From 436ad941335386c5fc7faa915a8fbdfe8c908084 Mon Sep 17 00:00:00 2001 From: Cathy Avery Date: Tue, 31 Oct 2017 08:52:06 -0400 Subject: [PATCH] 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 Reviewed-by: Christoph Hellwig Reviewed-by: Long Li Signed-off-by: Martin K. Petersen --- drivers/scsi/storvsc_drv.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 5e7200f..7e3cd12 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -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); -- 2.7.4