Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/libfs.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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File size: 13217 byte(s)
Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 13217 byte(s)
Tag kernel26-2.6.12-alx-r9
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); |