From dcece99e86b1191d2789fb5b5caa4c5b7fc2bfef Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare@suse.de>
Date: Wed, 11 Mar 2020 00:25:36 +0800
Subject: [PATCH] scsi: core: add scsi_host_busy_iter()
References: bsc#1179851
Git-commit: dcece99e86b1191d2789fb5b5caa4c5b7fc2bfef
Patch-mainline: 5.7-rc1

Add an iterator scsi_host_busy_iter() to traverse all busy commands.  If
locking against concurrent command completions is required, it has to be
provided by the caller.

Link: https://lore.kernel.org/r/20200228075318.91255-11-hare@suse.de
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
---
 drivers/scsi/hosts.c     |   34 ++++++++++++++++++++++++++++++++++
 include/scsi/scsi_host.h |    3 +++
 2 files changed, 37 insertions(+)

--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -648,3 +648,40 @@ void scsi_flush_work(struct Scsi_Host *s
 	flush_workqueue(shost->work_q);
 }
 EXPORT_SYMBOL_GPL(scsi_flush_work);
+
+struct scsi_host_busy_iter_data {
+	bool (*fn)(struct scsi_cmnd *, void *, bool);
+	void *priv;
+};
+
+static bool __scsi_host_busy_iter_fn(struct request *req, void *priv,
+				   bool reserved)
+{
+	struct scsi_host_busy_iter_data *iter_data = priv;
+	struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
+
+	return iter_data->fn(sc, iter_data->priv, reserved);
+}
+
+/**
+ * scsi_host_busy_iter - Iterate over all busy commands
+ * @shost:	Pointer to Scsi_Host.
+ * @fn:		Function to call on each busy command
+ * @priv:	Data pointer passed to @fn
+ *
+ * If locking against concurrent command completions is required
+ * ithas to be provided by the caller
+ **/
+void scsi_host_busy_iter(struct Scsi_Host *shost,
+			 bool (*fn)(struct scsi_cmnd *, void *, bool),
+			 void *priv)
+{
+	struct scsi_host_busy_iter_data iter_data = {
+		.fn = fn,
+		.priv = priv,
+	};
+
+	blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
+				&iter_data);
+}
+EXPORT_SYMBOL_GPL(scsi_host_busy_iter);
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -774,6 +774,9 @@ static inline int scsi_host_scan_allowed
 extern void scsi_unblock_requests(struct Scsi_Host *);
 extern void scsi_block_requests(struct Scsi_Host *);
 
+void scsi_host_busy_iter(struct Scsi_Host *,
+			 bool (*fn)(struct scsi_cmnd *, void *, bool), void *priv);
+
 struct class_container;
 
 /*