lvm2/driver/device-mapper/dmfs-table.c

/*
 * dmfs-table.c
 *
 * Copyright (C) 2001 Sistina Software
 *
 * This software is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2, or (at
 * your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <linux/config.h>
#include <linux/fs.h>

static int dmfs_release(struct inode *inode, struct file *f)
{
	struct dm_table *table;

       /* FIXME: we should lock the inode to
           prevent someone else opening it while
           we are parsing */

	if (!(f->f_mode & S_IWUGO))
		return 0;

}

static int dmfs_readpage(struct file *file, struct page *page)
{
	if (!PageUptodate(page)) {
		memset(kmap(page), 0, PAGE_CACHE_SIZE);
		kunmap(page);
		flush_dcache_page(page);
		SetPageUptodate(page);
	}
	UnlockPage(page);
	return 0;
}

static int dmfs_writepage(struct page *page)
{
	SetPageDirty(page);
	UnlockPage(page);
	return 0;
}

static int dmfs_prepare_write(struct file *file, struct page *page,
			      unsigned offset, unsigned to)
{
	void *addr = kmap(page);
	if (!Page_Uptodate(page)) {
		memset(addr, 0, PAGE_CACHE_SIZE);
		flush_dcache_page(page);
		SetPageUptodate(page);
	}
	SetPageDirty(page);
	return 0;
}

static int dmfs_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;

	kunmap(page);
	if (pos > inode->i_size)
		inode->i_size = pos;
	return 0;
}

static int dmfs_table_sync(struct file *file, struct dentry *dentry, int datasync)
{
	return 0;
}

static struct dm_table_address_space_operations = {
	readpage:	dmfs_readpage,
	writepage:	dmfs_writepage,
	prepare_write:	dmfs_prepare_write,
	commit_write:	dmfs_commit_write,
};

static struct dm_table_file_operations = {
 	llseek:		generic_file_llseek,
	read:		generic_file_read,
	write:		generic_file_write,
	mmap:		generic_file_mmap,
	fsync:		dmfs_table_sync,
	release:	dmfs_release,
};

static struct dmfs_table_inode_operations = {
};

int dmfs_create_table(struct inode *dir, int mode)
{
	struct inode *inode = new_inode(dir->i_sb);

	if (inode) {
		inode->i_mode = mode | S_IFREG;
		inode->i_uid = current->fsuid;
		inode->i_gid = current->fsgid;
		inode->i_blksize = PAGE_CACHE_SIZE;
		inode->i_blocks = 0;
		inode->i_rdev = NODEV;
		inode->i_atime = inode->i_ctime = inode->i_mtime = CURRENT_TIME;
		inode->i_mapping->a_ops = &dmfs_table_address_space_operations;
		inode->i_fop = &dmfs_table_file_operations;
		inode->i_op = &dmfs_table_inode_operations;
	}

	return inode;
}