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Source at commit 6c17a31f1fc515425221067cb3ece599c09dbc5d created 12 years 8 months ago. By Werner Almesberger, atusb, atben: moved from spi/ to ieee802154/; renamed atusb to spi_atusb | |
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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/slab.h> |
9 | #include <linux/mount.h> |
10 | #include <linux/vfs.h> |
11 | #include <linux/quotaops.h> |
12 | #include <linux/mutex.h> |
13 | #include <linux/exportfs.h> |
14 | #include <linux/writeback.h> |
15 | #include <linux/buffer_head.h> |
16 | |
17 | #include <asm/uaccess.h> |
18 | |
19 | static inline int simple_positive(struct dentry *dentry) |
20 | { |
21 | return dentry->d_inode && !d_unhashed(dentry); |
22 | } |
23 | |
24 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, |
25 | struct kstat *stat) |
26 | { |
27 | struct inode *inode = dentry->d_inode; |
28 | generic_fillattr(inode, stat); |
29 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); |
30 | return 0; |
31 | } |
32 | |
33 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
34 | { |
35 | buf->f_type = dentry->d_sb->s_magic; |
36 | buf->f_bsize = PAGE_CACHE_SIZE; |
37 | buf->f_namelen = NAME_MAX; |
38 | return 0; |
39 | } |
40 | |
41 | /* |
42 | * Retaining negative dentries for an in-memory filesystem just wastes |
43 | * memory and lookup time: arrange for them to be deleted immediately. |
44 | */ |
45 | static int simple_delete_dentry(const struct dentry *dentry) |
46 | { |
47 | return 1; |
48 | } |
49 | |
50 | /* |
51 | * Lookup the data. This is trivial - if the dentry didn't already |
52 | * exist, we know it is negative. Set d_op to delete negative dentries. |
53 | */ |
54 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) |
55 | { |
56 | static const struct dentry_operations simple_dentry_operations = { |
57 | .d_delete = simple_delete_dentry, |
58 | }; |
59 | |
60 | if (dentry->d_name.len > NAME_MAX) |
61 | return ERR_PTR(-ENAMETOOLONG); |
62 | d_set_d_op(dentry, &simple_dentry_operations); |
63 | d_add(dentry, NULL); |
64 | return NULL; |
65 | } |
66 | |
67 | int dcache_dir_open(struct inode *inode, struct file *file) |
68 | { |
69 | static struct qstr cursor_name = {.len = 1, .name = "."}; |
70 | |
71 | file->private_data = d_alloc(file->f_path.dentry, &cursor_name); |
72 | |
73 | return file->private_data ? 0 : -ENOMEM; |
74 | } |
75 | |
76 | int dcache_dir_close(struct inode *inode, struct file *file) |
77 | { |
78 | dput(file->private_data); |
79 | return 0; |
80 | } |
81 | |
82 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) |
83 | { |
84 | struct dentry *dentry = file->f_path.dentry; |
85 | mutex_lock(&dentry->d_inode->i_mutex); |
86 | switch (origin) { |
87 | case 1: |
88 | offset += file->f_pos; |
89 | case 0: |
90 | if (offset >= 0) |
91 | break; |
92 | default: |
93 | mutex_unlock(&dentry->d_inode->i_mutex); |
94 | return -EINVAL; |
95 | } |
96 | if (offset != file->f_pos) { |
97 | file->f_pos = offset; |
98 | if (file->f_pos >= 2) { |
99 | struct list_head *p; |
100 | struct dentry *cursor = file->private_data; |
101 | loff_t n = file->f_pos - 2; |
102 | |
103 | spin_lock(&dentry->d_lock); |
104 | /* d_lock not required for cursor */ |
105 | list_del(&cursor->d_u.d_child); |
106 | p = dentry->d_subdirs.next; |
107 | while (n && p != &dentry->d_subdirs) { |
108 | struct dentry *next; |
109 | next = list_entry(p, struct dentry, d_u.d_child); |
110 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
111 | if (simple_positive(next)) |
112 | n--; |
113 | spin_unlock(&next->d_lock); |
114 | p = p->next; |
115 | } |
116 | list_add_tail(&cursor->d_u.d_child, p); |
117 | spin_unlock(&dentry->d_lock); |
118 | } |
119 | } |
120 | mutex_unlock(&dentry->d_inode->i_mutex); |
121 | return offset; |
122 | } |
123 | |
124 | /* Relationship between i_mode and the DT_xxx types */ |
125 | static inline unsigned char dt_type(struct inode *inode) |
126 | { |
127 | return (inode->i_mode >> 12) & 15; |
128 | } |
129 | |
130 | /* |
131 | * Directory is locked and all positive dentries in it are safe, since |
132 | * for ramfs-type trees they can't go away without unlink() or rmdir(), |
133 | * both impossible due to the lock on directory. |
134 | */ |
135 | |
136 | int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) |
137 | { |
138 | struct dentry *dentry = filp->f_path.dentry; |
139 | struct dentry *cursor = filp->private_data; |
140 | struct list_head *p, *q = &cursor->d_u.d_child; |
141 | ino_t ino; |
142 | int i = filp->f_pos; |
143 | |
144 | switch (i) { |
145 | case 0: |
146 | ino = dentry->d_inode->i_ino; |
147 | if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) |
148 | break; |
149 | filp->f_pos++; |
150 | i++; |
151 | /* fallthrough */ |
152 | case 1: |
153 | ino = parent_ino(dentry); |
154 | if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) |
155 | break; |
156 | filp->f_pos++; |
157 | i++; |
158 | /* fallthrough */ |
159 | default: |
160 | spin_lock(&dentry->d_lock); |
161 | if (filp->f_pos == 2) |
162 | list_move(q, &dentry->d_subdirs); |
163 | |
164 | for (p=q->next; p != &dentry->d_subdirs; p=p->next) { |
165 | struct dentry *next; |
166 | next = list_entry(p, struct dentry, d_u.d_child); |
167 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
168 | if (!simple_positive(next)) { |
169 | spin_unlock(&next->d_lock); |
170 | continue; |
171 | } |
172 | |
173 | spin_unlock(&next->d_lock); |
174 | spin_unlock(&dentry->d_lock); |
175 | if (filldir(dirent, next->d_name.name, |
176 | next->d_name.len, filp->f_pos, |
177 | next->d_inode->i_ino, |
178 | dt_type(next->d_inode)) < 0) |
179 | return 0; |
180 | spin_lock(&dentry->d_lock); |
181 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
182 | /* next is still alive */ |
183 | list_move(q, p); |
184 | spin_unlock(&next->d_lock); |
185 | p = q; |
186 | filp->f_pos++; |
187 | } |
188 | spin_unlock(&dentry->d_lock); |
189 | } |
190 | return 0; |
191 | } |
192 | |
193 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) |
194 | { |
195 | return -EISDIR; |
196 | } |
197 | |
198 | const struct file_operations simple_dir_operations = { |
199 | .open = dcache_dir_open, |
200 | .release = dcache_dir_close, |
201 | .llseek = dcache_dir_lseek, |
202 | .read = generic_read_dir, |
203 | .readdir = dcache_readdir, |
204 | .fsync = noop_fsync, |
205 | }; |
206 | |
207 | const struct inode_operations simple_dir_inode_operations = { |
208 | .lookup = simple_lookup, |
209 | }; |
210 | |
211 | static const struct super_operations simple_super_operations = { |
212 | .statfs = simple_statfs, |
213 | }; |
214 | |
215 | /* |
216 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that |
217 | * will never be mountable) |
218 | */ |
219 | struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name, |
220 | const struct super_operations *ops, |
221 | const struct dentry_operations *dops, unsigned long magic) |
222 | { |
223 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); |
224 | struct dentry *dentry; |
225 | struct inode *root; |
226 | struct qstr d_name = {.name = name, .len = strlen(name)}; |
227 | |
228 | if (IS_ERR(s)) |
229 | return ERR_CAST(s); |
230 | |
231 | s->s_flags = MS_NOUSER; |
232 | s->s_maxbytes = MAX_LFS_FILESIZE; |
233 | s->s_blocksize = PAGE_SIZE; |
234 | s->s_blocksize_bits = PAGE_SHIFT; |
235 | s->s_magic = magic; |
236 | s->s_op = ops ? ops : &simple_super_operations; |
237 | s->s_time_gran = 1; |
238 | root = new_inode(s); |
239 | if (!root) |
240 | goto Enomem; |
241 | /* |
242 | * since this is the first inode, make it number 1. New inodes created |
243 | * after this must take care not to collide with it (by passing |
244 | * max_reserved of 1 to iunique). |
245 | */ |
246 | root->i_ino = 1; |
247 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
248 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; |
249 | dentry = d_alloc(NULL, &d_name); |
250 | if (!dentry) { |
251 | iput(root); |
252 | goto Enomem; |
253 | } |
254 | dentry->d_sb = s; |
255 | dentry->d_parent = dentry; |
256 | d_instantiate(dentry, root); |
257 | s->s_root = dentry; |
258 | s->s_d_op = dops; |
259 | s->s_flags |= MS_ACTIVE; |
260 | return dget(s->s_root); |
261 | |
262 | Enomem: |
263 | deactivate_locked_super(s); |
264 | return ERR_PTR(-ENOMEM); |
265 | } |
266 | |
267 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
268 | { |
269 | struct inode *inode = old_dentry->d_inode; |
270 | |
271 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
272 | inc_nlink(inode); |
273 | ihold(inode); |
274 | dget(dentry); |
275 | d_instantiate(dentry, inode); |
276 | return 0; |
277 | } |
278 | |
279 | int simple_empty(struct dentry *dentry) |
280 | { |
281 | struct dentry *child; |
282 | int ret = 0; |
283 | |
284 | spin_lock(&dentry->d_lock); |
285 | list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) { |
286 | spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); |
287 | if (simple_positive(child)) { |
288 | spin_unlock(&child->d_lock); |
289 | goto out; |
290 | } |
291 | spin_unlock(&child->d_lock); |
292 | } |
293 | ret = 1; |
294 | out: |
295 | spin_unlock(&dentry->d_lock); |
296 | return ret; |
297 | } |
298 | |
299 | int simple_unlink(struct inode *dir, struct dentry *dentry) |
300 | { |
301 | struct inode *inode = dentry->d_inode; |
302 | |
303 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
304 | drop_nlink(inode); |
305 | dput(dentry); |
306 | return 0; |
307 | } |
308 | |
309 | int simple_rmdir(struct inode *dir, struct dentry *dentry) |
310 | { |
311 | if (!simple_empty(dentry)) |
312 | return -ENOTEMPTY; |
313 | |
314 | drop_nlink(dentry->d_inode); |
315 | simple_unlink(dir, dentry); |
316 | drop_nlink(dir); |
317 | return 0; |
318 | } |
319 | |
320 | int simple_rename(struct inode *old_dir, struct dentry *old_dentry, |
321 | struct inode *new_dir, struct dentry *new_dentry) |
322 | { |
323 | struct inode *inode = old_dentry->d_inode; |
324 | int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); |
325 | |
326 | if (!simple_empty(new_dentry)) |
327 | return -ENOTEMPTY; |
328 | |
329 | if (new_dentry->d_inode) { |
330 | simple_unlink(new_dir, new_dentry); |
331 | if (they_are_dirs) |
332 | drop_nlink(old_dir); |
333 | } else if (they_are_dirs) { |
334 | drop_nlink(old_dir); |
335 | inc_nlink(new_dir); |
336 | } |
337 | |
338 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = |
339 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; |
340 | |
341 | return 0; |
342 | } |
343 | |
344 | /** |
345 | * simple_setattr - setattr for simple filesystem |
346 | * @dentry: dentry |
347 | * @iattr: iattr structure |
348 | * |
349 | * Returns 0 on success, -error on failure. |
350 | * |
351 | * simple_setattr is a simple ->setattr implementation without a proper |
352 | * implementation of size changes. |
353 | * |
354 | * It can either be used for in-memory filesystems or special files |
355 | * on simple regular filesystems. Anything that needs to change on-disk |
356 | * or wire state on size changes needs its own setattr method. |
357 | */ |
358 | int simple_setattr(struct dentry *dentry, struct iattr *iattr) |
359 | { |
360 | struct inode *inode = dentry->d_inode; |
361 | int error; |
362 | |
363 | WARN_ON_ONCE(inode->i_op->truncate); |
364 | |
365 | error = inode_change_ok(inode, iattr); |
366 | if (error) |
367 | return error; |
368 | |
369 | if (iattr->ia_valid & ATTR_SIZE) |
370 | truncate_setsize(inode, iattr->ia_size); |
371 | setattr_copy(inode, iattr); |
372 | mark_inode_dirty(inode); |
373 | return 0; |
374 | } |
375 | EXPORT_SYMBOL(simple_setattr); |
376 | |
377 | int simple_readpage(struct file *file, struct page *page) |
378 | { |
379 | clear_highpage(page); |
380 | flush_dcache_page(page); |
381 | SetPageUptodate(page); |
382 | unlock_page(page); |
383 | return 0; |
384 | } |
385 | |
386 | int simple_write_begin(struct file *file, struct address_space *mapping, |
387 | loff_t pos, unsigned len, unsigned flags, |
388 | struct page **pagep, void **fsdata) |
389 | { |
390 | struct page *page; |
391 | pgoff_t index; |
392 | |
393 | index = pos >> PAGE_CACHE_SHIFT; |
394 | |
395 | page = grab_cache_page_write_begin(mapping, index, flags); |
396 | if (!page) |
397 | return -ENOMEM; |
398 | |
399 | *pagep = page; |
400 | |
401 | if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { |
402 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
403 | |
404 | zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); |
405 | } |
406 | return 0; |
407 | } |
408 | |
409 | /** |
410 | * simple_write_end - .write_end helper for non-block-device FSes |
411 | * @available: See .write_end of address_space_operations |
412 | * @file: " |
413 | * @mapping: " |
414 | * @pos: " |
415 | * @len: " |
416 | * @copied: " |
417 | * @page: " |
418 | * @fsdata: " |
419 | * |
420 | * simple_write_end does the minimum needed for updating a page after writing is |
421 | * done. It has the same API signature as the .write_end of |
422 | * address_space_operations vector. So it can just be set onto .write_end for |
423 | * FSes that don't need any other processing. i_mutex is assumed to be held. |
424 | * Block based filesystems should use generic_write_end(). |
425 | * NOTE: Even though i_size might get updated by this function, mark_inode_dirty |
426 | * is not called, so a filesystem that actually does store data in .write_inode |
427 | * should extend on what's done here with a call to mark_inode_dirty() in the |
428 | * case that i_size has changed. |
429 | */ |
430 | int simple_write_end(struct file *file, struct address_space *mapping, |
431 | loff_t pos, unsigned len, unsigned copied, |
432 | struct page *page, void *fsdata) |
433 | { |
434 | struct inode *inode = page->mapping->host; |
435 | loff_t last_pos = pos + copied; |
436 | |
437 | /* zero the stale part of the page if we did a short copy */ |
438 | if (copied < len) { |
439 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
440 | |
441 | zero_user(page, from + copied, len - copied); |
442 | } |
443 | |
444 | if (!PageUptodate(page)) |
445 | SetPageUptodate(page); |
446 | /* |
447 | * No need to use i_size_read() here, the i_size |
448 | * cannot change under us because we hold the i_mutex. |
449 | */ |
450 | if (last_pos > inode->i_size) |
451 | i_size_write(inode, last_pos); |
452 | |
453 | set_page_dirty(page); |
454 | unlock_page(page); |
455 | page_cache_release(page); |
456 | |
457 | return copied; |
458 | } |
459 | |
460 | /* |
461 | * the inodes created here are not hashed. If you use iunique to generate |
462 | * unique inode values later for this filesystem, then you must take care |
463 | * to pass it an appropriate max_reserved value to avoid collisions. |
464 | */ |
465 | int simple_fill_super(struct super_block *s, unsigned long magic, |
466 | struct tree_descr *files) |
467 | { |
468 | struct inode *inode; |
469 | struct dentry *root; |
470 | struct dentry *dentry; |
471 | int i; |
472 | |
473 | s->s_blocksize = PAGE_CACHE_SIZE; |
474 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; |
475 | s->s_magic = magic; |
476 | s->s_op = &simple_super_operations; |
477 | s->s_time_gran = 1; |
478 | |
479 | inode = new_inode(s); |
480 | if (!inode) |
481 | return -ENOMEM; |
482 | /* |
483 | * because the root inode is 1, the files array must not contain an |
484 | * entry at index 1 |
485 | */ |
486 | inode->i_ino = 1; |
487 | inode->i_mode = S_IFDIR | 0755; |
488 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
489 | inode->i_op = &simple_dir_inode_operations; |
490 | inode->i_fop = &simple_dir_operations; |
491 | inode->i_nlink = 2; |
492 | root = d_alloc_root(inode); |
493 | if (!root) { |
494 | iput(inode); |
495 | return -ENOMEM; |
496 | } |
497 | for (i = 0; !files->name || files->name[0]; i++, files++) { |
498 | if (!files->name) |
499 | continue; |
500 | |
501 | /* warn if it tries to conflict with the root inode */ |
502 | if (unlikely(i == 1)) |
503 | printk(KERN_WARNING "%s: %s passed in a files array" |
504 | "with an index of 1!\n", __func__, |
505 | s->s_type->name); |
506 | |
507 | dentry = d_alloc_name(root, files->name); |
508 | if (!dentry) |
509 | goto out; |
510 | inode = new_inode(s); |
511 | if (!inode) |
512 | goto out; |
513 | inode->i_mode = S_IFREG | files->mode; |
514 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
515 | inode->i_fop = files->ops; |
516 | inode->i_ino = i; |
517 | d_add(dentry, inode); |
518 | } |
519 | s->s_root = root; |
520 | return 0; |
521 | out: |
522 | d_genocide(root); |
523 | dput(root); |
524 | return -ENOMEM; |
525 | } |
526 | |
527 | static DEFINE_SPINLOCK(pin_fs_lock); |
528 | |
529 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
530 | { |
531 | struct vfsmount *mnt = NULL; |
532 | spin_lock(&pin_fs_lock); |
533 | if (unlikely(!*mount)) { |
534 | spin_unlock(&pin_fs_lock); |
535 | mnt = vfs_kern_mount(type, 0, type->name, NULL); |
536 | if (IS_ERR(mnt)) |
537 | return PTR_ERR(mnt); |
538 | spin_lock(&pin_fs_lock); |
539 | if (!*mount) |
540 | *mount = mnt; |
541 | } |
542 | mntget(*mount); |
543 | ++*count; |
544 | spin_unlock(&pin_fs_lock); |
545 | mntput(mnt); |
546 | return 0; |
547 | } |
548 | |
549 | void simple_release_fs(struct vfsmount **mount, int *count) |
550 | { |
551 | struct vfsmount *mnt; |
552 | spin_lock(&pin_fs_lock); |
553 | mnt = *mount; |
554 | if (!--*count) |
555 | *mount = NULL; |
556 | spin_unlock(&pin_fs_lock); |
557 | mntput(mnt); |
558 | } |
559 | |
560 | /** |
561 | * simple_read_from_buffer - copy data from the buffer to user space |
562 | * @to: the user space buffer to read to |
563 | * @count: the maximum number of bytes to read |
564 | * @ppos: the current position in the buffer |
565 | * @from: the buffer to read from |
566 | * @available: the size of the buffer |
567 | * |
568 | * The simple_read_from_buffer() function reads up to @count bytes from the |
569 | * buffer @from at offset @ppos into the user space address starting at @to. |
570 | * |
571 | * On success, the number of bytes read is returned and the offset @ppos is |
572 | * advanced by this number, or negative value is returned on error. |
573 | **/ |
574 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
575 | const void *from, size_t available) |
576 | { |
577 | loff_t pos = *ppos; |
578 | size_t ret; |
579 | |
580 | if (pos < 0) |
581 | return -EINVAL; |
582 | if (pos >= available || !count) |
583 | return 0; |
584 | if (count > available - pos) |
585 | count = available - pos; |
586 | ret = copy_to_user(to, from + pos, count); |
587 | if (ret == count) |
588 | return -EFAULT; |
589 | count -= ret; |
590 | *ppos = pos + count; |
591 | return count; |
592 | } |
593 | |
594 | /** |
595 | * simple_write_to_buffer - copy data from user space to the buffer |
596 | * @to: the buffer to write to |
597 | * @available: the size of the buffer |
598 | * @ppos: the current position in the buffer |
599 | * @from: the user space buffer to read from |
600 | * @count: the maximum number of bytes to read |
601 | * |
602 | * The simple_write_to_buffer() function reads up to @count bytes from the user |
603 | * space address starting at @from into the buffer @to at offset @ppos. |
604 | * |
605 | * On success, the number of bytes written is returned and the offset @ppos is |
606 | * advanced by this number, or negative value is returned on error. |
607 | **/ |
608 | ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, |
609 | const void __user *from, size_t count) |
610 | { |
611 | loff_t pos = *ppos; |
612 | size_t res; |
613 | |
614 | if (pos < 0) |
615 | return -EINVAL; |
616 | if (pos >= available || !count) |
617 | return 0; |
618 | if (count > available - pos) |
619 | count = available - pos; |
620 | res = copy_from_user(to + pos, from, count); |
621 | if (res == count) |
622 | return -EFAULT; |
623 | count -= res; |
624 | *ppos = pos + count; |
625 | return count; |
626 | } |
627 | |
628 | /** |
629 | * memory_read_from_buffer - copy data from the buffer |
630 | * @to: the kernel space buffer to read to |
631 | * @count: the maximum number of bytes to read |
632 | * @ppos: the current position in the buffer |
633 | * @from: the buffer to read from |
634 | * @available: the size of the buffer |
635 | * |
636 | * The memory_read_from_buffer() function reads up to @count bytes from the |
637 | * buffer @from at offset @ppos into the kernel space address starting at @to. |
638 | * |
639 | * On success, the number of bytes read is returned and the offset @ppos is |
640 | * advanced by this number, or negative value is returned on error. |
641 | **/ |
642 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
643 | const void *from, size_t available) |
644 | { |
645 | loff_t pos = *ppos; |
646 | |
647 | if (pos < 0) |
648 | return -EINVAL; |
649 | if (pos >= available) |
650 | return 0; |
651 | if (count > available - pos) |
652 | count = available - pos; |
653 | memcpy(to, from + pos, count); |
654 | *ppos = pos + count; |
655 | |
656 | return count; |
657 | } |
658 | |
659 | /* |
660 | * Transaction based IO. |
661 | * The file expects a single write which triggers the transaction, and then |
662 | * possibly a read which collects the result - which is stored in a |
663 | * file-local buffer. |
664 | */ |
665 | |
666 | void simple_transaction_set(struct file *file, size_t n) |
667 | { |
668 | struct simple_transaction_argresp *ar = file->private_data; |
669 | |
670 | BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); |
671 | |
672 | /* |
673 | * The barrier ensures that ar->size will really remain zero until |
674 | * ar->data is ready for reading. |
675 | */ |
676 | smp_mb(); |
677 | ar->size = n; |
678 | } |
679 | |
680 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
681 | { |
682 | struct simple_transaction_argresp *ar; |
683 | static DEFINE_SPINLOCK(simple_transaction_lock); |
684 | |
685 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) |
686 | return ERR_PTR(-EFBIG); |
687 | |
688 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); |
689 | if (!ar) |
690 | return ERR_PTR(-ENOMEM); |
691 | |
692 | spin_lock(&simple_transaction_lock); |
693 | |
694 | /* only one write allowed per open */ |
695 | if (file->private_data) { |
696 | spin_unlock(&simple_transaction_lock); |
697 | free_page((unsigned long)ar); |
698 | return ERR_PTR(-EBUSY); |
699 | } |
700 | |
701 | file->private_data = ar; |
702 | |
703 | spin_unlock(&simple_transaction_lock); |
704 | |
705 | if (copy_from_user(ar->data, buf, size)) |
706 | return ERR_PTR(-EFAULT); |
707 | |
708 | return ar->data; |
709 | } |
710 | |
711 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) |
712 | { |
713 | struct simple_transaction_argresp *ar = file->private_data; |
714 | |
715 | if (!ar) |
716 | return 0; |
717 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); |
718 | } |
719 | |
720 | int simple_transaction_release(struct inode *inode, struct file *file) |
721 | { |
722 | free_page((unsigned long)file->private_data); |
723 | return 0; |
724 | } |
725 | |
726 | /* Simple attribute files */ |
727 | |
728 | struct simple_attr { |
729 | int (*get)(void *, u64 *); |
730 | int (*set)(void *, u64); |
731 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
732 | char set_buf[24]; |
733 | void *data; |
734 | const char *fmt; /* format for read operation */ |
735 | struct mutex mutex; /* protects access to these buffers */ |
736 | }; |
737 | |
738 | /* simple_attr_open is called by an actual attribute open file operation |
739 | * to set the attribute specific access operations. */ |
740 | int simple_attr_open(struct inode *inode, struct file *file, |
741 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
742 | const char *fmt) |
743 | { |
744 | struct simple_attr *attr; |
745 | |
746 | attr = kmalloc(sizeof(*attr), GFP_KERNEL); |
747 | if (!attr) |
748 | return -ENOMEM; |
749 | |
750 | attr->get = get; |
751 | attr->set = set; |
752 | attr->data = inode->i_private; |
753 | attr->fmt = fmt; |
754 | mutex_init(&attr->mutex); |
755 | |
756 | file->private_data = attr; |
757 | |
758 | return nonseekable_open(inode, file); |
759 | } |
760 | |
761 | int simple_attr_release(struct inode *inode, struct file *file) |
762 | { |
763 | kfree(file->private_data); |
764 | return 0; |
765 | } |
766 | |
767 | /* read from the buffer that is filled with the get function */ |
768 | ssize_t simple_attr_read(struct file *file, char __user *buf, |
769 | size_t len, loff_t *ppos) |
770 | { |
771 | struct simple_attr *attr; |
772 | size_t size; |
773 | ssize_t ret; |
774 | |
775 | attr = file->private_data; |
776 | |
777 | if (!attr->get) |
778 | return -EACCES; |
779 | |
780 | ret = mutex_lock_interruptible(&attr->mutex); |
781 | if (ret) |
782 | return ret; |
783 | |
784 | if (*ppos) { /* continued read */ |
785 | size = strlen(attr->get_buf); |
786 | } else { /* first read */ |
787 | u64 val; |
788 | ret = attr->get(attr->data, &val); |
789 | if (ret) |
790 | goto out; |
791 | |
792 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
793 | attr->fmt, (unsigned long long)val); |
794 | } |
795 | |
796 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); |
797 | out: |
798 | mutex_unlock(&attr->mutex); |
799 | return ret; |
800 | } |
801 | |
802 | /* interpret the buffer as a number to call the set function with */ |
803 | ssize_t simple_attr_write(struct file *file, const char __user *buf, |
804 | size_t len, loff_t *ppos) |
805 | { |
806 | struct simple_attr *attr; |
807 | u64 val; |
808 | size_t size; |
809 | ssize_t ret; |
810 | |
811 | attr = file->private_data; |
812 | if (!attr->set) |
813 | return -EACCES; |
814 | |
815 | ret = mutex_lock_interruptible(&attr->mutex); |
816 | if (ret) |
817 | return ret; |
818 | |
819 | ret = -EFAULT; |
820 | size = min(sizeof(attr->set_buf) - 1, len); |
821 | if (copy_from_user(attr->set_buf, buf, size)) |
822 | goto out; |
823 | |
824 | attr->set_buf[size] = '\0'; |
825 | val = simple_strtol(attr->set_buf, NULL, 0); |
826 | ret = attr->set(attr->data, val); |
827 | if (ret == 0) |
828 | ret = len; /* on success, claim we got the whole input */ |
829 | out: |
830 | mutex_unlock(&attr->mutex); |
831 | return ret; |
832 | } |
833 | |
834 | /** |
835 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation |
836 | * @sb: filesystem to do the file handle conversion on |
837 | * @fid: file handle to convert |
838 | * @fh_len: length of the file handle in bytes |
839 | * @fh_type: type of file handle |
840 | * @get_inode: filesystem callback to retrieve inode |
841 | * |
842 | * This function decodes @fid as long as it has one of the well-known |
843 | * Linux filehandle types and calls @get_inode on it to retrieve the |
844 | * inode for the object specified in the file handle. |
845 | */ |
846 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, |
847 | int fh_len, int fh_type, struct inode *(*get_inode) |
848 | (struct super_block *sb, u64 ino, u32 gen)) |
849 | { |
850 | struct inode *inode = NULL; |
851 | |
852 | if (fh_len < 2) |
853 | return NULL; |
854 | |
855 | switch (fh_type) { |
856 | case FILEID_INO32_GEN: |
857 | case FILEID_INO32_GEN_PARENT: |
858 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); |
859 | break; |
860 | } |
861 | |
862 | return d_obtain_alias(inode); |
863 | } |
864 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); |
865 | |
866 | /** |
867 | * generic_fh_to_dentry - generic helper for the fh_to_parent export operation |
868 | * @sb: filesystem to do the file handle conversion on |
869 | * @fid: file handle to convert |
870 | * @fh_len: length of the file handle in bytes |
871 | * @fh_type: type of file handle |
872 | * @get_inode: filesystem callback to retrieve inode |
873 | * |
874 | * This function decodes @fid as long as it has one of the well-known |
875 | * Linux filehandle types and calls @get_inode on it to retrieve the |
876 | * inode for the _parent_ object specified in the file handle if it |
877 | * is specified in the file handle, or NULL otherwise. |
878 | */ |
879 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, |
880 | int fh_len, int fh_type, struct inode *(*get_inode) |
881 | (struct super_block *sb, u64 ino, u32 gen)) |
882 | { |
883 | struct inode *inode = NULL; |
884 | |
885 | if (fh_len <= 2) |
886 | return NULL; |
887 | |
888 | switch (fh_type) { |
889 | case FILEID_INO32_GEN_PARENT: |
890 | inode = get_inode(sb, fid->i32.parent_ino, |
891 | (fh_len > 3 ? fid->i32.parent_gen : 0)); |
892 | break; |
893 | } |
894 | |
895 | return d_obtain_alias(inode); |
896 | } |
897 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); |
898 | |
899 | /** |
900 | * generic_file_fsync - generic fsync implementation for simple filesystems |
901 | * @file: file to synchronize |
902 | * @datasync: only synchronize essential metadata if true |
903 | * |
904 | * This is a generic implementation of the fsync method for simple |
905 | * filesystems which track all non-inode metadata in the buffers list |
906 | * hanging off the address_space structure. |
907 | */ |
908 | int generic_file_fsync(struct file *file, int datasync) |
909 | { |
910 | struct inode *inode = file->f_mapping->host; |
911 | int err; |
912 | int ret; |
913 | |
914 | ret = sync_mapping_buffers(inode->i_mapping); |
915 | if (!(inode->i_state & I_DIRTY)) |
916 | return ret; |
917 | if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) |
918 | return ret; |
919 | |
920 | err = sync_inode_metadata(inode, 1); |
921 | if (ret == 0) |
922 | ret = err; |
923 | return ret; |
924 | } |
925 | EXPORT_SYMBOL(generic_file_fsync); |
926 | |
927 | /** |
928 | * generic_check_addressable - Check addressability of file system |
929 | * @blocksize_bits: log of file system block size |
930 | * @num_blocks: number of blocks in file system |
931 | * |
932 | * Determine whether a file system with @num_blocks blocks (and a |
933 | * block size of 2**@blocksize_bits) is addressable by the sector_t |
934 | * and page cache of the system. Return 0 if so and -EFBIG otherwise. |
935 | */ |
936 | int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) |
937 | { |
938 | u64 last_fs_block = num_blocks - 1; |
939 | u64 last_fs_page = |
940 | last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); |
941 | |
942 | if (unlikely(num_blocks == 0)) |
943 | return 0; |
944 | |
945 | if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) |
946 | return -EINVAL; |
947 | |
948 | if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || |
949 | (last_fs_page > (pgoff_t)(~0ULL))) { |
950 | return -EFBIG; |
951 | } |
952 | return 0; |
953 | } |
954 | EXPORT_SYMBOL(generic_check_addressable); |
955 | |
956 | /* |
957 | * No-op implementation of ->fsync for in-memory filesystems. |
958 | */ |
959 | int noop_fsync(struct file *file, int datasync) |
960 | { |
961 | return 0; |
962 | } |
963 | |
964 | EXPORT_SYMBOL(dcache_dir_close); |
965 | EXPORT_SYMBOL(dcache_dir_lseek); |
966 | EXPORT_SYMBOL(dcache_dir_open); |
967 | EXPORT_SYMBOL(dcache_readdir); |
968 | EXPORT_SYMBOL(generic_read_dir); |
969 | EXPORT_SYMBOL(mount_pseudo); |
970 | EXPORT_SYMBOL(simple_write_begin); |
971 | EXPORT_SYMBOL(simple_write_end); |
972 | EXPORT_SYMBOL(simple_dir_inode_operations); |
973 | EXPORT_SYMBOL(simple_dir_operations); |
974 | EXPORT_SYMBOL(simple_empty); |
975 | EXPORT_SYMBOL(simple_fill_super); |
976 | EXPORT_SYMBOL(simple_getattr); |
977 | EXPORT_SYMBOL(simple_link); |
978 | EXPORT_SYMBOL(simple_lookup); |
979 | EXPORT_SYMBOL(simple_pin_fs); |
980 | EXPORT_SYMBOL(simple_readpage); |
981 | EXPORT_SYMBOL(simple_release_fs); |
982 | EXPORT_SYMBOL(simple_rename); |
983 | EXPORT_SYMBOL(simple_rmdir); |
984 | EXPORT_SYMBOL(simple_statfs); |
985 | EXPORT_SYMBOL(noop_fsync); |
986 | EXPORT_SYMBOL(simple_unlink); |
987 | EXPORT_SYMBOL(simple_read_from_buffer); |
988 | EXPORT_SYMBOL(simple_write_to_buffer); |
989 | EXPORT_SYMBOL(memory_read_from_buffer); |
990 | EXPORT_SYMBOL(simple_transaction_set); |
991 | EXPORT_SYMBOL(simple_transaction_get); |
992 | EXPORT_SYMBOL(simple_transaction_read); |
993 | EXPORT_SYMBOL(simple_transaction_release); |
994 | EXPORT_SYMBOL_GPL(simple_attr_open); |
995 | EXPORT_SYMBOL_GPL(simple_attr_release); |
996 | EXPORT_SYMBOL_GPL(simple_attr_read); |
997 | EXPORT_SYMBOL_GPL(simple_attr_write); |
998 |
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od-2011-09-18
v2.6.34-rc5
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