Merge master.kernel.org:/home/rmk/linux-2.6-arm
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / libfs.c
blobd93842d3c0a0b66943a0491622e0793971d70de5
1 /*
2 * fs/libfs.c
3 * Library for filesystems writers.
4 */
6 #include <linux/module.h>
7 #include <linux/pagemap.h>
8 #include <linux/mount.h>
9 #include <linux/vfs.h>
10 #include <linux/mutex.h>
12 #include <asm/uaccess.h>
14 int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
15 struct kstat *stat)
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;
23 int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
25 buf->f_type = dentry->d_sb->s_magic;
26 buf->f_bsize = PAGE_CACHE_SIZE;
27 buf->f_namelen = NAME_MAX;
28 return 0;
32 * Retaining negative dentries for an in-memory filesystem just wastes
33 * memory and lookup time: arrange for them to be deleted immediately.
35 static int simple_delete_dentry(struct dentry *dentry)
37 return 1;
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.
44 struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
46 static struct dentry_operations simple_dentry_operations = {
47 .d_delete = simple_delete_dentry,
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;
57 int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
59 return 0;
62 int dcache_dir_open(struct inode *inode, struct file *file)
64 static struct qstr cursor_name = {.len = 1, .name = "."};
66 file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
68 return file->private_data ? 0 : -ENOMEM;
71 int dcache_dir_close(struct inode *inode, struct file *file)
73 dput(file->private_data);
74 return 0;
77 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
79 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
80 switch (origin) {
81 case 1:
82 offset += file->f_pos;
83 case 0:
84 if (offset >= 0)
85 break;
86 default:
87 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
88 return -EINVAL;
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;
97 spin_lock(&dcache_lock);
98 list_del(&cursor->d_u.d_child);
99 p = file->f_path.dentry->d_subdirs.next;
100 while (n && p != &file->f_path.dentry->d_subdirs) {
101 struct dentry *next;
102 next = list_entry(p, struct dentry, d_u.d_child);
103 if (!d_unhashed(next) && next->d_inode)
104 n--;
105 p = p->next;
107 list_add_tail(&cursor->d_u.d_child, p);
108 spin_unlock(&dcache_lock);
111 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
112 return offset;
115 /* Relationship between i_mode and the DT_xxx types */
116 static inline unsigned char dt_type(struct inode *inode)
118 return (inode->i_mode >> 12) & 15;
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.
127 int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
129 struct dentry *dentry = filp->f_path.dentry;
130 struct dentry *cursor = filp->private_data;
131 struct list_head *p, *q = &cursor->d_u.d_child;
132 ino_t ino;
133 int i = filp->f_pos;
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_move(q, &dentry->d_subdirs);
155 for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
156 struct dentry *next;
157 next = list_entry(p, struct dentry, d_u.d_child);
158 if (d_unhashed(next) || !next->d_inode)
159 continue;
161 spin_unlock(&dcache_lock);
162 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)
163 return 0;
164 spin_lock(&dcache_lock);
165 /* next is still alive */
166 list_move(q, p);
167 p = q;
168 filp->f_pos++;
170 spin_unlock(&dcache_lock);
172 return 0;
175 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
177 return -EISDIR;
180 const struct file_operations simple_dir_operations = {
181 .open = dcache_dir_open,
182 .release = dcache_dir_close,
183 .llseek = dcache_dir_lseek,
184 .read = generic_read_dir,
185 .readdir = dcache_readdir,
186 .fsync = simple_sync_file,
189 const struct inode_operations simple_dir_inode_operations = {
190 .lookup = simple_lookup,
193 static const struct super_operations simple_super_operations = {
194 .statfs = simple_statfs,
198 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
199 * will never be mountable)
201 int get_sb_pseudo(struct file_system_type *fs_type, char *name,
202 const struct super_operations *ops, unsigned long magic,
203 struct vfsmount *mnt)
205 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
206 struct dentry *dentry;
207 struct inode *root;
208 struct qstr d_name = {.name = name, .len = strlen(name)};
210 if (IS_ERR(s))
211 return PTR_ERR(s);
213 s->s_flags = MS_NOUSER;
214 s->s_maxbytes = ~0ULL;
215 s->s_blocksize = 1024;
216 s->s_blocksize_bits = 10;
217 s->s_magic = magic;
218 s->s_op = ops ? ops : &simple_super_operations;
219 s->s_time_gran = 1;
220 root = new_inode(s);
221 if (!root)
222 goto Enomem;
223 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
224 root->i_uid = root->i_gid = 0;
225 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
226 dentry = d_alloc(NULL, &d_name);
227 if (!dentry) {
228 iput(root);
229 goto Enomem;
231 dentry->d_sb = s;
232 dentry->d_parent = dentry;
233 d_instantiate(dentry, root);
234 s->s_root = dentry;
235 s->s_flags |= MS_ACTIVE;
236 return simple_set_mnt(mnt, s);
238 Enomem:
239 up_write(&s->s_umount);
240 deactivate_super(s);
241 return -ENOMEM;
244 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
246 struct inode *inode = old_dentry->d_inode;
248 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
249 inc_nlink(inode);
250 atomic_inc(&inode->i_count);
251 dget(dentry);
252 d_instantiate(dentry, inode);
253 return 0;
256 static inline int simple_positive(struct dentry *dentry)
258 return dentry->d_inode && !d_unhashed(dentry);
261 int simple_empty(struct dentry *dentry)
263 struct dentry *child;
264 int ret = 0;
266 spin_lock(&dcache_lock);
267 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
268 if (simple_positive(child))
269 goto out;
270 ret = 1;
271 out:
272 spin_unlock(&dcache_lock);
273 return ret;
276 int simple_unlink(struct inode *dir, struct dentry *dentry)
278 struct inode *inode = dentry->d_inode;
280 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
281 drop_nlink(inode);
282 dput(dentry);
283 return 0;
286 int simple_rmdir(struct inode *dir, struct dentry *dentry)
288 if (!simple_empty(dentry))
289 return -ENOTEMPTY;
291 drop_nlink(dentry->d_inode);
292 simple_unlink(dir, dentry);
293 drop_nlink(dir);
294 return 0;
297 int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
298 struct inode *new_dir, struct dentry *new_dentry)
300 struct inode *inode = old_dentry->d_inode;
301 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
303 if (!simple_empty(new_dentry))
304 return -ENOTEMPTY;
306 if (new_dentry->d_inode) {
307 simple_unlink(new_dir, new_dentry);
308 if (they_are_dirs)
309 drop_nlink(old_dir);
310 } else if (they_are_dirs) {
311 drop_nlink(old_dir);
312 inc_nlink(new_dir);
315 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
316 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
318 return 0;
321 int simple_readpage(struct file *file, struct page *page)
323 clear_highpage(page);
324 flush_dcache_page(page);
325 SetPageUptodate(page);
326 unlock_page(page);
327 return 0;
330 int simple_prepare_write(struct file *file, struct page *page,
331 unsigned from, unsigned to)
333 if (!PageUptodate(page)) {
334 if (to - from != PAGE_CACHE_SIZE) {
335 void *kaddr = kmap_atomic(page, KM_USER0);
336 memset(kaddr, 0, from);
337 memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
338 flush_dcache_page(page);
339 kunmap_atomic(kaddr, KM_USER0);
342 return 0;
345 int simple_commit_write(struct file *file, struct page *page,
346 unsigned from, unsigned to)
348 struct inode *inode = page->mapping->host;
349 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
351 if (!PageUptodate(page))
352 SetPageUptodate(page);
354 * No need to use i_size_read() here, the i_size
355 * cannot change under us because we hold the i_mutex.
357 if (pos > inode->i_size)
358 i_size_write(inode, pos);
359 set_page_dirty(page);
360 return 0;
363 int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
365 struct inode *inode;
366 struct dentry *root;
367 struct dentry *dentry;
368 int i;
370 s->s_blocksize = PAGE_CACHE_SIZE;
371 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
372 s->s_magic = magic;
373 s->s_op = &simple_super_operations;
374 s->s_time_gran = 1;
376 inode = new_inode(s);
377 if (!inode)
378 return -ENOMEM;
379 inode->i_mode = S_IFDIR | 0755;
380 inode->i_uid = inode->i_gid = 0;
381 inode->i_blocks = 0;
382 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
383 inode->i_op = &simple_dir_inode_operations;
384 inode->i_fop = &simple_dir_operations;
385 inode->i_nlink = 2;
386 root = d_alloc_root(inode);
387 if (!root) {
388 iput(inode);
389 return -ENOMEM;
391 for (i = 0; !files->name || files->name[0]; i++, files++) {
392 if (!files->name)
393 continue;
394 dentry = d_alloc_name(root, files->name);
395 if (!dentry)
396 goto out;
397 inode = new_inode(s);
398 if (!inode)
399 goto out;
400 inode->i_mode = S_IFREG | files->mode;
401 inode->i_uid = inode->i_gid = 0;
402 inode->i_blocks = 0;
403 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
404 inode->i_fop = files->ops;
405 inode->i_ino = i;
406 d_add(dentry, inode);
408 s->s_root = root;
409 return 0;
410 out:
411 d_genocide(root);
412 dput(root);
413 return -ENOMEM;
416 static DEFINE_SPINLOCK(pin_fs_lock);
418 int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
420 struct vfsmount *mnt = NULL;
421 spin_lock(&pin_fs_lock);
422 if (unlikely(!*mount)) {
423 spin_unlock(&pin_fs_lock);
424 mnt = vfs_kern_mount(type, 0, type->name, NULL);
425 if (IS_ERR(mnt))
426 return PTR_ERR(mnt);
427 spin_lock(&pin_fs_lock);
428 if (!*mount)
429 *mount = mnt;
431 mntget(*mount);
432 ++*count;
433 spin_unlock(&pin_fs_lock);
434 mntput(mnt);
435 return 0;
438 void simple_release_fs(struct vfsmount **mount, int *count)
440 struct vfsmount *mnt;
441 spin_lock(&pin_fs_lock);
442 mnt = *mount;
443 if (!--*count)
444 *mount = NULL;
445 spin_unlock(&pin_fs_lock);
446 mntput(mnt);
449 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
450 const void *from, size_t available)
452 loff_t pos = *ppos;
453 if (pos < 0)
454 return -EINVAL;
455 if (pos >= available)
456 return 0;
457 if (count > available - pos)
458 count = available - pos;
459 if (copy_to_user(to, from + pos, count))
460 return -EFAULT;
461 *ppos = pos + count;
462 return count;
466 * Transaction based IO.
467 * The file expects a single write which triggers the transaction, and then
468 * possibly a read which collects the result - which is stored in a
469 * file-local buffer.
471 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
473 struct simple_transaction_argresp *ar;
474 static DEFINE_SPINLOCK(simple_transaction_lock);
476 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
477 return ERR_PTR(-EFBIG);
479 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
480 if (!ar)
481 return ERR_PTR(-ENOMEM);
483 spin_lock(&simple_transaction_lock);
485 /* only one write allowed per open */
486 if (file->private_data) {
487 spin_unlock(&simple_transaction_lock);
488 free_page((unsigned long)ar);
489 return ERR_PTR(-EBUSY);
492 file->private_data = ar;
494 spin_unlock(&simple_transaction_lock);
496 if (copy_from_user(ar->data, buf, size))
497 return ERR_PTR(-EFAULT);
499 return ar->data;
502 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
504 struct simple_transaction_argresp *ar = file->private_data;
506 if (!ar)
507 return 0;
508 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
511 int simple_transaction_release(struct inode *inode, struct file *file)
513 free_page((unsigned long)file->private_data);
514 return 0;
517 /* Simple attribute files */
519 struct simple_attr {
520 u64 (*get)(void *);
521 void (*set)(void *, u64);
522 char get_buf[24]; /* enough to store a u64 and "\n\0" */
523 char set_buf[24];
524 void *data;
525 const char *fmt; /* format for read operation */
526 struct mutex mutex; /* protects access to these buffers */
529 /* simple_attr_open is called by an actual attribute open file operation
530 * to set the attribute specific access operations. */
531 int simple_attr_open(struct inode *inode, struct file *file,
532 u64 (*get)(void *), void (*set)(void *, u64),
533 const char *fmt)
535 struct simple_attr *attr;
537 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
538 if (!attr)
539 return -ENOMEM;
541 attr->get = get;
542 attr->set = set;
543 attr->data = inode->i_private;
544 attr->fmt = fmt;
545 mutex_init(&attr->mutex);
547 file->private_data = attr;
549 return nonseekable_open(inode, file);
552 int simple_attr_close(struct inode *inode, struct file *file)
554 kfree(file->private_data);
555 return 0;
558 /* read from the buffer that is filled with the get function */
559 ssize_t simple_attr_read(struct file *file, char __user *buf,
560 size_t len, loff_t *ppos)
562 struct simple_attr *attr;
563 size_t size;
564 ssize_t ret;
566 attr = file->private_data;
568 if (!attr->get)
569 return -EACCES;
571 mutex_lock(&attr->mutex);
572 if (*ppos) /* continued read */
573 size = strlen(attr->get_buf);
574 else /* first read */
575 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
576 attr->fmt,
577 (unsigned long long)attr->get(attr->data));
579 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
580 mutex_unlock(&attr->mutex);
581 return ret;
584 /* interpret the buffer as a number to call the set function with */
585 ssize_t simple_attr_write(struct file *file, const char __user *buf,
586 size_t len, loff_t *ppos)
588 struct simple_attr *attr;
589 u64 val;
590 size_t size;
591 ssize_t ret;
593 attr = file->private_data;
595 if (!attr->set)
596 return -EACCES;
598 mutex_lock(&attr->mutex);
599 ret = -EFAULT;
600 size = min(sizeof(attr->set_buf) - 1, len);
601 if (copy_from_user(attr->set_buf, buf, size))
602 goto out;
604 ret = len; /* claim we got the whole input */
605 attr->set_buf[size] = '\0';
606 val = simple_strtol(attr->set_buf, NULL, 0);
607 attr->set(attr->data, val);
608 out:
609 mutex_unlock(&attr->mutex);
610 return ret;
613 EXPORT_SYMBOL(dcache_dir_close);
614 EXPORT_SYMBOL(dcache_dir_lseek);
615 EXPORT_SYMBOL(dcache_dir_open);
616 EXPORT_SYMBOL(dcache_readdir);
617 EXPORT_SYMBOL(generic_read_dir);
618 EXPORT_SYMBOL(get_sb_pseudo);
619 EXPORT_SYMBOL(simple_commit_write);
620 EXPORT_SYMBOL(simple_dir_inode_operations);
621 EXPORT_SYMBOL(simple_dir_operations);
622 EXPORT_SYMBOL(simple_empty);
623 EXPORT_SYMBOL(d_alloc_name);
624 EXPORT_SYMBOL(simple_fill_super);
625 EXPORT_SYMBOL(simple_getattr);
626 EXPORT_SYMBOL(simple_link);
627 EXPORT_SYMBOL(simple_lookup);
628 EXPORT_SYMBOL(simple_pin_fs);
629 EXPORT_SYMBOL(simple_prepare_write);
630 EXPORT_SYMBOL(simple_readpage);
631 EXPORT_SYMBOL(simple_release_fs);
632 EXPORT_SYMBOL(simple_rename);
633 EXPORT_SYMBOL(simple_rmdir);
634 EXPORT_SYMBOL(simple_statfs);
635 EXPORT_SYMBOL(simple_sync_file);
636 EXPORT_SYMBOL(simple_unlink);
637 EXPORT_SYMBOL(simple_read_from_buffer);
638 EXPORT_SYMBOL(simple_transaction_get);
639 EXPORT_SYMBOL(simple_transaction_read);
640 EXPORT_SYMBOL(simple_transaction_release);
641 EXPORT_SYMBOL_GPL(simple_attr_open);
642 EXPORT_SYMBOL_GPL(simple_attr_close);
643 EXPORT_SYMBOL_GPL(simple_attr_read);
644 EXPORT_SYMBOL_GPL(simple_attr_write);