When running multipath on a VM if all available paths go down
the driver can schedule large amounts of storvsc_remove_lun
work items to the same lun. In response to the failing paths
typically storvsc responds by taking host->scan_mutex and issuing
a TUR per lun. If there has been heavy IO to the failed device
all the failed IOs are returned from the host. A remove lun work
item is issued per failed IO. If the outstanding TURs have not been
completed in a timely manner the scan_mutex is never released or
released too late. Consequently the many remove lun work items are
not completed as scsi_remove_device also tries to take host->scan_mutex.
This results in dragging the VM down and sometimes completely.
This patch only allows one remove lun to be issued to a particular
lun while it is an instantiated member of the scsi stack.
Signed-off-by: Cathy Avery <cavery@xxxxxxxxxx>
---
drivers/scsi/storvsc_drv.c | 33 +++++++++++++++++++++++++++++++--
1 file changed, 31 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 016639d..9dbb5bf 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -478,6 +478,10 @@ struct storvsc_device {
u64 port_name;
};
+struct storvsc_dev_hostdata {
+ atomic_t req_remove_lun;
+};
+
struct hv_host_device {
struct hv_device *dev;
unsigned int port;
@@ -918,6 +922,8 @@ static void storvsc_handle_error(struct vmscsi_request *vm_srb,
u8 asc, u8 ascq)
{
struct storvsc_scan_work *wrk;
+ struct storvsc_dev_hostdata *hostdata;
+ struct scsi_device *sdev;
void (*process_err_fn)(struct work_struct *work);
bool do_work = false;
@@ -953,8 +959,17 @@ static void storvsc_handle_error(struct vmscsi_request *vm_srb,
}
break;
case SRB_STATUS_INVALID_LUN:
- do_work = true;
- process_err_fn = storvsc_remove_lun;
+ sdev = scsi_device_lookup(host, 0, vm_srb->target_id,
+ vm_srb->lun);
+ if (sdev) {
+ hostdata = sdev->hostdata;
+ if (hostdata &&
+ !atomic_cmpxchg(&hostdata->req_remove_lun, 0, 1)) {
+ do_work = true;
+ process_err_fn = storvsc_remove_lun;
+ }
+ scsi_device_put(sdev);
+ }
break;
case SRB_STATUS_ABORTED:
if (vm_srb->srb_status & SRB_STATUS_AUTOSENSE_VALID &&
@@ -1426,9 +1441,22 @@ static int storvsc_device_configure(struct scsi_device *sdevice)
sdevice->no_write_same = 0;
}
+ sdevice->hostdata = kzalloc(sizeof(struct storvsc_dev_hostdata),
+ GFP_ATOMIC);
+ if (!sdevice->hostdata)
+ return -ENOMEM;
+
return 0;
}
+static void storvsc_device_destroy(struct scsi_device *sdevice)
+{
+ if (sdevice->hostdata) {
+ kfree(sdevice->hostdata);
+ sdevice->hostdata = NULL;
+ }
+}
+
static int storvsc_get_chs(struct scsi_device *sdev, struct block_device * bdev,
sector_t capacity, int *info)
{
@@ -1669,6 +1697,7 @@ static struct scsi_host_template scsi_driver = {
.eh_timed_out = storvsc_eh_timed_out,
.slave_alloc = storvsc_device_alloc,
.slave_configure = storvsc_device_configure,
+ .slave_destroy = storvsc_device_destroy,
.cmd_per_lun = 255,
.this_id = -1,
.use_clustering = ENABLE_CLUSTERING,
--
2.5.0
