Linux Virtualization - Jul 2012 - [PATCH-v2] virtio-scsi: Add vdrv->scan for post VIRTIO_CONFIG_S_DRIVER_OK LUN scanning

From: Nicholas Bellinger <nab at linux-iscsi.org>

This patch changes virtio-scsi to use a new virtio_driver->scan() callback
so that scsi_scan_host() can be properly invoked once virtio_dev_probe() has
set add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK) to signal active virtio-ring
operation, instead of from within virtscsi_probe().

This fixes a bug where SCSI LUN scanning for both virtio-scsi-raw and
virtio-scsi/tcm_vhost setups was happening before VIRTIO_CONFIG_S_DRIVER_OK
had been set, causing VIRTIO_SCSI_S_BAD_TARGET to occur.  This fixes a bug
with virtio-scsi/tcm_vhost where LUN scan was not detecting LUNs.

Tested with virtio-scsi-raw + virtio-scsi/tcm_vhost w/ IBLOCK on 3.5-rc2 code.

(nab: Fix up minor apply fuzz against scsi.git/misc)

Cc: Paolo Bonzini <pbonzini at redhat.com>
Cc: Stefan Hajnoczi <stefanha at linux.vnet.ibm.com>
Cc: Zhi Yong Wu <wuzhy at cn.ibm.com>
Cc: Christoph Hellwig <hch at lst.de>
Cc: Hannes Reinecke <hare at suse.de>
Cc: James Bottomley <JBottomley at Parallels.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
---
 drivers/scsi/virtio_scsi.c |   15 ++++++++++++---
 drivers/virtio/virtio.c    |    5 ++++-
 include/linux/virtio.h     |    1 +
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index ae3bef7..c7030fb 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -571,6 +571,13 @@ static struct virtio_scsi_target_state *virtscsi_alloc_tgt(
 	return tgt;
 }
 
+static void virtscsi_scan(struct virtio_device *vdev)
+{
+	struct Scsi_Host *shost = (struct Scsi_Host *)vdev->priv;
+
+	scsi_scan_host(shost);
+}
+
 static void virtscsi_remove_vqs(struct virtio_device *vdev)
 {
 	struct Scsi_Host *sh = virtio_scsi_host(vdev);
@@ -677,9 +684,10 @@ static int __devinit virtscsi_probe(struct virtio_device
*vdev)
 	err = scsi_add_host(shost, &vdev->dev);
 	if (err)
 		goto scsi_add_host_failed;
-
-	scsi_scan_host(shost);
-
+	/*
+	 * scsi_scan_host() happens in virtscsi_scan() via virtio_driver->scan()
+	 * after VIRTIO_CONFIG_S_DRIVER_OK has been set..
+	 */
 	return 0;
 
 scsi_add_host_failed:
@@ -735,6 +743,7 @@ static struct virtio_driver virtio_scsi_driver = {
 	.driver.owner = THIS_MODULE,
 	.id_table = id_table,
 	.probe = virtscsi_probe,
+	.scan = virtscsi_scan,
 #ifdef CONFIG_PM
 	.freeze = virtscsi_freeze,
 	.restore = virtscsi_restore,
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index f355807..c3b3f7f 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -141,8 +141,11 @@ static int virtio_dev_probe(struct device *_d)
 	err = drv->probe(dev);
 	if (err)
 		add_status(dev, VIRTIO_CONFIG_S_FAILED);
-	else
+	else {
 		add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
+		if (drv->scan)
+			drv->scan(dev);
+	}
 
 	return err;
 }
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 8efd28a..a1ba8bb 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -92,6 +92,7 @@ struct virtio_driver {
 	const unsigned int *feature_table;
 	unsigned int feature_table_size;
 	int (*probe)(struct virtio_device *dev);
+	void (*scan)(struct virtio_device *dev);
 	void (*remove)(struct virtio_device *dev);
 	void (*config_changed)(struct virtio_device *dev);
 #ifdef CONFIG_PM
-- 
1.7.2.5

On Wed, 2012-07-11 at 21:22 +0000, Nicholas A. Bellinger
wrote:
> From: Nicholas Bellinger <nab at linux-iscsi.org>
> 
> This patch changes virtio-scsi to use a new virtio_driver->scan()
callback
> so that scsi_scan_host() can be properly invoked once virtio_dev_probe()
has
> set add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK) to signal active virtio-ring
> operation, instead of from within virtscsi_probe().
> 
> This fixes a bug where SCSI LUN scanning for both virtio-scsi-raw and
> virtio-scsi/tcm_vhost setups was happening before VIRTIO_CONFIG_S_DRIVER_OK
> had been set, causing VIRTIO_SCSI_S_BAD_TARGET to occur.  This fixes a bug
> with virtio-scsi/tcm_vhost where LUN scan was not detecting LUNs.
> 
> Tested with virtio-scsi-raw + virtio-scsi/tcm_vhost w/ IBLOCK on 3.5-rc2
code.
> 
> (nab: Fix up minor apply fuzz against scsi.git/misc)
> 
> Cc: Paolo Bonzini <pbonzini at redhat.com>
> Cc: Stefan Hajnoczi <stefanha at linux.vnet.ibm.com>
> Cc: Zhi Yong Wu <wuzhy at cn.ibm.com>
> Cc: Christoph Hellwig <hch at lst.de>
> Cc: Hannes Reinecke <hare at suse.de>
> Cc: James Bottomley <JBottomley at Parallels.com>
> Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Was the change so great that it needs re acking?

I assume it also now no longer applies to stable because it will reject?

James

Il 12/07/2012 09:23, James Bottomley ha scritto:
>> > Cc: Paolo Bonzini <pbonzini at redhat.com>
>> > Cc: Stefan Hajnoczi <stefanha at linux.vnet.ibm.com>
>> > Cc: Zhi Yong Wu <wuzhy at cn.ibm.com>
>> > Cc: Christoph Hellwig <hch at lst.de>
>> > Cc: Hannes Reinecke <hare at suse.de>
>> > Cc: James Bottomley <JBottomley at Parallels.com>
>> > Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
> Was the change so great that it needs re acking?
Not really, but anyway

Acked-by: Paolo Bonzini <pbonzini at redhat.com>
> I assume it also now no longer applies to stable because it will reject?
Yes, stable will have to use v1.

Paolo