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Source at commit b386be689295730688885552666ea40b2e639b14 created 11 years 11 months ago. By Maarten ter Huurne, Revert "MIPS: JZ4740: reset: Initialize hibernate wakeup counters." | |
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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> /* sync_mapping_buffers */ |
16 | |
17 | #include <asm/uaccess.h> |
18 | |
19 | #include "internal.h" |
20 | |
21 | static inline int simple_positive(struct dentry *dentry) |
22 | { |
23 | return dentry->d_inode && !d_unhashed(dentry); |
24 | } |
25 | |
26 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, |
27 | struct kstat *stat) |
28 | { |
29 | struct inode *inode = dentry->d_inode; |
30 | generic_fillattr(inode, stat); |
31 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); |
32 | return 0; |
33 | } |
34 | |
35 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
36 | { |
37 | buf->f_type = dentry->d_sb->s_magic; |
38 | buf->f_bsize = PAGE_CACHE_SIZE; |
39 | buf->f_namelen = NAME_MAX; |
40 | return 0; |
41 | } |
42 | |
43 | /* |
44 | * Retaining negative dentries for an in-memory filesystem just wastes |
45 | * memory and lookup time: arrange for them to be deleted immediately. |
46 | */ |
47 | static int simple_delete_dentry(const struct dentry *dentry) |
48 | { |
49 | return 1; |
50 | } |
51 | |
52 | /* |
53 | * Lookup the data. This is trivial - if the dentry didn't already |
54 | * exist, we know it is negative. Set d_op to delete negative dentries. |
55 | */ |
56 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) |
57 | { |
58 | static const struct dentry_operations simple_dentry_operations = { |
59 | .d_delete = simple_delete_dentry, |
60 | }; |
61 | |
62 | if (dentry->d_name.len > NAME_MAX) |
63 | return ERR_PTR(-ENAMETOOLONG); |
64 | d_set_d_op(dentry, &simple_dentry_operations); |
65 | d_add(dentry, NULL); |
66 | return NULL; |
67 | } |
68 | |
69 | int dcache_dir_open(struct inode *inode, struct file *file) |
70 | { |
71 | static struct qstr cursor_name = {.len = 1, .name = "."}; |
72 | |
73 | file->private_data = d_alloc(file->f_path.dentry, &cursor_name); |
74 | |
75 | return file->private_data ? 0 : -ENOMEM; |
76 | } |
77 | |
78 | int dcache_dir_close(struct inode *inode, struct file *file) |
79 | { |
80 | dput(file->private_data); |
81 | return 0; |
82 | } |
83 | |
84 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) |
85 | { |
86 | struct dentry *dentry = file->f_path.dentry; |
87 | mutex_lock(&dentry->d_inode->i_mutex); |
88 | switch (origin) { |
89 | case 1: |
90 | offset += file->f_pos; |
91 | case 0: |
92 | if (offset >= 0) |
93 | break; |
94 | default: |
95 | mutex_unlock(&dentry->d_inode->i_mutex); |
96 | return -EINVAL; |
97 | } |
98 | if (offset != file->f_pos) { |
99 | file->f_pos = offset; |
100 | if (file->f_pos >= 2) { |
101 | struct list_head *p; |
102 | struct dentry *cursor = file->private_data; |
103 | loff_t n = file->f_pos - 2; |
104 | |
105 | spin_lock(&dentry->d_lock); |
106 | /* d_lock not required for cursor */ |
107 | list_del(&cursor->d_u.d_child); |
108 | p = dentry->d_subdirs.next; |
109 | while (n && p != &dentry->d_subdirs) { |
110 | struct dentry *next; |
111 | next = list_entry(p, struct dentry, d_u.d_child); |
112 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
113 | if (simple_positive(next)) |
114 | n--; |
115 | spin_unlock(&next->d_lock); |
116 | p = p->next; |
117 | } |
118 | list_add_tail(&cursor->d_u.d_child, p); |
119 | spin_unlock(&dentry->d_lock); |
120 | } |
121 | } |
122 | mutex_unlock(&dentry->d_inode->i_mutex); |
123 | return offset; |
124 | } |
125 | |
126 | /* Relationship between i_mode and the DT_xxx types */ |
127 | static inline unsigned char dt_type(struct inode *inode) |
128 | { |
129 | return (inode->i_mode >> 12) & 15; |
130 | } |
131 | |
132 | /* |
133 | * Directory is locked and all positive dentries in it are safe, since |
134 | * for ramfs-type trees they can't go away without unlink() or rmdir(), |
135 | * both impossible due to the lock on directory. |
136 | */ |
137 | |
138 | int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) |
139 | { |
140 | struct dentry *dentry = filp->f_path.dentry; |
141 | struct dentry *cursor = filp->private_data; |
142 | struct list_head *p, *q = &cursor->d_u.d_child; |
143 | ino_t ino; |
144 | int i = filp->f_pos; |
145 | |
146 | switch (i) { |
147 | case 0: |
148 | ino = dentry->d_inode->i_ino; |
149 | if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) |
150 | break; |
151 | filp->f_pos++; |
152 | i++; |
153 | /* fallthrough */ |
154 | case 1: |
155 | ino = parent_ino(dentry); |
156 | if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) |
157 | break; |
158 | filp->f_pos++; |
159 | i++; |
160 | /* fallthrough */ |
161 | default: |
162 | spin_lock(&dentry->d_lock); |
163 | if (filp->f_pos == 2) |
164 | list_move(q, &dentry->d_subdirs); |
165 | |
166 | for (p=q->next; p != &dentry->d_subdirs; p=p->next) { |
167 | struct dentry *next; |
168 | next = list_entry(p, struct dentry, d_u.d_child); |
169 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
170 | if (!simple_positive(next)) { |
171 | spin_unlock(&next->d_lock); |
172 | continue; |
173 | } |
174 | |
175 | spin_unlock(&next->d_lock); |
176 | spin_unlock(&dentry->d_lock); |
177 | if (filldir(dirent, next->d_name.name, |
178 | next->d_name.len, filp->f_pos, |
179 | next->d_inode->i_ino, |
180 | dt_type(next->d_inode)) < 0) |
181 | return 0; |
182 | spin_lock(&dentry->d_lock); |
183 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
184 | /* next is still alive */ |
185 | list_move(q, p); |
186 | spin_unlock(&next->d_lock); |
187 | p = q; |
188 | filp->f_pos++; |
189 | } |
190 | spin_unlock(&dentry->d_lock); |
191 | } |
192 | return 0; |
193 | } |
194 | |
195 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) |
196 | { |
197 | return -EISDIR; |
198 | } |
199 | |
200 | const struct file_operations simple_dir_operations = { |
201 | .open = dcache_dir_open, |
202 | .release = dcache_dir_close, |
203 | .llseek = dcache_dir_lseek, |
204 | .read = generic_read_dir, |
205 | .readdir = dcache_readdir, |
206 | .fsync = noop_fsync, |
207 | }; |
208 | |
209 | const struct inode_operations simple_dir_inode_operations = { |
210 | .lookup = simple_lookup, |
211 | }; |
212 | |
213 | static const struct super_operations simple_super_operations = { |
214 | .statfs = simple_statfs, |
215 | }; |
216 | |
217 | /* |
218 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that |
219 | * will never be mountable) |
220 | */ |
221 | struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name, |
222 | const struct super_operations *ops, |
223 | const struct dentry_operations *dops, unsigned long magic) |
224 | { |
225 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); |
226 | struct dentry *dentry; |
227 | struct inode *root; |
228 | struct qstr d_name = {.name = name, .len = strlen(name)}; |
229 | |
230 | if (IS_ERR(s)) |
231 | return ERR_CAST(s); |
232 | |
233 | s->s_flags = MS_NOUSER; |
234 | s->s_maxbytes = MAX_LFS_FILESIZE; |
235 | s->s_blocksize = PAGE_SIZE; |
236 | s->s_blocksize_bits = PAGE_SHIFT; |
237 | s->s_magic = magic; |
238 | s->s_op = ops ? ops : &simple_super_operations; |
239 | s->s_time_gran = 1; |
240 | root = new_inode(s); |
241 | if (!root) |
242 | goto Enomem; |
243 | /* |
244 | * since this is the first inode, make it number 1. New inodes created |
245 | * after this must take care not to collide with it (by passing |
246 | * max_reserved of 1 to iunique). |
247 | */ |
248 | root->i_ino = 1; |
249 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
250 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; |
251 | dentry = __d_alloc(s, &d_name); |
252 | if (!dentry) { |
253 | iput(root); |
254 | goto Enomem; |
255 | } |
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(new_dentry->d_inode); |
333 | drop_nlink(old_dir); |
334 | } |
335 | } else if (they_are_dirs) { |
336 | drop_nlink(old_dir); |
337 | inc_nlink(new_dir); |
338 | } |
339 | |
340 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = |
341 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; |
342 | |
343 | return 0; |
344 | } |
345 | |
346 | /** |
347 | * simple_setattr - setattr for simple filesystem |
348 | * @dentry: dentry |
349 | * @iattr: iattr structure |
350 | * |
351 | * Returns 0 on success, -error on failure. |
352 | * |
353 | * simple_setattr is a simple ->setattr implementation without a proper |
354 | * implementation of size changes. |
355 | * |
356 | * It can either be used for in-memory filesystems or special files |
357 | * on simple regular filesystems. Anything that needs to change on-disk |
358 | * or wire state on size changes needs its own setattr method. |
359 | */ |
360 | int simple_setattr(struct dentry *dentry, struct iattr *iattr) |
361 | { |
362 | struct inode *inode = dentry->d_inode; |
363 | int error; |
364 | |
365 | WARN_ON_ONCE(inode->i_op->truncate); |
366 | |
367 | error = inode_change_ok(inode, iattr); |
368 | if (error) |
369 | return error; |
370 | |
371 | if (iattr->ia_valid & ATTR_SIZE) |
372 | truncate_setsize(inode, iattr->ia_size); |
373 | setattr_copy(inode, iattr); |
374 | mark_inode_dirty(inode); |
375 | return 0; |
376 | } |
377 | EXPORT_SYMBOL(simple_setattr); |
378 | |
379 | int simple_readpage(struct file *file, struct page *page) |
380 | { |
381 | clear_highpage(page); |
382 | flush_dcache_page(page); |
383 | SetPageUptodate(page); |
384 | unlock_page(page); |
385 | return 0; |
386 | } |
387 | |
388 | int simple_write_begin(struct file *file, struct address_space *mapping, |
389 | loff_t pos, unsigned len, unsigned flags, |
390 | struct page **pagep, void **fsdata) |
391 | { |
392 | struct page *page; |
393 | pgoff_t index; |
394 | |
395 | index = pos >> PAGE_CACHE_SHIFT; |
396 | |
397 | page = grab_cache_page_write_begin(mapping, index, flags); |
398 | if (!page) |
399 | return -ENOMEM; |
400 | |
401 | *pagep = page; |
402 | |
403 | if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { |
404 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
405 | |
406 | zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); |
407 | } |
408 | return 0; |
409 | } |
410 | |
411 | /** |
412 | * simple_write_end - .write_end helper for non-block-device FSes |
413 | * @available: See .write_end of address_space_operations |
414 | * @file: " |
415 | * @mapping: " |
416 | * @pos: " |
417 | * @len: " |
418 | * @copied: " |
419 | * @page: " |
420 | * @fsdata: " |
421 | * |
422 | * simple_write_end does the minimum needed for updating a page after writing is |
423 | * done. It has the same API signature as the .write_end of |
424 | * address_space_operations vector. So it can just be set onto .write_end for |
425 | * FSes that don't need any other processing. i_mutex is assumed to be held. |
426 | * Block based filesystems should use generic_write_end(). |
427 | * NOTE: Even though i_size might get updated by this function, mark_inode_dirty |
428 | * is not called, so a filesystem that actually does store data in .write_inode |
429 | * should extend on what's done here with a call to mark_inode_dirty() in the |
430 | * case that i_size has changed. |
431 | */ |
432 | int simple_write_end(struct file *file, struct address_space *mapping, |
433 | loff_t pos, unsigned len, unsigned copied, |
434 | struct page *page, void *fsdata) |
435 | { |
436 | struct inode *inode = page->mapping->host; |
437 | loff_t last_pos = pos + copied; |
438 | |
439 | /* zero the stale part of the page if we did a short copy */ |
440 | if (copied < len) { |
441 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
442 | |
443 | zero_user(page, from + copied, len - copied); |
444 | } |
445 | |
446 | if (!PageUptodate(page)) |
447 | SetPageUptodate(page); |
448 | /* |
449 | * No need to use i_size_read() here, the i_size |
450 | * cannot change under us because we hold the i_mutex. |
451 | */ |
452 | if (last_pos > inode->i_size) |
453 | i_size_write(inode, last_pos); |
454 | |
455 | set_page_dirty(page); |
456 | unlock_page(page); |
457 | page_cache_release(page); |
458 | |
459 | return copied; |
460 | } |
461 | |
462 | /* |
463 | * the inodes created here are not hashed. If you use iunique to generate |
464 | * unique inode values later for this filesystem, then you must take care |
465 | * to pass it an appropriate max_reserved value to avoid collisions. |
466 | */ |
467 | int simple_fill_super(struct super_block *s, unsigned long magic, |
468 | struct tree_descr *files) |
469 | { |
470 | struct inode *inode; |
471 | struct dentry *root; |
472 | struct dentry *dentry; |
473 | int i; |
474 | |
475 | s->s_blocksize = PAGE_CACHE_SIZE; |
476 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; |
477 | s->s_magic = magic; |
478 | s->s_op = &simple_super_operations; |
479 | s->s_time_gran = 1; |
480 | |
481 | inode = new_inode(s); |
482 | if (!inode) |
483 | return -ENOMEM; |
484 | /* |
485 | * because the root inode is 1, the files array must not contain an |
486 | * entry at index 1 |
487 | */ |
488 | inode->i_ino = 1; |
489 | inode->i_mode = S_IFDIR | 0755; |
490 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
491 | inode->i_op = &simple_dir_inode_operations; |
492 | inode->i_fop = &simple_dir_operations; |
493 | set_nlink(inode, 2); |
494 | root = d_alloc_root(inode); |
495 | if (!root) { |
496 | iput(inode); |
497 | return -ENOMEM; |
498 | } |
499 | for (i = 0; !files->name || files->name[0]; i++, files++) { |
500 | if (!files->name) |
501 | continue; |
502 | |
503 | /* warn if it tries to conflict with the root inode */ |
504 | if (unlikely(i == 1)) |
505 | printk(KERN_WARNING "%s: %s passed in a files array" |
506 | "with an index of 1!\n", __func__, |
507 | s->s_type->name); |
508 | |
509 | dentry = d_alloc_name(root, files->name); |
510 | if (!dentry) |
511 | goto out; |
512 | inode = new_inode(s); |
513 | if (!inode) { |
514 | dput(dentry); |
515 | goto out; |
516 | } |
517 | inode->i_mode = S_IFREG | files->mode; |
518 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
519 | inode->i_fop = files->ops; |
520 | inode->i_ino = i; |
521 | d_add(dentry, inode); |
522 | } |
523 | s->s_root = root; |
524 | return 0; |
525 | out: |
526 | d_genocide(root); |
527 | dput(root); |
528 | return -ENOMEM; |
529 | } |
530 | |
531 | static DEFINE_SPINLOCK(pin_fs_lock); |
532 | |
533 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
534 | { |
535 | struct vfsmount *mnt = NULL; |
536 | spin_lock(&pin_fs_lock); |
537 | if (unlikely(!*mount)) { |
538 | spin_unlock(&pin_fs_lock); |
539 | mnt = vfs_kern_mount(type, 0, type->name, NULL); |
540 | if (IS_ERR(mnt)) |
541 | return PTR_ERR(mnt); |
542 | spin_lock(&pin_fs_lock); |
543 | if (!*mount) |
544 | *mount = mnt; |
545 | } |
546 | mntget(*mount); |
547 | ++*count; |
548 | spin_unlock(&pin_fs_lock); |
549 | mntput(mnt); |
550 | return 0; |
551 | } |
552 | |
553 | void simple_release_fs(struct vfsmount **mount, int *count) |
554 | { |
555 | struct vfsmount *mnt; |
556 | spin_lock(&pin_fs_lock); |
557 | mnt = *mount; |
558 | if (!--*count) |
559 | *mount = NULL; |
560 | spin_unlock(&pin_fs_lock); |
561 | mntput(mnt); |
562 | } |
563 | |
564 | /** |
565 | * simple_read_from_buffer - copy data from the buffer to user space |
566 | * @to: the user space buffer to read to |
567 | * @count: the maximum number of bytes to read |
568 | * @ppos: the current position in the buffer |
569 | * @from: the buffer to read from |
570 | * @available: the size of the buffer |
571 | * |
572 | * The simple_read_from_buffer() function reads up to @count bytes from the |
573 | * buffer @from at offset @ppos into the user space address starting at @to. |
574 | * |
575 | * On success, the number of bytes read is returned and the offset @ppos is |
576 | * advanced by this number, or negative value is returned on error. |
577 | **/ |
578 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
579 | const void *from, size_t available) |
580 | { |
581 | loff_t pos = *ppos; |
582 | size_t ret; |
583 | |
584 | if (pos < 0) |
585 | return -EINVAL; |
586 | if (pos >= available || !count) |
587 | return 0; |
588 | if (count > available - pos) |
589 | count = available - pos; |
590 | ret = copy_to_user(to, from + pos, count); |
591 | if (ret == count) |
592 | return -EFAULT; |
593 | count -= ret; |
594 | *ppos = pos + count; |
595 | return count; |
596 | } |
597 | |
598 | /** |
599 | * simple_write_to_buffer - copy data from user space to the buffer |
600 | * @to: the buffer to write to |
601 | * @available: the size of the buffer |
602 | * @ppos: the current position in the buffer |
603 | * @from: the user space buffer to read from |
604 | * @count: the maximum number of bytes to read |
605 | * |
606 | * The simple_write_to_buffer() function reads up to @count bytes from the user |
607 | * space address starting at @from into the buffer @to at offset @ppos. |
608 | * |
609 | * On success, the number of bytes written is returned and the offset @ppos is |
610 | * advanced by this number, or negative value is returned on error. |
611 | **/ |
612 | ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, |
613 | const void __user *from, size_t count) |
614 | { |
615 | loff_t pos = *ppos; |
616 | size_t res; |
617 | |
618 | if (pos < 0) |
619 | return -EINVAL; |
620 | if (pos >= available || !count) |
621 | return 0; |
622 | if (count > available - pos) |
623 | count = available - pos; |
624 | res = copy_from_user(to + pos, from, count); |
625 | if (res == count) |
626 | return -EFAULT; |
627 | count -= res; |
628 | *ppos = pos + count; |
629 | return count; |
630 | } |
631 | |
632 | /** |
633 | * memory_read_from_buffer - copy data from the buffer |
634 | * @to: the kernel space buffer to read to |
635 | * @count: the maximum number of bytes to read |
636 | * @ppos: the current position in the buffer |
637 | * @from: the buffer to read from |
638 | * @available: the size of the buffer |
639 | * |
640 | * The memory_read_from_buffer() function reads up to @count bytes from the |
641 | * buffer @from at offset @ppos into the kernel space address starting at @to. |
642 | * |
643 | * On success, the number of bytes read is returned and the offset @ppos is |
644 | * advanced by this number, or negative value is returned on error. |
645 | **/ |
646 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
647 | const void *from, size_t available) |
648 | { |
649 | loff_t pos = *ppos; |
650 | |
651 | if (pos < 0) |
652 | return -EINVAL; |
653 | if (pos >= available) |
654 | return 0; |
655 | if (count > available - pos) |
656 | count = available - pos; |
657 | memcpy(to, from + pos, count); |
658 | *ppos = pos + count; |
659 | |
660 | return count; |
661 | } |
662 | |
663 | /* |
664 | * Transaction based IO. |
665 | * The file expects a single write which triggers the transaction, and then |
666 | * possibly a read which collects the result - which is stored in a |
667 | * file-local buffer. |
668 | */ |
669 | |
670 | void simple_transaction_set(struct file *file, size_t n) |
671 | { |
672 | struct simple_transaction_argresp *ar = file->private_data; |
673 | |
674 | BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); |
675 | |
676 | /* |
677 | * The barrier ensures that ar->size will really remain zero until |
678 | * ar->data is ready for reading. |
679 | */ |
680 | smp_mb(); |
681 | ar->size = n; |
682 | } |
683 | |
684 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
685 | { |
686 | struct simple_transaction_argresp *ar; |
687 | static DEFINE_SPINLOCK(simple_transaction_lock); |
688 | |
689 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) |
690 | return ERR_PTR(-EFBIG); |
691 | |
692 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); |
693 | if (!ar) |
694 | return ERR_PTR(-ENOMEM); |
695 | |
696 | spin_lock(&simple_transaction_lock); |
697 | |
698 | /* only one write allowed per open */ |
699 | if (file->private_data) { |
700 | spin_unlock(&simple_transaction_lock); |
701 | free_page((unsigned long)ar); |
702 | return ERR_PTR(-EBUSY); |
703 | } |
704 | |
705 | file->private_data = ar; |
706 | |
707 | spin_unlock(&simple_transaction_lock); |
708 | |
709 | if (copy_from_user(ar->data, buf, size)) |
710 | return ERR_PTR(-EFAULT); |
711 | |
712 | return ar->data; |
713 | } |
714 | |
715 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) |
716 | { |
717 | struct simple_transaction_argresp *ar = file->private_data; |
718 | |
719 | if (!ar) |
720 | return 0; |
721 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); |
722 | } |
723 | |
724 | int simple_transaction_release(struct inode *inode, struct file *file) |
725 | { |
726 | free_page((unsigned long)file->private_data); |
727 | return 0; |
728 | } |
729 | |
730 | /* Simple attribute files */ |
731 | |
732 | struct simple_attr { |
733 | int (*get)(void *, u64 *); |
734 | int (*set)(void *, u64); |
735 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
736 | char set_buf[24]; |
737 | void *data; |
738 | const char *fmt; /* format for read operation */ |
739 | struct mutex mutex; /* protects access to these buffers */ |
740 | }; |
741 | |
742 | /* simple_attr_open is called by an actual attribute open file operation |
743 | * to set the attribute specific access operations. */ |
744 | int simple_attr_open(struct inode *inode, struct file *file, |
745 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
746 | const char *fmt) |
747 | { |
748 | struct simple_attr *attr; |
749 | |
750 | attr = kmalloc(sizeof(*attr), GFP_KERNEL); |
751 | if (!attr) |
752 | return -ENOMEM; |
753 | |
754 | attr->get = get; |
755 | attr->set = set; |
756 | attr->data = inode->i_private; |
757 | attr->fmt = fmt; |
758 | mutex_init(&attr->mutex); |
759 | |
760 | file->private_data = attr; |
761 | |
762 | return nonseekable_open(inode, file); |
763 | } |
764 | |
765 | int simple_attr_release(struct inode *inode, struct file *file) |
766 | { |
767 | kfree(file->private_data); |
768 | return 0; |
769 | } |
770 | |
771 | /* read from the buffer that is filled with the get function */ |
772 | ssize_t simple_attr_read(struct file *file, char __user *buf, |
773 | size_t len, loff_t *ppos) |
774 | { |
775 | struct simple_attr *attr; |
776 | size_t size; |
777 | ssize_t ret; |
778 | |
779 | attr = file->private_data; |
780 | |
781 | if (!attr->get) |
782 | return -EACCES; |
783 | |
784 | ret = mutex_lock_interruptible(&attr->mutex); |
785 | if (ret) |
786 | return ret; |
787 | |
788 | if (*ppos) { /* continued read */ |
789 | size = strlen(attr->get_buf); |
790 | } else { /* first read */ |
791 | u64 val; |
792 | ret = attr->get(attr->data, &val); |
793 | if (ret) |
794 | goto out; |
795 | |
796 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
797 | attr->fmt, (unsigned long long)val); |
798 | } |
799 | |
800 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); |
801 | out: |
802 | mutex_unlock(&attr->mutex); |
803 | return ret; |
804 | } |
805 | |
806 | /* interpret the buffer as a number to call the set function with */ |
807 | ssize_t simple_attr_write(struct file *file, const char __user *buf, |
808 | size_t len, loff_t *ppos) |
809 | { |
810 | struct simple_attr *attr; |
811 | u64 val; |
812 | size_t size; |
813 | ssize_t ret; |
814 | |
815 | attr = file->private_data; |
816 | if (!attr->set) |
817 | return -EACCES; |
818 | |
819 | ret = mutex_lock_interruptible(&attr->mutex); |
820 | if (ret) |
821 | return ret; |
822 | |
823 | ret = -EFAULT; |
824 | size = min(sizeof(attr->set_buf) - 1, len); |
825 | if (copy_from_user(attr->set_buf, buf, size)) |
826 | goto out; |
827 | |
828 | attr->set_buf[size] = '\0'; |
829 | val = simple_strtoll(attr->set_buf, NULL, 0); |
830 | ret = attr->set(attr->data, val); |
831 | if (ret == 0) |
832 | ret = len; /* on success, claim we got the whole input */ |
833 | out: |
834 | mutex_unlock(&attr->mutex); |
835 | return ret; |
836 | } |
837 | |
838 | /** |
839 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation |
840 | * @sb: filesystem to do the file handle conversion on |
841 | * @fid: file handle to convert |
842 | * @fh_len: length of the file handle in bytes |
843 | * @fh_type: type of file handle |
844 | * @get_inode: filesystem callback to retrieve inode |
845 | * |
846 | * This function decodes @fid as long as it has one of the well-known |
847 | * Linux filehandle types and calls @get_inode on it to retrieve the |
848 | * inode for the object specified in the file handle. |
849 | */ |
850 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, |
851 | int fh_len, int fh_type, struct inode *(*get_inode) |
852 | (struct super_block *sb, u64 ino, u32 gen)) |
853 | { |
854 | struct inode *inode = NULL; |
855 | |
856 | if (fh_len < 2) |
857 | return NULL; |
858 | |
859 | switch (fh_type) { |
860 | case FILEID_INO32_GEN: |
861 | case FILEID_INO32_GEN_PARENT: |
862 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); |
863 | break; |
864 | } |
865 | |
866 | return d_obtain_alias(inode); |
867 | } |
868 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); |
869 | |
870 | /** |
871 | * generic_fh_to_dentry - generic helper for the fh_to_parent export operation |
872 | * @sb: filesystem to do the file handle conversion on |
873 | * @fid: file handle to convert |
874 | * @fh_len: length of the file handle in bytes |
875 | * @fh_type: type of file handle |
876 | * @get_inode: filesystem callback to retrieve inode |
877 | * |
878 | * This function decodes @fid as long as it has one of the well-known |
879 | * Linux filehandle types and calls @get_inode on it to retrieve the |
880 | * inode for the _parent_ object specified in the file handle if it |
881 | * is specified in the file handle, or NULL otherwise. |
882 | */ |
883 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, |
884 | int fh_len, int fh_type, struct inode *(*get_inode) |
885 | (struct super_block *sb, u64 ino, u32 gen)) |
886 | { |
887 | struct inode *inode = NULL; |
888 | |
889 | if (fh_len <= 2) |
890 | return NULL; |
891 | |
892 | switch (fh_type) { |
893 | case FILEID_INO32_GEN_PARENT: |
894 | inode = get_inode(sb, fid->i32.parent_ino, |
895 | (fh_len > 3 ? fid->i32.parent_gen : 0)); |
896 | break; |
897 | } |
898 | |
899 | return d_obtain_alias(inode); |
900 | } |
901 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); |
902 | |
903 | /** |
904 | * generic_file_fsync - generic fsync implementation for simple filesystems |
905 | * @file: file to synchronize |
906 | * @datasync: only synchronize essential metadata if true |
907 | * |
908 | * This is a generic implementation of the fsync method for simple |
909 | * filesystems which track all non-inode metadata in the buffers list |
910 | * hanging off the address_space structure. |
911 | */ |
912 | int generic_file_fsync(struct file *file, loff_t start, loff_t end, |
913 | int datasync) |
914 | { |
915 | struct inode *inode = file->f_mapping->host; |
916 | int err; |
917 | int ret; |
918 | |
919 | err = filemap_write_and_wait_range(inode->i_mapping, start, end); |
920 | if (err) |
921 | return err; |
922 | |
923 | mutex_lock(&inode->i_mutex); |
924 | ret = sync_mapping_buffers(inode->i_mapping); |
925 | if (!(inode->i_state & I_DIRTY)) |
926 | goto out; |
927 | if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) |
928 | goto out; |
929 | |
930 | err = sync_inode_metadata(inode, 1); |
931 | if (ret == 0) |
932 | ret = err; |
933 | out: |
934 | mutex_unlock(&inode->i_mutex); |
935 | return ret; |
936 | } |
937 | EXPORT_SYMBOL(generic_file_fsync); |
938 | |
939 | /** |
940 | * generic_check_addressable - Check addressability of file system |
941 | * @blocksize_bits: log of file system block size |
942 | * @num_blocks: number of blocks in file system |
943 | * |
944 | * Determine whether a file system with @num_blocks blocks (and a |
945 | * block size of 2**@blocksize_bits) is addressable by the sector_t |
946 | * and page cache of the system. Return 0 if so and -EFBIG otherwise. |
947 | */ |
948 | int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) |
949 | { |
950 | u64 last_fs_block = num_blocks - 1; |
951 | u64 last_fs_page = |
952 | last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); |
953 | |
954 | if (unlikely(num_blocks == 0)) |
955 | return 0; |
956 | |
957 | if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) |
958 | return -EINVAL; |
959 | |
960 | if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || |
961 | (last_fs_page > (pgoff_t)(~0ULL))) { |
962 | return -EFBIG; |
963 | } |
964 | return 0; |
965 | } |
966 | EXPORT_SYMBOL(generic_check_addressable); |
967 | |
968 | /* |
969 | * No-op implementation of ->fsync for in-memory filesystems. |
970 | */ |
971 | int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync) |
972 | { |
973 | return 0; |
974 | } |
975 | |
976 | EXPORT_SYMBOL(dcache_dir_close); |
977 | EXPORT_SYMBOL(dcache_dir_lseek); |
978 | EXPORT_SYMBOL(dcache_dir_open); |
979 | EXPORT_SYMBOL(dcache_readdir); |
980 | EXPORT_SYMBOL(generic_read_dir); |
981 | EXPORT_SYMBOL(mount_pseudo); |
982 | EXPORT_SYMBOL(simple_write_begin); |
983 | EXPORT_SYMBOL(simple_write_end); |
984 | EXPORT_SYMBOL(simple_dir_inode_operations); |
985 | EXPORT_SYMBOL(simple_dir_operations); |
986 | EXPORT_SYMBOL(simple_empty); |
987 | EXPORT_SYMBOL(simple_fill_super); |
988 | EXPORT_SYMBOL(simple_getattr); |
989 | EXPORT_SYMBOL(simple_link); |
990 | EXPORT_SYMBOL(simple_lookup); |
991 | EXPORT_SYMBOL(simple_pin_fs); |
992 | EXPORT_SYMBOL(simple_readpage); |
993 | EXPORT_SYMBOL(simple_release_fs); |
994 | EXPORT_SYMBOL(simple_rename); |
995 | EXPORT_SYMBOL(simple_rmdir); |
996 | EXPORT_SYMBOL(simple_statfs); |
997 | EXPORT_SYMBOL(noop_fsync); |
998 | EXPORT_SYMBOL(simple_unlink); |
999 | EXPORT_SYMBOL(simple_read_from_buffer); |
1000 | EXPORT_SYMBOL(simple_write_to_buffer); |
1001 | EXPORT_SYMBOL(memory_read_from_buffer); |
1002 | EXPORT_SYMBOL(simple_transaction_set); |
1003 | EXPORT_SYMBOL(simple_transaction_get); |
1004 | EXPORT_SYMBOL(simple_transaction_read); |
1005 | EXPORT_SYMBOL(simple_transaction_release); |
1006 | EXPORT_SYMBOL_GPL(simple_attr_open); |
1007 | EXPORT_SYMBOL_GPL(simple_attr_release); |
1008 | EXPORT_SYMBOL_GPL(simple_attr_read); |
1009 | EXPORT_SYMBOL_GPL(simple_attr_write); |
1010 |
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v2.6.34-rc5
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