[illumos-Developer] Review --> iSCSI UNMAP support

[Deano]

iSCSI is a device level block protocol, just like the original SCSI protocol
it basic job is to say "I have N blocks, and you can read and write them".
How those blocks are managed, reserved, divided up etc. is the job of the
file system on top.

UNMAP is just the protocol to update an in-use state per block, nothing
else, it shouldn't imply any ownership semantics.

Reservation of blocks is something for a higher layers than SCSI or SATA.
There is a use (and the reason for UNMAP / TRIM) to say whether a block has
useful data or not.

My 2p,
Deano
deano at cloudpixies.com