[PATCH 2/2] Drivers: scsi: storvsc: Force discovery of LUNs that may have been removed.

K. Y. Srinivasan
2014-08-17T03:09:48Z

The host asks the guest to scan when a LUN is removed or added.
The only way a guest can identify the removed LUN is when an I/O is
attempted on a removed LUN - the SRB status code indicates that the LUN
is invalid. We currently handle this SRB status and remove the device.

Rather than waiting for an I/O to remove the device, force the discovery of
LUNs that may have been removed prior to discovering LUNs that may have
been added.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
drivers/scsi/storvsc_drv.c | 26 ++++++++++++++++++++++++++
1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 02d1db6..fb38ca9 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -430,10 +430,36 @@ static void storvsc_host_scan(struct work_struct *work)
{
struct storvsc_scan_work *wrk;
struct Scsi_Host *host;
+ struct scsi_device *sdev;
+ unsigned long flags;

wrk = container_of(work, struct storvsc_scan_work, work);
host = wrk->host;

+ /*
+ * Before scanning the host, first check to see if any of the
+ * currrently known devices have been hot removed. We issue a
+ * "unit ready" command against all currently known devices.
+ * This I/O will result in an error for devices that have been
+ * removed. As part of handling the I/O error, we remove the device.
+ *
+ * When a LUN is added or removed, the host sends us a signal to
+ * scan the host. Thus we are forced to discover the LUNs that
+ * may have been removed this way.
+ */
+ mutex_lock(&host->scan_mutex);
+ spin_lock_irqsave(host->host_lock, flags);
+ list_for_each_entry(sdev, &host->__devices, siblings) {
+ spin_unlock_irqrestore(host->host_lock, flags);
+ scsi_test_unit_ready(sdev, 1, 1, NULL);
+ spin_lock_irqsave(host->host_lock, flags);
+ continue;
+ }
+ spin_unlock_irqrestore(host->host_lock, flags);
+ mutex_unlock(&host->scan_mutex);
+ /*
+ * Now scan the host to discover LUNs that may have been added.
+ */
scsi_scan_host(host);

kfree(wrk);
--
1.7.4.1