Currently iblock always reports MAXIMUM TRANSFER LENGTH in 512b units
regardless of the LU block size.
Target block size:
target:~ # fdisk -l /dev/nullb0
Disk /dev/nullb0: 250 GiB, 268435456000 bytes, 65536000 sectors
Units: sectors of 1 * 4096 = 4096 bytes
Sector size (logical/physical): 4096 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Initiator block size:
initiator:~ # fdisk -l /dev/sdc
Disk /dev/sdc: 250 GiB, 268435456000 bytes, 65536000 sectors
Disk model: nullb0
Units: sectors of 1 * 4096 = 4096 bytes
Sector size (logical/physical): 4096 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 131072 bytes
target max transfer length limit:
target:~ # cat /sys/block/nullb0/queue/max_hw_sectors_kb
128
So the maximum transfer length should be 128 * 1024 / 4096 = 32 blocks
But the target sends MTL in 512b units, so the initiators see 256 blocks
instead.
initiator:~ # sg_inq -p 0xb0 /dev/sdc
VPD INQUIRY: Block limits page (SBC)
Maximum compare and write length: 1 blocks
Optimal transfer length granularity: 1 blocks
Maximum transfer length: 256 blocks
Optimal transfer length: 32 blocks
Maximum prefetch transfer length: 0 blocks [ignored]
This happens because MAXIMUM TRANSFER LENGTH field in VPD Block Limits
page is derived from dev->dev_attrib.hw_max_sectors which happens to be
in 512b units for iblock. This patch series fixes this issue and removes
some special-casing for other backstores.
Anastasia Kovaleva (3):
target: core: Send mtl in blocks
target: core: make hw_max_sectors store the sectors amount in blocks
target: core: Change the way target_xcopy_do_work sets restiction on
max io
drivers/target/target_core_configfs.c | 2 -
drivers/target/target_core_file.c | 1 -
drivers/target/target_core_iblock.c | 3 +-
drivers/target/target_core_spc.c | 7 ++-
drivers/target/target_core_xcopy.c | 68 ++++++++++++++-------------
drivers/target/target_core_xcopy.h | 2 +-
include/target/target_core_base.h | 1 -
7 files changed, 45 insertions(+), 39 deletions(-)
--
2.30.2
