On Tue, Mar 10, 2020 at 06:18:00AM +0000, Lin Ma wrote:
> First of all, Thanks for your reply, Stefan.
> 
> We know that the GET LBA STATUS works well under scsi lun passthrough due to the vm directly talks to the scsi target.
> I'm curious that if I use file backend image(say qcow2) + qemu scsi emulation, Does it make sense if I issue sg_get_lba_status in vm to get the lba status?
> If it doesn't make sense, That could explain why qemu scsi emulation layer lack of this support for a long time and no user complains.

It does make sense to implement GET LBA STATUS because QEMU emulates the
UNMAP command.

Be careful though because there is no asynchronous bdrv_block_status()
API yet.  Internally the BlockDriver->bdrv_co_block_status() function is
already asynchronous because it runs in a coroutine.  It will be
necessary to expose a new bdrv_aio_get_block_status() or similar API so
the device models (i.e. SCSI emulation code) can take advantage of that.

Stefan