static int loop_configure()

in loop.c [945:1083]

• 108 lines of code
• 25 McCabe index (conditional complexity)

static int loop_configure(struct loop_device *lo, fmode_t mode,
			  struct block_device *bdev,
			  const struct loop_config *config)
{
	struct file *file = fget(config->fd);
	struct inode *inode;
	struct address_space *mapping;
	int error;
	loff_t size;
	bool partscan;
	unsigned short bsize;
	bool is_loop;

	if (!file)
		return -EBADF;
	is_loop = is_loop_device(file);

	/* This is safe, since we have a reference from open(). */
	__module_get(THIS_MODULE);

	/*
	 * If we don't hold exclusive handle for the device, upgrade to it
	 * here to avoid changing device under exclusive owner.
	 */
	if (!(mode & FMODE_EXCL)) {
		error = bd_prepare_to_claim(bdev, loop_configure);
		if (error)
			goto out_putf;
	}

	error = loop_global_lock_killable(lo, is_loop);
	if (error)
		goto out_bdev;

	error = -EBUSY;
	if (lo->lo_state != Lo_unbound)
		goto out_unlock;

	error = loop_validate_file(file, bdev);
	if (error)
		goto out_unlock;

	mapping = file->f_mapping;
	inode = mapping->host;

	if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
		error = -EINVAL;
		goto out_unlock;
	}

	if (config->block_size) {
		error = blk_validate_block_size(config->block_size);
		if (error)
			goto out_unlock;
	}

	error = loop_set_status_from_info(lo, &config->info);
	if (error)
		goto out_unlock;

	if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
	    !file->f_op->write_iter)
		lo->lo_flags |= LO_FLAGS_READ_ONLY;

	lo->workqueue = alloc_workqueue("loop%d",
					WQ_UNBOUND | WQ_FREEZABLE,
					0,
					lo->lo_number);
	if (!lo->workqueue) {
		error = -ENOMEM;
		goto out_unlock;
	}

	disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
	set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);

	INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
	INIT_LIST_HEAD(&lo->rootcg_cmd_list);
	INIT_LIST_HEAD(&lo->idle_worker_list);
	lo->worker_tree = RB_ROOT;
	timer_setup(&lo->timer, loop_free_idle_workers,
		TIMER_DEFERRABLE);
	lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
	lo->lo_device = bdev;
	lo->lo_backing_file = file;
	lo->old_gfp_mask = mapping_gfp_mask(mapping);
	mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));

	if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
		blk_queue_write_cache(lo->lo_queue, true, false);

	if (config->block_size)
		bsize = config->block_size;
	else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev)
		/* In case of direct I/O, match underlying block size */
		bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
	else
		bsize = 512;

	blk_queue_logical_block_size(lo->lo_queue, bsize);
	blk_queue_physical_block_size(lo->lo_queue, bsize);
	blk_queue_io_min(lo->lo_queue, bsize);

	loop_config_discard(lo);
	loop_update_rotational(lo);
	loop_update_dio(lo);
	loop_sysfs_init(lo);

	size = get_loop_size(lo, file);
	loop_set_size(lo, size);

	/* Order wrt reading lo_state in loop_validate_file(). */
	wmb();

	lo->lo_state = Lo_bound;
	if (part_shift)
		lo->lo_flags |= LO_FLAGS_PARTSCAN;
	partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
	if (partscan)
		lo->lo_disk->flags &= ~GENHD_FL_NO_PART;

	loop_global_unlock(lo, is_loop);
	if (partscan)
		loop_reread_partitions(lo);
	if (!(mode & FMODE_EXCL))
		bd_abort_claiming(bdev, loop_configure);
	return 0;

out_unlock:
	loop_global_unlock(lo, is_loop);
out_bdev:
	if (!(mode & FMODE_EXCL))
		bd_abort_claiming(bdev, loop_configure);
out_putf:
	fput(file);
	/* This is safe: open() is still holding a reference. */
	module_put(THIS_MODULE);
	return error;
}