/* *	fs/libfs.c *	Library for filesystems writers. */ #include <linux/module.h>#include <linux/pagemap.h>#include <linux/mount.h>#include <linux/vfs.h>#include <linux/mutex.h> #include <asm/uaccess.h> int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,		   struct kstat *stat){	struct inode *inode = dentry->d_inode;	generic_fillattr(inode, stat);	stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);	return 0;} int simple_statfs(struct super_block *sb, struct kstatfs *buf){	buf->f_type = sb->s_magic;	buf->f_bsize = PAGE_CACHE_SIZE;	buf->f_namelen = NAME_MAX;	return 0;} /* * Retaining negative dentries for an in-memory filesystem just wastes * memory and lookup time: arrange for them to be deleted immediately. */static int simple_delete_dentry(struct dentry *dentry){	return 1;} /* * Lookup the data. This is trivial - if the dentry didn't already * exist, we know it is negative.  Set d_op to delete negative dentries. */struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){	static struct dentry_operations simple_dentry_operations = {		.d_delete = simple_delete_dentry,	}; 	if (dentry->d_name.len > NAME_MAX)		return ERR_PTR(-ENAMETOOLONG);	dentry->d_op = &simple_dentry_operations;	d_add(dentry, NULL);	return NULL;} int simple_sync_file(struct file * file, struct dentry *dentry, int datasync){	return 0;} int dcache_dir_open(struct inode *inode, struct file *file){	static struct qstr cursor_name = {.len = 1, .name = "."}; 	file->private_data = d_alloc(file->f_dentry, &cursor_name); 	return file->private_data ? 0 : -ENOMEM;} int dcache_dir_close(struct inode *inode, struct file *file){	dput(file->private_data);	return 0;} loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin){	mutex_lock(&file->f_dentry->d_inode->i_mutex);	switch (origin) {		case 1:			offset += file->f_pos;		case 0:			if (offset >= 0)				break;		default:			mutex_unlock(&file->f_dentry->d_inode->i_mutex);			return -EINVAL;	}	if (offset != file->f_pos) {		file->f_pos = offset;		if (file->f_pos >= 2) {			struct list_head *p;			struct dentry *cursor = file->private_data;			loff_t n = file->f_pos - 2; 			spin_lock(&dcache_lock);			list_del(&cursor->d_u.d_child);			p = file->f_dentry->d_subdirs.next;			while (n && p != &file->f_dentry->d_subdirs) {				struct dentry *next;				next = list_entry(p, struct dentry, d_u.d_child);				if (!d_unhashed(next) && next->d_inode)					n--;				p = p->next;			}			list_add_tail(&cursor->d_u.d_child, p);			spin_unlock(&dcache_lock);		}	}	mutex_unlock(&file->f_dentry->d_inode->i_mutex);	return offset;} /* Relationship between i_mode and the DT_xxx types */static inline unsigned char dt_type(struct inode *inode){	return (inode->i_mode >> 12) & 15;} /* * Directory is locked and all positive dentries in it are safe, since * for ramfs-type trees they can't go away without unlink() or rmdir(), * both impossible due to the lock on directory. */ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir){	struct dentry *dentry = filp->f_dentry;	struct dentry *cursor = filp->private_data;	struct list_head *p, *q = &cursor->d_u.d_child;	ino_t ino;	int i = filp->f_pos; 	switch (i) {		case 0:			ino = dentry->d_inode->i_ino;			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)				break;			filp->f_pos++;			i++;			/* fallthrough */		case 1:			ino = parent_ino(dentry);			if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)				break;			filp->f_pos++;			i++;			/* fallthrough */		default:			spin_lock(&dcache_lock);			if (filp->f_pos == 2) {				list_del(q);				list_add(q, &dentry->d_subdirs);			}			for (p=q->next; p != &dentry->d_subdirs; p=p->next) {				struct dentry *next;				next = list_entry(p, struct dentry, d_u.d_child);				if (d_unhashed(next) || !next->d_inode)					continue; 				spin_unlock(&dcache_lock);				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)					return 0;				spin_lock(&dcache_lock);				/* next is still alive */				list_del(q);				list_add(q, p);				p = q;				filp->f_pos++;			}			spin_unlock(&dcache_lock);	}	return 0;} ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos){	return -EISDIR;} const struct file_operations simple_dir_operations = {	.open		= dcache_dir_open,	.release	= dcache_dir_close,	.llseek		= dcache_dir_lseek,	.read		= generic_read_dir,	.readdir	= dcache_readdir,	.fsync		= simple_sync_file,}; struct inode_operations simple_dir_inode_operations = {	.lookup		= simple_lookup,}; /* * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that * will never be mountable) */struct super_block *get_sb_pseudo(struct file_system_type *fs_type, char *name,	struct super_operations *ops, unsigned long magic){	struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);	static struct super_operations default_ops = {.statfs = simple_statfs};	struct dentry *dentry;	struct inode *root;	struct qstr d_name = {.name = name, .len = strlen(name)}; 	if (IS_ERR(s))		return s; 	s->s_flags = MS_NOUSER;	s->s_maxbytes = ~0ULL;	s->s_blocksize = 1024;	s->s_blocksize_bits = 10;	s->s_magic = magic;	s->s_op = ops ? ops : &default_ops;	s->s_time_gran = 1;	root = new_inode(s);	if (!root)		goto Enomem;	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;	root->i_uid = root->i_gid = 0;	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;	dentry = d_alloc(NULL, &d_name);	if (!dentry) {		iput(root);		goto Enomem;	}	dentry->d_sb = s;	dentry->d_parent = dentry;	d_instantiate(dentry, root);	s->s_root = dentry;	s->s_flags |= MS_ACTIVE;	return s; Enomem:	up_write(&s->s_umount);	deactivate_super(s);	return ERR_PTR(-ENOMEM);} int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry){	struct inode *inode = old_dentry->d_inode; 	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;	inode->i_nlink++;	atomic_inc(&inode->i_count);	dget(dentry);	d_instantiate(dentry, inode);	return 0;} static inline int simple_positive(struct dentry *dentry){	return dentry->d_inode && !d_unhashed(dentry);} int simple_empty(struct dentry *dentry){	struct dentry *child;	int ret = 0; 	spin_lock(&dcache_lock);	list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)		if (simple_positive(child))			goto out;	ret = 1;out:	spin_unlock(&dcache_lock);	return ret;} int simple_unlink(struct inode *dir, struct dentry *dentry){	struct inode *inode = dentry->d_inode; 	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;	inode->i_nlink--;	dput(dentry);	return 0;} int simple_rmdir(struct inode *dir, struct dentry *dentry){	if (!simple_empty(dentry))		return -ENOTEMPTY; 	dentry->d_inode->i_nlink--;	simple_unlink(dir, dentry);	dir->i_nlink--;	return 0;} int simple_rename(struct inode *old_dir, struct dentry *old_dentry,		struct inode *new_dir, struct dentry *new_dentry){	struct inode *inode = old_dentry->d_inode;	int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); 	if (!simple_empty(new_dentry))		return -ENOTEMPTY; 	if (new_dentry->d_inode) {		simple_unlink(new_dir, new_dentry);		if (they_are_dirs)			old_dir->i_nlink--;	} else if (they_are_dirs) {		old_dir->i_nlink--;		new_dir->i_nlink++;	} 	old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =		new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; 	return 0;} int simple_readpage(struct file *file, struct page *page){	void *kaddr; 	if (PageUptodate(page))		goto out; 	kaddr = kmap_atomic(page, KM_USER0);	memset(kaddr, 0, PAGE_CACHE_SIZE);	kunmap_atomic(kaddr, KM_USER0);	flush_dcache_page(page);	SetPageUptodate(page);out:	unlock_page(page);	return 0;} int simple_prepare_write(struct file *file, struct page *page,			unsigned from, unsigned to){	if (!PageUptodate(page)) {		if (to - from != PAGE_CACHE_SIZE) {			void *kaddr = kmap_atomic(page, KM_USER0);			memset(kaddr, 0, from);			memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);			flush_dcache_page(page);			kunmap_atomic(kaddr, KM_USER0);		}		SetPageUptodate(page);	}	return 0;} int simple_commit_write(struct file *file, struct page *page,			unsigned offset, unsigned to){	struct inode *inode = page->mapping->host;	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; 	/*	 * No need to use i_size_read() here, the i_size	 * cannot change under us because we hold the i_mutex.	 */	if (pos > inode->i_size)		i_size_write(inode, pos);	set_page_dirty(page);	return 0;} int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files){	static struct super_operations s_ops = {.statfs = simple_statfs};	struct inode *inode;	struct dentry *root;	struct dentry *dentry;	int i; 	s->s_blocksize = PAGE_CACHE_SIZE;	s->s_blocksize_bits = PAGE_CACHE_SHIFT;	s->s_magic = magic;	s->s_op = &s_ops;	s->s_time_gran = 1; 	inode = new_inode(s);	if (!inode)		return -ENOMEM;	inode->i_mode = S_IFDIR | 0755;	inode->i_uid = inode->i_gid = 0;	inode->i_blksize = PAGE_CACHE_SIZE;	inode->i_blocks = 0;	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;	inode->i_op = &simple_dir_inode_operations;	inode->i_fop = &simple_dir_operations;	inode->i_nlink = 2;	root = d_alloc_root(inode);	if (!root) {		iput(inode);		return -ENOMEM;	}	for (i = 0; !files->name || files->name[0]; i++, files++) {		if (!files->name)			continue;		dentry = d_alloc_name(root, files->name);		if (!dentry)			goto out;		inode = new_inode(s);		if (!inode)			goto out;		inode->i_mode = S_IFREG | files->mode;		inode->i_uid = inode->i_gid = 0;		inode->i_blksize = PAGE_CACHE_SIZE;		inode->i_blocks = 0;		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;		inode->i_fop = files->ops;		inode->i_ino = i;		d_add(dentry, inode);	}	s->s_root = root;	return 0;out:	d_genocide(root);	dput(root);	return -ENOMEM;} static DEFINE_SPINLOCK(pin_fs_lock); int simple_pin_fs(char *name, struct vfsmount **mount, int *count){	struct vfsmount *mnt = NULL;	spin_lock(&pin_fs_lock);	if (unlikely(!*mount)) {		spin_unlock(&pin_fs_lock);		mnt = do_kern_mount(name, 0, name, NULL);		if (IS_ERR(mnt))			return PTR_ERR(mnt);		spin_lock(&pin_fs_lock);		if (!*mount)			*mount = mnt;	}	mntget(*mount);	++*count;	spin_unlock(&pin_fs_lock);	mntput(mnt);	return 0;} void simple_release_fs(struct vfsmount **mount, int *count){	struct vfsmount *mnt;	spin_lock(&pin_fs_lock);	mnt = *mount;	if (!--*count)		*mount = NULL;	spin_unlock(&pin_fs_lock);	mntput(mnt);} ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,				const void *from, size_t available){	loff_t pos = *ppos;	if (pos < 0)		return -EINVAL;	if (pos >= available)		return 0;	if (count > available - pos)		count = available - pos;	if (copy_to_user(to, from + pos, count))		return -EFAULT;	*ppos = pos + count;	return count;} /* * Transaction based IO. * The file expects a single write which triggers the transaction, and then * possibly a read which collects the result - which is stored in a * file-local buffer. */char *simple_transaction_get(struct file *file, const char __user *buf, size_t size){	struct simple_transaction_argresp *ar;	static DEFINE_SPINLOCK(simple_transaction_lock); 	if (size > SIMPLE_TRANSACTION_LIMIT - 1)		return ERR_PTR(-EFBIG); 	ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);	if (!ar)		return ERR_PTR(-ENOMEM); 	spin_lock(&simple_transaction_lock); 	/* only one write allowed per open */	if (file->private_data) {		spin_unlock(&simple_transaction_lock);		free_page((unsigned long)ar);		return ERR_PTR(-EBUSY);	} 

Lines 1–500 of 653. Load more