[PATCH] scsi: storvsc: Add the support of hibernation

[Dexuan Cui <decui@microsoft.com>]

When we're in storvsc_suspend(), we're sure the SCSI layer has quiesced the
scsi device by scsi_bus_suspend() -> ... -> scsi_device_quiesce(), so the
low level SCSI adapter driver only needs to suspend/resume its own state.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---

This patch is basically a pure Hyper-V specific change and it has a
build dependency on the commit 271b2224d42f ("Drivers: hv: vmbus: Implement
suspend/resume for VSC drivers for hibernation"), which is on Sasha Levin's
Hyper-V tree's hyperv-next branch:
https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git/log/?h=hyperv-next

I request this patch should go through Sasha's tree rather than the
SCSI tree.

 drivers/scsi/storvsc_drv.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index ed8b9ac..9fbf604 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1727,6 +1727,13 @@ enum {
 
 MODULE_DEVICE_TABLE(vmbus, id_table);
 
+static const struct { guid_t guid; } fc_guid = { HV_SYNTHFC_GUID };
+
+static bool hv_dev_is_fc(struct hv_device *hv_dev)
+{
+	return guid_equal(&fc_guid.guid, &hv_dev->dev_type);
+}
+
 static int storvsc_probe(struct hv_device *device,
 			const struct hv_vmbus_device_id *dev_id)
 {
@@ -1935,11 +1942,45 @@ static int storvsc_remove(struct hv_device *dev)
 	return 0;
 }
 
+static int storvsc_suspend(struct hv_device *hv_dev)
+{
+	struct storvsc_device *stor_device = hv_get_drvdata(hv_dev);
+	struct Scsi_Host *host = stor_device->host;
+	struct hv_host_device *host_dev = shost_priv(host);
+
+	storvsc_wait_to_drain(stor_device);
+
+	drain_workqueue(host_dev->handle_error_wq);
+
+	vmbus_close(hv_dev->channel);
+
+	memset(stor_device->stor_chns, 0,
+	       num_possible_cpus() * sizeof(void *));
+
+	kfree(stor_device->stor_chns);
+	stor_device->stor_chns = NULL;
+
+	cpumask_clear(&stor_device->alloced_cpus);
+
+	return 0;
+}
+
+static int storvsc_resume(struct hv_device *hv_dev)
+{
+	int ret;
+
+	ret = storvsc_connect_to_vsp(hv_dev, storvsc_ringbuffer_size,
+				     hv_dev_is_fc(hv_dev));
+	return ret;
+}
+
 static struct hv_driver storvsc_drv = {
 	.name = KBUILD_MODNAME,
 	.id_table = id_table,
 	.probe = storvsc_probe,
 	.remove = storvsc_remove,
+	.suspend = storvsc_suspend,
+	.resume = storvsc_resume,
 	.driver = {
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 	},
-- 
1.8.3.1