blob: 4fdeaceb892cb83d0206f2024f1bbc229dba1192 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Ingo Molnar7cf34c72006-03-23 03:00:36 -080010#include <linux/mutex.h>
11
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <asm/uaccess.h>
13
14int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
15 struct kstat *stat)
16{
17 struct inode *inode = dentry->d_inode;
18 generic_fillattr(inode, stat);
19 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
20 return 0;
21}
22
23int simple_statfs(struct super_block *sb, struct kstatfs *buf)
24{
25 buf->f_type = sb->s_magic;
26 buf->f_bsize = PAGE_CACHE_SIZE;
27 buf->f_namelen = NAME_MAX;
28 return 0;
29}
30
31/*
32 * Retaining negative dentries for an in-memory filesystem just wastes
33 * memory and lookup time: arrange for them to be deleted immediately.
34 */
35static int simple_delete_dentry(struct dentry *dentry)
36{
37 return 1;
38}
39
40/*
41 * Lookup the data. This is trivial - if the dentry didn't already
42 * exist, we know it is negative. Set d_op to delete negative dentries.
43 */
44struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
45{
46 static struct dentry_operations simple_dentry_operations = {
47 .d_delete = simple_delete_dentry,
48 };
49
50 if (dentry->d_name.len > NAME_MAX)
51 return ERR_PTR(-ENAMETOOLONG);
52 dentry->d_op = &simple_dentry_operations;
53 d_add(dentry, NULL);
54 return NULL;
55}
56
57int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
58{
59 return 0;
60}
61
62int dcache_dir_open(struct inode *inode, struct file *file)
63{
64 static struct qstr cursor_name = {.len = 1, .name = "."};
65
66 file->private_data = d_alloc(file->f_dentry, &cursor_name);
67
68 return file->private_data ? 0 : -ENOMEM;
69}
70
71int dcache_dir_close(struct inode *inode, struct file *file)
72{
73 dput(file->private_data);
74 return 0;
75}
76
77loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
78{
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080079 mutex_lock(&file->f_dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 switch (origin) {
81 case 1:
82 offset += file->f_pos;
83 case 0:
84 if (offset >= 0)
85 break;
86 default:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080087 mutex_unlock(&file->f_dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 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);
Eric Dumazet5160ee62006-01-08 01:03:32 -080098 list_del(&cursor->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 p = file->f_dentry->d_subdirs.next;
100 while (n && p != &file->f_dentry->d_subdirs) {
101 struct dentry *next;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800102 next = list_entry(p, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 if (!d_unhashed(next) && next->d_inode)
104 n--;
105 p = p->next;
106 }
Eric Dumazet5160ee62006-01-08 01:03:32 -0800107 list_add_tail(&cursor->d_u.d_child, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 spin_unlock(&dcache_lock);
109 }
110 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800111 mutex_unlock(&file->f_dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 return offset;
113}
114
115/* Relationship between i_mode and the DT_xxx types */
116static 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
127int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
128{
129 struct dentry *dentry = filp->f_dentry;
130 struct dentry *cursor = filp->private_data;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800131 struct list_head *p, *q = &cursor->d_u.d_child;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 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);
152 if (filp->f_pos == 2) {
153 list_del(q);
154 list_add(q, &dentry->d_subdirs);
155 }
156 for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
157 struct dentry *next;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800158 next = list_entry(p, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 if (d_unhashed(next) || !next->d_inode)
160 continue;
161
162 spin_unlock(&dcache_lock);
163 if (filldir(dirent, next->d_name.name, next->d_name.len, filp->f_pos, next->d_inode->i_ino, dt_type(next->d_inode)) < 0)
164 return 0;
165 spin_lock(&dcache_lock);
166 /* next is still alive */
167 list_del(q);
168 list_add(q, p);
169 p = q;
170 filp->f_pos++;
171 }
172 spin_unlock(&dcache_lock);
173 }
174 return 0;
175}
176
177ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
178{
179 return -EISDIR;
180}
181
182struct file_operations simple_dir_operations = {
183 .open = dcache_dir_open,
184 .release = dcache_dir_close,
185 .llseek = dcache_dir_lseek,
186 .read = generic_read_dir,
187 .readdir = dcache_readdir,
Hugh Dickins8ae0b772005-06-25 14:55:41 -0700188 .fsync = simple_sync_file,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189};
190
191struct inode_operations simple_dir_inode_operations = {
192 .lookup = simple_lookup,
193};
194
195/*
196 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
197 * will never be mountable)
198 */
199struct super_block *
200get_sb_pseudo(struct file_system_type *fs_type, char *name,
201 struct super_operations *ops, unsigned long magic)
202{
203 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
204 static struct super_operations default_ops = {.statfs = simple_statfs};
205 struct dentry *dentry;
206 struct inode *root;
207 struct qstr d_name = {.name = name, .len = strlen(name)};
208
209 if (IS_ERR(s))
210 return s;
211
212 s->s_flags = MS_NOUSER;
213 s->s_maxbytes = ~0ULL;
214 s->s_blocksize = 1024;
215 s->s_blocksize_bits = 10;
216 s->s_magic = magic;
217 s->s_op = ops ? ops : &default_ops;
218 s->s_time_gran = 1;
219 root = new_inode(s);
220 if (!root)
221 goto Enomem;
222 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
223 root->i_uid = root->i_gid = 0;
224 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
225 dentry = d_alloc(NULL, &d_name);
226 if (!dentry) {
227 iput(root);
228 goto Enomem;
229 }
230 dentry->d_sb = s;
231 dentry->d_parent = dentry;
232 d_instantiate(dentry, root);
233 s->s_root = dentry;
234 s->s_flags |= MS_ACTIVE;
235 return s;
236
237Enomem:
238 up_write(&s->s_umount);
239 deactivate_super(s);
240 return ERR_PTR(-ENOMEM);
241}
242
243int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
244{
245 struct inode *inode = old_dentry->d_inode;
246
247 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
248 inode->i_nlink++;
249 atomic_inc(&inode->i_count);
250 dget(dentry);
251 d_instantiate(dentry, inode);
252 return 0;
253}
254
255static inline int simple_positive(struct dentry *dentry)
256{
257 return dentry->d_inode && !d_unhashed(dentry);
258}
259
260int simple_empty(struct dentry *dentry)
261{
262 struct dentry *child;
263 int ret = 0;
264
265 spin_lock(&dcache_lock);
Eric Dumazet5160ee62006-01-08 01:03:32 -0800266 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 if (simple_positive(child))
268 goto out;
269 ret = 1;
270out:
271 spin_unlock(&dcache_lock);
272 return ret;
273}
274
275int simple_unlink(struct inode *dir, struct dentry *dentry)
276{
277 struct inode *inode = dentry->d_inode;
278
279 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
280 inode->i_nlink--;
281 dput(dentry);
282 return 0;
283}
284
285int simple_rmdir(struct inode *dir, struct dentry *dentry)
286{
287 if (!simple_empty(dentry))
288 return -ENOTEMPTY;
289
290 dentry->d_inode->i_nlink--;
291 simple_unlink(dir, dentry);
292 dir->i_nlink--;
293 return 0;
294}
295
296int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
297 struct inode *new_dir, struct dentry *new_dentry)
298{
299 struct inode *inode = old_dentry->d_inode;
300 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
301
302 if (!simple_empty(new_dentry))
303 return -ENOTEMPTY;
304
305 if (new_dentry->d_inode) {
306 simple_unlink(new_dir, new_dentry);
307 if (they_are_dirs)
308 old_dir->i_nlink--;
309 } else if (they_are_dirs) {
310 old_dir->i_nlink--;
311 new_dir->i_nlink++;
312 }
313
314 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
315 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
316
317 return 0;
318}
319
320int simple_readpage(struct file *file, struct page *page)
321{
322 void *kaddr;
323
324 if (PageUptodate(page))
325 goto out;
326
327 kaddr = kmap_atomic(page, KM_USER0);
328 memset(kaddr, 0, PAGE_CACHE_SIZE);
329 kunmap_atomic(kaddr, KM_USER0);
330 flush_dcache_page(page);
331 SetPageUptodate(page);
332out:
333 unlock_page(page);
334 return 0;
335}
336
337int simple_prepare_write(struct file *file, struct page *page,
338 unsigned from, unsigned to)
339{
340 if (!PageUptodate(page)) {
341 if (to - from != PAGE_CACHE_SIZE) {
342 void *kaddr = kmap_atomic(page, KM_USER0);
343 memset(kaddr, 0, from);
344 memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
345 flush_dcache_page(page);
346 kunmap_atomic(kaddr, KM_USER0);
347 }
348 SetPageUptodate(page);
349 }
350 return 0;
351}
352
353int simple_commit_write(struct file *file, struct page *page,
354 unsigned offset, unsigned to)
355{
356 struct inode *inode = page->mapping->host;
357 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
358
359 /*
360 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800361 * cannot change under us because we hold the i_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 */
363 if (pos > inode->i_size)
364 i_size_write(inode, pos);
365 set_page_dirty(page);
366 return 0;
367}
368
369int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
370{
371 static struct super_operations s_ops = {.statfs = simple_statfs};
372 struct inode *inode;
373 struct dentry *root;
374 struct dentry *dentry;
375 int i;
376
377 s->s_blocksize = PAGE_CACHE_SIZE;
378 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
379 s->s_magic = magic;
380 s->s_op = &s_ops;
381 s->s_time_gran = 1;
382
383 inode = new_inode(s);
384 if (!inode)
385 return -ENOMEM;
386 inode->i_mode = S_IFDIR | 0755;
387 inode->i_uid = inode->i_gid = 0;
388 inode->i_blksize = PAGE_CACHE_SIZE;
389 inode->i_blocks = 0;
390 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
391 inode->i_op = &simple_dir_inode_operations;
392 inode->i_fop = &simple_dir_operations;
Vincent Hanquez7656f322006-02-03 03:04:48 -0800393 inode->i_nlink = 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 root = d_alloc_root(inode);
395 if (!root) {
396 iput(inode);
397 return -ENOMEM;
398 }
399 for (i = 0; !files->name || files->name[0]; i++, files++) {
400 if (!files->name)
401 continue;
402 dentry = d_alloc_name(root, files->name);
403 if (!dentry)
404 goto out;
405 inode = new_inode(s);
406 if (!inode)
407 goto out;
408 inode->i_mode = S_IFREG | files->mode;
409 inode->i_uid = inode->i_gid = 0;
410 inode->i_blksize = PAGE_CACHE_SIZE;
411 inode->i_blocks = 0;
412 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
413 inode->i_fop = files->ops;
414 inode->i_ino = i;
415 d_add(dentry, inode);
416 }
417 s->s_root = root;
418 return 0;
419out:
420 d_genocide(root);
421 dput(root);
422 return -ENOMEM;
423}
424
425static DEFINE_SPINLOCK(pin_fs_lock);
426
427int simple_pin_fs(char *name, struct vfsmount **mount, int *count)
428{
429 struct vfsmount *mnt = NULL;
430 spin_lock(&pin_fs_lock);
431 if (unlikely(!*mount)) {
432 spin_unlock(&pin_fs_lock);
433 mnt = do_kern_mount(name, 0, name, NULL);
434 if (IS_ERR(mnt))
435 return PTR_ERR(mnt);
436 spin_lock(&pin_fs_lock);
437 if (!*mount)
438 *mount = mnt;
439 }
440 mntget(*mount);
441 ++*count;
442 spin_unlock(&pin_fs_lock);
443 mntput(mnt);
444 return 0;
445}
446
447void simple_release_fs(struct vfsmount **mount, int *count)
448{
449 struct vfsmount *mnt;
450 spin_lock(&pin_fs_lock);
451 mnt = *mount;
452 if (!--*count)
453 *mount = NULL;
454 spin_unlock(&pin_fs_lock);
455 mntput(mnt);
456}
457
458ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
459 const void *from, size_t available)
460{
461 loff_t pos = *ppos;
462 if (pos < 0)
463 return -EINVAL;
464 if (pos >= available)
465 return 0;
466 if (count > available - pos)
467 count = available - pos;
468 if (copy_to_user(to, from + pos, count))
469 return -EFAULT;
470 *ppos = pos + count;
471 return count;
472}
473
474/*
475 * Transaction based IO.
476 * The file expects a single write which triggers the transaction, and then
477 * possibly a read which collects the result - which is stored in a
478 * file-local buffer.
479 */
480char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
481{
482 struct simple_transaction_argresp *ar;
483 static DEFINE_SPINLOCK(simple_transaction_lock);
484
485 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
486 return ERR_PTR(-EFBIG);
487
488 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
489 if (!ar)
490 return ERR_PTR(-ENOMEM);
491
492 spin_lock(&simple_transaction_lock);
493
494 /* only one write allowed per open */
495 if (file->private_data) {
496 spin_unlock(&simple_transaction_lock);
497 free_page((unsigned long)ar);
498 return ERR_PTR(-EBUSY);
499 }
500
501 file->private_data = ar;
502
503 spin_unlock(&simple_transaction_lock);
504
505 if (copy_from_user(ar->data, buf, size))
506 return ERR_PTR(-EFAULT);
507
508 return ar->data;
509}
510
511ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
512{
513 struct simple_transaction_argresp *ar = file->private_data;
514
515 if (!ar)
516 return 0;
517 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
518}
519
520int simple_transaction_release(struct inode *inode, struct file *file)
521{
522 free_page((unsigned long)file->private_data);
523 return 0;
524}
525
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200526/* Simple attribute files */
527
528struct simple_attr {
529 u64 (*get)(void *);
530 void (*set)(void *, u64);
531 char get_buf[24]; /* enough to store a u64 and "\n\0" */
532 char set_buf[24];
533 void *data;
534 const char *fmt; /* format for read operation */
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800535 struct mutex mutex; /* protects access to these buffers */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200536};
537
538/* simple_attr_open is called by an actual attribute open file operation
539 * to set the attribute specific access operations. */
540int simple_attr_open(struct inode *inode, struct file *file,
541 u64 (*get)(void *), void (*set)(void *, u64),
542 const char *fmt)
543{
544 struct simple_attr *attr;
545
546 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
547 if (!attr)
548 return -ENOMEM;
549
550 attr->get = get;
551 attr->set = set;
552 attr->data = inode->u.generic_ip;
553 attr->fmt = fmt;
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800554 mutex_init(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200555
556 file->private_data = attr;
557
558 return nonseekable_open(inode, file);
559}
560
561int simple_attr_close(struct inode *inode, struct file *file)
562{
563 kfree(file->private_data);
564 return 0;
565}
566
567/* read from the buffer that is filled with the get function */
568ssize_t simple_attr_read(struct file *file, char __user *buf,
569 size_t len, loff_t *ppos)
570{
571 struct simple_attr *attr;
572 size_t size;
573 ssize_t ret;
574
575 attr = file->private_data;
576
577 if (!attr->get)
578 return -EACCES;
579
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800580 mutex_lock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200581 if (*ppos) /* continued read */
582 size = strlen(attr->get_buf);
583 else /* first read */
584 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
585 attr->fmt,
586 (unsigned long long)attr->get(attr->data));
587
588 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800589 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200590 return ret;
591}
592
593/* interpret the buffer as a number to call the set function with */
594ssize_t simple_attr_write(struct file *file, const char __user *buf,
595 size_t len, loff_t *ppos)
596{
597 struct simple_attr *attr;
598 u64 val;
599 size_t size;
600 ssize_t ret;
601
602 attr = file->private_data;
603
604 if (!attr->set)
605 return -EACCES;
606
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800607 mutex_lock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200608 ret = -EFAULT;
609 size = min(sizeof(attr->set_buf) - 1, len);
610 if (copy_from_user(attr->set_buf, buf, size))
611 goto out;
612
613 ret = len; /* claim we got the whole input */
614 attr->set_buf[size] = '\0';
615 val = simple_strtol(attr->set_buf, NULL, 0);
616 attr->set(attr->data, val);
617out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800618 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200619 return ret;
620}
621
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622EXPORT_SYMBOL(dcache_dir_close);
623EXPORT_SYMBOL(dcache_dir_lseek);
624EXPORT_SYMBOL(dcache_dir_open);
625EXPORT_SYMBOL(dcache_readdir);
626EXPORT_SYMBOL(generic_read_dir);
627EXPORT_SYMBOL(get_sb_pseudo);
628EXPORT_SYMBOL(simple_commit_write);
629EXPORT_SYMBOL(simple_dir_inode_operations);
630EXPORT_SYMBOL(simple_dir_operations);
631EXPORT_SYMBOL(simple_empty);
632EXPORT_SYMBOL(d_alloc_name);
633EXPORT_SYMBOL(simple_fill_super);
634EXPORT_SYMBOL(simple_getattr);
635EXPORT_SYMBOL(simple_link);
636EXPORT_SYMBOL(simple_lookup);
637EXPORT_SYMBOL(simple_pin_fs);
638EXPORT_SYMBOL(simple_prepare_write);
639EXPORT_SYMBOL(simple_readpage);
640EXPORT_SYMBOL(simple_release_fs);
641EXPORT_SYMBOL(simple_rename);
642EXPORT_SYMBOL(simple_rmdir);
643EXPORT_SYMBOL(simple_statfs);
644EXPORT_SYMBOL(simple_sync_file);
645EXPORT_SYMBOL(simple_unlink);
646EXPORT_SYMBOL(simple_read_from_buffer);
647EXPORT_SYMBOL(simple_transaction_get);
648EXPORT_SYMBOL(simple_transaction_read);
649EXPORT_SYMBOL(simple_transaction_release);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200650EXPORT_SYMBOL_GPL(simple_attr_open);
651EXPORT_SYMBOL_GPL(simple_attr_close);
652EXPORT_SYMBOL_GPL(simple_attr_read);
653EXPORT_SYMBOL_GPL(simple_attr_write);