target: Add SCF_ACK_KREF flag for acknowledgement kref

When TARGET_SCF_ACK_KREF is in use with target_submit_cmd() for
setting the extra acknowledgement reference to se_cmd->cmd_kref,
go ahead and set SCF_ACK_KREF in order to be used later by
abort task.
Reported-by: Roland Dreier <roland@purestorage.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_transport.c

@@ -4030,8 +4030,10 @@ void target_get_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd,
 	 * fabric acknowledgement that requires two target_put_sess_cmd()
 	 * invocations before se_cmd descriptor release.
 	 */
-	if (ack_kref == true)
+	if (ack_kref == true) {
 		kref_get(&se_cmd->cmd_kref);
+		se_cmd->se_cmd_flags |= SCF_ACK_KREF;
+	}
 
 	spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
 	list_add_tail(&se_cmd->se_cmd_list, &se_sess->sess_cmd_list);

include/target/target_core_base.h

@@ -184,7 +184,8 @@ enum se_cmd_flags_table {
 	SCF_ALUA_NON_OPTIMIZED		= 0x00040000,
 	SCF_DELAYED_CMD_FROM_SAM_ATTR	= 0x00080000,
 	SCF_UNUSED			= 0x00100000,
-	SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC = 0x00400000,
+	SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC = 0x00200000,
+	SCF_ACK_KREF			= 0x00400000,
 };
 
 /* struct se_dev_entry->lun_flags and struct se_lun->lun_access */