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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> |
7cf34c76 | 12 | |
1da177e4 LT |
13 | #include <asm/uaccess.h> |
14 | ||
15 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
16 | struct kstat *stat) | |
17 | { | |
18 | struct inode *inode = dentry->d_inode; | |
19 | generic_fillattr(inode, stat); | |
20 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); | |
21 | return 0; | |
22 | } | |
23 | ||
726c3342 | 24 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
1da177e4 | 25 | { |
726c3342 | 26 | buf->f_type = dentry->d_sb->s_magic; |
1da177e4 LT |
27 | buf->f_bsize = PAGE_CACHE_SIZE; |
28 | buf->f_namelen = NAME_MAX; | |
29 | return 0; | |
30 | } | |
31 | ||
32 | /* | |
33 | * Retaining negative dentries for an in-memory filesystem just wastes | |
34 | * memory and lookup time: arrange for them to be deleted immediately. | |
35 | */ | |
36 | static int simple_delete_dentry(struct dentry *dentry) | |
37 | { | |
38 | return 1; | |
39 | } | |
40 | ||
41 | /* | |
42 | * Lookup the data. This is trivial - if the dentry didn't already | |
43 | * exist, we know it is negative. Set d_op to delete negative dentries. | |
44 | */ | |
45 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) | |
46 | { | |
3ba13d17 | 47 | static const struct dentry_operations simple_dentry_operations = { |
1da177e4 LT |
48 | .d_delete = simple_delete_dentry, |
49 | }; | |
50 | ||
51 | if (dentry->d_name.len > NAME_MAX) | |
52 | return ERR_PTR(-ENAMETOOLONG); | |
53 | dentry->d_op = &simple_dentry_operations; | |
54 | d_add(dentry, NULL); | |
55 | return NULL; | |
56 | } | |
57 | ||
58 | int simple_sync_file(struct file * file, struct dentry *dentry, int datasync) | |
59 | { | |
60 | return 0; | |
61 | } | |
62 | ||
63 | int dcache_dir_open(struct inode *inode, struct file *file) | |
64 | { | |
65 | static struct qstr cursor_name = {.len = 1, .name = "."}; | |
66 | ||
0f7fc9e4 | 67 | file->private_data = d_alloc(file->f_path.dentry, &cursor_name); |
1da177e4 LT |
68 | |
69 | return file->private_data ? 0 : -ENOMEM; | |
70 | } | |
71 | ||
72 | int dcache_dir_close(struct inode *inode, struct file *file) | |
73 | { | |
74 | dput(file->private_data); | |
75 | return 0; | |
76 | } | |
77 | ||
78 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) | |
79 | { | |
0f7fc9e4 | 80 | mutex_lock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
81 | switch (origin) { |
82 | case 1: | |
83 | offset += file->f_pos; | |
84 | case 0: | |
85 | if (offset >= 0) | |
86 | break; | |
87 | default: | |
0f7fc9e4 | 88 | mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
89 | return -EINVAL; |
90 | } | |
91 | if (offset != file->f_pos) { | |
92 | file->f_pos = offset; | |
93 | if (file->f_pos >= 2) { | |
94 | struct list_head *p; | |
95 | struct dentry *cursor = file->private_data; | |
96 | loff_t n = file->f_pos - 2; | |
97 | ||
98 | spin_lock(&dcache_lock); | |
5160ee6f | 99 | list_del(&cursor->d_u.d_child); |
0f7fc9e4 JJS |
100 | p = file->f_path.dentry->d_subdirs.next; |
101 | while (n && p != &file->f_path.dentry->d_subdirs) { | |
1da177e4 | 102 | struct dentry *next; |
5160ee6f | 103 | next = list_entry(p, struct dentry, d_u.d_child); |
1da177e4 LT |
104 | if (!d_unhashed(next) && next->d_inode) |
105 | n--; | |
106 | p = p->next; | |
107 | } | |
5160ee6f | 108 | list_add_tail(&cursor->d_u.d_child, p); |
1da177e4 LT |
109 | spin_unlock(&dcache_lock); |
110 | } | |
111 | } | |
0f7fc9e4 | 112 | mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
113 | return offset; |
114 | } | |
115 | ||
116 | /* Relationship between i_mode and the DT_xxx types */ | |
117 | static inline unsigned char dt_type(struct inode *inode) | |
118 | { | |
119 | return (inode->i_mode >> 12) & 15; | |
120 | } | |
121 | ||
122 | /* | |
123 | * Directory is locked and all positive dentries in it are safe, since | |
124 | * for ramfs-type trees they can't go away without unlink() or rmdir(), | |
125 | * both impossible due to the lock on directory. | |
126 | */ | |
127 | ||
128 | int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) | |
129 | { | |
0f7fc9e4 | 130 | struct dentry *dentry = filp->f_path.dentry; |
1da177e4 | 131 | struct dentry *cursor = filp->private_data; |
5160ee6f | 132 | struct list_head *p, *q = &cursor->d_u.d_child; |
1da177e4 LT |
133 | ino_t ino; |
134 | int i = filp->f_pos; | |
135 | ||
136 | switch (i) { | |
137 | case 0: | |
138 | ino = dentry->d_inode->i_ino; | |
139 | if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) | |
140 | break; | |
141 | filp->f_pos++; | |
142 | i++; | |
143 | /* fallthrough */ | |
144 | case 1: | |
145 | ino = parent_ino(dentry); | |
146 | if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) | |
147 | break; | |
148 | filp->f_pos++; | |
149 | i++; | |
150 | /* fallthrough */ | |
151 | default: | |
152 | spin_lock(&dcache_lock); | |
1bfba4e8 AM |
153 | if (filp->f_pos == 2) |
154 | list_move(q, &dentry->d_subdirs); | |
155 | ||
1da177e4 LT |
156 | for (p=q->next; p != &dentry->d_subdirs; p=p->next) { |
157 | struct dentry *next; | |
5160ee6f | 158 | next = list_entry(p, struct dentry, d_u.d_child); |
1da177e4 LT |
159 | if (d_unhashed(next) || !next->d_inode) |
160 | continue; | |
161 | ||
162 | spin_unlock(&dcache_lock); | |
0f8952c2 RN |
163 | if (filldir(dirent, next->d_name.name, |
164 | next->d_name.len, filp->f_pos, | |
165 | next->d_inode->i_ino, | |
166 | dt_type(next->d_inode)) < 0) | |
1da177e4 LT |
167 | return 0; |
168 | spin_lock(&dcache_lock); | |
169 | /* next is still alive */ | |
1bfba4e8 | 170 | list_move(q, p); |
1da177e4 LT |
171 | p = q; |
172 | filp->f_pos++; | |
173 | } | |
174 | spin_unlock(&dcache_lock); | |
175 | } | |
176 | return 0; | |
177 | } | |
178 | ||
179 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) | |
180 | { | |
181 | return -EISDIR; | |
182 | } | |
183 | ||
4b6f5d20 | 184 | const struct file_operations simple_dir_operations = { |
1da177e4 LT |
185 | .open = dcache_dir_open, |
186 | .release = dcache_dir_close, | |
187 | .llseek = dcache_dir_lseek, | |
188 | .read = generic_read_dir, | |
189 | .readdir = dcache_readdir, | |
8ae0b778 | 190 | .fsync = simple_sync_file, |
1da177e4 LT |
191 | }; |
192 | ||
92e1d5be | 193 | const struct inode_operations simple_dir_inode_operations = { |
1da177e4 LT |
194 | .lookup = simple_lookup, |
195 | }; | |
196 | ||
759b9775 HD |
197 | static const struct super_operations simple_super_operations = { |
198 | .statfs = simple_statfs, | |
199 | }; | |
200 | ||
1da177e4 LT |
201 | /* |
202 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that | |
203 | * will never be mountable) | |
204 | */ | |
454e2398 | 205 | int get_sb_pseudo(struct file_system_type *fs_type, char *name, |
ee9b6d61 | 206 | const struct super_operations *ops, unsigned long magic, |
454e2398 | 207 | struct vfsmount *mnt) |
1da177e4 LT |
208 | { |
209 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
1da177e4 LT |
210 | struct dentry *dentry; |
211 | struct inode *root; | |
212 | struct qstr d_name = {.name = name, .len = strlen(name)}; | |
213 | ||
214 | if (IS_ERR(s)) | |
454e2398 | 215 | return PTR_ERR(s); |
1da177e4 LT |
216 | |
217 | s->s_flags = MS_NOUSER; | |
218 | s->s_maxbytes = ~0ULL; | |
3971e1a9 AN |
219 | s->s_blocksize = PAGE_SIZE; |
220 | s->s_blocksize_bits = PAGE_SHIFT; | |
1da177e4 | 221 | s->s_magic = magic; |
759b9775 | 222 | s->s_op = ops ? ops : &simple_super_operations; |
1da177e4 LT |
223 | s->s_time_gran = 1; |
224 | root = new_inode(s); | |
225 | if (!root) | |
226 | goto Enomem; | |
1a1c9bb4 JL |
227 | /* |
228 | * since this is the first inode, make it number 1. New inodes created | |
229 | * after this must take care not to collide with it (by passing | |
230 | * max_reserved of 1 to iunique). | |
231 | */ | |
232 | root->i_ino = 1; | |
1da177e4 | 233 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
1da177e4 LT |
234 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; |
235 | dentry = d_alloc(NULL, &d_name); | |
236 | if (!dentry) { | |
237 | iput(root); | |
238 | goto Enomem; | |
239 | } | |
240 | dentry->d_sb = s; | |
241 | dentry->d_parent = dentry; | |
242 | d_instantiate(dentry, root); | |
243 | s->s_root = dentry; | |
244 | s->s_flags |= MS_ACTIVE; | |
a3ec947c SB |
245 | simple_set_mnt(mnt, s); |
246 | return 0; | |
1da177e4 LT |
247 | |
248 | Enomem: | |
249 | up_write(&s->s_umount); | |
250 | deactivate_super(s); | |
454e2398 | 251 | return -ENOMEM; |
1da177e4 LT |
252 | } |
253 | ||
254 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
255 | { | |
256 | struct inode *inode = old_dentry->d_inode; | |
257 | ||
258 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
d8c76e6f | 259 | inc_nlink(inode); |
1da177e4 LT |
260 | atomic_inc(&inode->i_count); |
261 | dget(dentry); | |
262 | d_instantiate(dentry, inode); | |
263 | return 0; | |
264 | } | |
265 | ||
266 | static inline int simple_positive(struct dentry *dentry) | |
267 | { | |
268 | return dentry->d_inode && !d_unhashed(dentry); | |
269 | } | |
270 | ||
271 | int simple_empty(struct dentry *dentry) | |
272 | { | |
273 | struct dentry *child; | |
274 | int ret = 0; | |
275 | ||
276 | spin_lock(&dcache_lock); | |
5160ee6f | 277 | list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) |
1da177e4 LT |
278 | if (simple_positive(child)) |
279 | goto out; | |
280 | ret = 1; | |
281 | out: | |
282 | spin_unlock(&dcache_lock); | |
283 | return ret; | |
284 | } | |
285 | ||
286 | int simple_unlink(struct inode *dir, struct dentry *dentry) | |
287 | { | |
288 | struct inode *inode = dentry->d_inode; | |
289 | ||
290 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
9a53c3a7 | 291 | drop_nlink(inode); |
1da177e4 LT |
292 | dput(dentry); |
293 | return 0; | |
294 | } | |
295 | ||
296 | int simple_rmdir(struct inode *dir, struct dentry *dentry) | |
297 | { | |
298 | if (!simple_empty(dentry)) | |
299 | return -ENOTEMPTY; | |
300 | ||
9a53c3a7 | 301 | drop_nlink(dentry->d_inode); |
1da177e4 | 302 | simple_unlink(dir, dentry); |
9a53c3a7 | 303 | drop_nlink(dir); |
1da177e4 LT |
304 | return 0; |
305 | } | |
306 | ||
307 | int simple_rename(struct inode *old_dir, struct dentry *old_dentry, | |
308 | struct inode *new_dir, struct dentry *new_dentry) | |
309 | { | |
310 | struct inode *inode = old_dentry->d_inode; | |
311 | int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); | |
312 | ||
313 | if (!simple_empty(new_dentry)) | |
314 | return -ENOTEMPTY; | |
315 | ||
316 | if (new_dentry->d_inode) { | |
317 | simple_unlink(new_dir, new_dentry); | |
318 | if (they_are_dirs) | |
9a53c3a7 | 319 | drop_nlink(old_dir); |
1da177e4 | 320 | } else if (they_are_dirs) { |
9a53c3a7 | 321 | drop_nlink(old_dir); |
d8c76e6f | 322 | inc_nlink(new_dir); |
1da177e4 LT |
323 | } |
324 | ||
325 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = | |
326 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; | |
327 | ||
328 | return 0; | |
329 | } | |
330 | ||
331 | int simple_readpage(struct file *file, struct page *page) | |
332 | { | |
c0d92cbc | 333 | clear_highpage(page); |
1da177e4 LT |
334 | flush_dcache_page(page); |
335 | SetPageUptodate(page); | |
1da177e4 LT |
336 | unlock_page(page); |
337 | return 0; | |
338 | } | |
339 | ||
340 | int simple_prepare_write(struct file *file, struct page *page, | |
341 | unsigned from, unsigned to) | |
342 | { | |
343 | if (!PageUptodate(page)) { | |
eebd2aa3 CL |
344 | if (to - from != PAGE_CACHE_SIZE) |
345 | zero_user_segments(page, | |
346 | 0, from, | |
347 | to, PAGE_CACHE_SIZE); | |
1da177e4 LT |
348 | } |
349 | return 0; | |
350 | } | |
351 | ||
afddba49 NP |
352 | int simple_write_begin(struct file *file, struct address_space *mapping, |
353 | loff_t pos, unsigned len, unsigned flags, | |
354 | struct page **pagep, void **fsdata) | |
355 | { | |
356 | struct page *page; | |
357 | pgoff_t index; | |
358 | unsigned from; | |
359 | ||
360 | index = pos >> PAGE_CACHE_SHIFT; | |
361 | from = pos & (PAGE_CACHE_SIZE - 1); | |
362 | ||
54566b2c | 363 | page = grab_cache_page_write_begin(mapping, index, flags); |
afddba49 NP |
364 | if (!page) |
365 | return -ENOMEM; | |
366 | ||
367 | *pagep = page; | |
368 | ||
369 | return simple_prepare_write(file, page, from, from+len); | |
370 | } | |
371 | ||
4a239427 AB |
372 | static int simple_commit_write(struct file *file, struct page *page, |
373 | unsigned from, unsigned to) | |
1da177e4 LT |
374 | { |
375 | struct inode *inode = page->mapping->host; | |
376 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
377 | ||
955eff5a NP |
378 | if (!PageUptodate(page)) |
379 | SetPageUptodate(page); | |
1da177e4 LT |
380 | /* |
381 | * No need to use i_size_read() here, the i_size | |
1b1dcc1b | 382 | * cannot change under us because we hold the i_mutex. |
1da177e4 LT |
383 | */ |
384 | if (pos > inode->i_size) | |
385 | i_size_write(inode, pos); | |
386 | set_page_dirty(page); | |
387 | return 0; | |
388 | } | |
389 | ||
afddba49 NP |
390 | int simple_write_end(struct file *file, struct address_space *mapping, |
391 | loff_t pos, unsigned len, unsigned copied, | |
392 | struct page *page, void *fsdata) | |
393 | { | |
394 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); | |
395 | ||
396 | /* zero the stale part of the page if we did a short copy */ | |
397 | if (copied < len) { | |
398 | void *kaddr = kmap_atomic(page, KM_USER0); | |
399 | memset(kaddr + from + copied, 0, len - copied); | |
400 | flush_dcache_page(page); | |
401 | kunmap_atomic(kaddr, KM_USER0); | |
402 | } | |
403 | ||
404 | simple_commit_write(file, page, from, from+copied); | |
405 | ||
406 | unlock_page(page); | |
407 | page_cache_release(page); | |
408 | ||
409 | return copied; | |
410 | } | |
411 | ||
1a1c9bb4 JL |
412 | /* |
413 | * the inodes created here are not hashed. If you use iunique to generate | |
414 | * unique inode values later for this filesystem, then you must take care | |
415 | * to pass it an appropriate max_reserved value to avoid collisions. | |
416 | */ | |
1da177e4 LT |
417 | int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files) |
418 | { | |
1da177e4 LT |
419 | struct inode *inode; |
420 | struct dentry *root; | |
421 | struct dentry *dentry; | |
422 | int i; | |
423 | ||
424 | s->s_blocksize = PAGE_CACHE_SIZE; | |
425 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
426 | s->s_magic = magic; | |
759b9775 | 427 | s->s_op = &simple_super_operations; |
1da177e4 LT |
428 | s->s_time_gran = 1; |
429 | ||
430 | inode = new_inode(s); | |
431 | if (!inode) | |
432 | return -ENOMEM; | |
1a1c9bb4 JL |
433 | /* |
434 | * because the root inode is 1, the files array must not contain an | |
435 | * entry at index 1 | |
436 | */ | |
437 | inode->i_ino = 1; | |
1da177e4 | 438 | inode->i_mode = S_IFDIR | 0755; |
1da177e4 LT |
439 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
440 | inode->i_op = &simple_dir_inode_operations; | |
441 | inode->i_fop = &simple_dir_operations; | |
7656f328 | 442 | inode->i_nlink = 2; |
1da177e4 LT |
443 | root = d_alloc_root(inode); |
444 | if (!root) { | |
445 | iput(inode); | |
446 | return -ENOMEM; | |
447 | } | |
448 | for (i = 0; !files->name || files->name[0]; i++, files++) { | |
449 | if (!files->name) | |
450 | continue; | |
1a1c9bb4 JL |
451 | |
452 | /* warn if it tries to conflict with the root inode */ | |
453 | if (unlikely(i == 1)) | |
454 | printk(KERN_WARNING "%s: %s passed in a files array" | |
455 | "with an index of 1!\n", __func__, | |
456 | s->s_type->name); | |
457 | ||
1da177e4 LT |
458 | dentry = d_alloc_name(root, files->name); |
459 | if (!dentry) | |
460 | goto out; | |
461 | inode = new_inode(s); | |
462 | if (!inode) | |
463 | goto out; | |
464 | inode->i_mode = S_IFREG | files->mode; | |
1da177e4 LT |
465 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
466 | inode->i_fop = files->ops; | |
467 | inode->i_ino = i; | |
468 | d_add(dentry, inode); | |
469 | } | |
470 | s->s_root = root; | |
471 | return 0; | |
472 | out: | |
473 | d_genocide(root); | |
474 | dput(root); | |
475 | return -ENOMEM; | |
476 | } | |
477 | ||
478 | static DEFINE_SPINLOCK(pin_fs_lock); | |
479 | ||
1f5ce9e9 | 480 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
1da177e4 LT |
481 | { |
482 | struct vfsmount *mnt = NULL; | |
483 | spin_lock(&pin_fs_lock); | |
484 | if (unlikely(!*mount)) { | |
485 | spin_unlock(&pin_fs_lock); | |
1f5ce9e9 | 486 | mnt = vfs_kern_mount(type, 0, type->name, NULL); |
1da177e4 LT |
487 | if (IS_ERR(mnt)) |
488 | return PTR_ERR(mnt); | |
489 | spin_lock(&pin_fs_lock); | |
490 | if (!*mount) | |
491 | *mount = mnt; | |
492 | } | |
493 | mntget(*mount); | |
494 | ++*count; | |
495 | spin_unlock(&pin_fs_lock); | |
496 | mntput(mnt); | |
497 | return 0; | |
498 | } | |
499 | ||
500 | void simple_release_fs(struct vfsmount **mount, int *count) | |
501 | { | |
502 | struct vfsmount *mnt; | |
503 | spin_lock(&pin_fs_lock); | |
504 | mnt = *mount; | |
505 | if (!--*count) | |
506 | *mount = NULL; | |
507 | spin_unlock(&pin_fs_lock); | |
508 | mntput(mnt); | |
509 | } | |
510 | ||
6d1029b5 AM |
511 | /** |
512 | * simple_read_from_buffer - copy data from the buffer to user space | |
513 | * @to: the user space buffer to read to | |
514 | * @count: the maximum number of bytes to read | |
515 | * @ppos: the current position in the buffer | |
516 | * @from: the buffer to read from | |
517 | * @available: the size of the buffer | |
518 | * | |
519 | * The simple_read_from_buffer() function reads up to @count bytes from the | |
520 | * buffer @from at offset @ppos into the user space address starting at @to. | |
521 | * | |
522 | * On success, the number of bytes read is returned and the offset @ppos is | |
523 | * advanced by this number, or negative value is returned on error. | |
524 | **/ | |
1da177e4 LT |
525 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
526 | const void *from, size_t available) | |
527 | { | |
528 | loff_t pos = *ppos; | |
529 | if (pos < 0) | |
530 | return -EINVAL; | |
531 | if (pos >= available) | |
532 | return 0; | |
533 | if (count > available - pos) | |
534 | count = available - pos; | |
535 | if (copy_to_user(to, from + pos, count)) | |
536 | return -EFAULT; | |
537 | *ppos = pos + count; | |
538 | return count; | |
539 | } | |
540 | ||
6d1029b5 AM |
541 | /** |
542 | * memory_read_from_buffer - copy data from the buffer | |
543 | * @to: the kernel space buffer to read to | |
544 | * @count: the maximum number of bytes to read | |
545 | * @ppos: the current position in the buffer | |
546 | * @from: the buffer to read from | |
547 | * @available: the size of the buffer | |
548 | * | |
549 | * The memory_read_from_buffer() function reads up to @count bytes from the | |
550 | * buffer @from at offset @ppos into the kernel space address starting at @to. | |
551 | * | |
552 | * On success, the number of bytes read is returned and the offset @ppos is | |
553 | * advanced by this number, or negative value is returned on error. | |
554 | **/ | |
93b07113 AM |
555 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
556 | const void *from, size_t available) | |
557 | { | |
558 | loff_t pos = *ppos; | |
559 | ||
560 | if (pos < 0) | |
561 | return -EINVAL; | |
562 | if (pos >= available) | |
563 | return 0; | |
564 | if (count > available - pos) | |
565 | count = available - pos; | |
566 | memcpy(to, from + pos, count); | |
567 | *ppos = pos + count; | |
568 | ||
569 | return count; | |
570 | } | |
571 | ||
1da177e4 LT |
572 | /* |
573 | * Transaction based IO. | |
574 | * The file expects a single write which triggers the transaction, and then | |
575 | * possibly a read which collects the result - which is stored in a | |
576 | * file-local buffer. | |
577 | */ | |
578 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) | |
579 | { | |
580 | struct simple_transaction_argresp *ar; | |
581 | static DEFINE_SPINLOCK(simple_transaction_lock); | |
582 | ||
583 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) | |
584 | return ERR_PTR(-EFBIG); | |
585 | ||
586 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); | |
587 | if (!ar) | |
588 | return ERR_PTR(-ENOMEM); | |
589 | ||
590 | spin_lock(&simple_transaction_lock); | |
591 | ||
592 | /* only one write allowed per open */ | |
593 | if (file->private_data) { | |
594 | spin_unlock(&simple_transaction_lock); | |
595 | free_page((unsigned long)ar); | |
596 | return ERR_PTR(-EBUSY); | |
597 | } | |
598 | ||
599 | file->private_data = ar; | |
600 | ||
601 | spin_unlock(&simple_transaction_lock); | |
602 | ||
603 | if (copy_from_user(ar->data, buf, size)) | |
604 | return ERR_PTR(-EFAULT); | |
605 | ||
606 | return ar->data; | |
607 | } | |
608 | ||
609 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) | |
610 | { | |
611 | struct simple_transaction_argresp *ar = file->private_data; | |
612 | ||
613 | if (!ar) | |
614 | return 0; | |
615 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); | |
616 | } | |
617 | ||
618 | int simple_transaction_release(struct inode *inode, struct file *file) | |
619 | { | |
620 | free_page((unsigned long)file->private_data); | |
621 | return 0; | |
622 | } | |
623 | ||
acaefc25 AB |
624 | /* Simple attribute files */ |
625 | ||
626 | struct simple_attr { | |
8b88b099 CH |
627 | int (*get)(void *, u64 *); |
628 | int (*set)(void *, u64); | |
acaefc25 AB |
629 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
630 | char set_buf[24]; | |
631 | void *data; | |
632 | const char *fmt; /* format for read operation */ | |
7cf34c76 | 633 | struct mutex mutex; /* protects access to these buffers */ |
acaefc25 AB |
634 | }; |
635 | ||
636 | /* simple_attr_open is called by an actual attribute open file operation | |
637 | * to set the attribute specific access operations. */ | |
638 | int simple_attr_open(struct inode *inode, struct file *file, | |
8b88b099 | 639 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
acaefc25 AB |
640 | const char *fmt) |
641 | { | |
642 | struct simple_attr *attr; | |
643 | ||
644 | attr = kmalloc(sizeof(*attr), GFP_KERNEL); | |
645 | if (!attr) | |
646 | return -ENOMEM; | |
647 | ||
648 | attr->get = get; | |
649 | attr->set = set; | |
8e18e294 | 650 | attr->data = inode->i_private; |
acaefc25 | 651 | attr->fmt = fmt; |
7cf34c76 | 652 | mutex_init(&attr->mutex); |
acaefc25 AB |
653 | |
654 | file->private_data = attr; | |
655 | ||
656 | return nonseekable_open(inode, file); | |
657 | } | |
658 | ||
74bedc4d | 659 | int simple_attr_release(struct inode *inode, struct file *file) |
acaefc25 AB |
660 | { |
661 | kfree(file->private_data); | |
662 | return 0; | |
663 | } | |
664 | ||
665 | /* read from the buffer that is filled with the get function */ | |
666 | ssize_t simple_attr_read(struct file *file, char __user *buf, | |
667 | size_t len, loff_t *ppos) | |
668 | { | |
669 | struct simple_attr *attr; | |
670 | size_t size; | |
671 | ssize_t ret; | |
672 | ||
673 | attr = file->private_data; | |
674 | ||
675 | if (!attr->get) | |
676 | return -EACCES; | |
677 | ||
9261303a CH |
678 | ret = mutex_lock_interruptible(&attr->mutex); |
679 | if (ret) | |
680 | return ret; | |
681 | ||
8b88b099 | 682 | if (*ppos) { /* continued read */ |
acaefc25 | 683 | size = strlen(attr->get_buf); |
8b88b099 CH |
684 | } else { /* first read */ |
685 | u64 val; | |
686 | ret = attr->get(attr->data, &val); | |
687 | if (ret) | |
688 | goto out; | |
689 | ||
acaefc25 | 690 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
8b88b099 CH |
691 | attr->fmt, (unsigned long long)val); |
692 | } | |
acaefc25 AB |
693 | |
694 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); | |
8b88b099 | 695 | out: |
7cf34c76 | 696 | mutex_unlock(&attr->mutex); |
acaefc25 AB |
697 | return ret; |
698 | } | |
699 | ||
700 | /* interpret the buffer as a number to call the set function with */ | |
701 | ssize_t simple_attr_write(struct file *file, const char __user *buf, | |
702 | size_t len, loff_t *ppos) | |
703 | { | |
704 | struct simple_attr *attr; | |
705 | u64 val; | |
706 | size_t size; | |
707 | ssize_t ret; | |
708 | ||
709 | attr = file->private_data; | |
acaefc25 AB |
710 | if (!attr->set) |
711 | return -EACCES; | |
712 | ||
9261303a CH |
713 | ret = mutex_lock_interruptible(&attr->mutex); |
714 | if (ret) | |
715 | return ret; | |
716 | ||
acaefc25 AB |
717 | ret = -EFAULT; |
718 | size = min(sizeof(attr->set_buf) - 1, len); | |
719 | if (copy_from_user(attr->set_buf, buf, size)) | |
720 | goto out; | |
721 | ||
722 | ret = len; /* claim we got the whole input */ | |
723 | attr->set_buf[size] = '\0'; | |
724 | val = simple_strtol(attr->set_buf, NULL, 0); | |
725 | attr->set(attr->data, val); | |
726 | out: | |
7cf34c76 | 727 | mutex_unlock(&attr->mutex); |
acaefc25 AB |
728 | return ret; |
729 | } | |
730 | ||
2596110a CH |
731 | /** |
732 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation | |
733 | * @sb: filesystem to do the file handle conversion on | |
734 | * @fid: file handle to convert | |
735 | * @fh_len: length of the file handle in bytes | |
736 | * @fh_type: type of file handle | |
737 | * @get_inode: filesystem callback to retrieve inode | |
738 | * | |
739 | * This function decodes @fid as long as it has one of the well-known | |
740 | * Linux filehandle types and calls @get_inode on it to retrieve the | |
741 | * inode for the object specified in the file handle. | |
742 | */ | |
743 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, | |
744 | int fh_len, int fh_type, struct inode *(*get_inode) | |
745 | (struct super_block *sb, u64 ino, u32 gen)) | |
746 | { | |
747 | struct inode *inode = NULL; | |
748 | ||
749 | if (fh_len < 2) | |
750 | return NULL; | |
751 | ||
752 | switch (fh_type) { | |
753 | case FILEID_INO32_GEN: | |
754 | case FILEID_INO32_GEN_PARENT: | |
755 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); | |
756 | break; | |
757 | } | |
758 | ||
4ea3ada2 | 759 | return d_obtain_alias(inode); |
2596110a CH |
760 | } |
761 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); | |
762 | ||
763 | /** | |
764 | * generic_fh_to_dentry - generic helper for the fh_to_parent export operation | |
765 | * @sb: filesystem to do the file handle conversion on | |
766 | * @fid: file handle to convert | |
767 | * @fh_len: length of the file handle in bytes | |
768 | * @fh_type: type of file handle | |
769 | * @get_inode: filesystem callback to retrieve inode | |
770 | * | |
771 | * This function decodes @fid as long as it has one of the well-known | |
772 | * Linux filehandle types and calls @get_inode on it to retrieve the | |
773 | * inode for the _parent_ object specified in the file handle if it | |
774 | * is specified in the file handle, or NULL otherwise. | |
775 | */ | |
776 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, | |
777 | int fh_len, int fh_type, struct inode *(*get_inode) | |
778 | (struct super_block *sb, u64 ino, u32 gen)) | |
779 | { | |
780 | struct inode *inode = NULL; | |
781 | ||
782 | if (fh_len <= 2) | |
783 | return NULL; | |
784 | ||
785 | switch (fh_type) { | |
786 | case FILEID_INO32_GEN_PARENT: | |
787 | inode = get_inode(sb, fid->i32.parent_ino, | |
788 | (fh_len > 3 ? fid->i32.parent_gen : 0)); | |
789 | break; | |
790 | } | |
791 | ||
4ea3ada2 | 792 | return d_obtain_alias(inode); |
2596110a CH |
793 | } |
794 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); | |
795 | ||
1da177e4 LT |
796 | EXPORT_SYMBOL(dcache_dir_close); |
797 | EXPORT_SYMBOL(dcache_dir_lseek); | |
798 | EXPORT_SYMBOL(dcache_dir_open); | |
799 | EXPORT_SYMBOL(dcache_readdir); | |
800 | EXPORT_SYMBOL(generic_read_dir); | |
801 | EXPORT_SYMBOL(get_sb_pseudo); | |
afddba49 NP |
802 | EXPORT_SYMBOL(simple_write_begin); |
803 | EXPORT_SYMBOL(simple_write_end); | |
1da177e4 LT |
804 | EXPORT_SYMBOL(simple_dir_inode_operations); |
805 | EXPORT_SYMBOL(simple_dir_operations); | |
806 | EXPORT_SYMBOL(simple_empty); | |
807 | EXPORT_SYMBOL(d_alloc_name); | |
808 | EXPORT_SYMBOL(simple_fill_super); | |
809 | EXPORT_SYMBOL(simple_getattr); | |
810 | EXPORT_SYMBOL(simple_link); | |
811 | EXPORT_SYMBOL(simple_lookup); | |
812 | EXPORT_SYMBOL(simple_pin_fs); | |
4e02ed4b | 813 | EXPORT_UNUSED_SYMBOL(simple_prepare_write); |
1da177e4 LT |
814 | EXPORT_SYMBOL(simple_readpage); |
815 | EXPORT_SYMBOL(simple_release_fs); | |
816 | EXPORT_SYMBOL(simple_rename); | |
817 | EXPORT_SYMBOL(simple_rmdir); | |
818 | EXPORT_SYMBOL(simple_statfs); | |
819 | EXPORT_SYMBOL(simple_sync_file); | |
820 | EXPORT_SYMBOL(simple_unlink); | |
821 | EXPORT_SYMBOL(simple_read_from_buffer); | |
93b07113 | 822 | EXPORT_SYMBOL(memory_read_from_buffer); |
1da177e4 LT |
823 | EXPORT_SYMBOL(simple_transaction_get); |
824 | EXPORT_SYMBOL(simple_transaction_read); | |
825 | EXPORT_SYMBOL(simple_transaction_release); | |
acaefc25 | 826 | EXPORT_SYMBOL_GPL(simple_attr_open); |
74bedc4d | 827 | EXPORT_SYMBOL_GPL(simple_attr_release); |
acaefc25 AB |
828 | EXPORT_SYMBOL_GPL(simple_attr_read); |
829 | EXPORT_SYMBOL_GPL(simple_attr_write); |