[PATCH RFC 3/6] scsi: core: Add scsi_get_dev()

[John Garry <john.garry@huawei.com>]

Add a function which allows use to alloc a sdev with configurable
device parent, and channel:id:lun.

This is useful for separating adding a scsi device into separate alloc
and scan steps.

Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/scsi/scsi_scan.c | 25 +++++++++++++++++++++++++
 include/scsi/scsi_host.h |  3 +++
 2 files changed, 28 insertions(+)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 3759b1a77504..fd15ddac01b6 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1988,3 +1988,28 @@ void scsi_forget_host(struct Scsi_Host *shost)
 	spin_unlock_irqrestore(shost->host_lock, flags);
 }
 
+struct scsi_device *scsi_get_dev(struct device *parent, int channel, uint id, u64 lun)
+{
+	struct Scsi_Host *shost = dev_to_shost(parent);
+	struct scsi_device *sdev = NULL;
+	struct scsi_target *starget;
+
+	mutex_lock(&shost->scan_mutex);
+	if (!scsi_host_scan_allowed(shost))
+		goto out;
+
+	starget = scsi_alloc_target(parent, 0, id);
+	if (!starget)
+		goto out;
+
+	sdev = scsi_alloc_sdev(starget, 0, NULL);
+	if (sdev)
+		sdev->borken = 0;
+	else
+		scsi_target_reap(starget);
+	put_device(&starget->dev);
+ out:
+	mutex_unlock(&shost->scan_mutex);
+	return sdev;
+}
+EXPORT_SYMBOL(scsi_get_dev);
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index aa7b7496c93a..5142c7df7647 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -794,7 +794,10 @@ void scsi_host_busy_iter(struct Scsi_Host *,
 
 struct class_container;
 
+extern struct scsi_device *scsi_get_dev(struct device *parent, int channel, uint id, u64 lun);
+
 /*
+
  * DIF defines the exchange of protection information between
  * initiator and SBC block device.
  *
-- 
2.35.3