[PATCH 1/3] scsi: introduce scsi_host_busy()

[Ming Lei <ming.lei@xxxxxxxxxx>]

This patch introduces SCSI middle layer API of scsi_host_busy() for
drivers to read the host-wide counter of scsi_host->host_busy.

Cc: Omar Sandoval <osandov@xxxxxx>,
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>,
Cc: James Bottomley <james.bottomley@xxxxxxxxxxxxxxxxxxxxx>,
Cc: Christoph Hellwig <hch@xxxxxx>,
Cc: Don Brace <don.brace@xxxxxxxxxxxxx>
Cc: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Laurence Oberman <loberman@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
 drivers/scsi/hosts.c     | 10 ++++++++++
 include/scsi/scsi_host.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 7649d63a1b8d..69beb30205f1 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -565,6 +565,16 @@ struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
 EXPORT_SYMBOL(scsi_host_get);
 
 /**
+ * scsi_host_busy - Return the host busy counter
+ * @shost:	Pointer to Scsi_Host to inc.
+ **/
+int scsi_host_busy(struct Scsi_Host *shost)
+{
+	return atomic_read(&shost->host_busy);
+}
+EXPORT_SYMBOL(scsi_host_busy);
+
+/**
  * scsi_host_put - dec a Scsi_Host ref count
  * @shost:	Pointer to Scsi_Host to dec.
  **/
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 12f454cb6f61..44ab89268f30 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -758,6 +758,7 @@ extern void scsi_scan_host(struct Scsi_Host *);
 extern void scsi_rescan_device(struct device *);
 extern void scsi_remove_host(struct Scsi_Host *);
 extern struct Scsi_Host *scsi_host_get(struct Scsi_Host *);
+extern int scsi_host_busy(struct Scsi_Host *shost);
 extern void scsi_host_put(struct Scsi_Host *t);
 extern struct Scsi_Host *scsi_host_lookup(unsigned short);
 extern const char *scsi_host_state_name(enum scsi_host_state);
-- 
2.9.5