]>
Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * fs/libfs.c | |
3 | * Library for filesystems writers. | |
4 | */ | |
5 | ||
6 | #include <linux/module.h> | |
7 | #include <linux/pagemap.h> | |
8 | #include <linux/mount.h> | |
9 | #include <linux/vfs.h> | |
7cf34c76 | 10 | #include <linux/mutex.h> |
2596110a | 11 | #include <linux/exportfs.h> |
d5aacad5 AV |
12 | #include <linux/writeback.h> |
13 | #include <linux/buffer_head.h> | |
7cf34c76 | 14 | |
1da177e4 LT |
15 | #include <asm/uaccess.h> |
16 | ||
17 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
18 | struct kstat *stat) | |
19 | { | |
20 | struct inode *inode = dentry->d_inode; | |
21 | generic_fillattr(inode, stat); | |
22 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); | |
23 | return 0; | |
24 | } | |
25 | ||
726c3342 | 26 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
1da177e4 | 27 | { |
726c3342 | 28 | buf->f_type = dentry->d_sb->s_magic; |
1da177e4 LT |
29 | buf->f_bsize = PAGE_CACHE_SIZE; |
30 | buf->f_namelen = NAME_MAX; | |
31 | return 0; | |
32 | } | |
33 | ||
34 | /* | |
35 | * Retaining negative dentries for an in-memory filesystem just wastes | |
36 | * memory and lookup time: arrange for them to be deleted immediately. | |
37 | */ | |
38 | static int simple_delete_dentry(struct dentry *dentry) | |
39 | { | |
40 | return 1; | |
41 | } | |
42 | ||
43 | /* | |
44 | * Lookup the data. This is trivial - if the dentry didn't already | |
45 | * exist, we know it is negative. Set d_op to delete negative dentries. | |
46 | */ | |
47 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) | |
48 | { | |
3ba13d17 | 49 | static const struct dentry_operations simple_dentry_operations = { |
1da177e4 LT |
50 | .d_delete = simple_delete_dentry, |
51 | }; | |
52 | ||
53 | if (dentry->d_name.len > NAME_MAX) | |
54 | return ERR_PTR(-ENAMETOOLONG); | |
55 | dentry->d_op = &simple_dentry_operations; | |
56 | d_add(dentry, NULL); | |
57 | return NULL; | |
58 | } | |
59 | ||
60 | int simple_sync_file(struct file * file, struct dentry *dentry, int datasync) | |
61 | { | |
62 | return 0; | |
63 | } | |
64 | ||
65 | int dcache_dir_open(struct inode *inode, struct file *file) | |
66 | { | |
67 | static struct qstr cursor_name = {.len = 1, .name = "."}; | |
68 | ||
0f7fc9e4 | 69 | file->private_data = d_alloc(file->f_path.dentry, &cursor_name); |
1da177e4 LT |
70 | |
71 | return file->private_data ? 0 : -ENOMEM; | |
72 | } | |
73 | ||
74 | int dcache_dir_close(struct inode *inode, struct file *file) | |
75 | { | |
76 | dput(file->private_data); | |
77 | return 0; | |
78 | } | |
79 | ||
80 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) | |
81 | { | |
0f7fc9e4 | 82 | mutex_lock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
83 | switch (origin) { |
84 | case 1: | |
85 | offset += file->f_pos; | |
86 | case 0: | |
87 | if (offset >= 0) | |
88 | break; | |
89 | default: | |
0f7fc9e4 | 90 | mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
91 | return -EINVAL; |
92 | } | |
93 | if (offset != file->f_pos) { | |
94 | file->f_pos = offset; | |
95 | if (file->f_pos >= 2) { | |
96 | struct list_head *p; | |
97 | struct dentry *cursor = file->private_data; | |
98 | loff_t n = file->f_pos - 2; | |
99 | ||
100 | spin_lock(&dcache_lock); | |
5160ee6f | 101 | list_del(&cursor->d_u.d_child); |
0f7fc9e4 JJS |
102 | p = file->f_path.dentry->d_subdirs.next; |
103 | while (n && p != &file->f_path.dentry->d_subdirs) { | |
1da177e4 | 104 | struct dentry *next; |
5160ee6f | 105 | next = list_entry(p, struct dentry, d_u.d_child); |
1da177e4 LT |
106 | if (!d_unhashed(next) && next->d_inode) |
107 | n--; | |
108 | p = p->next; | |
109 | } | |
5160ee6f | 110 | list_add_tail(&cursor->d_u.d_child, p); |
1da177e4 LT |
111 | spin_unlock(&dcache_lock); |
112 | } | |
113 | } | |
0f7fc9e4 | 114 | mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
115 | return offset; |
116 | } | |
117 | ||
118 | /* Relationship between i_mode and the DT_xxx types */ | |
119 | static inline unsigned char dt_type(struct inode *inode) | |
120 | { | |
121 | return (inode->i_mode >> 12) & 15; | |
122 | } | |
123 | ||
124 | /* | |
125 | * Directory is locked and all positive dentries in it are safe, since | |
126 | * for ramfs-type trees they can't go away without unlink() or rmdir(), | |
127 | * both impossible due to the lock on directory. | |
128 | */ | |
129 | ||
130 | int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) | |
131 | { | |
0f7fc9e4 | 132 | struct dentry *dentry = filp->f_path.dentry; |
1da177e4 | 133 | struct dentry *cursor = filp->private_data; |
5160ee6f | 134 | struct list_head *p, *q = &cursor->d_u.d_child; |
1da177e4 LT |
135 | ino_t ino; |
136 | int i = filp->f_pos; | |
137 | ||
138 | switch (i) { | |
139 | case 0: | |
140 | ino = dentry->d_inode->i_ino; | |
141 | if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) | |
142 | break; | |
143 | filp->f_pos++; | |
144 | i++; | |
145 | /* fallthrough */ | |
146 | case 1: | |
147 | ino = parent_ino(dentry); | |
148 | if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) | |
149 | break; | |
150 | filp->f_pos++; | |
151 | i++; | |
152 | /* fallthrough */ | |
153 | default: | |
154 | spin_lock(&dcache_lock); | |
1bfba4e8 AM |
155 | if (filp->f_pos == 2) |
156 | list_move(q, &dentry->d_subdirs); | |
157 | ||
1da177e4 LT |
158 | for (p=q->next; p != &dentry->d_subdirs; p=p->next) { |
159 | struct dentry *next; | |
5160ee6f | 160 | next = list_entry(p, struct dentry, d_u.d_child); |
1da177e4 LT |
161 | if (d_unhashed(next) || !next->d_inode) |
162 | continue; | |
163 | ||
164 | spin_unlock(&dcache_lock); | |
0f8952c2 RN |
165 | if (filldir(dirent, next->d_name.name, |
166 | next->d_name.len, filp->f_pos, | |
167 | next->d_inode->i_ino, | |
168 | dt_type(next->d_inode)) < 0) | |
1da177e4 LT |
169 | return 0; |
170 | spin_lock(&dcache_lock); | |
171 | /* next is still alive */ | |
1bfba4e8 | 172 | list_move(q, p); |
1da177e4 LT |
173 | p = q; |
174 | filp->f_pos++; | |
175 | } | |
176 | spin_unlock(&dcache_lock); | |
177 | } | |
178 | return 0; | |
179 | } | |
180 | ||
181 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) | |
182 | { | |
183 | return -EISDIR; | |
184 | } | |
185 | ||
4b6f5d20 | 186 | const struct file_operations simple_dir_operations = { |
1da177e4 LT |
187 | .open = dcache_dir_open, |
188 | .release = dcache_dir_close, | |
189 | .llseek = dcache_dir_lseek, | |
190 | .read = generic_read_dir, | |
191 | .readdir = dcache_readdir, | |
8ae0b778 | 192 | .fsync = simple_sync_file, |
1da177e4 LT |
193 | }; |
194 | ||
92e1d5be | 195 | const struct inode_operations simple_dir_inode_operations = { |
1da177e4 LT |
196 | .lookup = simple_lookup, |
197 | }; | |
198 | ||
759b9775 HD |
199 | static const struct super_operations simple_super_operations = { |
200 | .statfs = simple_statfs, | |
201 | }; | |
202 | ||
1da177e4 LT |
203 | /* |
204 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that | |
205 | * will never be mountable) | |
206 | */ | |
454e2398 | 207 | int get_sb_pseudo(struct file_system_type *fs_type, char *name, |
ee9b6d61 | 208 | const struct super_operations *ops, unsigned long magic, |
454e2398 | 209 | struct vfsmount *mnt) |
1da177e4 LT |
210 | { |
211 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
1da177e4 LT |
212 | struct dentry *dentry; |
213 | struct inode *root; | |
214 | struct qstr d_name = {.name = name, .len = strlen(name)}; | |
215 | ||
216 | if (IS_ERR(s)) | |
454e2398 | 217 | return PTR_ERR(s); |
1da177e4 LT |
218 | |
219 | s->s_flags = MS_NOUSER; | |
89a4eb4b | 220 | s->s_maxbytes = MAX_LFS_FILESIZE; |
3971e1a9 AN |
221 | s->s_blocksize = PAGE_SIZE; |
222 | s->s_blocksize_bits = PAGE_SHIFT; | |
1da177e4 | 223 | s->s_magic = magic; |
759b9775 | 224 | s->s_op = ops ? ops : &simple_super_operations; |
1da177e4 LT |
225 | s->s_time_gran = 1; |
226 | root = new_inode(s); | |
227 | if (!root) | |
228 | goto Enomem; | |
1a1c9bb4 JL |
229 | /* |
230 | * since this is the first inode, make it number 1. New inodes created | |
231 | * after this must take care not to collide with it (by passing | |
232 | * max_reserved of 1 to iunique). | |
233 | */ | |
234 | root->i_ino = 1; | |
1da177e4 | 235 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
1da177e4 LT |
236 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; |
237 | dentry = d_alloc(NULL, &d_name); | |
238 | if (!dentry) { | |
239 | iput(root); | |
240 | goto Enomem; | |
241 | } | |
242 | dentry->d_sb = s; | |
243 | dentry->d_parent = dentry; | |
244 | d_instantiate(dentry, root); | |
245 | s->s_root = dentry; | |
246 | s->s_flags |= MS_ACTIVE; | |
a3ec947c SB |
247 | simple_set_mnt(mnt, s); |
248 | return 0; | |
1da177e4 LT |
249 | |
250 | Enomem: | |
6f5bbff9 | 251 | deactivate_locked_super(s); |
454e2398 | 252 | return -ENOMEM; |
1da177e4 LT |
253 | } |
254 | ||
255 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
256 | { | |
257 | struct inode *inode = old_dentry->d_inode; | |
258 | ||
259 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
d8c76e6f | 260 | inc_nlink(inode); |
1da177e4 LT |
261 | atomic_inc(&inode->i_count); |
262 | dget(dentry); | |
263 | d_instantiate(dentry, inode); | |
264 | return 0; | |
265 | } | |
266 | ||
267 | static inline int simple_positive(struct dentry *dentry) | |
268 | { | |
269 | return dentry->d_inode && !d_unhashed(dentry); | |
270 | } | |
271 | ||
272 | int simple_empty(struct dentry *dentry) | |
273 | { | |
274 | struct dentry *child; | |
275 | int ret = 0; | |
276 | ||
277 | spin_lock(&dcache_lock); | |
5160ee6f | 278 | list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) |
1da177e4 LT |
279 | if (simple_positive(child)) |
280 | goto out; | |
281 | ret = 1; | |
282 | out: | |
283 | spin_unlock(&dcache_lock); | |
284 | return ret; | |
285 | } | |
286 | ||
287 | int simple_unlink(struct inode *dir, struct dentry *dentry) | |
288 | { | |
289 | struct inode *inode = dentry->d_inode; | |
290 | ||
291 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
9a53c3a7 | 292 | drop_nlink(inode); |
1da177e4 LT |
293 | dput(dentry); |
294 | return 0; | |
295 | } | |
296 | ||
297 | int simple_rmdir(struct inode *dir, struct dentry *dentry) | |
298 | { | |
299 | if (!simple_empty(dentry)) | |
300 | return -ENOTEMPTY; | |
301 | ||
9a53c3a7 | 302 | drop_nlink(dentry->d_inode); |
1da177e4 | 303 | simple_unlink(dir, dentry); |
9a53c3a7 | 304 | drop_nlink(dir); |
1da177e4 LT |
305 | return 0; |
306 | } | |
307 | ||
308 | int simple_rename(struct inode *old_dir, struct dentry *old_dentry, | |
309 | struct inode *new_dir, struct dentry *new_dentry) | |
310 | { | |
311 | struct inode *inode = old_dentry->d_inode; | |
312 | int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); | |
313 | ||
314 | if (!simple_empty(new_dentry)) | |
315 | return -ENOTEMPTY; | |
316 | ||
317 | if (new_dentry->d_inode) { | |
318 | simple_unlink(new_dir, new_dentry); | |
319 | if (they_are_dirs) | |
9a53c3a7 | 320 | drop_nlink(old_dir); |
1da177e4 | 321 | } else if (they_are_dirs) { |
9a53c3a7 | 322 | drop_nlink(old_dir); |
d8c76e6f | 323 | inc_nlink(new_dir); |
1da177e4 LT |
324 | } |
325 | ||
326 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = | |
327 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; | |
328 | ||
329 | return 0; | |
330 | } | |
331 | ||
332 | int simple_readpage(struct file *file, struct page *page) | |
333 | { | |
c0d92cbc | 334 | clear_highpage(page); |
1da177e4 LT |
335 | flush_dcache_page(page); |
336 | SetPageUptodate(page); | |
1da177e4 LT |
337 | unlock_page(page); |
338 | return 0; | |
339 | } | |
340 | ||
afddba49 NP |
341 | int simple_write_begin(struct file *file, struct address_space *mapping, |
342 | loff_t pos, unsigned len, unsigned flags, | |
343 | struct page **pagep, void **fsdata) | |
344 | { | |
345 | struct page *page; | |
346 | pgoff_t index; | |
afddba49 NP |
347 | |
348 | index = pos >> PAGE_CACHE_SHIFT; | |
afddba49 | 349 | |
54566b2c | 350 | page = grab_cache_page_write_begin(mapping, index, flags); |
afddba49 NP |
351 | if (!page) |
352 | return -ENOMEM; | |
353 | ||
354 | *pagep = page; | |
355 | ||
193cf4b9 BH |
356 | if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { |
357 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); | |
358 | ||
359 | zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); | |
360 | } | |
361 | return 0; | |
afddba49 NP |
362 | } |
363 | ||
ad2a722f BH |
364 | /** |
365 | * simple_write_end - .write_end helper for non-block-device FSes | |
366 | * @available: See .write_end of address_space_operations | |
367 | * @file: " | |
368 | * @mapping: " | |
369 | * @pos: " | |
370 | * @len: " | |
371 | * @copied: " | |
372 | * @page: " | |
373 | * @fsdata: " | |
374 | * | |
375 | * simple_write_end does the minimum needed for updating a page after writing is | |
376 | * done. It has the same API signature as the .write_end of | |
377 | * address_space_operations vector. So it can just be set onto .write_end for | |
378 | * FSes that don't need any other processing. i_mutex is assumed to be held. | |
379 | * Block based filesystems should use generic_write_end(). | |
380 | * NOTE: Even though i_size might get updated by this function, mark_inode_dirty | |
381 | * is not called, so a filesystem that actually does store data in .write_inode | |
382 | * should extend on what's done here with a call to mark_inode_dirty() in the | |
383 | * case that i_size has changed. | |
384 | */ | |
afddba49 NP |
385 | int simple_write_end(struct file *file, struct address_space *mapping, |
386 | loff_t pos, unsigned len, unsigned copied, | |
387 | struct page *page, void *fsdata) | |
388 | { | |
ad2a722f BH |
389 | struct inode *inode = page->mapping->host; |
390 | loff_t last_pos = pos + copied; | |
afddba49 NP |
391 | |
392 | /* zero the stale part of the page if we did a short copy */ | |
393 | if (copied < len) { | |
ad2a722f BH |
394 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
395 | ||
396 | zero_user(page, from + copied, len - copied); | |
afddba49 NP |
397 | } |
398 | ||
ad2a722f BH |
399 | if (!PageUptodate(page)) |
400 | SetPageUptodate(page); | |
401 | /* | |
402 | * No need to use i_size_read() here, the i_size | |
403 | * cannot change under us because we hold the i_mutex. | |
404 | */ | |
405 | if (last_pos > inode->i_size) | |
406 | i_size_write(inode, last_pos); | |
afddba49 | 407 | |
ad2a722f | 408 | set_page_dirty(page); |
afddba49 NP |
409 | unlock_page(page); |
410 | page_cache_release(page); | |
411 | ||
412 | return copied; | |
413 | } | |
414 | ||
1a1c9bb4 JL |
415 | /* |
416 | * the inodes created here are not hashed. If you use iunique to generate | |
417 | * unique inode values later for this filesystem, then you must take care | |
418 | * to pass it an appropriate max_reserved value to avoid collisions. | |
419 | */ | |
1da177e4 LT |
420 | int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files) |
421 | { | |
1da177e4 LT |
422 | struct inode *inode; |
423 | struct dentry *root; | |
424 | struct dentry *dentry; | |
425 | int i; | |
426 | ||
427 | s->s_blocksize = PAGE_CACHE_SIZE; | |
428 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
429 | s->s_magic = magic; | |
759b9775 | 430 | s->s_op = &simple_super_operations; |
1da177e4 LT |
431 | s->s_time_gran = 1; |
432 | ||
433 | inode = new_inode(s); | |
434 | if (!inode) | |
435 | return -ENOMEM; | |
1a1c9bb4 JL |
436 | /* |
437 | * because the root inode is 1, the files array must not contain an | |
438 | * entry at index 1 | |
439 | */ | |
440 | inode->i_ino = 1; | |
1da177e4 | 441 | inode->i_mode = S_IFDIR | 0755; |
1da177e4 LT |
442 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
443 | inode->i_op = &simple_dir_inode_operations; | |
444 | inode->i_fop = &simple_dir_operations; | |
7656f328 | 445 | inode->i_nlink = 2; |
1da177e4 LT |
446 | root = d_alloc_root(inode); |
447 | if (!root) { | |
448 | iput(inode); | |
449 | return -ENOMEM; | |
450 | } | |
451 | for (i = 0; !files->name || files->name[0]; i++, files++) { | |
452 | if (!files->name) | |
453 | continue; | |
1a1c9bb4 JL |
454 | |
455 | /* warn if it tries to conflict with the root inode */ | |
456 | if (unlikely(i == 1)) | |
457 | printk(KERN_WARNING "%s: %s passed in a files array" | |
458 | "with an index of 1!\n", __func__, | |
459 | s->s_type->name); | |
460 | ||
1da177e4 LT |
461 | dentry = d_alloc_name(root, files->name); |
462 | if (!dentry) | |
463 | goto out; | |
464 | inode = new_inode(s); | |
465 | if (!inode) | |
466 | goto out; | |
467 | inode->i_mode = S_IFREG | files->mode; | |
1da177e4 LT |
468 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
469 | inode->i_fop = files->ops; | |
470 | inode->i_ino = i; | |
471 | d_add(dentry, inode); | |
472 | } | |
473 | s->s_root = root; | |
474 | return 0; | |
475 | out: | |
476 | d_genocide(root); | |
477 | dput(root); | |
478 | return -ENOMEM; | |
479 | } | |
480 | ||
481 | static DEFINE_SPINLOCK(pin_fs_lock); | |
482 | ||
1f5ce9e9 | 483 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
1da177e4 LT |
484 | { |
485 | struct vfsmount *mnt = NULL; | |
486 | spin_lock(&pin_fs_lock); | |
487 | if (unlikely(!*mount)) { | |
488 | spin_unlock(&pin_fs_lock); | |
1f5ce9e9 | 489 | mnt = vfs_kern_mount(type, 0, type->name, NULL); |
1da177e4 LT |
490 | if (IS_ERR(mnt)) |
491 | return PTR_ERR(mnt); | |
492 | spin_lock(&pin_fs_lock); | |
493 | if (!*mount) | |
494 | *mount = mnt; | |
495 | } | |
496 | mntget(*mount); | |
497 | ++*count; | |
498 | spin_unlock(&pin_fs_lock); | |
499 | mntput(mnt); | |
500 | return 0; | |
501 | } | |
502 | ||
503 | void simple_release_fs(struct vfsmount **mount, int *count) | |
504 | { | |
505 | struct vfsmount *mnt; | |
506 | spin_lock(&pin_fs_lock); | |
507 | mnt = *mount; | |
508 | if (!--*count) | |
509 | *mount = NULL; | |
510 | spin_unlock(&pin_fs_lock); | |
511 | mntput(mnt); | |
512 | } | |
513 | ||
6d1029b5 AM |
514 | /** |
515 | * simple_read_from_buffer - copy data from the buffer to user space | |
516 | * @to: the user space buffer to read to | |
517 | * @count: the maximum number of bytes to read | |
518 | * @ppos: the current position in the buffer | |
519 | * @from: the buffer to read from | |
520 | * @available: the size of the buffer | |
521 | * | |
522 | * The simple_read_from_buffer() function reads up to @count bytes from the | |
523 | * buffer @from at offset @ppos into the user space address starting at @to. | |
524 | * | |
525 | * On success, the number of bytes read is returned and the offset @ppos is | |
526 | * advanced by this number, or negative value is returned on error. | |
527 | **/ | |
1da177e4 LT |
528 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
529 | const void *from, size_t available) | |
530 | { | |
531 | loff_t pos = *ppos; | |
14be2746 SR |
532 | size_t ret; |
533 | ||
1da177e4 LT |
534 | if (pos < 0) |
535 | return -EINVAL; | |
14be2746 | 536 | if (pos >= available || !count) |
1da177e4 LT |
537 | return 0; |
538 | if (count > available - pos) | |
539 | count = available - pos; | |
14be2746 SR |
540 | ret = copy_to_user(to, from + pos, count); |
541 | if (ret == count) | |
1da177e4 | 542 | return -EFAULT; |
14be2746 | 543 | count -= ret; |
1da177e4 LT |
544 | *ppos = pos + count; |
545 | return count; | |
546 | } | |
547 | ||
6d1029b5 AM |
548 | /** |
549 | * memory_read_from_buffer - copy data from the buffer | |
550 | * @to: the kernel space buffer to read to | |
551 | * @count: the maximum number of bytes to read | |
552 | * @ppos: the current position in the buffer | |
553 | * @from: the buffer to read from | |
554 | * @available: the size of the buffer | |
555 | * | |
556 | * The memory_read_from_buffer() function reads up to @count bytes from the | |
557 | * buffer @from at offset @ppos into the kernel space address starting at @to. | |
558 | * | |
559 | * On success, the number of bytes read is returned and the offset @ppos is | |
560 | * advanced by this number, or negative value is returned on error. | |
561 | **/ | |
93b07113 AM |
562 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
563 | const void *from, size_t available) | |
564 | { | |
565 | loff_t pos = *ppos; | |
566 | ||
567 | if (pos < 0) | |
568 | return -EINVAL; | |
569 | if (pos >= available) | |
570 | return 0; | |
571 | if (count > available - pos) | |
572 | count = available - pos; | |
573 | memcpy(to, from + pos, count); | |
574 | *ppos = pos + count; | |
575 | ||
576 | return count; | |
577 | } | |
578 | ||
1da177e4 LT |
579 | /* |
580 | * Transaction based IO. | |
581 | * The file expects a single write which triggers the transaction, and then | |
582 | * possibly a read which collects the result - which is stored in a | |
583 | * file-local buffer. | |
584 | */ | |
76791ab2 IM |
585 | |
586 | void simple_transaction_set(struct file *file, size_t n) | |
587 | { | |
588 | struct simple_transaction_argresp *ar = file->private_data; | |
589 | ||
590 | BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); | |
591 | ||
592 | /* | |
593 | * The barrier ensures that ar->size will really remain zero until | |
594 | * ar->data is ready for reading. | |
595 | */ | |
596 | smp_mb(); | |
597 | ar->size = n; | |
598 | } | |
599 | ||
1da177e4 LT |
600 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
601 | { | |
602 | struct simple_transaction_argresp *ar; | |
603 | static DEFINE_SPINLOCK(simple_transaction_lock); | |
604 | ||
605 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) | |
606 | return ERR_PTR(-EFBIG); | |
607 | ||
608 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); | |
609 | if (!ar) | |
610 | return ERR_PTR(-ENOMEM); | |
611 | ||
612 | spin_lock(&simple_transaction_lock); | |
613 | ||
614 | /* only one write allowed per open */ | |
615 | if (file->private_data) { | |
616 | spin_unlock(&simple_transaction_lock); | |
617 | free_page((unsigned long)ar); | |
618 | return ERR_PTR(-EBUSY); | |
619 | } | |
620 | ||
621 | file->private_data = ar; | |
622 | ||
623 | spin_unlock(&simple_transaction_lock); | |
624 | ||
625 | if (copy_from_user(ar->data, buf, size)) | |
626 | return ERR_PTR(-EFAULT); | |
627 | ||
628 | return ar->data; | |
629 | } | |
630 | ||
631 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) | |
632 | { | |
633 | struct simple_transaction_argresp *ar = file->private_data; | |
634 | ||
635 | if (!ar) | |
636 | return 0; | |
637 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); | |
638 | } | |
639 | ||
640 | int simple_transaction_release(struct inode *inode, struct file *file) | |
641 | { | |
642 | free_page((unsigned long)file->private_data); | |
643 | return 0; | |
644 | } | |
645 | ||
acaefc25 AB |
646 | /* Simple attribute files */ |
647 | ||
648 | struct simple_attr { | |
8b88b099 CH |
649 | int (*get)(void *, u64 *); |
650 | int (*set)(void *, u64); | |
acaefc25 AB |
651 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
652 | char set_buf[24]; | |
653 | void *data; | |
654 | const char *fmt; /* format for read operation */ | |
7cf34c76 | 655 | struct mutex mutex; /* protects access to these buffers */ |
acaefc25 AB |
656 | }; |
657 | ||
658 | /* simple_attr_open is called by an actual attribute open file operation | |
659 | * to set the attribute specific access operations. */ | |
660 | int simple_attr_open(struct inode *inode, struct file *file, | |
8b88b099 | 661 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
acaefc25 AB |
662 | const char *fmt) |
663 | { | |
664 | struct simple_attr *attr; | |
665 | ||
666 | attr = kmalloc(sizeof(*attr), GFP_KERNEL); | |
667 | if (!attr) | |
668 | return -ENOMEM; | |
669 | ||
670 | attr->get = get; | |
671 | attr->set = set; | |
8e18e294 | 672 | attr->data = inode->i_private; |
acaefc25 | 673 | attr->fmt = fmt; |
7cf34c76 | 674 | mutex_init(&attr->mutex); |
acaefc25 AB |
675 | |
676 | file->private_data = attr; | |
677 | ||
678 | return nonseekable_open(inode, file); | |
679 | } | |
680 | ||
74bedc4d | 681 | int simple_attr_release(struct inode *inode, struct file *file) |
acaefc25 AB |
682 | { |
683 | kfree(file->private_data); | |
684 | return 0; | |
685 | } | |
686 | ||
687 | /* read from the buffer that is filled with the get function */ | |
688 | ssize_t simple_attr_read(struct file *file, char __user *buf, | |
689 | size_t len, loff_t *ppos) | |
690 | { | |
691 | struct simple_attr *attr; | |
692 | size_t size; | |
693 | ssize_t ret; | |
694 | ||
695 | attr = file->private_data; | |
696 | ||
697 | if (!attr->get) | |
698 | return -EACCES; | |
699 | ||
9261303a CH |
700 | ret = mutex_lock_interruptible(&attr->mutex); |
701 | if (ret) | |
702 | return ret; | |
703 | ||
8b88b099 | 704 | if (*ppos) { /* continued read */ |
acaefc25 | 705 | size = strlen(attr->get_buf); |
8b88b099 CH |
706 | } else { /* first read */ |
707 | u64 val; | |
708 | ret = attr->get(attr->data, &val); | |
709 | if (ret) | |
710 | goto out; | |
711 | ||
acaefc25 | 712 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
8b88b099 CH |
713 | attr->fmt, (unsigned long long)val); |
714 | } | |
acaefc25 AB |
715 | |
716 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); | |
8b88b099 | 717 | out: |
7cf34c76 | 718 | mutex_unlock(&attr->mutex); |
acaefc25 AB |
719 | return ret; |
720 | } | |
721 | ||
722 | /* interpret the buffer as a number to call the set function with */ | |
723 | ssize_t simple_attr_write(struct file *file, const char __user *buf, | |
724 | size_t len, loff_t *ppos) | |
725 | { | |
726 | struct simple_attr *attr; | |
727 | u64 val; | |
728 | size_t size; | |
729 | ssize_t ret; | |
730 | ||
731 | attr = file->private_data; | |
acaefc25 AB |
732 | if (!attr->set) |
733 | return -EACCES; | |
734 | ||
9261303a CH |
735 | ret = mutex_lock_interruptible(&attr->mutex); |
736 | if (ret) | |
737 | return ret; | |
738 | ||
acaefc25 AB |
739 | ret = -EFAULT; |
740 | size = min(sizeof(attr->set_buf) - 1, len); | |
741 | if (copy_from_user(attr->set_buf, buf, size)) | |
742 | goto out; | |
743 | ||
acaefc25 AB |
744 | attr->set_buf[size] = '\0'; |
745 | val = simple_strtol(attr->set_buf, NULL, 0); | |
05cc0cee WF |
746 | ret = attr->set(attr->data, val); |
747 | if (ret == 0) | |
748 | ret = len; /* on success, claim we got the whole input */ | |
acaefc25 | 749 | out: |
7cf34c76 | 750 | mutex_unlock(&attr->mutex); |
acaefc25 AB |
751 | return ret; |
752 | } | |
753 | ||
2596110a CH |
754 | /** |
755 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation | |
756 | * @sb: filesystem to do the file handle conversion on | |
757 | * @fid: file handle to convert | |
758 | * @fh_len: length of the file handle in bytes | |
759 | * @fh_type: type of file handle | |
760 | * @get_inode: filesystem callback to retrieve inode | |
761 | * | |
762 | * This function decodes @fid as long as it has one of the well-known | |
763 | * Linux filehandle types and calls @get_inode on it to retrieve the | |
764 | * inode for the object specified in the file handle. | |
765 | */ | |
766 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, | |
767 | int fh_len, int fh_type, struct inode *(*get_inode) | |
768 | (struct super_block *sb, u64 ino, u32 gen)) | |
769 | { | |
770 | struct inode *inode = NULL; | |
771 | ||
772 | if (fh_len < 2) | |
773 | return NULL; | |
774 | ||
775 | switch (fh_type) { | |
776 | case FILEID_INO32_GEN: | |
777 | case FILEID_INO32_GEN_PARENT: | |
778 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); | |
779 | break; | |
780 | } | |
781 | ||
4ea3ada2 | 782 | return d_obtain_alias(inode); |
2596110a CH |
783 | } |
784 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); | |
785 | ||
786 | /** | |
787 | * generic_fh_to_dentry - generic helper for the fh_to_parent export operation | |
788 | * @sb: filesystem to do the file handle conversion on | |
789 | * @fid: file handle to convert | |
790 | * @fh_len: length of the file handle in bytes | |
791 | * @fh_type: type of file handle | |
792 | * @get_inode: filesystem callback to retrieve inode | |
793 | * | |
794 | * This function decodes @fid as long as it has one of the well-known | |
795 | * Linux filehandle types and calls @get_inode on it to retrieve the | |
796 | * inode for the _parent_ object specified in the file handle if it | |
797 | * is specified in the file handle, or NULL otherwise. | |
798 | */ | |
799 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, | |
800 | int fh_len, int fh_type, struct inode *(*get_inode) | |
801 | (struct super_block *sb, u64 ino, u32 gen)) | |
802 | { | |
803 | struct inode *inode = NULL; | |
804 | ||
805 | if (fh_len <= 2) | |
806 | return NULL; | |
807 | ||
808 | switch (fh_type) { | |
809 | case FILEID_INO32_GEN_PARENT: | |
810 | inode = get_inode(sb, fid->i32.parent_ino, | |
811 | (fh_len > 3 ? fid->i32.parent_gen : 0)); | |
812 | break; | |
813 | } | |
814 | ||
4ea3ada2 | 815 | return d_obtain_alias(inode); |
2596110a CH |
816 | } |
817 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); | |
818 | ||
d5aacad5 AV |
819 | int simple_fsync(struct file *file, struct dentry *dentry, int datasync) |
820 | { | |
821 | struct writeback_control wbc = { | |
822 | .sync_mode = WB_SYNC_ALL, | |
823 | .nr_to_write = 0, /* metadata-only; caller takes care of data */ | |
824 | }; | |
825 | struct inode *inode = dentry->d_inode; | |
826 | int err; | |
827 | int ret; | |
828 | ||
829 | ret = sync_mapping_buffers(inode->i_mapping); | |
830 | if (!(inode->i_state & I_DIRTY)) | |
831 | return ret; | |
832 | if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) | |
833 | return ret; | |
834 | ||
835 | err = sync_inode(inode, &wbc); | |
836 | if (ret == 0) | |
837 | ret = err; | |
838 | return ret; | |
839 | } | |
840 | EXPORT_SYMBOL(simple_fsync); | |
841 | ||
1da177e4 LT |
842 | EXPORT_SYMBOL(dcache_dir_close); |
843 | EXPORT_SYMBOL(dcache_dir_lseek); | |
844 | EXPORT_SYMBOL(dcache_dir_open); | |
845 | EXPORT_SYMBOL(dcache_readdir); | |
846 | EXPORT_SYMBOL(generic_read_dir); | |
847 | EXPORT_SYMBOL(get_sb_pseudo); | |
afddba49 NP |
848 | EXPORT_SYMBOL(simple_write_begin); |
849 | EXPORT_SYMBOL(simple_write_end); | |
1da177e4 LT |
850 | EXPORT_SYMBOL(simple_dir_inode_operations); |
851 | EXPORT_SYMBOL(simple_dir_operations); | |
852 | EXPORT_SYMBOL(simple_empty); | |
1da177e4 LT |
853 | EXPORT_SYMBOL(simple_fill_super); |
854 | EXPORT_SYMBOL(simple_getattr); | |
855 | EXPORT_SYMBOL(simple_link); | |
856 | EXPORT_SYMBOL(simple_lookup); | |
857 | EXPORT_SYMBOL(simple_pin_fs); | |
1da177e4 LT |
858 | EXPORT_SYMBOL(simple_readpage); |
859 | EXPORT_SYMBOL(simple_release_fs); | |
860 | EXPORT_SYMBOL(simple_rename); | |
861 | EXPORT_SYMBOL(simple_rmdir); | |
862 | EXPORT_SYMBOL(simple_statfs); | |
863 | EXPORT_SYMBOL(simple_sync_file); | |
864 | EXPORT_SYMBOL(simple_unlink); | |
865 | EXPORT_SYMBOL(simple_read_from_buffer); | |
93b07113 | 866 | EXPORT_SYMBOL(memory_read_from_buffer); |
76791ab2 | 867 | EXPORT_SYMBOL(simple_transaction_set); |
1da177e4 LT |
868 | EXPORT_SYMBOL(simple_transaction_get); |
869 | EXPORT_SYMBOL(simple_transaction_read); | |
870 | EXPORT_SYMBOL(simple_transaction_release); | |
acaefc25 | 871 | EXPORT_SYMBOL_GPL(simple_attr_open); |
74bedc4d | 872 | EXPORT_SYMBOL_GPL(simple_attr_release); |
acaefc25 AB |
873 | EXPORT_SYMBOL_GPL(simple_attr_read); |
874 | EXPORT_SYMBOL_GPL(simple_attr_write); |