Linux generic storage model

Today SATA subsystem (libATA) and USB block driver (usb-storage) are using SCSI stack because it provides a convenient way for adding hardware support without the need for duplicating a lot of code (managing devices, command queueing, error handling etc). At hardware layer these devices support some SCSI commands (i.e. MMC command set on ATAPI devices) while some other commands are emulated in order to interoperate with SCSI subsystem and allow unmodified device drivers (sd, sr, st and sg) to work. The main motivation for introducing generic storage model is removing dependency on SCSI stack for SATA/USB block devices while at the same time making Linux storage system more flexible and allowing easier integration of support for future hardware (full Serial Attached SCSI support).  The purpose of BoFS will be to present the current state of affairs and discuss the ideas in the larger community.