btrfs_mkdir

static struct super_operations btrfs_super_ops;

static struct file_operations btrfs_dir_file_operations;

#if 0

/* some random number */

static struct super_operations ramfs_ops;

static struct backing_dev_info ramfs_backing_dev_info = {

	.ra_pages	= 0,	/* No readahead */

	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK |

			  BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |

			  BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,

};

struct inode *ramfs_get_inode(struct super_block *sb, int mode, dev_t dev)

{

	struct inode * inode = new_inode(sb);

	if (inode) {

		inode->i_mode = mode;

		inode->i_uid = current->fsuid;

		inode->i_gid = current->fsgid;

		inode->i_blocks = 0;

		inode->i_mapping->a_ops = &ramfs_aops;

		inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;

		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;

		switch (mode & S_IFMT) {

		default:

			init_special_inode(inode, mode, dev);

			break;

		case S_IFREG:

			inode->i_op = &ramfs_file_inode_operations;

			inode->i_fop = &ramfs_file_operations;

			break;

		case S_IFDIR:

			inode->i_op = &ramfs_dir_inode_operations;

			inode->i_fop = &simple_dir_operations;

			/* directory inodes start off with i_nlink == 2 (for "." entry) */

			inc_nlink(inode);

			break;

		case S_IFLNK:

			inode->i_op = &page_symlink_inode_operations;

			break;

		}

	}

	return inode;

}

/*

 * File creation. Allocate an inode, and we're done..

 */

/* SMP-safe */

static int

ramfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)

{

	struct inode * inode = ramfs_get_inode(dir->i_sb, mode, dev);

	int error = -ENOSPC;

	if (inode) {

		if (dir->i_mode & S_ISGID) {

			inode->i_gid = dir->i_gid;

			if (S_ISDIR(mode))

				inode->i_mode |= S_ISGID;

		}

		d_instantiate(dentry, inode);

		dget(dentry);	/* Extra count - pin the dentry in core */

		error = 0;

		dir->i_mtime = dir->i_ctime = CURRENT_TIME;

	}

	return error;

}

static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)

{

	int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);

	if (!retval)

		inc_nlink(dir);

	return retval;

}

static int ramfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)

{

	return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);

}

static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)

{

	struct inode *inode;

	int error = -ENOSPC;

	inode = ramfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);

	if (inode) {

		int l = strlen(symname)+1;

		error = page_symlink(inode, symname, l);

		if (!error) {

			if (dir->i_mode & S_ISGID)

				inode->i_gid = dir->i_gid;

			d_instantiate(dentry, inode);

			dget(dentry);

			dir->i_mtime = dir->i_ctime = CURRENT_TIME;

		} else

			iput(inode);

	}

	return error;

}

static struct inode_operations ramfs_dir_inode_operations = {

	.create		= ramfs_create,

	.lookup		= simple_lookup,

	.link		= simple_link,

	.unlink		= simple_unlink,

	.symlink	= ramfs_symlink,

	.mkdir		= ramfs_mkdir,

	.rmdir		= simple_rmdir,

	.mknod		= ramfs_mknod,

	.rename		= simple_rename,

};

#endif

static void btrfs_read_locked_inode(struct inode *inode)

{

	struct btrfs_path path;

	inode->i_ino = objectid;

	inode->i_blocks = 0;

	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;

	/* FIXME do this on link */

	if (mode & S_IFDIR)

		inode->i_size = 3;

	fill_inode_item(&inode_item, inode);

	key.objectid = objectid;

	key.flags = 0;

	key.offset = 0;

	return err;

}

static int btrfs_make_empty_dir(struct btrfs_trans_handle *trans,

				struct inode *inode, struct inode *dir)

{

	struct btrfs_root *root = btrfs_sb(inode->i_sb);

	int ret;

	char buf[2];

	buf[0] = '.';

	buf[1] = '.';

	ret = btrfs_insert_dir_item(trans, root, buf, 1, inode->i_ino,

				    inode->i_ino, 1);

	if (ret)

		goto error;

	ret = btrfs_insert_dir_item(trans, root, buf, 2, inode->i_ino,

				    dir->i_ino, 1);

error:

	return ret;

}

static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)

{

	struct inode *inode;

	struct btrfs_trans_handle *trans;

	struct btrfs_root *root = btrfs_sb(dir->i_sb);

	int err = 0;

	int drop_on_err = 0;

	mutex_lock(&root->fs_info->fs_mutex);

	trans = btrfs_start_transaction(root, 1);

	if (IS_ERR(trans)) {

		err = PTR_ERR(trans);

		goto out_unlock;

	}

	inode = btrfs_new_inode(trans, dir, S_IFDIR | mode);

	if (IS_ERR(inode)) {

		err = PTR_ERR(inode);

		goto out_fail;

	}

	drop_on_err = 1;

	inode->i_op = &btrfs_dir_inode_operations;

	inode->i_fop = &btrfs_dir_file_operations;

	err = btrfs_make_empty_dir(trans, inode, dir);

	if (err)

		goto out_fail;

	err = btrfs_add_link(trans, dentry, inode);

	if (err)

		goto out_fail;

	d_instantiate(dentry, inode);

	mark_inode_dirty(inode);

	drop_on_err = 0;

out_fail:

	btrfs_end_transaction(trans, root);

out_unlock:

	mutex_unlock(&root->fs_info->fs_mutex);

	if (drop_on_err)

		iput(inode);

	return err;

}

static int btrfs_sync_fs(struct super_block *sb, int wait)

{

	struct btrfs_trans_handle *trans;

	.lookup		= btrfs_lookup,

	.create		= btrfs_create,

	.unlink		= btrfs_unlink,

	.mkdir		= btrfs_mkdir,

};

static struct file_operations btrfs_dir_file_operations = {