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Commit eeb64d23 authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target: Add support for TMR percpu reference counting 



This patch introduces TMR percpu reference counting using
se_lun->lun_ref in transport_lookup_tmr_lun(), following
how existing non TMR per se_lun reference counting works
within transport_lookup_cmd_lun().

It also adds explicit transport_lun_remove_cmd() calls to
drop the reference in the three tmr related locations that
invoke transport_cmd_check_stop_to_fabric();

   - target_tmr_work() during normal ->queue_tm_rsp()
   - target_complete_tmr_failure() during error ->queue_tm_rsp()
   - transport_generic_handle_tmr() during early failure

Also, note the exception paths in transport_generic_free_cmd()
and transport_cmd_finish_abort() already check SCF_SE_LUN_CMD,
and will invoke transport_lun_remove_cmd() when necessary.

Reviewed-by: default avatarHimanshu Madhani <himanshu.madhani@cavium.com>
Reviewed-by: default avatarQuinn Tran <quinn.tran@cavium.com>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 12f66e4a

drivers/target/target_core_device.c

+10 −4
Original line number Diff line number Diff line
@@ -168,11 +168,20 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u64 unpacked_lun) 
	rcu_read_lock();

	deve = target_nacl_find_deve(nacl, unpacked_lun);

	if (deve) {

		se_cmd->se_lun = rcu_dereference(deve->se_lun);

		se_lun = rcu_dereference(deve->se_lun);



		if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {

			se_lun = NULL;

			goto out_unlock;

		}



		se_cmd->se_lun = rcu_dereference(deve->se_lun);

		se_cmd->pr_res_key = deve->pr_res_key;

		se_cmd->orig_fe_lun = unpacked_lun;

		se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;

		se_cmd->lun_ref_active = true;

	}

out_unlock:

	rcu_read_unlock();



	if (!se_lun) {
@@ -182,9 +191,6 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u64 unpacked_lun) 
			unpacked_lun);

		return -ENODEV;

	}

	/*

	 * XXX: Add percpu se_lun->lun_ref reference count for TMR

	 */

	se_cmd->se_dev = rcu_dereference_raw(se_lun->lun_se_dev);

	se_tmr->tmr_dev = rcu_dereference_raw(se_lun->lun_se_dev);

drivers/target/target_core_transport.c

+3 −0
Original line number Diff line number Diff line
@@ -1590,6 +1590,7 @@ static void target_complete_tmr_failure(struct work_struct *work) 
	se_cmd->se_tmr_req->response = TMR_LUN_DOES_NOT_EXIST;

	se_cmd->se_tfo->queue_tm_rsp(se_cmd);



	transport_lun_remove_cmd(se_cmd);

	transport_cmd_check_stop_to_fabric(se_cmd);

}
@@ -3201,6 +3202,7 @@ static void target_tmr_work(struct work_struct *work) 
	cmd->se_tfo->queue_tm_rsp(cmd);



check_stop:

	transport_lun_remove_cmd(cmd);

	transport_cmd_check_stop_to_fabric(cmd);

}
@@ -3223,6 +3225,7 @@ int transport_generic_handle_tmr( 
		pr_warn_ratelimited("handle_tmr caught CMD_T_ABORTED TMR %d"

			"ref_tag: %llu tag: %llu\n", cmd->se_tmr_req->function,

			cmd->se_tmr_req->ref_task_tag, cmd->tag);

		transport_lun_remove_cmd(cmd);

		transport_cmd_check_stop_to_fabric(cmd);

		return 0;

	}