Orion

/*
 * This file controls the superblock for DevFS.  It supports mounting new DevFS
 * filesystems.  The VFS will use the calls here when dealing directly with the
 * filesystem structure.
 */

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "fs.h"
#include "../vfs.h"
#include "../super.h"
#include "../inode.h"
#include "../../mem/heap.h"

Inode *devfs_mount(FileSystemType *type, int flags,
                   const char *dev, void *data);
Inode *devfs_alloc_inode(SuperBlock *sb);

FileSystemType devfsType = {
	.name    = "DevFS",
	.mount   = devfs_mount,
//	.kill_sb = devfs_kill_sb,
};

SuperOps devfsSuperOps = {
	.alloc_inode  = devfs_alloc_inode,
//	.free_inode   = devfs_free_inode,
//	.write_inode  = devfs_write_inode,
//	.delete_inode = devfs_delete_inode,
};

Inode devfsRoot = {
	.mode = S_IFDIR | 0755,
	.ops = &devfsInodeOps,
	.fileOps = &devfsFileOps,
	.size = 4096,
};

/* Mount a DevFS instance */
Inode *
devfs_mount(FileSystemType *type, int flags, const char *dev, void *data)
{
	if (type != &devfsType)
		return NULL;

	SuperBlock *super = kmalloc(sizeof(SuperBlock));

	super->type = type;
	super->ops = &devfsSuperOps;
	init_lock(&super->lock);

	/*
	 * DevFS is special - it has a globally unique root.  This means that no
	 * matter where a DevFS instance is mounted, it will be mounted with
	 * this inode, meaning the contents are the same.  It basically causes
	 * the mountpoint to act as a hard-link.  This means you can mount a new
	 * DevFS instance in a chroot() environment, and not have to remake all
	 * the device nodes.
	 */
	Inode *inode = &devfsRoot;
	inode->nlink++;
	inode->super = super;
	/* FIXME: need an inode per super, or only one super */
	super->root = inode;
	/* Never free */
	if (!inode->usage)
		inode_get(inode);

	return inode;
}

/* Allocate an inode */
Inode *
devfs_alloc_inode(SuperBlock *sb)
{
	Inode *inode = kmalloc(sizeof(Inode));
	init_lock(&inode->lock);
	inode->ops = &devfsInodeOps;
	inode->fileOps = &devfsFileOps;
	inode->super = sb;
	inode->nlink = 1;
	return inode_get(inode); /* This ensures that the inode is never free */
}