Re: [PATCH v2 13/21] block, blksnap: functions and structures for performing block I/O operations

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

> +	bio = bio_alloc_bioset(diff_region->bdev, nr_iovecs, opf, gfp_mask,
> +			       &diff_io_bioset);
> +	if (unlikely(!bio)) {
> +		if (is_nowait)
> +			ret = -EAGAIN;
> +		else
> +			ret = -ENOMEM;
> +		goto fail;

bio_alloc_bioset can't fail for the !is_nowait case.