scsi: core: Replace scsi_target_block() with scsi_block_targets()

All callers (fc_remote_port_delete(), __iscsi_block_session(),
__srp_start_tl_fail_timers(), srp_reconnect_rport(), snic_tgt_del()) pass
parent devices of scsi_target devices to scsi_target_block().

Rename the function to scsi_block_targets(), and simplify it by assuming
that it is always passed a parent device. Also, have callers pass the
Scsi_Host pointer to scsi_block_targets(), as every caller has this pointer
readily available.

Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin Wilck <mwilck@suse.com>
Link: https://lore.kernel.org/r/20230614103616.31857-7-mwilck@suse.com
Cc: Karan Tilak Kumar <kartilak@cisco.com>
Cc: Sesidhar Baddela <sebaddel@cisco.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: mwilck

drivers/scsi/scsi_lib.c

@@ -2890,20 +2890,26 @@ target_block(struct device *dev, void *data)
 	return 0;
 }
 
+/**
+ * scsi_block_targets - transition all SCSI child devices to SDEV_BLOCK state
+ * @dev: a parent device of one or more scsi_target devices
+ * @shost: the Scsi_Host to which this device belongs
+ *
+ * Iterate over all children of @dev, which should be scsi_target devices,
+ * and switch all subordinate scsi devices to SDEV_BLOCK state. Wait for
+ * ongoing scsi_queue_rq() calls to finish. May sleep.
+ *
+ * Note:
+ * @dev must not itself be a scsi_target device.
+ */
 void
-scsi_target_block(struct device *dev)
+scsi_block_targets(struct Scsi_Host *shost, struct device *dev)
 {
-	struct Scsi_Host *shost = dev_to_shost(dev);
-
-	if (scsi_is_target_device(dev))
-		starget_for_each_device(to_scsi_target(dev), NULL,
-					scsi_device_block);
-	else
-		device_for_each_child(dev, NULL, target_block);
-
+	WARN_ON_ONCE(scsi_is_target_device(dev));
+	device_for_each_child(dev, NULL, target_block);
 	blk_mq_wait_quiesce_done(&shost->tag_set);
 }
-EXPORT_SYMBOL_GPL(scsi_target_block);
+EXPORT_SYMBOL_GPL(scsi_block_targets);
 
 static void
 device_unblock(struct scsi_device *sdev, void *data)

drivers/scsi/scsi_transport_fc.c

@@ -3451,7 +3451,7 @@ fc_remote_port_delete(struct fc_rport  *rport)
 
 	spin_unlock_irqrestore(shost->host_lock, flags);
 
-	scsi_target_block(&rport->dev);
+	scsi_block_targets(shost, &rport->dev);
 
 	/* see if we need to kill io faster than waiting for device loss */
 	if ((rport->fast_io_fail_tmo != -1) &&

drivers/scsi/scsi_transport_iscsi.c

@@ -1943,13 +1943,14 @@ static void __iscsi_block_session(struct work_struct *work)
 	struct iscsi_cls_session *session =
 			container_of(work, struct iscsi_cls_session,
 				     block_work);
+	struct Scsi_Host *shost = iscsi_session_to_shost(session);
 	unsigned long flags;
 
 	ISCSI_DBG_TRANS_SESSION(session, "Blocking session\n");
 	spin_lock_irqsave(&session->lock, flags);
 	session->state = ISCSI_SESSION_FAILED;
 	spin_unlock_irqrestore(&session->lock, flags);
-	scsi_target_block(&session->dev);
+	scsi_block_targets(shost, &session->dev);
 	ISCSI_DBG_TRANS_SESSION(session, "Completed SCSI target blocking\n");
 	if (session->recovery_tmo >= 0)
 		queue_delayed_work(session->workq,

drivers/scsi/scsi_transport_srp.c

@@ -396,7 +396,7 @@ static void srp_reconnect_work(struct work_struct *work)
 }
 
 /*
- * scsi_target_block() must have been called before this function is
+ * scsi_block_targets() must have been called before this function is
  * called to guarantee that no .queuecommand() calls are in progress.
  */
 static void __rport_fail_io_fast(struct srp_rport *rport)
@@ -480,7 +480,7 @@ static void __srp_start_tl_fail_timers(struct srp_rport *rport)
 	    srp_rport_set_state(rport, SRP_RPORT_BLOCKED) == 0) {
 		pr_debug("%s new state: %d\n", dev_name(&shost->shost_gendev),
 			 rport->state);
-		scsi_target_block(&shost->shost_gendev);
+		scsi_block_targets(shost, &shost->shost_gendev);
 		if (fast_io_fail_tmo >= 0)
 			queue_delayed_work(system_long_wq,
 					   &rport->fast_io_fail_work,
@@ -548,7 +548,7 @@ int srp_reconnect_rport(struct srp_rport *rport)
 		 * later is ok though, scsi_internal_device_unblock_nowait()
 		 * treats SDEV_TRANSPORT_OFFLINE like SDEV_BLOCK.
 		 */
-		scsi_target_block(&shost->shost_gendev);
+		scsi_block_targets(shost, &shost->shost_gendev);
 	res = rport->state != SRP_RPORT_LOST ? i->f->reconnect(rport) : -ENODEV;
 	pr_debug("%s (state %d): transport.reconnect() returned %d\n",
 		 dev_name(&shost->shost_gendev), rport->state, res);

drivers/scsi/snic/snic_disc.c

@@ -214,7 +214,7 @@ snic_tgt_del(struct work_struct *work)
 		scsi_flush_work(shost);
 
 	/* Block IOs on child devices, stops new IOs */
-	scsi_target_block(&tgt->dev);
+	scsi_block_targets(shost, &tgt->dev);
 
 	/* Cleanup IOs */
 	snic_tgt_scsi_abort_io(tgt);

include/scsi/scsi_device.h

@@ -450,7 +450,7 @@ extern void scsi_scan_target(struct device *parent, unsigned int channel,
 			     unsigned int id, u64 lun,
 			     enum scsi_scan_mode rescan);
 extern void scsi_target_reap(struct scsi_target *);
-extern void scsi_target_block(struct device *);
+void scsi_block_targets(struct Scsi_Host *shost, struct device *dev);
 extern void scsi_target_unblock(struct device *, enum scsi_device_state);
 extern void scsi_remove_target(struct device *);
 extern const char *scsi_device_state_name(enum scsi_device_state);