Re: [PATCH 2/3] target: Add TARGET_SCF_LOOKUP_LUN_FROM_TAG support for ABORT_TASK

[Tran, Quinn]

Looks Good.

Regards,
Quinn Tran

-----Original Message-----
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Date: Saturday, June 3, 2017 at 3:10 PM
To: target-devel <target-devel@xxxxxxxxxxxxxxx>
Cc: linux-scsi <linux-scsi@xxxxxxxxxxxxxxx>, lkml <linux-kernel@xxxxxxxxxxxxxxx>, Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>, "Madhani, Himanshu" <Himanshu.Madhani@xxxxxxxxxx>, "Tran, Quinn" <Quinn.Tran@xxxxxxxxxx>, Mike Christie <mchristi@xxxxxxxxxx>, Hannes Reinecke <hare@xxxxxxxx>, Christoph Hellwig <hch@xxxxxx>
Subject: [PATCH 2/3] target: Add TARGET_SCF_LOOKUP_LUN_FROM_TAG support for ABORT_TASK

    From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
    
    This patch introduces support in target_submit_tmr() for locating a
    unpacked_lun from an existing se_cmd->tag during ABORT_TASK.
    
    When TARGET_SCF_LOOKUP_LUN_FROM_TAG is set, target_submit_tmr()
    will do the extra lookup via target_lookup_lun_from_tag() and
    subsequently invoke transport_lookup_tmr_lun() so a proper
    percpu se_lun->lun_ref is taken before workqueue dispatch into
    se_device->tmr_wq happens.
    
    Aside from the extra target_lookup_lun_from_tag(), the existing
    code-path remains unchanged.
    
    Cc: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
    Cc: Quinn Tran <quinn.tran@xxxxxxxxxx>
    Cc: Mike Christie <mchristi@xxxxxxxxxx>
    Cc: Hannes Reinecke <hare@xxxxxxxx>
    Cc: Christoph Hellwig <hch@xxxxxx>
    Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
    ---
     drivers/target/target_core_transport.c | 53 ++++++++++++++++++++++++++++------
     include/target/target_core_base.h      |  3 +-
     2 files changed, 46 insertions(+), 10 deletions(-)
    
    diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
    index 83bfc97..dbb8101 100644
    --- a/drivers/target/target_core_transport.c
    +++ b/drivers/target/target_core_transport.c
    @@ -1592,6 +1592,29 @@ static void target_complete_tmr_failure(struct work_struct *work)
     	transport_cmd_check_stop_to_fabric(se_cmd);
     }
     
    +static bool target_lookup_lun_from_tag(struct se_session *se_sess, u64 tag,
    +				       u64 *unpacked_lun)
    +{
    +	struct se_cmd *se_cmd;
    +	unsigned long flags;
    +	bool ret = false;
    +
    +	spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
    +	list_for_each_entry(se_cmd, &se_sess->sess_cmd_list, se_cmd_list) {
    +		if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
    +			continue;
    +
    +		if (se_cmd->tag == tag) {
    +			*unpacked_lun = se_cmd->orig_fe_lun;
    +			ret = true;
    +			break;
    +		}
    +	}
    +	spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
    +
    +	return ret;
    +}
    +
     /**
      * target_submit_tmr - lookup unpacked lun and submit uninitialized se_cmd
      *                     for TMR CDBs
    @@ -1639,19 +1662,31 @@ int target_submit_tmr(struct se_cmd *se_cmd, struct se_session *se_sess,
     		core_tmr_release_req(se_cmd->se_tmr_req);
     		return ret;
     	}
    +	/*
    +	 * If this is ABORT_TASK with no explicit fabric provided LUN,
    +	 * go ahead and search active session tags for a match to figure
    +	 * out unpacked_lun for the original se_cmd.
    +	 */
    +	if (tm_type == TMR_ABORT_TASK && (flags & TARGET_SCF_LOOKUP_LUN_FROM_TAG)) {
    +		if (!target_lookup_lun_from_tag(se_sess, tag, &unpacked_lun))
    +			goto failure;
    +	}
     
     	ret = transport_lookup_tmr_lun(se_cmd, unpacked_lun);
    -	if (ret) {
    -		/*
    -		 * For callback during failure handling, push this work off
    -		 * to process context with TMR_LUN_DOES_NOT_EXIST status.
    -		 */
    -		INIT_WORK(&se_cmd->work, target_complete_tmr_failure);
    -		schedule_work(&se_cmd->work);
    -		return 0;
    -	}
    +	if (ret)
    +		goto failure;
    +
     	transport_generic_handle_tmr(se_cmd);
     	return 0;
    +
    +	/*
    +	 * For callback during failure handling, push this work off
    +	 * to process context with TMR_LUN_DOES_NOT_EXIST status.
    +	 */
    +failure:
    +	INIT_WORK(&se_cmd->work, target_complete_tmr_failure);
    +	schedule_work(&se_cmd->work);
    +	return 0;
     }
     EXPORT_SYMBOL(target_submit_tmr);
     
    diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
    index db2c7b3..a3af69f 100644
    --- a/include/target/target_core_base.h
    +++ b/include/target/target_core_base.h
    @@ -188,7 +188,8 @@ enum target_sc_flags_table {
     	TARGET_SCF_BIDI_OP		= 0x01,
     	TARGET_SCF_ACK_KREF		= 0x02,
     	TARGET_SCF_UNKNOWN_SIZE		= 0x04,
    -	TARGET_SCF_USE_CPUID	= 0x08,
    +	TARGET_SCF_USE_CPUID		= 0x08,
    +	TARGET_SCF_LOOKUP_LUN_FROM_TAG	= 0x10,
     };
     
     /* fabric independent task management function values */
    -- 
    1.9.1