namei.c

elinux jffs初始版本 具体了解JFFS的文件系统！

	*res_inode = inode;
	return 0;
}

int do_mknod(const char * filename, int mode, dev_t dev)
{
	const char * basename;
	int namelen, error;
	struct inode * dir;

	mode &= ~current->fs->umask;
	error = dir_namei(filename, &namelen, &basename, NULL, &dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
		iput(dir);
		return error;
	}
	if (!dir->i_op || !dir->i_op->mknod) {
		iput(dir);
		return -EPERM;
	}
	dir->i_count++;
	if (dir->i_sb && dir->i_sb->dq_op)
		dir->i_sb->dq_op->initialize(dir, -1);
	down(&dir->i_sem);
	error = dir->i_op->mknod(dir,basename,namelen,mode,dev);
	up(&dir->i_sem);
	iput(dir);
	return error;
}

asmlinkage int sys_mknod(const char * filename, int mode, dev_t dev)
{
	int error;
	char * tmp;

	if (S_ISDIR(mode) || (!S_ISFIFO(mode) && !fsuser()))
		return -EPERM;
	switch (mode & S_IFMT) {
	case 0:
		mode |= S_IFREG;
		break;
	case S_IFREG: case S_IFCHR: case S_IFBLK: case S_IFIFO: case S_IFSOCK:
		break;
	default:
		return -EINVAL;
	}
	error = getname(filename,&tmp);
	if (!error) {
		error = do_mknod(tmp,mode,dev);
		putname(tmp);
	}
	return error;
}

/*
 * Some operations need to remove trailing slashes for POSIX.1
 * conformance. For rename we also need to change the behaviour
 * depending on whether we had a trailing slash or not.. (we
 * cannot rename normal files with trailing slashes, only dirs)
 *
 * "dummy" is used to make sure we don't do "/" -> "".
 */
static int remove_trailing_slashes(char * name)
{
	int result;
	char dummy[1];
	char *remove = dummy+1;

	for (;;) {
		char c = *name;
		name++;
		if (!c)
			break;
		if (c != '/') {
			remove = NULL;
			continue;
		}
		if (remove)
			continue;
		remove = name;
	}

	result = 0;
	if (remove) {
		remove[-1] = 0;
		result = 1;
	}

	return result;
}

static int do_mkdir(const char * pathname, int mode)
{
	const char * basename;
	int namelen, error;
	struct inode * dir;

	error = dir_namei(pathname, &namelen, &basename, NULL, &dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
		iput(dir);
		return error;
	}
	if (!dir->i_op || !dir->i_op->mkdir) {
		iput(dir);
		return -EPERM;
	}
	dir->i_count++;
	if (dir->i_sb && dir->i_sb->dq_op)
		dir->i_sb->dq_op->initialize(dir, -1);
	down(&dir->i_sem);
	error = dir->i_op->mkdir(dir, basename, namelen, mode & 01777 & ~current->fs->umask);
	up(&dir->i_sem);
	iput(dir);
	return error;
}

asmlinkage int sys_mkdir(const char * pathname, int mode)
{
	int error;
	char * tmp;

	error = getname(pathname,&tmp);
	if (!error) {
		remove_trailing_slashes(tmp);
		error = do_mkdir(tmp,mode);
		putname(tmp);
	}
	return error;
}

static int do_rmdir(const char * name)
{
	const char * basename;
	int namelen, error;
	struct inode * dir;

	error = dir_namei(name, &namelen, &basename, NULL, &dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
		iput(dir);
		return error;
	}
	/*
	 * A subdirectory cannot be removed from an append-only directory
	 */
	if (IS_APPEND(dir)) {
		iput(dir);
		return -EPERM;
	}
	if (!dir->i_op || !dir->i_op->rmdir) {
		iput(dir);
		return -EPERM;
	}
	if (dir->i_sb && dir->i_sb->dq_op)
		dir->i_sb->dq_op->initialize(dir, -1);
	down(&dir->i_sem);
	error = dir->i_op->rmdir(dir,basename,namelen);
	up(&dir->i_sem);
	return error;
}

asmlinkage int sys_rmdir(const char * pathname)
{
	int error;
	char * tmp;

	error = getname(pathname,&tmp);
	if (!error) {
		remove_trailing_slashes(tmp);
		error = do_rmdir(tmp);
		putname(tmp);
	}
	return error;
}

static int do_unlink(const char * name)
{
	const char * basename;
	int namelen, error;
	struct inode * dir;

	error = dir_namei(name, &namelen, &basename, NULL, &dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -EPERM;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
		iput(dir);
		return error;
	}
	/*
	 * A file cannot be removed from an append-only directory
	 */
	if (IS_APPEND(dir)) {
		iput(dir);
		return -EPERM;
	}
	if (!dir->i_op || !dir->i_op->unlink) {
		iput(dir);
		return -EPERM;
	}
	if (dir->i_sb && dir->i_sb->dq_op)
		dir->i_sb->dq_op->initialize(dir, -1);
	down(&dir->i_sem);
	error = dir->i_op->unlink(dir,basename,namelen);
	up(&dir->i_sem);
	return error;
}

asmlinkage int sys_unlink(const char * pathname)
{
	int error;
	char * tmp;

	error = getname(pathname,&tmp);
	if (!error) {
		error = do_unlink(tmp);
		putname(tmp);
	}
	return error;
}

static int do_symlink(const char * oldname, const char * newname)
{
	struct inode * dir;
	const char * basename;
	int namelen, error;

	error = dir_namei(newname, &namelen, &basename, NULL, &dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
		iput(dir);
		return error;
	}
	if (!dir->i_op || !dir->i_op->symlink) {
		iput(dir);
		return -EPERM;
	}
	dir->i_count++;
	if (dir->i_sb && dir->i_sb->dq_op)
		dir->i_sb->dq_op->initialize(dir, -1);
	down(&dir->i_sem);
	error = dir->i_op->symlink(dir,basename,namelen,oldname);
	up(&dir->i_sem);
	iput(dir);
	return error;
}

asmlinkage int sys_symlink(const char * oldname, const char * newname)
{
	int error;
	char * from, * to;

	error = getname(oldname,&from);
	if (!error) {
		error = getname(newname,&to);
		if (!error) {
			error = do_symlink(from,to);
			putname(to);
		}
		putname(from);
	}
	return error;
}

static int do_link(struct inode * oldinode, const char * newname)
{
	struct inode * dir;
	const char * basename;
	int namelen, error;

	error = dir_namei(newname, &namelen, &basename, NULL, &dir);
	if (error) {
		iput(oldinode);
		return error;
	}
	if (!namelen) {
		iput(oldinode);
		iput(dir);
		return -EPERM;
	}
	if (IS_RDONLY(dir)) {
		iput(oldinode);
		iput(dir);
		return -EROFS;
	}
	if (dir->i_dev != oldinode->i_dev) {
		iput(dir);
		iput(oldinode);
		return -EXDEV;
	}
	if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
		iput(dir);
		iput(oldinode);
		return error;
	}
	/*
	 * A link to an append-only or immutable file cannot be created
	 */
	if (IS_APPEND(oldinode) || IS_IMMUTABLE(oldinode)) {
		iput(dir);
		iput(oldinode);
		return -EPERM;
	}
	if (!dir->i_op || !dir->i_op->link) {
		iput(dir);
		iput(oldinode);
		return -EPERM;
	}
	dir->i_count++;
	if (dir->i_sb && dir->i_sb->dq_op)
		dir->i_sb->dq_op->initialize(dir, -1);
	down(&dir->i_sem);
	error = dir->i_op->link(oldinode, dir, basename, namelen);
	up(&dir->i_sem);
	iput(dir);
	return error;
}

asmlinkage int sys_link(const char * oldname, const char * newname)
{
	int error;
	char * to;
	struct inode * oldinode;

	error = lnamei(oldname, &oldinode);
	if (error)
		return error;
	error = getname(newname,&to);
	if (error) {
		iput(oldinode);
		return error;
	}
	error = do_link(oldinode,to);
	putname(to);
	return error;
}

static int do_rename(const char * oldname, const char * newname, int must_be_dir)
{
	struct inode * old_dir, * new_dir;
	const char * old_base, * new_base;
	int old_len, new_len, error;

	error = dir_namei(oldname, &old_len, &old_base, NULL, &old_dir);
	if (error)
		return error;
	if ((error = permission(old_dir,MAY_WRITE | MAY_EXEC)) != 0) {
		iput(old_dir);
		return error;
	}
	if (!old_len || (old_base[0] == '.' &&
	    (old_len == 1 || (old_base[1] == '.' &&
	     old_len == 2)))) {
		iput(old_dir);
		return -EPERM;
	}
	error = dir_namei(newname, &new_len, &new_base, NULL, &new_dir);
	if (error) {
		iput(old_dir);
		return error;
	}
	if ((error = permission(new_dir,MAY_WRITE | MAY_EXEC)) != 0){
		iput(old_dir);
		iput(new_dir);
		return error;
	}
	if (!new_len || (new_base[0] == '.' &&
	    (new_len == 1 || (new_base[1] == '.' &&
	     new_len == 2)))) {
		iput(old_dir);
		iput(new_dir);
		return -EPERM;
	}
	if (new_dir->i_dev != old_dir->i_dev) {
		iput(old_dir);
		iput(new_dir);
		return -EXDEV;
	}
	if (IS_RDONLY(new_dir) || IS_RDONLY(old_dir)) {
		iput(old_dir);
		iput(new_dir);
		return -EROFS;
	}
	/*
	 * A file cannot be removed from an append-only directory
	 */
	if (IS_APPEND(old_dir)) {
		iput(old_dir);
		iput(new_dir);
		return -EPERM;
	}
	if (!old_dir->i_op || !old_dir->i_op->rename) {
		iput(old_dir);
		iput(new_dir);
		return -EPERM;
	}
	new_dir->i_count++;
	if (new_dir->i_sb && new_dir->i_sb->dq_op)
		new_dir->i_sb->dq_op->initialize(new_dir, -1);
	down(&new_dir->i_sem);
	error = old_dir->i_op->rename(old_dir, old_base, old_len, 
		new_dir, new_base, new_len, must_be_dir);
	up(&new_dir->i_sem);
	iput(new_dir);
	return error;
}

asmlinkage int sys_rename(const char * oldname, const char * newname)
{
	int error;
	char * from, * to;

	error = getname(oldname,&from);
	if (!error) {
		error = getname(newname,&to);
		if (!error) {
			error = do_rename(from,to,
				remove_trailing_slashes(from) |
				remove_trailing_slashes(to));
			putname(to);
		}
		putname(from);
	}
	return error;
}