tcm: TPE/TPU -> Block Discard emulation updates for v4.0.0-rc5

From: Nicholas Bellinger <[email protected]>

Greetings all,

This series adds some follow up TPE/TPU emulation patches for TCM Core and IBLOCK + FILEIO -> Block Discard emulation.

The first renames the current DEV_ATTRIB(dev)->emulate_tpe configfs attr to an explict signaling of UNMAP emulation support with DEV_ATTRIB(dev)->emulate_tpu. This was done because the meaning of TPE=1 will be changing in future SBC3 specs, and we need to support both TPU and TPWS for TCM/IBLOCK and TCM/FILEIO subsystem plugins.

The second adds support for INQUIRY EVPD Thin Provisioning VPD (0xb2) emulation for IBLOCK + FILEIO backstores w/ blk_queue_discard()=1 following mkp's recommendation.

The third adds support for filling in the proper max_unmap_lba_count, max_unmap_block_desc_count, unmap_granularity, and unmap_granularity_alignment from generic struct request_queue->limits values reported by the underlying SCSI (TPU/TPWS) and SATA (TRIM) HW accordingly.

So far these patches have been tested with TCM_Loop -> TCM/IBLOCK -> scsi_debug backstores, and sg_vpd output has been included in the second and third patches for reference.

Many, many thanks to Martin Petersen for answering questions wrt to TPE/TPU/TPWS -> Block Discard translation and EVPD 0xb2 THRESHOLD EXPONENT usage!

Thanks mkp!

Nicholas Bellinger (3):
tcm: Rename device attribute emulate_tpe to emulate_tpu
tcm: Add Thin Provisioning VPD page emulation tcm/iblock,fileio: Fill in remaining Block Limits VPD from rq->limits

 drivers/target/target_core_configfs.c  |    6 ++--
 drivers/target/target_core_device.c    |    8 +++---
 drivers/target/target_core_file.c      |   18 +++++++++++-
 drivers/target/target_core_iblock.c    |   19 +++++++++++--
 drivers/target/target_core_transport.c |   44 +++++++++++++++++++++++++++----
 include/target/target_core_base.h      |    2 +-
 include/target/target_core_device.h    |    2 +-
 include/target/target_core_transport.h |    4 +-
 8 files changed, 81 insertions(+), 22 deletions(-)