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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> | |
5a0e3ad6 | 8 | #include <linux/slab.h> |
1da177e4 LT |
9 | #include <linux/mount.h> |
10 | #include <linux/vfs.h> | |
7cf34c76 | 11 | #include <linux/mutex.h> |
2596110a | 12 | #include <linux/exportfs.h> |
d5aacad5 AV |
13 | #include <linux/writeback.h> |
14 | #include <linux/buffer_head.h> | |
7cf34c76 | 15 | |
1da177e4 LT |
16 | #include <asm/uaccess.h> |
17 | ||
18 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
19 | struct kstat *stat) | |
20 | { | |
21 | struct inode *inode = dentry->d_inode; | |
22 | generic_fillattr(inode, stat); | |
23 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); | |
24 | return 0; | |
25 | } | |
26 | ||
726c3342 | 27 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
1da177e4 | 28 | { |
726c3342 | 29 | buf->f_type = dentry->d_sb->s_magic; |
1da177e4 LT |
30 | buf->f_bsize = PAGE_CACHE_SIZE; |
31 | buf->f_namelen = NAME_MAX; | |
32 | return 0; | |
33 | } | |
34 | ||
35 | /* | |
36 | * Retaining negative dentries for an in-memory filesystem just wastes | |
37 | * memory and lookup time: arrange for them to be deleted immediately. | |
38 | */ | |
39 | static int simple_delete_dentry(struct dentry *dentry) | |
40 | { | |
41 | return 1; | |
42 | } | |
43 | ||
44 | /* | |
45 | * Lookup the data. This is trivial - if the dentry didn't already | |
46 | * exist, we know it is negative. Set d_op to delete negative dentries. | |
47 | */ | |
48 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) | |
49 | { | |
3ba13d17 | 50 | static const struct dentry_operations simple_dentry_operations = { |
1da177e4 LT |
51 | .d_delete = simple_delete_dentry, |
52 | }; | |
53 | ||
54 | if (dentry->d_name.len > NAME_MAX) | |
55 | return ERR_PTR(-ENAMETOOLONG); | |
56 | dentry->d_op = &simple_dentry_operations; | |
57 | d_add(dentry, NULL); | |
58 | return NULL; | |
59 | } | |
60 | ||
1da177e4 LT |
61 | int dcache_dir_open(struct inode *inode, struct file *file) |
62 | { | |
63 | static struct qstr cursor_name = {.len = 1, .name = "."}; | |
64 | ||
0f7fc9e4 | 65 | file->private_data = d_alloc(file->f_path.dentry, &cursor_name); |
1da177e4 LT |
66 | |
67 | return file->private_data ? 0 : -ENOMEM; | |
68 | } | |
69 | ||
70 | int dcache_dir_close(struct inode *inode, struct file *file) | |
71 | { | |
72 | dput(file->private_data); | |
73 | return 0; | |
74 | } | |
75 | ||
76 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) | |
77 | { | |
0f7fc9e4 | 78 | mutex_lock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
79 | switch (origin) { |
80 | case 1: | |
81 | offset += file->f_pos; | |
82 | case 0: | |
83 | if (offset >= 0) | |
84 | break; | |
85 | default: | |
0f7fc9e4 | 86 | mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
87 | return -EINVAL; |
88 | } | |
89 | if (offset != file->f_pos) { | |
90 | file->f_pos = offset; | |
91 | if (file->f_pos >= 2) { | |
92 | struct list_head *p; | |
93 | struct dentry *cursor = file->private_data; | |
94 | loff_t n = file->f_pos - 2; | |
95 | ||
96 | spin_lock(&dcache_lock); | |
5160ee6f | 97 | list_del(&cursor->d_u.d_child); |
0f7fc9e4 JJS |
98 | p = file->f_path.dentry->d_subdirs.next; |
99 | while (n && p != &file->f_path.dentry->d_subdirs) { | |
1da177e4 | 100 | struct dentry *next; |
5160ee6f | 101 | next = list_entry(p, struct dentry, d_u.d_child); |
1da177e4 LT |
102 | if (!d_unhashed(next) && next->d_inode) |
103 | n--; | |
104 | p = p->next; | |
105 | } | |
5160ee6f | 106 | list_add_tail(&cursor->d_u.d_child, p); |
1da177e4 LT |
107 | spin_unlock(&dcache_lock); |
108 | } | |
109 | } | |
0f7fc9e4 | 110 | mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
111 | return offset; |
112 | } | |
113 | ||
114 | /* Relationship between i_mode and the DT_xxx types */ | |
115 | static inline unsigned char dt_type(struct inode *inode) | |
116 | { | |
117 | return (inode->i_mode >> 12) & 15; | |
118 | } | |
119 | ||
120 | /* | |
121 | * Directory is locked and all positive dentries in it are safe, since | |
122 | * for ramfs-type trees they can't go away without unlink() or rmdir(), | |
123 | * both impossible due to the lock on directory. | |
124 | */ | |
125 | ||
126 | int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) | |
127 | { | |
0f7fc9e4 | 128 | struct dentry *dentry = filp->f_path.dentry; |
1da177e4 | 129 | struct dentry *cursor = filp->private_data; |
5160ee6f | 130 | struct list_head *p, *q = &cursor->d_u.d_child; |
1da177e4 LT |
131 | ino_t ino; |
132 | int i = filp->f_pos; | |
133 | ||
134 | switch (i) { | |
135 | case 0: | |
136 | ino = dentry->d_inode->i_ino; | |
137 | if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) | |
138 | break; | |
139 | filp->f_pos++; | |
140 | i++; | |
141 | /* fallthrough */ | |
142 | case 1: | |
143 | ino = parent_ino(dentry); | |
144 | if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) | |
145 | break; | |
146 | filp->f_pos++; | |
147 | i++; | |
148 | /* fallthrough */ | |
149 | default: | |
150 | spin_lock(&dcache_lock); | |
1bfba4e8 AM |
151 | if (filp->f_pos == 2) |
152 | list_move(q, &dentry->d_subdirs); | |
153 | ||
1da177e4 LT |
154 | for (p=q->next; p != &dentry->d_subdirs; p=p->next) { |
155 | struct dentry *next; | |
5160ee6f | 156 | next = list_entry(p, struct dentry, d_u.d_child); |
1da177e4 LT |
157 | if (d_unhashed(next) || !next->d_inode) |
158 | continue; | |
159 | ||
160 | spin_unlock(&dcache_lock); | |
0f8952c2 RN |
161 | if (filldir(dirent, next->d_name.name, |
162 | next->d_name.len, filp->f_pos, | |
163 | next->d_inode->i_ino, | |
164 | dt_type(next->d_inode)) < 0) | |
1da177e4 LT |
165 | return 0; |
166 | spin_lock(&dcache_lock); | |
167 | /* next is still alive */ | |
1bfba4e8 | 168 | list_move(q, p); |
1da177e4 LT |
169 | p = q; |
170 | filp->f_pos++; | |
171 | } | |
172 | spin_unlock(&dcache_lock); | |
173 | } | |
174 | return 0; | |
175 | } | |
176 | ||
177 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) | |
178 | { | |
179 | return -EISDIR; | |
180 | } | |
181 | ||
4b6f5d20 | 182 | const struct file_operations simple_dir_operations = { |
1da177e4 LT |
183 | .open = dcache_dir_open, |
184 | .release = dcache_dir_close, | |
185 | .llseek = dcache_dir_lseek, | |
186 | .read = generic_read_dir, | |
187 | .readdir = dcache_readdir, | |
1b061d92 | 188 | .fsync = noop_fsync, |
1da177e4 LT |
189 | }; |
190 | ||
92e1d5be | 191 | const struct inode_operations simple_dir_inode_operations = { |
1da177e4 LT |
192 | .lookup = simple_lookup, |
193 | }; | |
194 | ||
759b9775 HD |
195 | static const struct super_operations simple_super_operations = { |
196 | .statfs = simple_statfs, | |
197 | }; | |
198 | ||
1da177e4 LT |
199 | /* |
200 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that | |
201 | * will never be mountable) | |
202 | */ | |
454e2398 | 203 | int get_sb_pseudo(struct file_system_type *fs_type, char *name, |
ee9b6d61 | 204 | const struct super_operations *ops, unsigned long magic, |
454e2398 | 205 | struct vfsmount *mnt) |
1da177e4 LT |
206 | { |
207 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
1da177e4 LT |
208 | struct dentry *dentry; |
209 | struct inode *root; | |
210 | struct qstr d_name = {.name = name, .len = strlen(name)}; | |
211 | ||
212 | if (IS_ERR(s)) | |
454e2398 | 213 | return PTR_ERR(s); |
1da177e4 LT |
214 | |
215 | s->s_flags = MS_NOUSER; | |
89a4eb4b | 216 | s->s_maxbytes = MAX_LFS_FILESIZE; |
3971e1a9 AN |
217 | s->s_blocksize = PAGE_SIZE; |
218 | s->s_blocksize_bits = PAGE_SHIFT; | |
1da177e4 | 219 | s->s_magic = magic; |
759b9775 | 220 | s->s_op = ops ? ops : &simple_super_operations; |
1da177e4 LT |
221 | s->s_time_gran = 1; |
222 | root = new_inode(s); | |
223 | if (!root) | |
224 | goto Enomem; | |
1a1c9bb4 JL |
225 | /* |
226 | * since this is the first inode, make it number 1. New inodes created | |
227 | * after this must take care not to collide with it (by passing | |
228 | * max_reserved of 1 to iunique). | |
229 | */ | |
230 | root->i_ino = 1; | |
1da177e4 | 231 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
1da177e4 LT |
232 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; |
233 | dentry = d_alloc(NULL, &d_name); | |
234 | if (!dentry) { | |
235 | iput(root); | |
236 | goto Enomem; | |
237 | } | |
238 | dentry->d_sb = s; | |
239 | dentry->d_parent = dentry; | |
240 | d_instantiate(dentry, root); | |
241 | s->s_root = dentry; | |
242 | s->s_flags |= MS_ACTIVE; | |
a3ec947c SB |
243 | simple_set_mnt(mnt, s); |
244 | return 0; | |
1da177e4 LT |
245 | |
246 | Enomem: | |
6f5bbff9 | 247 | deactivate_locked_super(s); |
454e2398 | 248 | return -ENOMEM; |
1da177e4 LT |
249 | } |
250 | ||
251 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
252 | { | |
253 | struct inode *inode = old_dentry->d_inode; | |
254 | ||
255 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
d8c76e6f | 256 | inc_nlink(inode); |
1da177e4 LT |
257 | atomic_inc(&inode->i_count); |
258 | dget(dentry); | |
259 | d_instantiate(dentry, inode); | |
260 | return 0; | |
261 | } | |
262 | ||
263 | static inline int simple_positive(struct dentry *dentry) | |
264 | { | |
265 | return dentry->d_inode && !d_unhashed(dentry); | |
266 | } | |
267 | ||
268 | int simple_empty(struct dentry *dentry) | |
269 | { | |
270 | struct dentry *child; | |
271 | int ret = 0; | |
272 | ||
273 | spin_lock(&dcache_lock); | |
5160ee6f | 274 | list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) |
1da177e4 LT |
275 | if (simple_positive(child)) |
276 | goto out; | |
277 | ret = 1; | |
278 | out: | |
279 | spin_unlock(&dcache_lock); | |
280 | return ret; | |
281 | } | |
282 | ||
283 | int simple_unlink(struct inode *dir, struct dentry *dentry) | |
284 | { | |
285 | struct inode *inode = dentry->d_inode; | |
286 | ||
287 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
9a53c3a7 | 288 | drop_nlink(inode); |
1da177e4 LT |
289 | dput(dentry); |
290 | return 0; | |
291 | } | |
292 | ||
293 | int simple_rmdir(struct inode *dir, struct dentry *dentry) | |
294 | { | |
295 | if (!simple_empty(dentry)) | |
296 | return -ENOTEMPTY; | |
297 | ||
9a53c3a7 | 298 | drop_nlink(dentry->d_inode); |
1da177e4 | 299 | simple_unlink(dir, dentry); |
9a53c3a7 | 300 | drop_nlink(dir); |
1da177e4 LT |
301 | return 0; |
302 | } | |
303 | ||
304 | int simple_rename(struct inode *old_dir, struct dentry *old_dentry, | |
305 | struct inode *new_dir, struct dentry *new_dentry) | |
306 | { | |
307 | struct inode *inode = old_dentry->d_inode; | |
308 | int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); | |
309 | ||
310 | if (!simple_empty(new_dentry)) | |
311 | return -ENOTEMPTY; | |
312 | ||
313 | if (new_dentry->d_inode) { | |
314 | simple_unlink(new_dir, new_dentry); | |
315 | if (they_are_dirs) | |
9a53c3a7 | 316 | drop_nlink(old_dir); |
1da177e4 | 317 | } else if (they_are_dirs) { |
9a53c3a7 | 318 | drop_nlink(old_dir); |
d8c76e6f | 319 | inc_nlink(new_dir); |
1da177e4 LT |
320 | } |
321 | ||
322 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = | |
323 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; | |
324 | ||
325 | return 0; | |
326 | } | |
327 | ||
328 | int simple_readpage(struct file *file, struct page *page) | |
329 | { | |
c0d92cbc | 330 | clear_highpage(page); |
1da177e4 LT |
331 | flush_dcache_page(page); |
332 | SetPageUptodate(page); | |
1da177e4 LT |
333 | unlock_page(page); |
334 | return 0; | |
335 | } | |
336 | ||
afddba49 NP |
337 | int simple_write_begin(struct file *file, struct address_space *mapping, |
338 | loff_t pos, unsigned len, unsigned flags, | |
339 | struct page **pagep, void **fsdata) | |
340 | { | |
341 | struct page *page; | |
342 | pgoff_t index; | |
afddba49 NP |
343 | |
344 | index = pos >> PAGE_CACHE_SHIFT; | |
afddba49 | 345 | |
54566b2c | 346 | page = grab_cache_page_write_begin(mapping, index, flags); |
afddba49 NP |
347 | if (!page) |
348 | return -ENOMEM; | |
349 | ||
350 | *pagep = page; | |
351 | ||
193cf4b9 BH |
352 | if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { |
353 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); | |
354 | ||
355 | zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); | |
356 | } | |
357 | return 0; | |
afddba49 NP |
358 | } |
359 | ||
ad2a722f BH |
360 | /** |
361 | * simple_write_end - .write_end helper for non-block-device FSes | |
362 | * @available: See .write_end of address_space_operations | |
363 | * @file: " | |
364 | * @mapping: " | |
365 | * @pos: " | |
366 | * @len: " | |
367 | * @copied: " | |
368 | * @page: " | |
369 | * @fsdata: " | |
370 | * | |
371 | * simple_write_end does the minimum needed for updating a page after writing is | |
372 | * done. It has the same API signature as the .write_end of | |
373 | * address_space_operations vector. So it can just be set onto .write_end for | |
374 | * FSes that don't need any other processing. i_mutex is assumed to be held. | |
375 | * Block based filesystems should use generic_write_end(). | |
376 | * NOTE: Even though i_size might get updated by this function, mark_inode_dirty | |
377 | * is not called, so a filesystem that actually does store data in .write_inode | |
378 | * should extend on what's done here with a call to mark_inode_dirty() in the | |
379 | * case that i_size has changed. | |
380 | */ | |
afddba49 NP |
381 | int simple_write_end(struct file *file, struct address_space *mapping, |
382 | loff_t pos, unsigned len, unsigned copied, | |
383 | struct page *page, void *fsdata) | |
384 | { | |
ad2a722f BH |
385 | struct inode *inode = page->mapping->host; |
386 | loff_t last_pos = pos + copied; | |
afddba49 NP |
387 | |
388 | /* zero the stale part of the page if we did a short copy */ | |
389 | if (copied < len) { | |
ad2a722f BH |
390 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
391 | ||
392 | zero_user(page, from + copied, len - copied); | |
afddba49 NP |
393 | } |
394 | ||
ad2a722f BH |
395 | if (!PageUptodate(page)) |
396 | SetPageUptodate(page); | |
397 | /* | |
398 | * No need to use i_size_read() here, the i_size | |
399 | * cannot change under us because we hold the i_mutex. | |
400 | */ | |
401 | if (last_pos > inode->i_size) | |
402 | i_size_write(inode, last_pos); | |
afddba49 | 403 | |
ad2a722f | 404 | set_page_dirty(page); |
afddba49 NP |
405 | unlock_page(page); |
406 | page_cache_release(page); | |
407 | ||
408 | return copied; | |
409 | } | |
410 | ||
1a1c9bb4 JL |
411 | /* |
412 | * the inodes created here are not hashed. If you use iunique to generate | |
413 | * unique inode values later for this filesystem, then you must take care | |
414 | * to pass it an appropriate max_reserved value to avoid collisions. | |
415 | */ | |
1da177e4 LT |
416 | int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files) |
417 | { | |
1da177e4 LT |
418 | struct inode *inode; |
419 | struct dentry *root; | |
420 | struct dentry *dentry; | |
421 | int i; | |
422 | ||
423 | s->s_blocksize = PAGE_CACHE_SIZE; | |
424 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
425 | s->s_magic = magic; | |
759b9775 | 426 | s->s_op = &simple_super_operations; |
1da177e4 LT |
427 | s->s_time_gran = 1; |
428 | ||
429 | inode = new_inode(s); | |
430 | if (!inode) | |
431 | return -ENOMEM; | |
1a1c9bb4 JL |
432 | /* |
433 | * because the root inode is 1, the files array must not contain an | |
434 | * entry at index 1 | |
435 | */ | |
436 | inode->i_ino = 1; | |
1da177e4 | 437 | inode->i_mode = S_IFDIR | 0755; |
1da177e4 LT |
438 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
439 | inode->i_op = &simple_dir_inode_operations; | |
440 | inode->i_fop = &simple_dir_operations; | |
7656f328 | 441 | inode->i_nlink = 2; |
1da177e4 LT |
442 | root = d_alloc_root(inode); |
443 | if (!root) { | |
444 | iput(inode); | |
445 | return -ENOMEM; | |
446 | } | |
447 | for (i = 0; !files->name || files->name[0]; i++, files++) { | |
448 | if (!files->name) | |
449 | continue; | |
1a1c9bb4 JL |
450 | |
451 | /* warn if it tries to conflict with the root inode */ | |
452 | if (unlikely(i == 1)) | |
453 | printk(KERN_WARNING "%s: %s passed in a files array" | |
454 | "with an index of 1!\n", __func__, | |
455 | s->s_type->name); | |
456 | ||
1da177e4 LT |
457 | dentry = d_alloc_name(root, files->name); |
458 | if (!dentry) | |
459 | goto out; | |
460 | inode = new_inode(s); | |
461 | if (!inode) | |
462 | goto out; | |
463 | inode->i_mode = S_IFREG | files->mode; | |
1da177e4 LT |
464 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
465 | inode->i_fop = files->ops; | |
466 | inode->i_ino = i; | |
467 | d_add(dentry, inode); | |
468 | } | |
469 | s->s_root = root; | |
470 | return 0; | |
471 | out: | |
472 | d_genocide(root); | |
473 | dput(root); | |
474 | return -ENOMEM; | |
475 | } | |
476 | ||
477 | static DEFINE_SPINLOCK(pin_fs_lock); | |
478 | ||
1f5ce9e9 | 479 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
1da177e4 LT |
480 | { |
481 | struct vfsmount *mnt = NULL; | |
482 | spin_lock(&pin_fs_lock); | |
483 | if (unlikely(!*mount)) { | |
484 | spin_unlock(&pin_fs_lock); | |
1f5ce9e9 | 485 | mnt = vfs_kern_mount(type, 0, type->name, NULL); |
1da177e4 LT |
486 | if (IS_ERR(mnt)) |
487 | return PTR_ERR(mnt); | |
488 | spin_lock(&pin_fs_lock); | |
489 | if (!*mount) | |
490 | *mount = mnt; | |
491 | } | |
492 | mntget(*mount); | |
493 | ++*count; | |
494 | spin_unlock(&pin_fs_lock); | |
495 | mntput(mnt); | |
496 | return 0; | |
497 | } | |
498 | ||
499 | void simple_release_fs(struct vfsmount **mount, int *count) | |
500 | { | |
501 | struct vfsmount *mnt; | |
502 | spin_lock(&pin_fs_lock); | |
503 | mnt = *mount; | |
504 | if (!--*count) | |
505 | *mount = NULL; | |
506 | spin_unlock(&pin_fs_lock); | |
507 | mntput(mnt); | |
508 | } | |
509 | ||
6d1029b5 AM |
510 | /** |
511 | * simple_read_from_buffer - copy data from the buffer to user space | |
512 | * @to: the user space buffer to read to | |
513 | * @count: the maximum number of bytes to read | |
514 | * @ppos: the current position in the buffer | |
515 | * @from: the buffer to read from | |
516 | * @available: the size of the buffer | |
517 | * | |
518 | * The simple_read_from_buffer() function reads up to @count bytes from the | |
519 | * buffer @from at offset @ppos into the user space address starting at @to. | |
520 | * | |
521 | * On success, the number of bytes read is returned and the offset @ppos is | |
522 | * advanced by this number, or negative value is returned on error. | |
523 | **/ | |
1da177e4 LT |
524 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
525 | const void *from, size_t available) | |
526 | { | |
527 | loff_t pos = *ppos; | |
14be2746 SR |
528 | size_t ret; |
529 | ||
1da177e4 LT |
530 | if (pos < 0) |
531 | return -EINVAL; | |
14be2746 | 532 | if (pos >= available || !count) |
1da177e4 LT |
533 | return 0; |
534 | if (count > available - pos) | |
535 | count = available - pos; | |
14be2746 SR |
536 | ret = copy_to_user(to, from + pos, count); |
537 | if (ret == count) | |
1da177e4 | 538 | return -EFAULT; |
14be2746 | 539 | count -= ret; |
1da177e4 LT |
540 | *ppos = pos + count; |
541 | return count; | |
542 | } | |
543 | ||
6a727b43 JS |
544 | /** |
545 | * simple_write_to_buffer - copy data from user space to the buffer | |
546 | * @to: the buffer to write to | |
547 | * @available: the size of the buffer | |
548 | * @ppos: the current position in the buffer | |
549 | * @from: the user space buffer to read from | |
550 | * @count: the maximum number of bytes to read | |
551 | * | |
552 | * The simple_write_to_buffer() function reads up to @count bytes from the user | |
553 | * space address starting at @from into the buffer @to at offset @ppos. | |
554 | * | |
555 | * On success, the number of bytes written is returned and the offset @ppos is | |
556 | * advanced by this number, or negative value is returned on error. | |
557 | **/ | |
558 | ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, | |
559 | const void __user *from, size_t count) | |
560 | { | |
561 | loff_t pos = *ppos; | |
562 | size_t res; | |
563 | ||
564 | if (pos < 0) | |
565 | return -EINVAL; | |
566 | if (pos >= available || !count) | |
567 | return 0; | |
568 | if (count > available - pos) | |
569 | count = available - pos; | |
570 | res = copy_from_user(to + pos, from, count); | |
571 | if (res == count) | |
572 | return -EFAULT; | |
573 | count -= res; | |
574 | *ppos = pos + count; | |
575 | return count; | |
576 | } | |
577 | ||
6d1029b5 AM |
578 | /** |
579 | * memory_read_from_buffer - copy data from the buffer | |
580 | * @to: the kernel space buffer to read to | |
581 | * @count: the maximum number of bytes to read | |
582 | * @ppos: the current position in the buffer | |
583 | * @from: the buffer to read from | |
584 | * @available: the size of the buffer | |
585 | * | |
586 | * The memory_read_from_buffer() function reads up to @count bytes from the | |
587 | * buffer @from at offset @ppos into the kernel space address starting at @to. | |
588 | * | |
589 | * On success, the number of bytes read is returned and the offset @ppos is | |
590 | * advanced by this number, or negative value is returned on error. | |
591 | **/ | |
93b07113 AM |
592 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
593 | const void *from, size_t available) | |
594 | { | |
595 | loff_t pos = *ppos; | |
596 | ||
597 | if (pos < 0) | |
598 | return -EINVAL; | |
599 | if (pos >= available) | |
600 | return 0; | |
601 | if (count > available - pos) | |
602 | count = available - pos; | |
603 | memcpy(to, from + pos, count); | |
604 | *ppos = pos + count; | |
605 | ||
606 | return count; | |
607 | } | |
608 | ||
1da177e4 LT |
609 | /* |
610 | * Transaction based IO. | |
611 | * The file expects a single write which triggers the transaction, and then | |
612 | * possibly a read which collects the result - which is stored in a | |
613 | * file-local buffer. | |
614 | */ | |
76791ab2 IM |
615 | |
616 | void simple_transaction_set(struct file *file, size_t n) | |
617 | { | |
618 | struct simple_transaction_argresp *ar = file->private_data; | |
619 | ||
620 | BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); | |
621 | ||
622 | /* | |
623 | * The barrier ensures that ar->size will really remain zero until | |
624 | * ar->data is ready for reading. | |
625 | */ | |
626 | smp_mb(); | |
627 | ar->size = n; | |
628 | } | |
629 | ||
1da177e4 LT |
630 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
631 | { | |
632 | struct simple_transaction_argresp *ar; | |
633 | static DEFINE_SPINLOCK(simple_transaction_lock); | |
634 | ||
635 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) | |
636 | return ERR_PTR(-EFBIG); | |
637 | ||
638 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); | |
639 | if (!ar) | |
640 | return ERR_PTR(-ENOMEM); | |
641 | ||
642 | spin_lock(&simple_transaction_lock); | |
643 | ||
644 | /* only one write allowed per open */ | |
645 | if (file->private_data) { | |
646 | spin_unlock(&simple_transaction_lock); | |
647 | free_page((unsigned long)ar); | |
648 | return ERR_PTR(-EBUSY); | |
649 | } | |
650 | ||
651 | file->private_data = ar; | |
652 | ||
653 | spin_unlock(&simple_transaction_lock); | |
654 | ||
655 | if (copy_from_user(ar->data, buf, size)) | |
656 | return ERR_PTR(-EFAULT); | |
657 | ||
658 | return ar->data; | |
659 | } | |
660 | ||
661 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) | |
662 | { | |
663 | struct simple_transaction_argresp *ar = file->private_data; | |
664 | ||
665 | if (!ar) | |
666 | return 0; | |
667 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); | |
668 | } | |
669 | ||
670 | int simple_transaction_release(struct inode *inode, struct file *file) | |
671 | { | |
672 | free_page((unsigned long)file->private_data); | |
673 | return 0; | |
674 | } | |
675 | ||
acaefc25 AB |
676 | /* Simple attribute files */ |
677 | ||
678 | struct simple_attr { | |
8b88b099 CH |
679 | int (*get)(void *, u64 *); |
680 | int (*set)(void *, u64); | |
acaefc25 AB |
681 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
682 | char set_buf[24]; | |
683 | void *data; | |
684 | const char *fmt; /* format for read operation */ | |
7cf34c76 | 685 | struct mutex mutex; /* protects access to these buffers */ |
acaefc25 AB |
686 | }; |
687 | ||
688 | /* simple_attr_open is called by an actual attribute open file operation | |
689 | * to set the attribute specific access operations. */ | |
690 | int simple_attr_open(struct inode *inode, struct file *file, | |
8b88b099 | 691 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
acaefc25 AB |
692 | const char *fmt) |
693 | { | |
694 | struct simple_attr *attr; | |
695 | ||
696 | attr = kmalloc(sizeof(*attr), GFP_KERNEL); | |
697 | if (!attr) | |
698 | return -ENOMEM; | |
699 | ||
700 | attr->get = get; | |
701 | attr->set = set; | |
8e18e294 | 702 | attr->data = inode->i_private; |
acaefc25 | 703 | attr->fmt = fmt; |
7cf34c76 | 704 | mutex_init(&attr->mutex); |
acaefc25 AB |
705 | |
706 | file->private_data = attr; | |
707 | ||
708 | return nonseekable_open(inode, file); | |
709 | } | |
710 | ||
74bedc4d | 711 | int simple_attr_release(struct inode *inode, struct file *file) |
acaefc25 AB |
712 | { |
713 | kfree(file->private_data); | |
714 | return 0; | |
715 | } | |
716 | ||
717 | /* read from the buffer that is filled with the get function */ | |
718 | ssize_t simple_attr_read(struct file *file, char __user *buf, | |
719 | size_t len, loff_t *ppos) | |
720 | { | |
721 | struct simple_attr *attr; | |
722 | size_t size; | |
723 | ssize_t ret; | |
724 | ||
725 | attr = file->private_data; | |
726 | ||
727 | if (!attr->get) | |
728 | return -EACCES; | |
729 | ||
9261303a CH |
730 | ret = mutex_lock_interruptible(&attr->mutex); |
731 | if (ret) | |
732 | return ret; | |
733 | ||
8b88b099 | 734 | if (*ppos) { /* continued read */ |
acaefc25 | 735 | size = strlen(attr->get_buf); |
8b88b099 CH |
736 | } else { /* first read */ |
737 | u64 val; | |
738 | ret = attr->get(attr->data, &val); | |
739 | if (ret) | |
740 | goto out; | |
741 | ||
acaefc25 | 742 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
8b88b099 CH |
743 | attr->fmt, (unsigned long long)val); |
744 | } | |
acaefc25 AB |
745 | |
746 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); | |
8b88b099 | 747 | out: |
7cf34c76 | 748 | mutex_unlock(&attr->mutex); |
acaefc25 AB |
749 | return ret; |
750 | } | |
751 | ||
752 | /* interpret the buffer as a number to call the set function with */ | |
753 | ssize_t simple_attr_write(struct file *file, const char __user *buf, | |
754 | size_t len, loff_t *ppos) | |
755 | { | |
756 | struct simple_attr *attr; | |
757 | u64 val; | |
758 | size_t size; | |
759 | ssize_t ret; | |
760 | ||
761 | attr = file->private_data; | |
acaefc25 AB |
762 | if (!attr->set) |
763 | return -EACCES; | |
764 | ||
9261303a CH |
765 | ret = mutex_lock_interruptible(&attr->mutex); |
766 | if (ret) | |
767 | return ret; | |
768 | ||
acaefc25 AB |
769 | ret = -EFAULT; |
770 | size = min(sizeof(attr->set_buf) - 1, len); | |
771 | if (copy_from_user(attr->set_buf, buf, size)) | |
772 | goto out; | |
773 | ||
acaefc25 AB |
774 | attr->set_buf[size] = '\0'; |
775 | val = simple_strtol(attr->set_buf, NULL, 0); | |
05cc0cee WF |
776 | ret = attr->set(attr->data, val); |
777 | if (ret == 0) | |
778 | ret = len; /* on success, claim we got the whole input */ | |
acaefc25 | 779 | out: |
7cf34c76 | 780 | mutex_unlock(&attr->mutex); |
acaefc25 AB |
781 | return ret; |
782 | } | |
783 | ||
2596110a CH |
784 | /** |
785 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation | |
786 | * @sb: filesystem to do the file handle conversion on | |
787 | * @fid: file handle to convert | |
788 | * @fh_len: length of the file handle in bytes | |
789 | * @fh_type: type of file handle | |
790 | * @get_inode: filesystem callback to retrieve inode | |
791 | * | |
792 | * This function decodes @fid as long as it has one of the well-known | |
793 | * Linux filehandle types and calls @get_inode on it to retrieve the | |
794 | * inode for the object specified in the file handle. | |
795 | */ | |
796 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, | |
797 | int fh_len, int fh_type, struct inode *(*get_inode) | |
798 | (struct super_block *sb, u64 ino, u32 gen)) | |
799 | { | |
800 | struct inode *inode = NULL; | |
801 | ||
802 | if (fh_len < 2) | |
803 | return NULL; | |
804 | ||
805 | switch (fh_type) { | |
806 | case FILEID_INO32_GEN: | |
807 | case FILEID_INO32_GEN_PARENT: | |
808 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); | |
809 | break; | |
810 | } | |
811 | ||
4ea3ada2 | 812 | return d_obtain_alias(inode); |
2596110a CH |
813 | } |
814 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); | |
815 | ||
816 | /** | |
817 | * generic_fh_to_dentry - generic helper for the fh_to_parent export operation | |
818 | * @sb: filesystem to do the file handle conversion on | |
819 | * @fid: file handle to convert | |
820 | * @fh_len: length of the file handle in bytes | |
821 | * @fh_type: type of file handle | |
822 | * @get_inode: filesystem callback to retrieve inode | |
823 | * | |
824 | * This function decodes @fid as long as it has one of the well-known | |
825 | * Linux filehandle types and calls @get_inode on it to retrieve the | |
826 | * inode for the _parent_ object specified in the file handle if it | |
827 | * is specified in the file handle, or NULL otherwise. | |
828 | */ | |
829 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, | |
830 | int fh_len, int fh_type, struct inode *(*get_inode) | |
831 | (struct super_block *sb, u64 ino, u32 gen)) | |
832 | { | |
833 | struct inode *inode = NULL; | |
834 | ||
835 | if (fh_len <= 2) | |
836 | return NULL; | |
837 | ||
838 | switch (fh_type) { | |
839 | case FILEID_INO32_GEN_PARENT: | |
840 | inode = get_inode(sb, fid->i32.parent_ino, | |
841 | (fh_len > 3 ? fid->i32.parent_gen : 0)); | |
842 | break; | |
843 | } | |
844 | ||
4ea3ada2 | 845 | return d_obtain_alias(inode); |
2596110a CH |
846 | } |
847 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); | |
848 | ||
1b061d92 CH |
849 | /** |
850 | * generic_file_fsync - generic fsync implementation for simple filesystems | |
851 | * @file: file to synchronize | |
852 | * @datasync: only synchronize essential metadata if true | |
853 | * | |
854 | * This is a generic implementation of the fsync method for simple | |
855 | * filesystems which track all non-inode metadata in the buffers list | |
856 | * hanging off the address_space structure. | |
857 | */ | |
858 | int generic_file_fsync(struct file *file, int datasync) | |
d5aacad5 AV |
859 | { |
860 | struct writeback_control wbc = { | |
861 | .sync_mode = WB_SYNC_ALL, | |
862 | .nr_to_write = 0, /* metadata-only; caller takes care of data */ | |
863 | }; | |
7ea80859 | 864 | struct inode *inode = file->f_mapping->host; |
d5aacad5 AV |
865 | int err; |
866 | int ret; | |
867 | ||
868 | ret = sync_mapping_buffers(inode->i_mapping); | |
869 | if (!(inode->i_state & I_DIRTY)) | |
870 | return ret; | |
871 | if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) | |
872 | return ret; | |
873 | ||
874 | err = sync_inode(inode, &wbc); | |
875 | if (ret == 0) | |
876 | ret = err; | |
877 | return ret; | |
878 | } | |
1b061d92 CH |
879 | EXPORT_SYMBOL(generic_file_fsync); |
880 | ||
881 | /* | |
882 | * No-op implementation of ->fsync for in-memory filesystems. | |
883 | */ | |
884 | int noop_fsync(struct file *file, int datasync) | |
885 | { | |
886 | return 0; | |
887 | } | |
d5aacad5 | 888 | |
1da177e4 LT |
889 | EXPORT_SYMBOL(dcache_dir_close); |
890 | EXPORT_SYMBOL(dcache_dir_lseek); | |
891 | EXPORT_SYMBOL(dcache_dir_open); | |
892 | EXPORT_SYMBOL(dcache_readdir); | |
893 | EXPORT_SYMBOL(generic_read_dir); | |
894 | EXPORT_SYMBOL(get_sb_pseudo); | |
afddba49 NP |
895 | EXPORT_SYMBOL(simple_write_begin); |
896 | EXPORT_SYMBOL(simple_write_end); | |
1da177e4 LT |
897 | EXPORT_SYMBOL(simple_dir_inode_operations); |
898 | EXPORT_SYMBOL(simple_dir_operations); | |
899 | EXPORT_SYMBOL(simple_empty); | |
1da177e4 LT |
900 | EXPORT_SYMBOL(simple_fill_super); |
901 | EXPORT_SYMBOL(simple_getattr); | |
902 | EXPORT_SYMBOL(simple_link); | |
903 | EXPORT_SYMBOL(simple_lookup); | |
904 | EXPORT_SYMBOL(simple_pin_fs); | |
1da177e4 LT |
905 | EXPORT_SYMBOL(simple_readpage); |
906 | EXPORT_SYMBOL(simple_release_fs); | |
907 | EXPORT_SYMBOL(simple_rename); | |
908 | EXPORT_SYMBOL(simple_rmdir); | |
909 | EXPORT_SYMBOL(simple_statfs); | |
1b061d92 | 910 | EXPORT_SYMBOL(noop_fsync); |
1da177e4 LT |
911 | EXPORT_SYMBOL(simple_unlink); |
912 | EXPORT_SYMBOL(simple_read_from_buffer); | |
6a727b43 | 913 | EXPORT_SYMBOL(simple_write_to_buffer); |
93b07113 | 914 | EXPORT_SYMBOL(memory_read_from_buffer); |
76791ab2 | 915 | EXPORT_SYMBOL(simple_transaction_set); |
1da177e4 LT |
916 | EXPORT_SYMBOL(simple_transaction_get); |
917 | EXPORT_SYMBOL(simple_transaction_read); | |
918 | EXPORT_SYMBOL(simple_transaction_release); | |
acaefc25 | 919 | EXPORT_SYMBOL_GPL(simple_attr_open); |
74bedc4d | 920 | EXPORT_SYMBOL_GPL(simple_attr_release); |
acaefc25 AB |
921 | EXPORT_SYMBOL_GPL(simple_attr_read); |
922 | EXPORT_SYMBOL_GPL(simple_attr_write); |