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1 | /* |
2 | * fs/libfs.c |
3 | * Library for filesystems writers. |
4 | */ |
5 | |
6 | #include <linux/export.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/namei.h> |
14 | #include <linux/exportfs.h> |
15 | #include <linux/writeback.h> |
16 | #include <linux/buffer_head.h> /* sync_mapping_buffers */ |
17 | |
18 | #include <asm/uaccess.h> |
19 | |
20 | #include "internal.h" |
21 | |
22 | static inline int simple_positive(struct dentry *dentry) |
23 | { |
24 | return dentry->d_inode && !d_unhashed(dentry); |
25 | } |
26 | |
27 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, |
28 | struct kstat *stat) |
29 | { |
30 | struct inode *inode = dentry->d_inode; |
31 | generic_fillattr(inode, stat); |
32 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); |
33 | return 0; |
34 | } |
35 | EXPORT_SYMBOL(simple_getattr); |
36 | |
37 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
38 | { |
39 | buf->f_type = dentry->d_sb->s_magic; |
40 | buf->f_bsize = PAGE_CACHE_SIZE; |
41 | buf->f_namelen = NAME_MAX; |
42 | return 0; |
43 | } |
44 | EXPORT_SYMBOL(simple_statfs); |
45 | |
46 | /* |
47 | * Retaining negative dentries for an in-memory filesystem just wastes |
48 | * memory and lookup time: arrange for them to be deleted immediately. |
49 | */ |
50 | int always_delete_dentry(const struct dentry *dentry) |
51 | { |
52 | return 1; |
53 | } |
54 | EXPORT_SYMBOL(always_delete_dentry); |
55 | |
56 | const struct dentry_operations simple_dentry_operations = { |
57 | .d_delete = always_delete_dentry, |
58 | }; |
59 | EXPORT_SYMBOL(simple_dentry_operations); |
60 | |
61 | /* |
62 | * Lookup the data. This is trivial - if the dentry didn't already |
63 | * exist, we know it is negative. Set d_op to delete negative dentries. |
64 | */ |
65 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
66 | { |
67 | if (dentry->d_name.len > NAME_MAX) |
68 | return ERR_PTR(-ENAMETOOLONG); |
69 | if (!dentry->d_sb->s_d_op) |
70 | d_set_d_op(dentry, &simple_dentry_operations); |
71 | d_add(dentry, NULL); |
72 | return NULL; |
73 | } |
74 | EXPORT_SYMBOL(simple_lookup); |
75 | |
76 | int dcache_dir_open(struct inode *inode, struct file *file) |
77 | { |
78 | static struct qstr cursor_name = QSTR_INIT(".", 1); |
79 | |
80 | file->private_data = d_alloc(file->f_path.dentry, &cursor_name); |
81 | |
82 | return file->private_data ? 0 : -ENOMEM; |
83 | } |
84 | EXPORT_SYMBOL(dcache_dir_open); |
85 | |
86 | int dcache_dir_close(struct inode *inode, struct file *file) |
87 | { |
88 | dput(file->private_data); |
89 | return 0; |
90 | } |
91 | EXPORT_SYMBOL(dcache_dir_close); |
92 | |
93 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) |
94 | { |
95 | struct dentry *dentry = file->f_path.dentry; |
96 | mutex_lock(&dentry->d_inode->i_mutex); |
97 | switch (whence) { |
98 | case 1: |
99 | offset += file->f_pos; |
100 | case 0: |
101 | if (offset >= 0) |
102 | break; |
103 | default: |
104 | mutex_unlock(&dentry->d_inode->i_mutex); |
105 | return -EINVAL; |
106 | } |
107 | if (offset != file->f_pos) { |
108 | file->f_pos = offset; |
109 | if (file->f_pos >= 2) { |
110 | struct list_head *p; |
111 | struct dentry *cursor = file->private_data; |
112 | loff_t n = file->f_pos - 2; |
113 | |
114 | spin_lock(&dentry->d_lock); |
115 | /* d_lock not required for cursor */ |
116 | list_del(&cursor->d_u.d_child); |
117 | p = dentry->d_subdirs.next; |
118 | while (n && p != &dentry->d_subdirs) { |
119 | struct dentry *next; |
120 | next = list_entry(p, struct dentry, d_u.d_child); |
121 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
122 | if (simple_positive(next)) |
123 | n--; |
124 | spin_unlock(&next->d_lock); |
125 | p = p->next; |
126 | } |
127 | list_add_tail(&cursor->d_u.d_child, p); |
128 | spin_unlock(&dentry->d_lock); |
129 | } |
130 | } |
131 | mutex_unlock(&dentry->d_inode->i_mutex); |
132 | return offset; |
133 | } |
134 | EXPORT_SYMBOL(dcache_dir_lseek); |
135 | |
136 | /* Relationship between i_mode and the DT_xxx types */ |
137 | static inline unsigned char dt_type(struct inode *inode) |
138 | { |
139 | return (inode->i_mode >> 12) & 15; |
140 | } |
141 | |
142 | /* |
143 | * Directory is locked and all positive dentries in it are safe, since |
144 | * for ramfs-type trees they can't go away without unlink() or rmdir(), |
145 | * both impossible due to the lock on directory. |
146 | */ |
147 | |
148 | int dcache_readdir(struct file *file, struct dir_context *ctx) |
149 | { |
150 | struct dentry *dentry = file->f_path.dentry; |
151 | struct dentry *cursor = file->private_data; |
152 | struct list_head *p, *q = &cursor->d_u.d_child; |
153 | |
154 | if (!dir_emit_dots(file, ctx)) |
155 | return 0; |
156 | spin_lock(&dentry->d_lock); |
157 | if (ctx->pos == 2) |
158 | list_move(q, &dentry->d_subdirs); |
159 | |
160 | for (p = q->next; p != &dentry->d_subdirs; p = p->next) { |
161 | struct dentry *next = list_entry(p, struct dentry, d_u.d_child); |
162 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
163 | if (!simple_positive(next)) { |
164 | spin_unlock(&next->d_lock); |
165 | continue; |
166 | } |
167 | |
168 | spin_unlock(&next->d_lock); |
169 | spin_unlock(&dentry->d_lock); |
170 | if (!dir_emit(ctx, next->d_name.name, next->d_name.len, |
171 | next->d_inode->i_ino, dt_type(next->d_inode))) |
172 | return 0; |
173 | spin_lock(&dentry->d_lock); |
174 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
175 | /* next is still alive */ |
176 | list_move(q, p); |
177 | spin_unlock(&next->d_lock); |
178 | p = q; |
179 | ctx->pos++; |
180 | } |
181 | spin_unlock(&dentry->d_lock); |
182 | return 0; |
183 | } |
184 | EXPORT_SYMBOL(dcache_readdir); |
185 | |
186 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) |
187 | { |
188 | return -EISDIR; |
189 | } |
190 | EXPORT_SYMBOL(generic_read_dir); |
191 | |
192 | const struct file_operations simple_dir_operations = { |
193 | .open = dcache_dir_open, |
194 | .release = dcache_dir_close, |
195 | .llseek = dcache_dir_lseek, |
196 | .read = generic_read_dir, |
197 | .iterate = dcache_readdir, |
198 | .fsync = noop_fsync, |
199 | }; |
200 | EXPORT_SYMBOL(simple_dir_operations); |
201 | |
202 | const struct inode_operations simple_dir_inode_operations = { |
203 | .lookup = simple_lookup, |
204 | }; |
205 | EXPORT_SYMBOL(simple_dir_inode_operations); |
206 | |
207 | static const struct super_operations simple_super_operations = { |
208 | .statfs = simple_statfs, |
209 | }; |
210 | |
211 | /* |
212 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that |
213 | * will never be mountable) |
214 | */ |
215 | struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name, |
216 | const struct super_operations *ops, |
217 | const struct dentry_operations *dops, unsigned long magic) |
218 | { |
219 | struct super_block *s; |
220 | struct dentry *dentry; |
221 | struct inode *root; |
222 | struct qstr d_name = QSTR_INIT(name, strlen(name)); |
223 | |
224 | s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL); |
225 | if (IS_ERR(s)) |
226 | return ERR_CAST(s); |
227 | |
228 | s->s_maxbytes = MAX_LFS_FILESIZE; |
229 | s->s_blocksize = PAGE_SIZE; |
230 | s->s_blocksize_bits = PAGE_SHIFT; |
231 | s->s_magic = magic; |
232 | s->s_op = ops ? ops : &simple_super_operations; |
233 | s->s_time_gran = 1; |
234 | root = new_inode(s); |
235 | if (!root) |
236 | goto Enomem; |
237 | /* |
238 | * since this is the first inode, make it number 1. New inodes created |
239 | * after this must take care not to collide with it (by passing |
240 | * max_reserved of 1 to iunique). |
241 | */ |
242 | root->i_ino = 1; |
243 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
244 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; |
245 | dentry = __d_alloc(s, &d_name); |
246 | if (!dentry) { |
247 | iput(root); |
248 | goto Enomem; |
249 | } |
250 | d_instantiate(dentry, root); |
251 | s->s_root = dentry; |
252 | s->s_d_op = dops; |
253 | s->s_flags |= MS_ACTIVE; |
254 | return dget(s->s_root); |
255 | |
256 | Enomem: |
257 | deactivate_locked_super(s); |
258 | return ERR_PTR(-ENOMEM); |
259 | } |
260 | EXPORT_SYMBOL(mount_pseudo); |
261 | |
262 | int simple_open(struct inode *inode, struct file *file) |
263 | { |
264 | if (inode->i_private) |
265 | file->private_data = inode->i_private; |
266 | return 0; |
267 | } |
268 | EXPORT_SYMBOL(simple_open); |
269 | |
270 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
271 | { |
272 | struct inode *inode = old_dentry->d_inode; |
273 | |
274 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
275 | inc_nlink(inode); |
276 | ihold(inode); |
277 | dget(dentry); |
278 | d_instantiate(dentry, inode); |
279 | return 0; |
280 | } |
281 | EXPORT_SYMBOL(simple_link); |
282 | |
283 | int simple_empty(struct dentry *dentry) |
284 | { |
285 | struct dentry *child; |
286 | int ret = 0; |
287 | |
288 | spin_lock(&dentry->d_lock); |
289 | list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) { |
290 | spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); |
291 | if (simple_positive(child)) { |
292 | spin_unlock(&child->d_lock); |
293 | goto out; |
294 | } |
295 | spin_unlock(&child->d_lock); |
296 | } |
297 | ret = 1; |
298 | out: |
299 | spin_unlock(&dentry->d_lock); |
300 | return ret; |
301 | } |
302 | EXPORT_SYMBOL(simple_empty); |
303 | |
304 | int simple_unlink(struct inode *dir, struct dentry *dentry) |
305 | { |
306 | struct inode *inode = dentry->d_inode; |
307 | |
308 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
309 | drop_nlink(inode); |
310 | dput(dentry); |
311 | return 0; |
312 | } |
313 | EXPORT_SYMBOL(simple_unlink); |
314 | |
315 | int simple_rmdir(struct inode *dir, struct dentry *dentry) |
316 | { |
317 | if (!simple_empty(dentry)) |
318 | return -ENOTEMPTY; |
319 | |
320 | drop_nlink(dentry->d_inode); |
321 | simple_unlink(dir, dentry); |
322 | drop_nlink(dir); |
323 | return 0; |
324 | } |
325 | EXPORT_SYMBOL(simple_rmdir); |
326 | |
327 | int simple_rename(struct inode *old_dir, struct dentry *old_dentry, |
328 | struct inode *new_dir, struct dentry *new_dentry) |
329 | { |
330 | struct inode *inode = old_dentry->d_inode; |
331 | int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); |
332 | |
333 | if (!simple_empty(new_dentry)) |
334 | return -ENOTEMPTY; |
335 | |
336 | if (new_dentry->d_inode) { |
337 | simple_unlink(new_dir, new_dentry); |
338 | if (they_are_dirs) { |
339 | drop_nlink(new_dentry->d_inode); |
340 | drop_nlink(old_dir); |
341 | } |
342 | } else if (they_are_dirs) { |
343 | drop_nlink(old_dir); |
344 | inc_nlink(new_dir); |
345 | } |
346 | |
347 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = |
348 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; |
349 | |
350 | return 0; |
351 | } |
352 | EXPORT_SYMBOL(simple_rename); |
353 | |
354 | /** |
355 | * simple_setattr - setattr for simple filesystem |
356 | * @dentry: dentry |
357 | * @iattr: iattr structure |
358 | * |
359 | * Returns 0 on success, -error on failure. |
360 | * |
361 | * simple_setattr is a simple ->setattr implementation without a proper |
362 | * implementation of size changes. |
363 | * |
364 | * It can either be used for in-memory filesystems or special files |
365 | * on simple regular filesystems. Anything that needs to change on-disk |
366 | * or wire state on size changes needs its own setattr method. |
367 | */ |
368 | int simple_setattr(struct dentry *dentry, struct iattr *iattr) |
369 | { |
370 | struct inode *inode = dentry->d_inode; |
371 | int error; |
372 | |
373 | error = inode_change_ok(inode, iattr); |
374 | if (error) |
375 | return error; |
376 | |
377 | if (iattr->ia_valid & ATTR_SIZE) |
378 | truncate_setsize(inode, iattr->ia_size); |
379 | setattr_copy(inode, iattr); |
380 | mark_inode_dirty(inode); |
381 | return 0; |
382 | } |
383 | EXPORT_SYMBOL(simple_setattr); |
384 | |
385 | int simple_readpage(struct file *file, struct page *page) |
386 | { |
387 | clear_highpage(page); |
388 | flush_dcache_page(page); |
389 | SetPageUptodate(page); |
390 | unlock_page(page); |
391 | return 0; |
392 | } |
393 | EXPORT_SYMBOL(simple_readpage); |
394 | |
395 | int simple_write_begin(struct file *file, struct address_space *mapping, |
396 | loff_t pos, unsigned len, unsigned flags, |
397 | struct page **pagep, void **fsdata) |
398 | { |
399 | struct page *page; |
400 | pgoff_t index; |
401 | |
402 | index = pos >> PAGE_CACHE_SHIFT; |
403 | |
404 | page = grab_cache_page_write_begin(mapping, index, flags); |
405 | if (!page) |
406 | return -ENOMEM; |
407 | |
408 | *pagep = page; |
409 | |
410 | if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { |
411 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
412 | |
413 | zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); |
414 | } |
415 | return 0; |
416 | } |
417 | EXPORT_SYMBOL(simple_write_begin); |
418 | |
419 | /** |
420 | * simple_write_end - .write_end helper for non-block-device FSes |
421 | * @available: See .write_end of address_space_operations |
422 | * @file: " |
423 | * @mapping: " |
424 | * @pos: " |
425 | * @len: " |
426 | * @copied: " |
427 | * @page: " |
428 | * @fsdata: " |
429 | * |
430 | * simple_write_end does the minimum needed for updating a page after writing is |
431 | * done. It has the same API signature as the .write_end of |
432 | * address_space_operations vector. So it can just be set onto .write_end for |
433 | * FSes that don't need any other processing. i_mutex is assumed to be held. |
434 | * Block based filesystems should use generic_write_end(). |
435 | * NOTE: Even though i_size might get updated by this function, mark_inode_dirty |
436 | * is not called, so a filesystem that actually does store data in .write_inode |
437 | * should extend on what's done here with a call to mark_inode_dirty() in the |
438 | * case that i_size has changed. |
439 | */ |
440 | int simple_write_end(struct file *file, struct address_space *mapping, |
441 | loff_t pos, unsigned len, unsigned copied, |
442 | struct page *page, void *fsdata) |
443 | { |
444 | struct inode *inode = page->mapping->host; |
445 | loff_t last_pos = pos + copied; |
446 | |
447 | /* zero the stale part of the page if we did a short copy */ |
448 | if (copied < len) { |
449 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
450 | |
451 | zero_user(page, from + copied, len - copied); |
452 | } |
453 | |
454 | if (!PageUptodate(page)) |
455 | SetPageUptodate(page); |
456 | /* |
457 | * No need to use i_size_read() here, the i_size |
458 | * cannot change under us because we hold the i_mutex. |
459 | */ |
460 | if (last_pos > inode->i_size) |
461 | i_size_write(inode, last_pos); |
462 | |
463 | set_page_dirty(page); |
464 | unlock_page(page); |
465 | page_cache_release(page); |
466 | |
467 | return copied; |
468 | } |
469 | EXPORT_SYMBOL(simple_write_end); |
470 | |
471 | /* |
472 | * the inodes created here are not hashed. If you use iunique to generate |
473 | * unique inode values later for this filesystem, then you must take care |
474 | * to pass it an appropriate max_reserved value to avoid collisions. |
475 | */ |
476 | int simple_fill_super(struct super_block *s, unsigned long magic, |
477 | struct tree_descr *files) |
478 | { |
479 | struct inode *inode; |
480 | struct dentry *root; |
481 | struct dentry *dentry; |
482 | int i; |
483 | |
484 | s->s_blocksize = PAGE_CACHE_SIZE; |
485 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; |
486 | s->s_magic = magic; |
487 | s->s_op = &simple_super_operations; |
488 | s->s_time_gran = 1; |
489 | |
490 | inode = new_inode(s); |
491 | if (!inode) |
492 | return -ENOMEM; |
493 | /* |
494 | * because the root inode is 1, the files array must not contain an |
495 | * entry at index 1 |
496 | */ |
497 | inode->i_ino = 1; |
498 | inode->i_mode = S_IFDIR | 0755; |
499 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
500 | inode->i_op = &simple_dir_inode_operations; |
501 | inode->i_fop = &simple_dir_operations; |
502 | set_nlink(inode, 2); |
503 | root = d_make_root(inode); |
504 | if (!root) |
505 | return -ENOMEM; |
506 | for (i = 0; !files->name || files->name[0]; i++, files++) { |
507 | if (!files->name) |
508 | continue; |
509 | |
510 | /* warn if it tries to conflict with the root inode */ |
511 | if (unlikely(i == 1)) |
512 | printk(KERN_WARNING "%s: %s passed in a files array" |
513 | "with an index of 1!\n", __func__, |
514 | s->s_type->name); |
515 | |
516 | dentry = d_alloc_name(root, files->name); |
517 | if (!dentry) |
518 | goto out; |
519 | inode = new_inode(s); |
520 | if (!inode) { |
521 | dput(dentry); |
522 | goto out; |
523 | } |
524 | inode->i_mode = S_IFREG | files->mode; |
525 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
526 | inode->i_fop = files->ops; |
527 | inode->i_ino = i; |
528 | d_add(dentry, inode); |
529 | } |
530 | s->s_root = root; |
531 | return 0; |
532 | out: |
533 | d_genocide(root); |
534 | shrink_dcache_parent(root); |
535 | dput(root); |
536 | return -ENOMEM; |
537 | } |
538 | EXPORT_SYMBOL(simple_fill_super); |
539 | |
540 | static DEFINE_SPINLOCK(pin_fs_lock); |
541 | |
542 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
543 | { |
544 | struct vfsmount *mnt = NULL; |
545 | spin_lock(&pin_fs_lock); |
546 | if (unlikely(!*mount)) { |
547 | spin_unlock(&pin_fs_lock); |
548 | mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL); |
549 | if (IS_ERR(mnt)) |
550 | return PTR_ERR(mnt); |
551 | spin_lock(&pin_fs_lock); |
552 | if (!*mount) |
553 | *mount = mnt; |
554 | } |
555 | mntget(*mount); |
556 | ++*count; |
557 | spin_unlock(&pin_fs_lock); |
558 | mntput(mnt); |
559 | return 0; |
560 | } |
561 | EXPORT_SYMBOL(simple_pin_fs); |
562 | |
563 | void simple_release_fs(struct vfsmount **mount, int *count) |
564 | { |
565 | struct vfsmount *mnt; |
566 | spin_lock(&pin_fs_lock); |
567 | mnt = *mount; |
568 | if (!--*count) |
569 | *mount = NULL; |
570 | spin_unlock(&pin_fs_lock); |
571 | mntput(mnt); |
572 | } |
573 | EXPORT_SYMBOL(simple_release_fs); |
574 | |
575 | /** |
576 | * simple_read_from_buffer - copy data from the buffer to user space |
577 | * @to: the user space buffer to read to |
578 | * @count: the maximum number of bytes to read |
579 | * @ppos: the current position in the buffer |
580 | * @from: the buffer to read from |
581 | * @available: the size of the buffer |
582 | * |
583 | * The simple_read_from_buffer() function reads up to @count bytes from the |
584 | * buffer @from at offset @ppos into the user space address starting at @to. |
585 | * |
586 | * On success, the number of bytes read is returned and the offset @ppos is |
587 | * advanced by this number, or negative value is returned on error. |
588 | **/ |
589 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
590 | const void *from, size_t available) |
591 | { |
592 | loff_t pos = *ppos; |
593 | size_t ret; |
594 | |
595 | if (pos < 0) |
596 | return -EINVAL; |
597 | if (pos >= available || !count) |
598 | return 0; |
599 | if (count > available - pos) |
600 | count = available - pos; |
601 | ret = copy_to_user(to, from + pos, count); |
602 | if (ret == count) |
603 | return -EFAULT; |
604 | count -= ret; |
605 | *ppos = pos + count; |
606 | return count; |
607 | } |
608 | EXPORT_SYMBOL(simple_read_from_buffer); |
609 | |
610 | /** |
611 | * simple_write_to_buffer - copy data from user space to the buffer |
612 | * @to: the buffer to write to |
613 | * @available: the size of the buffer |
614 | * @ppos: the current position in the buffer |
615 | * @from: the user space buffer to read from |
616 | * @count: the maximum number of bytes to read |
617 | * |
618 | * The simple_write_to_buffer() function reads up to @count bytes from the user |
619 | * space address starting at @from into the buffer @to at offset @ppos. |
620 | * |
621 | * On success, the number of bytes written is returned and the offset @ppos is |
622 | * advanced by this number, or negative value is returned on error. |
623 | **/ |
624 | ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, |
625 | const void __user *from, size_t count) |
626 | { |
627 | loff_t pos = *ppos; |
628 | size_t res; |
629 | |
630 | if (pos < 0) |
631 | return -EINVAL; |
632 | if (pos >= available || !count) |
633 | return 0; |
634 | if (count > available - pos) |
635 | count = available - pos; |
636 | res = copy_from_user(to + pos, from, count); |
637 | if (res == count) |
638 | return -EFAULT; |
639 | count -= res; |
640 | *ppos = pos + count; |
641 | return count; |
642 | } |
643 | EXPORT_SYMBOL(simple_write_to_buffer); |
644 | |
645 | /** |
646 | * memory_read_from_buffer - copy data from the buffer |
647 | * @to: the kernel space buffer to read to |
648 | * @count: the maximum number of bytes to read |
649 | * @ppos: the current position in the buffer |
650 | * @from: the buffer to read from |
651 | * @available: the size of the buffer |
652 | * |
653 | * The memory_read_from_buffer() function reads up to @count bytes from the |
654 | * buffer @from at offset @ppos into the kernel space address starting at @to. |
655 | * |
656 | * On success, the number of bytes read is returned and the offset @ppos is |
657 | * advanced by this number, or negative value is returned on error. |
658 | **/ |
659 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
660 | const void *from, size_t available) |
661 | { |
662 | loff_t pos = *ppos; |
663 | |
664 | if (pos < 0) |
665 | return -EINVAL; |
666 | if (pos >= available) |
667 | return 0; |
668 | if (count > available - pos) |
669 | count = available - pos; |
670 | memcpy(to, from + pos, count); |
671 | *ppos = pos + count; |
672 | |
673 | return count; |
674 | } |
675 | EXPORT_SYMBOL(memory_read_from_buffer); |
676 | |
677 | /* |
678 | * Transaction based IO. |
679 | * The file expects a single write which triggers the transaction, and then |
680 | * possibly a read which collects the result - which is stored in a |
681 | * file-local buffer. |
682 | */ |
683 | |
684 | void simple_transaction_set(struct file *file, size_t n) |
685 | { |
686 | struct simple_transaction_argresp *ar = file->private_data; |
687 | |
688 | BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); |
689 | |
690 | /* |
691 | * The barrier ensures that ar->size will really remain zero until |
692 | * ar->data is ready for reading. |
693 | */ |
694 | smp_mb(); |
695 | ar->size = n; |
696 | } |
697 | EXPORT_SYMBOL(simple_transaction_set); |
698 | |
699 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
700 | { |
701 | struct simple_transaction_argresp *ar; |
702 | static DEFINE_SPINLOCK(simple_transaction_lock); |
703 | |
704 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) |
705 | return ERR_PTR(-EFBIG); |
706 | |
707 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); |
708 | if (!ar) |
709 | return ERR_PTR(-ENOMEM); |
710 | |
711 | spin_lock(&simple_transaction_lock); |
712 | |
713 | /* only one write allowed per open */ |
714 | if (file->private_data) { |
715 | spin_unlock(&simple_transaction_lock); |
716 | free_page((unsigned long)ar); |
717 | return ERR_PTR(-EBUSY); |
718 | } |
719 | |
720 | file->private_data = ar; |
721 | |
722 | spin_unlock(&simple_transaction_lock); |
723 | |
724 | if (copy_from_user(ar->data, buf, size)) |
725 | return ERR_PTR(-EFAULT); |
726 | |
727 | return ar->data; |
728 | } |
729 | EXPORT_SYMBOL(simple_transaction_get); |
730 | |
731 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) |
732 | { |
733 | struct simple_transaction_argresp *ar = file->private_data; |
734 | |
735 | if (!ar) |
736 | return 0; |
737 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); |
738 | } |
739 | EXPORT_SYMBOL(simple_transaction_read); |
740 | |
741 | int simple_transaction_release(struct inode *inode, struct file *file) |
742 | { |
743 | free_page((unsigned long)file->private_data); |
744 | return 0; |
745 | } |
746 | EXPORT_SYMBOL(simple_transaction_release); |
747 | |
748 | /* Simple attribute files */ |
749 | |
750 | struct simple_attr { |
751 | int (*get)(void *, u64 *); |
752 | int (*set)(void *, u64); |
753 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
754 | char set_buf[24]; |
755 | void *data; |
756 | const char *fmt; /* format for read operation */ |
757 | struct mutex mutex; /* protects access to these buffers */ |
758 | }; |
759 | |
760 | /* simple_attr_open is called by an actual attribute open file operation |
761 | * to set the attribute specific access operations. */ |
762 | int simple_attr_open(struct inode *inode, struct file *file, |
763 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
764 | const char *fmt) |
765 | { |
766 | struct simple_attr *attr; |
767 | |
768 | attr = kmalloc(sizeof(*attr), GFP_KERNEL); |
769 | if (!attr) |
770 | return -ENOMEM; |
771 | |
772 | attr->get = get; |
773 | attr->set = set; |
774 | attr->data = inode->i_private; |
775 | attr->fmt = fmt; |
776 | mutex_init(&attr->mutex); |
777 | |
778 | file->private_data = attr; |
779 | |
780 | return nonseekable_open(inode, file); |
781 | } |
782 | EXPORT_SYMBOL_GPL(simple_attr_open); |
783 | |
784 | int simple_attr_release(struct inode *inode, struct file *file) |
785 | { |
786 | kfree(file->private_data); |
787 | return 0; |
788 | } |
789 | EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */ |
790 | |
791 | /* read from the buffer that is filled with the get function */ |
792 | ssize_t simple_attr_read(struct file *file, char __user *buf, |
793 | size_t len, loff_t *ppos) |
794 | { |
795 | struct simple_attr *attr; |
796 | size_t size; |
797 | ssize_t ret; |
798 | |
799 | attr = file->private_data; |
800 | |
801 | if (!attr->get) |
802 | return -EACCES; |
803 | |
804 | ret = mutex_lock_interruptible(&attr->mutex); |
805 | if (ret) |
806 | return ret; |
807 | |
808 | if (*ppos) { /* continued read */ |
809 | size = strlen(attr->get_buf); |
810 | } else { /* first read */ |
811 | u64 val; |
812 | ret = attr->get(attr->data, &val); |
813 | if (ret) |
814 | goto out; |
815 | |
816 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
817 | attr->fmt, (unsigned long long)val); |
818 | } |
819 | |
820 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); |
821 | out: |
822 | mutex_unlock(&attr->mutex); |
823 | return ret; |
824 | } |
825 | EXPORT_SYMBOL_GPL(simple_attr_read); |
826 | |
827 | /* interpret the buffer as a number to call the set function with */ |
828 | ssize_t simple_attr_write(struct file *file, const char __user *buf, |
829 | size_t len, loff_t *ppos) |
830 | { |
831 | struct simple_attr *attr; |
832 | u64 val; |
833 | size_t size; |
834 | ssize_t ret; |
835 | |
836 | attr = file->private_data; |
837 | if (!attr->set) |
838 | return -EACCES; |
839 | |
840 | ret = mutex_lock_interruptible(&attr->mutex); |
841 | if (ret) |
842 | return ret; |
843 | |
844 | ret = -EFAULT; |
845 | size = min(sizeof(attr->set_buf) - 1, len); |
846 | if (copy_from_user(attr->set_buf, buf, size)) |
847 | goto out; |
848 | |
849 | attr->set_buf[size] = '\0'; |
850 | val = simple_strtoll(attr->set_buf, NULL, 0); |
851 | ret = attr->set(attr->data, val); |
852 | if (ret == 0) |
853 | ret = len; /* on success, claim we got the whole input */ |
854 | out: |
855 | mutex_unlock(&attr->mutex); |
856 | return ret; |
857 | } |
858 | EXPORT_SYMBOL_GPL(simple_attr_write); |
859 | |
860 | /** |
861 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation |
862 | * @sb: filesystem to do the file handle conversion on |
863 | * @fid: file handle to convert |
864 | * @fh_len: length of the file handle in bytes |
865 | * @fh_type: type of file handle |
866 | * @get_inode: filesystem callback to retrieve inode |
867 | * |
868 | * This function decodes @fid as long as it has one of the well-known |
869 | * Linux filehandle types and calls @get_inode on it to retrieve the |
870 | * inode for the object specified in the file handle. |
871 | */ |
872 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, |
873 | int fh_len, int fh_type, struct inode *(*get_inode) |
874 | (struct super_block *sb, u64 ino, u32 gen)) |
875 | { |
876 | struct inode *inode = NULL; |
877 | |
878 | if (fh_len < 2) |
879 | return NULL; |
880 | |
881 | switch (fh_type) { |
882 | case FILEID_INO32_GEN: |
883 | case FILEID_INO32_GEN_PARENT: |
884 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); |
885 | break; |
886 | } |
887 | |
888 | return d_obtain_alias(inode); |
889 | } |
890 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); |
891 | |
892 | /** |
893 | * generic_fh_to_parent - generic helper for the fh_to_parent export operation |
894 | * @sb: filesystem to do the file handle conversion on |
895 | * @fid: file handle to convert |
896 | * @fh_len: length of the file handle in bytes |
897 | * @fh_type: type of file handle |
898 | * @get_inode: filesystem callback to retrieve inode |
899 | * |
900 | * This function decodes @fid as long as it has one of the well-known |
901 | * Linux filehandle types and calls @get_inode on it to retrieve the |
902 | * inode for the _parent_ object specified in the file handle if it |
903 | * is specified in the file handle, or NULL otherwise. |
904 | */ |
905 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, |
906 | int fh_len, int fh_type, struct inode *(*get_inode) |
907 | (struct super_block *sb, u64 ino, u32 gen)) |
908 | { |
909 | struct inode *inode = NULL; |
910 | |
911 | if (fh_len <= 2) |
912 | return NULL; |
913 | |
914 | switch (fh_type) { |
915 | case FILEID_INO32_GEN_PARENT: |
916 | inode = get_inode(sb, fid->i32.parent_ino, |
917 | (fh_len > 3 ? fid->i32.parent_gen : 0)); |
918 | break; |
919 | } |
920 | |
921 | return d_obtain_alias(inode); |
922 | } |
923 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); |
924 | |
925 | /** |
926 | * generic_file_fsync - generic fsync implementation for simple filesystems |
927 | * @file: file to synchronize |
928 | * @datasync: only synchronize essential metadata if true |
929 | * |
930 | * This is a generic implementation of the fsync method for simple |
931 | * filesystems which track all non-inode metadata in the buffers list |
932 | * hanging off the address_space structure. |
933 | */ |
934 | int generic_file_fsync(struct file *file, loff_t start, loff_t end, |
935 | int datasync) |
936 | { |
937 | struct inode *inode = file->f_mapping->host; |
938 | int err; |
939 | int ret; |
940 | |
941 | err = filemap_write_and_wait_range(inode->i_mapping, start, end); |
942 | if (err) |
943 | return err; |
944 | |
945 | mutex_lock(&inode->i_mutex); |
946 | ret = sync_mapping_buffers(inode->i_mapping); |
947 | if (!(inode->i_state & I_DIRTY)) |
948 | goto out; |
949 | if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) |
950 | goto out; |
951 | |
952 | err = sync_inode_metadata(inode, 1); |
953 | if (ret == 0) |
954 | ret = err; |
955 | out: |
956 | mutex_unlock(&inode->i_mutex); |
957 | return ret; |
958 | } |
959 | EXPORT_SYMBOL(generic_file_fsync); |
960 | |
961 | /** |
962 | * generic_check_addressable - Check addressability of file system |
963 | * @blocksize_bits: log of file system block size |
964 | * @num_blocks: number of blocks in file system |
965 | * |
966 | * Determine whether a file system with @num_blocks blocks (and a |
967 | * block size of 2**@blocksize_bits) is addressable by the sector_t |
968 | * and page cache of the system. Return 0 if so and -EFBIG otherwise. |
969 | */ |
970 | int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) |
971 | { |
972 | u64 last_fs_block = num_blocks - 1; |
973 | u64 last_fs_page = |
974 | last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); |
975 | |
976 | if (unlikely(num_blocks == 0)) |
977 | return 0; |
978 | |
979 | if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) |
980 | return -EINVAL; |
981 | |
982 | if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || |
983 | (last_fs_page > (pgoff_t)(~0ULL))) { |
984 | return -EFBIG; |
985 | } |
986 | return 0; |
987 | } |
988 | EXPORT_SYMBOL(generic_check_addressable); |
989 | |
990 | /* |
991 | * No-op implementation of ->fsync for in-memory filesystems. |
992 | */ |
993 | int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync) |
994 | { |
995 | return 0; |
996 | } |
997 | EXPORT_SYMBOL(noop_fsync); |
998 | |
999 | void kfree_put_link(struct dentry *dentry, struct nameidata *nd, |
1000 | void *cookie) |
1001 | { |
1002 | char *s = nd_get_link(nd); |
1003 | if (!IS_ERR(s)) |
1004 | kfree(s); |
1005 | } |
1006 | EXPORT_SYMBOL(kfree_put_link); |
1007 | |
1008 | /* |
1009 | * nop .set_page_dirty method so that people can use .page_mkwrite on |
1010 | * anon inodes. |
1011 | */ |
1012 | static int anon_set_page_dirty(struct page *page) |
1013 | { |
1014 | return 0; |
1015 | }; |
1016 | |
1017 | /* |
1018 | * A single inode exists for all anon_inode files. Contrary to pipes, |
1019 | * anon_inode inodes have no associated per-instance data, so we need |
1020 | * only allocate one of them. |
1021 | */ |
1022 | struct inode *alloc_anon_inode(struct super_block *s) |
1023 | { |
1024 | static const struct address_space_operations anon_aops = { |
1025 | .set_page_dirty = anon_set_page_dirty, |
1026 | }; |
1027 | struct inode *inode = new_inode_pseudo(s); |
1028 | |
1029 | if (!inode) |
1030 | return ERR_PTR(-ENOMEM); |
1031 | |
1032 | inode->i_ino = get_next_ino(); |
1033 | inode->i_mapping->a_ops = &anon_aops; |
1034 | |
1035 | /* |
1036 | * Mark the inode dirty from the very beginning, |
1037 | * that way it will never be moved to the dirty |
1038 | * list because mark_inode_dirty() will think |
1039 | * that it already _is_ on the dirty list. |
1040 | */ |
1041 | inode->i_state = I_DIRTY; |
1042 | inode->i_mode = S_IRUSR | S_IWUSR; |
1043 | inode->i_uid = current_fsuid(); |
1044 | inode->i_gid = current_fsgid(); |
1045 | inode->i_flags |= S_PRIVATE; |
1046 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
1047 | return inode; |
1048 | } |
1049 | EXPORT_SYMBOL(alloc_anon_inode); |
1050 |
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