> +config BLKSNAP_DIFF_BLKDEV > + bool "Use an optimized algorithm to store difference on a block device" > + depends on BLKSNAP > + default y > + help > + The difference storage for a snapshot can be a regular file or a > + block device. We can work with a block device through the interface > + of a regular file. However, direct management of I/O units should > + allow for higher performance. Is there much of a point in making this option? Btw, Linus hates defaul y, so we should not have one in there. > +config BLKSNAP_CHUNK_DIFF_BIO_SYNC > + bool "Use a synchronous I/O unit processing algorithm for the snapshot image" > + depends on BLKSNAP > + default n n the default default, so no need to add it. But unless there is a really good reason to have two different bio submission mechanisms upstream I'd strongly suggest dropping one of them and this option.