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scsi: storvsc: Allow only one remove lun work item to be issued per lun 

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@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Long Li <longli@microsoft.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Cathy Avery 2017-10-31 08:52:06 -04:00 committed by Martin K. Petersen
parent ca6958b4da
commit 436ad94133
1 changed files with 21 additions and 5 deletions
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26
drivers/scsi/storvsc_drv.c
View File

@ -486,6 +486,7 @@ struct hv_host_device {
unsigned int port;
unsigned char path;
unsigned char target;
struct workqueue_struct *handle_error_wq;
};
struct storvsc_scan_work {
@ -922,6 +923,7 @@ static void storvsc_handle_error(struct vmscsi_request *vm_srb,
{
struct storvsc_scan_work *wrk;
void (*process_err_fn)(struct work_struct *work);
struct hv_host_device *host_dev = shost_priv(host);
bool do_work = false;
switch (SRB_STATUS(vm_srb->srb_status)) {
@ -988,7 +990,7 @@ static void storvsc_handle_error(struct vmscsi_request *vm_srb,
wrk->lun = vm_srb->lun;
wrk->tgt_id = vm_srb->target_id;
INIT_WORK(&wrk->work, process_err_fn);
schedule_work(&wrk->work);
queue_work(host_dev->handle_error_wq, &wrk->work);
}
@ -1803,10 +1805,19 @@ static int storvsc_probe(struct hv_device *device,
if (stor_device->num_sc != 0)
host->nr_hw_queues = stor_device->num_sc + 1;
/*
* Set the error handler work queue.
*/
host_dev->handle_error_wq =
alloc_ordered_workqueue("storvsc_error_wq_%d",
WQ_MEM_RECLAIM,
host->host_no);
if (!host_dev->handle_error_wq)
goto err_out2;
/* Register the HBA and start the scsi bus scan */
ret = scsi_add_host(host, &device->device);
if (ret != 0)
goto err_out2;
goto err_out3;
if (!dev_is_ide) {
scsi_scan_host(host);
@ -1815,7 +1826,7 @@ static int storvsc_probe(struct hv_device *device,
device->dev_instance.b[4]);
ret = scsi_add_device(host, 0, target, 0);
if (ret)
goto err_out3;
goto err_out4;
}
#if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
if (host->transportt == fc_transport_template) {
@ -1827,14 +1838,17 @@ static int storvsc_probe(struct hv_device *device,
fc_host_port_name(host) = stor_device->port_name;
stor_device->rport = fc_remote_port_add(host, 0, &ids);
if (!stor_device->rport)
goto err_out3;
goto err_out4;
}
#endif
return 0;
err_out3:
err_out4:
scsi_remove_host(host);
err_out3:
destroy_workqueue(host_dev->handle_error_wq);
err_out2:
/*
* Once we have connected with the host, we would need to
@ -1858,6 +1872,7 @@ static int storvsc_remove(struct hv_device *dev)
{
struct storvsc_device *stor_device = hv_get_drvdata(dev);
struct Scsi_Host *host = stor_device->host;
struct hv_host_device *host_dev = shost_priv(host);
#if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
if (host->transportt == fc_transport_template) {
@ -1865,6 +1880,7 @@ static int storvsc_remove(struct hv_device *dev)
fc_remove_host(host);
}
#endif
destroy_workqueue(host_dev->handle_error_wq);
scsi_remove_host(host);
storvsc_dev_remove(dev);
scsi_host_put(host);