Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * fs/libfs.c | |
3 | * Library for filesystems writers. | |
4 | */ | |
5 | ||
6 | #include <linux/module.h> | |
7 | #include <linux/pagemap.h> | |
8 | #include <linux/mount.h> | |
9 | #include <linux/vfs.h> | |
10 | #include <asm/uaccess.h> | |
11 | ||
12 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
13 | struct kstat *stat) | |
14 | { | |
15 | struct inode *inode = dentry->d_inode; | |
16 | generic_fillattr(inode, stat); | |
17 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); | |
18 | return 0; | |
19 | } | |
20 | ||
21 | int simple_statfs(struct super_block *sb, struct kstatfs *buf) | |
22 | { | |
23 | buf->f_type = sb->s_magic; | |
24 | buf->f_bsize = PAGE_CACHE_SIZE; | |
25 | buf->f_namelen = NAME_MAX; | |
26 | return 0; | |
27 | } | |
28 | ||
29 | /* | |
30 | * Retaining negative dentries for an in-memory filesystem just wastes | |
31 | * memory and lookup time: arrange for them to be deleted immediately. | |
32 | */ | |
33 | static int simple_delete_dentry(struct dentry *dentry) | |
34 | { | |
35 | return 1; | |
36 | } | |
37 | ||
38 | /* | |
39 | * Lookup the data. This is trivial - if the dentry didn't already | |
40 | * exist, we know it is negative. Set d_op to delete negative dentries. | |
41 | */ | |
42 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) | |
43 | { | |
44 | static struct dentry_operations simple_dentry_operations = { | |
45 | .d_delete = simple_delete_dentry, | |
46 | }; | |
47 | ||
48 | if (dentry->d_name.len > NAME_MAX) | |
49 | return ERR_PTR(-ENAMETOOLONG); | |
50 | dentry->d_op = &simple_dentry_operations; | |
51 | d_add(dentry, NULL); | |
52 | return NULL; | |
53 | } | |
54 | ||
55 | int simple_sync_file(struct file * file, struct dentry *dentry, int datasync) | |
56 | { | |
57 | return 0; | |
58 | } | |
59 | ||
60 | int dcache_dir_open(struct inode *inode, struct file *file) | |
61 | { | |
62 | static struct qstr cursor_name = {.len = 1, .name = "."}; | |
63 | ||
64 | file->private_data = d_alloc(file->f_dentry, &cursor_name); | |
65 | ||
66 | return file->private_data ? 0 : -ENOMEM; | |
67 | } | |
68 | ||
69 | int dcache_dir_close(struct inode *inode, struct file *file) | |
70 | { | |
71 | dput(file->private_data); | |
72 | return 0; | |
73 | } | |
74 | ||
75 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) | |
76 | { | |
77 | down(&file->f_dentry->d_inode->i_sem); | |
78 | switch (origin) { | |
79 | case 1: | |
80 | offset += file->f_pos; | |
81 | case 0: | |
82 | if (offset >= 0) | |
83 | break; | |
84 | default: | |
85 | up(&file->f_dentry->d_inode->i_sem); | |
86 | return -EINVAL; | |
87 | } | |
88 | if (offset != file->f_pos) { | |
89 | file->f_pos = offset; | |
90 | if (file->f_pos >= 2) { | |
91 | struct list_head *p; | |
92 | struct dentry *cursor = file->private_data; | |
93 | loff_t n = file->f_pos - 2; | |
94 | ||
95 | spin_lock(&dcache_lock); | |
96 | list_del(&cursor->d_child); | |
97 | p = file->f_dentry->d_subdirs.next; | |
98 | while (n && p != &file->f_dentry->d_subdirs) { | |
99 | struct dentry *next; | |
100 | next = list_entry(p, struct dentry, d_child); | |
101 | if (!d_unhashed(next) && next->d_inode) | |
102 | n--; | |
103 | p = p->next; | |
104 | } | |
105 | list_add_tail(&cursor->d_child, p); | |
106 | spin_unlock(&dcache_lock); | |
107 | } | |
108 | } | |
109 | up(&file->f_dentry->d_inode->i_sem); | |
110 | return offset; | |
111 | } | |
112 | ||
113 | /* Relationship between i_mode and the DT_xxx types */ | |
114 | static inline unsigned char dt_type(struct inode *inode) | |
115 | { | |
116 | return (inode->i_mode >> 12) & 15; | |
117 | } | |
118 | ||
119 | /* | |
120 | * Directory is locked and all positive dentries in it are safe, since | |
121 | * for ramfs-type trees they can't go away without unlink() or rmdir(), | |
122 | * both impossible due to the lock on directory. | |
123 | */ | |
124 | ||
125 | int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) | |
126 | { | |
127 | struct dentry *dentry = filp->f_dentry; | |
128 | struct dentry *cursor = filp->private_data; | |
129 | struct list_head *p, *q = &cursor->d_child; | |
130 | ino_t ino; | |
131 | int i = filp->f_pos; | |
132 | ||
133 | switch (i) { | |
134 | case 0: | |
135 | ino = dentry->d_inode->i_ino; | |
136 | if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) | |
137 | break; | |
138 | filp->f_pos++; | |
139 | i++; | |
140 | /* fallthrough */ | |
141 | case 1: | |
142 | ino = parent_ino(dentry); | |
143 | if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) | |
144 | break; | |
145 | filp->f_pos++; | |
146 | i++; | |
147 | /* fallthrough */ | |
148 | default: | |
149 | spin_lock(&dcache_lock); | |
150 | if (filp->f_pos == 2) { | |
151 | list_del(q); | |
152 | list_add(q, &dentry->d_subdirs); | |
153 | } | |
154 | for (p=q->next; p != &dentry->d_subdirs; p=p->next) { | |
155 | struct dentry *next; | |
156 | next = list_entry(p, struct dentry, d_child); | |
157 | if (d_unhashed(next) || !next->d_inode) | |
158 | continue; | |
159 | ||
160 | spin_unlock(&dcache_lock); | |
161 | if (filldir(dirent, next->d_name.name, next->d_name.len, filp->f_pos, next->d_inode->i_ino, dt_type(next->d_inode)) < 0) | |
162 | return 0; | |
163 | spin_lock(&dcache_lock); | |
164 | /* next is still alive */ | |
165 | list_del(q); | |
166 | list_add(q, p); | |
167 | p = q; | |
168 | filp->f_pos++; | |
169 | } | |
170 | spin_unlock(&dcache_lock); | |
171 | } | |
172 | return 0; | |
173 | } | |
174 | ||
175 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) | |
176 | { | |
177 | return -EISDIR; | |
178 | } | |
179 | ||
180 | struct file_operations simple_dir_operations = { | |
181 | .open = dcache_dir_open, | |
182 | .release = dcache_dir_close, | |
183 | .llseek = dcache_dir_lseek, | |
184 | .read = generic_read_dir, | |
185 | .readdir = dcache_readdir, | |
186 | }; | |
187 | ||
188 | struct inode_operations simple_dir_inode_operations = { | |
189 | .lookup = simple_lookup, | |
190 | }; | |
191 | ||
192 | /* | |
193 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that | |
194 | * will never be mountable) | |
195 | */ | |
196 | struct super_block * | |
197 | get_sb_pseudo(struct file_system_type *fs_type, char *name, | |
198 | struct super_operations *ops, unsigned long magic) | |
199 | { | |
200 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
201 | static struct super_operations default_ops = {.statfs = simple_statfs}; | |
202 | struct dentry *dentry; | |
203 | struct inode *root; | |
204 | struct qstr d_name = {.name = name, .len = strlen(name)}; | |
205 | ||
206 | if (IS_ERR(s)) | |
207 | return s; | |
208 | ||
209 | s->s_flags = MS_NOUSER; | |
210 | s->s_maxbytes = ~0ULL; | |
211 | s->s_blocksize = 1024; | |
212 | s->s_blocksize_bits = 10; | |
213 | s->s_magic = magic; | |
214 | s->s_op = ops ? ops : &default_ops; | |
215 | s->s_time_gran = 1; | |
216 | root = new_inode(s); | |
217 | if (!root) | |
218 | goto Enomem; | |
219 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; | |
220 | root->i_uid = root->i_gid = 0; | |
221 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; | |
222 | dentry = d_alloc(NULL, &d_name); | |
223 | if (!dentry) { | |
224 | iput(root); | |
225 | goto Enomem; | |
226 | } | |
227 | dentry->d_sb = s; | |
228 | dentry->d_parent = dentry; | |
229 | d_instantiate(dentry, root); | |
230 | s->s_root = dentry; | |
231 | s->s_flags |= MS_ACTIVE; | |
232 | return s; | |
233 | ||
234 | Enomem: | |
235 | up_write(&s->s_umount); | |
236 | deactivate_super(s); | |
237 | return ERR_PTR(-ENOMEM); | |
238 | } | |
239 | ||
240 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
241 | { | |
242 | struct inode *inode = old_dentry->d_inode; | |
243 | ||
244 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
245 | inode->i_nlink++; | |
246 | atomic_inc(&inode->i_count); | |
247 | dget(dentry); | |
248 | d_instantiate(dentry, inode); | |
249 | return 0; | |
250 | } | |
251 | ||
252 | static inline int simple_positive(struct dentry *dentry) | |
253 | { | |
254 | return dentry->d_inode && !d_unhashed(dentry); | |
255 | } | |
256 | ||
257 | int simple_empty(struct dentry *dentry) | |
258 | { | |
259 | struct dentry *child; | |
260 | int ret = 0; | |
261 | ||
262 | spin_lock(&dcache_lock); | |
263 | list_for_each_entry(child, &dentry->d_subdirs, d_child) | |
264 | if (simple_positive(child)) | |
265 | goto out; | |
266 | ret = 1; | |
267 | out: | |
268 | spin_unlock(&dcache_lock); | |
269 | return ret; | |
270 | } | |
271 | ||
272 | int simple_unlink(struct inode *dir, struct dentry *dentry) | |
273 | { | |
274 | struct inode *inode = dentry->d_inode; | |
275 | ||
276 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
277 | inode->i_nlink--; | |
278 | dput(dentry); | |
279 | return 0; | |
280 | } | |
281 | ||
282 | int simple_rmdir(struct inode *dir, struct dentry *dentry) | |
283 | { | |
284 | if (!simple_empty(dentry)) | |
285 | return -ENOTEMPTY; | |
286 | ||
287 | dentry->d_inode->i_nlink--; | |
288 | simple_unlink(dir, dentry); | |
289 | dir->i_nlink--; | |
290 | return 0; | |
291 | } | |
292 | ||
293 | int simple_rename(struct inode *old_dir, struct dentry *old_dentry, | |
294 | struct inode *new_dir, struct dentry *new_dentry) | |
295 | { | |
296 | struct inode *inode = old_dentry->d_inode; | |
297 | int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); | |
298 | ||
299 | if (!simple_empty(new_dentry)) | |
300 | return -ENOTEMPTY; | |
301 | ||
302 | if (new_dentry->d_inode) { | |
303 | simple_unlink(new_dir, new_dentry); | |
304 | if (they_are_dirs) | |
305 | old_dir->i_nlink--; | |
306 | } else if (they_are_dirs) { | |
307 | old_dir->i_nlink--; | |
308 | new_dir->i_nlink++; | |
309 | } | |
310 | ||
311 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = | |
312 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; | |
313 | ||
314 | return 0; | |
315 | } | |
316 | ||
317 | int simple_readpage(struct file *file, struct page *page) | |
318 | { | |
319 | void *kaddr; | |
320 | ||
321 | if (PageUptodate(page)) | |
322 | goto out; | |
323 | ||
324 | kaddr = kmap_atomic(page, KM_USER0); | |
325 | memset(kaddr, 0, PAGE_CACHE_SIZE); | |
326 | kunmap_atomic(kaddr, KM_USER0); | |
327 | flush_dcache_page(page); | |
328 | SetPageUptodate(page); | |
329 | out: | |
330 | unlock_page(page); | |
331 | return 0; | |
332 | } | |
333 | ||
334 | int simple_prepare_write(struct file *file, struct page *page, | |
335 | unsigned from, unsigned to) | |
336 | { | |
337 | if (!PageUptodate(page)) { | |
338 | if (to - from != PAGE_CACHE_SIZE) { | |
339 | void *kaddr = kmap_atomic(page, KM_USER0); | |
340 | memset(kaddr, 0, from); | |
341 | memset(kaddr + to, 0, PAGE_CACHE_SIZE - to); | |
342 | flush_dcache_page(page); | |
343 | kunmap_atomic(kaddr, KM_USER0); | |
344 | } | |
345 | SetPageUptodate(page); | |
346 | } | |
347 | return 0; | |
348 | } | |
349 | ||
350 | int simple_commit_write(struct file *file, struct page *page, | |
351 | unsigned offset, unsigned to) | |
352 | { | |
353 | struct inode *inode = page->mapping->host; | |
354 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
355 | ||
356 | /* | |
357 | * No need to use i_size_read() here, the i_size | |
358 | * cannot change under us because we hold the i_sem. | |
359 | */ | |
360 | if (pos > inode->i_size) | |
361 | i_size_write(inode, pos); | |
362 | set_page_dirty(page); | |
363 | return 0; | |
364 | } | |
365 | ||
366 | int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files) | |
367 | { | |
368 | static struct super_operations s_ops = {.statfs = simple_statfs}; | |
369 | struct inode *inode; | |
370 | struct dentry *root; | |
371 | struct dentry *dentry; | |
372 | int i; | |
373 | ||
374 | s->s_blocksize = PAGE_CACHE_SIZE; | |
375 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
376 | s->s_magic = magic; | |
377 | s->s_op = &s_ops; | |
378 | s->s_time_gran = 1; | |
379 | ||
380 | inode = new_inode(s); | |
381 | if (!inode) | |
382 | return -ENOMEM; | |
383 | inode->i_mode = S_IFDIR | 0755; | |
384 | inode->i_uid = inode->i_gid = 0; | |
385 | inode->i_blksize = PAGE_CACHE_SIZE; | |
386 | inode->i_blocks = 0; | |
387 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
388 | inode->i_op = &simple_dir_inode_operations; | |
389 | inode->i_fop = &simple_dir_operations; | |
390 | root = d_alloc_root(inode); | |
391 | if (!root) { | |
392 | iput(inode); | |
393 | return -ENOMEM; | |
394 | } | |
395 | for (i = 0; !files->name || files->name[0]; i++, files++) { | |
396 | if (!files->name) | |
397 | continue; | |
398 | dentry = d_alloc_name(root, files->name); | |
399 | if (!dentry) | |
400 | goto out; | |
401 | inode = new_inode(s); | |
402 | if (!inode) | |
403 | goto out; | |
404 | inode->i_mode = S_IFREG | files->mode; | |
405 | inode->i_uid = inode->i_gid = 0; | |
406 | inode->i_blksize = PAGE_CACHE_SIZE; | |
407 | inode->i_blocks = 0; | |
408 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
409 | inode->i_fop = files->ops; | |
410 | inode->i_ino = i; | |
411 | d_add(dentry, inode); | |
412 | } | |
413 | s->s_root = root; | |
414 | return 0; | |
415 | out: | |
416 | d_genocide(root); | |
417 | dput(root); | |
418 | return -ENOMEM; | |
419 | } | |
420 | ||
421 | static DEFINE_SPINLOCK(pin_fs_lock); | |
422 | ||
423 | int simple_pin_fs(char *name, struct vfsmount **mount, int *count) | |
424 | { | |
425 | struct vfsmount *mnt = NULL; | |
426 | spin_lock(&pin_fs_lock); | |
427 | if (unlikely(!*mount)) { | |
428 | spin_unlock(&pin_fs_lock); | |
429 | mnt = do_kern_mount(name, 0, name, NULL); | |
430 | if (IS_ERR(mnt)) | |
431 | return PTR_ERR(mnt); | |
432 | spin_lock(&pin_fs_lock); | |
433 | if (!*mount) | |
434 | *mount = mnt; | |
435 | } | |
436 | mntget(*mount); | |
437 | ++*count; | |
438 | spin_unlock(&pin_fs_lock); | |
439 | mntput(mnt); | |
440 | return 0; | |
441 | } | |
442 | ||
443 | void simple_release_fs(struct vfsmount **mount, int *count) | |
444 | { | |
445 | struct vfsmount *mnt; | |
446 | spin_lock(&pin_fs_lock); | |
447 | mnt = *mount; | |
448 | if (!--*count) | |
449 | *mount = NULL; | |
450 | spin_unlock(&pin_fs_lock); | |
451 | mntput(mnt); | |
452 | } | |
453 | ||
454 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, | |
455 | const void *from, size_t available) | |
456 | { | |
457 | loff_t pos = *ppos; | |
458 | if (pos < 0) | |
459 | return -EINVAL; | |
460 | if (pos >= available) | |
461 | return 0; | |
462 | if (count > available - pos) | |
463 | count = available - pos; | |
464 | if (copy_to_user(to, from + pos, count)) | |
465 | return -EFAULT; | |
466 | *ppos = pos + count; | |
467 | return count; | |
468 | } | |
469 | ||
470 | /* | |
471 | * Transaction based IO. | |
472 | * The file expects a single write which triggers the transaction, and then | |
473 | * possibly a read which collects the result - which is stored in a | |
474 | * file-local buffer. | |
475 | */ | |
476 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) | |
477 | { | |
478 | struct simple_transaction_argresp *ar; | |
479 | static DEFINE_SPINLOCK(simple_transaction_lock); | |
480 | ||
481 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) | |
482 | return ERR_PTR(-EFBIG); | |
483 | ||
484 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); | |
485 | if (!ar) | |
486 | return ERR_PTR(-ENOMEM); | |
487 | ||
488 | spin_lock(&simple_transaction_lock); | |
489 | ||
490 | /* only one write allowed per open */ | |
491 | if (file->private_data) { | |
492 | spin_unlock(&simple_transaction_lock); | |
493 | free_page((unsigned long)ar); | |
494 | return ERR_PTR(-EBUSY); | |
495 | } | |
496 | ||
497 | file->private_data = ar; | |
498 | ||
499 | spin_unlock(&simple_transaction_lock); | |
500 | ||
501 | if (copy_from_user(ar->data, buf, size)) | |
502 | return ERR_PTR(-EFAULT); | |
503 | ||
504 | return ar->data; | |
505 | } | |
506 | ||
507 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) | |
508 | { | |
509 | struct simple_transaction_argresp *ar = file->private_data; | |
510 | ||
511 | if (!ar) | |
512 | return 0; | |
513 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); | |
514 | } | |
515 | ||
516 | int simple_transaction_release(struct inode *inode, struct file *file) | |
517 | { | |
518 | free_page((unsigned long)file->private_data); | |
519 | return 0; | |
520 | } | |
521 | ||
522 | EXPORT_SYMBOL(dcache_dir_close); | |
523 | EXPORT_SYMBOL(dcache_dir_lseek); | |
524 | EXPORT_SYMBOL(dcache_dir_open); | |
525 | EXPORT_SYMBOL(dcache_readdir); | |
526 | EXPORT_SYMBOL(generic_read_dir); | |
527 | EXPORT_SYMBOL(get_sb_pseudo); | |
528 | EXPORT_SYMBOL(simple_commit_write); | |
529 | EXPORT_SYMBOL(simple_dir_inode_operations); | |
530 | EXPORT_SYMBOL(simple_dir_operations); | |
531 | EXPORT_SYMBOL(simple_empty); | |
532 | EXPORT_SYMBOL(d_alloc_name); | |
533 | EXPORT_SYMBOL(simple_fill_super); | |
534 | EXPORT_SYMBOL(simple_getattr); | |
535 | EXPORT_SYMBOL(simple_link); | |
536 | EXPORT_SYMBOL(simple_lookup); | |
537 | EXPORT_SYMBOL(simple_pin_fs); | |
538 | EXPORT_SYMBOL(simple_prepare_write); | |
539 | EXPORT_SYMBOL(simple_readpage); | |
540 | EXPORT_SYMBOL(simple_release_fs); | |
541 | EXPORT_SYMBOL(simple_rename); | |
542 | EXPORT_SYMBOL(simple_rmdir); | |
543 | EXPORT_SYMBOL(simple_statfs); | |
544 | EXPORT_SYMBOL(simple_sync_file); | |
545 | EXPORT_SYMBOL(simple_unlink); | |
546 | EXPORT_SYMBOL(simple_read_from_buffer); | |
547 | EXPORT_SYMBOL(simple_transaction_get); | |
548 | EXPORT_SYMBOL(simple_transaction_read); | |
549 | EXPORT_SYMBOL(simple_transaction_release); |