[$] Accessing zoned block devices with zonefs

Zoned block devices are quite different than the block devices most peopleare used to. The concept came from shingledmagnetic recording (SMR) devices, which allow much higher densitystorage, but that extra capacity comes with a price: less flexibility. Zoneddevices have regions (zones) that can only be written sequentially; thereis no random access for writes to those zones. Linux already supports thesedevices, and filesystems are adding support as well, but some applicationsmay want a simpler, more straightforward interface; that's what a newfilesystem, zonefs, is targeting.