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Source at commit fbf123cd4cc0c097fe9a99c90109ebb2a5e94a50 created 10 years 3 months ago. By Lars-Peter Clausen, dma: jz4740: Dequeue descriptor from active list before completing it | |
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1 | /* |
2 | * fs/libfs.c |
3 | * Library for filesystems writers. |
4 | */ |
5 | |
6 | #include <linux/blkdev.h> |
7 | #include <linux/export.h> |
8 | #include <linux/pagemap.h> |
9 | #include <linux/slab.h> |
10 | #include <linux/mount.h> |
11 | #include <linux/vfs.h> |
12 | #include <linux/quotaops.h> |
13 | #include <linux/mutex.h> |
14 | #include <linux/namei.h> |
15 | #include <linux/exportfs.h> |
16 | #include <linux/writeback.h> |
17 | #include <linux/buffer_head.h> /* sync_mapping_buffers */ |
18 | |
19 | #include <asm/uaccess.h> |
20 | |
21 | #include "internal.h" |
22 | |
23 | static inline int simple_positive(struct dentry *dentry) |
24 | { |
25 | return dentry->d_inode && !d_unhashed(dentry); |
26 | } |
27 | |
28 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, |
29 | struct kstat *stat) |
30 | { |
31 | struct inode *inode = dentry->d_inode; |
32 | generic_fillattr(inode, stat); |
33 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); |
34 | return 0; |
35 | } |
36 | EXPORT_SYMBOL(simple_getattr); |
37 | |
38 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
39 | { |
40 | buf->f_type = dentry->d_sb->s_magic; |
41 | buf->f_bsize = PAGE_CACHE_SIZE; |
42 | buf->f_namelen = NAME_MAX; |
43 | return 0; |
44 | } |
45 | EXPORT_SYMBOL(simple_statfs); |
46 | |
47 | /* |
48 | * Retaining negative dentries for an in-memory filesystem just wastes |
49 | * memory and lookup time: arrange for them to be deleted immediately. |
50 | */ |
51 | int always_delete_dentry(const struct dentry *dentry) |
52 | { |
53 | return 1; |
54 | } |
55 | EXPORT_SYMBOL(always_delete_dentry); |
56 | |
57 | const struct dentry_operations simple_dentry_operations = { |
58 | .d_delete = always_delete_dentry, |
59 | }; |
60 | EXPORT_SYMBOL(simple_dentry_operations); |
61 | |
62 | /* |
63 | * Lookup the data. This is trivial - if the dentry didn't already |
64 | * exist, we know it is negative. Set d_op to delete negative dentries. |
65 | */ |
66 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
67 | { |
68 | if (dentry->d_name.len > NAME_MAX) |
69 | return ERR_PTR(-ENAMETOOLONG); |
70 | if (!dentry->d_sb->s_d_op) |
71 | d_set_d_op(dentry, &simple_dentry_operations); |
72 | d_add(dentry, NULL); |
73 | return NULL; |
74 | } |
75 | EXPORT_SYMBOL(simple_lookup); |
76 | |
77 | int dcache_dir_open(struct inode *inode, struct file *file) |
78 | { |
79 | static struct qstr cursor_name = QSTR_INIT(".", 1); |
80 | |
81 | file->private_data = d_alloc(file->f_path.dentry, &cursor_name); |
82 | |
83 | return file->private_data ? 0 : -ENOMEM; |
84 | } |
85 | EXPORT_SYMBOL(dcache_dir_open); |
86 | |
87 | int dcache_dir_close(struct inode *inode, struct file *file) |
88 | { |
89 | dput(file->private_data); |
90 | return 0; |
91 | } |
92 | EXPORT_SYMBOL(dcache_dir_close); |
93 | |
94 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) |
95 | { |
96 | struct dentry *dentry = file->f_path.dentry; |
97 | mutex_lock(&dentry->d_inode->i_mutex); |
98 | switch (whence) { |
99 | case 1: |
100 | offset += file->f_pos; |
101 | case 0: |
102 | if (offset >= 0) |
103 | break; |
104 | default: |
105 | mutex_unlock(&dentry->d_inode->i_mutex); |
106 | return -EINVAL; |
107 | } |
108 | if (offset != file->f_pos) { |
109 | file->f_pos = offset; |
110 | if (file->f_pos >= 2) { |
111 | struct list_head *p; |
112 | struct dentry *cursor = file->private_data; |
113 | loff_t n = file->f_pos - 2; |
114 | |
115 | spin_lock(&dentry->d_lock); |
116 | /* d_lock not required for cursor */ |
117 | list_del(&cursor->d_u.d_child); |
118 | p = dentry->d_subdirs.next; |
119 | while (n && p != &dentry->d_subdirs) { |
120 | struct dentry *next; |
121 | next = list_entry(p, struct dentry, d_u.d_child); |
122 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
123 | if (simple_positive(next)) |
124 | n--; |
125 | spin_unlock(&next->d_lock); |
126 | p = p->next; |
127 | } |
128 | list_add_tail(&cursor->d_u.d_child, p); |
129 | spin_unlock(&dentry->d_lock); |
130 | } |
131 | } |
132 | mutex_unlock(&dentry->d_inode->i_mutex); |
133 | return offset; |
134 | } |
135 | EXPORT_SYMBOL(dcache_dir_lseek); |
136 | |
137 | /* Relationship between i_mode and the DT_xxx types */ |
138 | static inline unsigned char dt_type(struct inode *inode) |
139 | { |
140 | return (inode->i_mode >> 12) & 15; |
141 | } |
142 | |
143 | /* |
144 | * Directory is locked and all positive dentries in it are safe, since |
145 | * for ramfs-type trees they can't go away without unlink() or rmdir(), |
146 | * both impossible due to the lock on directory. |
147 | */ |
148 | |
149 | int dcache_readdir(struct file *file, struct dir_context *ctx) |
150 | { |
151 | struct dentry *dentry = file->f_path.dentry; |
152 | struct dentry *cursor = file->private_data; |
153 | struct list_head *p, *q = &cursor->d_u.d_child; |
154 | |
155 | if (!dir_emit_dots(file, ctx)) |
156 | return 0; |
157 | spin_lock(&dentry->d_lock); |
158 | if (ctx->pos == 2) |
159 | list_move(q, &dentry->d_subdirs); |
160 | |
161 | for (p = q->next; p != &dentry->d_subdirs; p = p->next) { |
162 | struct dentry *next = list_entry(p, struct dentry, d_u.d_child); |
163 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
164 | if (!simple_positive(next)) { |
165 | spin_unlock(&next->d_lock); |
166 | continue; |
167 | } |
168 | |
169 | spin_unlock(&next->d_lock); |
170 | spin_unlock(&dentry->d_lock); |
171 | if (!dir_emit(ctx, next->d_name.name, next->d_name.len, |
172 | next->d_inode->i_ino, dt_type(next->d_inode))) |
173 | return 0; |
174 | spin_lock(&dentry->d_lock); |
175 | spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); |
176 | /* next is still alive */ |
177 | list_move(q, p); |
178 | spin_unlock(&next->d_lock); |
179 | p = q; |
180 | ctx->pos++; |
181 | } |
182 | spin_unlock(&dentry->d_lock); |
183 | return 0; |
184 | } |
185 | EXPORT_SYMBOL(dcache_readdir); |
186 | |
187 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) |
188 | { |
189 | return -EISDIR; |
190 | } |
191 | EXPORT_SYMBOL(generic_read_dir); |
192 | |
193 | const struct file_operations simple_dir_operations = { |
194 | .open = dcache_dir_open, |
195 | .release = dcache_dir_close, |
196 | .llseek = dcache_dir_lseek, |
197 | .read = generic_read_dir, |
198 | .iterate = dcache_readdir, |
199 | .fsync = noop_fsync, |
200 | }; |
201 | EXPORT_SYMBOL(simple_dir_operations); |
202 | |
203 | const struct inode_operations simple_dir_inode_operations = { |
204 | .lookup = simple_lookup, |
205 | }; |
206 | EXPORT_SYMBOL(simple_dir_inode_operations); |
207 | |
208 | static const struct super_operations simple_super_operations = { |
209 | .statfs = simple_statfs, |
210 | }; |
211 | |
212 | /* |
213 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that |
214 | * will never be mountable) |
215 | */ |
216 | struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name, |
217 | const struct super_operations *ops, |
218 | const struct dentry_operations *dops, unsigned long magic) |
219 | { |
220 | struct super_block *s; |
221 | struct dentry *dentry; |
222 | struct inode *root; |
223 | struct qstr d_name = QSTR_INIT(name, strlen(name)); |
224 | |
225 | s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL); |
226 | if (IS_ERR(s)) |
227 | return ERR_CAST(s); |
228 | |
229 | s->s_maxbytes = MAX_LFS_FILESIZE; |
230 | s->s_blocksize = PAGE_SIZE; |
231 | s->s_blocksize_bits = PAGE_SHIFT; |
232 | s->s_magic = magic; |
233 | s->s_op = ops ? ops : &simple_super_operations; |
234 | s->s_time_gran = 1; |
235 | root = new_inode(s); |
236 | if (!root) |
237 | goto Enomem; |
238 | /* |
239 | * since this is the first inode, make it number 1. New inodes created |
240 | * after this must take care not to collide with it (by passing |
241 | * max_reserved of 1 to iunique). |
242 | */ |
243 | root->i_ino = 1; |
244 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
245 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; |
246 | dentry = __d_alloc(s, &d_name); |
247 | if (!dentry) { |
248 | iput(root); |
249 | goto Enomem; |
250 | } |
251 | d_instantiate(dentry, root); |
252 | s->s_root = dentry; |
253 | s->s_d_op = dops; |
254 | s->s_flags |= MS_ACTIVE; |
255 | return dget(s->s_root); |
256 | |
257 | Enomem: |
258 | deactivate_locked_super(s); |
259 | return ERR_PTR(-ENOMEM); |
260 | } |
261 | EXPORT_SYMBOL(mount_pseudo); |
262 | |
263 | int simple_open(struct inode *inode, struct file *file) |
264 | { |
265 | if (inode->i_private) |
266 | file->private_data = inode->i_private; |
267 | return 0; |
268 | } |
269 | EXPORT_SYMBOL(simple_open); |
270 | |
271 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
272 | { |
273 | struct inode *inode = old_dentry->d_inode; |
274 | |
275 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
276 | inc_nlink(inode); |
277 | ihold(inode); |
278 | dget(dentry); |
279 | d_instantiate(dentry, inode); |
280 | return 0; |
281 | } |
282 | EXPORT_SYMBOL(simple_link); |
283 | |
284 | int simple_empty(struct dentry *dentry) |
285 | { |
286 | struct dentry *child; |
287 | int ret = 0; |
288 | |
289 | spin_lock(&dentry->d_lock); |
290 | list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) { |
291 | spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); |
292 | if (simple_positive(child)) { |
293 | spin_unlock(&child->d_lock); |
294 | goto out; |
295 | } |
296 | spin_unlock(&child->d_lock); |
297 | } |
298 | ret = 1; |
299 | out: |
300 | spin_unlock(&dentry->d_lock); |
301 | return ret; |
302 | } |
303 | EXPORT_SYMBOL(simple_empty); |
304 | |
305 | int simple_unlink(struct inode *dir, struct dentry *dentry) |
306 | { |
307 | struct inode *inode = dentry->d_inode; |
308 | |
309 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
310 | drop_nlink(inode); |
311 | dput(dentry); |
312 | return 0; |
313 | } |
314 | EXPORT_SYMBOL(simple_unlink); |
315 | |
316 | int simple_rmdir(struct inode *dir, struct dentry *dentry) |
317 | { |
318 | if (!simple_empty(dentry)) |
319 | return -ENOTEMPTY; |
320 | |
321 | drop_nlink(dentry->d_inode); |
322 | simple_unlink(dir, dentry); |
323 | drop_nlink(dir); |
324 | return 0; |
325 | } |
326 | EXPORT_SYMBOL(simple_rmdir); |
327 | |
328 | int simple_rename(struct inode *old_dir, struct dentry *old_dentry, |
329 | struct inode *new_dir, struct dentry *new_dentry) |
330 | { |
331 | struct inode *inode = old_dentry->d_inode; |
332 | int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); |
333 | |
334 | if (!simple_empty(new_dentry)) |
335 | return -ENOTEMPTY; |
336 | |
337 | if (new_dentry->d_inode) { |
338 | simple_unlink(new_dir, new_dentry); |
339 | if (they_are_dirs) { |
340 | drop_nlink(new_dentry->d_inode); |
341 | drop_nlink(old_dir); |
342 | } |
343 | } else if (they_are_dirs) { |
344 | drop_nlink(old_dir); |
345 | inc_nlink(new_dir); |
346 | } |
347 | |
348 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = |
349 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; |
350 | |
351 | return 0; |
352 | } |
353 | EXPORT_SYMBOL(simple_rename); |
354 | |
355 | /** |
356 | * simple_setattr - setattr for simple filesystem |
357 | * @dentry: dentry |
358 | * @iattr: iattr structure |
359 | * |
360 | * Returns 0 on success, -error on failure. |
361 | * |
362 | * simple_setattr is a simple ->setattr implementation without a proper |
363 | * implementation of size changes. |
364 | * |
365 | * It can either be used for in-memory filesystems or special files |
366 | * on simple regular filesystems. Anything that needs to change on-disk |
367 | * or wire state on size changes needs its own setattr method. |
368 | */ |
369 | int simple_setattr(struct dentry *dentry, struct iattr *iattr) |
370 | { |
371 | struct inode *inode = dentry->d_inode; |
372 | int error; |
373 | |
374 | error = inode_change_ok(inode, iattr); |
375 | if (error) |
376 | return error; |
377 | |
378 | if (iattr->ia_valid & ATTR_SIZE) |
379 | truncate_setsize(inode, iattr->ia_size); |
380 | setattr_copy(inode, iattr); |
381 | mark_inode_dirty(inode); |
382 | return 0; |
383 | } |
384 | EXPORT_SYMBOL(simple_setattr); |
385 | |
386 | int simple_readpage(struct file *file, struct page *page) |
387 | { |
388 | clear_highpage(page); |
389 | flush_dcache_page(page); |
390 | SetPageUptodate(page); |
391 | unlock_page(page); |
392 | return 0; |
393 | } |
394 | EXPORT_SYMBOL(simple_readpage); |
395 | |
396 | int simple_write_begin(struct file *file, struct address_space *mapping, |
397 | loff_t pos, unsigned len, unsigned flags, |
398 | struct page **pagep, void **fsdata) |
399 | { |
400 | struct page *page; |
401 | pgoff_t index; |
402 | |
403 | index = pos >> PAGE_CACHE_SHIFT; |
404 | |
405 | page = grab_cache_page_write_begin(mapping, index, flags); |
406 | if (!page) |
407 | return -ENOMEM; |
408 | |
409 | *pagep = page; |
410 | |
411 | if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { |
412 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
413 | |
414 | zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); |
415 | } |
416 | return 0; |
417 | } |
418 | EXPORT_SYMBOL(simple_write_begin); |
419 | |
420 | /** |
421 | * simple_write_end - .write_end helper for non-block-device FSes |
422 | * @available: See .write_end of address_space_operations |
423 | * @file: " |
424 | * @mapping: " |
425 | * @pos: " |
426 | * @len: " |
427 | * @copied: " |
428 | * @page: " |
429 | * @fsdata: " |
430 | * |
431 | * simple_write_end does the minimum needed for updating a page after writing is |
432 | * done. It has the same API signature as the .write_end of |
433 | * address_space_operations vector. So it can just be set onto .write_end for |
434 | * FSes that don't need any other processing. i_mutex is assumed to be held. |
435 | * Block based filesystems should use generic_write_end(). |
436 | * NOTE: Even though i_size might get updated by this function, mark_inode_dirty |
437 | * is not called, so a filesystem that actually does store data in .write_inode |
438 | * should extend on what's done here with a call to mark_inode_dirty() in the |
439 | * case that i_size has changed. |
440 | */ |
441 | int simple_write_end(struct file *file, struct address_space *mapping, |
442 | loff_t pos, unsigned len, unsigned copied, |
443 | struct page *page, void *fsdata) |
444 | { |
445 | struct inode *inode = page->mapping->host; |
446 | loff_t last_pos = pos + copied; |
447 | |
448 | /* zero the stale part of the page if we did a short copy */ |
449 | if (copied < len) { |
450 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
451 | |
452 | zero_user(page, from + copied, len - copied); |
453 | } |
454 | |
455 | if (!PageUptodate(page)) |
456 | SetPageUptodate(page); |
457 | /* |
458 | * No need to use i_size_read() here, the i_size |
459 | * cannot change under us because we hold the i_mutex. |
460 | */ |
461 | if (last_pos > inode->i_size) |
462 | i_size_write(inode, last_pos); |
463 | |
464 | set_page_dirty(page); |
465 | unlock_page(page); |
466 | page_cache_release(page); |
467 | |
468 | return copied; |
469 | } |
470 | EXPORT_SYMBOL(simple_write_end); |
471 | |
472 | /* |
473 | * the inodes created here are not hashed. If you use iunique to generate |
474 | * unique inode values later for this filesystem, then you must take care |
475 | * to pass it an appropriate max_reserved value to avoid collisions. |
476 | */ |
477 | int simple_fill_super(struct super_block *s, unsigned long magic, |
478 | struct tree_descr *files) |
479 | { |
480 | struct inode *inode; |
481 | struct dentry *root; |
482 | struct dentry *dentry; |
483 | int i; |
484 | |
485 | s->s_blocksize = PAGE_CACHE_SIZE; |
486 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; |
487 | s->s_magic = magic; |
488 | s->s_op = &simple_super_operations; |
489 | s->s_time_gran = 1; |
490 | |
491 | inode = new_inode(s); |
492 | if (!inode) |
493 | return -ENOMEM; |
494 | /* |
495 | * because the root inode is 1, the files array must not contain an |
496 | * entry at index 1 |
497 | */ |
498 | inode->i_ino = 1; |
499 | inode->i_mode = S_IFDIR | 0755; |
500 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
501 | inode->i_op = &simple_dir_inode_operations; |
502 | inode->i_fop = &simple_dir_operations; |
503 | set_nlink(inode, 2); |
504 | root = d_make_root(inode); |
505 | if (!root) |
506 | return -ENOMEM; |
507 | for (i = 0; !files->name || files->name[0]; i++, files++) { |
508 | if (!files->name) |
509 | continue; |
510 | |
511 | /* warn if it tries to conflict with the root inode */ |
512 | if (unlikely(i == 1)) |
513 | printk(KERN_WARNING "%s: %s passed in a files array" |
514 | "with an index of 1!\n", __func__, |
515 | s->s_type->name); |
516 | |
517 | dentry = d_alloc_name(root, files->name); |
518 | if (!dentry) |
519 | goto out; |
520 | inode = new_inode(s); |
521 | if (!inode) { |
522 | dput(dentry); |
523 | goto out; |
524 | } |
525 | inode->i_mode = S_IFREG | files->mode; |
526 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
527 | inode->i_fop = files->ops; |
528 | inode->i_ino = i; |
529 | d_add(dentry, inode); |
530 | } |
531 | s->s_root = root; |
532 | return 0; |
533 | out: |
534 | d_genocide(root); |
535 | shrink_dcache_parent(root); |
536 | dput(root); |
537 | return -ENOMEM; |
538 | } |
539 | EXPORT_SYMBOL(simple_fill_super); |
540 | |
541 | static DEFINE_SPINLOCK(pin_fs_lock); |
542 | |
543 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
544 | { |
545 | struct vfsmount *mnt = NULL; |
546 | spin_lock(&pin_fs_lock); |
547 | if (unlikely(!*mount)) { |
548 | spin_unlock(&pin_fs_lock); |
549 | mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL); |
550 | if (IS_ERR(mnt)) |
551 | return PTR_ERR(mnt); |
552 | spin_lock(&pin_fs_lock); |
553 | if (!*mount) |
554 | *mount = mnt; |
555 | } |
556 | mntget(*mount); |
557 | ++*count; |
558 | spin_unlock(&pin_fs_lock); |
559 | mntput(mnt); |
560 | return 0; |
561 | } |
562 | EXPORT_SYMBOL(simple_pin_fs); |
563 | |
564 | void simple_release_fs(struct vfsmount **mount, int *count) |
565 | { |
566 | struct vfsmount *mnt; |
567 | spin_lock(&pin_fs_lock); |
568 | mnt = *mount; |
569 | if (!--*count) |
570 | *mount = NULL; |
571 | spin_unlock(&pin_fs_lock); |
572 | mntput(mnt); |
573 | } |
574 | EXPORT_SYMBOL(simple_release_fs); |
575 | |
576 | /** |
577 | * simple_read_from_buffer - copy data from the buffer to user space |
578 | * @to: the user space buffer to read to |
579 | * @count: the maximum number of bytes to read |
580 | * @ppos: the current position in the buffer |
581 | * @from: the buffer to read from |
582 | * @available: the size of the buffer |
583 | * |
584 | * The simple_read_from_buffer() function reads up to @count bytes from the |
585 | * buffer @from at offset @ppos into the user space address starting at @to. |
586 | * |
587 | * On success, the number of bytes read is returned and the offset @ppos is |
588 | * advanced by this number, or negative value is returned on error. |
589 | **/ |
590 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
591 | const void *from, size_t available) |
592 | { |
593 | loff_t pos = *ppos; |
594 | size_t ret; |
595 | |
596 | if (pos < 0) |
597 | return -EINVAL; |
598 | if (pos >= available || !count) |
599 | return 0; |
600 | if (count > available - pos) |
601 | count = available - pos; |
602 | ret = copy_to_user(to, from + pos, count); |
603 | if (ret == count) |
604 | return -EFAULT; |
605 | count -= ret; |
606 | *ppos = pos + count; |
607 | return count; |
608 | } |
609 | EXPORT_SYMBOL(simple_read_from_buffer); |
610 | |
611 | /** |
612 | * simple_write_to_buffer - copy data from user space to the buffer |
613 | * @to: the buffer to write to |
614 | * @available: the size of the buffer |
615 | * @ppos: the current position in the buffer |
616 | * @from: the user space buffer to read from |
617 | * @count: the maximum number of bytes to read |
618 | * |
619 | * The simple_write_to_buffer() function reads up to @count bytes from the user |
620 | * space address starting at @from into the buffer @to at offset @ppos. |
621 | * |
622 | * On success, the number of bytes written is returned and the offset @ppos is |
623 | * advanced by this number, or negative value is returned on error. |
624 | **/ |
625 | ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, |
626 | const void __user *from, size_t count) |
627 | { |
628 | loff_t pos = *ppos; |
629 | size_t res; |
630 | |
631 | if (pos < 0) |
632 | return -EINVAL; |
633 | if (pos >= available || !count) |
634 | return 0; |
635 | if (count > available - pos) |
636 | count = available - pos; |
637 | res = copy_from_user(to + pos, from, count); |
638 | if (res == count) |
639 | return -EFAULT; |
640 | count -= res; |
641 | *ppos = pos + count; |
642 | return count; |
643 | } |
644 | EXPORT_SYMBOL(simple_write_to_buffer); |
645 | |
646 | /** |
647 | * memory_read_from_buffer - copy data from the buffer |
648 | * @to: the kernel space buffer to read to |
649 | * @count: the maximum number of bytes to read |
650 | * @ppos: the current position in the buffer |
651 | * @from: the buffer to read from |
652 | * @available: the size of the buffer |
653 | * |
654 | * The memory_read_from_buffer() function reads up to @count bytes from the |
655 | * buffer @from at offset @ppos into the kernel space address starting at @to. |
656 | * |
657 | * On success, the number of bytes read is returned and the offset @ppos is |
658 | * advanced by this number, or negative value is returned on error. |
659 | **/ |
660 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
661 | const void *from, size_t available) |
662 | { |
663 | loff_t pos = *ppos; |
664 | |
665 | if (pos < 0) |
666 | return -EINVAL; |
667 | if (pos >= available) |
668 | return 0; |
669 | if (count > available - pos) |
670 | count = available - pos; |
671 | memcpy(to, from + pos, count); |
672 | *ppos = pos + count; |
673 | |
674 | return count; |
675 | } |
676 | EXPORT_SYMBOL(memory_read_from_buffer); |
677 | |
678 | /* |
679 | * Transaction based IO. |
680 | * The file expects a single write which triggers the transaction, and then |
681 | * possibly a read which collects the result - which is stored in a |
682 | * file-local buffer. |
683 | */ |
684 | |
685 | void simple_transaction_set(struct file *file, size_t n) |
686 | { |
687 | struct simple_transaction_argresp *ar = file->private_data; |
688 | |
689 | BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); |
690 | |
691 | /* |
692 | * The barrier ensures that ar->size will really remain zero until |
693 | * ar->data is ready for reading. |
694 | */ |
695 | smp_mb(); |
696 | ar->size = n; |
697 | } |
698 | EXPORT_SYMBOL(simple_transaction_set); |
699 | |
700 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
701 | { |
702 | struct simple_transaction_argresp *ar; |
703 | static DEFINE_SPINLOCK(simple_transaction_lock); |
704 | |
705 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) |
706 | return ERR_PTR(-EFBIG); |
707 | |
708 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); |
709 | if (!ar) |
710 | return ERR_PTR(-ENOMEM); |
711 | |
712 | spin_lock(&simple_transaction_lock); |
713 | |
714 | /* only one write allowed per open */ |
715 | if (file->private_data) { |
716 | spin_unlock(&simple_transaction_lock); |
717 | free_page((unsigned long)ar); |
718 | return ERR_PTR(-EBUSY); |
719 | } |
720 | |
721 | file->private_data = ar; |
722 | |
723 | spin_unlock(&simple_transaction_lock); |
724 | |
725 | if (copy_from_user(ar->data, buf, size)) |
726 | return ERR_PTR(-EFAULT); |
727 | |
728 | return ar->data; |
729 | } |
730 | EXPORT_SYMBOL(simple_transaction_get); |
731 | |
732 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) |
733 | { |
734 | struct simple_transaction_argresp *ar = file->private_data; |
735 | |
736 | if (!ar) |
737 | return 0; |
738 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); |
739 | } |
740 | EXPORT_SYMBOL(simple_transaction_read); |
741 | |
742 | int simple_transaction_release(struct inode *inode, struct file *file) |
743 | { |
744 | free_page((unsigned long)file->private_data); |
745 | return 0; |
746 | } |
747 | EXPORT_SYMBOL(simple_transaction_release); |
748 | |
749 | /* Simple attribute files */ |
750 | |
751 | struct simple_attr { |
752 | int (*get)(void *, u64 *); |
753 | int (*set)(void *, u64); |
754 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
755 | char set_buf[24]; |
756 | void *data; |
757 | const char *fmt; /* format for read operation */ |
758 | struct mutex mutex; /* protects access to these buffers */ |
759 | }; |
760 | |
761 | /* simple_attr_open is called by an actual attribute open file operation |
762 | * to set the attribute specific access operations. */ |
763 | int simple_attr_open(struct inode *inode, struct file *file, |
764 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
765 | const char *fmt) |
766 | { |
767 | struct simple_attr *attr; |
768 | |
769 | attr = kmalloc(sizeof(*attr), GFP_KERNEL); |
770 | if (!attr) |
771 | return -ENOMEM; |
772 | |
773 | attr->get = get; |
774 | attr->set = set; |
775 | attr->data = inode->i_private; |
776 | attr->fmt = fmt; |
777 | mutex_init(&attr->mutex); |
778 | |
779 | file->private_data = attr; |
780 | |
781 | return nonseekable_open(inode, file); |
782 | } |
783 | EXPORT_SYMBOL_GPL(simple_attr_open); |
784 | |
785 | int simple_attr_release(struct inode *inode, struct file *file) |
786 | { |
787 | kfree(file->private_data); |
788 | return 0; |
789 | } |
790 | EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */ |
791 | |
792 | /* read from the buffer that is filled with the get function */ |
793 | ssize_t simple_attr_read(struct file *file, char __user *buf, |
794 | size_t len, loff_t *ppos) |
795 | { |
796 | struct simple_attr *attr; |
797 | size_t size; |
798 | ssize_t ret; |
799 | |
800 | attr = file->private_data; |
801 | |
802 | if (!attr->get) |
803 | return -EACCES; |
804 | |
805 | ret = mutex_lock_interruptible(&attr->mutex); |
806 | if (ret) |
807 | return ret; |
808 | |
809 | if (*ppos) { /* continued read */ |
810 | size = strlen(attr->get_buf); |
811 | } else { /* first read */ |
812 | u64 val; |
813 | ret = attr->get(attr->data, &val); |
814 | if (ret) |
815 | goto out; |
816 | |
817 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
818 | attr->fmt, (unsigned long long)val); |
819 | } |
820 | |
821 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); |
822 | out: |
823 | mutex_unlock(&attr->mutex); |
824 | return ret; |
825 | } |
826 | EXPORT_SYMBOL_GPL(simple_attr_read); |
827 | |
828 | /* interpret the buffer as a number to call the set function with */ |
829 | ssize_t simple_attr_write(struct file *file, const char __user *buf, |
830 | size_t len, loff_t *ppos) |
831 | { |
832 | struct simple_attr *attr; |
833 | u64 val; |
834 | size_t size; |
835 | ssize_t ret; |
836 | |
837 | attr = file->private_data; |
838 | if (!attr->set) |
839 | return -EACCES; |
840 | |
841 | ret = mutex_lock_interruptible(&attr->mutex); |
842 | if (ret) |
843 | return ret; |
844 | |
845 | ret = -EFAULT; |
846 | size = min(sizeof(attr->set_buf) - 1, len); |
847 | if (copy_from_user(attr->set_buf, buf, size)) |
848 | goto out; |
849 | |
850 | attr->set_buf[size] = '\0'; |
851 | val = simple_strtoll(attr->set_buf, NULL, 0); |
852 | ret = attr->set(attr->data, val); |
853 | if (ret == 0) |
854 | ret = len; /* on success, claim we got the whole input */ |
855 | out: |
856 | mutex_unlock(&attr->mutex); |
857 | return ret; |
858 | } |
859 | EXPORT_SYMBOL_GPL(simple_attr_write); |
860 | |
861 | /** |
862 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation |
863 | * @sb: filesystem to do the file handle conversion on |
864 | * @fid: file handle to convert |
865 | * @fh_len: length of the file handle in bytes |
866 | * @fh_type: type of file handle |
867 | * @get_inode: filesystem callback to retrieve inode |
868 | * |
869 | * This function decodes @fid as long as it has one of the well-known |
870 | * Linux filehandle types and calls @get_inode on it to retrieve the |
871 | * inode for the object specified in the file handle. |
872 | */ |
873 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, |
874 | int fh_len, int fh_type, struct inode *(*get_inode) |
875 | (struct super_block *sb, u64 ino, u32 gen)) |
876 | { |
877 | struct inode *inode = NULL; |
878 | |
879 | if (fh_len < 2) |
880 | return NULL; |
881 | |
882 | switch (fh_type) { |
883 | case FILEID_INO32_GEN: |
884 | case FILEID_INO32_GEN_PARENT: |
885 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); |
886 | break; |
887 | } |
888 | |
889 | return d_obtain_alias(inode); |
890 | } |
891 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); |
892 | |
893 | /** |
894 | * generic_fh_to_parent - generic helper for the fh_to_parent export operation |
895 | * @sb: filesystem to do the file handle conversion on |
896 | * @fid: file handle to convert |
897 | * @fh_len: length of the file handle in bytes |
898 | * @fh_type: type of file handle |
899 | * @get_inode: filesystem callback to retrieve inode |
900 | * |
901 | * This function decodes @fid as long as it has one of the well-known |
902 | * Linux filehandle types and calls @get_inode on it to retrieve the |
903 | * inode for the _parent_ object specified in the file handle if it |
904 | * is specified in the file handle, or NULL otherwise. |
905 | */ |
906 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, |
907 | int fh_len, int fh_type, struct inode *(*get_inode) |
908 | (struct super_block *sb, u64 ino, u32 gen)) |
909 | { |
910 | struct inode *inode = NULL; |
911 | |
912 | if (fh_len <= 2) |
913 | return NULL; |
914 | |
915 | switch (fh_type) { |
916 | case FILEID_INO32_GEN_PARENT: |
917 | inode = get_inode(sb, fid->i32.parent_ino, |
918 | (fh_len > 3 ? fid->i32.parent_gen : 0)); |
919 | break; |
920 | } |
921 | |
922 | return d_obtain_alias(inode); |
923 | } |
924 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); |
925 | |
926 | /** |
927 | * __generic_file_fsync - generic fsync implementation for simple filesystems |
928 | * |
929 | * @file: file to synchronize |
930 | * @start: start offset in bytes |
931 | * @end: end offset in bytes (inclusive) |
932 | * @datasync: only synchronize essential metadata if true |
933 | * |
934 | * This is a generic implementation of the fsync method for simple |
935 | * filesystems which track all non-inode metadata in the buffers list |
936 | * hanging off the address_space structure. |
937 | */ |
938 | int __generic_file_fsync(struct file *file, loff_t start, loff_t end, |
939 | int datasync) |
940 | { |
941 | struct inode *inode = file->f_mapping->host; |
942 | int err; |
943 | int ret; |
944 | |
945 | err = filemap_write_and_wait_range(inode->i_mapping, start, end); |
946 | if (err) |
947 | return err; |
948 | |
949 | mutex_lock(&inode->i_mutex); |
950 | ret = sync_mapping_buffers(inode->i_mapping); |
951 | if (!(inode->i_state & I_DIRTY)) |
952 | goto out; |
953 | if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) |
954 | goto out; |
955 | |
956 | err = sync_inode_metadata(inode, 1); |
957 | if (ret == 0) |
958 | ret = err; |
959 | |
960 | out: |
961 | mutex_unlock(&inode->i_mutex); |
962 | return ret; |
963 | } |
964 | EXPORT_SYMBOL(__generic_file_fsync); |
965 | |
966 | /** |
967 | * generic_file_fsync - generic fsync implementation for simple filesystems |
968 | * with flush |
969 | * @file: file to synchronize |
970 | * @start: start offset in bytes |
971 | * @end: end offset in bytes (inclusive) |
972 | * @datasync: only synchronize essential metadata if true |
973 | * |
974 | */ |
975 | |
976 | int generic_file_fsync(struct file *file, loff_t start, loff_t end, |
977 | int datasync) |
978 | { |
979 | struct inode *inode = file->f_mapping->host; |
980 | int err; |
981 | |
982 | err = __generic_file_fsync(file, start, end, datasync); |
983 | if (err) |
984 | return err; |
985 | return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); |
986 | } |
987 | EXPORT_SYMBOL(generic_file_fsync); |
988 | |
989 | /** |
990 | * generic_check_addressable - Check addressability of file system |
991 | * @blocksize_bits: log of file system block size |
992 | * @num_blocks: number of blocks in file system |
993 | * |
994 | * Determine whether a file system with @num_blocks blocks (and a |
995 | * block size of 2**@blocksize_bits) is addressable by the sector_t |
996 | * and page cache of the system. Return 0 if so and -EFBIG otherwise. |
997 | */ |
998 | int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) |
999 | { |
1000 | u64 last_fs_block = num_blocks - 1; |
1001 | u64 last_fs_page = |
1002 | last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); |
1003 | |
1004 | if (unlikely(num_blocks == 0)) |
1005 | return 0; |
1006 | |
1007 | if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) |
1008 | return -EINVAL; |
1009 | |
1010 | if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || |
1011 | (last_fs_page > (pgoff_t)(~0ULL))) { |
1012 | return -EFBIG; |
1013 | } |
1014 | return 0; |
1015 | } |
1016 | EXPORT_SYMBOL(generic_check_addressable); |
1017 | |
1018 | /* |
1019 | * No-op implementation of ->fsync for in-memory filesystems. |
1020 | */ |
1021 | int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync) |
1022 | { |
1023 | return 0; |
1024 | } |
1025 | EXPORT_SYMBOL(noop_fsync); |
1026 | |
1027 | void kfree_put_link(struct dentry *dentry, struct nameidata *nd, |
1028 | void *cookie) |
1029 | { |
1030 | char *s = nd_get_link(nd); |
1031 | if (!IS_ERR(s)) |
1032 | kfree(s); |
1033 | } |
1034 | EXPORT_SYMBOL(kfree_put_link); |
1035 | |
1036 | /* |
1037 | * nop .set_page_dirty method so that people can use .page_mkwrite on |
1038 | * anon inodes. |
1039 | */ |
1040 | static int anon_set_page_dirty(struct page *page) |
1041 | { |
1042 | return 0; |
1043 | }; |
1044 | |
1045 | /* |
1046 | * A single inode exists for all anon_inode files. Contrary to pipes, |
1047 | * anon_inode inodes have no associated per-instance data, so we need |
1048 | * only allocate one of them. |
1049 | */ |
1050 | struct inode *alloc_anon_inode(struct super_block *s) |
1051 | { |
1052 | static const struct address_space_operations anon_aops = { |
1053 | .set_page_dirty = anon_set_page_dirty, |
1054 | }; |
1055 | struct inode *inode = new_inode_pseudo(s); |
1056 | |
1057 | if (!inode) |
1058 | return ERR_PTR(-ENOMEM); |
1059 | |
1060 | inode->i_ino = get_next_ino(); |
1061 | inode->i_mapping->a_ops = &anon_aops; |
1062 | |
1063 | /* |
1064 | * Mark the inode dirty from the very beginning, |
1065 | * that way it will never be moved to the dirty |
1066 | * list because mark_inode_dirty() will think |
1067 | * that it already _is_ on the dirty list. |
1068 | */ |
1069 | inode->i_state = I_DIRTY; |
1070 | inode->i_mode = S_IRUSR | S_IWUSR; |
1071 | inode->i_uid = current_fsuid(); |
1072 | inode->i_gid = current_fsgid(); |
1073 | inode->i_flags |= S_PRIVATE; |
1074 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
1075 | return inode; |
1076 | } |
1077 | EXPORT_SYMBOL(alloc_anon_inode); |
1078 |
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