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> | |
7bb46a67 | 11 | #include <linux/quotaops.h> |
7cf34c76 | 12 | #include <linux/mutex.h> |
2596110a | 13 | #include <linux/exportfs.h> |
d5aacad5 AV |
14 | #include <linux/writeback.h> |
15 | #include <linux/buffer_head.h> | |
7cf34c76 | 16 | |
1da177e4 LT |
17 | #include <asm/uaccess.h> |
18 | ||
19 | int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
20 | struct kstat *stat) | |
21 | { | |
22 | struct inode *inode = dentry->d_inode; | |
23 | generic_fillattr(inode, stat); | |
24 | stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); | |
25 | return 0; | |
26 | } | |
27 | ||
726c3342 | 28 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
1da177e4 | 29 | { |
726c3342 | 30 | buf->f_type = dentry->d_sb->s_magic; |
1da177e4 LT |
31 | buf->f_bsize = PAGE_CACHE_SIZE; |
32 | buf->f_namelen = NAME_MAX; | |
33 | return 0; | |
34 | } | |
35 | ||
36 | /* | |
37 | * Retaining negative dentries for an in-memory filesystem just wastes | |
38 | * memory and lookup time: arrange for them to be deleted immediately. | |
39 | */ | |
40 | static int simple_delete_dentry(struct dentry *dentry) | |
41 | { | |
42 | return 1; | |
43 | } | |
44 | ||
45 | /* | |
46 | * Lookup the data. This is trivial - if the dentry didn't already | |
47 | * exist, we know it is negative. Set d_op to delete negative dentries. | |
48 | */ | |
49 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) | |
50 | { | |
3ba13d17 | 51 | static const struct dentry_operations simple_dentry_operations = { |
1da177e4 LT |
52 | .d_delete = simple_delete_dentry, |
53 | }; | |
54 | ||
55 | if (dentry->d_name.len > NAME_MAX) | |
56 | return ERR_PTR(-ENAMETOOLONG); | |
57 | dentry->d_op = &simple_dentry_operations; | |
58 | d_add(dentry, NULL); | |
59 | return NULL; | |
60 | } | |
61 | ||
1da177e4 LT |
62 | int dcache_dir_open(struct inode *inode, struct file *file) |
63 | { | |
64 | static struct qstr cursor_name = {.len = 1, .name = "."}; | |
65 | ||
0f7fc9e4 | 66 | file->private_data = d_alloc(file->f_path.dentry, &cursor_name); |
1da177e4 LT |
67 | |
68 | return file->private_data ? 0 : -ENOMEM; | |
69 | } | |
70 | ||
71 | int dcache_dir_close(struct inode *inode, struct file *file) | |
72 | { | |
73 | dput(file->private_data); | |
74 | return 0; | |
75 | } | |
76 | ||
77 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) | |
78 | { | |
0f7fc9e4 | 79 | mutex_lock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
80 | switch (origin) { |
81 | case 1: | |
82 | offset += file->f_pos; | |
83 | case 0: | |
84 | if (offset >= 0) | |
85 | break; | |
86 | default: | |
0f7fc9e4 | 87 | mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
88 | return -EINVAL; |
89 | } | |
90 | if (offset != file->f_pos) { | |
91 | file->f_pos = offset; | |
92 | if (file->f_pos >= 2) { | |
93 | struct list_head *p; | |
94 | struct dentry *cursor = file->private_data; | |
95 | loff_t n = file->f_pos - 2; | |
96 | ||
97 | spin_lock(&dcache_lock); | |
5160ee6f | 98 | list_del(&cursor->d_u.d_child); |
0f7fc9e4 JJS |
99 | p = file->f_path.dentry->d_subdirs.next; |
100 | while (n && p != &file->f_path.dentry->d_subdirs) { | |
1da177e4 | 101 | struct dentry *next; |
5160ee6f | 102 | next = list_entry(p, struct dentry, d_u.d_child); |
1da177e4 LT |
103 | if (!d_unhashed(next) && next->d_inode) |
104 | n--; | |
105 | p = p->next; | |
106 | } | |
5160ee6f | 107 | list_add_tail(&cursor->d_u.d_child, p); |
1da177e4 LT |
108 | spin_unlock(&dcache_lock); |
109 | } | |
110 | } | |
0f7fc9e4 | 111 | mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); |
1da177e4 LT |
112 | return offset; |
113 | } | |
114 | ||
115 | /* Relationship between i_mode and the DT_xxx types */ | |
116 | static inline unsigned char dt_type(struct inode *inode) | |
117 | { | |
118 | return (inode->i_mode >> 12) & 15; | |
119 | } | |
120 | ||
121 | /* | |
122 | * Directory is locked and all positive dentries in it are safe, since | |
123 | * for ramfs-type trees they can't go away without unlink() or rmdir(), | |
124 | * both impossible due to the lock on directory. | |
125 | */ | |
126 | ||
127 | int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) | |
128 | { | |
0f7fc9e4 | 129 | struct dentry *dentry = filp->f_path.dentry; |
1da177e4 | 130 | struct dentry *cursor = filp->private_data; |
5160ee6f | 131 | struct list_head *p, *q = &cursor->d_u.d_child; |
1da177e4 LT |
132 | ino_t ino; |
133 | int i = filp->f_pos; | |
134 | ||
135 | switch (i) { | |
136 | case 0: | |
137 | ino = dentry->d_inode->i_ino; | |
138 | if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) | |
139 | break; | |
140 | filp->f_pos++; | |
141 | i++; | |
142 | /* fallthrough */ | |
143 | case 1: | |
144 | ino = parent_ino(dentry); | |
145 | if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) | |
146 | break; | |
147 | filp->f_pos++; | |
148 | i++; | |
149 | /* fallthrough */ | |
150 | default: | |
151 | spin_lock(&dcache_lock); | |
1bfba4e8 AM |
152 | if (filp->f_pos == 2) |
153 | list_move(q, &dentry->d_subdirs); | |
154 | ||
1da177e4 LT |
155 | for (p=q->next; p != &dentry->d_subdirs; p=p->next) { |
156 | struct dentry *next; | |
5160ee6f | 157 | next = list_entry(p, struct dentry, d_u.d_child); |
1da177e4 LT |
158 | if (d_unhashed(next) || !next->d_inode) |
159 | continue; | |
160 | ||
161 | spin_unlock(&dcache_lock); | |
0f8952c2 RN |
162 | if (filldir(dirent, next->d_name.name, |
163 | next->d_name.len, filp->f_pos, | |
164 | next->d_inode->i_ino, | |
165 | dt_type(next->d_inode)) < 0) | |
1da177e4 LT |
166 | return 0; |
167 | spin_lock(&dcache_lock); | |
168 | /* next is still alive */ | |
1bfba4e8 | 169 | list_move(q, p); |
1da177e4 LT |
170 | p = q; |
171 | filp->f_pos++; | |
172 | } | |
173 | spin_unlock(&dcache_lock); | |
174 | } | |
175 | return 0; | |
176 | } | |
177 | ||
178 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) | |
179 | { | |
180 | return -EISDIR; | |
181 | } | |
182 | ||
4b6f5d20 | 183 | const struct file_operations simple_dir_operations = { |
1da177e4 LT |
184 | .open = dcache_dir_open, |
185 | .release = dcache_dir_close, | |
186 | .llseek = dcache_dir_lseek, | |
187 | .read = generic_read_dir, | |
188 | .readdir = dcache_readdir, | |
1b061d92 | 189 | .fsync = noop_fsync, |
1da177e4 LT |
190 | }; |
191 | ||
92e1d5be | 192 | const struct inode_operations simple_dir_inode_operations = { |
1da177e4 LT |
193 | .lookup = simple_lookup, |
194 | }; | |
195 | ||
759b9775 HD |
196 | static const struct super_operations simple_super_operations = { |
197 | .statfs = simple_statfs, | |
198 | }; | |
199 | ||
1da177e4 LT |
200 | /* |
201 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that | |
202 | * will never be mountable) | |
203 | */ | |
454e2398 | 204 | int get_sb_pseudo(struct file_system_type *fs_type, char *name, |
ee9b6d61 | 205 | const struct super_operations *ops, unsigned long magic, |
454e2398 | 206 | struct vfsmount *mnt) |
1da177e4 LT |
207 | { |
208 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
1da177e4 LT |
209 | struct dentry *dentry; |
210 | struct inode *root; | |
211 | struct qstr d_name = {.name = name, .len = strlen(name)}; | |
212 | ||
213 | if (IS_ERR(s)) | |
454e2398 | 214 | return PTR_ERR(s); |
1da177e4 LT |
215 | |
216 | s->s_flags = MS_NOUSER; | |
89a4eb4b | 217 | s->s_maxbytes = MAX_LFS_FILESIZE; |
3971e1a9 AN |
218 | s->s_blocksize = PAGE_SIZE; |
219 | s->s_blocksize_bits = PAGE_SHIFT; | |
1da177e4 | 220 | s->s_magic = magic; |
759b9775 | 221 | s->s_op = ops ? ops : &simple_super_operations; |
1da177e4 LT |
222 | s->s_time_gran = 1; |
223 | root = new_inode(s); | |
224 | if (!root) | |
225 | goto Enomem; | |
1a1c9bb4 JL |
226 | /* |
227 | * since this is the first inode, make it number 1. New inodes created | |
228 | * after this must take care not to collide with it (by passing | |
229 | * max_reserved of 1 to iunique). | |
230 | */ | |
231 | root->i_ino = 1; | |
1da177e4 | 232 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
1da177e4 LT |
233 | root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; |
234 | dentry = d_alloc(NULL, &d_name); | |
235 | if (!dentry) { | |
236 | iput(root); | |
237 | goto Enomem; | |
238 | } | |
239 | dentry->d_sb = s; | |
240 | dentry->d_parent = dentry; | |
241 | d_instantiate(dentry, root); | |
242 | s->s_root = dentry; | |
243 | s->s_flags |= MS_ACTIVE; | |
a3ec947c SB |
244 | simple_set_mnt(mnt, s); |
245 | return 0; | |
1da177e4 LT |
246 | |
247 | Enomem: | |
6f5bbff9 | 248 | deactivate_locked_super(s); |
454e2398 | 249 | return -ENOMEM; |
1da177e4 LT |
250 | } |
251 | ||
252 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
253 | { | |
254 | struct inode *inode = old_dentry->d_inode; | |
255 | ||
256 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
d8c76e6f | 257 | inc_nlink(inode); |
1da177e4 LT |
258 | atomic_inc(&inode->i_count); |
259 | dget(dentry); | |
260 | d_instantiate(dentry, inode); | |
261 | return 0; | |
262 | } | |
263 | ||
264 | static inline int simple_positive(struct dentry *dentry) | |
265 | { | |
266 | return dentry->d_inode && !d_unhashed(dentry); | |
267 | } | |
268 | ||
269 | int simple_empty(struct dentry *dentry) | |
270 | { | |
271 | struct dentry *child; | |
272 | int ret = 0; | |
273 | ||
274 | spin_lock(&dcache_lock); | |
5160ee6f | 275 | list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) |
1da177e4 LT |
276 | if (simple_positive(child)) |
277 | goto out; | |
278 | ret = 1; | |
279 | out: | |
280 | spin_unlock(&dcache_lock); | |
281 | return ret; | |
282 | } | |
283 | ||
284 | int simple_unlink(struct inode *dir, struct dentry *dentry) | |
285 | { | |
286 | struct inode *inode = dentry->d_inode; | |
287 | ||
288 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
9a53c3a7 | 289 | drop_nlink(inode); |
1da177e4 LT |
290 | dput(dentry); |
291 | return 0; | |
292 | } | |
293 | ||
294 | int simple_rmdir(struct inode *dir, struct dentry *dentry) | |
295 | { | |
296 | if (!simple_empty(dentry)) | |
297 | return -ENOTEMPTY; | |
298 | ||
9a53c3a7 | 299 | drop_nlink(dentry->d_inode); |
1da177e4 | 300 | simple_unlink(dir, dentry); |
9a53c3a7 | 301 | drop_nlink(dir); |
1da177e4 LT |
302 | return 0; |
303 | } | |
304 | ||
305 | int simple_rename(struct inode *old_dir, struct dentry *old_dentry, | |
306 | struct inode *new_dir, struct dentry *new_dentry) | |
307 | { | |
308 | struct inode *inode = old_dentry->d_inode; | |
309 | int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); | |
310 | ||
311 | if (!simple_empty(new_dentry)) | |
312 | return -ENOTEMPTY; | |
313 | ||
314 | if (new_dentry->d_inode) { | |
315 | simple_unlink(new_dir, new_dentry); | |
316 | if (they_are_dirs) | |
9a53c3a7 | 317 | drop_nlink(old_dir); |
1da177e4 | 318 | } else if (they_are_dirs) { |
9a53c3a7 | 319 | drop_nlink(old_dir); |
d8c76e6f | 320 | inc_nlink(new_dir); |
1da177e4 LT |
321 | } |
322 | ||
323 | old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = | |
324 | new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; | |
325 | ||
326 | return 0; | |
327 | } | |
328 | ||
7bb46a67 | 329 | /** |
330 | * simple_setsize - handle core mm and vfs requirements for file size change | |
331 | * @inode: inode | |
332 | * @newsize: new file size | |
333 | * | |
334 | * Returns 0 on success, -error on failure. | |
335 | * | |
336 | * simple_setsize must be called with inode_mutex held. | |
337 | * | |
338 | * simple_setsize will check that the requested new size is OK (see | |
339 | * inode_newsize_ok), and then will perform the necessary i_size update | |
340 | * and pagecache truncation (if necessary). It will be typically be called | |
341 | * from the filesystem's setattr function when ATTR_SIZE is passed in. | |
342 | * | |
343 | * The inode itself must have correct permissions and attributes to allow | |
344 | * i_size to be changed, this function then just checks that the new size | |
345 | * requested is valid. | |
346 | * | |
347 | * In the case of simple in-memory filesystems with inodes stored solely | |
348 | * in the inode cache, and file data in the pagecache, nothing more needs | |
349 | * to be done to satisfy a truncate request. Filesystems with on-disk | |
350 | * blocks for example will need to free them in the case of truncate, in | |
351 | * that case it may be easier not to use simple_setsize (but each of its | |
352 | * components will likely be required at some point to update pagecache | |
353 | * and inode etc). | |
354 | */ | |
355 | int simple_setsize(struct inode *inode, loff_t newsize) | |
356 | { | |
357 | loff_t oldsize; | |
358 | int error; | |
359 | ||
360 | error = inode_newsize_ok(inode, newsize); | |
361 | if (error) | |
362 | return error; | |
363 | ||
364 | oldsize = inode->i_size; | |
365 | i_size_write(inode, newsize); | |
366 | truncate_pagecache(inode, oldsize, newsize); | |
367 | ||
368 | return error; | |
369 | } | |
370 | EXPORT_SYMBOL(simple_setsize); | |
371 | ||
372 | /** | |
373 | * simple_setattr - setattr for simple in-memory filesystem | |
374 | * @dentry: dentry | |
375 | * @iattr: iattr structure | |
376 | * | |
377 | * Returns 0 on success, -error on failure. | |
378 | * | |
379 | * simple_setattr implements setattr for an in-memory filesystem which | |
380 | * does not store its own file data or metadata (eg. uses the page cache | |
381 | * and inode cache as its data store). | |
382 | */ | |
383 | int simple_setattr(struct dentry *dentry, struct iattr *iattr) | |
384 | { | |
385 | struct inode *inode = dentry->d_inode; | |
386 | int error; | |
387 | ||
388 | error = inode_change_ok(inode, iattr); | |
389 | if (error) | |
390 | return error; | |
391 | ||
392 | if (iattr->ia_valid & ATTR_SIZE) { | |
393 | error = simple_setsize(inode, iattr->ia_size); | |
394 | if (error) | |
395 | return error; | |
396 | } | |
397 | ||
398 | generic_setattr(inode, iattr); | |
399 | ||
400 | return error; | |
401 | } | |
402 | EXPORT_SYMBOL(simple_setattr); | |
403 | ||
1da177e4 LT |
404 | int simple_readpage(struct file *file, struct page *page) |
405 | { | |
c0d92cbc | 406 | clear_highpage(page); |
1da177e4 LT |
407 | flush_dcache_page(page); |
408 | SetPageUptodate(page); | |
1da177e4 LT |
409 | unlock_page(page); |
410 | return 0; | |
411 | } | |
412 | ||
afddba49 NP |
413 | int simple_write_begin(struct file *file, struct address_space *mapping, |
414 | loff_t pos, unsigned len, unsigned flags, | |
415 | struct page **pagep, void **fsdata) | |
416 | { | |
417 | struct page *page; | |
418 | pgoff_t index; | |
afddba49 NP |
419 | |
420 | index = pos >> PAGE_CACHE_SHIFT; | |
afddba49 | 421 | |
54566b2c | 422 | page = grab_cache_page_write_begin(mapping, index, flags); |
afddba49 NP |
423 | if (!page) |
424 | return -ENOMEM; | |
425 | ||
426 | *pagep = page; | |
427 | ||
193cf4b9 BH |
428 | if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { |
429 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); | |
430 | ||
431 | zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); | |
432 | } | |
433 | return 0; | |
afddba49 NP |
434 | } |
435 | ||
ad2a722f BH |
436 | /** |
437 | * simple_write_end - .write_end helper for non-block-device FSes | |
438 | * @available: See .write_end of address_space_operations | |
439 | * @file: " | |
440 | * @mapping: " | |
441 | * @pos: " | |
442 | * @len: " | |
443 | * @copied: " | |
444 | * @page: " | |
445 | * @fsdata: " | |
446 | * | |
447 | * simple_write_end does the minimum needed for updating a page after writing is | |
448 | * done. It has the same API signature as the .write_end of | |
449 | * address_space_operations vector. So it can just be set onto .write_end for | |
450 | * FSes that don't need any other processing. i_mutex is assumed to be held. | |
451 | * Block based filesystems should use generic_write_end(). | |
452 | * NOTE: Even though i_size might get updated by this function, mark_inode_dirty | |
453 | * is not called, so a filesystem that actually does store data in .write_inode | |
454 | * should extend on what's done here with a call to mark_inode_dirty() in the | |
455 | * case that i_size has changed. | |
456 | */ | |
afddba49 NP |
457 | int simple_write_end(struct file *file, struct address_space *mapping, |
458 | loff_t pos, unsigned len, unsigned copied, | |
459 | struct page *page, void *fsdata) | |
460 | { | |
ad2a722f BH |
461 | struct inode *inode = page->mapping->host; |
462 | loff_t last_pos = pos + copied; | |
afddba49 NP |
463 | |
464 | /* zero the stale part of the page if we did a short copy */ | |
465 | if (copied < len) { | |
ad2a722f BH |
466 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
467 | ||
468 | zero_user(page, from + copied, len - copied); | |
afddba49 NP |
469 | } |
470 | ||
ad2a722f BH |
471 | if (!PageUptodate(page)) |
472 | SetPageUptodate(page); | |
473 | /* | |
474 | * No need to use i_size_read() here, the i_size | |
475 | * cannot change under us because we hold the i_mutex. | |
476 | */ | |
477 | if (last_pos > inode->i_size) | |
478 | i_size_write(inode, last_pos); | |
afddba49 | 479 | |
ad2a722f | 480 | set_page_dirty(page); |
afddba49 NP |
481 | unlock_page(page); |
482 | page_cache_release(page); | |
483 | ||
484 | return copied; | |
485 | } | |
486 | ||
1a1c9bb4 JL |
487 | /* |
488 | * the inodes created here are not hashed. If you use iunique to generate | |
489 | * unique inode values later for this filesystem, then you must take care | |
490 | * to pass it an appropriate max_reserved value to avoid collisions. | |
491 | */ | |
7d683a09 RS |
492 | int simple_fill_super(struct super_block *s, unsigned long magic, |
493 | struct tree_descr *files) | |
1da177e4 | 494 | { |
1da177e4 LT |
495 | struct inode *inode; |
496 | struct dentry *root; | |
497 | struct dentry *dentry; | |
498 | int i; | |
499 | ||
500 | s->s_blocksize = PAGE_CACHE_SIZE; | |
501 | s->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
502 | s->s_magic = magic; | |
759b9775 | 503 | s->s_op = &simple_super_operations; |
1da177e4 LT |
504 | s->s_time_gran = 1; |
505 | ||
506 | inode = new_inode(s); | |
507 | if (!inode) | |
508 | return -ENOMEM; | |
1a1c9bb4 JL |
509 | /* |
510 | * because the root inode is 1, the files array must not contain an | |
511 | * entry at index 1 | |
512 | */ | |
513 | inode->i_ino = 1; | |
1da177e4 | 514 | inode->i_mode = S_IFDIR | 0755; |
1da177e4 LT |
515 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
516 | inode->i_op = &simple_dir_inode_operations; | |
517 | inode->i_fop = &simple_dir_operations; | |
7656f328 | 518 | inode->i_nlink = 2; |
1da177e4 LT |
519 | root = d_alloc_root(inode); |
520 | if (!root) { | |
521 | iput(inode); | |
522 | return -ENOMEM; | |
523 | } | |
524 | for (i = 0; !files->name || files->name[0]; i++, files++) { | |
525 | if (!files->name) | |
526 | continue; | |
1a1c9bb4 JL |
527 | |
528 | /* warn if it tries to conflict with the root inode */ | |
529 | if (unlikely(i == 1)) | |
530 | printk(KERN_WARNING "%s: %s passed in a files array" | |
531 | "with an index of 1!\n", __func__, | |
532 | s->s_type->name); | |
533 | ||
1da177e4 LT |
534 | dentry = d_alloc_name(root, files->name); |
535 | if (!dentry) | |
536 | goto out; | |
537 | inode = new_inode(s); | |
538 | if (!inode) | |
539 | goto out; | |
540 | inode->i_mode = S_IFREG | files->mode; | |
1da177e4 LT |
541 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
542 | inode->i_fop = files->ops; | |
543 | inode->i_ino = i; | |
544 | d_add(dentry, inode); | |
545 | } | |
546 | s->s_root = root; | |
547 | return 0; | |
548 | out: | |
549 | d_genocide(root); | |
550 | dput(root); | |
551 | return -ENOMEM; | |
552 | } | |
553 | ||
554 | static DEFINE_SPINLOCK(pin_fs_lock); | |
555 | ||
1f5ce9e9 | 556 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
1da177e4 LT |
557 | { |
558 | struct vfsmount *mnt = NULL; | |
559 | spin_lock(&pin_fs_lock); | |
560 | if (unlikely(!*mount)) { | |
561 | spin_unlock(&pin_fs_lock); | |
1f5ce9e9 | 562 | mnt = vfs_kern_mount(type, 0, type->name, NULL); |
1da177e4 LT |
563 | if (IS_ERR(mnt)) |
564 | return PTR_ERR(mnt); | |
565 | spin_lock(&pin_fs_lock); | |
566 | if (!*mount) | |
567 | *mount = mnt; | |
568 | } | |
569 | mntget(*mount); | |
570 | ++*count; | |
571 | spin_unlock(&pin_fs_lock); | |
572 | mntput(mnt); | |
573 | return 0; | |
574 | } | |
575 | ||
576 | void simple_release_fs(struct vfsmount **mount, int *count) | |
577 | { | |
578 | struct vfsmount *mnt; | |
579 | spin_lock(&pin_fs_lock); | |
580 | mnt = *mount; | |
581 | if (!--*count) | |
582 | *mount = NULL; | |
583 | spin_unlock(&pin_fs_lock); | |
584 | mntput(mnt); | |
585 | } | |
586 | ||
6d1029b5 AM |
587 | /** |
588 | * simple_read_from_buffer - copy data from the buffer to user space | |
589 | * @to: the user space buffer to read to | |
590 | * @count: the maximum number of bytes to read | |
591 | * @ppos: the current position in the buffer | |
592 | * @from: the buffer to read from | |
593 | * @available: the size of the buffer | |
594 | * | |
595 | * The simple_read_from_buffer() function reads up to @count bytes from the | |
596 | * buffer @from at offset @ppos into the user space address starting at @to. | |
597 | * | |
598 | * On success, the number of bytes read is returned and the offset @ppos is | |
599 | * advanced by this number, or negative value is returned on error. | |
600 | **/ | |
1da177e4 LT |
601 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
602 | const void *from, size_t available) | |
603 | { | |
604 | loff_t pos = *ppos; | |
14be2746 SR |
605 | size_t ret; |
606 | ||
1da177e4 LT |
607 | if (pos < 0) |
608 | return -EINVAL; | |
14be2746 | 609 | if (pos >= available || !count) |
1da177e4 LT |
610 | return 0; |
611 | if (count > available - pos) | |
612 | count = available - pos; | |
14be2746 SR |
613 | ret = copy_to_user(to, from + pos, count); |
614 | if (ret == count) | |
1da177e4 | 615 | return -EFAULT; |
14be2746 | 616 | count -= ret; |
1da177e4 LT |
617 | *ppos = pos + count; |
618 | return count; | |
619 | } | |
620 | ||
6a727b43 JS |
621 | /** |
622 | * simple_write_to_buffer - copy data from user space to the buffer | |
623 | * @to: the buffer to write to | |
624 | * @available: the size of the buffer | |
625 | * @ppos: the current position in the buffer | |
626 | * @from: the user space buffer to read from | |
627 | * @count: the maximum number of bytes to read | |
628 | * | |
629 | * The simple_write_to_buffer() function reads up to @count bytes from the user | |
630 | * space address starting at @from into the buffer @to at offset @ppos. | |
631 | * | |
632 | * On success, the number of bytes written is returned and the offset @ppos is | |
633 | * advanced by this number, or negative value is returned on error. | |
634 | **/ | |
635 | ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, | |
636 | const void __user *from, size_t count) | |
637 | { | |
638 | loff_t pos = *ppos; | |
639 | size_t res; | |
640 | ||
641 | if (pos < 0) | |
642 | return -EINVAL; | |
643 | if (pos >= available || !count) | |
644 | return 0; | |
645 | if (count > available - pos) | |
646 | count = available - pos; | |
647 | res = copy_from_user(to + pos, from, count); | |
648 | if (res == count) | |
649 | return -EFAULT; | |
650 | count -= res; | |
651 | *ppos = pos + count; | |
652 | return count; | |
653 | } | |
654 | ||
6d1029b5 AM |
655 | /** |
656 | * memory_read_from_buffer - copy data from the buffer | |
657 | * @to: the kernel space buffer to read to | |
658 | * @count: the maximum number of bytes to read | |
659 | * @ppos: the current position in the buffer | |
660 | * @from: the buffer to read from | |
661 | * @available: the size of the buffer | |
662 | * | |
663 | * The memory_read_from_buffer() function reads up to @count bytes from the | |
664 | * buffer @from at offset @ppos into the kernel space address starting at @to. | |
665 | * | |
666 | * On success, the number of bytes read is returned and the offset @ppos is | |
667 | * advanced by this number, or negative value is returned on error. | |
668 | **/ | |
93b07113 AM |
669 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
670 | const void *from, size_t available) | |
671 | { | |
672 | loff_t pos = *ppos; | |
673 | ||
674 | if (pos < 0) | |
675 | return -EINVAL; | |
676 | if (pos >= available) | |
677 | return 0; | |
678 | if (count > available - pos) | |
679 | count = available - pos; | |
680 | memcpy(to, from + pos, count); | |
681 | *ppos = pos + count; | |
682 | ||
683 | return count; | |
684 | } | |
685 | ||
1da177e4 LT |
686 | /* |
687 | * Transaction based IO. | |
688 | * The file expects a single write which triggers the transaction, and then | |
689 | * possibly a read which collects the result - which is stored in a | |
690 | * file-local buffer. | |
691 | */ | |
76791ab2 IM |
692 | |
693 | void simple_transaction_set(struct file *file, size_t n) | |
694 | { | |
695 | struct simple_transaction_argresp *ar = file->private_data; | |
696 | ||
697 | BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); | |
698 | ||
699 | /* | |
700 | * The barrier ensures that ar->size will really remain zero until | |
701 | * ar->data is ready for reading. | |
702 | */ | |
703 | smp_mb(); | |
704 | ar->size = n; | |
705 | } | |
706 | ||
1da177e4 LT |
707 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
708 | { | |
709 | struct simple_transaction_argresp *ar; | |
710 | static DEFINE_SPINLOCK(simple_transaction_lock); | |
711 | ||
712 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) | |
713 | return ERR_PTR(-EFBIG); | |
714 | ||
715 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); | |
716 | if (!ar) | |
717 | return ERR_PTR(-ENOMEM); | |
718 | ||
719 | spin_lock(&simple_transaction_lock); | |
720 | ||
721 | /* only one write allowed per open */ | |
722 | if (file->private_data) { | |
723 | spin_unlock(&simple_transaction_lock); | |
724 | free_page((unsigned long)ar); | |
725 | return ERR_PTR(-EBUSY); | |
726 | } | |
727 | ||
728 | file->private_data = ar; | |
729 | ||
730 | spin_unlock(&simple_transaction_lock); | |
731 | ||
732 | if (copy_from_user(ar->data, buf, size)) | |
733 | return ERR_PTR(-EFAULT); | |
734 | ||
735 | return ar->data; | |
736 | } | |
737 | ||
738 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) | |
739 | { | |
740 | struct simple_transaction_argresp *ar = file->private_data; | |
741 | ||
742 | if (!ar) | |
743 | return 0; | |
744 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); | |
745 | } | |
746 | ||
747 | int simple_transaction_release(struct inode *inode, struct file *file) | |
748 | { | |
749 | free_page((unsigned long)file->private_data); | |
750 | return 0; | |
751 | } | |
752 | ||
acaefc25 AB |
753 | /* Simple attribute files */ |
754 | ||
755 | struct simple_attr { | |
8b88b099 CH |
756 | int (*get)(void *, u64 *); |
757 | int (*set)(void *, u64); | |
acaefc25 AB |
758 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
759 | char set_buf[24]; | |
760 | void *data; | |
761 | const char *fmt; /* format for read operation */ | |
7cf34c76 | 762 | struct mutex mutex; /* protects access to these buffers */ |
acaefc25 AB |
763 | }; |
764 | ||
765 | /* simple_attr_open is called by an actual attribute open file operation | |
766 | * to set the attribute specific access operations. */ | |
767 | int simple_attr_open(struct inode *inode, struct file *file, | |
8b88b099 | 768 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
acaefc25 AB |
769 | const char *fmt) |
770 | { | |
771 | struct simple_attr *attr; | |
772 | ||
773 | attr = kmalloc(sizeof(*attr), GFP_KERNEL); | |
774 | if (!attr) | |
775 | return -ENOMEM; | |
776 | ||
777 | attr->get = get; | |
778 | attr->set = set; | |
8e18e294 | 779 | attr->data = inode->i_private; |
acaefc25 | 780 | attr->fmt = fmt; |
7cf34c76 | 781 | mutex_init(&attr->mutex); |
acaefc25 AB |
782 | |
783 | file->private_data = attr; | |
784 | ||
785 | return nonseekable_open(inode, file); | |
786 | } | |
787 | ||
74bedc4d | 788 | int simple_attr_release(struct inode *inode, struct file *file) |
acaefc25 AB |
789 | { |
790 | kfree(file->private_data); | |
791 | return 0; | |
792 | } | |
793 | ||
794 | /* read from the buffer that is filled with the get function */ | |
795 | ssize_t simple_attr_read(struct file *file, char __user *buf, | |
796 | size_t len, loff_t *ppos) | |
797 | { | |
798 | struct simple_attr *attr; | |
799 | size_t size; | |
800 | ssize_t ret; | |
801 | ||
802 | attr = file->private_data; | |
803 | ||
804 | if (!attr->get) | |
805 | return -EACCES; | |
806 | ||
9261303a CH |
807 | ret = mutex_lock_interruptible(&attr->mutex); |
808 | if (ret) | |
809 | return ret; | |
810 | ||
8b88b099 | 811 | if (*ppos) { /* continued read */ |
acaefc25 | 812 | size = strlen(attr->get_buf); |
8b88b099 CH |
813 | } else { /* first read */ |
814 | u64 val; | |
815 | ret = attr->get(attr->data, &val); | |
816 | if (ret) | |
817 | goto out; | |
818 | ||
acaefc25 | 819 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
8b88b099 CH |
820 | attr->fmt, (unsigned long long)val); |
821 | } | |
acaefc25 AB |
822 | |
823 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); | |
8b88b099 | 824 | out: |
7cf34c76 | 825 | mutex_unlock(&attr->mutex); |
acaefc25 AB |
826 | return ret; |
827 | } | |
828 | ||
829 | /* interpret the buffer as a number to call the set function with */ | |
830 | ssize_t simple_attr_write(struct file *file, const char __user *buf, | |
831 | size_t len, loff_t *ppos) | |
832 | { | |
833 | struct simple_attr *attr; | |
834 | u64 val; | |
835 | size_t size; | |
836 | ssize_t ret; | |
837 | ||
838 | attr = file->private_data; | |
acaefc25 AB |
839 | if (!attr->set) |
840 | return -EACCES; | |
841 | ||
9261303a CH |
842 | ret = mutex_lock_interruptible(&attr->mutex); |
843 | if (ret) | |
844 | return ret; | |
845 | ||
acaefc25 AB |
846 | ret = -EFAULT; |
847 | size = min(sizeof(attr->set_buf) - 1, len); | |
848 | if (copy_from_user(attr->set_buf, buf, size)) | |
849 | goto out; | |
850 | ||
acaefc25 AB |
851 | attr->set_buf[size] = '\0'; |
852 | val = simple_strtol(attr->set_buf, NULL, 0); | |
05cc0cee WF |
853 | ret = attr->set(attr->data, val); |
854 | if (ret == 0) | |
855 | ret = len; /* on success, claim we got the whole input */ | |
acaefc25 | 856 | out: |
7cf34c76 | 857 | mutex_unlock(&attr->mutex); |
acaefc25 AB |
858 | return ret; |
859 | } | |
860 | ||
2596110a CH |
861 | /** |
862 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation | |
863 | * @sb: filesystem to do the file handle conversion on | |
864 | * @fid: file handle to convert | |
865 | * @fh_len: length of the file handle in bytes | |
866 | * @fh_type: type of file handle | |
867 | * @get_inode: filesystem callback to retrieve inode | |
868 | * | |
869 | * This function decodes @fid as long as it has one of the well-known | |
870 | * Linux filehandle types and calls @get_inode on it to retrieve the | |
871 | * inode for the object specified in the file handle. | |
872 | */ | |
873 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, | |
874 | int fh_len, int fh_type, struct inode *(*get_inode) | |
875 | (struct super_block *sb, u64 ino, u32 gen)) | |
876 | { | |
877 | struct inode *inode = NULL; | |
878 | ||
879 | if (fh_len < 2) | |
880 | return NULL; | |
881 | ||
882 | switch (fh_type) { | |
883 | case FILEID_INO32_GEN: | |
884 | case FILEID_INO32_GEN_PARENT: | |
885 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); | |
886 | break; | |
887 | } | |
888 | ||
4ea3ada2 | 889 | return d_obtain_alias(inode); |
2596110a CH |
890 | } |
891 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); | |
892 | ||
893 | /** | |
894 | * generic_fh_to_dentry - generic helper for the fh_to_parent export operation | |
895 | * @sb: filesystem to do the file handle conversion on | |
896 | * @fid: file handle to convert | |
897 | * @fh_len: length of the file handle in bytes | |
898 | * @fh_type: type of file handle | |
899 | * @get_inode: filesystem callback to retrieve inode | |
900 | * | |
901 | * This function decodes @fid as long as it has one of the well-known | |
902 | * Linux filehandle types and calls @get_inode on it to retrieve the | |
903 | * inode for the _parent_ object specified in the file handle if it | |
904 | * is specified in the file handle, or NULL otherwise. | |
905 | */ | |
906 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, | |
907 | int fh_len, int fh_type, struct inode *(*get_inode) | |
908 | (struct super_block *sb, u64 ino, u32 gen)) | |
909 | { | |
910 | struct inode *inode = NULL; | |
911 | ||
912 | if (fh_len <= 2) | |
913 | return NULL; | |
914 | ||
915 | switch (fh_type) { | |
916 | case FILEID_INO32_GEN_PARENT: | |
917 | inode = get_inode(sb, fid->i32.parent_ino, | |
918 | (fh_len > 3 ? fid->i32.parent_gen : 0)); | |
919 | break; | |
920 | } | |
921 | ||
4ea3ada2 | 922 | return d_obtain_alias(inode); |
2596110a CH |
923 | } |
924 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); | |
925 | ||
1b061d92 CH |
926 | /** |
927 | * generic_file_fsync - generic fsync implementation for simple filesystems | |
928 | * @file: file to synchronize | |
929 | * @datasync: only synchronize essential metadata if true | |
930 | * | |
931 | * This is a generic implementation of the fsync method for simple | |
932 | * filesystems which track all non-inode metadata in the buffers list | |
933 | * hanging off the address_space structure. | |
934 | */ | |
935 | int generic_file_fsync(struct file *file, int datasync) | |
d5aacad5 AV |
936 | { |
937 | struct writeback_control wbc = { | |
938 | .sync_mode = WB_SYNC_ALL, | |
939 | .nr_to_write = 0, /* metadata-only; caller takes care of data */ | |
940 | }; | |
7ea80859 | 941 | struct inode *inode = file->f_mapping->host; |
d5aacad5 AV |
942 | int err; |
943 | int ret; | |
944 | ||
945 | ret = sync_mapping_buffers(inode->i_mapping); | |
946 | if (!(inode->i_state & I_DIRTY)) | |
947 | return ret; | |
948 | if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) | |
949 | return ret; | |
950 | ||
951 | err = sync_inode(inode, &wbc); | |
952 | if (ret == 0) | |
953 | ret = err; | |
954 | return ret; | |
955 | } | |
1b061d92 CH |
956 | EXPORT_SYMBOL(generic_file_fsync); |
957 | ||
958 | /* | |
959 | * No-op implementation of ->fsync for in-memory filesystems. | |
960 | */ | |
961 | int noop_fsync(struct file *file, int datasync) | |
962 | { | |
963 | return 0; | |
964 | } | |
d5aacad5 | 965 | |
1da177e4 LT |
966 | EXPORT_SYMBOL(dcache_dir_close); |
967 | EXPORT_SYMBOL(dcache_dir_lseek); | |
968 | EXPORT_SYMBOL(dcache_dir_open); | |
969 | EXPORT_SYMBOL(dcache_readdir); | |
970 | EXPORT_SYMBOL(generic_read_dir); | |
971 | EXPORT_SYMBOL(get_sb_pseudo); | |
afddba49 NP |
972 | EXPORT_SYMBOL(simple_write_begin); |
973 | EXPORT_SYMBOL(simple_write_end); | |
1da177e4 LT |
974 | EXPORT_SYMBOL(simple_dir_inode_operations); |
975 | EXPORT_SYMBOL(simple_dir_operations); | |
976 | EXPORT_SYMBOL(simple_empty); | |
1da177e4 LT |
977 | EXPORT_SYMBOL(simple_fill_super); |
978 | EXPORT_SYMBOL(simple_getattr); | |
979 | EXPORT_SYMBOL(simple_link); | |
980 | EXPORT_SYMBOL(simple_lookup); | |
981 | EXPORT_SYMBOL(simple_pin_fs); | |
1da177e4 LT |
982 | EXPORT_SYMBOL(simple_readpage); |
983 | EXPORT_SYMBOL(simple_release_fs); | |
984 | EXPORT_SYMBOL(simple_rename); | |
985 | EXPORT_SYMBOL(simple_rmdir); | |
986 | EXPORT_SYMBOL(simple_statfs); | |
1b061d92 | 987 | EXPORT_SYMBOL(noop_fsync); |
1da177e4 LT |
988 | EXPORT_SYMBOL(simple_unlink); |
989 | EXPORT_SYMBOL(simple_read_from_buffer); | |
6a727b43 | 990 | EXPORT_SYMBOL(simple_write_to_buffer); |
93b07113 | 991 | EXPORT_SYMBOL(memory_read_from_buffer); |
76791ab2 | 992 | EXPORT_SYMBOL(simple_transaction_set); |
1da177e4 LT |
993 | EXPORT_SYMBOL(simple_transaction_get); |
994 | EXPORT_SYMBOL(simple_transaction_read); | |
995 | EXPORT_SYMBOL(simple_transaction_release); | |
acaefc25 | 996 | EXPORT_SYMBOL_GPL(simple_attr_open); |
74bedc4d | 997 | EXPORT_SYMBOL_GPL(simple_attr_release); |
acaefc25 AB |
998 | EXPORT_SYMBOL_GPL(simple_attr_read); |
999 | EXPORT_SYMBOL_GPL(simple_attr_write); |