3 * Library for filesystems writers.
6 #include <linux/module.h>
7 #include <linux/pagemap.h>
8 #include <linux/mount.h>
10 #include <asm/uaccess.h>
12 int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
15 struct inode *inode = dentry->d_inode;
16 generic_fillattr(inode, stat);
17 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
21 int simple_statfs(struct super_block *sb, struct kstatfs *buf)
23 buf->f_type = sb->s_magic;
24 buf->f_bsize = PAGE_CACHE_SIZE;
25 buf->f_namelen = NAME_MAX;
30 * Retaining negative dentries for an in-memory filesystem just wastes
31 * memory and lookup time: arrange for them to be deleted immediately.
33 static int simple_delete_dentry(struct dentry *dentry)
39 * Lookup the data. This is trivial - if the dentry didn't already
40 * exist, we know it is negative. Set d_op to delete negative dentries.
42 struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
44 static struct dentry_operations simple_dentry_operations = {
45 .d_delete = simple_delete_dentry,
48 if (dentry->d_name.len > NAME_MAX)
49 return ERR_PTR(-ENAMETOOLONG);
50 dentry->d_op = &simple_dentry_operations;
55 int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
60 int dcache_dir_open(struct inode *inode, struct file *file)
62 static struct qstr cursor_name = {.len = 1, .name = "."};
64 file->private_data = d_alloc(file->f_dentry, &cursor_name);
66 return file->private_data ? 0 : -ENOMEM;
69 int dcache_dir_close(struct inode *inode, struct file *file)
71 dput(file->private_data);
75 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
77 mutex_lock(&file->f_dentry->d_inode->i_mutex);
80 offset += file->f_pos;
85 mutex_unlock(&file->f_dentry->d_inode->i_mutex);
88 if (offset != file->f_pos) {
90 if (file->f_pos >= 2) {
92 struct dentry *cursor = file->private_data;
93 loff_t n = file->f_pos - 2;
95 spin_lock(&dcache_lock);
96 list_del(&cursor->d_u.d_child);
97 p = file->f_dentry->d_subdirs.next;
98 while (n && p != &file->f_dentry->d_subdirs) {
100 next = list_entry(p, struct dentry, d_u.d_child);
101 if (!d_unhashed(next) && next->d_inode)
105 list_add_tail(&cursor->d_u.d_child, p);
106 spin_unlock(&dcache_lock);
109 mutex_unlock(&file->f_dentry->d_inode->i_mutex);
113 /* Relationship between i_mode and the DT_xxx types */
114 static inline unsigned char dt_type(struct inode *inode)
116 return (inode->i_mode >> 12) & 15;
120 * Directory is locked and all positive dentries in it are safe, since
121 * for ramfs-type trees they can't go away without unlink() or rmdir(),
122 * both impossible due to the lock on directory.
125 static inline int do_dcache_readdir_filter(struct file * filp,
126 void * dirent, filldir_t filldir, int (*filter)(struct dentry *dentry))
128 struct dentry *dentry = filp->f_dentry;
129 struct dentry *cursor = filp->private_data;
130 struct list_head *p, *q = &cursor->d_u.d_child;
136 ino = dentry->d_inode->i_ino;
137 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
143 ino = parent_ino(dentry);
144 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
150 spin_lock(&dcache_lock);
151 if (filp->f_pos == 2) {
153 list_add(q, &dentry->d_subdirs);
155 for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
157 next = list_entry(p, struct dentry, d_u.d_child);
158 if (d_unhashed(next) || !next->d_inode)
160 if (filter && !filter(next))
163 spin_unlock(&dcache_lock);
164 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)
166 spin_lock(&dcache_lock);
167 /* next is still alive */
173 spin_unlock(&dcache_lock);
178 int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
180 return do_dcache_readdir_filter(filp, dirent, filldir, NULL);
183 int dcache_readdir_filter(struct file * filp, void * dirent, filldir_t filldir,
184 int (*filter)(struct dentry *))
186 return do_dcache_readdir_filter(filp, dirent, filldir, filter);
190 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
195 struct file_operations simple_dir_operations = {
196 .open = dcache_dir_open,
197 .release = dcache_dir_close,
198 .llseek = dcache_dir_lseek,
199 .read = generic_read_dir,
200 .readdir = dcache_readdir,
201 .fsync = simple_sync_file,
204 struct inode_operations simple_dir_inode_operations = {
205 .lookup = simple_lookup,
209 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
210 * will never be mountable)
213 get_sb_pseudo(struct file_system_type *fs_type, char *name,
214 struct super_operations *ops, unsigned long magic)
216 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
217 static struct super_operations default_ops = {.statfs = simple_statfs};
218 struct dentry *dentry;
220 struct qstr d_name = {.name = name, .len = strlen(name)};
225 s->s_flags = MS_NOUSER;
226 s->s_maxbytes = ~0ULL;
227 s->s_blocksize = 1024;
228 s->s_blocksize_bits = 10;
230 s->s_op = ops ? ops : &default_ops;
235 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
236 root->i_uid = root->i_gid = 0;
237 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
238 dentry = d_alloc(NULL, &d_name);
244 dentry->d_parent = dentry;
245 d_instantiate(dentry, root);
247 s->s_flags |= MS_ACTIVE;
251 up_write(&s->s_umount);
253 return ERR_PTR(-ENOMEM);
256 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
258 struct inode *inode = old_dentry->d_inode;
260 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
262 atomic_inc(&inode->i_count);
264 d_instantiate(dentry, inode);
268 static inline int simple_positive(struct dentry *dentry)
270 return dentry->d_inode && !d_unhashed(dentry);
273 int simple_empty(struct dentry *dentry)
275 struct dentry *child;
278 spin_lock(&dcache_lock);
279 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
280 if (simple_positive(child))
284 spin_unlock(&dcache_lock);
288 int simple_unlink(struct inode *dir, struct dentry *dentry)
290 struct inode *inode = dentry->d_inode;
292 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
298 int simple_rmdir(struct inode *dir, struct dentry *dentry)
300 if (!simple_empty(dentry))
303 dentry->d_inode->i_nlink--;
304 simple_unlink(dir, dentry);
309 int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
310 struct inode *new_dir, struct dentry *new_dentry)
312 struct inode *inode = old_dentry->d_inode;
313 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
315 if (!simple_empty(new_dentry))
318 if (new_dentry->d_inode) {
319 simple_unlink(new_dir, new_dentry);
322 } else if (they_are_dirs) {
327 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
328 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
333 int simple_readpage(struct file *file, struct page *page)
337 if (PageUptodate(page))
340 kaddr = kmap_atomic(page, KM_USER0);
341 memset(kaddr, 0, PAGE_CACHE_SIZE);
342 kunmap_atomic(kaddr, KM_USER0);
343 flush_dcache_page(page);
344 SetPageUptodate(page);
350 int simple_prepare_write(struct file *file, struct page *page,
351 unsigned from, unsigned to)
353 if (!PageUptodate(page)) {
354 if (to - from != PAGE_CACHE_SIZE) {
355 void *kaddr = kmap_atomic(page, KM_USER0);
356 memset(kaddr, 0, from);
357 memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
358 flush_dcache_page(page);
359 kunmap_atomic(kaddr, KM_USER0);
361 SetPageUptodate(page);
366 int simple_commit_write(struct file *file, struct page *page,
367 unsigned offset, unsigned to)
369 struct inode *inode = page->mapping->host;
370 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
373 * No need to use i_size_read() here, the i_size
374 * cannot change under us because we hold the i_mutex.
376 if (pos > inode->i_size)
377 i_size_write(inode, pos);
378 set_page_dirty(page);
382 int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
384 static struct super_operations s_ops = {.statfs = simple_statfs};
387 struct dentry *dentry;
390 s->s_blocksize = PAGE_CACHE_SIZE;
391 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
396 inode = new_inode(s);
399 inode->i_mode = S_IFDIR | 0755;
400 inode->i_uid = inode->i_gid = 0;
401 inode->i_blksize = PAGE_CACHE_SIZE;
403 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
404 inode->i_op = &simple_dir_inode_operations;
405 inode->i_fop = &simple_dir_operations;
407 root = d_alloc_root(inode);
412 for (i = 0; !files->name || files->name[0]; i++, files++) {
415 dentry = d_alloc_name(root, files->name);
418 inode = new_inode(s);
421 inode->i_mode = S_IFREG | files->mode;
422 inode->i_uid = inode->i_gid = 0;
423 inode->i_blksize = PAGE_CACHE_SIZE;
425 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
426 inode->i_fop = files->ops;
428 d_add(dentry, inode);
438 static DEFINE_SPINLOCK(pin_fs_lock);
440 int simple_pin_fs(char *name, struct vfsmount **mount, int *count)
442 struct vfsmount *mnt = NULL;
443 spin_lock(&pin_fs_lock);
444 if (unlikely(!*mount)) {
445 spin_unlock(&pin_fs_lock);
446 mnt = do_kern_mount(name, 0, name, NULL);
449 spin_lock(&pin_fs_lock);
455 spin_unlock(&pin_fs_lock);
460 void simple_release_fs(struct vfsmount **mount, int *count)
462 struct vfsmount *mnt;
463 spin_lock(&pin_fs_lock);
467 spin_unlock(&pin_fs_lock);
471 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
472 const void *from, size_t available)
477 if (pos >= available)
479 if (count > available - pos)
480 count = available - pos;
481 if (copy_to_user(to, from + pos, count))
488 * Transaction based IO.
489 * The file expects a single write which triggers the transaction, and then
490 * possibly a read which collects the result - which is stored in a
493 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
495 struct simple_transaction_argresp *ar;
496 static DEFINE_SPINLOCK(simple_transaction_lock);
498 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
499 return ERR_PTR(-EFBIG);
501 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
503 return ERR_PTR(-ENOMEM);
505 spin_lock(&simple_transaction_lock);
507 /* only one write allowed per open */
508 if (file->private_data) {
509 spin_unlock(&simple_transaction_lock);
510 free_page((unsigned long)ar);
511 return ERR_PTR(-EBUSY);
514 file->private_data = ar;
516 spin_unlock(&simple_transaction_lock);
518 if (copy_from_user(ar->data, buf, size))
519 return ERR_PTR(-EFAULT);
524 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
526 struct simple_transaction_argresp *ar = file->private_data;
530 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
533 int simple_transaction_release(struct inode *inode, struct file *file)
535 free_page((unsigned long)file->private_data);
539 /* Simple attribute files */
543 void (*set)(void *, u64);
544 char get_buf[24]; /* enough to store a u64 and "\n\0" */
547 const char *fmt; /* format for read operation */
548 struct semaphore sem; /* protects access to these buffers */
551 /* simple_attr_open is called by an actual attribute open file operation
552 * to set the attribute specific access operations. */
553 int simple_attr_open(struct inode *inode, struct file *file,
554 u64 (*get)(void *), void (*set)(void *, u64),
557 struct simple_attr *attr;
559 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
565 attr->data = inode->u.generic_ip;
567 init_MUTEX(&attr->sem);
569 file->private_data = attr;
571 return nonseekable_open(inode, file);
574 int simple_attr_close(struct inode *inode, struct file *file)
576 kfree(file->private_data);
580 /* read from the buffer that is filled with the get function */
581 ssize_t simple_attr_read(struct file *file, char __user *buf,
582 size_t len, loff_t *ppos)
584 struct simple_attr *attr;
588 attr = file->private_data;
594 if (*ppos) /* continued read */
595 size = strlen(attr->get_buf);
596 else /* first read */
597 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
599 (unsigned long long)attr->get(attr->data));
601 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
606 /* interpret the buffer as a number to call the set function with */
607 ssize_t simple_attr_write(struct file *file, const char __user *buf,
608 size_t len, loff_t *ppos)
610 struct simple_attr *attr;
615 attr = file->private_data;
622 size = min(sizeof(attr->set_buf) - 1, len);
623 if (copy_from_user(attr->set_buf, buf, size))
626 ret = len; /* claim we got the whole input */
627 attr->set_buf[size] = '\0';
628 val = simple_strtol(attr->set_buf, NULL, 0);
629 attr->set(attr->data, val);
635 EXPORT_SYMBOL(dcache_dir_close);
636 EXPORT_SYMBOL(dcache_dir_lseek);
637 EXPORT_SYMBOL(dcache_dir_open);
638 EXPORT_SYMBOL(dcache_readdir);
639 EXPORT_SYMBOL(dcache_readdir_filter);
640 EXPORT_SYMBOL(generic_read_dir);
641 EXPORT_SYMBOL(get_sb_pseudo);
642 EXPORT_SYMBOL(simple_commit_write);
643 EXPORT_SYMBOL(simple_dir_inode_operations);
644 EXPORT_SYMBOL(simple_dir_operations);
645 EXPORT_SYMBOL(simple_empty);
646 EXPORT_SYMBOL(d_alloc_name);
647 EXPORT_SYMBOL(simple_fill_super);
648 EXPORT_SYMBOL(simple_getattr);
649 EXPORT_SYMBOL(simple_link);
650 EXPORT_SYMBOL(simple_lookup);
651 EXPORT_SYMBOL(simple_pin_fs);
652 EXPORT_SYMBOL(simple_prepare_write);
653 EXPORT_SYMBOL(simple_readpage);
654 EXPORT_SYMBOL(simple_release_fs);
655 EXPORT_SYMBOL(simple_rename);
656 EXPORT_SYMBOL(simple_rmdir);
657 EXPORT_SYMBOL(simple_statfs);
658 EXPORT_SYMBOL(simple_sync_file);
659 EXPORT_SYMBOL(simple_unlink);
660 EXPORT_SYMBOL(simple_read_from_buffer);
661 EXPORT_SYMBOL(simple_transaction_get);
662 EXPORT_SYMBOL(simple_transaction_read);
663 EXPORT_SYMBOL(simple_transaction_release);
664 EXPORT_SYMBOL_GPL(simple_attr_open);
665 EXPORT_SYMBOL_GPL(simple_attr_close);
666 EXPORT_SYMBOL_GPL(simple_attr_read);
667 EXPORT_SYMBOL_GPL(simple_attr_write);