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>
This commit is contained in:
Andy Grover 2013-11-11 08:59:17 -08:00 committed by Nicholas Bellinger
parent f01b9f7339
commit 7f7caf6aa7
4 changed files with 68 additions and 3 deletions

View file

@ -34,6 +34,11 @@ struct se_subsystem_api {
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 *);
};