On 4/3/2014 12:35 PM, Nicholas A. Bellinger wrote:
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch enables the use of READ_STRIP software emulation in
target_complete_ok_work() code for I/O READs.
This is useful when the fabric does not support READ_STRIP hardware
offload, but would still like to interact with backend device
that have T10 PI enabled.
Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
Cc: Quinn Tran <quinn.tran@xxxxxxxxxx>
Cc: Giridhar Malavali <giridhar.malavali@xxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_transport.c | 33 ++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 530a9e8..a184103 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1905,6 +1905,24 @@ static void transport_handle_queue_full(
schedule_work(&cmd->se_dev->qf_work_queue);
}
+static bool target_check_read_strip(struct se_cmd *cmd)
+{
+ sense_reason_t rc;
+
+ if (cmd->prot_op != TARGET_PROT_DIN_STRIP)
+ return false;
+
+ if (!(cmd->se_sess->sup_prot_ops & TARGET_PROT_DIN_STRIP)) {
+ rc = sbc_dif_read_strip(cmd);
+ if (rc) {
+ cmd->pi_err = rc;
+ return true;
+ }
+ }
+
+ return false;
+}
+
static void target_complete_ok_work(struct work_struct *work)
{
struct se_cmd *cmd = container_of(work, struct se_cmd, work);
@@ -1969,6 +1987,21 @@ static void target_complete_ok_work(struct work_struct *work)
cmd->data_length;
}
spin_unlock(&cmd->se_lun->lun_sep_lock);
+ /*
+ * Perform READ_STRIP of PI using software emulation when
+ * backend had PI enabled, if the transport will not be
+ * performing hardware READ_STRIP offload.
+ */
You always call read_strip() even if the operation is not READ_STRIP
(the routine won't do anything in this case).
Personally, I usually prefer to avoid calling a routine rather then
calling it and perform the checks there.
I suggest:
if (cmd->prot_op == TARGET_PROT_DIN_STRIP &&
target_check_read_strip(cmd)) {
ret = transport_send_check_condition_and_sense(cmd, cmd->pi_err, 0);
...
}
+ if (target_check_read_strip(cmd)) {
+ ret = transport_send_check_condition_and_sense(cmd,
+ cmd->pi_err, 0);
+ if (ret == -EAGAIN || ret == -ENOMEM)
+ goto queue_full;
+
+ transport_lun_remove_cmd(cmd);
+ transport_cmd_check_stop_to_fabric(cmd);
+ return;
+ }
trace_target_cmd_complete(cmd);
ret = cmd->se_tfo->queue_data_in(cmd);
--
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