3 * Library for filesystems writers.
6 #include <linux/module.h>
7 #include <linux/pagemap.h>
8 #include <linux/mount.h>
10 #include <linux/mutex.h>
11 #include <linux/exportfs.h>
13 #include <asm/uaccess.h>
15 int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
18 struct inode *inode = dentry->d_inode;
19 generic_fillattr(inode, stat);
20 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
24 int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
26 buf->f_type = dentry->d_sb->s_magic;
27 buf->f_bsize = PAGE_CACHE_SIZE;
28 buf->f_namelen = NAME_MAX;
33 * Retaining negative dentries for an in-memory filesystem just wastes
34 * memory and lookup time: arrange for them to be deleted immediately.
36 static int simple_delete_dentry(struct dentry *dentry)
42 * Lookup the data. This is trivial - if the dentry didn't already
43 * exist, we know it is negative. Set d_op to delete negative dentries.
45 struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
47 static struct dentry_operations simple_dentry_operations = {
48 .d_delete = simple_delete_dentry,
51 if (dentry->d_name.len > NAME_MAX)
52 return ERR_PTR(-ENAMETOOLONG);
53 dentry->d_op = &simple_dentry_operations;
58 int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
63 int dcache_dir_open(struct inode *inode, struct file *file)
65 static struct qstr cursor_name = {.len = 1, .name = "."};
67 file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
69 return file->private_data ? 0 : -ENOMEM;
72 int dcache_dir_close(struct inode *inode, struct file *file)
74 dput(file->private_data);
78 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
80 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
83 offset += file->f_pos;
88 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
91 if (offset != file->f_pos) {
93 if (file->f_pos >= 2) {
95 struct dentry *cursor = file->private_data;
96 loff_t n = file->f_pos - 2;
98 spin_lock(&dcache_lock);
99 list_del(&cursor->d_u.d_child);
100 p = file->f_path.dentry->d_subdirs.next;
101 while (n && p != &file->f_path.dentry->d_subdirs) {
103 next = list_entry(p, struct dentry, d_u.d_child);
104 if (!d_unhashed(next) && next->d_inode)
108 list_add_tail(&cursor->d_u.d_child, p);
109 spin_unlock(&dcache_lock);
112 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
116 /* Relationship between i_mode and the DT_xxx types */
117 static inline unsigned char dt_type(struct inode *inode)
119 return (inode->i_mode >> 12) & 15;
123 * Directory is locked and all positive dentries in it are safe, since
124 * for ramfs-type trees they can't go away without unlink() or rmdir(),
125 * both impossible due to the lock on directory.
128 int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
130 struct dentry *dentry = filp->f_path.dentry;
131 struct dentry *cursor = filp->private_data;
132 struct list_head *p, *q = &cursor->d_u.d_child;
138 ino = dentry->d_inode->i_ino;
139 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
145 ino = parent_ino(dentry);
146 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
152 spin_lock(&dcache_lock);
153 if (filp->f_pos == 2)
154 list_move(q, &dentry->d_subdirs);
156 for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
158 next = list_entry(p, struct dentry, d_u.d_child);
159 if (d_unhashed(next) || !next->d_inode)
162 spin_unlock(&dcache_lock);
163 if (filldir(dirent, next->d_name.name,
164 next->d_name.len, filp->f_pos,
165 next->d_inode->i_ino,
166 dt_type(next->d_inode)) < 0)
168 spin_lock(&dcache_lock);
169 /* next is still alive */
174 spin_unlock(&dcache_lock);
179 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
184 const struct file_operations simple_dir_operations = {
185 .open = dcache_dir_open,
186 .release = dcache_dir_close,
187 .llseek = dcache_dir_lseek,
188 .read = generic_read_dir,
189 .readdir = dcache_readdir,
190 .fsync = simple_sync_file,
193 const struct inode_operations simple_dir_inode_operations = {
194 .lookup = simple_lookup,
197 static const struct super_operations simple_super_operations = {
198 .statfs = simple_statfs,
202 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
203 * will never be mountable)
205 int get_sb_pseudo(struct file_system_type *fs_type, char *name,
206 const struct super_operations *ops, unsigned long magic,
207 struct vfsmount *mnt)
209 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
210 struct dentry *dentry;
212 struct qstr d_name = {.name = name, .len = strlen(name)};
217 s->s_flags = MS_NOUSER;
218 s->s_maxbytes = ~0ULL;
219 s->s_blocksize = PAGE_SIZE;
220 s->s_blocksize_bits = PAGE_SHIFT;
222 s->s_op = ops ? ops : &simple_super_operations;
228 * since this is the first inode, make it number 1. New inodes created
229 * after this must take care not to collide with it (by passing
230 * max_reserved of 1 to iunique).
233 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
234 root->i_uid = root->i_gid = 0;
235 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
236 dentry = d_alloc(NULL, &d_name);
242 dentry->d_parent = dentry;
243 d_instantiate(dentry, root);
245 s->s_flags |= MS_ACTIVE;
246 return simple_set_mnt(mnt, s);
249 up_write(&s->s_umount);
254 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
256 struct inode *inode = old_dentry->d_inode;
258 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
260 atomic_inc(&inode->i_count);
262 d_instantiate(dentry, inode);
266 static inline int simple_positive(struct dentry *dentry)
268 return dentry->d_inode && !d_unhashed(dentry);
271 int simple_empty(struct dentry *dentry)
273 struct dentry *child;
276 spin_lock(&dcache_lock);
277 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
278 if (simple_positive(child))
282 spin_unlock(&dcache_lock);
286 int simple_unlink(struct inode *dir, struct dentry *dentry)
288 struct inode *inode = dentry->d_inode;
290 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
296 int simple_rmdir(struct inode *dir, struct dentry *dentry)
298 if (!simple_empty(dentry))
301 drop_nlink(dentry->d_inode);
302 simple_unlink(dir, dentry);
307 int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
308 struct inode *new_dir, struct dentry *new_dentry)
310 struct inode *inode = old_dentry->d_inode;
311 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
313 if (!simple_empty(new_dentry))
316 if (new_dentry->d_inode) {
317 simple_unlink(new_dir, new_dentry);
320 } else if (they_are_dirs) {
325 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
326 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
331 int simple_readpage(struct file *file, struct page *page)
333 clear_highpage(page);
334 flush_dcache_page(page);
335 SetPageUptodate(page);
340 int simple_prepare_write(struct file *file, struct page *page,
341 unsigned from, unsigned to)
343 if (!PageUptodate(page)) {
344 if (to - from != PAGE_CACHE_SIZE)
345 zero_user_segments(page,
347 to, PAGE_CACHE_SIZE);
352 int simple_write_begin(struct file *file, struct address_space *mapping,
353 loff_t pos, unsigned len, unsigned flags,
354 struct page **pagep, void **fsdata)
360 index = pos >> PAGE_CACHE_SHIFT;
361 from = pos & (PAGE_CACHE_SIZE - 1);
363 page = __grab_cache_page(mapping, index);
369 return simple_prepare_write(file, page, from, from+len);
372 static int simple_commit_write(struct file *file, struct page *page,
373 unsigned from, unsigned to)
375 struct inode *inode = page->mapping->host;
376 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
378 if (!PageUptodate(page))
379 SetPageUptodate(page);
381 * No need to use i_size_read() here, the i_size
382 * cannot change under us because we hold the i_mutex.
384 if (pos > inode->i_size)
385 i_size_write(inode, pos);
386 set_page_dirty(page);
390 int simple_write_end(struct file *file, struct address_space *mapping,
391 loff_t pos, unsigned len, unsigned copied,
392 struct page *page, void *fsdata)
394 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
396 /* zero the stale part of the page if we did a short copy */
398 void *kaddr = kmap_atomic(page, KM_USER0);
399 memset(kaddr + from + copied, 0, len - copied);
400 flush_dcache_page(page);
401 kunmap_atomic(kaddr, KM_USER0);
404 simple_commit_write(file, page, from, from+copied);
407 page_cache_release(page);
413 * the inodes created here are not hashed. If you use iunique to generate
414 * unique inode values later for this filesystem, then you must take care
415 * to pass it an appropriate max_reserved value to avoid collisions.
417 int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
421 struct dentry *dentry;
424 s->s_blocksize = PAGE_CACHE_SIZE;
425 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
427 s->s_op = &simple_super_operations;
430 inode = new_inode(s);
434 * because the root inode is 1, the files array must not contain an
438 inode->i_mode = S_IFDIR | 0755;
439 inode->i_uid = inode->i_gid = 0;
441 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
442 inode->i_op = &simple_dir_inode_operations;
443 inode->i_fop = &simple_dir_operations;
445 root = d_alloc_root(inode);
450 for (i = 0; !files->name || files->name[0]; i++, files++) {
454 /* warn if it tries to conflict with the root inode */
455 if (unlikely(i == 1))
456 printk(KERN_WARNING "%s: %s passed in a files array"
457 "with an index of 1!\n", __func__,
460 dentry = d_alloc_name(root, files->name);
463 inode = new_inode(s);
466 inode->i_mode = S_IFREG | files->mode;
467 inode->i_uid = inode->i_gid = 0;
469 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
470 inode->i_fop = files->ops;
472 d_add(dentry, inode);
482 static DEFINE_SPINLOCK(pin_fs_lock);
484 int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
486 struct vfsmount *mnt = NULL;
487 spin_lock(&pin_fs_lock);
488 if (unlikely(!*mount)) {
489 spin_unlock(&pin_fs_lock);
490 mnt = vfs_kern_mount(type, 0, type->name, NULL);
493 spin_lock(&pin_fs_lock);
499 spin_unlock(&pin_fs_lock);
504 void simple_release_fs(struct vfsmount **mount, int *count)
506 struct vfsmount *mnt;
507 spin_lock(&pin_fs_lock);
511 spin_unlock(&pin_fs_lock);
516 * simple_read_from_buffer - copy data from the buffer to user space
517 * @to: the user space buffer to read to
518 * @count: the maximum number of bytes to read
519 * @ppos: the current position in the buffer
520 * @from: the buffer to read from
521 * @available: the size of the buffer
523 * The simple_read_from_buffer() function reads up to @count bytes from the
524 * buffer @from at offset @ppos into the user space address starting at @to.
526 * On success, the number of bytes read is returned and the offset @ppos is
527 * advanced by this number, or negative value is returned on error.
529 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
530 const void *from, size_t available)
535 if (pos >= available)
537 if (count > available - pos)
538 count = available - pos;
539 if (copy_to_user(to, from + pos, count))
546 * memory_read_from_buffer - copy data from the buffer
547 * @to: the kernel space buffer to read to
548 * @count: the maximum number of bytes to read
549 * @ppos: the current position in the buffer
550 * @from: the buffer to read from
551 * @available: the size of the buffer
553 * The memory_read_from_buffer() function reads up to @count bytes from the
554 * buffer @from at offset @ppos into the kernel space address starting at @to.
556 * On success, the number of bytes read is returned and the offset @ppos is
557 * advanced by this number, or negative value is returned on error.
559 ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
560 const void *from, size_t available)
566 if (pos >= available)
568 if (count > available - pos)
569 count = available - pos;
570 memcpy(to, from + pos, count);
577 * Transaction based IO.
578 * The file expects a single write which triggers the transaction, and then
579 * possibly a read which collects the result - which is stored in a
582 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
584 struct simple_transaction_argresp *ar;
585 static DEFINE_SPINLOCK(simple_transaction_lock);
587 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
588 return ERR_PTR(-EFBIG);
590 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
592 return ERR_PTR(-ENOMEM);
594 spin_lock(&simple_transaction_lock);
596 /* only one write allowed per open */
597 if (file->private_data) {
598 spin_unlock(&simple_transaction_lock);
599 free_page((unsigned long)ar);
600 return ERR_PTR(-EBUSY);
603 file->private_data = ar;
605 spin_unlock(&simple_transaction_lock);
607 if (copy_from_user(ar->data, buf, size))
608 return ERR_PTR(-EFAULT);
613 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
615 struct simple_transaction_argresp *ar = file->private_data;
619 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
622 int simple_transaction_release(struct inode *inode, struct file *file)
624 free_page((unsigned long)file->private_data);
628 /* Simple attribute files */
631 int (*get)(void *, u64 *);
632 int (*set)(void *, u64);
633 char get_buf[24]; /* enough to store a u64 and "\n\0" */
636 const char *fmt; /* format for read operation */
637 struct mutex mutex; /* protects access to these buffers */
640 /* simple_attr_open is called by an actual attribute open file operation
641 * to set the attribute specific access operations. */
642 int simple_attr_open(struct inode *inode, struct file *file,
643 int (*get)(void *, u64 *), int (*set)(void *, u64),
646 struct simple_attr *attr;
648 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
654 attr->data = inode->i_private;
656 mutex_init(&attr->mutex);
658 file->private_data = attr;
660 return nonseekable_open(inode, file);
663 int simple_attr_release(struct inode *inode, struct file *file)
665 kfree(file->private_data);
669 /* read from the buffer that is filled with the get function */
670 ssize_t simple_attr_read(struct file *file, char __user *buf,
671 size_t len, loff_t *ppos)
673 struct simple_attr *attr;
677 attr = file->private_data;
682 ret = mutex_lock_interruptible(&attr->mutex);
686 if (*ppos) { /* continued read */
687 size = strlen(attr->get_buf);
688 } else { /* first read */
690 ret = attr->get(attr->data, &val);
694 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
695 attr->fmt, (unsigned long long)val);
698 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
700 mutex_unlock(&attr->mutex);
704 /* interpret the buffer as a number to call the set function with */
705 ssize_t simple_attr_write(struct file *file, const char __user *buf,
706 size_t len, loff_t *ppos)
708 struct simple_attr *attr;
713 attr = file->private_data;
717 ret = mutex_lock_interruptible(&attr->mutex);
722 size = min(sizeof(attr->set_buf) - 1, len);
723 if (copy_from_user(attr->set_buf, buf, size))
726 ret = len; /* claim we got the whole input */
727 attr->set_buf[size] = '\0';
728 val = simple_strtol(attr->set_buf, NULL, 0);
729 attr->set(attr->data, val);
731 mutex_unlock(&attr->mutex);
736 * This is what d_alloc_anon should have been. Once the exportfs
737 * argument transition has been finished I will update d_alloc_anon
738 * to this prototype and this wrapper will go away. --hch
740 static struct dentry *exportfs_d_alloc(struct inode *inode)
742 struct dentry *dentry;
747 return ERR_PTR(PTR_ERR(inode));
749 dentry = d_alloc_anon(inode);
752 dentry = ERR_PTR(-ENOMEM);
758 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
759 * @sb: filesystem to do the file handle conversion on
760 * @fid: file handle to convert
761 * @fh_len: length of the file handle in bytes
762 * @fh_type: type of file handle
763 * @get_inode: filesystem callback to retrieve inode
765 * This function decodes @fid as long as it has one of the well-known
766 * Linux filehandle types and calls @get_inode on it to retrieve the
767 * inode for the object specified in the file handle.
769 struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
770 int fh_len, int fh_type, struct inode *(*get_inode)
771 (struct super_block *sb, u64 ino, u32 gen))
773 struct inode *inode = NULL;
779 case FILEID_INO32_GEN:
780 case FILEID_INO32_GEN_PARENT:
781 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
785 return exportfs_d_alloc(inode);
787 EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
790 * generic_fh_to_dentry - generic helper for the fh_to_parent export operation
791 * @sb: filesystem to do the file handle conversion on
792 * @fid: file handle to convert
793 * @fh_len: length of the file handle in bytes
794 * @fh_type: type of file handle
795 * @get_inode: filesystem callback to retrieve inode
797 * This function decodes @fid as long as it has one of the well-known
798 * Linux filehandle types and calls @get_inode on it to retrieve the
799 * inode for the _parent_ object specified in the file handle if it
800 * is specified in the file handle, or NULL otherwise.
802 struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
803 int fh_len, int fh_type, struct inode *(*get_inode)
804 (struct super_block *sb, u64 ino, u32 gen))
806 struct inode *inode = NULL;
812 case FILEID_INO32_GEN_PARENT:
813 inode = get_inode(sb, fid->i32.parent_ino,
814 (fh_len > 3 ? fid->i32.parent_gen : 0));
818 return exportfs_d_alloc(inode);
820 EXPORT_SYMBOL_GPL(generic_fh_to_parent);
822 EXPORT_SYMBOL(dcache_dir_close);
823 EXPORT_SYMBOL(dcache_dir_lseek);
824 EXPORT_SYMBOL(dcache_dir_open);
825 EXPORT_SYMBOL(dcache_readdir);
826 EXPORT_SYMBOL(generic_read_dir);
827 EXPORT_SYMBOL(get_sb_pseudo);
828 EXPORT_SYMBOL(simple_write_begin);
829 EXPORT_SYMBOL(simple_write_end);
830 EXPORT_SYMBOL(simple_dir_inode_operations);
831 EXPORT_SYMBOL(simple_dir_operations);
832 EXPORT_SYMBOL(simple_empty);
833 EXPORT_SYMBOL(d_alloc_name);
834 EXPORT_SYMBOL(simple_fill_super);
835 EXPORT_SYMBOL(simple_getattr);
836 EXPORT_SYMBOL(simple_link);
837 EXPORT_SYMBOL(simple_lookup);
838 EXPORT_SYMBOL(simple_pin_fs);
839 EXPORT_SYMBOL(simple_prepare_write);
840 EXPORT_SYMBOL(simple_readpage);
841 EXPORT_SYMBOL(simple_release_fs);
842 EXPORT_SYMBOL(simple_rename);
843 EXPORT_SYMBOL(simple_rmdir);
844 EXPORT_SYMBOL(simple_statfs);
845 EXPORT_SYMBOL(simple_sync_file);
846 EXPORT_SYMBOL(simple_unlink);
847 EXPORT_SYMBOL(simple_read_from_buffer);
848 EXPORT_SYMBOL(memory_read_from_buffer);
849 EXPORT_SYMBOL(simple_transaction_get);
850 EXPORT_SYMBOL(simple_transaction_read);
851 EXPORT_SYMBOL(simple_transaction_release);
852 EXPORT_SYMBOL_GPL(simple_attr_open);
853 EXPORT_SYMBOL_GPL(simple_attr_release);
854 EXPORT_SYMBOL_GPL(simple_attr_read);
855 EXPORT_SYMBOL_GPL(simple_attr_write);