT;
452 buffer = kmap(page);
453 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
454 PAGE_CACHE_SIZE);
455 if(err < 0) goto out;
456
457 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
458
459 flush_dcache_page(page);
460 SetPageUptodate(page);
461 if (PageError(page)) ClearPageError(page);
462 err = 0;
463 out:
464 kunmap(page);
465 unlock_page(page);
466 return err;
467 }
468
469 int hostfs_prepare_write(struct file *file, struct page *page,
470 unsigned int from, unsigned int to)
471 {
472 char *buffer;
473 long long start, tmp;
474 int err;
475
476 start = (long long) page->index << PAGE_CACHE_SHIFT;
477 buffer = kmap(page);
478 if(from != 0){
479 tmp = start;
480 err = read_file(FILE_HOSTFS_I(file)->fd, &tmp, buffer,
481 from);
482 if(err < 0) goto out;
483 }
484 if(to != PAGE_CACHE_SIZE){
485 start += to;
486 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer + to,
487 PAGE_CACHE_SIZE - to);
488 if(err < 0) goto out;
489 }
490 err = 0;
491 out:
492 kunmap(page);
493 return err;
494 }
495
496 int hostfs_commit_write(struct file *file, struct page *page, unsigned from,
497 unsigned to)
498 {
499 struct address_space *mapping = page->mapping;
500 struct inode *inode = mapping->host;
501 char *buffer;
502 long long start;
503 int err = 0;
504
505 start = (((long long) page->index) << PAGE_CACHE_SHIFT) + from;
506 buffer = kmap(page);
507 err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from,
508 to - from);
509 if(err > 0) err = 0;
510
511 /* Actually, if !err, write_file has added to-from to start, so, despite
512 * the appearance, we are comparing i_size against the _last_ written
513 * location, as we should. */
514
515 if(!err && (start > inode->i_size))
516 inode->i_size = start;
517
518 kunmap(page);
519 return err;
520 }
521
522 static const struct address_space_operations hostfs_aops = {
523 .writepage = hostfs_writepage,
524 .readpage = hostfs_readpage,
525 .set_page_dirty = __set_page_dirty_nobuffers,
526 .prepare_write = hostfs_prepare_write,
527 .commit_write = hostfs_commit_write
528 };
529
530 static int init_inode(struct inode *inode, struct dentry *dentry)
531 {
532 char *name;
533 int type, err = -ENOMEM;
534 int maj, min;
535 dev_t rdev = 0;
536
537 if(dentry){
538 name = dentry_name(dentry, 0);
539 if(name == NULL)
540 goto out;
541 type = file_type(name, &maj, &min);
542 /*Reencode maj and min with the kernel encoding.*/
543 rdev = MKDEV(maj, min);
544 kfree(name);
545 }
546 else type = OS_TYPE_DIR;
547
548 err = 0;
549 if(type == OS_TYPE_SYMLINK)
550 inode->i_op = &page_symlink_inode_operations;
551 else if(type == OS_TYPE_DIR)
552 inode->i_op = &hostfs_dir_iops;
553 else inode->i_op = &hostfs_iops;
554
555 if(type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops;
556 else inode->i_fop = &hostfs_file_fops;
557
558 if(type == OS_TYPE_SYMLINK)
559 inode->i_mapping->a_ops = &hostfs_link_aops;
560 else inode->i_mapping->a_ops = &hostfs_aops;
561
562 switch (type) {
563 case OS_TYPE_CHARDEV:
564 init_special_inode(inode, S_IFCHR, rdev);
565 break;
566 case OS_TYPE_BLOCKDEV:
567 init_special_inode(inode, S_IFBLK, rdev);
568 break;
569 case OS_TYPE_FIFO:
570 init_special_inode(inode, S_IFIFO, 0);
571 break;
572 case OS_TYPE_SOCK:
573 init_special_inode(inode, S_IFSOCK, 0);
574 break;
575 }
576 out:
577 return err;
578 }
579
580 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
581 struct nameidata *nd)
582 {
583 struct inode *inode;
584 char *name;
585 int error, fd;
586
587 error = -ENOMEM;
588 inode = iget(dir->i_sb, 0);
589 if(inode == NULL) goto out;
590
591 error = init_inode(inode, dentry);
592 if(error)
593 goto out_put;
594
595 error = -ENOMEM;
596 name = dentry_name(dentry, 0);
597 if(name == NULL)
598 goto out_put;
599
600 fd = file_create(name,
601 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
602 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
603 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
604 if(fd < 0)
605 error = fd;
606 else error = read_name(inode, name);
607
608 kfree(name);
609 if(error)
610 goto out_put;
611
612 HOSTFS_I(inode)->fd = fd;
613 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
614 d_instantiate(dentry, inode);
615 return 0;
616
617 out_put:
618 iput(inode);
619 out:
620 return error;
621 }
622
623 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
624 struct nameidata *nd)
625 {
626 struct inode *inode;
627 char *name;
628 int err;
629
630 err = -ENOMEM;
631 inode = iget(ino->i_sb, 0);
632 if(inode == NULL)
633 goto out;
634
635 err = init_inode(inode, dentry);
636 if(err)
637 goto out_put;
638
639 err = -ENOMEM;
640 name = dentry_name(dentry, 0);
641 if(name == NULL)
642 goto out_put;
643
644 err = read_name(inode, name);
645 kfree(name);
646 if(err == -ENOENT){
647 iput(inode);
648 inode = NULL;
649 }
650 else if(err)
651 goto out_put;
652
653 d_add(dentry, inode);
654 dentry->d_op = &hostfs_dentry_ops;
655 return NULL;
656
657 out_put:
658 iput(inode);
659 out:
660 return ERR_PTR(err);
661 }
662
663 static char *inode_dentry_name(struct inode *ino, struct dentry *dentry)
664 {
665 char *file;
666 int len;
667
668 file = inode_name(ino, dentry->d_name.len + 1);
669 if(file == NULL)
670 return NULL;
671 strcat(file, "/");
672 len = strlen(file);
673 strncat(file, dentry->d_name.name, dentry->d_name.len);
674 file[len + dentry->d_name.len] = '\0';
675 return file;
676 }
677
678 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
679 {
680 char *from_name, *to_name;
681 int err;
682
683 if((from_name = inode_dentry_name(ino, from)) == NULL)
684 return -ENOMEM;
685 to_name = dentry_name(to, 0);
686 if(to_name == NULL){
687 kfree(from_name);
688 return -ENOMEM;
689 }
690 err = link_file(to_name, from_name);
691 kfree(from_name);
692 kfree(to_name);
693 return err;
694 }
695
696 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
697 {
698 char *file;
699 int err;
700
701 if((file = inode_dentry_name(ino, dentry)) == NULL)
702 return -ENOMEM;
703 if(append)
704 return -EPERM;
705
706 err = unlink_file(file);
707 kfree(file);
708 return err;
709 }
710
711 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
712 {
713 char *file;
714 int err;
715
716 if((file = inode_dentry_name(ino, dentry)) == NULL)
717 return -ENOMEM;
718 err = make_symlink(file, to);
719 kfree(file);
720 return err;
721 }
722
723 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
724 {
725 char *file;
726 int err;
727
728 if((file = inode_dentry_name(ino, dentry)) == NULL)
729 return -ENOMEM;
730 err = do_mkdir(file, mode);
731 kfree(file);
732 return err;
733 }
734
735 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
736 {
737 char *file;
738 int err;
739
740 if((file = inode_dentry_name(ino, dentry)) == NULL)
741 return -ENOMEM;
742 err = do_rmdir(file);
743 kfree(file);
744 return err;
745 }
746
747 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
748 {
749 struct inode *inode;
750 char *name;
751 int err = -ENOMEM;
752
753 inode = iget(dir->i_sb, 0);
754 if(inode == NULL)
755 goto out;
756
757 err = init_inode(inode, dentry);
758 if(err)
759 goto out_put;
760
761 err = -ENOMEM;
762 name = dentry_name(dentry, 0);
763 if(name == NULL)
764 goto out_put;
765
766 init_special_inode(inode, mode, dev);
767 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
768 if(err)
769 goto out_free;
770
771 err = read_name(inode, name);
772 kfree(name);
773 if(err)
774 goto out_put;
775
776 d_instantiate(dentry, inode);
777 return 0;
778
779 out_free:
780 kfree(name);
781 out_put:
782 iput(inode);
783 out:
784 return err;
785 }
786
787 int hostfs_rename(struct inode *from_ino, struct dentry *from,
788 struct inode *to_ino, struct dentry *to)
789 {
790 char *from_name, *to_name;
791 int err;
792
793 if((from_name = inode_dentry_name(from_ino, from)) == NULL)
794 return -ENOMEM;
795 if((to_name = inode_dentry_name(to_ino, to)) == NULL){
796 kfree(from_name);
797 return -ENOMEM;
798 }
799 err = rename_file(from_name, to_name);
800 kfree(from_name);
801 kfree(to_name);
802 return err;
803 }
804
805 int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd)
806 {
807 char *name;
808 int r = 0, w = 0, x = 0, err;
809
810 if (desired & MAY_READ) r = 1;
811 if (desired & MAY_WRITE) w = 1;
812 if (desired & MAY_EXEC) x = 1;
813 name = inode_name(ino, 0);
814 if (name == NULL)
815 return -ENOMEM;
816
817 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
818 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
819 err = 0;
820 else
821 err = access_file(name, r, w, x);
822 kfree(name);
823 if(!err)
824 err = generic_permission(ino, desired, NULL);
825 return err;
826 }
827
828 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
829 {
830 struct hostfs_iattr attrs;
831 char *name;
832 int err;
833
834 int fd = HOSTFS_I(dentry->d_inode)->fd;
835
836 err = inode_change_ok(dentry->d_inode, attr);
837 if (err)
838 return err;
839
840 if(append)
841 attr->ia_valid &= ~ATTR_SIZE;
842
843 attrs.ia_valid = 0;
844 if(attr->ia_valid & ATTR_MODE){
845 attrs.ia_valid |= HOSTFS_ATTR_MODE;
846 attrs.ia_mode = attr->ia_mode;
847 }
848 if(attr->ia_valid & ATTR_UID){
849 attrs.ia_valid |= HOSTFS_ATTR_UID;
850 attrs.ia_uid = attr->ia_uid;
851 }
852 if(attr->ia_valid & ATTR_GID){
853 attrs.ia_valid |= HOSTFS_ATTR_GID;
854 attrs.ia_gid = attr->ia_gid;
855 }
856 if(attr->ia_valid & ATTR_SIZE){
857 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
858 attrs.ia_size = attr->ia_size;
859 }
860 if(attr->ia_valid & ATTR_ATIME){
861 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
862 attrs.ia_atime = attr->ia_atime;
863 }
864 if(attr->ia_valid & ATTR_MTIME){
865 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
866 attrs.ia_mtime = attr->ia_mtime;
867 }
868 if(attr->ia_valid & ATTR_CTIME){
869 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
870 attrs.ia_ctime = attr->ia_ctime;
871 }
872 if(attr->ia_valid & ATTR_ATIME_SET){
873 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
874 }
875 if(attr->ia_valid & ATTR_MTIME_SET){
876 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
877 }
878 name = dentry_name(dentry, 0);
879 if(name == NULL)
880 return -ENOMEM;
881 err = set_attr(name, &attrs, fd);
882 kfree(name);
883 if(err)
884 return err;
885
886 return inode_setattr(dentry->d_inode, attr);
887 }
888
889 int hostfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
890 struct kstat *stat)
891 {
892 generic_fillattr(dentry->d_inode, stat);
893 return 0;
894 }
895
896 static const struct inode_operations hostfs_iops = {
897 .create = hostfs_create,
898 .link = hostfs_link,
899 .unlink = hostfs_unlink,
900 .symlink = hostfs_symlink,
901 .mkdir = hostfs_mkdir,
902 .rmdir = hostfs_rmdir,
903 .mknod = hostfs_mknod,
904 .rename = hostfs_rename,
905 .permission = hostfs_permission,
906 .setattr = hostfs_setattr,
907 .getattr = hostfs_getattr,
908 };
909
910 static const struct inode_operations hostfs_dir_iops = {
911 .create = hostfs_create,
912 .lookup = hostfs_lookup,
913 .link = hostfs_link,
914 .unlink = hostfs_unlink,
915 .symlink = hostfs_symlink,
916 .mkdir = hostfs_mkdir,
917 .rmdir = hostfs_rmdir,
918 .mknod = hostfs_mknod,
919 .rename = hostfs_rename,
920 .permission = hostfs_permission,
921 .setattr = hostfs_setattr,
922 .getattr = hostfs_getattr,
923 };
924
925 int hostfs_link_readpage(struct file *file, struct page *page)
926 {
927 char *buffer, *name;
928 int err;
929
930 buffer = kmap(page);
931 name = inode_name(page->mapping->host, 0);
932 if(name == NULL)
933 return -ENOMEM;
934 err = do_readlink(name, buffer, PAGE_CACHE_SIZE);
935 kfree(name);
936 if(err == PAGE_CACHE_SIZE)
937 err = -E2BIG;
938 else if(err > 0){
939 flush_dcache_page(page);
940 SetPageUptodate(page);
941 if (PageError(page)) ClearPageError(page);
942 err = 0;
943 }
944 kunmap(page);
945 unlock_page(page);
946 return err;
947 }
948
949 static const struct address_space_operations hostfs_link_aops = {
950 .readpage = hostfs_link_readpage,
951 };
952
953 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
954 {
955 struct inode *root_inode;
956 char *host_root_path, *req_root = d;
957 int err;
958
959 sb->s_blocksize = 1024;
960 sb->s_blocksize_bits = 10;
961 sb->s_magic = HOSTFS_SUPER_MAGIC;
962 sb->s_op = &hostfs_sbops;
963
964 /* NULL is printed as <NULL> by sprintf: avoid that. */
965 if (req_root == NULL)
966 req_root = "";
967
968 err = -ENOMEM;
969 host_root_path = kmalloc(strlen(root_ino) + 1
970 + strlen(req_root) + 1, GFP_KERNEL);
971 if(host_root_path == NULL)
972 goto out;
973
974 sprintf(host_root_path, "%s/%s", root_ino, req_root);
975
976 root_inode = iget(sb, 0);
977 if(root_inode == NULL)
978 goto out_free;
979
980 err = init_inode(root_inode, NULL);
981 if(err)
982 goto out_put;
983
984 HOSTFS_I(root_inode)->host_filename = host_root_path;
985 /* Avoid that in the error path, iput(root_inode) frees again
986 * host_root_path through hostfs_destroy_inode! */
987 host_root_path = NULL;
988
989 err = -ENOMEM;
990 sb->s_root = d_alloc_root(root_inode);
991 if(sb->s_root == NULL)
992 goto out_put;
993
994 err = read_inode(root_inode);
995 if(err){
996 /* No iput in this case because the dput does that for us */
997 dput(sb->s_root);
998 sb->s_root = NULL;
999 goto out;
1000 }
1001
1002 return 0;
1003
1004 out_put:
1005 iput(root_inode);
1006 out_free:
1007 kfree(host_root_path);
1008 out:
1009 return err;
1010 }
1011
1012 static int hostfs_read_sb(struct file_system_type *type,
1013 int flags, const char *dev_name,
1014 void *data, struct vfsmount *mnt)
1015 {
1016 return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt);
1017 }
1018
1019 static struct file_system_type hostfs_type = {
1020 .owner = THIS_MODULE,
1021 .name = "hostfs",
1022 .get_sb = hostfs_read_sb,
1023 .kill_sb = kill_anon_super,
1024 .fs_flags = 0,
1025 };
1026
1027 static int __init init_hostfs(void)
1028 {
1029 return register_filesystem(&hostfs_type);
1030 }
1031
1032 static void __exit exit_hostfs(void)
1033 {
1034 unregister_filesystem(&hostfs_type);
1035 }
1036
1037 module_init(init_hostfs)
1038 module_exit(exit_hostfs)
1039 MODULE_LICENSE("GPL");
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