Re: [PATCH -next v2 1/9] blk-iocost: cleanup ioc_qos_write() and ioc_cost_model_write()

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

> +	ret = nbytes;

ret is an int which bytes is a size_t.  So we at least need a ssize_t
instead for ret, and even that assumes nbytes never overflows a ssize_t.