target: Pass through I/O topology for block backstores
In addition to block size (already implemented), passing through
alignment offset, logical-to-phys block exponent, I/O granularity and
optimal I/O length will allow initiators to properly handle layout on
LUNs with 4K block sizes.
Tested with various weird values via scsi_debug module.
One thing to look at with this patch is the new block limits values --
instead of granularity 1 optimal 8192, Lio will now be returning whatever
the block device says, which may affect performance.
Signed-off-by: Andy Grover <agrover@redhat.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 5ebe21c..39e0114 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -34,6 +34,11 @@
sense_reason_t (*parse_cdb)(struct se_cmd *cmd);
u32 (*get_device_type)(struct se_device *);
sector_t (*get_blocks)(struct se_device *);
+ sector_t (*get_alignment_offset_lbas)(struct se_device *);
+ /* lbppbe = logical blocks per physical block exponent. see SBC-3 */
+ unsigned int (*get_lbppbe)(struct se_device *);
+ unsigned int (*get_io_min)(struct se_device *);
+ unsigned int (*get_io_opt)(struct se_device *);
unsigned char *(*get_sense_buffer)(struct se_cmd *);
bool (*get_write_cache)(struct se_device *);
};