static int open_ubd_file()

in drivers/ubd_kern.c [625:702]

• 68 lines of code
• 18 McCabe index (conditional complexity)

static int open_ubd_file(char *file, struct openflags *openflags, int shared,
		  char **backing_file_out, int *bitmap_offset_out,
		  unsigned long *bitmap_len_out, int *data_offset_out,
		  int *create_cow_out)
{
	time64_t mtime;
	unsigned long long size;
	__u32 version, align;
	char *backing_file;
	int fd, err, sectorsize, asked_switch, mode = 0644;

	fd = os_open_file(file, *openflags, mode);
	if (fd < 0) {
		if ((fd == -ENOENT) && (create_cow_out != NULL))
			*create_cow_out = 1;
		if (!openflags->w ||
		    ((fd != -EROFS) && (fd != -EACCES)))
			return fd;
		openflags->w = 0;
		fd = os_open_file(file, *openflags, mode);
		if (fd < 0)
			return fd;
	}

	if (shared)
		printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
	else {
		err = os_lock_file(fd, openflags->w);
		if (err < 0) {
			printk(KERN_ERR "Failed to lock '%s', err = %d\n",
			       file, -err);
			goto out_close;
		}
	}

	/* Successful return case! */
	if (backing_file_out == NULL)
		return fd;

	err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
			      &size, &sectorsize, &align, bitmap_offset_out);
	if (err && (*backing_file_out != NULL)) {
		printk(KERN_ERR "Failed to read COW header from COW file "
		       "\"%s\", errno = %d\n", file, -err);
		goto out_close;
	}
	if (err)
		return fd;

	asked_switch = path_requires_switch(*backing_file_out, backing_file,
					    file);

	/* Allow switching only if no mismatch. */
	if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
						   mtime)) {
		printk(KERN_ERR "Switching backing file to '%s'\n",
		       *backing_file_out);
		err = write_cow_header(file, fd, *backing_file_out,
				       sectorsize, align, &size);
		if (err) {
			printk(KERN_ERR "Switch failed, errno = %d\n", -err);
			goto out_close;
		}
	} else {
		*backing_file_out = backing_file;
		err = backing_file_mismatch(*backing_file_out, size, mtime);
		if (err)
			goto out_close;
	}

	cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
		  bitmap_len_out, data_offset_out);

	return fd;
 out_close:
	os_close_file(fd);
	return err;
}