[PATCH 4/5] lio: use REQ_COMPARE_AND_WRITE if supported

michaelc
2014-10-16T05:37:14Z

From: Mike Christie <michaelc@cs.wisc.edu>

This has lio callout to the backing store module if it supports
using REQ_COMPARE_AND_WRITE. The backing store would set the
device attribute max_compare_and_write_len if it supports using
the new request type. If it is not supported then we do the
read/cmp/write emulation in the sbc layer like before.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
---
drivers/target/target_core_sbc.c | 21 ++++++++++++++++-----
drivers/target/target_core_spc.c | 12 ++++++++++--
drivers/target/target_core_transport.c | 1 +
include/target/target_core_backend.h | 1 +
include/target/target_core_base.h | 1 +
5 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index ebe62af..fe0c16a 100644
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -555,6 +555,21 @@ sbc_compare_and_write(struct se_cmd *cmd)
return TCM_NO_SENSE;
}

+static void sbc_setup_compare_and_write(struct se_cmd *cmd, struct sbc_ops *ops,
+ u32 sectors)
+{
+ cmd->t_task_nolb = sectors;
+ cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB | SCF_COMPARE_AND_WRITE;
+
+ if (cmd->se_dev->dev_attrib.max_compare_and_write_len) {
+ cmd->execute_cmd = ops->execute_compare_and_write;
+ } else {
+ cmd->execute_rw = ops->execute_rw;
+ cmd->execute_cmd = sbc_compare_and_write;
+ cmd->transport_complete_callback = compare_and_write_callback;
+ }
+}
+
static int
sbc_set_prot_op_checks(u8 protect, enum target_prot_type prot_type,
bool is_write, struct se_cmd *cmd)
@@ -842,11 +857,7 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
*/
size = 2 * sbc_get_size(cmd, sectors);
cmd->t_task_lba = get_unaligned_be64(&cdb[2]);
- cmd->t_task_nolb = sectors;
- cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB | SCF_COMPARE_AND_WRITE;
- cmd->execute_rw = ops->execute_rw;
- cmd->execute_cmd = sbc_compare_and_write;
- cmd->transport_complete_callback = compare_and_write_callback;
+ sbc_setup_compare_and_write(cmd, ops, sectors);
break;
case READ_CAPACITY:
size = READ_CAP_LEN;
diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 6cd7222..7db8c22 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -525,8 +525,16 @@ spc_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
/*
* Set MAXIMUM COMPARE AND WRITE LENGTH
*/
- if (dev->dev_attrib.emulate_caw)
- buf[5] = 0x01;
+ if (dev->dev_attrib.emulate_caw) {
+ if (!dev->dev_attrib.max_compare_and_write_len)
+ /*
+ * if backing device does not have special handling
+ * then sbc will support up to 1 block.
+ */
+ buf[5] = 0x01;
+ else
+ buf[5] = dev->dev_attrib.max_compare_and_write_len;
+ }

/*
* Set OPTIMAL TRANSFER LENGTH GRANULARITY
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 9ea0d5f..e7706f9 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1637,6 +1637,7 @@ void transport_generic_request_failure(struct se_cmd *cmd,
case TCM_LOGICAL_BLOCK_GUARD_CHECK_FAILED:
case TCM_LOGICAL_BLOCK_APP_TAG_CHECK_FAILED:
case TCM_LOGICAL_BLOCK_REF_TAG_CHECK_FAILED:
+ case TCM_MISCOMPARE_VERIFY:
break;
case TCM_OUT_OF_RESOURCES:
sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 9adc1bc..06924b1 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -53,6 +53,7 @@ struct sbc_ops {
sense_reason_t (*execute_write_same)(struct se_cmd *cmd);
sense_reason_t (*execute_write_same_unmap)(struct se_cmd *cmd);
sense_reason_t (*execute_unmap)(struct se_cmd *cmd);
+ sense_reason_t (*execute_compare_and_write)(struct se_cmd *cmd);
};

int transport_subsystem_register(struct se_subsystem_api *);
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 23c518a..bc0a26e 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -697,6 +697,7 @@ struct se_dev_attrib {
u32 unmap_granularity;
u32 unmap_granularity_alignment;
u32 max_write_same_len;
+ u32 max_compare_and_write_len;
u32 max_bytes_per_io;
struct se_device *da_dev;
struct config_group da_group;
--
1.7.1