[PATCH v2 2/3] scsi: introduce 'blocked' sysfs api

[Ye Bin <yebin@huaweicloud.com>]

From: Ye Bin <yebin10@huawei.com>

Introduce 'blocked' sysfs api to control scsi host blocking IO.
Use this founction for test. Perhaps we can use this to do some fault
recovery or firmware upgrades, as long as the driver support is good,
it may be insensitive to the upper layer.

Signed-off-by: Ye Bin <yebin10@huawei.com>
---
 drivers/scsi/scsi_sysfs.c | 32 ++++++++++++++++++++++++++++++++
 include/scsi/scsi_host.h  |  3 +++
 2 files changed, 35 insertions(+)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 903aa9de46e5..cad1981ab528 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -345,6 +345,37 @@ store_shost_eh_deadline(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(eh_deadline, S_IRUGO | S_IWUSR, show_shost_eh_deadline, store_shost_eh_deadline);
 
+static ssize_t
+store_shost_blocked(struct device *dev, struct device_attribute *attr,
+		    const char *buf, size_t count)
+{
+	int err;
+	bool blocked;
+	struct Scsi_Host *shost = class_to_shost(dev);
+
+	err = kstrtobool(buf, &blocked);
+	if (err)
+		return err;
+
+	if (shost->host_blockio != blocked) {
+		shost->host_blockio = blocked;
+		if (!blocked)
+			scsi_run_host_queues(shost);
+	}
+
+	return count;
+}
+
+static ssize_t
+show_shost_blocked(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct Scsi_Host *shost = class_to_shost(dev);
+
+	return snprintf(buf, 20, "%d\n", shost->host_blockio);
+}
+static DEVICE_ATTR(blocked, S_IRUGO | S_IWUSR,
+		   show_shost_blocked, store_shost_blocked);
+
 shost_rd_attr(unique_id, "%u\n");
 shost_rd_attr(cmd_per_lun, "%hd\n");
 shost_rd_attr(can_queue, "%d\n");
@@ -397,6 +428,7 @@ static struct attribute *scsi_sysfs_shost_attrs[] = {
 	&dev_attr_host_reset.attr,
 	&dev_attr_eh_deadline.attr,
 	&dev_attr_nr_hw_queues.attr,
+	&dev_attr_blocked.attr,
 	NULL
 };
 
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 587cc767bb67..3e916dbac1cb 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -659,6 +659,9 @@ struct Scsi_Host {
 	/* The transport requires the LUN bits NOT to be stored in CDB[1] */
 	unsigned no_scsi2_lun_in_cdb:1;
 
+	/* True host will blocking IO */
+	unsigned host_blockio:1;
+
 	/*
 	 * Optional work queue to be utilized by the transport
 	 */
-- 
2.31.1